JP7630494B2 - Thermal printhead and method for manufacturing the same - Google Patents

Description

The present disclosure relates to a thermal printhead. The present disclosure also relates to a method for manufacturing a thermal printhead.

Patent Documents 1 and 2 disclose an example of a conventional thermal printhead. The thermal printhead disclosed in Patent Document 1 comprises a plurality of heat generating sections formed on a substrate and arranged along the main scanning direction. These heat generating sections are composed of a resistor layer formed on the substrate and a wiring layer partially overlapping the resistor layer. Each heat generating section is a part of the resistor layer exposed from the wiring layer. When a current flows through the wiring layer under control, one or more selected heat generating sections generate heat.

In the thermal printhead described in Patent Document 1, silicon is selected as the material of the substrate. The resistor layer and the wiring layer are formed by utilizing a semiconductor process. Meanwhile, the wiring layer includes a common wiring and a plurality of individual wirings. In the substrate, the common wiring and the plurality of individual wirings are arranged on both sides of the plurality of heat generating parts in the sub-scanning direction. Here, in order to improve the printing quality, measures may be taken to increase the number of the plurality of individual wirings, increase the number of the plurality of heat generating parts, and reduce the width (length in the main scanning direction) of each of the plurality of heat generating parts. This makes it possible to perform more minute printing on the recording medium. However, in this case, there may be a shortage of space on the substrate for arranging the common wiring. When the space is insufficient, it is necessary to make the substrate larger. Making the substrate larger leads to a deterioration in the manufacturing efficiency of the thermal printhead, so improvement in this respect is desired. In addition, improvement is also desired for the thermal printhead described in Patent Document 2 so that it can be made smaller depending on the application.

JP 2017-7203 A JP 2019-166824 A

In view of the above circumstances, a first aspect of the present disclosure has an objective of providing a thermal printhead and a manufacturing method thereof that are capable of performing finer printing without increasing the size of the substrate.

According to one embodiment of the first aspect of the present disclosure, a thermal printhead is provided. The thermal printhead includes a semiconductor substrate having a main surface and a back surface spaced apart from each other in the thickness direction and having a first through portion formed therein penetrating from the main surface to the back surface, a resistor layer including a plurality of heat generating portions arranged in the main scanning direction and formed on the main surface, a first electrode formed on the back surface, a wiring layer formed on the resistor layer and conducting to the plurality of heat generating portions, and a first through wiring housed in the first through portion. The wiring layer includes a common wiring located on a first side in the sub-scanning direction with respect to the plurality of heat generating portions. The first through wiring is connected to the common wiring and the first electrode.

Preferably, the thermal printhead further includes a plurality of second electrodes formed on the rear surface, and a plurality of second through wirings. The wiring layer includes a plurality of individual wirings located on a second side in the sub-scanning direction from the plurality of heat generating portions. The semiconductor substrate is formed with a plurality of second through portions that penetrate from the main surface to the rear surface and are located on the opposite side of the plurality of heat generating portions in the sub-scanning direction from the first through portions. The plurality of second through wirings are individually accommodated in the plurality of second through portions. Each of the plurality of second through wirings is connected to one of the plurality of individual wirings and one of the plurality of second electrodes.

Preferably, the main surface includes a base surface and a convex surface that bulges from the base surface in the thickness direction, the convex surface extends along the main scanning direction, and the multiple heat generating portions are formed on the convex surface.

Preferably, the convex surface includes a top surface parallel to the base surface and a pair of inclined surfaces connected to the top surface and the base surface and positioned apart from each other in the sub-scanning direction, and the multiple heat generating portions are formed on the top surface.

Preferably, a portion of the common wiring and a portion of each of the plurality of individual wirings are formed on one of the pair of inclined surfaces.

Preferably, the pair of inclined surfaces are inclined relative to the base surface so as to approach each other from the base surface to the top surface.

Preferably, each of the pair of inclined surfaces includes a first region connected to the base surface and a second region connected to the top surface and the first region, and the inclination angle of the second region relative to the base surface is smaller than the inclination angle of the first region relative to the base surface.

Preferably, the semiconductor substrate comprises a single crystal silicon material.

Preferably, the thermal printhead further comprises a first insulating layer covering the main surface, and the resistor layer is in contact with the first insulating layer.

Preferably, the semiconductor substrate has a first inner surface connected to the main surface and the back surface and defining the first penetration portion, and a plurality of second inner surfaces connected to the main surface and the back surface and defining each of the plurality of second penetration portions, and the first insulating layer covers the first inner surface and the plurality of second inner surfaces.

Preferably, the thermal printhead further includes a second insulating layer covering the back surface and connected to the first insulating layer, and the first electrode and the plurality of second electrodes are in contact with the second insulating layer.

Preferably, the thermal printhead further includes a heat dissipation layer located between the first electrode and the multiple second electrodes in the sub-scanning direction and formed in contact with the second insulating layer, and when viewed along the thickness direction, the heat dissipation layer overlaps the multiple heat generating portions.

Preferably, the thermal printhead further includes a wiring board facing the rear surface and to which the first electrode and a plurality of second electrodes are bonded, the wiring board having a heat sink to which the heat dissipation layer is bonded.

Preferably, the thermal printhead further includes a protective layer covering a portion of the main surface, the plurality of heating portions, and the wiring layer.

According to another embodiment of the first aspect of the present disclosure, a method for manufacturing a thermal printhead is provided. The method includes the steps of forming a first recess in a thickness direction from a main surface of a substrate made of a semiconductor material, the first recess being recessed in the thickness direction from the main surface, forming a resistor layer including a plurality of heating portions arranged in a main scanning direction on the main surface and in the first recess, forming a wiring layer on the resistor layer that is conductive to the plurality of heating portions, removing a portion of the substrate located on the opposite side of the main surface in the thickness direction, and forming an electrode on the substrate that is located on the opposite side of the wiring layer from the substrate in the thickness direction and is conductive to the wiring layer. The step of forming the wiring layer includes the steps of forming a common wiring located on a first side of the plurality of heating portions in the sub-scanning direction, and a first through wiring that is accommodated in the first recess and connected to the common wiring. The step of removing a portion of the substrate includes removing the portion of the substrate until a portion of the first through wiring is exposed from the substrate. The step of forming the electrode includes a step of forming a first electrode that is electrically connected to the common wiring, the first electrode being formed so as to be in contact with the first through wiring in the step of forming the first electrode.

Preferably, the manufacturing method further includes, between the step of forming the first recess and the step of forming the resistor layer, a step of forming a plurality of second recesses recessed from the main surface in the thickness direction of the substrate and located on the opposite side of the plurality of heat generating parts in the sub-scanning direction from the first recesses. In the step of forming the resistor layer, a part of the resistor layer is formed in the plurality of second recesses. The step of forming the wiring layer includes a step of forming a plurality of individual wirings located on the second side of the plurality of heat generating parts in the sub-scanning direction, and a plurality of second through wirings individually accommodated in the plurality of second recesses and individually connected to the plurality of individual wirings. In the step of removing a part of the substrate, the part of the substrate is removed until a part of the plurality of second through wirings is exposed from the substrate. The step of forming the electrode includes a step of forming a plurality of second electrodes individually conducting to the plurality of individual wirings. In the step of forming the plurality of second electrodes, the plurality of second electrodes are formed so that the plurality of second electrodes are individually in contact with the plurality of second through wirings.

Preferably, the main surface includes a base surface and a convex surface that bulges from the base surface in the thickness direction. The manufacturing method further includes, before the step of forming the first recess, a step of forming a convex portion on the base material, the convex portion bulging from the base surface in the thickness direction and extending along the main scanning direction and including the convex surface. In the step of forming the resistor layer, the plurality of heating portions are formed on the convex surface.

Preferably, the semiconductor material comprises a single crystal material of silicon.

The thermal printhead and manufacturing method disclosed herein make it possible to perform finer printing without increasing the size of the substrate.

Other features and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.

FIG. 1 is a plan view of a thermal printhead according to a first embodiment of a first aspect of the present disclosure. FIG. 2 is a plan view of a main portion of the thermal printhead shown in FIG. 1 . FIG. 3 is a partially enlarged view of FIG. 2 . FIG. 3 is a partially enlarged view of FIG. 2 . FIG. 2 is a bottom view of a main portion of the thermal printhead shown in FIG. 1 . 2 is a cross-sectional view taken along line 006-006 in FIG. 1. FIG. 2 is a cross-sectional view of a main part of the thermal printhead shown in FIG. FIG. 8 is a partially enlarged view of FIG. 7 . FIG. 8 is a partially enlarged view of FIG. 7 . FIG. 8 is a partially enlarged view of FIG. 7 . 2 is a cross-sectional view taken along line 011-011 in FIG. 1. 2 is a cross-sectional view taken along line 012-012 in FIG. 1. 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. 2A to 2C are partially enlarged cross-sectional views illustrating a manufacturing process for a main part of the thermal printhead shown in FIG. 1 . 2A to 2C are partially enlarged cross-sectional views illustrating a manufacturing process for a main part of the thermal printhead shown in FIG. 1 . 2A to 2C are partially enlarged cross-sectional views illustrating a manufacturing process for a main part of the thermal printhead shown in FIG. 1 . 2A to 2C are partially enlarged cross-sectional views illustrating a manufacturing process for a main part of the thermal printhead shown in FIG. 1 . 2A to 2C are partially enlarged cross-sectional views illustrating a manufacturing process for a main part of the thermal printhead shown in FIG. 1 . 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. FIG. 2 is a cross-sectional view of a main part of a thermal printhead according to a second embodiment of the first aspect of the present disclosure. FIG. 35 is a partially enlarged view of FIG. 34 . FIG. 2 is a plan view showing a thermal printhead according to an embodiment of a second aspect of the present disclosure. This is a cross-sectional view taken along line 037-037 in Figure 36. FIG. 38 is a partially enlarged view of FIG. 37 . FIG. 37 is an enlarged plan view of a main portion of the thermal printhead shown in FIG. 36. 37 is a cross-sectional view showing a step of an example of a method for manufacturing the thermal printhead shown in FIG. 36. A cross-sectional view showing a process following Figure 40. A cross-sectional view showing a process following Figure 41. A cross-sectional view showing a process following Figure 42. A cross-sectional view showing a process following Figure 43. A cross-sectional view showing a process following Figure 44. FIG. 46 is a plan view showing a process following that of FIG. 45 . FIG. 47 is a partially enlarged view of FIG. 46. FIG. 48 is a partially enlarged view of FIG. 47. FIG. 47 is a schematic plan view showing a process following FIG. 46 . FIG. 50 is a schematic plan view showing a process following FIG. 49 . 51 is a schematic plan view showing a process following FIG. 50 . FIG. 52 is a schematic plan view showing a process following FIG. 51 . 37 is a plan view showing a case where the substrate is composed of a large number of individual chips, as compared with the thermal printhead shown in FIG. 36. 37 is a plan view showing a case where the substrate is composed of a smaller number of individual chips compared to the thermal printhead shown in FIG. 36. FIG. 11 is a plan view showing a modified example of the thermal printhead according to the second aspect of the present disclosure. This is a cross-sectional view taken along line 056-056 in Figure 55. FIG. 2 is a plan view of a thermal printhead according to a first embodiment of a third aspect of the present disclosure, seen through a protective layer. FIG. 58 is a plan view of the essential parts of the thermal printhead shown in FIG. 57, seen through the protective layer. FIG. 59 is a partially enlarged view of FIG. 58. This is a cross-sectional view taken along line 060-060 in Figure 57. A cross-sectional view of a main part of the thermal printhead shown in Figure 57. FIG. 62 is a partially enlarged view of FIG. 61. FIG. 58 is a partially enlarged view of FIG. 57, showing the insulating layer, the resistor layer, the wiring layer, the first substrate, the second substrate, and a plurality of second interconnects. This is a cross-sectional view taken along line 064-064 in Figure 63. 65 is a cross-sectional view taken along line 065-065 in FIG. 63, showing only the base material and the first interconnection wiring. FIG. 65 is a partially enlarged view of FIG. 64 . FIG. 58 is a cross-sectional view showing a modified example of the thermal printhead shown in FIG. 57, illustrating only the base material and the first interconnection wiring. FIG. 58 is a cross-sectional view showing a modified example of the thermal printhead shown in FIG. 57, illustrating only the base material and the first interconnection wiring. 58A to 58C are cross-sectional views illustrating the manufacturing process of the main part of the thermal printhead shown in FIG. 57. 58A to 58C are cross-sectional views illustrating the manufacturing process of the main part of the thermal printhead shown in FIG. 57. 58A to 58C are cross-sectional views illustrating the manufacturing process of the main part of the thermal printhead shown in FIG. 57. 58A to 58C are cross-sectional views illustrating the manufacturing process of the main part of the thermal printhead shown in FIG. 57. 58 is a partially enlarged plan view illustrating the manufacturing process of the main part of the thermal printhead shown in FIG. 57. 58A to 58C are cross-sectional views illustrating the manufacturing process of the main part of the thermal printhead shown in FIG. 57. 58A to 58C are cross-sectional views illustrating the manufacturing process of the main part of the thermal printhead shown in FIG. 57. 58A to 58C are cross-sectional views illustrating the manufacturing process of the main part of the thermal printhead shown in FIG. 57. 58A to 58C are cross-sectional views illustrating the manufacturing process of the main part of the thermal printhead shown in FIG. 57. 58A to 58C are cross-sectional views illustrating the manufacturing process of the main part of the thermal printhead shown in FIG. 57. 58A to 58C are cross-sectional views illustrating the manufacturing process of the main part of the thermal printhead shown in FIG. 57. 58A to 58C are cross-sectional views illustrating the manufacturing process of the main part of the thermal printhead shown in FIG. 57. FIG. 11 is a plan view of a thermal printhead according to a second embodiment of the third aspect of the present disclosure, seen through a protective layer. FIG. 11 is a plan view of a thermal printhead according to a third embodiment of the third aspect of the present disclosure, seen through a protective layer. FIG. 58 is a partially enlarged view of FIG. 57, showing the insulating layer, the resistor layer, the wiring layer (excluding a part of the common wiring), and a plurality of second interconnects. FIG. 11 is a cross-sectional view of a main part of a thermal printhead according to a fourth embodiment of the third aspect of the present disclosure. FIG. 85 is a partially enlarged view of FIG. 84 . FIG. 13 is a cross-sectional view of a main part of a thermal printhead according to a fifth embodiment of the third aspect of the present disclosure. FIG. 87 is a partially enlarged view of FIG. 86. 87A to 87C are cross-sectional views illustrating the manufacturing process of the main part of the thermal printhead shown in FIG. 86. FIG. 11 is a plan view of a thermal printhead according to a first embodiment of the fourth aspect of the present disclosure, showing a protective layer and a covering layer. FIG. 90 is a plan view of the essential parts of the thermal printhead shown in FIG. 89, showing the protective layer and the covering layer. FIG. 91 is a partially enlarged view of FIG. 90. This is a cross-sectional view taken along line 092-092 in Figure 89. A cross-sectional view of a main part of the thermal printhead shown in Figure 89. FIG. 94 is a partially enlarged view of FIG. 93. 89A to 89C are cross-sectional views illustrating the manufacturing process of the main part of the thermal printhead shown in FIG. 89A to 89C are cross-sectional views illustrating the manufacturing process of the main part of the thermal printhead shown in FIG. 89A to 89C are cross-sectional views illustrating the manufacturing process of the main part of the thermal printhead shown in FIG. 89A to 89C are cross-sectional views illustrating the manufacturing process of the main part of the thermal printhead shown in FIG. 89A to 89C are cross-sectional views illustrating the manufacturing process of the main part of the thermal printhead shown in FIG. 89A to 89C are cross-sectional views illustrating the manufacturing process of the main part of the thermal printhead shown in FIG. 89A to 89C are cross-sectional views illustrating the manufacturing process of the main part of the thermal printhead shown in FIG. 89A to 89C are cross-sectional views illustrating the manufacturing process of the main part of the thermal printhead shown in FIG. 89A to 89C are cross-sectional views illustrating the manufacturing process of the main part of the thermal printhead shown in FIG. FIG. 90 is a partially enlarged cross-sectional view of a modified example of the thermal printhead shown in FIG. 89. 90A to 90C are cross-sectional views illustrating a modified example of the manufacturing process for the main part of the thermal printhead shown in FIG. 89. FIG. 11 is a plan view of a thermal printhead according to a second embodiment of the fourth aspect of the present disclosure, showing a protective layer and a covering layer. A plan view of the main part of the thermal printhead shown in Figure 106, showing the protective layer and the covering layer. FIG. 108 is a partially enlarged view of FIG.

Various embodiments for implementing the present disclosure will be described with reference to the accompanying drawings. Of Figs. 1 to 108, Figs. 1 to 35 are explanatory diagrams of a first aspect of the present disclosure. Similarly, Figs. 36 to 56 are explanatory diagrams of a second aspect of the present disclosure, Figs. 57 to 88 are explanatory diagrams of a third aspect of the present disclosure, and Figs. 89 to 108 are explanatory diagrams of a fourth aspect of the present disclosure.

First, the thermal printhead A10 according to the first embodiment of the first aspect will be described with reference to FIGS. 1 to 12. The thermal printhead A10 is a main unit of a thermal printer. The thermal printhead A10 mainly includes a substrate 1, a first insulating layer 21, a second insulating layer 22, a resistor layer 3, a wiring layer 4, a first through-hole wiring 511, a plurality of second through-hole wirings 512, a first electrode 521, a plurality of second electrodes 522, a heat dissipation layer 53, and a protective layer 6. In addition to these, the thermal printhead A10 includes a wiring substrate 71, a heat sink 72, a plurality of driving elements 73, a plurality of first wires 74, a plurality of second wires 75, a sealing resin 76, and a connector 77. Here, in FIG. 1, the illustration of the protective layer 6, the plurality of first wires 74, the plurality of second wires 75, and the sealing resin 76 is omitted. In FIGS. 2 to 4, the illustration of the protective layer 6 is omitted.

In this disclosure, the main scanning direction of the thermal printhead A10 is referred to as the "x direction" and the sub-scanning direction (orthogonal to the main scanning direction) is referred to as the "y direction" as appropriate. The direction extending through the thickness of the substrate 1 is referred to as the "z direction". The z direction is orthogonal to both the x direction and the y direction. In the following description, "when viewed along the z direction" and "when viewed along the thickness direction" have the same meaning, and may be referred to as "in a planar view".

As shown in FIG. 6, in the thermal printhead A10, the main parts of the thermal printhead A10, including the substrate 1, are bonded to a wiring substrate 71. The wiring substrate 71 is bonded to a heat sink 72. The wiring substrate 71 is sandwiched between the main parts of the thermal printhead A10 and the heat sink 72 in the z direction. On the substrate 1, a plurality of heat generating parts 31 (described later) that form part of the resistor layer 3 and are arranged in the x direction are formed. The plurality of heat generating parts 31 are selectively heated by a plurality of driving elements 73 mounted on the wiring substrate 71. The plurality of driving elements 73 are driven according to a print signal transmitted from the outside via a connector 77. As shown in FIG. 6, a platen roller 79 constituting a thermal printer presses a recording medium 78, such as thermal paper, against the plurality of heat generating parts 31, so that the plurality of heat generating parts 31 print on the recording medium 78. For convenience of explanation, the side of the supply source of the recording medium 78 in FIG. 6 (the right side in FIG. 6) is called the "upstream side". In FIG. 6, the side to which the recording medium 78 is discharged (the left side in FIG. 6) is referred to as the "downstream side."

As shown in Fig. 1, the substrate 1 is a strip extending in the x direction when viewed along the z direction. The substrate 1 is made of a semiconductor material. The semiconductor material includes a single crystal material of silicon (Si).

As shown in FIG. 6, the substrate 1 has a principal surface 10 and a rear surface 13. The principal surface 10 and rear surface 13 of the substrate 1 both have Miller indices of (100). The principal surface 10 and rear surface 13 face opposite each other in the z direction. In the thermal printhead A10, the principal surface 10 faces the platen roller 79 shown in FIG. 6, and the rear surface 13 faces the wiring board 71. As shown in FIG. 7, the principal surface 10 includes a base surface 11 and a convex surface 12. The base surface 11 is parallel to the rear surface 13. The convex surface 12 bulges out from the base surface 11 in the z direction. The convex surface 12 extends along the x direction.

As shown in FIG. 8, the convex surface 12 has a top surface 121 and a pair of inclined surfaces 122. The top surface 121 is located away from the base surface 11 in the z direction and is parallel to the base surface 11. The pair of inclined surfaces 122 are located away from each other in the y direction. The pair of inclined surfaces 122 are connected to the top surface 121 and the base surface 11. The pair of inclined surfaces 122 are inclined with respect to the base surface 11 so as to approach each other from the base surface 11 to the top surface 121. The inclination angle α of each of the pair of inclined surfaces 122 with respect to the base surface 11 is the same.

7, the substrate 1 is formed with a convex portion 17, a first through portion 18, and a plurality of second through portions 19. The convex portion 17 bulges from the base surface 11 in the z direction and extends along the x direction. The convex surface 12 is the surface of the convex portion 17. Therefore, the configuration of the convex surface 12 is based on the shape of the convex portion 17. The first through portion 18 is located on one side (downstream side) of the convex portion 17 in the y direction. The plurality of second through portions 19 are located on the other side (upstream side) of the convex portion 17 in the y direction. That is, the plurality of second through portions 19 are located on the opposite side of the first through portion 18 with respect to the plurality of heat generating portions 31 (described later) of the resistor layer 3 in the y direction. The first through portion 18 and the plurality of second through portions 19 penetrate the substrate 1 from the base surface 11 (main surface 10) to the back surface 13. 2 and 5, when viewed along the z direction, the first through-holes 18 form slits extending in the x direction. When viewed along the z direction, the second through-holes 19 are arranged in a staggered arrangement with respect to the x direction.

7, the substrate 1 has a first inner peripheral surface 181 and a plurality of second inner peripheral surfaces 191. The first inner peripheral surface 181 and each of the plurality of second inner peripheral surfaces 191 are connected to the base surface 11 (main surface 10) and the back surface 13. The first inner peripheral surface 181 defines a first through-hole 18. The first inner peripheral surface 181 is made up of a plurality of regions inclined with respect to each of the base surface 11 and the back surface 13. Of the plurality of regions, a pair of the regions located apart from each other in the y direction are inclined with respect to the base surface 11 and the back surface 13 so as to approach each other from the base surface 11 to the back surface 13. Each of the plurality of second inner peripheral surfaces 191 defines one of the plurality of second through-holes 19. Each of the plurality of second inner peripheral surfaces 191 stands up along the z direction.

7, the first insulating layer 21 covers the main surface 10, the first inner peripheral surface 181, and the plurality of second inner peripheral surfaces 191 of the substrate 1. The first insulating layer 21 electrically insulates the substrate 1 from the resistor layer 3, the wiring layer 4, the first through-wires 511, and the plurality of second through-wires 512. The first insulating layer 21 is made of silicon dioxide (TEOS-SiO ₂ ) made from tetraethyl orthosilicate (TEOS) as a raw material, for example. An example thickness of the first insulating layer 21 is 1 μm or more and 15 μm or less.

As shown in FIG. 7, the second insulating layer 22 covers the rear surface 13 of the substrate 1. At the boundaries between the rear surface 13 and the first inner peripheral surface 181 and the plurality of second inner peripheral surfaces 191 of the substrate 1, the second insulating layer 22 is connected to the first insulating layer 21. The second insulating layer 22 electrically insulates the substrate 1 from the first electrode 521, the plurality of second electrodes 522, and the heat dissipation layer 53. The second insulating layer 22 is made of, for example, silicon dioxide or silicon nitride (Si ₃ N ₄ ). As shown in FIG. 9 and FIG. 10, the second insulating layer 22 has a first opening 221 and a plurality of second openings 222 formed therein. In the z-direction, the first opening 221 and the second opening 222 penetrate the second insulating layer 22. The first opening 221 leads to the first penetration portion 18 of the substrate 1. The multiple second openings 222 communicate with the multiple second through-holes 19 of the substrate 1 individually.

As shown in Figures 7 to 10, the resistor layer 3 is formed on the main surface 10 of the substrate 1. The resistor layer 3 is in contact with the first insulating layer 21. As a result, in the thermal printhead A10, the first insulating layer 21 is sandwiched between the substrate 1 and the resistor layer 3. Furthermore, a portion of the resistor layer 3 is accommodated in the first through-hole 18 and the multiple second through-holes 19 of the substrate 1. The resistor layer 3 is made of, for example, tantalum nitride (TaN). An example thickness of the resistor layer 3 is 0.02 μm or more and 0.1 μm or less.

2, 3 and 8, the resistor layer 3 includes a plurality of heat generating portions 31. In the resistor layer 3, the plurality of heat generating portions 31 are portions exposed from the wiring layer 4. When electricity is selectively applied to the plurality of heat generating portions 31 from the wiring layer 4, the plurality of heat generating portions 31 locally heat the recording medium 78 shown in FIG. 6. The plurality of heat generating portions 31 are arranged in the x direction. Of the plurality of heat generating portions 31, two adjacent heat generating portions 31 in the x direction are located apart from each other. In the convex surface 12 of the substrate 1, the plurality of heat generating portions 31 are formed on the top surface 121. As shown in FIG. 6, in the thermal printer, the platen roller 79 faces the plurality of heat generating portions 31.

As shown in Figures 7 to 10, the wiring layer 4 is formed on the resistor layer 3. The wiring layer 4 forms a conductive path for passing electricity through the multiple heating parts 31 of the resistor layer 3. The electrical resistivity of the wiring layer 4 is smaller than that of the resistor layer 3. The wiring layer 4 is a metal layer made of, for example, copper (Cu). An example of the thickness of the wiring layer 4 is 0.3 μm or more and 2.0 μm or less. In addition, the wiring layer 4 may be configured to be made of two metal layers, a titanium (Ti) layer laminated on the resistor layer 3 and a copper layer laminated on the titanium layer. In this case, an example of the thickness of the titanium layer is 0.1 μm or more and 0.2 μm or less.

2, the wiring layer 4 includes a common wiring 41 and a plurality of individual wirings 42. The common wiring 41 is located on one side in the y direction (downstream side) of the plurality of heat generating portions 31 of the resistor layer 3. The plurality of individual wirings 42 are located on the other side in the y direction (upstream side) of the plurality of heat generating portions 31. As shown in FIG. 3, when viewed along the z direction, the plurality of regions of the resistor layer 3 sandwiched between the common wiring 41 and the plurality of individual wirings 42 are the plurality of heat generating portions 31. As will be described later, a predetermined positive voltage is supplied to the common wiring 41 from a power supply terminal (not shown) of the connector 77.

2 and 3, the common wiring 41 has a base 411 and a plurality of extensions 412. In the y direction, the base 411 is located farthest from the plurality of heat generating parts 31 of the resistor layer 3. The base 411 is a strip extending in the x direction when viewed along the z direction. When viewed along the z direction, the base 411 overlaps the first through portion 18 of the substrate 1. The plurality of extensions 412 are strip-shaped extending from an end of the base 411 facing the convex portion 17 of the substrate 1 in the y direction toward the plurality of heat generating parts 31. The plurality of extensions 412 are arranged along the x direction. A portion of each of the plurality of extensions 412 is formed on the inclined surface 122 facing the base 411 of the pair of inclined surfaces 122 of the substrate 1. Therefore, a portion of the common wiring 41 is formed on the downstream inclined surface 122 of the pair of inclined surfaces 122. In the common wiring 41 , a current flows from a base portion 411 through a plurality of extension portions 412 to a plurality of heat generating portions 31 .

2 and 4, each of the multiple individual wirings 42 has a base 421 and an extension 422. In the y direction, the base 421 is located farthest from the multiple heat generating parts 31 of the resistor layer 3. The bases 421 of the multiple individual wirings 42 are arranged in a staggered arrangement in the x direction. When viewed along the z direction, the bases 421 of the multiple individual wirings 42 individually overlap the multiple second penetration parts 19 of the substrate 1. The extension 422 is a strip extending from an end of the base 421 facing the convex part 17 of the substrate 1 in the y direction toward the multiple heat generating parts 31. The extension 422 of the multiple individual wirings 42 is arranged along the x direction. The extension 422 of each of the multiple individual wirings 42 is formed on the inclined surface 122 facing the base 421 of the multiple individual wirings 42, out of a pair of inclined surfaces 122 of the substrate 1. Therefore, a portion of each of the multiple individual wirings 42 is formed on the upstream inclined surface 122 of the pair of inclined surfaces 122. In each of the multiple individual wirings 42, a current flows from the base 421 through the extension portion 422 to one of the multiple heat generating portions 31. When viewed along the z direction, each of the multiple heat generating portions 31 is sandwiched between one of the extension portions 422 of the multiple individual wirings 42 and one of the multiple extension portions 412 of the common wiring 41.

As shown in FIG. 7 and FIG. 9, the first through wiring 511 is accommodated in the first through portion 18 of the substrate 1. The first through wiring 511 has a base layer 511A and a main layer 511B. The base layer 511A is formed along the first inner peripheral surface 181 of the substrate 1 and is in contact with the resistor layer 3. The base layer 511A is connected to the base 411 of the common wiring 41. Therefore, the first through wiring 511 is connected to the common wiring 41. Furthermore, the base layer 511A is connected to the first opening 221 of the second insulating layer 22. The base layer 511A is made of the same metal layer as the metal layer constituting the wiring layer 4. The main layer 511B is surrounded by the base layer 511A and fills the first through portion 18. The volume of the main layer 511B is larger than the volume of the base layer 511A. The main layer 511B is made of, for example, copper.

7 and 10, the second through wirings 512 are individually accommodated in the second through portions 19 of the substrate 1. Each of the second through wirings 512 is formed along one of the second inner peripheral surfaces 191 of the substrate 1 and is in contact with the resistor layer 3. The second through wirings 512 are individually connected to the bases 421 of the individual wirings 42. Therefore, each of the second through wirings 512 is connected to one of the individual wirings 42. Furthermore, the second through wirings 512 are individually connected to the second openings 222 of the second insulating layer 22. Each of the second through wirings 512 is made of the same metal layer as the metal layer constituting the wiring layer 4.

5 and 7, the first electrode 521 is formed on the back surface 13 of the substrate 1. The first electrode 521 is in contact with the second insulating layer 22. The first electrode 521 is a strip extending in the x direction when viewed along the z direction. When viewed along the z direction, the first electrode 521 overlaps at least a part of the first through portion 18 of the substrate 1. As shown in FIG. 9, the first electrode 521 has an underlayer 521A and a main body layer 521B. The underlayer 521A is in contact with the second insulating layer 22. Furthermore, the underlayer 521A is in contact with the resistor layer 3 and the base layer 511A of the first through wiring 511 at the first opening 221 of the second insulating layer 22. As a result, the first electrode 521 is connected to the first through wiring 511 and is conductive to the common wiring 41 via the first through wiring 511. A predetermined positive voltage is applied to the first electrode 521. The underlayer 521A is composed of two metal layers: a barrier layer in contact with the second insulating layer 22, the resistor layer 3, and the first through-hole wiring 511, and a seed layer laminated on the barrier layer. The barrier layer is made of, for example, titanium. The seed layer is made of, for example, copper. The main layer 521B is laminated on the underlayer 521A. In the first electrode 521, the main layer 521B serves as a main conductive path. The main layer 521B is a metal layer made of, for example, copper.

5 and 7, the second electrodes 522 are formed on the rear surface 13 of the substrate 1. The second electrodes 522 are in contact with the second insulating layer 22. Each of the second electrodes 522 is rectangular when viewed along the z direction. When viewed along the z direction, the second electrodes 522 are individually overlapped with the second through-holes 19 of the substrate 1. As shown in FIG. 10, each of the second electrodes 522 has a base layer 522A and a main body layer 522B. The base layer 522A is in contact with the second insulating layer 22. Furthermore, the base layer 522A is in contact with the resistor layer 3 and any of the second through-hole wirings 512 in any of the second openings 222 of the second insulating layer 22. As a result, each of the second electrodes 522 is connected to any of the second through-hole wirings 512 and is conductive to any of the individual wirings 42 via the second through-hole wirings 512. The underlayer 522A is made of a metal layer. This metal layer is the same as the metal layer constituting the underlayer 521A of the first electrode 521. The main layer 522B is laminated on the underlayer 522A. In each of the multiple second electrodes 522, the main layer 522B serves as a main conductive path. The main layer 522B is made of a metal layer. This metal layer is the same as the metal layer constituting the main layer 521B of the first electrode 521.

As shown in FIG. 5 and FIG. 7, the heat dissipation layer 53 is formed on the rear surface 13 of the substrate 1 and in contact with the second insulating layer 22. In the y direction, the heat dissipation layer 53 is located between the first electrode 521 and the multiple second electrodes 522. The heat dissipation layer 53 is a strip extending in the x direction when viewed along the z direction. When viewed along the z direction, the heat dissipation layer 53 overlaps the multiple heat generating portions 31 of the resistor layer 3. As shown in FIG. 8, the heat dissipation layer 53 has a base layer 53A and a main body layer 53B. The base layer 53A is in contact with the second insulating layer 22. The base layer 53A is composed of a metal layer. The metal layer is the same as the metal layer constituting the base layer 521A of the first electrode 521. The main body layer 53B is laminated on the base layer 53A. The main body layer 53B is composed of a metal layer. This metal layer is the same as the metal layer constituting the main body layer 521B of the first electrode 521.

7, the protective layer 6 covers the main surface 10 of the substrate 1, a portion of each of the first through wirings 511, the multiple heat generating portions 31 of the resistor layer 3, and the wiring layer 4. The protective layer 6 has electrical insulation properties. The protective layer 6 is made of, for example, silicon dioxide, silicon nitride, silicon carbide (SiC), or aluminum nitride (AlN). Alternatively, the protective layer 6 may be a laminate made of multiple types of these materials. An example of the thickness of the protective layer 6 is 1.0 μm or more and 10 μm or less. In a thermal printer, the recording medium 78 shown in FIG. 6 is pressed against the area of the protective layer 6 that covers the multiple heat generating portions 31 by a platen roller 79.

As shown in Figure 6, the wiring board 71 is disposed opposite the rear surface 13 of the substrate 1. As shown in Figure 1, the area of the wiring board 71 is larger than the area of the substrate 1 when viewed along the z direction. When viewed along the z direction, the wiring board 71 is rectangular with the x direction as the longitudinal direction. The wiring board 71 is, for example, a PCB substrate. The substrate 1, a plurality of driving elements 73, and a connector 77 are mounted on the wiring board 71.

11 and 12, the wiring board 71 has a heat sink 711 and wiring 712. The heat sink 711 penetrates the wiring board 71 in the z-direction. The heat sink 711 is a metal layer made of copper, for example. A heat dissipation layer 53 is bonded to the heat sink 711. The wiring 712 is disposed on the upper surface of the wiring board 71. The wiring 712 forms a conductive path between the first electrode 521 and the multiple second electrodes 522, the multiple driving elements 73, and the connector 77 on the wiring board 71. The first electrode 521 and the multiple second electrodes 522 are each bonded to the wiring 712.

6, the heat sink 72 is located on the opposite side of the wiring board 71 from the substrate 1 in the z direction. The wiring board 71 is joined to the heat sink 72. When the thermal printhead A10 is in use, a portion of the heat generated from the multiple heat generating portions 31 of the resistor layer 3 is conducted to the heat sink 72 via the substrate 1 and the heat dissipation layer 53. The heat conducted to the heat sink 72 is dissipated to the outside. The heat sink 72 is made of, for example, aluminum (Al).

1 and 6, the multiple driving elements 73 are mounted on the wiring board 71 via an electrically insulating die bonding material (not shown). Each of the multiple driving elements (driver ICs) 73 is a semiconductor element in which various circuits are configured. Each of the multiple driving elements 73 is bonded to one end of each of the multiple first wires 74 and one end of each of the multiple second wires 75. The other end of each of the multiple first wires 74 is bonded to the wiring 712 of the wiring board 71 to which the multiple second electrodes 522 are bonded. The other end of each of the multiple second wires 75 is bonded to the wiring 712 that is conductive to the connector 77.

With the above-described configuration, a print signal, a control signal, and a predetermined positive voltage are input from the outside to the multiple drive elements 73 via the connector 77. The multiple drive elements 73 each perform a switching operation based on these electrical signals, thereby selectively applying a predetermined positive voltage or 0V to the multiple individual wirings 42. Since a predetermined positive voltage is applied to the common wiring 41, when 0V is applied to any one of the multiple individual wirings 42, a current flows from the common wiring 41 to any one of the multiple heat generating portions 31 of the resistor layer 3 that is conductive to that individual wiring 42. This causes the multiple heat generating portions 31 to selectively generate heat.

As shown in Fig. 6, the sealing resin 76 covers the driving elements 73, the first wires 74, the second wires 75, and a part of the wiring board 71. The sealing resin 76 has electrical insulation properties. The sealing resin 76 is a black, soft synthetic resin that is used, for example, as an underfill.

As shown in Figures 1 and 6, the connector 77 is mounted on one end (upstream side) of the wiring board 71 in the y direction. The connector 77 is connected to a thermal printer. The connector 77 has a plurality of pins (not shown). Some of the plurality of pins are conductive to the wiring 712 to which the first electrode 521 is joined. The remaining pins of the plurality of pins are conductive to the wiring 712 of the wiring board 71 to which the plurality of second wires 75 are joined.

Next, an example of a manufacturing method for the thermal printhead A10 will be described with reference to Figures 13 to 34. Here, the cross-sectional positions in Figures 13 to 33 (excluding Figures 28 to 32) are the same as the cross-sectional positions in Figure 7, which shows the main parts of the thermal printhead A10.

First, a convex portion 17 is formed on a substrate 81 as shown in Figures 13 and 14.

13, a first mask layer 891 is formed to cover the substrate 81. The substrate 81 is made of a semiconductor material. The semiconductor material includes a single crystal material of silicon. The substrate 81 is a silicon wafer. A plurality of substrates 1 are connected in a direction perpendicular to the z direction to form the substrate 81. The substrate 81 has a first surface 81A and a second surface 81B. The first surface 81A and the second surface 81B face opposite each other in the z direction. The first surface 81A and the second surface 81B of the substrate 81 are both surfaces with Miller indices (100). The first mask layer 891 is formed to cover the first surface 81A and the second surface 81B. The first mask layer 891 is made of silicon nitride. In forming the first mask layer 891, a thin film of silicon nitride is first formed to cover the first surface 81A and the second surface 81B by thermal CVD (Chemical Vapor Deposition). Next, a portion of the region of the thin silicon nitride film covering the first surface 81A is removed by lithography patterning and reactive ion etching (RIE), thereby forming a first mask layer 891 that covers a portion of the first surface 81A and the second surface 81B.

Next, as shown in FIG. 14, the main surface 10 and the convex portion 17 are formed on the substrate 81. The main surface 10 and the convex portion 17 are formed by wet etching the area of the first surface 81A exposed from the first mask layer 891 shown in FIG. 13 using an aqueous potassium hydroxide (KOH) solution. The etching is anisotropic. Next, the area of the first mask layer 891 covering the first surface 81A is removed by wet etching using hydrofluoric acid (HF). As a result, the main surface 10 including the base surface 11 and the convex surface 12 and the convex portion 17 are formed on the substrate 81. The convex surface 12 bulges in the z direction from the base surface 11. The convex portion 17 bulges in the z direction from the base surface 11 and extends along the x direction. The convex portion 17 includes the convex surface 12. The area of the first surface 81A covered by the first mask layer 891 becomes the top surface 121 of the convex surface 12. Furthermore, the inclination angles α (see FIG. 8) of the pair of inclined surfaces 122 of the convex surface 12 with respect to the base surface 11 are both the same. This is because the convex portion 17 is formed by anisotropic etching.

Next, as shown in Figures 15 and 16, a first recess 811 is formed in the substrate 81, recessed in the z direction from the base surface 11 (main surface 10).

First, as shown in FIG. 15, a second mask layer 892 is formed to cover the main surface 10 of the substrate 81. The second mask layer 892 is made of silicon nitride. To form the second mask layer 892, first, a thin film of silicon nitride is formed to cover the main surface 10 by thermal CVD. Next, a portion of the thin film of silicon nitride covering the base surface 11 is removed by lithographic patterning and reactive ion etching. This forms the second mask layer 892 that covers a portion of the main surface 10.

Next, as shown in FIG. 16, a first recess 811 is formed in the substrate 81. The first recess 811 is formed by wet etching the area of the base surface 11 exposed from the second mask layer 892 shown in FIG. 15 using an aqueous potassium hydroxide solution. The etching is anisotropic. Finally, the second mask layer 892 is removed by wet etching using hydrofluoric acid. In this manner, the first recess 811 is formed in the substrate 81. Furthermore, a first inner circumferential surface 181 that defines the first recess 811 is formed in the substrate 81.

17 and 18, a plurality of second recesses 812 recessed in the z direction from the base surface 11 (principal surface 10) are formed in the substrate 81. The second recesses 812 are located on the opposite side of the first recesses 811 in the y direction with respect to the heating portions 31 of the resistor layer 3 shown in FIG.

First, as shown in FIG. 17, a third mask layer 893 is formed to cover the main surface 10 and the first inner peripheral surface 181 of the substrate 81. The third mask layer 893 is made of silicon nitride. To form the third mask layer 893, first, a thin film of silicon nitride is formed by thermal CVD to cover the main surface 10 and the first inner peripheral surface 181. Next, a portion of the thin film of silicon nitride covering the base surface 11 is removed by lithographic patterning and reactive ion etching. This forms the third mask layer 893 that covers a portion of the main surface 10 and the first inner peripheral surface 181.

Next, as shown in FIG. 18, a plurality of second recesses 812 are formed in the substrate 81. The plurality of second recesses 812 are formed by deep RIE in each of a plurality of regions of the base surface 11 exposed from the third mask layer 893 shown in FIG. 17. Finally, the third mask layer 893 is removed by wet etching using hydrofluoric acid. In this manner, a plurality of second recesses 812 are formed in the substrate 81. Furthermore, a plurality of second inner circumferential surfaces 191 that individually define the plurality of second recesses 812 are formed in the substrate 81.

19, a first insulating layer 21 is formed to cover the main surface 10, the first inner peripheral surface 181, and the plurality of second inner peripheral surfaces 191 of the base material 81. The first insulating layer 21 is formed by laminating thin films of TEOS- _SiO2 multiple times by plasma CVD.

20 to 24, the resistor layer 3 and the wiring layer 4 are formed. The resistor layer 3 includes a plurality of heat generating parts 31 arranged in the x direction. The wiring layer 4 is electrically connected to the plurality of heat generating parts 31. Furthermore, the process of forming the wiring layer 4 includes a process of forming a common wiring 41, a plurality of individual wirings 42, a first through wiring 511, and a plurality of second through wirings 512. In the substrate 81, the common wiring 41 is located on one side (downstream side) in the y direction with respect to the plurality of heat generating parts 31 of the resistor layer 3 shown in FIG. 24. In the substrate 81, the plurality of individual wirings 42 are located on the other side (upstream side) in the y direction with respect to the plurality of heat generating parts 31 shown in FIG. 24. The first through wiring 511 is accommodated in the first recess 811 of the substrate 81 and is connected to the common wiring 41. The second through wiring 512 is individually accommodated in the plurality of second recesses 812 of the substrate 81 and is individually connected to the plurality of individual wirings 42.

20, a resistor film 82 is formed on the main surface 10 of the substrate 81, in the first recess 811 of the substrate 81, and in the multiple second recesses 812. The resistor film 82 is formed so as to cover the entire surface of the first insulating layer 21. The resistor film 82 is formed by laminating a thin film of tantalum nitride on the first insulating layer 21 by a sputtering method.

21, a conductive layer 83 is formed to cover the entire surface of the resistor film 82. The conductive layer 83 is formed by laminating multiple copper thin films on the resistor film 82 by a sputtering method. Alternatively, the conductive layer 83 may be formed by laminating a titanium thin film on the resistor film 82 by a sputtering method, and then laminating multiple copper thin films on the titanium thin film by a sputtering method. As a result, the base layer 511A of the first through wiring 511 is formed in the first recess 811 of the substrate 81. Furthermore, multiple second through wirings 512 are individually formed in the multiple second recesses 812 of the substrate 81.

22, a main body layer 511B of the first through wiring 511 is formed in the first recess 811 of the substrate 81. The main body layer 511B is made of copper. The main body layer 511B is formed by subjecting the conductive layer 83 to lithographic patterning and then electrolytic plating using the conductive layer 83 as a conductive path. As a result, the first through wiring 511 is formed in the first recess 811.

23, the conductive layer 83 is lithographically patterned, and then a portion of the conductive layer 83 is removed. The removal is performed by wet etching using a mixed solution of sulfuric acid ( _{H2SO4 )} and hydrogen peroxide ( _H2O2 ). As a result, the common wiring 41 and the multiple individual wirings 42 are formed on the resistor film _82. Thus, the formation of the wiring layer 4 is completed by this process. Furthermore, the region of the resistor film 82 formed on the top surface 121 (convex surface 12) of the substrate 81 is exposed from the wiring layer 4.

24, lithographic patterning is performed on the resistor film 82, the wiring layer 4, and the main layer 511B of the first through wiring 511, and then a portion of the resistor film 82 is removed. The removal is performed by reactive ion etching. As a result, the resistor layer 3 is formed on the main surface 10 of the substrate 81, in the first recess 811 of the substrate 81, and in the multiple second recesses 812. Multiple heat generating portions 31 are formed on the top surface 121 of the substrate 81.

25, a protective layer 6 is formed to cover the main surface 10 of the substrate 81, a portion of each of the first through wirings 511, the heating portions 31 of the resistor layer 3, and the wiring layer 4. The protective layer 6 is formed by laminating a thin film of silicon nitride by plasma CVD.

26, a part of the substrate 81 located on the opposite side to the main surface 10 in the z direction is removed. The removal is performed by polishing. Furthermore, the removal is performed until a part of the first through wiring 511 and a part of each of the plurality of second through wirings 512 are exposed from the substrate 81. As a result, a part of the substrate 81 including the second surface 81B and an area of the first mask layer 891 covering the second surface 81B are removed. Furthermore, the substrate 81 has a back surface 13 facing the opposite side to the main surface 10 in the z direction. A part of the first through wiring 511 and a part of each of the plurality of second through wirings 512 are exposed from the back surface 13. Furthermore, a part of each of the first insulating layer 21 and the resistor layer 3 is exposed from the back surface 13. Through this process, the first recess 811 of the substrate 81 becomes the first through portion 18. In addition, the plurality of second recesses 812 of the substrate 81 become the plurality of second through portions 19.

27, a second insulating layer 22 is formed to cover the rear surface 13 of the substrate 81. The second insulating layer 22 is made of silicon nitride. The second insulating layer 22 is formed with a first opening 221 penetrating in the z-direction and a plurality of second openings 222. In forming the second insulating layer 22, first, a thin film of silicon nitride covering the rear surface 13 is formed by plasma CVD. Then, a part of the thin film of silicon nitride covering the rear surface 13 is removed by lithography patterning and reactive ion etching. As a result, the second insulating layer 22 covering the rear surface 13 is formed, and the first opening 221 and a plurality of second openings 222 are formed in the second insulating layer 22. As shown in FIGS. 28 and 29, the second insulating layer 22 is connected to the first insulating layer 21 at the boundaries between the first inner peripheral surface 181 and the plurality of second inner peripheral surfaces 191 of the substrate 81 and the rear surface 13. 28 , a part of the resistor layer 3 and a part of the base layer 511A of the first through wiring 511 are exposed from the first opening 221. As shown in FIG 29 , a part of the resistor layer 3 and a part of each of the plurality of second through wirings 512 are exposed from any of the plurality of second openings 222.

Next, as shown in Figures 28 to 33, electrodes (a first electrode 521 and multiple second electrodes 522) and a heat dissipation layer 53 are formed. The first electrode 521 is electrically connected to the common wiring 41. The multiple second electrodes 522 are individually electrically connected to the multiple individual wirings 42. The first electrode 521, the multiple second electrodes 522, and the heat dissipation layer 53 are arranged on the rear surface 13 of the substrate 81 and in contact with the second insulating layer 22. That is, the first electrode 521, the multiple second electrodes 522, and the heat dissipation layer 53 are located on the opposite side of the substrate 81 to the wiring layer 4 in the z direction.

First, as shown in Figures 28 and 29, a base layer 84 is formed to cover the second insulating layer 22. The base layer 84 is formed by laminating a thin film of titanium on the second insulating layer 22 by a sputtering method, and then laminating a thin film of copper on the thin film of titanium by a sputtering method. As a result, the base layer 84 is also formed in the first opening 221 of the second insulating layer 22 and the multiple second openings 222 of the second insulating layer 22. The base layer 84 formed in the first opening 221 contacts the resistor layer 3 and the base layer 511A of the first through wiring 511. The base layer 84 formed in the multiple second openings 222 contacts the resistor layer 3 and the multiple second through wirings 512.

30 to 32, a plurality of main body layers 85 are formed on the base layer 84. The plurality of main body layers 85 are made of copper. The plurality of main body layers 85 are formed by subjecting the base layer 84 to lithographic patterning and then performing electrolytic plating using the base layer 84 as a conductive path.

33, the areas of the base layer 84 that are not covered by the plurality of main body layers 85 are removed by wet etching using a mixed solution of sulfuric acid and hydrogen peroxide. This results in the formation of the first electrode 521, the plurality of second electrodes 522, and the heat dissipation layer 53.

Next, the substrate 81 is cut along the x-direction and the y-direction to divide the substrate 81 into individual pieces. This results in the main part of the thermal printhead A10 including the substrate 1. Next, a plurality of driving elements 73 and a connector 77 are mounted on the wiring board 71, a plurality of first wires 74 and a plurality of second wires 75 are joined, and a sealing resin 76 is formed. Next, the heat dissipation layer 53 is joined to the heat sink 711 of the wiring board 71, and the first electrode 521 and a plurality of second electrodes 522 are joined to the wiring 712 of the wiring board 71. Finally, the wiring board 71 is joined to the heat sink 72. Through the above steps, the thermal printhead A10 is obtained.

Next, the effects of the thermal print head A10 will be explained.

The thermal printhead A10 has a main surface 10 and a back surface 13, and includes a substrate (semiconductor substrate) 1 made of a semiconductor material, a wiring layer 4 formed on the resistor layer 3, and a first electrode 521 formed on the back surface 13. The wiring layer 4 includes a common wiring 41 located on one side (downstream side) in the y direction with respect to the multiple heat generating parts 31 of the resistor layer 3. On the other hand, a first through portion 18 is formed in the substrate 1, penetrating from the main surface 10 to the back surface 13. The first through portion 18 contains a first through wiring 511. The first through wiring 511 is connected to the common wiring 41 and the first electrode 521. With this configuration, it is possible to ensure a conduction path for the common wiring 41 in the thermal printhead A10 without widely arranging the common wiring 41 on the other side (upstream side) in the y direction with respect to the multiple heat generating parts 31 on the main surface 10. This makes it possible to increase the number of individual wirings 42 located on the other side in the y direction of the heat generating parts 31 without increasing the area of the main surface 10, thereby making it possible to increase the number of heat generating parts 31 while reducing the width (length in the x direction) of each of the heat generating parts 31. Therefore, the thermal printhead A10 makes it possible to perform finer printing without increasing the size of the substrate 1.

In the thermal printhead A10, since it is required to more quickly pass the current flowing from the multiple heat generating parts 31 to the common wiring 41, the thickness of the common wiring 41 is made larger than the thickness of each of the multiple individual wirings 42. Therefore, by providing the thermal printhead A10 with the first through wiring 511 and the first electrode 521, the area of the common wiring 41 when viewed along the z direction can be further reduced. This makes it possible to suppress warping of the substrate 1 in the z direction caused by the difference between the linear expansion coefficient of the substrate 1 and the linear expansion coefficient of the wiring layer 4.

The thermal printhead A10 further includes a plurality of second electrodes 522 formed on the rear surface 13 of the substrate 1. On the other hand, the substrate 1 is formed with a plurality of second through-holes 19 that penetrate from the main surface 10 to the rear surface 13 and are located on the opposite side of the first through-holes 18 with respect to the plurality of heat generating parts 31 in the y direction. The plurality of second through-holes 19 individually accommodate a plurality of second through-hole wirings 512. Each of the plurality of second through-hole wirings 512 is connected to one of the plurality of individual wirings 42 and one of the plurality of second electrodes 522. As a result, in the substrate 1, the plurality of second electrodes 522 and the first electrode 521 are formed at the same position in the z direction. Therefore, it is possible to avoid the structure of the wiring substrate 71 to which the plurality of second electrodes 522 and the first electrode 521 are joined being complicated.

The main surface 10 of the substrate 1 includes a base surface 11 and a convex surface 12 that bulges out from the base surface 11 in the z direction. The convex surface 12 extends along the x direction. The multiple heat generating portions 31 are formed on the convex surface 12. This makes it possible to reduce the contact area of the thermal printhead A10 with the recording medium 78 (see FIG. 6) when the thermal printhead A10 is in use. This makes it possible to improve the quality of printing on the recording medium 78 caused by the multiple heat generating portions 31.

Furthermore, the convex surface 12 includes a top surface 121 parallel to the base surface 11 of the substrate 1, and a pair of inclined surfaces 122 connected to the top surface 121 and the base surface 11 and positioned apart from each other in the y direction. The plurality of heat generating parts 31 are formed on the top surface 121. A part of the common wiring 41 and a part of each of the plurality of individual wirings 42 are formed on one of the pair of inclined surfaces 122. This makes it possible to further reduce the size of each of the plurality of heat generating parts 31 in the y direction when viewed along the z direction, while further reducing the contact area of the recording medium 78 with the thermal printhead A10 when using the thermal printhead A10. Therefore, the amount of heat generated in the thermal printhead A10 can be suppressed, and the quality of printing on the recording medium 78 can be further improved.

In the substrate 1, the pair of inclined surfaces 122 are inclined with respect to the base surface 11 so as to approach each other from the base surface 11 to the top surface 121. Such a shape of the convex surface 12 is obtained by forming the convex portion 17 in the base material 81 by anisotropic etching in the manufacturing method of the thermal printhead A10. This is because the semiconductor material constituting the base material 81 contains a single crystal silicon material.

The thermal printhead A10 further includes a first insulating layer 21 and a second insulating layer 22. The first insulating layer 21 covers the main surface 10 of the substrate 1 as well as the first inner peripheral surface 181 that defines the first through-hole 18 and the second inner peripheral surfaces 191 that define each of the second through-holes 19. The second insulating layer 22 covers the rear surface 13 of the substrate 1 and is connected to the first insulating layer 21. As a result, even if the thermal printhead A10 includes the first through-hole wiring 511, the second through-hole wirings 512, the first electrode 521, and the second electrodes 522, these conductive elements can be electrically insulated from the substrate 1. Therefore, in the wiring layer 4, a short circuit between the common wiring 41 and the individual wirings 42 is prevented.

The thermal printhead A10 further includes a heat dissipation layer 53 located between the first electrode 521 and the multiple second electrodes 522 in the y direction and formed in contact with the second insulating layer 22. When viewed along the z direction, the heat dissipation layer 53 overlaps the multiple heat generating parts 31. This allows a portion of the heat generated from the multiple heat generating parts 31 to be rapidly conducted from the substrate 1 to the heat dissipation layer 53 when the thermal printhead A10 is in use.

The thermal printhead A10 further includes a wiring board 71 to which a first electrode 521 and a plurality of second electrodes 522 are bonded. The wiring board 71 has a heat sink 711 to which the heat dissipation layer 53 is bonded. As a result, in the above-mentioned case, the heat conducted to the heat dissipation layer 53 is quickly released to the outside via the heat sink 711.

A thermal printhead A20 according to a second embodiment of the first aspect of the present disclosure will be described with reference to Figures 34 and 35. In these figures, elements that are the same as or similar to those of the thermal printhead A10 described above are given the same reference numerals, and duplicated descriptions will be omitted. Here, the cross-sectional position in Figure 34 is the same as the cross-sectional position in Figure 6 showing the thermal printhead A10 described above.

In thermal printhead A20, the configuration of the convex surface 12 of the substrate 1 differs from that of the thermal printhead A10 described above.

34 and 35, each of the pair of inclined surfaces 122 of the convex surface 12 includes a first region 122A and a second region 122B. The first region 122A is connected to the base surface 11 of the substrate 1. The second region 122B is connected to the top surface 121 of the convex surface 12 and the first region 122A. In each of the pair of inclined surfaces 122, the inclination angle α2 of the second region 122B with respect to the base surface 11 is smaller than the inclination angle α1 of the first region 122A with respect to the base surface 11.

Next, the effects of the thermal print head A20 will be explained.

The thermal printhead A20 has a main surface 10 and a back surface 13, and includes a substrate (semiconductor substrate) 1 made of a semiconductor material, a wiring layer 4 formed on the resistor layer 3, and a first electrode 521 formed on the back surface 13. The wiring layer 4 includes a common wiring 41 located on one side in the y direction with respect to the multiple heat generating portions 31 of the resistor layer 3. On the other hand, the substrate 1 is formed with a first through portion 18 that penetrates from the main surface 10 to the back surface 13. The first through portion 18 contains a first through wiring 511. The first through wiring 511 is connected to the common wiring 41 and the first electrode 521. Therefore, the thermal printhead A20 also makes it possible to perform finer printing without increasing the size of the substrate 1.

In the thermal printhead A20, each of the pair of inclined surfaces 122 (convex surface 12) of the substrate 1 includes a first region 122A and a second region 122B. The first region 122A is connected to the base surface 11 of the substrate 1. The second region 122B is connected to the top surface 121 of the convex surface 12 and the first region 122A. In each of the pair of inclined surfaces 122, the inclination angle α2 of the second region 122B with respect to the base surface 11 is smaller than the inclination angle α1 of the first region 122A with respect to the base surface 11. By adopting this configuration, the surface of the protective layer 6 formed along the convex surface 12 becomes smoother. Therefore, when the recording medium 78 shown in FIG. 6 contacts the protective layer 6 during use of the thermal printhead A20, the kinetic friction force of the recording medium 78 with respect to the protective layer 6 is reduced, so that, first, the adhesion of paper shavings caused by the recording medium 78 to the protective layer 6 can be suppressed. Secondly, the wear of the protective layer 6 is suppressed, thereby extending the life of the thermal printhead A20.

The present disclosure is not limited to the embodiment relating to the first aspect described above. The specific configuration of each part of the present disclosure can be freely designed in various ways.

[Explanation of symbols according to the first aspect of the embodiment]
A10, A20: Thermal print head 1: Substrate
10: Principal surface 11: Base surface 12: Convex surface 121: Top surface 122: Inclined surface 122A: First region 122B: Second region 13: Back surface 17: Convex portion 18: First penetrating portion 181: First inner circumferential surface 19: Second penetrating portion 191: Second inner circumferential surface 21: First insulating layer 22: Second insulating layer 221: First opening 222: Second opening 3: Resistor layer 31: Heat generating part 4: Wiring layer 41: Common wiring 411: Base 412: Extension 42: Individual wiring 421: Base 422: Extension 511: First through wiring 511A: Base layer 511B: Main body layer 512: Second through wiring 521: First electrode 521A: Base layer 521B: main layer 522: second electrode 522A: underlayer 522B: main layer 53: heat dissipation layer 53A: underlayer 53B: main layer 6: protective layer 71: wiring board 711: heat dissipation body 712: wiring 72: heat sink 73: driving element 74: first wire 75: second wire 76: sealing resin 77: connector 78: recording medium 79: platen roller 81: substrate 81A: first surface 81B: second surface 811: first recess 812: second recess 82: resistor film 83: conductive layer 84: underlayer 85: main layer 891: first mask layer 892: second mask layer 893: third mask layer α, α1, α2: inclination angle

Next, an embodiment relating to the second aspect of the present disclosure will be described with reference to Figures 36 to 56. The reference numbers used in Figures 36 to 56 (second aspect) are unrelated to the reference numbers used in Figures 1 to 35 (first aspect), and the same reference numbers may refer to different components, and different reference numbers may refer to the same or similar components. This unrelated nature of the reference numbers used in the drawings relating to different aspects also applies to the drawings explaining the embodiments relating to the third and fourth aspects described below.

In the conventional thermal printhead disclosed in Patent Document 1, there can be various types of print lengths in the main scanning direction. In order to manufacture thermal printheads with different print lengths in the main scanning direction, it is necessary to divide a Si wafer into multiple types of individual pieces with different lengths. There is a concern that the efficiency of manufacturing thermal printheads from a Si wafer will decrease as the number of types of thermal printheads with different print lengths increases. Therefore, an objective of the second aspect of the present disclosure is to provide a technology that can improve the manufacturing efficiency of thermal printheads with various different print lengths in the main scanning direction.

Figures 36 to 39 show a thermal printhead according to one embodiment of the second aspect. The thermal printhead B10 of this embodiment comprises a head substrate 1, a wiring substrate 5, multiple wires 61, 62, 63, multiple driving ICs 7, a resin part 78, a heat dissipation member 81 and a support member 82. The thermal printhead B10 is incorporated into a printer that prints on a print medium (not shown) transported by a platen roller 99 (see Figure 39). Examples of print media include thermal paper for producing barcode sheets and receipts.

Figure 36 is a plan view showing thermal printhead B10. Figure 37 is a cross-sectional view taken along line 037-037 in Figure 36. Figure 38 is a cross-sectional view of a main portion of thermal printhead B10, and is an enlarged cross-sectional view of a portion of Figure 39. Figure 39 is an enlarged plan view of a main portion of thermal printhead B10. For ease of understanding, protective layer 2 has been omitted from Figures 36 and 39. For ease of understanding, resin portion 78 has been omitted from Figures 36 and 39.

As shown in Figure 37, in the thermal printhead B10, the head substrate 1 and wiring substrate 5 are mounted adjacent to each other in the y direction on a heat dissipation member 81. In this embodiment, the head substrate 1 is supported on the heat dissipation member 81 via a support member 82. The head substrate 1 has a plurality of heat generating portions 41 arranged in the y direction (described later). The heat generating portions 41 are selectively driven to generate heat by a drive IC 7 mounted on the wiring substrate 5, and print on a print medium pressed against the heat generating portions 41 by a platen roller 99 in accordance with a print signal transmitted from the outside via a connector 59.

As shown in Figures 36, 38 and 39, the head substrate 1 has a base material 10, an insulating layer 19, a protective layer 2, an electrode layer 3 and a resistor layer 4.

The substrate 10 is made of a Si single crystal semiconductor. A suitable material for the substrate 10 is, for example, a Si wafer. As shown in FIG. 36, the substrate 10 has an elongated rectangular shape with the x direction as the long side and the y direction as the short side when viewed in the z direction. The substrate 10 is composed of a plurality of individual chips 10A. The plurality of individual chips 10A are lined up in the x direction.

The individual chip 10A has a first side 101 and a second side 102. The second side 102 is an end face facing one side in the x direction (one side in the main scanning direction). The first side 101 is an end face facing the other side in the x direction (the other side in the main scanning direction).

In this embodiment, a pair of individual chips 10A adjacent in the x direction are in close contact with each other. The first side 101 of the individual chip 10A located on one side in the x direction (one side in the main scanning direction) of the pair of individual chips 10A adjacent in the x direction is perpendicular to the x direction. Also, the second side 102 of the individual chip 10A located on the other side in the x direction (the other side in the main scanning direction) of the pair of individual chips 10A adjacent in the x direction is perpendicular to the x direction. In a pair of individual chips 10A adjacent in the x direction, the first side 101 of the individual chip 10A located on one side in the x direction and the second side 102 of the individual chip 10A located on the other side in the x direction are in close contact with each other.

The size of the substrate 10 (multiple individual chips 10A arranged in the x direction) is not limited, but as an example, the dimension in the x direction is, for example, about 50 mm to 400 mm, the dimension in the y direction is, for example, about 3 mm to 10 mm, and the dimension in the z direction is, for example, about 725 μm. As an example of the dimensions of the individual chips 10A, the dimension in the x direction is, for example, about 5 mm to 15 mm. In the substrate 10, the side closer to the driving IC 7 in the y direction is the upstream side, and the side farther from the driving IC 7 is the downstream side. The printing medium is transported from the upstream side to the downstream side in the y direction by the platen roller 99.

As shown in Figures 37 to 39, the substrate 10 (each individual chip 10A) has a main surface 11 and a convex portion 12. The main surface 11 faces upward in the z direction. In this disclosure, the main surface 11 spreads along the x-y plane (a plane defined by the x and y directions, the same applies to other planes) and is a plane that is approximately parallel to the x-y plane. The main surface 11 is a plane with Miller indices (100). The convex portion 12 protrudes from the main surface 11 in the z direction and extends in the x direction. The convex portion 12 is formed toward the downstream side of the main surface 11. The shape of the cross section of the convex portion 12 along the y-z plane is uniform in the x direction. The dimension of the convex portion 12 in the y direction at the end on the lower side in the z direction is, for example, about 500 μm, and the dimension of the y direction at the end on the upper side in the z direction (top surface 121 described later) is, for example, about 200 μm. The dimension of the protrusion 12 in the z direction is, for example, about 150 μm.

38, the convex portion 12 has a top surface 121 and a pair of inclined surfaces 122. The top surface 121 is parallel to the main surface 11 and is substantially flat. When viewed in the z direction, the top surface 121 is an elongated rectangular shape extending long in the x direction. The dimension of the convex portion 12 in the z direction is the distance between the top surface 121 and the main surface 11 in the z direction. The pair of inclined surfaces 122 sandwich the top surface 121 in the y direction. In addition, each of the pair of inclined surfaces 122 is connected to the main surface 11 and the top surface 121, and is sandwiched between them in the y direction. Each inclined surface 122 is inclined with respect to the main surface 11 and the top surface 121 so that it is lower as it moves away from the top surface 121 in the y direction. In other words, the pair of inclined surfaces 122 approach each other in the y direction as it moves away from the main surface 11 in the z direction. Each inclined surface 122 is substantially flat. The inclination angle of each inclined surface 122 with respect to the main surface 11 is, for example, 54.8 degrees. Each inclined surface 122 is a (111) surface.

In this embodiment, the convex portion 12 is arranged on each of the multiple individual chips 10A. The positions of the convex portions 12 in the y direction are aligned on each of the multiple individual chips 10A. As a result, the convex portions 12 on each of the multiple individual chips 10A overlap when viewed in the x direction.

As shown in FIG. 38, the insulating layer 19 is formed on the main surface 11 of the substrate 10 and covers the substrate 10 (each chip 10A). The insulating layer 19 contacts the main surface 11, the top surface 121 of the protrusion 12, and the pair of inclined surfaces 122. The insulating layer 19 is for more reliably insulating the substrate 10 (each chip 10A) from the resistor layer 4 and the electrode layer 3. The insulating layer 19 may be formed in the region of the substrate 10 (each chip 10A) where the resistor layer 4 or the electrode layer 3 is formed. The insulating layer 19 is made of an insulating material, for example, SiO ₂ or SiN (silicon nitride), and preferably TEOS-SiO ₂ (SiO ₂ formed using TEOS (tetraethyl orthosilicate) as a raw material). The thickness of the insulating layer 19 is not particularly limited, and is, for example, 1 μm or more and 10 μm or less.

As shown in FIG. 38, the resistor layer 4 is formed on the insulating layer 19 and supported by the substrate 10 (multiple individual chips 10A). The resistor layer 4 is formed across the main surface 11 and the protrusions 12, sandwiching the insulating layer 19. The resistor layer 4 is made of, for example, TaN (tantalum nitride). The thickness of the resistor layer 4 is not particularly limited, and is, for example, 0.02 μm or more and 0.1 μm or less (preferably about 0.08 μm). In this embodiment, the resistor layer 4 is arranged separately corresponding to each of the multiple individual chips 10A.

As shown in Figures 36, 38 and 39, the resistor layer 4 includes a plurality of heat generating portions 41. The plurality of heat generating portions 41 are exposed portions of the resistor layer 4 that are not covered by the electrode layer 3 described below. The plurality of heat generating portions 41 are selectively energized to locally heat the print medium. The plurality of heat generating portions 41 are arranged in the x direction and are spaced apart from one another in the x direction. The formation area of the plurality of heat generating portions 41 in the y direction is an area that includes part or all of the top surface 121 of the protrusion 12 in the y direction.

36 and 39, a plurality of heat generating portions 41 are arranged on each of the plurality of individual chips 10A. In this embodiment, the plurality of heat generating portions 41 arranged on the substrate 10 are arranged at a constant pitch in the x direction across all of the plurality of individual chips 10A. The boundary between a pair of adjacent individual chips 10A in the x direction is located between a pair of heat generating portions 41 adjacent to each other in the x direction.

The electrode layer 3 forms a conductive path for passing electricity through the multiple heat generating parts 41. The electrode layer 3 is laminated on the resistor layer 4 and supported by the substrate 10 (multiple individual chips 10A). The electrode layer 3 is made of a metal material having a smaller resistance value than the resistor layer 4, for example, Cu (copper). The thickness of the electrode layer 3 is not particularly limited, and is, for example, 0.3 μm or more and 2.0 μm or less. The electrode layer 3 may be configured by laminating a Cu layer and a Ti (titanium) layer. In this case, the Ti layer is interposed between the Cu layer and the resistor layer 4, and has a thickness of, for example, about 100 nm. In this embodiment, the electrode layer 3 is arranged separately corresponding to each of the multiple individual chips 10A.

In this embodiment, as shown in FIG. 39, the electrode layer 3 in each individual chip 10A includes a plurality of individual electrodes 31, a common electrode 32, and a plurality of relay electrodes 33.

The common electrode 32 has a plurality of common electrode extensions 321, a plurality of branch portions 322, and a main portion 323. The common electrode extensions 321 are strip-shaped extending along the y direction. The common electrode extensions 321 are arranged upstream in the y direction from the heat generating portion 41. The common electrode extensions 321 are arranged at predetermined intervals in the x direction (main scanning direction).

A pair of branched portions 322 are connected to the downstream end of each common electrode extension 321 in the y direction. The branched portions 322 are strip-shaped extending in the y direction. The downstream end of each branched portion 322 in the y direction extends up to the inclined surface 122 on the upstream side in the y direction. The pair of branched portions 322 connected to the common electrode extension 321 are spaced apart from each other in the x direction and are in contact with a pair of adjacent heat generating portions 41 in the x direction. As a result, each common electrode extension 321 is electrically connected to a pair of adjacent heat generating portions 41 in the x direction via the pair of branched portions 322. The main portion 323 is strip-shaped extending in the x direction and is disposed closer to the driving IC 7 in the y direction. The upstream end of each common electrode extension 321 in the y direction is connected to the main portion 323.

The multiple individual electrodes 31 are separated from each other in the x direction. The individual electrodes 31 are arranged upstream in the y direction from the heat generating portion 41. Each individual electrode 31 has an individual electrode extension portion 311 and an electrode pad portion 312. The individual electrode extension portion 311 is strip-shaped extending generally along the y direction. The downstream end of the individual electrode extension portion 311 in the y direction extends onto the inclined surface 122 on the upstream side in the y direction and contacts the heat generating portion 41. The electrode pad portion 312 is connected to the upstream end of the individual electrode extension portion 311 in the y direction. The electrode pad portion 312 is the portion to which the wire 61 is bonded.

Each individual electrode extension portion 311 is spaced apart from the common electrode extension portion 321 in the x direction. The individual electrode extension portions 311 are adjacent to each common electrode extension portion 321 on both sides in the x direction. In other words, each common electrode extension portion 321 is sandwiched between two individual electrode extension portions 311 adjacent to each other on both sides in the x direction.

The heat generating portion 41 in contact with the individual electrode extension portion 311 is adjacent to the heat generating portion 41 that is conductive to the common electrode extension portion 321. More specifically, the heat generating portion 41 in contact with one of the two individual electrode extension portions 311 that sandwich the common electrode extension portion 321 is adjacent to one of the pair of heat generating portions 41 that are conductive to the common electrode extension portion 321. The heat generating portion 41 in contact with the other of the two individual electrode extension portions 311 that sandwich the common electrode extension portion 321 is adjacent to the other of the pair of heat generating portions 41 that are conductive to the common electrode extension portion 321.

The multiple relay electrodes 33 are arranged along the x direction. The multiple relay electrodes 33 are arranged downstream in the y direction from the multiple heat generating portions 41, and are located on the opposite side in the y direction from the common electrode 32 and the multiple individual electrodes 31, sandwiching the multiple heat generating portions 41 between them. Each relay electrode 33 is in contact with a pair of heat generating portions 41 adjacent to each other in the x direction. Each of the multiple relay electrodes 33 is electrically interposed between one of the multiple individual electrodes 31 and the common electrode 32. Each relay electrode 33 has a pair of relay electrode extension portions 331 and a connecting portion 332.

38 and 39, each relay electrode extension 331 is a strip extending in the y direction. The multiple relay electrode extensions 331 are spaced apart from each other in the x direction. The upstream end of each relay electrode extension 331 in the y direction extends to the inclined surface 122 downstream in the y direction. Each pair of relay electrode extensions 331 constituting each relay electrode 33 is in contact with a pair of adjacent heat generating portions 41 in the x direction. One of the pair of relay electrode extensions 331 in each relay electrode 33 is disposed opposite one of the multiple branch portions 322 in the y direction, sandwiching the heat generating portion 41 therebetween. The other of the pair of relay electrode extensions 331 in each relay electrode 33 is disposed opposite one of the multiple individual electrode extensions 311 in the y direction, sandwiching the heat generating portion 41 therebetween.

Each connecting portion 332 extends along the x direction. Each connecting portion 332 is connected to a pair of relay electrode extension portions 331 in each relay electrode 33. This allows the pair of relay electrode extension portions 331 in each relay electrode 33 to be electrically connected to each other.

A specific configuration example of the electrode layer 3 (multiple individual electrodes 31 and common electrode 32) has been described with reference to Figure 39, but the shapes of each individual electrode 31 and common electrode 32 when viewed in the z direction, i.e., the formation areas of each individual electrode 31 and common electrode 32, are not limited to the example shown in Figure 39.

As shown in Fig. 38, the protective layer 2 covers the electrode layer 3 and the resistor layer 4. The protective layer 2 is made of an insulating material, for example, _SiO2 , SiN, SiC (silicon carbide), AlN (aluminum nitride), or a laminate of two or more of these. The thickness of the protective layer 2 is not particularly limited, and is, for example, 1.0 µm or more and 10 µm or less. The protective layer 2 has a pad opening 21 that penetrates in the z direction. The pad opening 21 exposes each of the electrode pad portions 312 provided on the multiple individual electrodes 31.

As shown in Figures 36 and 37, the wiring board 5 is disposed adjacent to the head board 1 on the upstream side in the y direction. The wiring board 5 is, for example, a PCB board. As shown in Figure 36, the wiring board 5 has an elongated rectangular shape with the x direction as the longitudinal direction when viewed in the z direction. A wiring pattern (detailed shape is not shown) is formed on the wiring board 5. As shown in Figure 39, the wiring pattern includes an individual wiring portion 51 and a common wiring portion 52. As shown in Figure 37, a connector 59 and a driving IC 7 are mounted on the wiring board 5.

The connector 59 is used to connect the thermal print head B10 to a printer (not shown). The connector 59 is attached to the wiring board 5 and connected to the wiring pattern of the wiring board 5, as shown in FIG.

The driving IC 7 is arranged on the wiring substrate 5 as shown in Figures 36 and 37. The driving IC 7 applies a potential to each individual electrode 31 and controls the current flowing through each heat generating portion 41. As shown in Figure 36, in this embodiment, multiple driving ICs 7 are mounted on the wiring substrate 5. The multiple driving ICs 7 are arranged at intervals in the x direction. The multiple driving ICs 7 are arranged such that, for example, one driving IC 7 is assigned to two individual chips 10A adjacent in the x direction.

As shown in Figure 39, the driving IC 7 has a plurality of pad portions 71. The plurality of pad portions 71 are formed, for example, in two rows.

The multiple wires 61, 62, and 63 shown in FIG. 39 are made of a conductor such as Au. The wire 61 is bonded to a pad portion 71 of the driving IC 7 and to an electrode pad portion 312 of the individual electrode 31. This provides electrical continuity between the driving IC 7 and each individual electrode 31. The wire 61 also spans the main part 323. The wire 62 is bonded to a pad portion 71 of the driving IC 7 and to an individual wiring portion 51 of the wiring board 5. This provides electrical continuity between the driving IC 7 and the connector 59 via the individual wiring portion 51. The wire 63 is bonded to the common electrode 32 (main part 323) and to the common wiring portion 52 of the wiring board 5. This provides electrical continuity between the common electrode 32 and the common wiring portion 52.

A print signal, a control signal, and a voltage supplied to the plurality of heat generating elements 41 are input to the driving IC 7 from the outside via the connector 59. The plurality of heat generating elements 41 are selectively heated by being individually energized in accordance with the print signal and the control signal.

The resin part 78 is made of, for example, black resin. As shown in Figures 37 and 38, the resin part 78 is formed so as to straddle the head substrate 1 and the wiring substrate 5. The resin part 78 covers the driving IC 7, the multiple wires 61, 62, 63, and a part of the protective layer 2, and protects the driving IC 7 and the multiple wires 61, 62, 63.

36 and 37, the heat dissipation member 81 supports the head substrate 1 (substrate 10, multiple individual chips 10A) and the wiring substrate 5. The heat dissipation member 81 is provided to dissipate some of the heat generated by the multiple heat generating parts 41 to the outside. The heat dissipation member 81 is made of a metal such as aluminum.

36 and 37, the support member 82 is disposed on the heat dissipation member 81 and is interposed between the head substrate 1 (substrate 10, multiple individual chips 10A) and the heat dissipation member 81. In this embodiment, the multiple individual chips 10A are bonded to the support member 82. The support member 82 is made of a plate material with high flatness, such as a Si plate.

Next, an example of a method for manufacturing the thermal printhead B10 will be described below with reference to Figures 40 to 49. Figures 40 to 45 are cross-sectional views showing a step in the method for manufacturing the thermal printhead B10, and correspond to the partially enlarged cross-section shown in Figure 38.

First, as shown in FIG. 40, a substrate 10' is prepared. The substrate 10' is made of a Si single crystal semiconductor, for example a Si wafer. The substrate 10' has a main surface 11'. The main surface 11' is substantially flat and faces upward in the z direction. The main surface 11' is a (100) plane.

Next, as shown in FIG. 41, the convex portion 12 is formed. The convex portion 12 is formed by forming a predetermined mask layer (shown by imaginary lines in FIG. 40 and FIG. 41) on a part of the main surface 11' and performing anisotropic etching on the substrate 10'. In the process of forming the convex portion 12, anisotropic etching is performed using, for example, an alkaline aqueous solution. Examples of the alkaline aqueous solution include KOH (potassium hydroxide) and TMAH (tetramethylammonium hydroxide). As a result, as shown in FIG. 41, the substrate 10 having the main surface 11 and the convex portion 12 is formed. The main surface 11 is a (100) surface like the main surface 11'. The convex portion 12 has a top surface 121 and a pair of inclined surfaces 122. Each of the pair of inclined surfaces 122 is a (111) surface and is inclined with respect to the main surface 11 and the top surface 121. The inclination angle α1 of each inclined surface 122 is, for example, 54.8 degrees.

42, the insulating layer 19 is formed by depositing TEOS-SiO ₂ using, for example, CVD. The insulating layer 19 covers the main surface 11, the pair of inclined surfaces 122 of the protrusion 12, and the top surface 121.

Next, as shown in Fig. 43, the resistor film 4' is formed. The resistor film 4' is formed, for example, by forming a thin film of TaN on the insulating layer 19 by sputtering. The resistor film 4' covers the entire surface of the insulating layer 19.

Next, as shown in FIG. 44, the electrode film 3' is formed. The electrode film 3' is formed by forming a layer made of Cu, for example, by plating or sputtering. The electrode film 3' covers the entire surface of the resistor film 4'. The electrode film 3' may be formed by forming a Ti layer on the resistor film 4' and then forming a Cu layer.

45, the electrode film 3' and the resistor film 4' are selectively etched to partially remove the electrode film 3' and the resistor film 4'. This forms the resistor layer 4 separated in the x direction and the electrode layer 3 covering the resistor layer 4 while leaving a plurality of heating portions 41. Here, the plurality of heating portions 41 are formed on the protrusions 12.

Next, as shown in FIG. 46, the substrate 10 is cut along the x-direction and y-direction to divide it into a plurality of individual chips 10A (not shown). Here, the substrate 10 is cut along a perpendicular plane C1 to the x-direction and a perpendicular plane C2 to the y-direction by laser irradiation to divide it into a plurality of individual chips 10A. More specifically, the substrate 10 is divided into individual chips 10A in a peeled manner by focusing the laser inside the substrate 10 made of a Si single crystal semiconductor. In such division into individual chips 10A by laser irradiation, there is almost no cutting width, almost no cutting waste is generated, and the cut surface is smooth.

47 and 48, in the process of dividing into a plurality of individual chips 10A by laser irradiation, the cutting of the substrate 10 on a vertical plane C1 with respect to the x direction is performed at a position between a pair of adjacent heating parts 41 in the x direction. In the formation of the resistor layer 4 and the electrode layer 3 shown in FIG. 45, the resistor layer 4 is formed separately from each other in the regions corresponding to each of the plurality of individual chips 10A, and the electrode layer 3 is formed separately from each other in the regions corresponding to each of the plurality of individual chips 10A. As a result, the resistor layer 4 and the electrode layer 3 are not formed on the cutting line of the substrate 10 (the vertical plane C1 with respect to the x direction and the vertical plane C2 with respect to the y direction shown in FIG. 47 and FIG. 48).

Next, as shown in Fig. 49, an assembly board 91 is prepared, and the support member 82 and wiring board 5 are placed on the assembly board 91. The support member 82 is, for example, a Si plate. The wiring board 5 is, for example, a PCB board. The support member 82 and wiring board 5 are temporarily fixed to the assembly board 91 via adhesive tape (not shown).

Next, as shown in FIG. 50 and FIG. 51, the plurality of chips 10A are arranged on the support member 82 along the x direction, and the back surface of the chip 10A is bonded to the upper surface of the support member 82. The chips 10A are bonded to the support member 82 using, for example, a UV adhesive. As shown in FIG. 51, the plurality of chips 10A are bonded to the support member 82 while being aligned with the wiring board 5 so that a pair of chips 10A adjacent in the x direction are in close contact with each other. In a pair of chips 10A adjacent in the x direction, the first side 101 of the chip 10A located on one side in the x direction (one side in the main scanning direction) and the second side 102 of the chip 10A located on the other side in the x direction (the other side in the main scanning direction) are in close contact with each other. In this way, the substrate 10 composed of the plurality of chips 10A is arranged on the support member 82. The plurality of heat generating parts 41 arranged on the substrate 10 are arranged at a constant pitch in the x direction across all of the plurality of chips 10A.

Next, a protective layer 2 (not shown) is formed. The protective layer 2 is formed, for example, by depositing SiN on each of the insulating layer 19, the electrode layer 3 and the resistor layer 4 on the substrate 10, for example, using CVD. In addition, the protective layer 2 having openings 21 for pads (not shown) is formed in a predetermined area on the substrate 10, for example, by using a mask. As a result of the above, the head substrate 1 arranged on the support member 82 is obtained.

Next, as shown in Figure 52, multiple drive ICs 7 are mounted on the wiring board 5. Next, multiple wires 61, 62, 63 are bonded, and a resin part 78 is formed. The support member 82, head substrate 1, and wiring board 5 are separated from the assembly board 91, and then the head substrate 1 and wiring board 5 are joined to the heat dissipation member 81, and the connector 59 is attached, etc. In this manner, the thermal printhead B10 is manufactured.

Next, the effects of this embodiment will be explained.

In the thermal printhead B10, the resistor layer 4 and the electrode layer 3 are supported by a substrate 10 made of a Si single crystal semiconductor. The resistor layer 4 includes a plurality of heat generating portions 41 arranged in the x direction (main scanning direction). The substrate 10 is configured with a plurality of individual chips 10A arranged in the x direction (main scanning direction). A plurality of heat generating portions 41 are arranged in each individual chip 10A. In addition, the boundary between a pair of adjacent individual chips 10A is located between a pair of adjacent heat generating portions 41 in the x direction (main scanning direction). This allows the plurality of heat generating portions 41 to be appropriately arranged along the x direction (main scanning direction) across all of the plurality of individual chips 10A.

In this structure in which the substrate 10 is composed of multiple individual chips 10A, the length of the substrate 10 in the x direction (main scanning direction) can be adjusted by appropriately selecting the number of individual chips 10A. This makes it possible to efficiently manufacture thermal printheads B10 with different printing lengths in the x direction (main scanning direction).

Figure 53 shows a case where the substrate 10 is composed of a larger number of individual chips 10A than in Figure 36. By using a large number of individual chips 10A in this way, the length of the substrate 10 in the x direction (main scanning direction) can be appropriately increased. Therefore, it is possible to increase the printing length in the x direction (main scanning direction) without being restricted by the size of the Si wafer that is the material of the substrate 10. Therefore, it is possible to increase the length of the thermal print head B10 in which Si is used as the substrate 10.

Figure 54 shows a case where the substrate 10 is composed of a smaller number of individual chips 10A than in Figure 36. By using a smaller number of individual chips 10A, it is possible to easily manufacture a thermal printhead B10 with a short printing length in the x direction (main scanning direction). Furthermore, by preparing individual chips 10A with a small dimension in the x direction, it is possible to set the printing length in the x direction (main scanning direction) more precisely.

Of the multiple individual chips 10A, in a pair of individual chips 10A adjacent in the x direction (main scanning direction), the first side 101 and the second side 102 facing each other in the x direction are perpendicular to the x direction. With this configuration, the multiple individual chips 10A are lined up in a straight line along the x direction (main scanning direction). In addition, the multiple heat generating parts 41 arranged on the substrate 10 are arranged at a constant pitch in the x direction (main scanning direction) across all of the multiple individual chips 10A. With the thermal printhead B10 configured in this way, it is possible to maintain appropriate printing quality.

In the manufacturing process of the thermal printhead B10, in the process of dividing the substrate 10 into a plurality of individual chips 10A, the substrate 10 is cut by laser irradiation. In the laser irradiation of the substrate 10 made of a Si single crystal semiconductor, the laser is focused inside the substrate 10, so that the substrate 10 is divided into a plurality of individual chips 10A with almost no cutting width and smooth cut surfaces. According to such a manufacturing method of the thermal printhead B10, the dimensional accuracy of the cut surface (first side surface 101 and second side surface 102) of the individual chip 10A is high, and the resistor layer 4 (heating portion 41) and the electrode layer 3 can be arranged close to the cut surface. As a result, the plurality of heating portions 41 can be arranged at a constant pitch in the x direction (main scanning direction) across all of the plurality of individual chips 10A.

The electrode layer 3 supported by the substrate 10 is arranged separately from each other on each of the multiple individual chips 10A. The resistor layer 4 supported by the substrate 10 is arranged separately from each other on each of the multiple individual chips 10A. As a result, the formation areas of the electrode layer 3 and resistor layer 4 do not straddle the multiple individual chips 10A. With this configuration, it is possible to prevent poor conductivity in the conductive paths to the multiple heat generating portions 41.

The substrate 10 (multiple individual chips 10A) is bonded to a support member 82 and is supported by a heat dissipation member 81 via the support member 82. By making the support member 82 a plate material with high flatness, it is possible to suppress variation in the position of the multiple individual chips 10A in the z direction (thickness direction), and thus it is possible to suppress variation in the printing quality of the thermal print head B10.

The substrate 10 has a convex portion 12. The convex portion 12 protrudes from the main surface 11 of the substrate 10 and extends in the x direction (main scanning direction). The convex portion 12 is disposed on each of the multiple individual chips 10A, and multiple heat generating portions 41 are disposed on the convex portion 12. With this configuration, the print medium can be accurately brought into contact with the convex portion 12 on which the multiple heat generating portions 41 are disposed, which is expected to improve print quality.

The thermal printhead and the method for manufacturing a thermal printhead according to the second aspect of the present disclosure are not limited to the above-described embodiment. The specific configuration of each part of the thermal printhead and the specific processing of each step of the method for manufacturing a thermal printhead can be freely designed in various ways.

In the above embodiment, the substrate 10 (each individual chip 10A) has a protrusion 12 protruding from the main surface 11, but the substrate 10 may have no protrusion 12. Also, the substrate 10 may have a heat storage layer between the substrate 10 and the heat generating portion 41 (resistor layer 4).

In the above embodiment, the case where the substrate 10 (each individual chip 10A) is supported on the heat dissipation member 81 via the support member 82 has been described, but the substrate 10 (each individual chip 10A) may also be directly supported on the heat dissipation member 81. Figures 55 and 56 show a thermal printhead B20 relating to such a modified example. Unlike the thermal printhead B10, the thermal printhead B20 does not include a support member 82. In the thermal printhead B20, a plurality of individual chips 10A (substrate 10) and a wiring board 5 are directly bonded to the heat dissipation member 81.

The present disclosure is not limited to the embodiments relating to the second aspect described above. The specific configurations of each part of the present disclosure can be freely designed in various ways. The embodiments relating to the second aspect of the present disclosure include the configurations described in Supplementary Notes 1B to 20B below.

Appendix 1B.
A substrate having a main surface facing one side in a thickness direction and made of a Si single crystal semiconductor;
a resistor layer supported by the base material and including a plurality of heat generating portions arranged in a main scanning direction;
an electrode layer supported by the base material and electrically connected to the resistor layer;
the base material is configured to include a plurality of individual chips, each of which has a plurality of heat generating portions arranged thereon and which are aligned in the main scanning direction;
A thermal printhead, wherein a boundary between a pair of individual chips adjacent in the main scanning direction is located between a pair of heat generating portions adjacent in the main scanning direction.
Appendix 2B.
a pair of individual chips adjacent to each other in the main scanning direction, the individual chip located on one side in the main scanning direction has a first side surface facing the other side in the main scanning direction and perpendicular to the main scanning direction;
A thermal printhead as described in Appendix 1B, wherein of a pair of individual chips adjacent to each other in the main scanning direction, the individual chip located on the other side in the main scanning direction faces one side in the main scanning direction and has a second side that is perpendicular to the main scanning direction.
Appendix 3B.
2C. The thermal printhead according to claim 1B, wherein the heat generating portions are arranged at a constant pitch in the main scanning direction across all of the individual chips.
Appendix 4B.
4. The thermal printhead according to claim 1, wherein the electrode layer in each of the individual chips includes a common electrode and a plurality of individual electrodes.
Appendix 5B.
the common electrode has a plurality of common electrode extensions each of which is electrically connected to a pair of heat generating portions adjacent to each other in the main scanning direction and extends in a sub-scanning direction;
The thermal printhead according to claim 4B, wherein the individual electrodes are in contact with the heat generating portions adjacent to the heat generating portions that are electrically connected to the common electrode extension portion, and have individual electrode extension portions extending in the sub-scanning direction.
Appendix 6B.
The thermal printhead according to claim 5B, wherein the common electrode includes a trunk portion that is connected to each of the common electrode extension portions and extends in the main scanning direction.
Appendix 7B.
the resistor layer is disposed on the substrate,
6C. The thermal printhead of claim 1B, wherein the electrode layer is disposed on the resistor layer.
Appendix 8B.
The thermal printhead according to any one of appendices 1B to 7B, wherein the electrode layers are arranged separately from each other on each of the plurality of individual chips.
Appendix 9B.
The thermal printhead according to any one of appendices 1B to 8B, wherein the resistor layers are arranged separately from each other on each of the plurality of individual chips.
Appendix 10B.
1B. The thermal printhead according to claim 1B, further comprising a heat dissipation member supporting the plurality of individual chips.
Appendix 11B.
a support member interposed between the plurality of individual chips and the heat dissipation member,
The thermal printhead of claim 10B, wherein the plurality of individual chips are bonded to the support member.
Appendix 12B.
13. The thermal printhead according to claim 1B, further comprising a drive IC for controlling a current flowing through each of the heat generating portions.
Appendix 13B.
The thermal printhead of claim 12B, further comprising a wire connecting the driving IC and the electrode layer.
Appendix 14B.
13B. The thermal printhead according to claim 12B, further comprising a resin portion covering the driving IC.
Appendix 15B.
The thermal printhead of claim 14B, further comprising a wiring substrate on which the driving IC is disposed.
Appendix 16B.
the base material has a protrusion protruding from the main surface, extending in the main scanning direction, and disposed on each of the plurality of individual chips;
15C. The thermal printhead according to claim 1B, wherein the plurality of heat generating portions are arranged on the convex portion.
Appendix 17B.
The thermal printhead according to claim 16B, wherein the convex portions of the individual chips overlap each other when viewed in the main scanning direction.
Appendix 18B.
A step of preparing a substrate made of a Si single crystal semiconductor;
forming a resistor film on the substrate;
forming an electrode film on the resistor film;
a step of partially removing the electrode film and the resistor film to form an electrode layer and a resistor layer including a plurality of heat generating portions arranged in a main scanning direction;
cutting the base material along a plane perpendicular to the main scanning direction and a plane perpendicular to a sub-scanning direction by irradiating a laser, thereby dividing the base material into a plurality of individual chips;
and arranging the plurality of individual chips on a support so as to be aligned along the main scanning direction,
In the step of dividing the substrate into a plurality of individual chips, the substrate is cut between a pair of heat generating portions adjacent to each other in the main scanning direction.
Appendix 19B.
A method for manufacturing a thermal printhead as described in Appendix 18B, wherein in a process of forming the electrode layer and a resistor layer including a plurality of heat generating portions arranged in a main scanning direction, the resistor layer is formed and arranged separately from one another in areas corresponding to each of the plurality of individual chips, and the electrode layer is arranged separately from one another in areas corresponding to each of the plurality of individual chips.
Appendix 20B.
The method further includes an etching step of anisotropically etching the base material, the etching step being performed before the step of forming the resistor film,
In the etching step, a main surface facing one side in a thickness direction and a convex portion protruding from the main surface are formed in the base material by anisotropic etching;
19B, wherein in the step of forming the plurality of heat generating portions, a plurality of heat generating portions are formed on the convex portion.

[Explanation of symbols according to the second aspect of the embodiment]
B10, B20: Thermal print head 1: Head substrate 10: Substrate 10': Substrate 10A: Individual chip 101: First side 102: Second side 11: Main surface 11': Main surface 12: Convex portion 122: Inclined surface 19: Insulating layer 2: Protective layer 21: Pad opening 3: Electrode layer 3': Electrode film 31: Individual electrode 311: Individual electrode extension 312: Electrode pad portion 32: Common electrode 321: Common electrode extension 322: Branch portion 323: Main portion 33: Relay electrode 331: Relay electrode extension 332: Connection portion 4: Resistor layer 4': Resistor film 41: Heat generating portion 5: Wiring substrate 51: Individual wiring portion 52: Common wiring portion 59: Connector 61, 62, 63: Wire 7: Driver IC
71: Pad portion 78: Resin portion 81: Heat dissipation member 82: Support member 91: Assembly board 99: Platen roller

Next, an embodiment relating to the third aspect of the present disclosure will be described with reference to Figures 57 to 88.

Patent Document 2 discloses an example of a conventional thermal printhead. In this conventional thermal printhead, a convex portion is formed on the main surface of the substrate, extending in the main scanning direction and protruding from the main surface. As shown in Figure 6 of Patent Document 2, a plurality of heat generating portions are arranged in the main scanning direction on the convex portion. With this configuration, the print medium can be brought into accurate contact with the heat generating portions, which is expected to improve print quality.

The thermal printhead disclosed in Patent Document 2 can be used, for example, for barcode printing and two-dimensional code printing. To achieve this, the thermal printhead needs to be made even smaller, and there is still room for improvement. Thus, one of the objectives of the third aspect of the present disclosure is to provide a thermal printhead that can be made smaller.

Based on Figures 57 to 68, a thermal printhead C10 according to the first embodiment of the third aspect will be described. The thermal printhead C10 forms a main part of the thermal printer 100 (Figure 60). The thermal printhead C10 mainly comprises a base material 1, an insulating layer 21, a resistor layer 3, a wiring layer 4, and a protective layer 5. In addition to these, the thermal printhead C10 comprises a first substrate 61, a second substrate 62, a first interconnection wiring 63, a plurality of second interconnection wirings 64, a plurality of driving elements 65, and a heat dissipation member 66. In Figures 57 to 59, the protective layer 5 is shown through for ease of understanding. In Figure 63, the insulating layer 21, the resistor layer 3, the wiring layer 4, the first substrate 61, the second substrate 62, and the second interconnection wiring 64 are further shown through for ease of understanding (see Figure 57). In Fig. 63, the first substrate 61 and the second substrate 62 are respectively indicated by imaginary lines (two-dot chain lines). For ease of understanding, in Fig. 65, Fig. 67, and Fig. 68, only the base material 1 and the first interconnection wiring 63 are illustrated.

In the thermal printhead C10, as shown in FIG. 60, the substrate 1 is joined to a heat dissipation member 66. The substrate 1 supports a first substrate 61 and a second substrate 62. A plurality of heat generating portions 31 (described later) that form part of the resistor layer 3 and are arranged in the x-direction are formed on the substrate 1. The plurality of heat generating portions 31 are selectively heated by a plurality of drive elements 65 mounted on the second substrate 62. The plurality of drive elements 65 are driven in accordance with a print signal transmitted from the outside via a connector (not shown) mounted on the first substrate 61.

As shown in FIG. 60, the thermal printer 100 includes a thermal printhead C10 and a platen roller 69. In the thermal printer 100, the platen roller 69 is configured to feed a recording medium 68 such as thermal paper. With the platen roller 69 pressing the recording medium 68 against a plurality of heat generating parts 31, the plurality of heat generating parts 31 print on the recording medium 68. In the thermal printer 100, other mechanisms (non-roller-shaped mechanisms) can be used in place of the platen roller 69. For example, such mechanisms include those having a flat pressing surface. The term "flat surface" includes curved surfaces having a sufficiently small curvature. In this disclosure, the roller-shaped mechanism and other mechanisms are collectively referred to as "platen."

As shown in Fig. 57, the substrate 1 is in the form of a strip extending along the x-direction. The substrate 1 is made of a semiconductor material. The semiconductor material is, for example, a single crystal material of silicon (Si), but the present disclosure is not limited thereto.

As shown in Figure 61, the substrate 1 has a principal surface 11 and a rear surface 15. The principal surface 11 and the rear surface 15 are spaced apart from each other in the z direction. The principal surface 11 and the rear surface 15 face opposite each other in the z direction. The principal surface 11 and the rear surface 15 of the substrate 1 both have Miller indices of (100). As shown in Figure 60, in the thermal printhead C10, the principal surface 11 faces the platen roller 69, and the rear surface 15 faces the heat dissipation member 66.

As shown in Figure 61, the substrate 1 has a protrusion 12. The protrusion 12 protrudes from the main surface 11 in the z direction. As shown in Figure 57, the protrusion 12 extends long along the x direction.

As shown in FIG. 62, the convex portion 12 has a top surface 121 and a pair of inclined surfaces 122. The top surface 121 is located away from the main surface 11 in the z direction and is parallel to the main surface 11. The pair of inclined surfaces 122 are located away from each other in the y direction. The pair of inclined surfaces 122 are connected to the top surface 121 and the main surface 11. The pair of inclined surfaces 122 are inclined with respect to the main surface 11 so as to approach each other from the main surface 11 to the top surface 121. The inclination angles α of the pair of inclined surfaces 122 with respect to the main surface 11 are equal to each other.

As shown in Figures 57, 63 and 64, the substrate 1 has a pair of end faces 13 and a first surface 14. The pair of end faces 13 face opposite each other in the x direction and are connected to the rear surface 15. The first surface 14 is located between at least one of the pair of end faces 13 and the convex portion 12 in the x direction. In the thermal printhead C10, the first surface 14 includes a pair of separation regions 14A located on both sides of the convex portion 12. The surface roughness of the first surface 14 is greater than the surface roughness of the main surface 11.

As shown in Figure 64, the first surface 14 is located closer to the main surface 11 in the z direction than the top surface 121 of the convex portion 12. Therefore, as shown in Figure 65, the distance h1 in the z direction from the main surface 11 to the first surface 14 is smaller than the distance h2 in the z direction from the first surface 14 to the top surface 121. The first surface 14 is located between the main surface 11 and the top surface 121 in the z direction. Therefore, the first surface 14 protrudes from the main surface 11 in the z direction by a distance h1. The width b (dimension in the y direction) of the first surface 14 is smaller than the width B of the bottom of the convex portion 12 (dimension in the y direction of the bottom of the convex portion 12).

67 and 68 show thermal printheads C11 and C12, which are modified versions of thermal printhead C10. In each of thermal printheads C11 and C12, the configuration of the first surface 14 is different from the configuration of thermal printhead C10 (see FIG. 65).

As shown in Figure 67, in thermal printhead C11, the first surface 14 is flush with the main surface 11. The width b of the first surface 14 is the same as the width B of the bottom of the convex portion 12.

As shown in Figure 68, in thermal printhead C12, the first surface 14 is located between the main surface 11 and the back surface 15 in the z direction. Therefore, the first surface 14 is recessed from the main surface 11 in the z direction and reaches both ends of the substrate 1 in the y direction. The width b of the first surface 14 is greater than the width B of the bottom of the convex portion 12 and is equal to the dimension of the substrate 1 in the y direction.

The configurations of the first surface 14 in thermal printhead C10, thermal printhead C11, and thermal printhead C12 are due to differences in the removal depth (dimension in the z direction) of the convex portions 12. In the manufacturing method of thermal printhead C10 described below, the first surface 14 is formed by removing at least a portion of both ends of the convex portions 12 in the y direction (see Figures 71 to 73). Thermal printhead C10 is the case where the removal depth of the convex portions 12 is the shallowest. On the other hand, thermal printhead C12 is the case where the removal depth of the convex portions 12 is the deepest.

63 and 66, a plurality of linear scratches 141 each extending along the y direction are formed on the first surface 14. In the thermal printhead C10, at least one of the plurality of linear scratches 141 includes a portion that protrudes from the main surface 11 (see FIG. 66) in the z direction.

As shown in Fig. 62, the insulating layer 21 covers the main surface 11 and the protrusions 12 of the substrate 1. The insulating layer 21 electrically insulates the substrate 1 from the resistor layer 3 and the wiring layer 4. The insulating layer 21 is made of silicon dioxide ( _SiO2 ) using tetraethyl orthosilicate (TEOS) as a raw material, for example. An example of the thickness of the insulating layer 21 is 1 µm or more and 15 µm or less. As shown in Fig. 64, the insulating layer 21 also covers the first surface 14 of the substrate 1.

As shown in Figures 61 and 62, the resistor layer 3 is formed on the main surface 11 and the protrusions 12 of the substrate 1. The resistor layer 3 is in contact with the insulating layer 21. As a result, in the thermal printhead C10, the insulating layer 21 is sandwiched between the substrate 1 and the resistor layer 3. The resistor layer 3 is made of, for example, tantalum nitride (TaN). An example of the thickness of the resistor layer 3 is 0.02 μm or more and 0.1 μm or less.

58, 59 and 62, the resistor layer 3 includes a plurality of heat generating portions 31. In the resistor layer 3, the plurality of heat generating portions 31 are exposed from the wiring layer 4. The plurality of heat generating portions 31 are selectively energized from the wiring layer 4, so that the plurality of heat generating portions 31 locally heat the recording medium 68. The plurality of heat generating portions 31 are arranged in parallel along the x direction. Among the plurality of heat generating portions 31, two adjacent heat generating portions 31 in the x direction are located apart from each other. In the thermal print head C10, the plurality of heat generating portions 31 are formed above the top surface 121 of the convex portion 12 of the substrate 1. Therefore, when viewed along the z direction, the plurality of heat generating portions 31 overlap the top surface 121. As shown in FIG. 60, in the thermal printer 100, the plurality of heat generating portions 31 face the platen roller 69.

As shown in Figures 61 and 62, the wiring layer 4 is formed in contact with the resistor layer 3. In the thermal print head C10, the wiring layer 4 is formed on the resistor layer 3. The wiring layer 4 forms a conductive path for passing electricity through the multiple heating parts 31 of the resistor layer 3. The electrical resistivity of the wiring layer 4 is smaller than that of the resistor layer 3. The wiring layer 4 is a metal layer made of, for example, copper (Cu). An example of the thickness of the wiring layer 4 is 0.3 μm or more and 2.0 μm or less. In addition, the wiring layer 4 may be configured to be made of two metal layers, a titanium (Ti) layer laminated on the resistor layer 3 and a copper layer laminated on the titanium layer. In this case, an example of the thickness of the titanium layer is 0.1 μm or more and 0.2 μm or less.

As shown in Figure 58, the wiring layer 4 includes a common wiring 41 and multiple individual wirings 42. The common wiring 41 is located on one side in the y direction (downstream side) of the multiple heat generating portions 31 of the resistor layer 3. The multiple individual wirings 42 are located on the other side in the y direction (upstream side) of the multiple heat generating portions 31. As shown in Figure 59, when viewed along the z direction, multiple areas of the resistor layer 3 sandwiched between the common wiring 41 and the multiple individual wirings 42 are the multiple heat generating portions 31.

58 and 59, the common wiring 41 has a base 411 and a plurality of extensions 412. In the y direction, the base 411 is located along the downstream periphery of the main surface 11 of the substrate 1. The base 411 is a strip extending along the x direction. Each of the plurality of extensions 412 is a strip extending from an end of the base 411 facing the convex portion 12 of the substrate 1 in the y direction toward the plurality of heat generating portions 31. The plurality of extensions 412 are arranged side by side along the x direction. A portion of each of the plurality of extensions 412 is formed on the inclined surface 122 located on one side (downstream side) of the pair of inclined surfaces 122 of the substrate 1 in the y direction. Therefore, a portion of the common wiring 41 is formed on the inclined surface 122 located on one side of the pair of inclined surfaces 122 in the y direction. In the common wiring 41 , a current flows from a base portion 411 through a plurality of extension portions 412 to a plurality of heat generating portions 31 .

58 and 59, each of the multiple individual wirings 42 is a strip extending from the upstream periphery of the main surface 11 of the substrate 1 toward the multiple heat generating parts 31. The multiple individual wirings 42 are arranged side by side along the x direction. A part of each of the multiple individual wirings 42 is formed on the inclined surface 122 located on the other side (upstream side) in the y direction of the pair of inclined surfaces 122 of the substrate 1. In each of the multiple individual wirings 42, a current flows from one of the multiple heat generating parts 31 toward the upstream side. When viewed along the z direction, each of the multiple heat generating parts 31 is sandwiched between one of the multiple individual wirings 42 and one of the multiple extension parts 412 of the common wiring 41. The configurations of the wiring layer 4 and the multiple heat generating parts 31 shown in FIGS. 58 and 59 are examples. The configurations of the wiring layer 4 and the multiple heat generating parts 31 in the present disclosure are not limited to the configurations shown in FIGS. 58 and 59.

As shown in FIG. 61, the protective layer 5 covers the plurality of heat generating parts 31 of the resistor layer 3 and the wiring layer 4. The protective layer 5 has electrical insulation properties. The protective layer 5 contains silicon. The protective layer 5 is made of, for example, silicon dioxide, silicon nitride (Si ₃ N ₄ ), or silicon carbide (SiC). Alternatively, the protective layer 5 may be a laminate made of a plurality of types of these materials. An example of the thickness of the protective layer 5 is 1.0 μm or more and 10 μm or less. In the thermal printer 100, the recording medium 68 is pressed against the area of the protective layer 5 that covers the plurality of heat generating parts 31 by the platen roller 69 shown in FIG. 60. As shown in FIG. 64, the protective layer 5 also covers the area of the insulating layer 21 that covers the first surface 14 of the substrate 1.

61, the protective layer 5 has a first opening 51 and a second opening 52. Each of the first opening 51 and the second opening 52 is a strip extending along the x direction. Each of the first opening 51 and the second opening 52 penetrates the protective layer 5 in the z direction. The first opening 51 is located on the downstream side. The first opening 51 is formed up to the most downstream side of the substrate 1 (referring to the left end of the substrate 1 in FIG. 61). In addition, a configuration may be used in which a region of the protective layer 5 is formed that is located on the most downstream side of the substrate 1 relative to the first opening 51 and extends in a strip shape along the x direction. The base 411 of the common wiring 41 is exposed from the first opening 51. The second opening 52 is located on the upstream side. The second opening 52 is formed up to the most upstream side of the substrate 1 (referring to the right end of the substrate 1 in FIG. 61). Alternatively, a region of the protective layer 5 may be formed that is located on the most upstream side of the substrate 1 with respect to the second opening 52 and extends in a band shape along the x direction. A portion of each of the plurality of individual wirings 42 is exposed from the second opening 52.

As shown in FIG. 60, the first substrate 61 is supported by the downstream side of the substrate 1 and the heat dissipation member 66. As shown in FIG. 60, the second substrate 62 is supported by the upstream side of the substrate 1 and the first substrate 61. Each of the first substrate 61 and the second substrate 62 is, for example, an FPC (Flexible Printed Circuits) and has flexibility. As shown in FIG. 1, when viewed along the z direction, each of the first substrate 61 and the second substrate 62 is rectangular with the x direction as the long side direction. When viewed along the z direction, the area of the first substrate 61 is larger than the area of the second substrate 62. The first substrate 61 and the second substrate 62 may be a single substrate integrated with each other, instead of two substrates as in the thermal printhead C10.

1 and 60, the first substrate 61 has an inner surface 611, an outer surface 612, and an opening 613. The inner surface 611 and the outer surface 612 face opposite each other in the z direction. The inner surface 611 faces the heat dissipation member 66. The outer surface 612 faces the platen roller 69. The opening 613 penetrates the first substrate 61 in the z direction. The opening 613 is located on the upstream side of the base material 1. The opening 613 is a space in which a plurality of driving elements 65 are housed. As shown in FIG. 60, the second substrate 62 is supported on the outer surface 612 of the first substrate 61. The second substrate 62 has a mounting surface 621. The mounting surface 621 faces the same side as the inner surface 611 in the z direction. A portion of the mounting surface 621 is exposed from the opening 613.

As shown in FIG. 61, the first connection wiring 63 is disposed on the inner surface 611 of the first substrate 61. As shown in FIG. 1, the first connection wiring 63 has a first wiring portion 631 and a pair of second wiring portions 632. The first wiring portion 631 extends along the x direction. The upstream end of the first wiring portion 631 is connected to the base portion 411 of the common wiring 41 formed on the main surface 11 of the substrate 1. This connection is made by using a conductive bonding material such as solder. As a result, the first connection wiring 63 is conductive to the common wiring 41. The pair of second wiring portions 632 are connected to both ends of the first wiring portion 631 in the x direction. Each of the pair of second wiring portions 632 extends from the first wiring portion 631 toward the upstream side. As shown in FIG. 63 and FIG. 65, the pair of second wiring portions 632 individually straddle a pair of separation regions 14A of the first surface 14 of the substrate 1. 64 , the pair of second wiring parts 632 face the protective layer 5. The pair of second wiring parts 632 are connected to a connector mounted on the first substrate 61. As a result, power is supplied to the common wiring 41 from the connector.

As shown in Figure 60, the region of the first substrate 61 located upstream of the convex portion 12 is located closer to the rear surface 15 of the base material 1 in the z direction than the region of the first substrate 61 located downstream of the convex portion 12. A pair of second wiring parts 632 (see Figure 57) arranged on the first substrate 61 are flexible together with the first substrate 61. This allows the position in the z direction of each of the pair of second wiring parts 632 to change from the downstream side to the upstream side so as to get closer to the rear surface 15 in the portion that straddles one of the pair of separation regions 14A of the first surface 14 in the y direction.

As shown in FIG. 61, the second interconnection wirings 64 are arranged on the mounting surface 621 of the first substrate 61. As shown in FIG. 58, each of the second interconnection wirings 64 has a pad portion 641 and an extension portion 642. The pad portions 641 of the second interconnection wirings 64 are arranged in a staggered arrangement in the x direction. In detail, the pad portions 641 of the second interconnection wirings 64 include two rows of pad portions 641 arranged in the x direction. In each of the two rows of pad portions 641, the pad portions 641 are arranged side by side along the x direction at an equal pitch p (the pitch p is the center-to-center distance between two adjacent pad portions 641 in the x direction). Of the two rows of pad portions 641, the row of pad portions 641 located on the upstream side and the row of pad portions 641 located on the downstream side are arranged with a shift in the x direction by a distance of 1/2 the pitch p. The extension portion 642 is a strip-like shape extending downstream from either end of the pad portion 641 of the second communication wirings 64 facing the protrusion 12 of the base material 1 in the y direction. The downstream ends of the extension portions 642 of the second communication wirings 64 are individually connected to the individual wirings 42. This connection is made by using a conductive bonding material such as solder. As a result, the second communication wirings 64 are individually conductive to the individual wirings 42.

As shown in FIG. 1 and FIG. 60, the multiple driving elements 65 are mounted on the mounting surface 621 of the second substrate 62. Each of the multiple driving elements 65 is a semiconductor element in which various circuits are configured. Each of the multiple driving elements 65 is mounted by COF (Clip On Film) on some of the pad parts 641 of the multiple second connecting wirings 64 and some of the multiple wirings (not shown) arranged on the mounting surface 621 and different from the multiple second connecting wirings 64. The multiple wirings are connected to a connector. As a result, print signals, control signals, and power for operating the multiple driving elements 65 are input from the connector to the multiple driving elements 65 through the multiple wirings. Based on these electrical signals, the multiple driving elements 65 switch the connection between the multiple individual wirings 42 connected through the multiple second connecting wirings 64 and the ground electrode (not shown) to ON or OFF. In addition, power is supplied from the connector to the multiple heating parts 31 of the resistor layer 3 through the first connecting wirings 63 arranged on the first substrate 61. As a result, among the plurality of heat generating portions 31, the heat generating portion 31 in which the connection between any one of the plurality of individual wirings 42 and the ground electrode is turned on selectively generates heat.

As shown in FIG. 60, the heat dissipation member 66 faces the rear surface 15 of the base material 1 and the inner surface 611 of the first substrate 61. The rear surface 15 is joined to the heat dissipation member 66. The first substrate 61 is supported by the heat dissipation member 66. The first substrate 61 is fixed to the heat dissipation member 66 by fastening members such as screws. When the thermal printhead C10 is in use, a portion of the heat generated from the multiple heat generating portions 31 of the resistor layer 3 is conducted to the heat dissipation member 66 via the base material 1. The heat conducted to the heat dissipation member 66 is dissipated to the outside. The heat dissipation member 66 is made of, for example, aluminum (Al).

Based on Figures 69 to 80, an example of a manufacturing method for thermal printhead C10 is described.

As shown in Figures 69 and 70, a main surface 11 and a convex portion 12 are formed on a substrate 81. Specifically, as shown in Figure 69, a first mask layer 891 that covers a part of the substrate 81 and a second mask layer 892 that covers the first mask layer 891 are formed. The substrate 81 is made of a semiconductor material. The semiconductor material is, for example, a single crystal material of silicon. The substrate 81 is a silicon wafer. In a direction perpendicular to the z direction, a plurality of regions corresponding to each of the plurality of substrates 1 are connected together to form the substrate 81. The substrate 81 has a first surface 81A and a second surface 81B. The first surface 81A and the second surface 81B face opposite each other in the z direction. The first surface 81A and the second surface 81B of the substrate 81 are both surfaces with Miller indices (100).

The first mask layer 891 is formed to cover the first surface 81A and the second surface 81B. The first mask layer 891 is made of silicon dioxide. The second mask layer 892 is formed to cover the area of the first mask layer 891 that covers the first surface 81A. The second mask layer 892 is made of silicon nitride. The first mask layer 891 and the second mask layer 892 are formed by a first process described later. As shown in FIG. 69, the first mask layer 891 that covers a part of the first surface 81A and the second mask layer 892 that covers the first mask layer 891 are formed by a second process described later. The first mask layer 891 and the second mask layer 892 that covers the first mask layer 891 have mask openings 893 that penetrate in the z direction.

When forming the first mask layer 891 and the second mask layer 892, first, a thin film of silicon dioxide is formed by thermal oxidation to cover the first surface 81A and the second surface 81B. Then, a thin film of silicon nitride is formed by thermal CVD (Chemical Vapor Deposition) to cover the area of the first mask layer 891 that covers the first surface 81A. This is the first process. Next, as the second process, a part of the area of the thin film of silicon dioxide covering the first surface 81A and a part of the thin film of silicon nitride covering the area are removed by lithography patterning and reactive ion etching (RIE). As a result, as shown in FIG. 69, the first mask layer 891 and the second mask layer 892 are formed, and mask openings 893 are formed in the first mask layer 891 that covers a part of the first surface 81A and the second mask layer 892 that covers the first mask layer 891.

As an alternative method for the first step, a method may be used in which a thin film of silicon nitride covering the first surface 81A and the second surface 81B is formed by thermal CVD. In this case, in the second step, a predetermined area on the first surface 81A covered by the first mask layer 891 and a mask opening 893, which is an area other than the first surface 81A where the first surface 81A is exposed, are formed by lithographic patterning and reactive ion etching.

70, the main surface 11 and the convex portion 12 are formed on the substrate 81. The main surface 11 and the convex portion 12 are formed by wet etching the area of the first surface 81A exposed by the mask opening 893 shown in FIG. 69 using an aqueous solution of potassium hydroxide (KOH). This etching is anisotropic. Finally, the first mask layer 891 and the second mask layer 892 are removed by wet etching using hydrofluoric acid (HF). As a result, the main surface 11 and the convex portion 12 are formed on the substrate 81. Furthermore, the second surface 81B of the substrate 81 becomes the back surface 15. The area of the first surface 81A covered by the first mask layer 891 and the second mask layer 892 becomes the top surface 121 of the convex portion 12. The inclination angle α of each of the pair of inclined surfaces 122 of the convex portion 12 with respect to the main surface 11 is equal to each other. This is due to the fact that the convex portion 12 is formed by anisotropic etching.

Next, as shown in Figs. 71 to 73, at least one of the ends of the convex portion 12 of the substrate 81 in the x direction is removed. In the illustrated example, both ends of the convex portion 12 are removed. As shown in Fig. 71, in this process, a dicing blade 88 rotating around the x direction is pressed against the convex portion 12, thereby removing both ends of the convex portion 12. As shown in Fig. 72, the dicing blade 88 is pressed against the convex portion 12 while shifting its position in the x direction in sequence according to the x-direction dimension of the convex portion 12 to be removed. In addition, when removing the ends of the convex portion 12, a method can be adopted in which the dicing blade 88 provides a plurality of cuts in the convex portion 12 that are spaced apart from each other in the x direction, and then the convex portion 12 divided by the plurality of cuts is removed by wet etching. Through this process, a first surface 14 is formed on the substrate 81 as shown in Fig. 73. A plurality of linear scratches 141 each extending along the y direction are formed on the first surface 14. In the substrate 1 , the surface roughness of the first surface 14 is greater than the surface roughness of the main surface 11 .

In the example shown in Figures 71 and 72, the thickness (dimension in the x direction) of the dicing blade 88 is constant along the z direction. Alternatively, a dicing blade whose thickness gradually decreases as it approaches the periphery (i.e., as it approaches the main surface 11 of the substrate 81 in the z direction) may be used. In this case, the shape of the removed portion of the convex portion 12 (as viewed along the y direction; see Figure 71) becomes trapezoidal (the lower base is shorter than the upper base). As a result, the end face facing the x direction of the convex portion 12 shown in Figure 64 (the end face facing the right in Figure 64) is inclined downward to the right from the top surface 121 toward the main surface 11.

Next, as shown in Fig. 74, an insulating layer 21 is formed to cover the main surface 11 and the protrusions 12 of the substrate 81. The insulating layer 21 is made by laminating multiple thin films of silicon dioxide. Each thin film can be formed by plasma CVD using, for example, tetraethyl orthosilicate (TEOS) as a raw material gas.

Next, as shown in Figures 75 to 77, the resistor layer 3 and the wiring layer 4 are formed. The resistor layer 3 includes a plurality of heat generating portions 31 arranged in the x direction. The wiring layer 4 is electrically connected to the plurality of heat generating portions 31. The process of forming the wiring layer 4 includes a process of forming a common wiring 41 and a plurality of individual wirings 42. In the substrate 81, the common wiring 41 is located on one side in the y direction relative to the plurality of heat generating portions 31 of the resistor layer 3 shown in Figure 77. In the substrate 81, the plurality of individual wirings 42 are located on the other side in the y direction relative to the plurality of heat generating portions 31 shown in Figure 77.

Specifically, as shown in Fig. 75, a resistor film 82 is formed on the main surface 11 and the protrusions 12 of the substrate 81. The resistor film 82 is formed so as to cover the entire surface of the insulating layer 21. The resistor film 82 is formed by laminating a thin film of tantalum nitride on the insulating layer 21 by a sputtering method.

76, a conductive layer 83 is formed to cover the entire surface of the resistor film 82. The conductive layer 83 is formed by laminating a thin copper film multiple times on the resistor film 82 by a sputtering method. Alternatively, the conductive layer 83 may be formed by laminating a thin titanium film on the resistor film 82 by a sputtering method, and then laminating a thin copper film multiple times on the thin titanium film by a sputtering method.

Next, as shown in FIG. 77, the conductive layer 83 is lithographically patterned, and then a portion of the conductive layer 83 is removed. The removal is performed by wet etching using a mixed solution of sulfuric acid (H ₂ SO ₄ ) and hydrogen peroxide (H ₂ O ₂ ). As a result, the common wiring 41 and a plurality of individual wirings 42 are formed in contact with the resistor film 82. This completes the formation of the wiring layer 4. Furthermore, the region of the resistor film 82 formed on the top surface 121 of the convex portion 12 of the substrate 81 is exposed from the wiring layer 4. Next, the portion of the resistor film 82 that is no longer necessary in the thermal print head C10 is removed. The removal is performed by reactive ion etching. As a result, the resistor layer 3 is formed on the main surface 11 and the convex portion 12 of the substrate 81. A plurality of heating portions 31 are formed on the top surface 121 of the substrate 81.

Next, as shown in Figure 78, a protective layer 5 is formed to cover the multiple heating portions 31 of the resistor layer 3 and the wiring layer 4. The protective layer 5 is formed by laminating a thin film of silicon nitride by plasma CVD.

Next, as shown in FIG. 79, a first opening 51 and a second opening 52 penetrating in the z-direction are formed in the protective layer 5. The first opening 51 and the second opening 52 are formed by removing a portion of the protective layer 5 after lithographic patterning of the protective layer 5. The removal is performed by reactive ion etching. As a result, the base 411 of the common wiring 41 is exposed from the first opening 51. A portion of each of the multiple individual wirings 42 is exposed from the second opening 52.

Next, the substrate 81 is divided into individual pieces by cutting the substrate 81 along the x-direction and the y-direction. This results in the substrate 1 of the thermal printhead C10. A pair of end faces 13 is formed on the substrate 1. Next, as shown in FIG. 80, the second substrate 62 on which the multiple second interconnection wirings 64 are arranged is supported on the first substrate 61 on which the first interconnection wirings 63 are arranged, and then the first wiring portion 631 of the first interconnection wiring 63 is connected to the base portion 411 of the common wiring 41. In addition, the multiple second interconnection wirings 64 are individually connected to the multiple individual wirings 42. These two types of connections are made by using a conductive bonding material such as solder. This results in a configuration in which the first substrate 61 and the second substrate 62 are supported by the substrate 1. Next, multiple drive elements 65 are mounted on the mounting surface 621 of the second substrate 62. Finally, the back surface 15 of the substrate 1 and the first substrate 61 are joined to the heat dissipation member 66. Through the above steps, the thermal printhead C10 is obtained.

Next, the effect of the thermal print head C10 will be explained.

The substrate 1 of the thermal printhead C10 has a main surface 11, a convex portion 12, a pair of end faces 13, and a first surface 14. The first surface 14 is located between at least one of the pair of end faces 13 and the convex portion 12 in the x direction, and is located closer to the main surface 11 than the top surface 121 of the convex portion 12 in the z direction. The thermal printhead C10 has a connection wiring (first connection wiring 63) that is conductive to the wiring layer 4 and spans the first surface 14. By adopting this configuration, even if the size of the substrate 1 is reduced, a conductive path for the wiring layer 4 (common wiring 41) can be provided on the substrate 1. In this way, the thermal printhead C10 contributes to miniaturization.

The first surface 14 of the substrate 1 includes two spaced apart regions 14A, each located at either end of the protrusion 12. The interconnection wiring straddles the spaced apart region 14A. This allows the thermal printhead C10 to be miniaturized while still increasing the cross-sectional area of the conduction path for the common wiring 41, making it possible to supply greater power to the common wiring 41.

The thermal printhead C10 further includes a substrate (first substrate 61) on which interconnection wiring is arranged. The interconnection wiring is electrically connected to the common wiring 41. This eliminates the need for a process for forming interconnection wiring on the base material 1 in the manufacture of the thermal printhead C10. Furthermore, because the interconnection wiring is integrated with the substrate, it is possible to prevent the pattern of the interconnection wiring from being broken due to factors such as external force.

In the thermal printhead C10, a portion of the common wiring 41 and a portion of each of the multiple individual wirings 42 are formed on one of a pair of inclined surfaces 122 of the protrusion 12. This makes it possible to further reduce the y-direction dimension of each of the multiple heat generating parts 31 when viewed along the z-direction, while further reducing the contact area of the recording medium 68 with the thermal printhead C10. Therefore, it is possible to further improve the quality of printing on the recording medium 68 while suppressing the amount of heat generated in the thermal printhead C10.

In the substrate 1, the pair of inclined surfaces 122 are inclined with respect to the main surface 11 so as to approach each other from the main surface 11 to the top surface 121. Such a shape of the convex portion 12 is obtained by forming the convex portion 12 on the substrate 81 by anisotropic etching in the manufacturing process of the thermal printhead C10 shown in Figure 66. This is because the substrate 81 is made of a semiconductor material and the semiconductor material contains a single crystal silicon material.

The thermal printhead C10 includes a protective layer 5 that covers a plurality of heat generating portions 31 and the wiring layer 4. This allows the plurality of heat generating portions 31 and the wiring layer 4 to be protected by the protective layer 5, and also reduces the frictional force of the recording medium 68 against the thermal printhead C10.

The thermal printhead C10 further includes a heat dissipation member 66. The rear surface 15 of the substrate 1 is joined to the heat dissipation member 66. This allows a portion of the heat generated from the multiple heat generating parts 31 during use of the thermal printhead C10 to be quickly dissipated to the outside via the substrate 1 and the heat dissipation member 66.

A thermal printhead C20 according to a second embodiment of the third aspect will be described with reference to Fig. 81. In Fig. 81, elements that are the same as or similar to the thermal printhead C10 described above are given the same reference numerals, and duplicated explanations will be omitted. In Fig. 81, the protective layer 5 is shown through for ease of understanding.

In thermal printhead C20, the configuration of the first surface 14 of the substrate 1 and the configuration of the first connecting wiring 63 differ from those of thermal printhead C10.

As shown in Figure 81, the first surface 14 of the substrate 1 is located between one of the pair of end faces 13 and the convex portion 12 in the x direction. For this reason, in the thermal printhead C20, the first surface 14 does not include a pair of separation regions 14A. As a result, the first connecting wiring 63 has a first wiring portion 631 and a second wiring portion 632. The second wiring portion 632 is connected to only one of the ends of the first wiring portion 631 in the x direction where the first surface 14 is located.

Next, the effect of thermal print head C20 will be explained.

The substrate 1 of the thermal printhead C20 has a main surface 11, a convex portion 12, a pair of end faces 13, and a first surface 14. The first surface 14 is located between at least one of the pair of end faces 13 and the convex portion 12 in the x direction, and is located closer to the main surface 11 than the top surface 121 of the convex portion 12 in the z direction. The thermal printhead C20 has a connection wiring (first connection wiring 63) that is conductive to the wiring layer 4 and spans the first surface 14. Therefore, the thermal printhead C20 also makes it possible to miniaturize the thermal printhead. Furthermore, the thermal printhead C20 has a configuration in common with the thermal printhead C10, and thereby achieves the same effects as the thermal printhead C10.

A thermal printhead C30 according to a third embodiment of the third aspect will be described with reference to Figures 82 and 83. In these figures, elements that are the same as or similar to those of the thermal printhead C10 described above are given the same reference numerals, and duplicated descriptions will be omitted. In Figure 82, for ease of understanding, the protective layer 5 is shown through. In Figure 83, for ease of understanding, the insulating layer 21, resistor layer 3, wiring layer 4 (excluding the base 411 of the common wiring 41), and multiple second connecting wirings 64 are also shown through.

The thermal printhead C30 differs from the thermal printhead C10 in the configuration of the first interconnection wiring 63 and in that it further includes a third interconnection wiring 67. Furthermore, the thermal printhead C30 does not include a first substrate 61.

82 and 83, the first interconnection wiring 63 includes two regions located apart from each other in the x direction. These two regions are respectively connected to both ends in the x direction of the base 411 of the common wiring 41. This allows the first interconnection wiring 63 to be conductive to the common wiring 41. The first interconnection wiring 63 is formed on the main surface 11 of the substrate 1 together with the wiring layer 4. Therefore, the first interconnection wiring 63 is made of the same metal layer as the metal layer constituting the wiring layer 4. The first interconnection wiring 63 extends from the base 411 toward the upstream side and straddles a pair of spaced apart regions 14A on the first surface 14 of the substrate 1.

As shown in Figures 82 and 83, the third connecting wiring 67 includes two regions located apart from each other in the x direction. The third connecting wiring 67 is disposed on the mounting surface 621 of the second substrate 62. Each of the two regions of the third connecting wiring 67 extends along the y direction. The downstream end of the third connecting wiring 67 is connected to the first connecting wiring 63. As a result, the third connecting wiring 67 is conductive to the common wiring 41 via the first connecting wiring 63. The third connecting wiring 67 is connected to a connector. Power is supplied to the common wiring 41 via the connector.

Next, the effect of thermal print head C30 will be explained.

The substrate 1 of the thermal printhead C30 has a main surface 11, a convex portion 12, a pair of end faces 13, and a first surface 14. The first surface 14 is located between at least one of the pair of end faces 13 and the convex portion 12 in the x direction, and is located closer to the main surface 11 than the top surface 121 of the convex portion 12 in the z direction. The thermal printhead C30 is provided with a connection wiring (first connection wiring 63) that is conductive to the wiring layer 4 and spans the first surface 14. Therefore, the thermal printhead C30 also makes it possible to achieve miniaturization. Furthermore, the thermal printhead C30 has a configuration in common with the thermal printhead C10, and thereby achieves the same effects as the thermal printhead C10.

In the thermal printhead C30, the interconnect wiring is formed on the main surface 11 of the substrate 1 together with the wiring layer 4. This eliminates the need for a substrate (first substrate 61) for arranging the interconnect wiring. This makes it possible to further reduce the y-direction dimension of the thermal printhead C30.

A thermal printhead C40 according to a fourth embodiment of the third aspect will be described with reference to Figures 84 and 85. In these figures, elements that are the same as or similar to the thermal printhead C10 described above are given the same reference numerals, and duplicate descriptions will be omitted.

In thermal printhead C40, the configuration of the convex portion 12 of the substrate 1 and the configuration of the multiple heating portions 31 of the resistor layer 3 differ from those of thermal printhead C10.

84 and 85, each of the pair of inclined surfaces 122 of the convex portion 12 includes a first inclined surface 122A and a second inclined surface 122B. The first inclined surface 122A is connected to the main surface 11 of the substrate 1. The second inclined surface 122B is connected to the top surface 121 of the convex portion 12 and the first inclined surface 122A. In each of the pair of inclined surfaces 122, the inclination angle α2 of the second inclined surface 122B with respect to the main surface 11 is smaller than the inclination angle α1 of the first inclined surface 122A with respect to the main surface 11. Such a pair of inclined surfaces 122 is formed by performing wet etching using a tetramethylammonium hydroxide (TMAH) aqueous solution on the boundary 123 between the top surface 121 and the pair of inclined surfaces 122 and their vicinity between the process shown in FIG. 70 and the process shown in FIG. 74 in the manufacture of the thermal printhead C10.

As shown in FIG. 85, the multiple heat generating parts 31 of the resistor layer 3 are formed in the following manner. First, the multiple heat generating parts 31 are formed on the top surface 121 of the convex portion 12. Second, the multiple heat generating parts 31 are formed across the top surface 121 and the second inclined surface 122B of the inclined surface 122 located downstream of the pair of inclined surfaces 122 of the convex portion 12. Third, the multiple heat generating parts 31 are formed across the top surface 121 and the second inclined surface 122B of the inclined surface 122 located downstream of the pair of inclined surfaces 122 and the first inclined surface 122A of the inclined surface 122. Fourth, the multiple heat generating parts 31 are formed across the second inclined surface 122B of the inclined surface 122 located downstream of the pair of inclined surfaces 122 and the first inclined surface 122A of the inclined surface 122. In summary, the multiple heat generating portions 31 are formed on the top surface 121 and/or one of the pair of inclined surfaces 122 .

Next, the effects of thermal print head C40 will be explained.

The substrate 1 of the thermal printhead C40 has a main surface 11, a convex portion 12, a pair of end faces 13, and a first surface 14. The first surface 14 is located between at least one of the pair of end faces 13 and the convex portion 12 in the x direction, and is located closer to the main surface 11 than the top surface 121 of the convex portion 12 in the z direction. The thermal printhead C40 has a connection wiring (first connection wiring 63) that is conductive to the wiring layer 4 and spans the first surface 14. Therefore, the thermal printhead C40 also makes it possible to achieve miniaturization. Furthermore, the thermal printhead C40 has a configuration in common with the thermal printhead C10, and thereby achieves the same effects as the thermal printhead C10.

In the thermal printhead C40, each of the pair of inclined surfaces 122 of the convex portion 12 includes a first inclined surface 122A and a second inclined surface 122B. The first inclined surface 122A is connected to the main surface 11 of the substrate 1. The second inclined surface 122B is connected to the top surface 121 of the convex portion 12 and the first inclined surface 122A. In each of the pair of inclined surfaces 122, the inclination angle α2 of the second inclined surface 122B with respect to the main surface 11 is smaller than the inclination angle α1 of the first inclined surface 122A with respect to the main surface 11. By adopting this configuration, the shape of a part of the wiring layer 4 formed along the convex portion 12 becomes smoother. In addition, the occurrence of defects and breaks in the wiring pattern is suppressed in the wiring layer 4 formed along the convex portion 12.

A thermal printhead C50 according to a fifth embodiment of the third aspect will be described with reference to Figures 86 and 87. In these figures, elements that are the same as or similar to those of the thermal printhead C10 described above are given the same reference numerals, and duplicated descriptions will be omitted. Here, the cross-sectional position of Figure 86 is the same as the cross-sectional position of Figure 61, which shows the main part of the thermal printhead C10.

Thermal printhead C50 differs from thermal printhead C10 in that it further comprises a glaze layer 22.

As shown in Figures 86 and 87, the glaze layer 22 is located between the top surface 121 of the convex portion 12 and the insulating layer 21. The glaze layer 22 is made of a material containing glass, for example, amorphous glass. The linear expansion coefficient of the glaze layer 22 is the same as or substantially the same as the linear expansion coefficient of the substrate 1. As shown in Figure 87, the glaze layer 22 bulges in the z direction toward the side toward which the top surface 121 faces. The dimension H of the glaze layer 22 in the z direction is largest at the center of the glaze layer 22 in the y direction.

Next, based on Figure 88, an example of a manufacturing method for thermal printhead C50 will be described.

As in the case of the thermal printhead C10, at least one of the ends in the x direction of the convex portion 12 of the substrate 81 is removed (FIGS. 71 to 73), and then, as shown in FIG. 88, the glaze layer 22 is formed in contact with the top surface 121 of the convex portion 12 of the substrate 81. The glaze layer 22 is formed by supplying a fluid glaze material to the top surface 121 and then baking the glaze material. The glaze material is supplied, for example, by discharging the glaze material from a dispenser. The glaze material includes glass such as amorphous glass. The glaze material may be applied multiple times. Another example of a method for supplying the glaze material is a method of printing the glaze material on the top surface 121 using a screen. After forming the glaze layer 22, as in the case of the thermal printhead C10 described above, the thermal printhead C50 is obtained by going through the same steps as those shown in FIG. 74 to FIG. 80.

Next, the effects of thermal print head C50 will be explained.

The substrate 1 of the thermal printhead C50 has a main surface 11, a convex portion 12, a pair of end faces 13, and a first surface 14. The first surface 14 is located between at least one of the pair of end faces 13 and the convex portion 12 in the x direction, and is located closer to the main surface 11 than the top surface 121 of the convex portion 12 in the z direction. The thermal printhead C50 is provided with a communication wiring (first communication wiring 63) that is conductive to the wiring layer 4 and spans the first surface 14. Therefore, the thermal printhead C50 also makes it possible to achieve miniaturization.

The thermal printhead C50 further includes a glaze layer 22 located between the top surface 121 of the protrusion 12 and the insulating layer 21. The glaze layer 22 bulges in the z direction toward the side toward which the top surface 121 faces. This configuration makes it possible to reduce the contact area of the recording medium 68 with the thermal printhead C50 while suppressing the size of the protrusion 12. Furthermore, the glaze layer 22 has the effect of storing heat generated by the multiple heat generating parts 31. Therefore, the thermal printhead C50 can improve the quality of printing on the recording medium 68 by the multiple heat generating parts 31 while improving the printing energy efficiency.

The present disclosure is not limited to the embodiments relating to the third aspect described above. The specific configurations of each part of the present disclosure can be freely designed in various ways. The embodiments relating to the third aspect of the present disclosure include the configurations described in Supplementary Notes 1C to 21C below.

Appendix 1C.
A substrate having a main surface facing a thickness direction, a pair of end surfaces spaced apart from each other in a main scanning direction, and a protrusion protruding from the main surface in the thickness direction and extending along the main scanning direction;
a resistor layer including a plurality of heat generating portions arranged in the main scanning direction and formed on the main surface and the protruding portions;
a wiring layer in contact with the resistor layer and electrically connected to the heat generating portions;
and a connecting wiring;
The protrusion has a top surface parallel to the main surface,
the base material has a first surface located between at least one of the pair of end surfaces and the convex portion in the main scanning direction and located closer to the main surface than the top surface in the thickness direction;
The interconnection wiring is configured to be electrically connected to the wiring layer and to straddle the first surface.
Appendix 2C.
the protrusion has a pair of inclined surfaces that are connected to the top surface and the main surface and are spaced apart from each other in the sub-scanning direction,
The thermal printhead of claim 1C, wherein the plurality of heat generating portions overlap the top surface when viewed along the thickness direction.
Appendix 3C.
the wiring layer includes a common wiring and a plurality of individual wirings;
the common wiring is located on one side of the plurality of heat generating portions in the sub-scanning direction,
the individual wirings are located on the other side of the heat generating portions in the sub-scanning direction,
a portion of the common wiring is formed on one of the pair of inclined surfaces that is located on the one side in the sub-scanning direction,
a portion of each of the plurality of individual wirings is formed on one of the pair of inclined surfaces that is located on the other side in the sub-scanning direction,
The thermal printhead of claim 2C, wherein the interconnection wiring is electrically connected to the common wiring.
Appendix 4C.
the first surface includes a pair of spaced apart regions located at both ends of the protrusion in the main scanning direction,
The thermal printhead of claim 3C, wherein the interconnection lines span each of the pair of separation regions.
Appendix 5C.
The thermal printhead of claim 3C or 4C, wherein the first surface has a surface roughness greater than a surface roughness of the main surface.
Appendix 6C.
Linear scratches extending along the sub-scanning direction are formed on the first surface,
The thermal printhead described in Appendix 5C, wherein the linear scratches include portions protruding from the main surface in the thickness direction.
Appendix 7C.
The thermal printhead of any one of Appendixes 3C to 6C, wherein the pair of inclined surfaces are inclined so as to approach each other from the main surface to the top surface.
Appendix 8C.
each of the pair of inclined surfaces includes a first inclined surface connected to the main surface and a second inclined surface connected to the top surface and the first inclined surface;
The thermal printhead of claim 7C, wherein an angle of inclination of the second inclined surface with respect to the main surface is smaller than an angle of inclination of the first inclined surface with respect to the main surface.
Appendix 9C.
the substrate is made of a semiconductor material;
The thermal printhead of any one of claims 3C to 8C, wherein the semiconductor material is a single crystal material of silicon.
Appendix 10C.
further comprising an insulating layer covering the main surface and the protrusion,
The thermal printhead of claim 9C, wherein the resistor layer is in contact with the insulating layer.
Appendix 11C.
a glaze layer located between the top surface and the insulating layer;
The thermal printhead of claim 10, wherein the glaze layer bulges in the thickness direction in the direction in which the top surface faces.
Appendix 12C.
The thermal printhead of claim 11C, wherein the glaze layer is made of a material including glass.
Appendix 13C.
The thermal printhead of any one of Appendixes 3C to 12C, further comprising a protective layer covering the plurality of heat generating portions and the wiring layer.
Appendix 14C.
a portion of the protective layer is located on the first surface;
The thermal printhead of claim 13C, wherein the interconnection wiring faces the protective layer.
Appendix 15C.
Further comprising a substrate on which the interconnection wiring is disposed,
The thermal printhead according to any one of Appendixes 3C to 14C, wherein the interconnection wiring is connected to the common wiring.
Appendix 16C.
Further comprising a heat dissipation member,
the substrate has a back surface facing the opposite side to the main surface in the thickness direction,
The back surface is joined to the heat dissipation member,
The thermal printhead of claim 15C, wherein the substrate is supported by the heat dissipation member.
Appendix 17C.
A thermal printhead according to any one of appendices 3C to 16C;
a platen roller disposed opposite the plurality of heat generating portions.
Appendix 18C.
A substrate preparation process for forming a substrate having a main surface facing a thickness direction and a protrusion protruding from the main surface in the thickness direction and extending along a main scanning direction;
a removing step of removing at least one of both ends of the protrusion in the main scanning direction;
forming a resistor layer including a plurality of heat generating portions arranged in the main scanning direction on the main surface and the protruding portion;
forming a wiring layer that is electrically connected to the plurality of heat generating portions in contact with the resistor layer;
A method for manufacturing a thermal printhead comprising:
Appendix 19 C.
The method for manufacturing a thermal printhead described in Appendix 18C, wherein the removing step includes pressing a dicing blade rotating about an axis parallel to the main scanning direction against the convex portion.
Appendix 20C.
the substrate is made of a semiconductor material;
The method of claim 18C or 19C, wherein the semiconductor material is a single crystal silicon material.
Appendix 21C.
The method for manufacturing a thermal printhead described in Appendix 20C, wherein the base material preparation step includes performing anisotropic etching to form the main surface and the convex portion.

[Explanation of symbols according to the third aspect of the embodiment]
C10, C20, C30, C40, C50: Thermal print head 1: Substrate 11: Main surface 12: Convex portion 121: Top surface 122: Inclined surface 122A: First inclined surface 122B: Second inclined surface 123: Boundary 13: End surface 14: First surface 14A: Separated area 141: Linear scratch 15: Back surface 21: Insulating layer 22: Glaze layer 3: Resistor layer 31: Heat generating portion 4: Wiring layer 41: Common wiring 411: Base 412: Extension portion 42: Individual wiring 5: Protective layer 51: First opening 52: Second opening 61: First substrate 611: Inner surface 612: Outer surface 613: Opening 62: Second substrate 621: Mounting surface 63: First interconnection wiring 631: First wiring section 632: Second wiring section 64: Second interconnection wiring 641: Pad section 642: Extension section 65: Driving element 66: Heat dissipation member 67: Third interconnection wiring 68: Recording medium 69: Platen roller 81: Base material 81A: First surface 81B: Second surface 82: Resistor film 83: Conductive layer 88: Dicing blade 891: First mask layer 892: Second mask layer 893: Mask opening

Next, an embodiment relating to the fourth aspect of the present disclosure will be described with reference to Figures 89 to 108.

As described above, in the thermal printhead disclosed in Patent Document 2, a convex portion extending in the main scanning direction and protruding from the main surface is formed on the main surface of the substrate. In addition, a plurality of heat generating portions are arranged on the convex portion along the main scanning direction. In manufacturing such a thermal printhead, it takes a relatively long time to form the convex portions. Therefore, an objective of the fourth aspect of the present disclosure is to provide a thermal printhead that can improve printing quality and manufacturing efficiency.

A thermal printhead D10 according to a first embodiment of the fourth aspect will be described with reference to Figures 89 to 94. The thermal printhead D10 mainly comprises a substrate 1, an insulating layer 2, a resistor layer 3, a wiring layer 4, a protective layer 5, and a coating layer 6. In addition to these, the thermal printhead D10 also comprises a wiring substrate 71, a heat dissipation member 72, a plurality of driving elements 73, a plurality of first wires 74, a plurality of second wires 75, a sealing resin 76, and a connector 77. In Figure 89, for ease of understanding, the protective layer 5 and the coating layer 6 are shown through, and the first wires 74, the second wires 75, and the sealing resin 76 are omitted. In Figures 90 and 91, for ease of understanding, the protective layer 5 and the coating layer 6 are shown through.

As shown in FIG. 92, the substrate 1 of the thermal printhead D10 is joined to a heat dissipation member 72. The wiring board 71 is located next to the substrate 1 in the y direction. The wiring board 71 is fixed to the heat dissipation member 72 in the same manner as the substrate 1. A plurality of heat generating portions 31 (described later) which form part of the resistor layer 3 and are arranged in the x direction are formed on the substrate 1. The plurality of heat generating portions 31 are selectively heated by a plurality of drive elements 73 mounted on the wiring board 71. The plurality of drive elements 73 are driven in accordance with a print signal transmitted from the outside via a connector 77.

As shown in FIG. 92, the thermal print head D10 constitutes a part of the thermal printer 100. As another element, the thermal printer 100 includes a platen roller 79. The platen roller 79 is configured to feed a recording medium 78 such as thermal paper. Printing is performed on the recording medium 78 while the platen roller 79 presses the recording medium 78 against a plurality of heat generating portions 31. As described in the third aspect, other mechanisms that are not roller-shaped (for example, a flat or substantially flat pressing surface) may be used instead of the platen roller 79.

As shown in Fig. 89, the substrate 1 is a strip extending in the x-direction. The substrate 1 is made of a semiconductor material. The semiconductor material is, for example, a single crystal material of silicon (Si).

As shown in Figure 93, the substrate 1 has a main surface 11, a back surface 12, an end surface 13 and an intermediate surface 14. The main surface 11 and the back surface 12 face opposite each other in the z direction. The main surface 11 and the back surface 12 of the substrate 1 both have Miller indices of (100). The main surface 11 and the back surface 12 face opposite each other in the z direction. As shown in Figure 92, in the thermal print head D10, the back surface 12 faces the heat dissipation member 72.

As shown in Figure 93, the end surface 13 of the substrate 1 faces in the y direction. The end surface 13 is connected to the back surface 12. The intermediate surface 14 is connected to the main surface 11 and the end surface 13. The intermediate surface 14 includes an inclined region 14A inclined with respect to the main surface 11. As shown in Figure 93, in the thermal printhead D10, the inclined region 14A corresponds to the entire intermediate surface 14. As shown in Figures 93 and 94, the inclined region 14A is inclined at an inclination angle α with respect to the main surface 11. The surface roughness of the end surface 13 is greater than the surface roughness of the intermediate surface 14.

As shown in FIG. 93, the insulating layer 2 covers the main surface 11 and the intermediate surface 14 of the substrate 1. The insulating layer 2 is located between the substrate 1 and the resistor layer 3. The insulating layer 2 electrically insulates the substrate 1 from the resistor layer 3 and the wiring layer 4. The insulating layer 2 is made of silicon dioxide (SiO ₂ ) using tetraethyl orthosilicate (TEOS) as a raw material, for example. An example of the thickness of the insulating layer 2 is 1 μm or more and 15 μm or less. An end surface 13 of the substrate 1 is exposed from the insulating layer 2.

As shown in FIG. 93, the resistor layer 3 is formed on the main surface 11 and the intermediate surface 14 of the substrate 1. Alternatively, the resistor layer 3 may be formed only on the intermediate surface 14. The resistor layer 3 is in contact with the insulating layer 2. The resistor layer 3 is made of, for example, tantalum nitride (TaN). An example of the thickness of the resistor layer 3 is 0.02 μm or more and 0.1 μm or less. The end surface 13 of the substrate 1 is exposed from the resistor layer 3. In the example shown in FIG. 93, the entire end surface 13 is not covered by the resistor layer 3. In addition, it is preferable that the tip portion of the resistor layer 3 on the intermediate surface 14 (the portion located most downstream in a certain layer (resistor layer 3 in this case)) is covered by the protective layer 5. In this case, the resistor layer 3 to which the voltage is applied is not exposed at the tip surface of the thermal print head D10 (the surface located most downstream in the thermal print head D10 and including the end surface 13). This configuration ensures safety when using the thermal printhead D10.

90, 91 and 93, the resistor layer 3 includes a plurality of heat generating portions 31. In the resistor layer 3, the plurality of heat generating portions 31 are exposed from the wiring layer 4. When the plurality of heat generating portions 31 are selectively energized from the wiring layer 4, the plurality of heat generating portions 31 locally heat the recording medium 78. The plurality of heat generating portions 31 are arranged in the x direction. Of the plurality of heat generating portions 31, two adjacent heat generating portions 31 in the x direction are located apart from each other. When viewed along the z direction, the plurality of heat generating portions 31 overlap the inclined region 14A (intermediate surface 14) of the substrate 1. As shown in FIG. 92, in the thermal printer 100, the plurality of heat generating portions 31 face the platen roller 79.

As shown in FIG. 93, the wiring layer 4 is formed in contact with the resistor layer 3. The wiring layer 4 forms a conductive path for passing electricity through the multiple heating parts 31 of the resistor layer 3. The electrical resistivity of the wiring layer 4 is smaller than that of the resistor layer 3. The wiring layer 4 is a metal layer made of, for example, copper (Cu). An example of the thickness of the wiring layer 4 is 0.3 μm or more and 2.0 μm or less. In addition, the wiring layer 4 may be configured to be made of two metal layers, a titanium (Ti) layer laminated on the resistor layer 3 and a copper layer laminated on the titanium layer. In this case, an example of the thickness of the titanium layer is 0.1 μm or more and 0.2 μm or less. The wiring layer 4 is formed on the main surface 11 and the intermediate surface 14 of the substrate 1. The wiring layer 4 is located away from the boundary 15 between the intermediate surface 14 and the end surface 13 of the substrate 1. The end surface 13 is exposed from the wiring layer 4. 93, the end surface 13 is not entirely covered by the wiring layer 4. In addition, the tip of the wiring layer 4 at the intermediate surface 14 is covered by the protective layer 5. This results in a configuration in which the wiring layer 4 to which a voltage is applied is not exposed at the tip surface of the thermal printhead D10. This configuration ensures safety when using the thermal printhead D10.

In the thermal printhead D10, as shown in FIG. 90 and FIG. 91, the wiring layer 4 includes a common wiring 41, a plurality of individual wirings 42, and a plurality of relay wirings 43. Each of these is electrically connected to one of the plurality of heat generating parts 31. Of these, the common wiring 41 and each of the plurality of individual wirings 42 include a portion formed on the main surface 11 of the substrate 1 and a portion formed on the intermediate surface 14 of the substrate 1. The common wiring 41 and the plurality of individual wirings 42 are located on the side where the main surface 11 is located relative to the plurality of heat generating parts 31 in the y direction (upstream side in the y direction). The plurality of relay wirings 43 are located on the opposite side of the common wiring 41 and the plurality of individual wirings 42 relative to the plurality of heat generating parts 31 in the y direction (downstream side in the y direction). The plurality of relay wirings 43 are formed on the intermediate surface 14.

90 and 91, the common wiring 41 has a base 411 and a plurality of extensions 412. The base 411 is located upstream in the y direction from the plurality of individual wirings 42. The base 411 is strip-shaped extending in the x direction. The plurality of extensions 412 are strip-shaped extending from the downstream end of the base 411 in the y direction toward the plurality of heat generating parts 31. The plurality of extensions 412 are arranged along the x direction. A portion of each of the plurality of extensions 412 is formed on the intermediate surface 14 of the substrate 1. Each of the plurality of extensions 412 is conductive to one of the plurality of heat generating parts 31. In the common wiring 41, a current flows from the base 411 to the plurality of heat generating parts 31 via the plurality of extensions 412.

90 and 91, each of the multiple individual wirings 42 has a pad portion 421 and an extension portion 422. The pad portion 421 is located on the upstream side of the y direction in each of the multiple individual wirings 42. The extension portion 422 is a strip extending from the pad portion 421 toward the multiple heat generating portions 31. The extension portions 422 of the multiple individual wirings 42 are arranged along the x direction. A part of the extension portion 422 is formed on the intermediate surface 14 of the substrate 1. The extension portion 422 is conductive to one of the multiple heat generating portions 31. In the x direction, the extension portion 422 is adjacent to one of the multiple extension portions 412 of the common wiring 41. In each of the multiple individual wirings 42, a current flows from one of the multiple heat generating portions 31 to the pad portion 421 via the extension portion 422.

90 and 91, each of the multiple relay wirings 43 is conductive to two adjacent heat generating parts 31 among the multiple heat generating parts 31. One of the two heat generating parts 31 is conductive to one of the multiple extension parts 412 of the common wiring 41. The other of the two heat generating parts 31 is conductive to one of the extension parts 422 of the multiple individual wirings 42. As a result, each of the multiple relay wirings 43 is conductive to the common wiring 41 and one of the multiple individual wirings 42 through the two heat generating parts 31. In each of the multiple relay wirings 43, a current flows from one of the two heat generating parts 31 that is conductive to one of the multiple extension parts 412 of the common wiring 41 to the other of the two heat generating parts 31 that is conductive to one of the extension parts 422 of the multiple individual wirings 42. The two heat generating portions 31 correspond to one point (dot) formed on the recording medium 78 .

As shown in FIG. 93, the protective layer 5 covers the plurality of heat generating parts 31 of the resistor layer 3 and the wiring layer 4. The protective layer 5 has electrical insulation properties. The protective layer 5 contains silicon. The protective layer 5 is made of, for example, silicon dioxide, silicon nitride (Si ₃ N ₄ ), or silicon carbide (SiC). Alternatively, the protective layer 5 may be a laminate made of a plurality of types of these materials. An example of the thickness of the protective layer 5 is 1.0 μm or more and 10 μm or less. In the thermal printer 100, the recording medium 78 is pressed against the region of the protective layer 5 that covers the plurality of heat generating parts 31 by the platen roller 79 shown in FIG. 92. The end surface 13 of the substrate 1 is exposed from the protective layer 5.

93, a wiring opening 51 is provided in the protective layer 5. The wiring opening 51 penetrates the protective layer 5 in the z-direction. From the wiring opening 51, the pad portions 421 of the multiple individual wirings 42 and a portion of each of the extension portions 422 of the multiple individual wirings 42 are exposed.

As shown in Figure 93, the coating layer 6 covers the protective layer 5. When viewed along the z direction, the coating layer 6 overlaps the heating portion 31 of the resistor layer 3. The coating layer 6 is made of, for example, silicon carbide. The end surface 13 of the substrate 1 is exposed from the coating layer 6.

As shown in FIG. 92, the wiring board 71 is located upstream in the y direction with respect to the substrate 1. As shown in FIG. 89, when viewed along the z direction, the multiple individual wirings 42 are located between the multiple heat generating portions 31 of the resistor layer 3 and the wiring board 71 in the y direction. When viewed along the z direction, the area of the wiring board 71 is larger than the area of the substrate 1. Furthermore, when viewed along the z direction, the wiring board 71 is rectangular with the x direction as the longitudinal direction. The wiring board 71 is, for example, a PCB substrate. The wiring board 71 is mounted with multiple driving elements 73 and a connector 77.

As shown in FIG. 92, the heat dissipation member 72 faces the rear surface 12 of the substrate 1. The rear surface 12 is joined to the heat dissipation member 72. The wiring board 71 is fixed to the heat dissipation member 72 by fastening members such as screws. When the thermal printhead D10 is in use, a portion of the heat generated from the multiple heat generating portions 31 of the resistor layer 3 is conducted to the heat dissipation member 72 via the substrate 1. The heat conducted to the heat dissipation member 72 is dissipated to the outside. The heat dissipation member 72 is made of, for example, aluminum (Al).

As shown in FIG. 89 and FIG. 92, the driving elements 73 are mounted on the wiring board 71 via an electrically insulating die bonding material (not shown). Each of the driving elements 73 is a semiconductor element in which various circuits are configured. Each of the driving elements 73 is bonded to one end of each of the first wires 74 and one end of each of the second wires 75. The other end of each of the first wires 74 is individually bonded to the pad portions 421 of the individual wirings 42. The other end of each of the second wires 75 is bonded to a wiring (not shown) provided on the wiring board 71 and conductive to the connector 77. As a result, a print signal, a control signal, and a voltage (including a ground potential) that operates each of the driving elements 73 are input from the outside to the driving elements 73 via the connector 77. The driving elements 73 selectively apply a voltage to the individual wirings 42 based on these electrical signals. As a result, the heating parts 31 selectively generate heat.

As shown in FIG. 92, the sealing resin 76 covers the multiple driving elements 73, the multiple first wires 74, and the multiple second wires 75, as well as parts of the substrate 1 and the wiring substrate 71. The sealing resin 76 has electrical insulation properties. The sealing resin 76 is, for example, a black, soft synthetic resin used as an underfill. Alternatively, the sealing resin 76 may be a black, hard synthetic resin.

As shown in Figures 89 and 92, the connector 77 is mounted on one end of the wiring board 71 in the y direction. The connector 77 is connected to a control unit (not shown) of the thermal printer 100. The connector 77 has a plurality of pins. Some of the plurality of pins are conductive to wiring (not shown) on the wiring board 71 to which the plurality of second wires 75 are joined. Furthermore, another portion of the plurality of pins is conductive to wiring (not shown) on the wiring board 71 that is conductive to the base 411 of the common wiring 41. A printing voltage (including ground potential) applied to the plurality of heat generating parts 31 is supplied to yet another portion of the plurality of pins.

Next, based on Figures 95 to 103, an example of a manufacturing method for thermal printhead D10 will be described.

As shown in Figures 95 and 96, a groove portion 813 is formed in the substrate 81.

Specifically, as shown in FIG. 95, a first mask layer 891 covering the substrate 81 and a second mask layer 892 covering a part of the first mask layer 891 are formed. The substrate 81 is made of a semiconductor material. The semiconductor material is, for example, a single crystal material of silicon. The substrate 81 is a silicon wafer. In a direction perpendicular to the z direction, a plurality of regions corresponding to a plurality of substrates 1 are connected together to form the substrate 81. The substrate 81 has a main surface 811 and a back surface 812. The main surface 811 and the back surface 812 face opposite each other in the z direction. The main surface 811 and the back surface 812 of the substrate 81 are both surfaces with Miller indices (100). The first mask layer 891 is formed to cover the main surface 811 and the back surface 812. The first mask layer 891 is made of silicon dioxide. The second mask layer 892 is formed to cover the region of the first mask layer 891 covering the main surface 811. The second mask layer 892 is made of silicon nitride. A mask opening 893 penetrating in the z direction is formed in the region of the first mask layer 891 covering the main surface 811 and in the second mask layer 892 covering this region.

When forming the first mask layer 891 and the second mask layer 892, first, a thin film of silicon dioxide is formed by thermal oxidation to cover the main surface 811 and the back surface 812. Next, a thin film of silicon nitride is formed by thermal CVD (Chemical Vapor Deposition) to cover the area of the first mask layer 891 that covers the main surface 811. Finally, a part of the area of the thin film of silicon dioxide covering the main surface 811 and a part of the thin film of silicon nitride covering the area are removed by lithography patterning and reactive ion etching (RIE). As a result, the first mask layer 891 and the second mask layer 892 are formed, and mask openings 893 are formed in the area of the first mask layer 891 covering the main surface 811 and in the second mask layer 892 covering the area.

As the first mask layer 891, a thin film of silicon nitride covering the main surface 811 and the back surface 812 may be formed by thermal CVD. In this case, lithographic patterning and reactive ion etching are used to form a predetermined area on the main surface 811 that is covered by the first mask layer 891, and a mask opening 893 that is an area other than that area where the main surface 811 is exposed.

96, a groove 813 is formed in the substrate 81. The groove 813 is formed by wet etching the area of the main surface 811 of the substrate 81 exposed by the mask opening 893 shown in FIG. 96 using an aqueous potassium hydroxide (KOH) solution. The etching is anisotropic. Finally, the first mask layer 891 and the second mask layer 892 are removed by wet etching using hydrofluoric acid (HF). Thus, the groove 813 is formed in the substrate 81. The groove 813 is recessed from the main surface 811 in the z direction and extends along the x direction. The groove 813 is defined by a pair of inclined surfaces 814 and a bottom surface 815. The pair of inclined surfaces 814 are connected to the main surface 811 and face each other in the y direction. The inclination angles α of the pair of inclined surfaces 814 with respect to the main surface 11 are equal to each other. The bottom surface 815 is located between the main surface 811 and the back surface 812 in the z direction, and is connected to the pair of inclined surfaces 814. In this manner, the groove portion 813 is formed by forming the pair of inclined surfaces 814 and the bottom surface 815 in the base material 81 by anisotropic etching.

After forming the grooves 813 in the substrate 81, a thin film of silicon dioxide covering the main surface 11 may be formed by thermal oxidation. A metal layer may be laminated by plating on the pads 421 of the multiple individual wirings 42 to which the multiple first wires 74 are individually bonded. The thin film of silicon dioxide has the effect of suppressing abnormal growth of the metal layer when the metal layer is laminated by plating.

97, an insulating layer 2 is formed to cover the main surface 11, the pair of inclined surfaces 814, and the bottom surface 815 of the substrate 81. The insulating layer 2 is formed by laminating a thin film of silicon dioxide formed by plasma CVD using tetraethyl orthosilicate (TEOS) as a raw material gas onto the substrate 81 multiple times.

Next, as shown in Figures 98 to 100, the resistor layer 3 and the wiring layer 4 are formed. The resistor layer 3 includes a plurality of heat generating portions 31 arranged in the x-direction. The wiring layer 4 is electrically connected to the plurality of heat generating portions 31.

As shown in Figure 98, a resistor film 82 is formed on a substrate 81. The resistor film 82 is formed so as to cover the entire surface of the insulating layer 2. The resistor film 82 is formed by laminating a thin film of tantalum nitride on the insulating layer 2 by a sputtering method.

Next, as shown in Fig. 99, a conductive layer 83 is formed to cover the entire surface of the resistor film 82. The conductive layer 83 is formed by laminating a thin copper film multiple times on the resistor film 82 by a sputtering method. Alternatively, the conductive layer 83 may be formed by laminating a thin titanium film on the resistor film 82 by a sputtering method, and then laminating a thin copper film multiple times on the thin titanium film by a sputtering method.

100, the conductive layer 83 is lithographically patterned, and then a portion of the conductive layer 83 is removed. The removal is performed by wet etching using a mixed solution of sulfuric acid ( _{H2SO4 )} and hydrogen _peroxide ( _H2O2 ). As a result, the wiring layer 4 is formed in contact with the resistor film 82. In addition, a plurality of heating portions 31 of the resistor layer 3 are formed on a pair of inclined surfaces 814 of the substrate 81.

Next, as shown in FIG. 101, a protective layer 5 is formed to cover the multiple heating parts 31 of the resistor layer 3 and the wiring layer 4. The protective layer 5 is formed by laminating a thin film of silicon nitride on the multiple heating parts 31 and the wiring layer 4 by plasma CVD. Furthermore, in this process, a wiring opening 51 shown in FIG. 93 is formed in the protective layer 5. The wiring opening 51 is formed by removing a part of the protective layer 5 after lithographic patterning is performed on the protective layer 5. The removal is performed by reactive ion etching. As a result, a part of the multiple individual wirings 42 (the pad parts 421 of the multiple individual wirings 42 shown in FIG. 93 and a part of each of the extension parts 422 of the multiple individual wirings 42) is exposed from the wiring opening 51. A part of each of the multiple individual wirings 42 and a part exposed from the wiring opening 51 forms a pad part 421 to which the multiple first wires 74 are individually bonded by wire bonding, for example. A metal layer such as gold may be laminated by plating on each portion (including pad portion 421) of the plurality of individual wirings 42 exposed from wiring opening 51.

Next, as shown in Fig. 102, a coating layer 6 is formed to cover the protective layer 5. The coating layer 6 is formed by laminating a thin film of silicon carbide onto the protective layer 5 by plasma CVD. In this process, the coating layer 6 is made to overlap the multiple heating portions 31 of the resistor layer 3 when viewed along the z direction.

Next, as shown in FIG. 103, the substrate 81 is cut in the z direction. A dicing blade 88 containing abrasive grains is used to cut the substrate 81. In this process, the groove portion 813 of the substrate 81 is divided in the y direction. In this process, the cut substrate 81 becomes the substrate 1, and the substrate 1 has a main surface 11, a back surface 12, an end surface 13, and an intermediate surface 14. The main surface 11 corresponds to a part of the main surface 811 of the substrate 81. The back surface 12 corresponds to a part of the back surface 812 of the substrate 81. The end surface 13 corresponds to the cut surface of the substrate 81 in this process. The intermediate surface 14 corresponds to a part of either of a pair of inclined surfaces 814 of the substrate 81. Therefore, in this process, a main part of the thermal printhead D10 including the substrate 1 is obtained. The reason why the surface roughness of the end face 13 is greater than the surface roughness of the intermediate face 14 is because the end face 13 is a cut surface of the substrate 81 and is a processed surface that includes processing marks caused by abrasive grains, whereas the intermediate face 14 is a processed surface in which a portion of the substrate 81 has been removed by anisotropic etching.

In the process of cutting the substrate 81 in the z-direction, a laser beam may be used. In this process, a crack, a groove, or a plurality of blind holes arranged in a line at a predetermined interval is formed in the main surface 811 of the substrate 81 by a laser beam, and then the substrate 81 is cut by applying an external force to the substrate 81. In this process, an end surface 13 having a surface roughness greater than that of the intermediate surface 14 is obtained.

Next, a plurality of drive elements 73 and a connector 77 are mounted on the wiring board 71. Next, the rear surface 12 of the substrate 1 and the wiring board 71 are bonded to the heat dissipation member 72. Next, a plurality of first wires 74 and a plurality of second wires 75 are bonded to the wiring board 71. Finally, a sealing resin 76 is formed on the substrate 1 and the wiring board 71 to cover the drive elements 73, the plurality of first wires 74, and the plurality of second wires 75. Through the above steps, the thermal printhead D10 is obtained.

Next, based on Figure 104, we will explain thermal print head D11, which is a modified example of thermal print head D10.

104, in the thermal printhead D11, the configuration of the intermediate surface 14 is different from that of the thermal printhead D10. The intermediate surface 14 of the thermal printhead D11 includes an inclined region 14A and a protruding region 14B. The inclined region 14A is connected to the main surface 11. The protruding region 14B is connected to the end surface 13 and the inclined region 14A. The protruding region 14B faces the same side as the main surface 11 in the z direction. The protruding region 14B and the inclined region 14A are covered by the insulating layer 2. In the thermal printhead D11, too, the surface roughness of the end surface 13 is greater than the surface roughness of the intermediate surface 14. The intermediate surface 14 of the thermal printhead D11 is obtained by cutting the substrate 81 so that a part of the bottom surface 815 remains in the process of cutting the substrate 81 in the z direction (see FIG. 103) in the manufacturing process of the thermal printhead D10.

Next, based on Figure 105, a modified manufacturing method for thermal printhead D10 will be described.

As a variation of the process of forming a groove portion 813 in the substrate 81 (see Figures 96 and 97) in the manufacturing process of the thermal printhead D10, there is a method of forming a groove portion 813 in the substrate 81 as shown in Figure 105. The groove portion 813 is formed by forming only a pair of inclined surfaces 814 in the substrate 81 by anisotropic etching. The lower ends of each of the pair of inclined surfaces 814 are connected to each other. The groove portion 813 is defined only by the pair of inclined surfaces 814.

Next, the effects of the thermal print head D10 will be explained.

The thermal printhead D10 has an end surface 13 facing the y direction, and an intermediate surface 14 including an inclined region 14A inclined with respect to the main surface 11 and connected to the main surface 11 and the end surface 13. When viewed along the z direction, the multiple heat generating parts 31 of the resistor layer 3 overlap the inclined region 14A. This allows the recording medium 78 to be in contact with a small area on the inclined region 14A when using the thermal printhead D10. This allows the heat generated by the multiple heat generating parts 31 to be efficiently conducted to the recording medium 78. Therefore, according to the thermal printhead D10, firstly, the amount of heat generated from the multiple heat generating parts 31 required for printing on the recording medium 78 is relatively small, so that power consumption can be reduced. Secondly, print quality can be improved.

In the thermal printhead D10, the end surface 13 of the substrate 1 is exposed from both the resistor layer 3 and the wiring layer 4. Such a configuration of the end surface 13 can be obtained in the manufacture of the thermal printhead D10 by including a process for forming a groove portion 813 in the substrate 81 shown in Figures 95 and 96 and a process for cutting the substrate 81 in the z-direction shown in Figure 103.

95 and 96, in the step of forming grooves 813 in substrate 81, a pair of inclined surfaces 814 that define at least a portion of grooves 813 are formed in substrate 81. In the subsequent step of forming resistor layer 3 (see FIGS. 98 to 100), resistor layer 3 is formed on the pair of inclined surfaces 814. This allows thermal printhead D10 to have a substrate 1 having an intermediate surface 14 that includes inclined region 14A, and a configuration in which multiple heating portions 31 overlap inclined region 14A when viewed along the z direction.

When forming a pair of inclined surfaces 814 on the substrate 81 to improve the printing quality, the time required to form the pair of inclined surfaces 814 is shorter when forming a groove portion 813 recessed in the z direction from the main surface 811 than when forming a convex portion protruding in the z direction from the main surface 811 of the substrate 81. This is because the volume of the substrate 81 removed in forming the pair of inclined surfaces 814 is smaller when forming the groove portion 813 than when forming the convex portion. Furthermore, when cutting the substrate 81 in the z direction, the groove portion 813 is divided in the y direction, so that the number of main parts of the thermal printhead D10 manufactured is doubled. Therefore, according to the manufacturing method of the thermal printhead D10, it is possible to improve the manufacturing efficiency, and the end surface 13 of the substrate 1 can be said to be a trace during the manufacturing of the thermal printhead D10 with improved manufacturing efficiency. As described above, according to the thermal printhead D10, it is possible to achieve both improved printing quality and improved manufacturing efficiency of the thermal printhead.

The substrate 81 is made of a semiconductor material (single crystal silicon material). This allows a pair of inclined surfaces 814 to be formed on the substrate 81 by anisotropic etching.

The substrate 1 is made of a semiconductor material (single crystal silicon material). This gives the substrate 1 a relatively high thermal conductivity (approximately 170 W/(m·K)), which improves the heat dissipation of the thermal printhead D10. Furthermore, the end face 13 of the substrate 1 being exposed to the outside contributes to improved heat dissipation. In this case, the surface roughness of the end face 13 being greater than the surface roughness of the intermediate face 14 of the substrate 1 leads to an increase in the surface area of the end face 13, making the improvement in the heat dissipation of the thermal printhead D10 more effective. In addition, the improved heat dissipation of the thermal printhead D10 contributes to faster printing speeds.

The wiring layer 4 includes a portion formed on the intermediate surface 14, and is located away from the boundary 15 between the intermediate surface 14 and the end surface 13. As a result, in the process of cutting the substrate 81 in the z-direction shown in FIG. 105, the substrate 81 is cut without the dicing blade 88 coming into contact with the wiring layer 4. This makes it possible to prevent the wiring layer 4 from breaking in this process.

The thermal printhead D10 further includes a protective layer 5 that covers the multiple heat generating portions 31 and the wiring layer 4. This allows the multiple heat generating portions 31 and the wiring layer 4 to be protected by the protective layer 5, and also allows the recording medium 78 to come into contact with the thermal printhead D10 more smoothly when the thermal printhead D10 is in use.

The thermal printhead D10 has a coating layer 6 that covers the protective layer 5. When viewed along the z direction, the coating layer 6 overlaps multiple heat generating portions 31. This results in a configuration in which the recording medium 78 comes into contact with the coating layer 6 when the thermal printhead D10 is in use. This makes it possible to suppress wear of the protective layer 5 caused by the feeding of the recording medium 78.

The thermal printhead D10 further includes a heat dissipation member 72. The rear surface 12 of the substrate 1 is joined to the heat dissipation member 72. This allows a portion of the heat generated from the multiple heat generating parts 31 to be quickly dissipated to the outside via the substrate 1 and the heat dissipation member 72 when the thermal printhead D10 is in use.

A thermal printhead D20 according to a second embodiment of the fourth aspect of the present disclosure will be described with reference to Figures 106 to 108. In these figures, elements that are the same as or similar to those of the thermal printhead D10 described above are given the same reference numerals, and duplicated descriptions will be omitted. In Figure 106, for ease of understanding, the protective layer 5 and the covering layer 6 are shown through, and the multiple first wires 74, the multiple second wires 75, and the sealing resin 76 are not shown. In Figures 107 and 108, for ease of understanding, the protective layer 5 and the covering layer 6 are shown through.

In thermal printhead D20, the configuration of the wiring layer 4 differs from that of the thermal printhead D10 described above.

As shown in Figures 106 to 108, in thermal printhead D20, the wiring layer 4 includes a common wiring 41 and multiple individual wirings 42, but does not include multiple relay wirings 43. The common wiring 41 is located on the side where the end face 13 of the substrate 1 is located relative to the multiple heat generating portions 31 of the resistor layer 3 in the y direction (the downstream side in the y direction). The multiple individual wirings 42 are located on the opposite side of the common wiring 41 relative to the multiple heat generating portions 31 in the y direction. The common wiring 41 and a portion of the extension portion 422 of each of the multiple individual wirings 42 are formed on the intermediate surface 14 of the substrate 1.

107 and 108, the base 411 of the common wiring 41 is located furthest downstream in the y direction from the multiple heat generating portions 31. The multiple extension portions 412 of the common wiring 41 are strip-shaped extending from the upstream end of the base 411 in the y direction toward the multiple heat generating portions 31. The multiple heat generating portions 31 are located between the common wiring 41 and the multiple individual wirings 42 in the y direction. When viewed along the z direction, each of the multiple heat generating portions 31 is sandwiched in the y direction between one of the multiple extension portions 412 of the common wiring 41 and one of the extension portions 422 of the multiple individual wirings 42.

Next, the effects of the thermal print head D20 will be explained.

The thermal printhead D20 has an end surface 13 facing the y direction, and an intermediate surface 14 including an inclined region 14A inclined with respect to the main surface 11 and connected to the main surface 11 and the end surface 13. When viewed along the z direction, the multiple heating portions 31 of the resistor layer 3 overlap the inclined region 14A. The end surface 13 is exposed from both the resistor layer 3 and the wiring layer 4. Therefore, the thermal printhead D20 also makes it possible to achieve both improved printing quality and improved manufacturing efficiency of the thermal printhead. Furthermore, by having a configuration similar to that of the thermal printhead D10, it achieves the effects corresponding to that configuration.

In the thermal printhead D20, the multiple heat generating parts 31 are located between the common wiring 41 and the multiple individual wirings 42 in the y direction. In other words, one heat generating part 31 corresponds to one point (dot) formed on the recording medium 78. This allows the number of multiple individual wirings 42 per unit length along the x direction to be increased compared to the configuration of the wiring layer 4 of the thermal printhead D10 (see FIG. 91). Therefore, the number of heat generating parts 31 corresponding to one dot per unit length along the x direction can be increased. Therefore, the number of printed dots (dot density) per unit length along the x direction for printing on the recording medium 78 increases, making it possible to perform more detailed printing on the recording medium 78.

The configuration of the wiring layer 4 provided in each of the thermal printheads D10 and D20 is an example. The configuration of the wiring layer 4 in the present disclosure is not limited to the configuration provided in each of the thermal printheads D10 and D20.

The present disclosure is not limited to the embodiments relating to the fourth aspect described above. The specific configurations of each part of the present disclosure can be freely designed in various ways. Embodiments relating to the fourth aspect of the present disclosure include the configurations described in Supplementary Notes 1D to 16D below.

Appendix 1D.
a substrate having a main surface facing a thickness direction, an end surface facing a sub-scanning direction, and an intermediate surface including an inclined region inclined with respect to the main surface and connected to the main surface and the end surface;
a resistor layer including a plurality of heat generating portions arranged in a main scanning direction and formed on the intermediate surface;
a wiring layer that is electrically connected to the plurality of heat generating portions and is formed in contact with the resistor layer,
When viewed along the thickness direction, the heat generating portions overlap the inclined region,
The end surface of the thermal printhead is exposed from the resistor layer and the wiring layer.
Appendix 2D.
1D. The thermal printhead of claim 1, wherein the end surfaces have a surface roughness greater than a surface roughness of the intermediate surface.
Appendix 3D.
The thermal printhead of claim 1D or 2D, wherein the wiring layer includes a portion formed on the intermediate surface and located away from the boundary between the intermediate surface and the end surface.
Appendix 4D.
the wiring layer includes common wiring and individual wiring,
each of the common wiring and the individual wiring is electrically connected to one of the plurality of heat generating portions;
The thermal printhead of claim 3D, wherein each of the common wiring and the individual wiring includes a portion formed on the intermediate surface.
Appendix 5D.
the common wiring and the individual wiring are located on a side of the main surface with respect to the plurality of heat generating portions in the sub-scanning direction, and are adjacent to each other in the main scanning direction;
the wiring layer includes relay wiring located on an opposite side of the common wiring and the individual wiring with respect to the plurality of heat generating portions in the sub-scanning direction,
The thermal printhead according to claim 4D, wherein the relay wiring is electrically connected to the common wiring and the individual wiring via two adjacent heat generating portions among the plurality of heat generating portions.
Appendix 6D.
the common wiring is located on a side where the end surface is located with respect to the plurality of heat generating portions in the sub-scanning direction,
the individual wiring is located on an opposite side of the common wiring with respect to the plurality of heat generating portions in the sub-scanning direction,
The thermal printhead according to claim 4D, wherein the plurality of heat generating portions are positioned between the common wiring and the individual wiring in the sub-scanning direction.
Appendix 7D.
the substrate is made of a semiconductor material;
The thermal printhead of any preceding claim, wherein the semiconductor material comprises a single crystal material of silicon.
Appendix 8D.
further comprising an insulating layer covering the main surface and the intermediate surface;
the insulating layer is located between the substrate and the resistor layer;
7D. The thermal printhead of claim 7, wherein the end surface is exposed from the insulating layer.
Appendix 9D.
a protective layer covering the plurality of heat generating portions and the wiring layer;
8D. The thermal printhead of claim 1D, wherein the end surface is exposed from the protective layer.
Appendix 10D.
Further comprising a coating layer covering the protective layer,
When viewed along the thickness direction, the coating layer overlaps the plurality of heat generating portions,
The thermal printhead of claim 9D, wherein the end surface is exposed from the covering layer.
Appendix 11D.
Further comprising a heat dissipation member,
the substrate has a back surface facing the opposite side to the main surface in the thickness direction,
The thermal printhead according to any one of claims 1D to 10D, wherein the back surface is joined to the heat dissipation member.
Appendix 12D.
A step of forming a groove portion in a substrate having a main surface facing a thickness direction, the groove portion being recessed from the main surface in the thickness direction and extending along a main scanning direction;
forming a resistor layer on the base material, the resistor layer including a plurality of heat generating portions arranged in the main scanning direction;
forming a wiring layer that is electrically connected to the plurality of heat generating portions in contact with the resistor layer;
In the step of forming the groove portion, a pair of inclined surfaces are formed on the base material, the inclined surfaces are connected to the main surface, face each other in a sub-scanning direction, and define at least a portion of the groove portion;
In the step of forming the resistor layer, the resistor layer is formed on the pair of inclined surfaces,
The method for manufacturing a thermal printhead further comprises, after the step of forming the wiring layer, a step of cutting the base material in the thickness direction so that the groove portion is divided in the sub-scanning direction.
Appendix 13D.
the substrate is made of a semiconductor material;
the semiconductor material comprises a single crystal material of silicon;
The method for manufacturing a thermal printhead according to claim 12D, wherein in the step of forming the groove portion, the pair of inclined surfaces are formed by anisotropic etching.
Appendix 14D.
The method for manufacturing a thermal printhead described in Appendix 13D, further comprising the step of forming an insulating layer covering the main surface and the pair of inclined surfaces after the step of forming the groove portion and before the step of forming the resistor layer.
Appendix 15D.
A method for manufacturing a thermal printhead described in any one of Appendices 12D to 14D, further comprising a step of forming a protective layer covering the multiple heat generating portions and the wiring layer after the step of forming the wiring layer and before the step of cutting the substrate.
Appendix 16D.
The method further includes a step of forming a covering layer that covers the protective layer after the step of forming the protective layer and before the step of cutting the base material,
The method for manufacturing a thermal printhead described in Appendix 15D, wherein in the step of forming the covering layer, the covering layer overlaps the plurality of heat generating portions when viewed along the thickness direction.

[Explanation of symbols according to the fourth aspect]
D10, D20: Thermal print head 1: Substrate 11: Main surface 12: Back surface 13: End surface 14: Intermediate surface 14A: Inclined region 14B: Protruding region 15: Boundary 2: Insulating layer 3: Resistor layer 31: Heat generating portion 4: Wiring layer 41: Common wiring 411: Base portion 412: Extension portion 42: Individual wiring 421: Pad portion 422: Extension portion 43: Relay wiring 5: Protective layer 51: Wiring opening 6: Covering layer 71: Wiring substrate 72: Heat dissipation member 73: Driving element 74: First wire 75: Second wire 76: Sealing resin 77: Connector 78: Recording medium 79: Platen roller 81: Base material 811: Main surface 812: Back surface 813: Groove portion 814: Inclined surface 815: Bottom surface 82: resistor film 83: conductive layer 88: dicing blade 891: first mask layer 892: second mask layer 893: mask opening α: inclination angle

Claims (15)

a semiconductor substrate having a main surface and a back surface spaced apart from each other in a thickness direction, and a first penetrating portion formed therein that penetrates from the main surface to the back surface;
a resistor layer including a plurality of heat generating portions arranged in a main scanning direction and formed on the main surface;
A first electrode formed on the back surface;
a wiring layer formed on the resistor layer and electrically connected to the heat generating portions;
a first through wiring housed in the first through portion;
a plurality of second electrodes and a plurality of second through-wires formed on the rear surface;
a first insulating layer covering the main surface ;
the wiring layer includes a common wiring located on a first side in a sub-scanning direction with respect to the plurality of heat generating portions,
the first through wiring is connected to the common wiring and the first electrode ,
the wiring layer includes a plurality of individual wirings located on a second side in the sub-scanning direction with respect to the plurality of heat generating portions,
the semiconductor substrate is formed with a plurality of second through portions that penetrate from the main surface to the back surface and are located on an opposite side of the first through portions with respect to the plurality of heat generating portions in the sub-scanning direction,
the second through wirings are individually accommodated in the second through portions,
each of the plurality of second through wirings is connected to one of the plurality of individual wirings and one of the plurality of second electrodes;
the semiconductor substrate has a first inner circumferential surface connected to the main surface and the back surface and defining the first penetrating portion, and a plurality of second inner circumferential surfaces connected to the main surface and the back surface and defining each of the plurality of second penetrating portions;
The first insulating layer is in contact with the resistor layer and covers the first inner circumferential surface and the plurality of second inner circumferential surfaces . The main surface includes a base surface and a convex surface that bulges from the base surface in the thickness direction,
the convex surface extends along the main scanning direction,
The thermal printhead according to claim 1 , wherein the plurality of heat generating portions are formed on the convex surface . the convex surface includes a top surface parallel to the base surface, and a pair of inclined surfaces connected to the top surface and the base surface and spaced apart from each other in the sub-scanning direction,
The thermal printhead of claim 2 , wherein the plurality of heat generating portions are formed on the top surface . 4. The thermal printhead according to claim 3, wherein a portion of said common wiring and a portion of each of said plurality of individual wirings are formed on one of said pair of inclined surfaces . 5. The thermal printhead of claim 4, wherein the pair of inclined surfaces are inclined relative to the base surface so as to approach each other from the base surface to the top surface . each of the pair of inclined surfaces includes a first region connected to the base surface and a second region connected to the top surface and the first region;
6. The thermal printhead of claim 5, wherein an inclination angle of the second region relative to the base surface is smaller than an inclination angle of the first region relative to the base surface . A thermal printhead as claimed in any one of claims 2 to 6 , wherein the semiconductor substrate comprises a single crystal material of silicon . A second insulating layer covering the back surface and connected to the first insulating layer is further provided.
8. The thermal printhead according to claim 1 , wherein the first electrode and the plurality of second electrodes are in contact with the second insulating layer . a heat dissipation layer located between the first electrode and the plurality of second electrodes in the sub-scanning direction and formed in contact with the second insulating layer,
The thermal printhead according to claim 8 , wherein the heat dissipation layer overlaps the plurality of heat generating portions when viewed in the thickness direction . a wiring substrate facing the rear surface and having the first electrode and a plurality of second electrodes bonded thereto;
The thermal printhead according to claim 9 , wherein the wiring board has a heat sink to which the heat dissipation layer is joined . 11. The thermal printhead according to claim 1 , further comprising a protective layer covering a part of the main surface, the plurality of heat generating portions, and the wiring layer . forming a first recess in a substrate made of a semiconductor material and having a main surface facing a thickness direction, the first recess being recessed from the main surface in the thickness direction;
forming a resistor layer including a plurality of heat generating portions arranged in a main scanning direction on the main surface and in the first recess;
forming a wiring layer on the resistor layer, the wiring layer being electrically connected to the plurality of heat generating portions;
removing a portion of the base material located on an opposite side to the main surface in the thickness direction;
forming an electrode on the base material, the electrode being located on an opposite side of the base material from the wiring layer in the thickness direction and being electrically connected to the wiring layer;
the step of forming the wiring layer includes a step of forming a common wiring located on a first side in a sub-scanning direction with respect to the plurality of heat generating portions, and a first through wiring accommodated in the first recess and connected to the common wiring;
In the step of removing a portion of the base material, the portion of the base material is removed until a portion of the first through wiring is exposed from the base material;
the step of forming the electrode includes a step of forming a first electrode that is electrically connected to the common wiring;
In the step of forming the first electrode, the first electrode is formed so as to be in contact with the first through wiring. a step of forming a plurality of second recesses, the second recesses being recessed in the thickness direction from the main surface of the base material and positioned on an opposite side to the first recesses with respect to the plurality of heat generating portions in the sub-scanning direction, between the step of forming the first recesses and the step of forming the resistor layer;
In the step of forming the resistor layer, a part of the resistor layer is formed in the plurality of second recesses,
the step of forming the wiring layer includes a step of forming a plurality of individual wirings located on a second side in the sub-scanning direction with respect to the plurality of heat generating portions, and a plurality of second through wirings individually accommodated in the plurality of second recesses and individually connected to the plurality of individual wirings,
In the step of removing a portion of the base material, the portion of the base material is removed until a portion of the plurality of second through wirings is exposed from the base material;
The step of forming the electrodes includes a step of forming a plurality of second electrodes that are individually conductive to the plurality of individual wirings,
The method for manufacturing a thermal printhead according to claim 12 , wherein in the step of forming the plurality of second electrodes, the plurality of second electrodes are formed so as to be in contact with the plurality of second through-hole wirings individually. The main surface includes a base surface and a convex surface that bulges from the base surface in the thickness direction,
The method further includes, before the step of forming the first recess, a step of forming a convex portion on the base material, the convex portion bulging from the base surface in the thickness direction and extending along the main scanning direction and including the convex surface;
The method for manufacturing a thermal printhead according to claim 13 , wherein in the step of forming the resistor layer, the plurality of heat generating portions are formed on the convex surface. The method of claim 14 , wherein the semiconductor material comprises a single crystal material of silicon .

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