JP7803701B2 - Thermal printhead and method for manufacturing the same - Google Patents

Description

This disclosure relates to a thermal printhead and a method for manufacturing a thermal printhead.

Patent Document 1 discloses an example of a conventional thermal printhead. Thermal printheads generally have a number of heat-generating elements arranged in the main scanning direction on a head substrate. Each heat-generating element is formed by laminating an upstream conductive layer and a downstream conductive layer on a resistor layer formed on the head substrate via a heat storage layer, exposing part of the resistor layer. By passing electricity between the upstream electrode layer and the downstream electrode layer, the exposed part of the resistor layer (heat-generating element) generates heat due to Joule heat. The heat storage layer is formed to store the heat generated by the heat-generating elements, enabling high-speed printing.

The thermal printhead disclosed in Patent Document 1 uses silicon (Si) as the substrate, with convex portions formed by anisotropic etching. A heat storage layer is formed on the top surfaces of the convex portions, and an insulating layer, resistor layer, electrode layer, and protective layer are further formed on the convex portions in this order. The resistor layer exposed from the electrode layer on the convex portions constitutes the heating portion. The print medium is transported by a platen roller and printed by being pressed against the heating portion located on the convex portions. The inclination angle α1 of the inclined outer surface connected to the top surfaces of the convex portions relative to the main surface of the substrate is, for example, 50 to 60 degrees. If the print medium is thick, the lower end of the leading edge of the print medium transported by the platen roller may come into contact with the inclined outer surface of the convex portions and become caught.

Japanese Patent Application Laid-Open No. 2021-11021

This disclosure was conceived in light of the above circumstances, and aims to provide a thermal printhead that can prevent the print medium from getting caught on protrusions, as well as a method for manufacturing such a thermal printhead.

A thermal printhead provided by a first aspect of the present disclosure includes a substrate having a main surface facing in one direction in the thickness direction and made of a single-crystal semiconductor; a resistor layer formed on the main surface and including a plurality of heat generating elements arranged in the main scanning direction; an insulating layer formed between the substrate and the resistor layer; and a heat storage layer formed between the substrate and the plurality of heat generating elements and being a glaze made of a glass material. The substrate includes a convex portion protruding from the main surface and extending in the main scanning direction. The convex portion includes an apex having a top surface parallel to the main surface, and an inclined portion connected to the apex and the main surface and inclined relative to the main surface. The inclined portion includes a first inclined surface connected to the main surface and inclined at a first inclination angle relative to the main surface, and a second inclined surface interposed between the first inclined surface and the top surface and inclined at a second inclination angle relative to the main surface. The heat storage layer is formed only on the top surface.

A method for manufacturing a thermal printhead provided by a second aspect of the present disclosure includes a preparation step of preparing a substrate made of a single-crystal semiconductor; a first etching step of performing a first anisotropic etching on the substrate to form a main surface facing in one direction in the thickness direction, a convex portion protruding from the main surface, and two grooves recessed from a top surface parallel to the main surface of the convex portion and extending in the main scanning direction; a heat storage layer formation step of forming a heat storage layer by disposing glass paste in the area between the two grooves on the top surface and firing the paste; The method includes a second etching step in which the base material is subjected to a second anisotropic etching to remove a portion of the convex portion, thereby forming in the convex portion a top surface that is a region of the top surface sandwiched between the two grooves, a first inclined surface that is connected to the main surface and inclined at a first inclination angle with respect to the main surface, and a second inclined surface that is interposed between the first inclined surface and the top surface and inclined at a second inclination angle with respect to the main surface; and a heat generating portion forming step in which a plurality of heat generating portions arranged in the main scanning direction are formed on the heat storage layer.

The thermal printhead disclosed herein can prevent the print medium from getting caught on protrusions.

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 showing a thermal printhead according to a first embodiment of the present disclosure. FIG. 2 is an enlarged plan view of the main part of the thermal printhead shown in FIG. FIG. 3 is an enlarged plan view of the main part of the thermal printhead shown in FIG. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. FIG. 5 is a cross-sectional view of the main part of the thermal printhead shown in FIG. FIG. 6 is an enlarged cross-sectional view of a main part of the thermal printhead shown in FIG. FIG. 7 is a flowchart showing an example of a method for manufacturing the semiconductor device shown in FIG. FIG. 8 is a cross-sectional view showing one step of an example of a method for manufacturing the thermal printhead shown in FIG. FIG. 9 is a cross-sectional view showing one step of an example of a method for manufacturing the thermal printhead shown in FIG. FIG. 10 is a cross-sectional view showing one step of an example of a method for manufacturing the thermal printhead shown in FIG. FIG. 11 is a cross-sectional view showing a step in an example of a method for manufacturing the thermal printhead shown in FIG. FIG. 12 is a cross-sectional view showing a step in an example of a method for manufacturing the thermal printhead shown in FIG. FIG. 13 is a cross-sectional view showing one step of an example of a method for manufacturing the thermal printhead shown in FIG. FIG. 14 is a cross-sectional view showing a step in an example of a method for manufacturing the thermal printhead shown in FIG. FIG. 15 is a cross-sectional view showing a step in an example of a method for manufacturing the thermal printhead shown in FIG. FIG. 16 is a cross-sectional view showing a step in another example of a method for manufacturing the thermal printhead shown in FIG. FIG. 17 is a cross-sectional view showing a step of another example of a method for manufacturing the thermal printhead shown in FIG. FIG. 18 is an enlarged cross-sectional view of a main portion of a thermal printhead according to a second embodiment of the present disclosure. FIG. 19 is an enlarged cross-sectional view of a main portion of a thermal printhead according to a third embodiment of the present disclosure. FIG. 20 is an enlarged cross-sectional view of a main portion of a thermal printhead according to a fourth embodiment of the present disclosure. FIG. 21 is an enlarged cross-sectional view of a main portion of a thermal printhead according to a fifth embodiment of the present disclosure. FIG. 22 is a cross-sectional view showing one step of an example of a method for manufacturing the thermal printhead shown in FIG. FIG. 23 is a cross-sectional view showing a step in an example of a method for manufacturing the thermal printhead shown in FIG.

Preferred embodiments of the present disclosure will now be described in detail with reference to the drawings.

In this disclosure, unless otherwise specified, "an object A is formed on an object B" and "an object A is formed on an object B" include "an object A is formed directly on an object B" and "an object A is formed on an object B with another object interposed between the two objects." Similarly, "an object A is disposed on an object B" and "an object A is disposed on an object B" include "an object A is disposed directly on an object B" and "an object A is disposed on an object B with another object interposed between the two objects." Similarly, unless otherwise specified, "an object A is located on an object B" includes "an object A is located on an object B with an object A in contact with the object B" and "an object A is located on an object B with another object interposed between the two objects." Additionally, unless otherwise specified, "item A overlaps item B when viewed from a certain direction" includes "item A overlaps the entirety of item B" and "item A overlaps part of item B."

First Embodiment
1 to 6 show a thermal printhead according to a first embodiment of the present disclosure. The thermal printhead A1 of this embodiment includes a head substrate 1, a connection substrate 5, multiple wires 61 and 62, multiple driver ICs 7, a protective resin 78, and a heat dissipation member 8. The thermal printhead A1 is incorporated into a printer that prints on a print medium (not shown) transported by a platen roller 99 (see FIG. 4). Examples of print media include thermal paper for creating barcode sheets and receipts.

Figure 1 is a plan view of the thermal printhead A1. Figure 2 is an enlarged plan view of the thermal printhead A1. Figure 3 is an enlarged plan view of the thermal printhead A1. Figure 4 is a cross-sectional view taken along line IV-IV in Figure 1. Figure 5 is a cross-sectional view of the thermal printhead A1, enlarging a portion of Figure 4. Figure 6 is an enlarged cross-sectional view of the thermal printhead A1, enlarging a portion of Figure 5. For ease of understanding, the protective layer 2, described below, is omitted from Figures 1 to 3. For ease of understanding, the protective resin 78 is omitted from Figures 1 and 2. For ease of understanding, the wires 61 are omitted from Figure 2. In these figures, the longitudinal direction (main scanning direction) of the head substrate 1 is defined as the x-direction, the lateral direction (sub-scanning direction) as the y-direction, and the thickness direction as the z-direction. Additionally, with regard to the y direction, the lower side in Figures 1 to 3 (the right side in Figures 4 to 6) is considered to be "upstream," where the print medium is fed in, and the upper side in Figures 1 to 3 (the left side in Figures 4 to 6) is considered to be "downstream," where the print medium is discharged. Furthermore, with regard to the z direction, the upper side in Figures 4 to 6 (the direction indicated by the arrow indicating the z direction) is considered to be "upward," and the opposite direction is considered to be "downward." This also applies to the following figures.

As shown in Figure 4, in the thermal printhead A1, the head substrate 1 and connection substrate 5 are mounted adjacent to each other in the y direction on the heat dissipation member 8. The head substrate 1 has a plurality of heat-generating elements 41 arranged in the x direction, as described in detail below. These heat-generating elements 41 are selectively driven to generate heat by a driver IC 7 mounted on the connection substrate 5, and print on the print medium pressed against the heat-generating elements 41 by the platen roller 99 in accordance with a print signal transmitted from the outside via the connector 59.

As shown in Figures 1 to 6, the head substrate 1 includes a base material 10, a heat storage layer 15, an insulating layer 19, a protective layer 2, an electrode layer 3, and a resistor layer 4.

The substrate 10 is made of a single-crystal semiconductor. Si is a suitable single-crystal semiconductor. As shown in FIG. 1, the substrate 10 has an elongated rectangular shape with the x direction as the longitudinal direction and the y direction as the transverse direction when viewed in the z direction. The size of the substrate 10 is not limited, but as an example, the dimension in the x direction is, for example, 20 mm to 300 mm, the dimension in the y direction is, for example, 1.0 mm to 5.0 mm, and the dimension in the z direction is, for example, 725 μm. The side of the substrate 10 closer to the driver IC 7 in the y direction is the upstream side, and the side farther from the driver IC 7 is the downstream side. The print medium is transported from the upstream side to the downstream side in the y direction by a platen roller 99.

As shown in Figures 1, 2, 5, and 6, the substrate 10 has a main surface 11 and protrusions 12. The main surface 11 faces upward in the z-direction. In the present disclosure, the main surface 11 extends along the x-y plane (a plane defined by the x and y directions, and similarly applies to other planes) and is a plane substantially parallel to the x-y plane. The main surface 11 is a (100) plane. The protrusions 12 protrude from the main surface 11 in the z-direction and extend in the x-direction. The protrusions 12 are formed toward the downstream side of the main surface 11. The cross-sectional shape of the protrusions 12 along the y-z plane is uniform in the x-direction. Hereinafter, the cross-section along the y-z plane will be referred to as the "y-z cross-section." The y-direction dimension W1 of the protrusions 12 at the lower end in the z-direction is, for example, approximately 500 μm, and the y-direction dimension W2 at the upper end in the z-direction is, for example, approximately 200 μm. Although dimensions W1 and W2 are not limited, in this embodiment, dimension W1 is between two and ten times dimension W2. Furthermore, dimension H1 in the z direction of protrusion 12 is, for example, approximately 150 μm. As shown in FIG. 6, protrusion 12 includes a peak 13 and a pair of inclined portions 14.

As shown in Figures 5 and 6, the apex 13 is a portion of the convex portion 12 that is relatively far from the main surface 11 in the z direction. The apex 13 has a top surface 131 that is parallel to the main surface 11. The top surface 131 is substantially flat. When viewed in the z direction, the top surface 131 has an elongated rectangular shape that extends elongately in the x direction. The dimension H1 is the distance in the z direction between the top surface 131 and the main surface 11.

As shown in Figures 5 and 6, the pair of inclined portions 14 are portions of the convex portion 12 that are inclined relative to the main surface 11 and the top surface 131 so that their positions become lower as they move away from the apex 13 in the y direction. Each of the pair of inclined portions 14 is connected to the main surface 11 and the apex 13 and is sandwiched between them in the y direction. The pair of inclined portions 14 includes an inclined portion 14 on the upstream side and an inclined portion 14 on the downstream side relative to the apex 13. As shown in Figure 6, each of the pair of inclined portions 14 has a first inclined surface 141, a second inclined surface 142, and a third inclined surface 143. The first inclined surface 141, the second inclined surface 142, and the third inclined surface 143 are aligned in the y direction. The first inclined surface 141, the second inclined surface 142, and the third inclined surface 143 are all inclined relative to the main surface 11 and the top surface 131.

The first inclined surface 141 connects to the main surface 11 and the second inclined surface 142 in the y direction and is inclined at a first inclination angle α1 with respect to the main surface 11. In this embodiment, the first inclined surface 141 is a (111) plane, and the first inclination angle α1 is, for example, 54.8°. The second inclined surface 142 connects to the first inclined surface 141 and the third inclined surface 143 in the y direction and is inclined at a second inclination angle α2 with respect to the main surface 11. The second inclination angle α2 is smaller than the first inclination angle α1 and, in this embodiment, is, for example, 31°. The third inclined surface 143 connects to the second inclined surface 142 and the top surface 131 in the y direction and is inclined at a third inclination angle α3 with respect to the main surface 11. The third inclination angle α3 is larger than the second inclination angle α2. In this embodiment, the third inclined surface 143 is a (111) plane, and the third inclination angle α3 is the same as the first inclination angle α1, for example, 54.8°. The dimension of the third inclined surface 143 in the direction perpendicular to the x-direction is sufficiently smaller than those of the first inclined surface 141 and the second inclined surface 142. Note that the first inclined angle α1, the second inclined angle α2, and the third inclined angle α3 are not limited. It is sufficient that the second inclined angle α2 is smaller than the first inclined angle α1, and the third inclined angle α3 is larger than the second inclined angle α2.

The heat storage layer 15 is a glaze made of a glass material such as amorphous glass. The glaze (heat storage layer 15) is formed, for example, by firing a glass paste. In this embodiment, the thermal expansion coefficient of the heat storage layer 15 is similar to that of Si, the material of the substrate 10. The characteristics of the glass material of the heat storage layer 15 are not limited. As shown in Figures 5 and 6, the heat storage layer 15 is disposed on the top 13 of the convex portion 12. The heat storage layer 15 is in contact with the top surface 131, and in this embodiment, the heat storage layer 15 is not in contact with the first inclined surface 141, the second inclined surface 142, or the third inclined surface 143. The heat storage layer 15 is formed only on the top surface 131. The heat storage layer 15 extends in the x direction and is formed across the entire width of the top surface 131 in the y direction.

In this embodiment, as shown in the manufacturing method described below, the heat storage layer 15 is formed by a process in which glass paste is applied using a dispenser and then fired. There is no limit to the number of times the glass paste is applied; it may be applied and fired just once, or it may be applied two or more times. There is also no limit to the method for applying the glass paste; for example, it may be applied by stencil printing (e.g., screen printing).

In this embodiment, the thickness dimension (z-direction dimension) H2 of the heat storage layer 15 is, for example, 10 μm or more and 200 μm or less (preferably 15 μm or more and 60 μm or less). The ratio of the thickness dimension H2 to the width dimension (y-direction dimension) of the heat storage layer 15 (the so-called aspect ratio) is 0.05 or more and 0.25 or less. In this embodiment, the heat storage layer 15 is formed across the entire width of the top surface 131 in the y direction, so the width dimension of the heat storage layer 15 is the same as the width dimension (y-direction dimension) of the top surface 131, i.e., the y-direction dimension W2 of the upper end of the convex portion 12 in the z direction. The dimensions of the heat storage layer 15 are not limited. The thickness dimension H2 and width dimension W2 of the heat storage layer 15 are designed to enable sufficient heat storage while preventing unnecessary excessive heat storage. The number of times and method of glass paste application are determined depending on the required thickness (or aspect ratio) of the heat storage layer 15.

As shown in FIG. 6 , the heat storage layer 15 has a pair of rounded portions 151 formed on its upper surface at both ends in the y direction. Each of the pair of rounded portions 151 is a curved portion that rises upward. The pair of rounded portions 151 smoothly connects the surface of the heat storage layer 15 to each of the third inclined surfaces 143 of the pair of inclined portions 14 (convex portions 12). Each rounded portion 151 is formed by firing a glass paste when forming the heat storage layer 15. In the example shown in FIG. 6 , the upper surface of the heat storage layer 15 has a shape in which a substantially flat surface is interposed between the pair of rounded portions 151 in the y direction. However, the upper surface of the heat storage layer 15 may not have this substantially flat surface, and the pair of rounded portions 151 may be connected to each other. In this case, the upper surface of the heat storage layer 15 has a convex surface that curves upward in the z direction.

As shown in FIGS. 5 and 6 , the insulating layer 19 is formed on the main surface 11 of the substrate 10 and covers the substrate 10 and the heat storage layer 15. The insulating layer 19 contacts the main surface 11, each pair of first inclined surfaces 141, second inclined surfaces 142, and third inclined surfaces 143 of the protrusions 12, and the upper surface of the heat storage layer 15. The insulating layer 19 is intended to more reliably insulate the substrate 10 from the resistor layer 4 and the electrode layer 3. The insulating layer 19 may be formed in the region of the substrate 10 where the resistor layer 4 or the electrode layer 3 is to be formed. The insulating layer 19 is made of an insulating material, such as SiO ₂ or SiN (silicon nitride). The insulating layer 19 made of SiO ₂ can be formed by, for example, deposition using TEOS (tetraethyl orthosilicate; also known as tetraethoxysilane) as a source gas. The thickness of insulating layer 19 is not particularly limited, and is, for example, not less than 1 μm and not more than 10 μm.

As shown in Figures 5 and 6, the resistor layer 4 is formed on and covers the insulating layer 19. 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). There are no particular limitations on the thickness of the resistor layer 4, and it is, for example, 0.02 μm or more and 0.1 μm or less (preferably about 0.08 μm).

As shown in Figures 3, 5, and 6, the resistor layer 4 includes a plurality of heat generating portions 41. The heat generating portions 41 are exposed portions of the resistor layer 4 that are not covered by the electrode layer 3 described below. The heat generating portions 41 are selectively energized to locally heat the print medium. The 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 heat generating portions 41 in the y direction is an area that includes part or all of the apex 13 (top surface 131) of the convex portion 12 in the y direction. Therefore, each heat generating portion 41 overlaps the heat storage layer 15 when viewed in the z direction.

The electrode layer 3 forms a conductive path for supplying electricity to the multiple heat generating elements 41. The electrode layer 3 is laminated on the resistor layer 4 and supported by the substrate 10. The electrode layer 3 is made of a metal material with a lower resistance value than the resistor layer 4, such as 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 also be configured with a Cu layer and a Ti (titanium) layer laminated together. In this case, the Ti layer is interposed between the Cu layer and the resistor layer 4 and has a thickness of, for example, approximately 150 nm.

As shown in Figures 1 to 3, 5, and 6, the electrode layer 3 includes a plurality of individual electrodes 31 and a common electrode 32. The portions of the resistor layer 4 that are exposed from the electrode layer 3 between the plurality of individual electrodes 31 and the common electrode 32 form a plurality of heat generating portions 41.

Each of the multiple individual electrodes 31 is strip-shaped and extends generally in the y direction. Each individual electrode 31 is positioned upstream of each heat generating portion 41 in the y direction. As shown in Figures 3 and 6, in this embodiment, the downstream end of each individual electrode 31 in the y direction extends to the inclined portion 14 on the upstream side in the y direction. An electrode pad portion 311 is formed on the upstream end of each individual electrode 31 in the y direction. The electrode pad portion 311 is connected to the driver IC 7 mounted on the connection board 5 by a wire 61.

As shown in Figures 2 and 3, the common electrode 32 includes a common portion 323 and multiple comb tooth portions 324. The common portion 323 connects the multiple comb tooth portions 324 together. The common portion 323 extends in the x direction. The common portion 323 is located downstream in the y direction from the multiple comb tooth portions 324. Each comb tooth portion 324 is strip-shaped extending in the y direction from the upstream edge of the common portion 323. The multiple comb tooth portions 324 are spaced apart from each other and aligned in the x direction. The upstream tip of each comb tooth portion 324 in the y direction faces the tip of each individual electrode 31 at a predetermined distance. Therefore, the resistor layer 4 is exposed from the electrode layer 3 between the upstream tip of each comb tooth portion 324 in the y direction and the downstream tip of each individual electrode 31 in the y direction. As shown in Figures 3 and 6, the upstream tip of each comb tooth portion 324 in the y direction extends to the inclined portion 14 downstream in the y direction. The downstream portion of each comb tooth portion 324 in the y direction and the common portion 323 are formed on the main surface 11, as shown in Figure 2.

Note that the shapes of each individual electrode 31 and common electrode 32 as viewed in the z direction, and the formation areas of each individual electrode 31 and common electrode 32, are not limited to those described above. For example, the common electrode 32 may also be arranged upstream of each heat generating portion 41 in the y direction. In this case, the common portion 323 is arranged upstream of the multiple comb tooth portions 324 in the y direction, and the multiple comb tooth portions 324 are each arranged between each individual electrode 31. Furthermore, folded wiring for connecting the comb tooth portions 324 and the individual electrodes 31 is arranged downstream of each heat generating portion 41 in the y direction.

5 and 6, protective layer 2 covers electrode layer 3 and resistor layer 4. Protective layer 2 is made of an insulating material, such as _SiO2 , SiN, SiC (silicon carbide), or AlN (aluminum nitride), or a laminate of two or more of these. The thickness of protective layer 2 is not particularly limited, and is, for example, 1.0 μm to 10 μm.

As shown in Figure 5, the protective layer 2 has pad openings 21 that penetrate in the z direction. The pad openings 21 expose the electrode pad portions 311 provided on each of the multiple individual electrodes 31.

As shown in Figures 1 and 4, the connection board 5 is disposed adjacent to the head board 1 on the upstream side in the y direction. The connection board 5 is, for example, a PCB board. As shown in Figure 1, the connection board 5 has, for example, an elongated rectangular shape with the x direction as the longitudinal direction when viewed in the z direction. As shown in Figure 4, the connection board 5 is equipped with a driver IC 7 and a connector 59.

The connector 59 is used to connect the thermal printhead A1 to a printer (not shown). As shown in Figure 4, the connector 59 is attached to the connection board 5 and connected to the wiring pattern (not shown) of the connection board 5.

As shown in Figures 1 and 4, the driver IC 7 is mounted on the connection board 5 and individually energizes the multiple heat generating elements 41. As shown in Figures 4 and 5, the driver IC 7 is connected to each electrode pad 311 of each individual electrode 31 by multiple wires 61. The driver IC 7 is also connected to the wiring pattern formed on the connection board 5 by multiple wires 62. Print signals, control signals, and voltages supplied to the multiple heat generating elements 41 transmitted from the outside are input to the driver IC 7 via the connector 59. The multiple heat generating elements 41 are individually energized in accordance with the print signals and control signals, thereby selectively generating heat.

As shown in Figures 4 and 5, the driver IC 7 and multiple wires 61, 62 are covered with protective resin 78 formed to straddle the head substrate 1 and connection substrate 5. The protective resin 78 is made of a black insulating material such as epoxy resin.

As shown in FIG. 4, the heat dissipation member 8 supports the head substrate 1 and the connection substrate 5, and is provided to dissipate some of the heat generated by the multiple heat generating elements 41 to the outside. The heat dissipation member 8 is made of a metal such as aluminum.

Next, an example of a method for manufacturing the thermal printhead A1 will be described below with reference to Figures 7 to 15. Figure 7 is a flowchart showing an example of a method for manufacturing the thermal printhead A1. Figures 8 to 15 are cross-sectional views showing one step of an example of a method for manufacturing the thermal printhead A1, and correspond to the cross section shown in Figure 6. Note that the x, y, and z directions shown in Figures 8 to 15 are the same directions as in Figures 1 to 6.

As shown in Figure 7, the manufacturing method for the thermal printhead A1 includes a substrate preparation process S10, a first etching process S20, a heat storage layer formation process S30, a second etching process S40, a re-firing process S50, an insulating layer formation process S60, a heat generating portion formation process S70, a protective layer formation process S80, and a cutting process S90.

The substrate preparation step S10 is a step of preparing the substrate 10A, which will be the material. In this step, the substrate 10A is prepared as shown in Figure 8. The substrate 10A is made of a single-crystal semiconductor, such as a Si wafer. The substrate 10A has a principal surface 11A. The principal surface 11A is substantially flat and faces upward in the z direction. The principal surface 11A is a (100) plane.

The first etching step S20 is a step of performing a first etching process on the substrate 10A, forming the protrusions 12A as shown in FIG. 9. In this step, a predetermined mask layer 91 (shown by two-dot chain lines in FIGS. 8 and 9) is first formed on a portion of the main surface 11A of the substrate 10A. The mask layer 91 extends in the x direction and has two slits 92. The two slits 92 extend parallel to each other in the x direction and penetrate the mask layer 91 in the z direction. Anisotropic etching is then performed using, for example, an alkaline aqueous solution. Examples of alkaline aqueous solutions include KOH (potassium hydroxide) and TMAH (tetramethylammonium hydroxide). As a result, the substrate 10 is formed, having the main surface 11 and the protrusions 12A as shown in FIG. 9. The main surface 11 is a (100) plane, just like the main surface 11A.

The protrusion 12A protrudes from the principal surface 11 in the z direction and extends in the x direction. The protrusion 12A includes a top 13A and a pair of inclined portions 14A. The top 13A has a top surface 131A parallel to the principal surface 11. When viewed in the z direction, the top surface 131A has an elongated rectangular shape extending long in the x direction. The top surface 131A is a (100) plane. The top surface 131A is a portion of the principal surface 11A that is covered by the mask layer 91 and remains unetched. The top 13A also has two grooves 132A at positions corresponding to the two slits 92 in the mask layer 91. Each groove 132A is recessed from the top surface 131A in the z direction, extends in the x direction, and is V-shaped when viewed in the x direction. Each pair of side surfaces constituting the groove 132A is a (111) plane and is inclined with respect to the principal surface 11 and the top surface 131A. The third inclination angle α3 of each side surface is, for example, 54.8 degrees. The pair of inclined portions 14A are arranged on either side of the top portion 13A in the y direction. Each of the pair of inclined portions 14A has an inclined surface 141A. Each of the pair of inclined surfaces 141A is a (111) plane and is inclined with respect to the main surface 11 and the top surface 131A. The first inclination angle α1 of each inclined surface 141A is, for example, 54.8 degrees. The mask layer 91 is then removed.

As shown in FIG. 10, the heat storage layer forming process S30 is a process for forming the heat storage layer 15. In this process, glass paste is first applied to the area between the two grooves 132A on the top surface 131A of the convex portion 12A. In this embodiment, the glass paste is applied using, for example, a dispenser. The applied glass paste is fluid, but surface tension prevents it from crossing the boundary between the top surface 131A and the groove 132A. In this embodiment, the third inclination angle α3 of the side surface of the groove 132A is relatively large, which enhances this effect. In this embodiment, after applying the glass paste, another glass paste is applied on top of it. In other words, in this embodiment, glass paste is applied twice. Note that the number of times glass paste is applied is not limited. When applying glass paste two or more times, the applied glass paste may be dried in a drying process to make it easier to maintain its shape before applying the next glass paste. The method for applying the glass paste is also not limited; for example, it may be applied by stencil printing (e.g., screen printing).

The glass paste is then fired to form the heat storage layer 15, as shown in Figure 10. The heat generated during firing causes the glass paste to become fluid, but surface tension prevents it from crossing the boundary line between the top surface 131A and the groove 132A. In this embodiment, the third inclination angle α3 of the side surface of the groove 132A is relatively large, which enhances this effect. The glass paste is adjusted so that the thermal expansion coefficient of the fired heat storage layer 15 is similar to that of Si, the material of the substrate 10. The composition of the glass paste is not limited. Even when glass paste is applied multiple times, by using glass paste of the same composition, the fired heat storage layer 15 will be integrated and have no boundaries. When applying glass paste multiple times, firing may be performed each time a glass paste is applied.

The second etching step S40 is a second etching process, which removes a portion of the protrusion 12A, as shown in FIG. 11. In this process, a second anisotropic etching is performed again using an alkaline aqueous solution. The alkaline aqueous solution used is KOH or TMAH. In the second etching step S40, the heat storage layer 15 functions as a mask layer, eliminating the need to form a separate mask layer. The second anisotropic etching removes the portions of each inclined portion 14A and the top portion 13A indicated by the two-dot chain lines, as shown in FIG. 11. This results in the formation of the second inclined surface 142. The second inclination angle α2 of the second inclined surface 142 is, for example, 31°. The portion of the inclined surface 141A that is not removed by etching becomes the first inclined surface 141. Furthermore, the region of the top surface 131A between the two grooves 132A remains and becomes the top surface 131. Furthermore, one side of each groove 132A (the side closer to the heat storage layer 15) remains and connects to the top surface 131, forming a third inclined surface 143 that is inclined at a third inclination angle α3 with respect to the main surface 11.

The re-firing step S50 is a step in which the thermal storage layer 15 is re-fired. In the second etching step S40, fine irregularities may be formed on the surface of the thermal storage layer 15. In the re-firing step S50, the thermal storage layer 15 is melted and then solidified by re-firing. This results in a smooth surface on the surface of the thermal storage layer 15. Note that the re-firing step S50 may be omitted.

As shown in FIG. 12, the insulating layer formation process S60 is a process for forming an insulating layer 19 that covers the heat storage layer 15 and the substrate 10. In this process, film formation is performed using, for example, CVD, with TEOS as the source gas. The insulating layer 19 covers the main surface 11, the pair of inclined portions 14 (first inclined surface 141, second inclined surface 142, third inclined surface 143) of the convex portion 12, and the heat storage layer 15. Note that the method for forming the insulating layer 19 is not limited.

The heating element formation process S70 is a process of forming the heating elements 41 and the electrode layer 3 for conducting current to the heating elements 41 on the insulating layer 19. First, as shown in FIG. 13, a resistor film 4A is formed (S71). The resistor film 4A is formed by, for example, forming a thin film of TaN on the insulating layer 19 by sputtering. The resistor film 4A covers the entire surface of the insulating layer 19. Next, as shown in FIG. 14, a conductive film 3A is formed (S72). The conductive film 3A is formed by, for example, forming a layer made of Cu by plating or sputtering. The conductive film 3A covers the entire surface of the resistor film 4A. Note that the conductive film 3A may be formed by forming a Ti layer on the insulating layer 19 followed by a Cu layer. Next, as shown in FIG. 15, the conductive film 3A and the resistor film 4A are selectively etched to partially remove the conductive film 3A and the resistor film 4A (S73). This forms a resistor layer 4 separated in the x direction, and multiple individual electrodes 31 and common electrodes 32 that cover the resistor layer 4, leaving multiple heat generating portions 41.

The protective layer formation process S80 is a process for forming the protective layer 2. This process is performed by depositing, for example, SiN on each of the insulating layer 19, the electrode layer 3, and the resistor layer 4, using, for example, CVD. Thereafter, the protective layer 2 is partially removed by etching or the like to form the pad opening 21.

The cutting process S90 is a process for cutting the substrate 10. In this process, the substrate 10 is cut along the x and y directions to separate it into individual pieces. This results in the head substrate 1. The thermal printhead A1 shown in Figures 1 to 6 is then manufactured by assembling the head substrate 1 and connection board 5 onto the heat dissipation member 8, mounting the driver IC 7 on the connection board 5, bonding multiple wires 61 and 62, and forming the protective resin 78.

The above-described manufacturing method is an example and is not limited to this. For example, the second etching step S40 may be performed before the heat storage layer forming step S30. Hereinafter, the above-described manufacturing method will be referred to as the "first manufacturing method," and the manufacturing method in which the second etching step S40 is performed before the heat storage layer forming step S30 will be referred to as the "second manufacturing method." The second manufacturing method is a manufacturing method in which the heat storage layer forming step S30 and the second etching step S40 are swapped in the first manufacturing method. The substrate preparation step S10 and first etching step S20 are common to the first manufacturing method.

In the second manufacturing method, the second etching step S40 is performed after the first etching step S20. In the second etching step S40, before performing the etching process, a mask layer 93 is formed to cover the area between the two grooves 132A on the top surface 131A of the convex portion 12A, as shown in FIG. 16. Then, a second anisotropic etching is performed, removing the portions of each inclined portion 14A and the top portion 13A indicated by the two-dot chain lines, as shown in FIG. 17. This forms the first inclined surface 141, the second inclined surface 142, and the third inclined surface 143. Furthermore, the area of the top surface 131A covered by the mask layer 93 remains as the top surface 131. The mask layer 93 is then removed. Next, in the heat storage layer formation step S30, a glass paste is applied to the top surface 131 and fired to form the heat storage layer 15. Although the applied glass paste and the heated glass paste during firing are fluid, surface tension prevents them from crossing the boundary line between the top surface 131A and the third inclined surface 143. In the second manufacturing method, the second etching step S40 is performed before the heat storage layer 15 is formed, so the re-firing step S50 can be omitted. The subsequent insulating layer forming step S60, heating portion forming step S70, protective layer forming step S80, and cutting step S90 are the same as in the first manufacturing method.

Next, we will explain the operation of thermal printhead A1.

In this embodiment, the thermal printhead A1 has an inclined portion 14 that includes a first inclined surface 141 and a second inclined surface 142. The second inclined surface 142 is positioned between the first inclined surface 141 and the top surface 131 in the y direction. The second inclined surface 142 has a second inclined angle α2 that is smaller than the first inclined angle α1 of the first inclined surface 141. Therefore, compared to when the inclined portion 14 does not include the second inclined surface 142, the print medium transported by the platen roller 99 is less likely to get caught on the convex portions 12. The inclined portion 14 also includes a third inclined surface 143 that is positioned between the second inclined surface 142 and the top surface 131 in the y direction. However, the dimension of the third inclined surface 143 in the direction perpendicular to the x direction is sufficiently small that it has little effect on the print medium getting caught on the convex portions 12.

Furthermore, in this embodiment, the third inclination angle α3 of the third inclined surface 143 that connects to the top surface 131 in the y direction is greater than the second inclination angle α2 of the second inclined surface 142. Therefore, compared to when the second inclined surface 142 connects to the top surface 131, the glass paste placed on the top surface 131 can be more effectively prevented from flowing out of the top surface 131 when the glass paste is placed in the manufacturing process and when it is heated during firing.

Furthermore, according to this embodiment, the thermal printhead A1 includes a heat storage layer 15 formed between the substrate 10 and the resistor layer 4. When viewed in the z direction, each heat generating portion 41 of the resistor layer 4 overlaps the heat storage layer 15. Therefore, heat generated by each heat generating portion 41 is stored in the heat storage layer 15. The heat storage layer 15 is formed by depositing and firing a glass paste. Therefore, compared to, for example, a case in which _SiO2 is deposited as a heat storage layer by sputtering, the heat storage layer 15 can be formed with an overwhelmingly greater thickness in an overwhelmingly shorter time. This contributes greatly to improving the manufacturing efficiency and reducing costs of the thermal printhead A1.

Furthermore, according to this embodiment, the heat storage layer 15 is formed by applying glass paste twice. Therefore, a thicker heat storage layer 15 can be formed compared to when glass paste is applied only once.

Furthermore, according to this embodiment, the ratio of the z-direction dimension H2 to the width (y-direction dimension W2) of the heat storage layer 15 is 0.05 or more and 0.2 or less. Therefore, the heat storage layer 15 can appropriately store the heat generated by each heat generating portion 41.

In addition, according to this embodiment, the substrate 10 has protrusions 12, and multiple heat generating portions 41 are formed on the tops 13 (top surfaces 131) of the protrusions 12. This ensures that the print medium is pressed against the heat generating portions 41 via the platen roller 99. Furthermore, because the protrusions 12 are formed by anisotropic etching of a single-crystal semiconductor, their y-z cross sections are uniform in the x direction. In other words, the pressing contact state of the print medium against the heat generating portions 41 is consistent at each point in the x direction. This remains unchanged even if the production lot of the head substrate 1 is different, thereby reducing variations in print quality.

Figures 18 to 23 show other embodiments of the present disclosure. In these figures, elements that are the same as or similar to those in the above embodiment are designated by the same reference numerals as in the above embodiment.

Second Embodiment
18 is an enlarged cross-sectional view of a thermal printhead A2 according to a second embodiment of the present disclosure, corresponding to FIG. 6. The thermal printhead A2 of this embodiment differs from the above-described embodiment in that a parallel surface 144 is formed between a second inclined surface 142 and a third inclined surface 143. The configuration and operation of other parts of this embodiment are the same as those of the first embodiment. Note that the various parts of the first embodiment described above may be combined in any desired manner.

Each inclined portion 14 of the substrate 10 according to this embodiment further includes a parallel surface 144. The parallel surface 144 is disposed between the second inclined surface 142 and the third inclined surface 143 in the y direction and is connected to the second inclined surface 142 and the third inclined surface 143. The parallel surface 144 is parallel to the main surface 11.

In this embodiment, the inclined portion 14 also has a second inclined surface 142 located between the first inclined surface 141 and the top surface 131, which prevents the print medium from getting caught on the convex portion 12. Furthermore, the inclined portion 14 also has a third inclined surface 143 that connects to the top surface 131 in the y direction, which further prevents the glass paste from flowing out from the top surface 131 during the manufacturing process. Furthermore, the thermal printhead A2 has a common configuration with the thermal printhead A1, and therefore achieves the same effects as the thermal printhead A1.

Third Embodiment
19 is an enlarged cross-sectional view of a main portion of a thermal printhead A3 according to a third embodiment of the present disclosure, and corresponds to FIG. 6. The thermal printhead A3 of this embodiment differs from the above-described embodiments in that a fourth inclined surface 145 is formed between a second inclined surface 142 and a third inclined surface 143. The configuration and operation of other parts of this embodiment are the same as those of the first embodiment. Note that the parts of the first and second embodiments may be combined in any desired manner.

Each inclined portion 14 of the substrate 10 according to this embodiment further includes a fourth inclined surface 145. The fourth inclined surface 145 is disposed between the second inclined surface 142 and the third inclined surface 143 in the y direction and is connected to the second inclined surface 142 and the third inclined surface 143. The fourth inclined surface 145 is inclined at a third inclination angle α3 with respect to the main surface 11 and is inclined in the opposite direction from the third inclined surface 143 in the y direction. In other words, the third inclined surface 143 and the fourth inclined surface 145 form a V-shape when viewed in the x direction. The fourth inclined surface 145 is the portion of the other side surface (the side surface away from the heat storage layer 15) of the groove 132A shown in FIG. 10 that remains unremoved by the second etching step S40.

In this embodiment, the inclined portion 14 also has a second inclined surface 142 located between the first inclined surface 141 and the top surface 131, which prevents the print medium from getting caught on the convex portion 12. Furthermore, the inclined portion 14 also has a third inclined surface 143 that connects to the top surface 131 in the y direction, which further prevents the glass paste from flowing out from the top surface 131 during the manufacturing process. Furthermore, the thermal printhead A3 has a common configuration with the thermal printhead A1, and therefore achieves the same effects as the thermal printhead A1.

The first to third embodiments each have a different shape for the convex portion 12. These differences arise from the position in the y direction and depth (dimension in the z direction) of the pair of grooves 132A formed in the first etching step S20, the etching processing time in the second etching step S40, and other factors. Conversely, by adjusting these parameters, the shape of the convex portion 12 can be adjusted to the desired shape.

Fourth Embodiment
20 is an enlarged cross-sectional view of a main portion of a thermal printhead A4 according to a fourth embodiment of the present disclosure, and corresponds to FIG. 6. The thermal printhead A4 of this embodiment differs from the above-described embodiments in that the insulating layer 19 does not cover the heat storage layer 15. The configuration and operation of other parts of this embodiment are the same as those of the first embodiment. Note that the parts of the first to third embodiments may be combined in any desired manner.

The insulating layer 19 according to this embodiment covers only the main surface 11 and the pair of inclined portions 14 (first inclined surface 141, second inclined surface 142, third inclined surface 143) of the convex portion 12, and does not cover the heat storage layer 15. Such an insulating layer 19 is formed in the insulating layer forming step S60 by, for example, thermal oxidation treatment in which the substrate 10 is thermally oxidized to form a _SiO2 film, rather than by laminating _SiO2 using CVD. In this embodiment, although the insulating layer 19 does not cover the heat storage layer 15, the heat storage layer 15 itself is an insulator, and therefore the substrate 10 can be insulated from the resistor layer 4 and the electrode layer 3.

In this embodiment, the inclined portion 14 also has a second inclined surface 142 located between the first inclined surface 141 and the top surface 131, which prevents the print medium from getting caught on the convex portion 12. Furthermore, the inclined portion 14 also has a third inclined surface 143 that connects to the top surface 131 in the y direction, which further prevents the glass paste from flowing out from the top surface 131 during the manufacturing process. Furthermore, the thermal printhead A4 has a common configuration with the thermal printhead A1, and therefore achieves the same effects as the thermal printhead A1.

Furthermore, in this embodiment, the insulating layer 19 can be formed of a _SiO2 film obtained by thermally oxidizing the substrate 10. Therefore, the manufacturing process can be simplified compared to when _SiO2 is deposited using CVD in the insulating layer forming step S60. Note that when the thermal printhead A4 is manufactured by the second manufacturing method, the insulating layer 19 may be formed between the heat storage layer 15 and the top surface 131.

Fifth Embodiment
21 to 23 are diagrams illustrating a thermal printhead A5 according to a fifth embodiment of the present disclosure. FIG. 21 is an enlarged cross-sectional view of a main portion of the thermal printhead A5, corresponding to FIG. 6. FIGS. 22 and 23 are cross-sectional views illustrating a step in an exemplary method for manufacturing the thermal printhead A5, corresponding to the cross section shown in FIG. 21. The thermal printhead A5 of this embodiment differs from the above-described embodiments in that the third inclined surface 143 is a surface that is substantially perpendicular to the main surface 11. The configuration and operation of other parts of this embodiment are similar to those of the first embodiment. Note that the parts of the first to fourth embodiments may be combined in any desired manner.

As shown in Figure 21, in the convex portion 12 of the substrate 10 according to this embodiment, the third inclined surface 143 is a surface that is approximately perpendicular to the main surface 11. In other words, the third inclination angle α3 is approximately a right angle. The manufacturing method for thermal printhead A5 differs from the manufacturing method for thermal printhead A1 in the method for forming the groove 132A.

In the manufacturing method of thermal printhead A5, as shown in FIG. 22, the mask layer 91 formed on the main surface 11A in the first etching step S20 does not have slits 92. Therefore, grooves 132A are not formed in the first etching step S20. Then, as shown in FIG. 23, two grooves 132A are formed in the top surface 131A. The method for forming the grooves 132A is not limited; for example, they may be formed using a laser, or they may be formed using a dicing blade to create a so-called half-cut state. Subsequent processes are the same as those in the manufacturing method of thermal printhead A1.

In this embodiment, the inclined portion 14 also has a second inclined surface 142 located between the first inclined surface 141 and the top surface 131, which prevents the print medium from getting caught on the convex portion 12. Furthermore, the inclined portion 14 also has a third inclined surface 143 that connects to the top surface 131 in the y direction, which further prevents the glass paste from flowing out from the top surface 131 during the manufacturing process. Furthermore, the thermal printhead A5 has a common configuration with the thermal printhead A1, and therefore achieves the same effects as the thermal printhead A1.

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

[Appendix 1]
A substrate (10) having a main surface (11) facing one side in the thickness direction (z direction) and made of a single crystal semiconductor;
a resistor layer (4) formed on the main surface and including a plurality of heat generating portions (41) arranged in the main scanning direction (x direction);
an insulating layer (19) formed between the substrate and the resistor layer;
a heat storage layer (15) formed between the substrate and the plurality of heat generating portions and being a glaze made of a glass material;
Equipped with
The substrate has a protrusion (12) that protrudes from the main surface and extends in the main scanning direction,
The convex portion is
a top portion (13) having a top surface (131) parallel to the main surface;
an inclined portion (14) connected to the top portion and the main surface and inclined relative to the main surface;
Equipped with
The inclined portion is
a first inclined surface (141) connected to the main surface and inclined at a first inclination angle relative to the main surface;
a second inclined surface (142) interposed between the first inclined surface and the top surface and inclined at a second inclination angle with respect to the main surface;
Equipped with
The heat storage layer is formed only on the top surface.
Thermal print head.
[Appendix 2]
The first tilt angle is greater than the second tilt angle.
2. The thermal printhead of claim 1.
[Appendix 3]
The inclined portion further includes a third inclined surface (143) connected to the top surface and inclined at a third inclination angle with respect to the main surface.
3. The thermal printhead according to claim 1 or 2.
[Appendix 4]
the first tilt angle and the third tilt angle are equal;
4. The thermal printhead of claim 3.
[Appendix 5]
the second inclined surface and the third inclined surface are connected to each other;
5. The thermal printhead according to claim 3 or 4.
[Appendix 6, Second embodiment, FIG. 18]
The inclined portion further includes a parallel surface (144) that is connected to the second inclined surface and the third inclined surface and is parallel to the main surface.
5. The thermal printhead according to claim 3 or 4.
[Appendix 7, Figure 6]
The dimension (W1) of the convex portion in the sub-scanning direction is between two and ten times the dimension (W2) of the top portion in the sub-scanning direction.
7. A thermal printhead according to any one of claims 1 to 6.
[Appendix 8]
the single-crystal semiconductor is made of Si,
The main surface is a (100) surface.
8. A thermal printhead according to any one of claims 1 to 7.
[Appendix 9, Figure 6]
a ratio of the thickness direction dimension (H2) of the heat storage layer to the sub-scanning direction dimension (W2) is 0.05 or more and 0.25 or less;
9. A thermal printhead according to any one of claims 1 to 8.
[Appendix 10]
The dimension of the heat storage layer in the thickness direction is 15 μm or more and 60 μm or less.
10. A thermal printhead according to any one of claims 1 to 9.
[Appendix 11]
the heat storage layer is formed over the entire width of the top surface in the sub-scanning direction;
11. A thermal printhead according to any one of claims 1 to 10.
[Appendix 12, Figure 7]
A preparation step (S10) of preparing a substrate made of a single crystal semiconductor;
a first etching step (S20) of performing a first anisotropic etching on the base material to form a main surface facing one side in the thickness direction, a convex portion protruding from the main surface, and two grooves recessed from a top surface of the convex portion parallel to the main surface and extending in the main scanning direction;
a heat storage layer forming step (S30) of forming a heat storage layer by disposing and firing glass paste in the area between the two grooves on the top surface;
a second etching step (S40) of performing a second anisotropic etching on the base material to remove a portion of the convex portion, thereby forming, in the convex portion, a top surface that is a region of the top surface sandwiched between the two grooves, a first inclined surface that is connected to the main surface and inclined at a first inclination angle with respect to the main surface, and a second inclined surface that is interposed between the first inclined surface and the top surface and inclined at a second inclination angle with respect to the main surface;
a heat generating portion forming step (S70) of forming a plurality of heat generating portions arranged in the main scanning direction on the heat storage layer;
Equipped with
A method for manufacturing a thermal printhead.
[Appendix 12-1]
a preparation step of preparing a substrate made of a single crystal semiconductor;
a first etching step of performing a first anisotropic etching on the base material to form a main surface facing one side in a thickness direction, a convex portion protruding from the main surface, and two grooves recessed from a top surface of the convex portion parallel to the main surface and extending in a main scanning direction;
a second etching step of performing a second anisotropic etching on the base material to remove a portion of the convex portion, thereby forming, in the convex portion, a top surface which is a region of the top surface sandwiched between the two grooves, a first inclined surface which is connected to the main surface and is inclined at a first inclination angle (55°) with respect to the main surface, and a second inclined surface which is interposed between the first inclined surface and the top surface and is inclined at a second inclination angle (31°) with respect to the main surface;
a heat storage layer forming step of forming a heat storage layer by disposing a glass paste on the top surface and firing it;
a heat generating portion forming step of forming a plurality of heat generating portions arranged in the main scanning direction on the heat storage layer;
Equipped with
A method for manufacturing a thermal printhead.
[Appendix 13]
In the second etching step, a third inclined surface is further formed in the convex portion, the third inclined surface being connected to the top surface and inclined at the first inclination angle with respect to the main surface.
13. A method for manufacturing a thermal printhead according to claim 12.
[Appendix 14]
The method further includes an insulating layer forming step (S60) that is performed between the second etching step and the heat generating portion forming step and that forms an insulating layer that covers the heat storage layer and the base material.
14. A method for manufacturing a thermal printhead according to claim 12 or 13.
[Appendix 15]
The method further includes a re-firing step (S50) performed between the second etching step and the insulating layer forming step, in which the heat storage layer is melted by firing and then solidified.
15. A method for manufacturing a thermal printhead according to claim 14.

A1 to A5: thermal print head 1: head substrate 10: substrate 11: main surface 12: convex portion 13: apex portion 131: apex surface 14: inclined portion 141: first inclined surface 142: second inclined surface 143: third inclined surface 144: parallel surface 145: fourth inclined surface 15: heat storage layer 151: rounded portion 19: insulating layer 2: protective layer 21: pad opening 3: electrode layer 31: individual electrode 311: electrode pad portion 32: common electrode 323: common portion 324: comb-tooth portion 4: resistor layer 41: heat generating portion 5: connection substrate 59: connector 61: wire 62: wire 7: driver IC
78: Protective resin 8: Heat dissipation member 99: Platen roller 10A: Base material 11A: Main surface 12A: Convex portion 13A: Peak 131A: Top surface 132A: Groove 14A: Sloped portion 141A: Sloped surface 3A: Conductive film 4A: Resistor films 91, 93: Mask layer 92: Slit

Claims (13)

a substrate having a main surface facing in one direction in a thickness direction and made of a single crystal semiconductor;
a resistor layer formed on the main surface and including a plurality of heat generating portions arranged in a main scanning direction;
an insulating layer formed between the substrate and the resistor layer;
a heat storage layer formed between the base material and the plurality of heat generating portions and being a glaze made of a glass material;
Equipped with
the base material includes a protrusion protruding from the main surface and extending in the main scanning direction;
The convex portion is
a top portion having a top surface parallel to the main surface;
an inclined portion that is connected to the top portion and the main surface and is inclined with respect to the main surface;
Equipped with
The inclined portion is
a first inclined surface connected to the main surface and inclined at a first inclination angle with respect to the main surface;
a second inclined surface interposed between the first inclined surface and the top surface and inclined at a second inclination angle with respect to the main surface;
a third inclined surface connected to the top surface and inclined at a third inclination angle with respect to the main surface;
Equipped with
The heat storage layer is formed only on the top surface.
Thermal print head. The first tilt angle is greater than the second tilt angle.
2. The thermal printhead of claim 1. the first tilt angle and the third tilt angle are equal;
3. The thermal printhead according to claim 1 or 2 . the second inclined surface and the third inclined surface are connected to each other;
4. The thermal printhead according to claim 1 . the inclined portion further includes a parallel surface that is connected to the second inclined surface and the third inclined surface and is parallel to the main surface.
4. The thermal printhead according to claim 1 . the dimension of the convex portion in the sub-scanning direction is between two and ten times the dimension of the apex portion in the sub-scanning direction;
6. A thermal printhead according to claim 1. the single-crystal semiconductor is made of Si,
The main surface is a (100) surface.
7. The thermal printhead according to claim 1. a ratio of the thickness direction dimension of the heat storage layer to the sub-scanning direction dimension is 0.05 or more and 0.25 or less;
8. The thermal printhead according to claim 1. The dimension of the heat storage layer in the thickness direction is 15 μm or more and 60 μm or less.
9. A thermal printhead according to claim 1. the heat storage layer is formed over the entire width of the top surface in the sub-scanning direction;
10. The thermal printhead according to claim 1. a preparation step of preparing a substrate made of a single crystal semiconductor;
a first etching step of performing a first anisotropic etching on the base material to form a main surface facing one side in a thickness direction, a convex portion protruding from the main surface, and two grooves recessed from a top surface of the convex portion parallel to the main surface and extending in a main scanning direction;
a heat storage layer forming step of forming a heat storage layer by disposing a glass paste in the area between the two grooves on the top surface and firing the paste;
a second etching step of performing a second anisotropic etching on the base material to remove a portion of the convex portion, thereby forming, in the convex portion, a top surface which is a region of the top surface sandwiched between the two grooves, a first inclined surface which is connected to the main surface and is inclined at a first inclination angle with respect to the main surface, and a second inclined surface which is interposed between the first inclined surface and the top surface and is inclined at a second inclination angle with respect to the main surface;
a heat generating portion forming step of forming a plurality of heat generating portions arranged in the main scanning direction on the heat storage layer;
Equipped with
In the second etching step, a third inclined surface is further formed in the convex portion, the third inclined surface being connected to the top surface and inclined at the first inclination angle with respect to the main surface.
A method for manufacturing a thermal printhead. The method further includes an insulating layer forming step, which is performed between the second etching step and the heat generating portion forming step, and which forms an insulating layer that covers the heat storage layer and the base material.
The method for manufacturing the thermal printhead according to claim 11 . The method further includes a re-firing step, which is performed between the second etching step and the insulating layer forming step, in which the heat storage layer is melted by firing and then solidified.
The method for manufacturing a thermal printhead according to claim 12 .