JP7204964B2 - thermal print head - Google Patents

Description

The present disclosure relates to thermal printheads .

Patent Document 1 discloses an example of a conventional thermal printhead. The thermal printhead disclosed in the same document comprises a substrate, a glaze layer, an electrode layer, a resistor layer and a protective layer. The substrate is a plate-shaped member made of an insulating material. The glaze layer is formed on the surface of the substrate and is made of glass, for example. The electrode layer is formed on the glaze layer and constitutes a current path for selectively applying current to the resistor layer. The electrode layer has a common electrode and a plurality of individual electrodes. The common electrode and the individual electrodes are electrically opposite electrodes. A portion of the resistor layer sandwiched between a portion of the common electrode and the individual electrode in the main scanning direction serves as a heat generating portion. The protective layer is for protecting the electrode layer, and is made of glass, for example.

A voltage is applied to a predetermined portion of the thermal print head during use, and this generates heat. The potential difference, heat, etc. at this time can be a cause of deterioration of, for example, the electrode layer and the resistor layer.

JP-A-10-16268

The present disclosure has been conceived under the circumstances described above, and aims to provide a thermal printhead and a method for manufacturing a thermal printhead that can suppress deterioration of electrode layers and resistor layers. This is one of the tasks.

The present disclosure has been conceived under the circumstances described above, and one of the objects thereof is to provide a thermal printhead and a method for manufacturing the thermal printhead that enable high-definition printing.

A thermal printhead provided by the first aspect of the present disclosure is a thermal printhead comprising a substrate, an electrode layer, and a resistor layer including a plurality of heat generating portions arranged in a main scanning direction, The electrode layer includes a first layer interposed between the resistor layer and the substrate, and a second layer separated from the resistor layer and having a covering portion formed on the first layer. and the first metal contained in the first layer has a smaller degree of diffusion into the resistor layer than the second metal contained in the second layer.

A method of manufacturing a thermal printhead provided by the second aspect of the present disclosure includes forming a glaze layer on a substrate; forming a first metal film containing a first metal on the glaze layer; forming a first layer by patterning a first metal film; forming a second metal film covering at least a portion of the first layer and containing a second metal; and forming the second metal film. and forming a resistor layer covering part of the first layer and spaced apart from the second layer, wherein the first metal is the The degree of diffusion into the resistor layer is smaller than that of the second metal.

A thermal printhead provided by a third aspect of the present disclosure is a thermal printhead comprising a substrate, an electrode layer, and a resistor layer including a plurality of heat generating portions arranged in a main scanning direction, The electrode layer has a first layer interposed between the resistor layer and the substrate, and a second layer separated from the resistor layer and electrically connected to the first layer. a layer comprising a first metal and glass; said second layer comprising a lower layer comprising a second metal and glass and having an underlayer coating covering said first layer; an upper layer having an upper covering portion not in contact with one layer and covering said lower layer, said lower layer having a lower glass content than said upper layer.

A method for manufacturing a thermal printhead provided by the fourth aspect of the present disclosure includes the steps of forming a glaze layer on a substrate, forming a first metal film containing a first metal on the glaze layer, and forming a first layer by patterning a first metal film; forming a lower metal film containing a second metal covering at least a portion of the first layer; forming an upper metal film containing the second metal that partially covers and does not contact the first metal film; and forming a second layer by patterning the lower metal film and the upper metal film. and forming a resistor layer covering part of the first layer and spaced apart from the second layer, wherein the step of forming the lower layer metal film includes: and firing the resinate second metal paste, wherein the step of forming the upper layer metal film includes the second metal and the glass frit A step of applying a glass frit second metal paste by printing and a step of firing the glass frit second metal paste are included.

Other features and advantages of the present disclosure will become more apparent from the detailed description below with reference to the accompanying drawings.

1 is a plan view showing a thermal printhead according to a first embodiment of the present disclosure; FIG. FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1; 2 is an enlarged plan view of a main part showing the thermal print head of FIG. 1; FIG. 2 is an enlarged plan view of a main part showing the thermal print head of FIG. 1; FIG. FIG. 5 is an enlarged cross-sectional view of a main part taken along line VV of FIG. 4; FIG. 5 is an enlarged cross-sectional view of a main part taken along line VI-VI of FIG. 4; FIG. 5 is an enlarged cross-sectional view of a main part taken along line VII-VII of FIG. 4; 2 is an enlarged plan view of a main part showing the thermal print head of FIG. 1; FIG. FIG. 9 is a cross-sectional view of a main part taken along line IX-IX in FIG. 8; 2 is an enlarged plan view of a main part showing an example of a method of manufacturing the thermal print head of FIG. 1; FIG. 2 is an enlarged plan view of a main part showing an example of a method of manufacturing the thermal print head of FIG. 1; FIG. 2 is an enlarged plan view of a main part showing an example of a method of manufacturing the thermal print head of FIG. 1; FIG. FIG. 13 is an enlarged cross-sectional view of a main part taken along line XIII-XIII of FIG. 12; 2 is an enlarged cross-sectional view of a main part showing an example of a method of manufacturing the thermal print head of FIG. 1; FIG. 2 is an enlarged plan view of a main part showing an example of a method of manufacturing the thermal print head of FIG. 1; FIG. 2 is an enlarged cross-sectional view of a main part showing a modification of the thermal print head of FIG. 1; FIG. 2 is an enlarged cross-sectional view of a main part showing a modification of the thermal print head of FIG. 1; FIG. FIG. 2 is an enlarged plan view of a main portion showing an embodiment of the thermal print head of FIG. 1; FIG. 2 is an enlarged cross-sectional view of a main part showing an embodiment of the thermal print head of FIG. 1; FIG. 5 is an enlarged cross-sectional view of a main part showing a thermal printhead according to a second embodiment of the present disclosure; FIG. 10 is a plan view showing a thermal printhead according to a third embodiment of the present disclosure; FIG. 22 is a cross-sectional view along line XXII-XXII of FIG. 21; 22 is an enlarged plan view of a main part showing the thermal print head of FIG. 21; FIG. 22 is an enlarged plan view of a main part showing the thermal print head of FIG. 21; FIG. FIG. 25 is an enlarged cross-sectional view of a main part taken along line XXV-XXV of FIG. 24; 22 is an enlarged plan view of a main part showing the thermal print head of FIG. 21; FIG. FIG. 27 is a cross-sectional view of a main part taken along line XXVII-XXVII of FIG. 26; FIG. 22 is an enlarged plan view of a main part showing an example of a method of manufacturing the thermal print head of FIG. 21; FIG. 22 is an enlarged plan view of a main part showing an example of a method of manufacturing the thermal print head of FIG. 21; FIG. 22 is an enlarged plan view of a main part showing an example of a method of manufacturing the thermal print head of FIG. 21; FIG. 22 is an enlarged plan view of a main part showing an example of a method of manufacturing the thermal print head of FIG. 21; FIG. 32 is an enlarged cross-sectional view of a main part taken along line XXXII-XXXII of FIG. 31; FIG. 22 is an enlarged cross-sectional view of a main part showing an example of a method of manufacturing the thermal print head of FIG. 21; FIG. 34 is an enlarged cross-sectional view of a main part taken along line XXXIV-XXXIV of FIG. 33; FIG. 22 is an enlarged plan view of a main portion showing a specific example of the thermal print head of FIG. 21; FIG. 11 is an enlarged cross-sectional view of a main part showing a thermal print head according to a fourth embodiment of the present disclosure; FIG. 11 is an enlarged cross-sectional view of a main part showing a thermal printhead according to a fifth embodiment of the present disclosure;

Preferred embodiments of the present disclosure will be specifically described below with reference to the drawings.

1-9 show an example of a thermal printhead according to the present disclosure. The thermal printhead A1 of this embodiment includes a substrate 1, a glaze layer 2, an electrode layer 3, a resistor layer 4, a protective layer 55, a drive IC 71, a sealing resin 72, a connector 73, a wiring board 74 and a heat dissipation member 75. ing. The thermal print head A1 is incorporated in a printer for printing on thermal paper to create bar code sheets and receipts, for example. For convenience of understanding, the protective layer 55 is omitted in FIGS. 1, 3, 4 and 8. FIG. In these figures, the main scanning direction is the x direction, the sub-scanning direction is the y direction, and the thickness direction of the substrate 1 is the z direction.

FIG. 1 is a plan view showing the thermal print head A1. FIG. 2 is a cross-sectional view along line II-II of FIG. FIG. 3 is an enlarged plan view of the main part showing the thermal print head A1. FIG. 4 is an enlarged plan view of the main part showing the thermal print head A1. FIG. 5 is an enlarged cross-sectional view of a main part taken along line VV of FIG. FIG. 6 is an enlarged cross-sectional view of a main part taken along line VI--VI of FIG. FIG. 7 is an enlarged cross-sectional view of a main part taken along line VII--VII in FIG. FIG. 8 is an enlarged plan view of the main part showing the thermal print head A1. FIG. 9 is a cross-sectional view of the essential part along line IX-IX in FIG.

The substrate 1 is made of ceramic such as AlN or Al ₂ O ₃ and has a thickness of about 0.6 to 1.0 mm. As shown in FIG. 1, the substrate 1 has a long rectangular shape extending in the main scanning direction x. In addition to the substrate 1, the structure may have a wiring substrate 74 in which a substrate layer made of, for example, glass epoxy resin and a wiring layer made of Cu or the like are laminated. A heat radiating member 75 made of a metal such as Al is provided on the lower surface of the substrate 1 . In the configuration having the wiring substrate 74, for example, the substrate 1 and the wiring substrate 74 are arranged adjacently on the heat radiating member 75, and the wiring between the electrode layer 3 on the substrate 1 and the wiring substrate 74 (or the IC connected to this wiring). ) are connected, for example, by wire bonding. Furthermore, the wiring board 74 may be provided with the connector 73 shown in FIG.

Glaze layer 2 is formed on substrate 1 and is made of a glass material such as amorphous glass. The softening point of this glass material is, for example, 800-850.degree. The glaze layer 2 is formed by printing a thick film of glass paste and then firing it. In this embodiment, the entire upper surface of the substrate 1 in the figure is covered with the glaze layer 2 .

The electrode layer 3 constitutes a path for energizing the resistor layer 4, and is made of a conductive material. The electrode layer 3 has a first layer 3a and a second layer 3b. Furthermore, in this embodiment, as shown in FIGS. 8 and 9, the electrode layer 3 further has a third layer 3c.

The first layer 3a is formed on the glaze layer 2 and is made of, for example, resinate Au to which rhodium, vanadium, bismuth, silicon, or the like is added as additive elements. In this embodiment, the main component of the first layer 3a is Au, and Au corresponds to an example of the first metal. The first layer 3a is formed by printing a resinate Au paste as a thick film and then firing the same. The first layer 3a may be configured by laminating a plurality of Au layers. The thickness of first layer 3a is, for example, about 0.6 to 1.2 μm.

A part of the second layer 3 b is formed on the first layer 3 a and the other part is formed on the glaze layer 2 . Also, the second layer 3 b is separated from the resistor layer 4 . The second layer 3b is formed, for example, by printing and firing a paste containing an organic Ag compound or a paste containing Ag particles, glass frit, Pd, and resin. In this embodiment, the main component of the second layer 3b is Ag, and Ag corresponds to an example of the second metal. Au as the first metal has a smaller degree of diffusion into the resistor layer 4, which will be described later, than Ag as the second metal. Also, the second layer 3b may contain an additive element such as Pd. Also, the second layer 3b may contain glass. The thickness of second layer 3b is, for example, 2 μm to 10 μm.

The third layer 3c is laminated on the second layer 3b. In this embodiment, the third layer 3c has the same composition as the second layer 3b and contains Ag as a main component. Ag corresponds to an example of the third metal. The thickness of the third layer 3c is not particularly limited, and is the same as that of the second layer 3b in this embodiment.

As shown in FIG. 3 , the electrode layer 3 has a common electrode 33 and multiple individual electrodes 36 .

The common electrode 33 has a plurality of common electrode strip portions 34 and connecting portions 35 . The connecting portion 35 is disposed near the downstream end in the sub-scanning direction y of the substrate 1 and has a strip shape extending in the main scanning direction x. The plurality of common electrode strip portions 34 each extend in the sub-scanning direction y from the connecting portion 35 and are arranged at equal pitches in the main scanning direction x. Further, in the present embodiment, an Ag layer 351 is laminated on the connecting portion 35 . The Ag layer 351 is for reducing the resistance value of the connecting portion 35 .

The plurality of individual electrodes 36 is for partially energizing the resistor layer 4 and is a portion having a polarity opposite to that of the common electrode 33 . The individual electrode 36 extends from the resistor layer 4 toward the drive IC 71 . A plurality of individual electrodes 36 are arranged in the main scanning direction x, each having an individual electrode strip portion 38 , a connecting portion 37 and a bonding portion 39 .

Each individual electrode strip portion 38 is a strip portion extending in the sub-scanning direction y and positioned between two adjacent common electrode strip portions 34 of the common electrode 33 . The individual electrode strip portion 38 of the individual electrode 36 and the common electrode strip portion 34 of the common electrode 33 have a width of, for example, 25 μm or less. The distance from the belt-like portion 34 is, for example, 40 μm or less.

The connecting portion 37 is a portion extending from the individual electrode strip portion 38 toward the driving IC 71, and most of the connecting portion 37 has a portion along the sub-scanning direction y and a portion inclined with respect to the sub-scanning direction y. The width of most of the connecting portions 37 is, for example, 20 μm or less, and the distance between adjacent connecting portions 37 is, for example, 20 μm or less.

The bonding portion 39 is formed at the y end of the individual electrode 36 in the sub-scanning direction, and is bonded with a wire 61 for connecting the individual electrode 36 and the drive IC 71 . The bonding portions 39 of adjacent individual electrodes 36 are arranged alternately in the sub-scanning direction y. As a result, although the bonding portion 39 has a larger width than most portions of the connecting portion 37, the bonding portions 39 are prevented from interfering with each other.

A portion of the connecting portion 37 sandwiched between the adjacent bonding portions 39 has the smallest width in the individual electrode 36, and the width thereof is, for example, 10 μm or less. Also, the distance between the connecting portion 37 and the adjacent bonding portion 39 is, for example, 10 μm or less. Thus, the common electrode 33 and the plurality of individual electrodes 36 are fine patterns with small line widths and small line intervals.

As shown in FIGS. 4 and 5, the plurality of common electrode strip portions 34 of the common electrode 33 and the individual electrode strip portions 38 of the plurality of individual electrodes 36 are composed only of the first layer 3a. As shown in FIGS. 4, 5 and 6, the second layer 3b has a covering portion 31b and a sinking portion 32b. The covering portion 31b is a portion of the second layer 3b that covers the first layer 3a. The sedimentation portion 32 b is a portion of the second layer 3 b that is directly formed on the glaze layer 2 , and at least part of it is sedimented on the glaze layer 2 .

As shown in FIGS. 4, 5 and 7, in this embodiment, most of the connecting portions 37 of the plurality of individual electrodes 36 are composed only of the sedimentation portions 32b. In addition, in the present embodiment, the first layer 3a hardly settles with respect to the glaze layer 2. As shown in FIG. As a result, the covering portion 31 b does not settle with respect to the glaze layer 2 . As shown in FIGS. 4 and 5, the second layer 3b covers the edge 31a of the first layer 3a.

As shown in FIGS. 8 and 9, in this embodiment, the bonding portion 39 is composed of the second layer 3b and the third layer 3c. As shown in FIG. 9, the second layer 3b forming the bonding portion 39 is the sedimented portion 32b, at least a part of which is sedimented with respect to the glaze layer 2. As shown in FIG. On the other hand, the third layer 3c is formed on the second layer 3b, at least a portion of which is exposed from the glaze layer 2, and in this embodiment most of it sinks into the glaze layer 2. not

The resistor layer 4 is made of, for example, ruthenium oxide, which has a higher resistivity than the material forming the electrode layer 3, and is formed in a strip shape extending in the main scanning direction x. The resistor layer 4 intersects a plurality of common electrode strips 34 of the common electrode 33 and individual electrode strips 38 of a plurality of individual electrodes 36 . Furthermore, the resistor layer 4 is laminated on the side opposite to the substrate 1 with respect to the plurality of common electrode strip portions 34 of the common electrode 33 and the individual electrode strip portions 38 of the plurality of individual electrodes 36 . That is, the resistor layer 4 is in contact only with the first layer 3 a of the electrode layer 3 . A portion of the resistor layer 4 sandwiched between the common electrode strip portions 34 and the individual electrode strip portions 38 is a heat generating portion 41 that generates heat by being partially energized by the electrode layer 3 . Print dots are formed by the heat generated by the heating portion 41 . The thickness of resistor layer 4 is, for example, 4 μm to 6 μm.

The protective layer 55 is for protecting the electrode layer 3 and the resistor layer 4 . Protective layer 55 is made of, for example, amorphous glass. However, the protective layer 55 exposes regions including the bonding portions 39 of the plurality of individual electrodes 36 .

The drive IC 71 performs a function of partially heating the resistor layer 4 by selectively energizing the plurality of individual electrodes 36 . The driving IC 71 is provided with a plurality of pads. Pads of the drive IC 71 and the plurality of individual electrodes 36 are connected via a plurality of wires 61 bonded to each. The wire 61 is made of Au. As shown in FIGS. 1 and 2, the drive IC 71 and wires 61 are covered with a sealing resin 72. As shown in FIG. The sealing resin 72 is made of, for example, a black soft resin. Further, the driving IC 71 and the connector 73 are connected by a signal line (not shown).

Next, an example of a method for manufacturing the thermal print head A1 will be described below with reference to FIGS. 10 to 15. FIG.

First, as shown in FIG. 10, a substrate 1 made of AlN, for example, is prepared. Next, after a thick film of glass paste is printed on the substrate 1, the glaze layer 2 is formed by firing the paste. Next, after printing a resinate Au paste as a thick film, it is fired to form the first metal film 30a. In the illustrated example, the formation area of the first metal film 30a is a limited area in the sub-scanning direction y. The first metal film 30a has an edge 301a extending in the main scanning direction x.

Next, the first layer 3a shown in FIG. 11 is formed by subjecting the first metal film 30a to patterning using, for example, etching. The first layer 3a has portions that become a plurality of common electrode strip portions 34, a plurality of individual electrode strip portions 38, connecting portions 35, and the like. The first layer 3a also has an edge 31a. The edge 31a is a part where the edge 301a of the first metal film 30a remains. That is, the edge 31a is not formed by etching or the like for patterning the first metal film 30a.

Next, as shown in FIGS. 12 and 13, a second metal film 30b is formed. The formation of the second metal film 30b is carried out by printing a thick film of the Ag-containing paste described above on a predetermined region and then firing it. In the illustrated example, the second metal film 30b is formed to cover the edge 31a of the first layer 3a. Also, a metal film 35b may be formed together with the second metal film 30b on the connecting portion 35 of the first layer 3a by the same method as the second metal film 30b. As shown in FIG. 13, the second metal film 30b does not exhibit significant sedimentation with respect to the glaze layer 2. As shown in FIG. Further, as shown in FIG. 14, the thick-film printing of Ag paste for forming the third metal film 30c may be followed by the thick-film printing of the Ag-containing paste for forming the second metal film 30b. . Thereby, the third metal film 30c laminated on the second metal film 30b is obtained. In the illustrated state, the second metal film 30b and the third metal film 30c do not exhibit significant sedimentation with respect to the glaze layer 2. FIG.

Next, patterning using etching or the like is applied to the second metal film 30b. Thereby, the second layer 3b shown in FIG. 15 is obtained, and the electrode layer 3 composed of the first layer 3a, the second layer 3b and the third layer 3c is obtained. The second layer 3b has a covering portion 31b covering the first layer 3a and a sedimentation portion 32b in contact with the glaze layer 2 .

Thereafter, resistor layer 4 is formed by printing a thick film of a resistor paste containing a resistor such as ruthenium oxide and firing it. Also, the protective layer 55 is formed by, for example, printing a thick film of glass paste and baking it.

After the second layer 3b is formed by patterning the second metal film 30b and before the protective layer 55 is formed, the film is fired at a temperature higher than the normal firing temperature (eg, about 800° C.) by about 50° C., for example. It is preferred to carry out the steps. This may also serve as a baking step for the resistor layer 4, for example. As a result, at least part of the second layer 3b settles with respect to the glaze layer 2 to form a settled portion 32b. On the other hand, the first layer 3 a having the composition described above hardly settles on the glaze layer 2 .

Then, the thermal print head A1 is obtained by mounting the drive IC 71, bonding the wires 61, and attaching the substrate 1 and the wiring substrate 74 to the heat dissipation member 75.

It should be noted that the sedimentation state of the sedimentation portion 32b may vary depending on the setting of the conditions of the firing process for sedimentation of the sedimentation portion 32b of the second layer 3b. Besides the submerged conditions shown in FIGS. 5, 7 and 9, the submerged conditions shown in FIGS. 16 and 17 can be envisaged. In the modification shown in FIG. 16, all of the subsidence portions 32b subside with respect to the glaze layer 2. In the modification shown in FIG. In the modification shown in FIG. 17, part of the second layer 3b sinks with respect to the glaze layer 2, while another part of the second layer 3b is exposed from the glaze layer 2 upward in the z-direction.

18 and 19 show an embodiment of the thermal printhead A1. As shown in FIG. 19, the upper surface of the sedimented portion 32b in the z direction is substantially at the same height as the upper surface of the glaze layer 2 in the z direction. Since the second layer 3b is formed by thick-film printing and baking, the upper surface of the sedimentation portion 32b in the z-direction has a property with a certain degree of response. Therefore, as shown in FIG. 18, part of the sedimentation portion 32b is discretely exposed from the glaze layer 2. As shown in FIG. In the figure, a plurality of discrete portions indicated by hatching are portions where the sedimentation portion 32b exposed from the glaze layer 2 is visible through the protective layer 55. FIG.

Next, the operation of the thermal print head A1 and the method for manufacturing the thermal print head A1 will be described.

According to this embodiment, as shown in FIGS. 4 and 5, the resistor layer 4 is in contact with the first layer 3a of the electrode layer 3 and is not in contact with the second layer 3b. The first metal contained in the first layer 3a has a lower degree of diffusion into the resistor layer 4 than the second metal contained in the second layer 3b. Therefore, when a potential difference or temperature occurs between the electrode layer 3 and the resistor layer 4 during use of the thermal print head A1, the components constituting the electrode layer 3 can be prevented from diffusing into the resistor layer 4. It is possible. Therefore, deterioration of the electrode layer 3 and the resistor layer 4 can be suppressed.

In particular, when the resistor layer 4 is made of ruthenium oxide, the degree of diffusion of Ag becomes relatively large, and the degree of diffusion of Au can be kept relatively small. Also, by using Ag as the main component of the second layer 3b, the amount of Au used can be reduced, and the manufacturing cost of the thermal print head A1 can be reduced.

Since the sedimentation portion 32b of the second layer 3b is sedimented in the glaze layer 2, the sedimentation portion 32b can be protected by the glaze layer 2. As shown in FIG. Although the second layer 3 b is covered with the protective layer 55 , the protective layer 55 generally has a higher content of air bubbles and the like than the glaze layer 2 . In this regard, the configuration in which the sedimentation portion 32b is covered with the glaze layer 2, which can be easily finished as a relatively dense layer with few air bubbles due to the firing conditions, etc., is preferable for protecting the second layer 3b. Since the glaze layer 2 is made of glass, the sedimentation portion 32b can be intentionally deposited on the glaze layer 2 in the manufacturing process of the thermal print head A1.

According to the inventor's test, when the second layer 3b contains glass, it has been confirmed that the sedimentation part 32b tends to settle in the glaze layer 2 easily. On the other hand, it has been found that it is possible to prevent the first layer 3a from settling against the glaze layer 2 if the first layer 3a does not contain glass. Sedimentation of the second layer 3b is preferred for protection of the second layer 3b. On the other hand, avoiding sedimentation of the first layer 3a is preferable for ensuring electrical continuity between the first layer 3a and the resistor layer 4. FIG.

By configuring the bonding portion 39 with the second layer 3b and the third layer 3c, even if the subsidence portion 32b subsides significantly with respect to the glaze layer 2, the third layer 3c can be reliably separated from the glaze layer 2. can be exposed. Thereby, the wire 61 can be bonded to the bonding portion 39 . Also, the thickness of the bonding portion 39 is the sum of the thickness of the second layer 3b and the thickness of the third layer 3c. In bonding the wire 61 , pressure and vibration are applied to the bonding portion 39 . Since the bonding portion 39 is relatively thick, it is possible to avoid damage to the bonding portion 39 due to such an external load.

In this embodiment, as shown in FIGS. 10 and 11, the edge 301a of the first metal film 30a is left as the edge 31a of the first layer 3a in the method of manufacturing the thermal print head A1. Then, the second layer 3b is formed so as to cover the edge 31a. When the first metal film 30a is patterned by etching or the like, in the region where the first metal film 30a is removed by this patterning, a small amount of the first metal film 30a remains or the etching solution adheres unavoidably. . It has been found by the inventors' tests that such a region where such residual or adhesion occurs can cause a situation in which the second layer 3b is locally peeled off during the formation of the second layer 3b. In this embodiment, the edge 31a covered by the second layer 3b is an edge formed during thick film printing for forming the first metal film 30a, and an edge generated by patterning such as etching. is not. Therefore, in forming the second layer 3b, it is possible to prevent the portion of the sedimentation portion 32b adjacent to the edge 31a from unequally peeling off from the glaze layer 2. FIG. This is preferable for avoiding disconnection of the electrode layer 3 .

FIG. 20 shows another embodiment of the present disclosure. In addition, in the same figure, the same code|symbol as the said embodiment is attached|subjected to the same or similar element as the said embodiment.

A thermal print head A2 according to the second embodiment of the present disclosure shown in FIG. 20 differs from the above-described embodiments in the configuration of the glaze layer 2. In this embodiment, the glaze layer 2 has a heat storage portion 22 and an auxiliary portion 23 .

The heat accumulating portion 22 has a band shape extending in the main scanning direction x, and has an arcuate cross-section that bulges slightly upward in the figure. The resistor layer 4 is formed on the heat storage section 22 . The heat storage part 22 is for suppressing excessive transmission of the heat generated from the heat generating part 41 of the resistor layer 4 to the substrate 1 . A plurality of common electrode strip portions 34 of the common electrode 33 and individual electrode strip portions 38 of a plurality of individual electrodes 36 are formed on the heat storage portion 22 .

Auxiliary portion 23 is formed to cover a portion of substrate 1 exposed from heat storage portion 22 . The heat storage part 22 is for forming a smooth surface suitable for forming the electrode layer 3 by covering the relatively rough surface of the substrate 1 .

Heat storage portion 22 and auxiliary portion 23 are made of glass, for example. The specific selection of such glass is made in view of sufficiently exhibiting the heat storage function of the heat storage portion 22 and the smoothing function of the auxiliary portion 23 . As the material of the auxiliary portion 23, it is preferable to use a glass paste having a viscosity lower than that of the glass paste used as the material of the heat storage portion 22. FIG.

Deterioration of the electrode layer 3 and the resistor layer 4 can be suppressed also by such an embodiment.

The first and second embodiments include the following remarks.
[Appendix 1]
a substrate;
an electrode layer;
A thermal printhead comprising a resistor layer including a plurality of heat generating portions arranged in the main scanning direction,
The electrode layer includes a first layer interposed between the resistor layer and the substrate, and a second layer separated from the resistor layer and having a covering portion formed on the first layer. have
The thermal print head, wherein the first metal contained in the first layer has a smaller degree of diffusion into the resistor layer than the second metal contained in the second layer.
[Appendix 2]
10. The thermal printhead of Claim 1, comprising a glaze layer formed on the substrate. [Appendix 3]
2. The thermal printhead according to appendix 2, wherein the second layer has a sedimentation portion, at least a part of which is sedimented in the glaze layer.
[Appendix 4]
4. The thermal printhead of Claim 3, wherein the glaze layer is made of glass.
[Appendix 5]
5. The thermal printhead according to appendix 3 or 4, wherein the second layer has a covering portion covering a portion of the first layer.
[Appendix 6]
6. The thermal printhead of Claim 5, wherein the second layer is thicker than the first layer.
[Appendix 7]
7. The thermal printhead of Claim 6, wherein the first metal is Au.
[Appendix 8]
8. The thermal printhead of Claim 7, wherein the second metal is Ag.
[Appendix 9]
9. The thermal printhead of Clause 8, wherein the second layer comprises glass.
[Appendix 10]
10. The thermal printhead of any of Clauses 7-9, wherein the resistor layer comprises ruthenium oxide.
[Appendix 11]
11. The thermal printhead according to any one of appendices 7 to 10, wherein the substrate is made of ceramics.
[Appendix 12]
12. The thermal printhead of clause 11, wherein the substrate is made of AlN.
[Appendix 13]
The electrode layer includes a common electrode having a connecting portion extending in the main scanning direction and a plurality of common electrode strip portions extending from the connecting portion in the sub-scanning direction, and a common electrode extending in the sub-scanning direction and adjacent to each other in the main scanning direction. 13. A thermal printhead according to any one of Clauses 5 to 12, comprising a plurality of individual electrodes each having an individual electrode strip located between the mating common electrode strips.
[Appendix 14]
14. The thermal printhead of Clause 13, wherein the resistor layer intersects the plurality of common electrode strips and the plurality of individual electrode strips.
[Appendix 15]
15. The thermal printhead of Claim 14, wherein the plurality of common electrode strips and the plurality of individual electrode strips are interposed between the substrate and the resistor layer.
[Appendix 16]
16. The thermal printhead of Claim 15, wherein the plurality of common electrode strips and the plurality of individual electrode strips are configured by the first layer.
[Appendix 17]
17. The thermal printhead according to appendix 16, wherein the resistor layer is strip-shaped and elongated in the main scanning direction.
[Appendix 18]
18. The thermal printhead according to appendix 16 or 17, wherein the individual electrode has a bonding portion to which a wire is bonded, located on the side opposite to the individual electrode strip portion in the sub-scanning direction.
[Appendix 19]
The electrode layer has a third layer containing a third metal, laminated on the second layer,
19. The thermal printhead according to appendix 18, wherein the bonding portion is composed of the second layer and the third layer.
[Appendix 20]
20. The thermal printhead of Claim 19, wherein the third layer is exposed from the glaze layer.
[Appendix 21]
21. The thermal printhead of Clause 20, wherein the third metal is the same as the second metal.
[Appendix 22]
22. The thermal printhead of Clause 21, wherein the wires are made of Au.
[Appendix 23]
23. A thermal printhead according to any one of Clauses 5 to 22, comprising a protective layer covering the resistor layer.
[Appendix 24]
24. The thermal printhead of Claim 23, wherein the protective layer is made of glass.
[Appendix 25]
forming a glaze layer on a substrate;
forming a first metal film containing a first metal on the glaze layer;
forming a first layer by patterning the first metal film;
forming a second metal film containing a second metal covering at least a portion of the first layer;
forming a second layer by patterning the second metal film;
forming a resistor layer covering a portion of the first layer and spaced apart from the second layer;
with
The method of manufacturing a thermal print head, wherein the first metal has a smaller degree of diffusion into the resistor layer than the second metal.
[Appendix 26]
26. The method of manufacturing a thermal print head according to appendix 25, wherein the step of forming the first metal film includes a step of printing a first paste containing the first metal, and a step of firing the first paste. .
[Appendix 27]
27. The method of manufacturing a thermal print head according to appendix 26, wherein the step of forming the second metal film includes a step of printing a second paste containing the second metal, and a step of firing the second paste. .
[Appendix 28]
In the step of forming the first layer, part of the edge of the first metal film remains as the edge of the first layer;
28. The method of manufacturing a thermal printhead according to appendix 27, wherein in the step of forming the second metal film, the edge of the first layer is covered with the second metal film.
[Appendix 29]
29. The method of manufacturing a thermal printhead according to any one of Appendices 25 to 28, wherein the glaze layer is made of glass.
[Appendix 30]
29. The method of manufacturing a thermal printhead according to appendix 29, wherein the first metal is Au. [Appendix 31]
31. The method of manufacturing a thermal printhead according to appendix 30, wherein the second metal is Ag. [Appendix 32]
32. The method of claim 31, wherein the second layer comprises glass. [Appendix 33]
33. The method of manufacturing a thermal printhead according to any one of Appendices 29 to 32, wherein the resistor layer contains ruthenium oxide.

21-27 show an example of a thermal printhead according to the present disclosure. The thermal printhead A1 of this embodiment includes a substrate 1, a glaze layer 2, an electrode layer 3, a resistor layer 4, a protective layer 55, a drive IC 71, a sealing resin 72, a connector 73, a wiring board 74 and a heat dissipation member 75. ing. The thermal print head A1 is incorporated in a printer for printing on thermal paper to create bar code sheets and receipts, for example. For convenience of understanding, the protective layer 55 is omitted in FIGS. 21, 23, 24 and 26. FIG. In these figures, the main scanning direction is the x direction, the sub-scanning direction is the y direction, and the thickness direction of the substrate 1 is the z direction.

FIG. 21 is a plan view showing the thermal print head A1. 22 is a cross-sectional view taken along line XXII-XXII of FIG. 21. FIG. FIG. 23 is an enlarged plan view of the main part showing the thermal print head A1. FIG. 24 is an enlarged plan view of the main part showing the thermal print head A1. FIG. 25 is an enlarged cross-sectional view of a main part taken along line XXV--XXV of FIG. FIG. 26 is an enlarged plan view of the main part showing the thermal print head A1. FIG. 27 is a cross-sectional view of essential parts along line XXVII-XXVII of FIG.

The substrate 1 is made of ceramic such as AlN or Al ₂ O ₃ and has a thickness of about 0.6 to 1.0 mm. As shown in FIG. 21, the substrate 1 has a long rectangular shape extending in the main scanning direction x. As shown in FIG. 22, in addition to the substrate 1, a wiring substrate 74 may be provided in which a substrate layer made of glass epoxy resin and a wiring layer made of Cu or the like are laminated. A heat radiating member 75 made of a metal such as Al is provided on the lower surface of the substrate 1 . In the configuration having the wiring substrate 74, for example, the substrate 1 and the wiring substrate 74 are arranged adjacently on the heat radiating member 75, and the wiring between the electrode layer 3 on the substrate 1 and the wiring substrate 74 (or the IC connected to this wiring). ) are connected, for example, by wire bonding. Furthermore, a connector 73 shown in FIG. 21 may be provided on the wiring board 74 .

Glaze layer 2 is formed on substrate 1 and is made of a glass material such as amorphous glass. The softening point of this glass material is, for example, 800-850.degree. The glaze layer 2 is formed by printing a thick film of glass paste and then firing it. In this embodiment, the entire upper surface of the substrate 1 in the figure is covered with the glaze layer 2 .

The electrode layer 3 constitutes a path for energizing the resistor layer 4, and is made of a conductive material. The electrode layer 3 has a first layer 3a and a second layer 3b. Furthermore, in this embodiment, as shown in FIGS. 26 and 27, the electrode layer 3 further has a third layer 3c.

The first layer 3a is formed on the glaze layer 2, and is made of Au or Pt to which rhodium, vanadium, bismuth, silicon, or the like is added as an additive element, for example. In this embodiment, the main component of the first layer 3a is Au, and Au corresponds to an example of the first metal. The first layer 3a is formed by thick-film-printing a resinate Au paste containing an organic compound and then firing the paste. Such a first layer 3a contains glass through a firing process. The glass has a relatively small particle size, for example an average particle size of 0.01 μm to 0.1 μm. The content of glass in the first layer 3a is, for example, 5 wt % to 10 wt %. The first layer 3a may be configured by laminating a plurality of Au layers. The thickness of first layer 3a is, for example, about 0.4 to 1.0 μm.

Further, the edge 31a, which is the upstream end in the sub-scanning direction y of the first layer 3a, is a slightly thicker portion as shown in FIG. 25 due to the manufacturing method to be described later.

A part of the second layer 3 b is formed on the first layer 3 a and the other part is formed on the glaze layer 2 . Also, the second layer 3 b is separated from the resistor layer 4 . The second layer 3b has a lower layer 31b and an upper layer 32b.

The lower layer 31b contains at least one of Ag, Cu and Al as the second metal and glass. In this embodiment, the case where Ag is selected as the second metal will be described as an example. In this embodiment, the lower layer 31b is doped with Au in a weight ratio of about 0.01% to 0.3% with respect to Ag as the second metal. The lower layer 31b is formed by printing a resinate Ag paste containing an organic compound as a thick film and then firing the paste. Ag as the second metal in the lower layer 31b has an average grain size of, for example, 0.01 μm to 0.1 μm. Further, the lower layer 31b contains glass through a firing process. The glass has a relatively small particle size, for example, an average particle size of 0.01 μm to 0.1 μm. The content of glass in the lower layer 31b is, for example, 5 wt % to 10 wt %. The thickness of the lower layer 31b is, for example, 0.8 μm to 1.2 μm, and is usually thicker than the first layer 3a.

The upper layer 32b contains at least one of Ag, Cu, and Al as the second metal and glass. In this embodiment, the case where Ag is selected as the second metal will be described as an example. The upper layer 32b is formed by printing a thick film of a glass frit Ag paste containing Ag and glass frit, and then firing it. Ag as the second metal in the upper layer 32b has an average grain size of, for example, 0.5 μm to 3 μm, which is larger than the grain size in the lower layer 31b. Also, the upper layer 32b includes a glass frit. Also, the upper layer 32b may contain an additive element such as Pd. The thickness of the upper layer 32b is, for example, 2 μm to 5 μm, and is usually thicker than the lower layer 31b and the first layer 3a.

The glass frit of the upper layer 32b has a relatively larger particle size than the glass of the first layer 3a and the lower layer 31b, and has an average particle size of 0.3 μm to 1.0 μm, for example. The glass content of the first layer 3a and the lower layer 31b is smaller than the glass content of the upper layer 32b, for example 1% to 5% by weight. Also, the grain size of Ag as the second metal in the lower layer 31b is smaller than the grain size of Ag as the second metal in the upper layer 32b. Furthermore, Au as the first metal has a smaller degree of diffusion into the resistor layer 4, which will be described later, than Ag as the second metal.

The third layer 3c is laminated on the upper layer 32b of the second layer 3b. In the present embodiment, the third layer 3c has the same composition as the upper layer 32b and contains Ag as a main component. The thickness of the third layer 3c is not particularly limited, and is the same as that of the upper layer 32b in this embodiment.

As shown in FIG. 23 , the electrode layer 3 has a common electrode 33 and multiple individual electrodes 36 .

The common electrode 33 has a plurality of common electrode strip portions 34 and common electrode connecting portions 35 . The common electrode connecting portion 35 is arranged near the downstream end in the sub-scanning direction y of the substrate 1 and has a strip shape extending in the main scanning direction x. The plurality of common electrode strip portions 34 each extend in the sub-scanning direction y from the common electrode connecting portion 35 and are arranged at equal pitches in the main scanning direction x. In addition, in the present embodiment, as shown in FIG. 24, an Ag layer 351 is laminated on the common electrode connecting portion 35 . The Ag layer 351 is for reducing the resistance value of the common electrode connection portion 35 .

The plurality of individual electrodes 36 is for partially energizing the resistor layer 4 and is a portion having a polarity opposite to that of the common electrode 33 . The individual electrode 36 extends from the resistor layer 4 toward the drive IC 71 . A plurality of individual electrodes 36 are arranged in the main scanning direction x, each having an individual electrode strip portion 38 , an individual electrode connecting portion 37 and a bonding portion 39 .

Each individual electrode strip portion 38 is a strip portion extending in the sub-scanning direction y and positioned between two adjacent common electrode strip portions 34 of the common electrode 33 . The individual electrode strip portion 38 of the individual electrode 36 and the common electrode strip portion 34 of the common electrode 33 have a width of, for example, 25 μm or less. The distance from the belt-like portion 34 is, for example, 40 μm or less.

The individual electrode connecting portion 37 is a portion extending from the individual electrode strip portion 38 toward the drive IC 71, and most of the portion has a portion along the sub-scanning direction y and a portion inclined with respect to the sub-scanning direction y. . The width of most of the individual electrode connecting portions 37 is, for example, 40 μm or less, and the distance between adjacent individual electrode connecting portions 37 is, for example, 40 μm or less. In the illustrated example, the width of the individual electrode connecting portion 37 is larger than the width of the individual electrode strip portion 38 .

As shown in FIGS. 26 and 27, the bonding portion 39 is formed at the y end of the individual electrode 36 in the sub-scanning direction, and a wire 61 for connecting the individual electrode 36 and the drive IC 71 is bonded. . The bonding portions 39 of adjacent individual electrodes 36 are arranged alternately in the sub-scanning direction y. As a result, although the bonding portions 39 are wider than most of the individual electrode connecting portions 37, they are prevented from interfering with each other.

A portion of the individual electrode connecting portion 37 sandwiched between the adjacent bonding portions 39 has the smallest width of the individual electrode 36, for example, 10 μm or less. Also, the distance between the individual electrode connecting portion 37 and the adjacent bonding portion 39 is, for example, 10 μm or less. Thus, the common electrode 33 and the plurality of individual electrodes 36 are fine patterns with small line widths and small line intervals.

As shown in FIGS. 24 and 25, the plurality of common electrode strip portions 34 of the common electrode 33 and the individual electrode strip portions 38 of the plurality of individual electrodes 36 are composed only of the first layer 3a.

As shown in FIGS. 24 and 25, the lower layer 31b has a lower layer covering portion 311b. The lower layer covering portion 311b is formed on the first layer 3a and covers the first layer 3a. In addition, the lower layer 31b has a portion formed on the glaze layer 2 .

The upper layer 32b has an upper layer covering portion 321b. The upper layer covering portion 321b is formed on the lower layer 31b and covers the lower layer 31b. Also, the upper layer covering portion 321b is not in contact with the first layer 3a. In the illustrated example, the upper layer covering portion 321b is formed on the lower layer covering portion 311b and covers the lower layer covering portion 311b. That is, the upper layer covering portion 321b overlaps the first layer 3a when viewed in the z direction.

Also, in this embodiment, the upper layer 32b has a sedimentation portion 322b. The sedimented portion 322 b is a portion of the second layer 3 b that is formed directly on the glaze layer 2 , and at least part of it is sedimented onto the glaze layer 2 . Note that the upper layer 32b may be configured without the sedimentation portion 322b.

As shown in FIGS. 24 and 25, in this embodiment, most of the individual electrode connecting portions 37 of the plurality of individual electrodes 36 are composed only of the sedimentation portions 322b. In this embodiment, the first layer 3a and the lower layer 31b are hardly sedimented with respect to the glaze layer 2. As shown in FIG. As a result, the upper layer covering portion 321b does not settle with respect to the glaze layer 2 . As shown in FIGS. 24 and 25, the lower layer 31b and the upper layer 32b cover the edge 31a of the first layer 3a.

As shown in FIGS. 26 and 27, in this embodiment, the bonding portion 39 is composed of the upper layer 32b of the second layer 3b and the third layer 3c. As shown in FIG. 27, the upper layer 32b that constitutes the bonding portion 39 is a sedimented portion 322b, at least a part of which is sedimented with respect to the glaze layer 2. As shown in FIG. On the other hand, the third layer 3c is formed on the upper layer 32b, and at least a part of it is exposed from the glaze layer 2, and in this embodiment, most of it does not settle with respect to the glaze layer 2. .

The resistor layer 4 is made of, for example, ruthenium oxide, which has a higher resistivity than the material forming the electrode layer 3, and is formed in a strip shape extending in the main scanning direction x. The resistor layer 4 intersects a plurality of common electrode strips 34 of the common electrode 33 and individual electrode strips 38 of a plurality of individual electrodes 36 . Furthermore, the resistor layer 4 is laminated on the side opposite to the substrate 1 with respect to the plurality of common electrode strip portions 34 of the common electrode 33 and the individual electrode strip portions 38 of the plurality of individual electrodes 36 . That is, the resistor layer 4 is in contact only with the first layer 3 a of the electrode layer 3 . A portion of the resistor layer 4 sandwiched between the common electrode strip portions 34 and the individual electrode strip portions 38 is a heat generating portion 41 that generates heat by being partially energized by the electrode layer 3 . Print dots are formed by the heat generated by the heating portion 41 . The thickness of resistor layer 4 is, for example, 4 μm to 6 μm.

The protective layer 55 is for protecting the electrode layer 3 and the resistor layer 4 . Protective layer 55 is made of, for example, amorphous glass. However, the protective layer 55 exposes regions including the bonding portions 39 of the plurality of individual electrodes 36 .

The drive IC 71 performs a function of partially heating the resistor layer 4 by selectively energizing the plurality of individual electrodes 36 . The driving IC 71 is provided with a plurality of pads. Pads of the drive IC 71 and the plurality of individual electrodes 36 are connected via a plurality of wires 61 bonded to each. The wire 61 is made of Au. As shown in FIGS. 21 and 22, drive IC 71 and wires 61 are covered with sealing resin 72 . The sealing resin 72 is made of, for example, a black soft resin. Further, the driving IC 71 and the connector 73 are connected by a signal line (not shown).

Next, an example of a method for manufacturing the thermal print head A1 will be described below with reference to FIGS. 28 to 34. FIG.

First, as shown in FIG. 28, a substrate 1 made of AlN, for example, is prepared. Next, after a thick film of glass paste is printed on the substrate 1, the glaze layer 2 is formed by firing the paste. Next, a resinate Au paste (an example of a resinate first metal paste) is thick-film-printed and then fired to form the first metal film 30a. The thick film printing and baking steps may be repeated multiple times. In the illustrated example, the formation area of the first metal film 30a is a limited area in the sub-scanning direction y. The first metal film 30a has an edge 301a extending in the main scanning direction x.

Next, the first layer 3a shown in FIG. 29 is formed by patterning the first metal film 30a using, for example, etching. The first layer 3a has portions that become a plurality of common electrode strip portions 34, a plurality of individual electrode strip portions 38, a common electrode connecting portion 35, and the like. The first layer 3a also has an edge 31a. The edge 31a is a part where the edge 301a of the first metal film 30a remains. That is, the edge 31a is not formed by etching or the like for patterning the first metal film 30a.

Next, as shown in FIG. 30, a lower metal film 310b is formed. The lower layer metal film 310b is formed by thick-film printing the resinate Ag paste containing Ag (an example of the resinate second metal paste) in a predetermined region including the region to be the individual electrode connecting portion 37, and then firing the paste. by doing. In the illustrated example, the lower metal film 310b is formed to cover the edge 31a of the first layer 3a.

Next, as shown in FIG. 31, an upper metal film 320b is formed. The formation of the upper layer metal film 320b is carried out by thick-film printing the glass frit Ag paste (glass frit second metal paste) containing Ag and glass frit described above so as to cover the lower layer metal film 310b, and then firing this. . In this embodiment, the upper metal film 320b is applied to the region overlapping with the first layer 3a through the lower metal film 310b, and covers most of the lower metal film 310b. Also, the metal film 35b may be formed together with the second metal film 30b on the common electrode connecting portion 35 of the first layer 3a by the same method as the upper metal film 320b. As shown in FIG. 32, the upper metal film 320b does not exhibit significant sedimentation with respect to the glaze layer 2. FIG. Further, after the thick-film printing of the Ag-containing paste for forming the upper metal film 320b, the Ag paste for forming the third layer 3c may be thick-film-printed.

Then, the lower metal film 310b and the upper metal film 320b are patterned by etching or the like. Thereby, the second layer 3b having the lower layer 31b and the upper layer 32b shown in FIG. 33 is obtained, and the electrode layer 3 composed of the first layer 3a, the second layer 3b and the third layer 3c is obtained.

Thereafter, resistor layer 4 is formed by printing a thick film of a resistor paste containing a resistor such as ruthenium oxide and firing it. Also, the protective layer 55 is formed by, for example, printing a thick film of glass paste and baking it.

After forming the second layer 3b having the lower layer 31b and the upper layer 32b by patterning the lower layer metal film 310b and the upper layer metal film 320b, before forming the protective layer 55, a normal firing temperature (for example, about 800° C. ), it is preferable to carry out the firing step at a temperature higher than that by about 50° C., for example. This may also serve as a baking step for the resistor layer 4, for example. As a result, at least a portion of the upper layer 32b sinks with respect to the glaze layer 2 to form a sinking portion 322b. On the other hand, the first layer 3a and the lower layer 31b having the compositions described above hardly settle with respect to the glaze layer 2 . A manufacturing method that does not include the sedimentation step may be used.

Then, the thermal print head A1 is obtained by mounting the drive IC 71, bonding the wires 61, and attaching the substrate 1 and the wiring substrate 74 to the heat dissipation member 75.

Next, the operation of the thermal print head A1 and the method for manufacturing the thermal print head A1 will be described.

According to this embodiment, as shown in FIGS. 24 and 25, the lower layer 31b is interposed between the first layer 3a and the upper layer 32b, and the first layer 3a and the upper layer 32b are not in contact with each other. After the formation of the first metal film 30a shown in FIG. 30, patterning for forming the first layer 3a is performed. A glass component or the like contained in the first metal film 30a may remain in the portion where the first metal film 30a is exposed. If the upper metal film 320b is directly formed on the glaze layer 2 in which such a glass component remains, the second metal of the upper metal film 320b remains on the glaze layer 2 even if the patterning for forming the second layer 3b is performed. The research by the inventors has revealed that there is a great possibility that Ag, which is the above, may remain. Such residual Ag can be a cause of improper conduction between the adjacent individual electrode strip portions 38 . In this embodiment, it is not necessary to form the upper metal film 320b on the glaze layer 2 on which the first metal film 30a is formed. Furthermore, according to the research of the inventors, even if the above-mentioned glass remains in the glaze layer 2, when the lower metal film 310b formed by printing and baking the resinate Ag paste is removed by patterning, the lower metal film 310b is It was found that Ag residue and the like did not occur. This was the same even when the upper metal film 320b was formed on the lower metal film 310b and the lower metal film 310b and the upper metal film 320b were removed by patterning. Therefore, according to the thermal print head A1, it is possible to avoid undue conduction between the adjacent individual electrode connecting portions 37, and the pitch between the common electrode 33 and the individual electrodes 36 can be further reduced. Therefore, high-definition printing of the thermal print head A1 can be achieved.

Further, the upper layer 32b formed using the glass frit Ag paste is thicker than the lower layer 31b formed using the resinate Ag paste and is easier to finish. Therefore, forming a larger region of the individual electrode 36 with the second layer 3b is advantageous in reducing the resistance of the individual electrode 36. FIG.

In this embodiment, the resistor layer 4 is in contact only with the first layer 3a and is not in contact with the second layer 3b. Au as the first metal contained in the first layer 3a has a smaller degree of diffusion into the resistor layer 4 than Ag as the second metal contained in the second layer 3b. Therefore, when a potential difference or temperature occurs between the electrode layer 3 and the resistor layer 4 during use of the thermal print head A1, the components constituting the electrode layer 3 can be prevented from diffusing into the resistor layer 4. It is possible. Therefore, deterioration of the electrode layer 3 and the resistor layer 4 can be suppressed.

As shown in FIGS. 24 and 25, the lower layer covering portion 311b of the lower layer 31b is exposed from the upper layer 32b on the first layer 3a. Due to the presence of the exposed portion of the lower layer covering portion 311b, contact between the upper layer 32b and the first layer 3a can be more reliably prevented.

In the present embodiment, the upper layer covering portion 321b overlaps the first layer 3a as viewed in the z-direction via the lower layer 31b. That is, in the region of the individual electrode connecting portion 37 that does not include the first layer 3a, there is no portion that forms a conductive path only by the lower layer 31b, and the individual electrode connecting portion 37 is formed by both the lower layer 31b and the upper layer 32b. ing. This is preferable for reducing the resistance of the individual electrode 36 .

Since the sedimentation part 322b of the upper layer 32b of the second layer 3b is sedimented in the glaze layer 2, the sedimentation part 322b can be protected by the glaze layer 2. As shown in FIG. Although the second layer 3 b is covered with the protective layer 55 , the protective layer 55 generally has a higher content of air bubbles and the like than the glaze layer 2 . In this regard, the configuration in which the sedimentation portion 322b is covered with the glaze layer 2, which can be easily finished as a relatively dense layer with few air bubbles due to the firing conditions, etc., is preferable for protecting the second layer 3b. Since the glaze layer 2 is made of glass, the sedimentation portion 322b can be intentionally deposited on the glaze layer 2 in the manufacturing process of the thermal print head A1.

By configuring the bonding portion 39 with the upper layer 32b of the second layer 3b and the third layer 3c, even if the sinking portion 322b subsides remarkably with respect to the glaze layer 2, the third layer 3c can be attached to the glaze layer 2. can be reliably exposed from Thereby, the wire 61 can be bonded to the bonding portion 39 . Also, the thickness of the bonding portion 39 is the sum of the thickness of the upper layer 32b and the thickness of the third layer 3c. In bonding the wire 61 , pressure and vibration are applied to the bonding portion 39 . Since the bonding portion 39 is relatively thick, it is possible to avoid damage to the bonding portion 39 due to such an external load.

FIG. 35 is an enlarged plan view showing a specific example of the individual electrode connecting portion 37 of the thermal print head A1, showing only the first layer 3a, the lower layer 31b and the upper layer 32b. In addition, in the same drawing, a formation range of the lower layer 31b is clearly shown by removing a part of the upper layer 32b for illustration, and the removed upper layer 32b is indicated by an imaginary line.

In the manufacturing method described with reference to FIGS. 28 to 34, the width setting of the first layer 3a, the lower layer 31b and the upper layer 32b in the individual electrode connecting portion 37 is not specifically intended, and they may have the same width. , may differ within the scope of the configurations described above. The specific example shown in the figure is formed under the idea that the first layer 3a, the lower layer 31b, and the upper layer 32b have approximately the same width.

In the illustrated example, the width W21 of the lower layer 31b is narrower than the width W1 of the first layer 3a, and the width W22 of the upper layer 32b is wider. This is because, in the manufacturing method described above, when the lower layer 31b and the upper layer 32b are collectively patterned, the lower metal film 310b exists as a single layer rather than the laminated portion of the lower metal film 310b and the upper metal film 320b. This is due to the fact that the removal of the portion is more likely to proceed by etching or the like. Therefore, even if the lower layer 31b and the upper layer 32b are finished to have the same width, the width W21 of the lower layer 31b tends to be narrower than the width W22 of the upper layer 32b. If such a tendency occurs, from the viewpoint of avoiding a large divergence between the width W21, the width W22, and the width W1, it is preferable to adopt the illustrated size relationship.

Figures 36 and 37 show another embodiment of the present disclosure. In addition, in the same figure, the same code|symbol as the said embodiment is attached|subjected to the same or similar element as the said embodiment.

FIG. 36 shows a thermal printhead according to a fourth embodiment of the present disclosure. In the thermal print head A2 of this embodiment, the laminated structure of the first layer 3a, the lower layer 31b and the upper layer 32b in the individual electrode connecting portion 37 is different from that of the embodiment described above.

In this embodiment, the upper layer covering portion 321b of the upper layer 32b overlaps with the lower layer 31b, but does not overlap with the first layer 3a and the lower layer covering portion 311b. That is, the upper layer 32b is separated from the first layer 3a when viewed in the z direction. A second layer 3b composed only of the lower layer 31b exists between the first layer 3a (lower layer covering portion 311b) and the upper layer 32b (upper layer covering portion 321b).

According to such an embodiment as well, it is possible to achieve high-definition printing of the thermal print head A2. Further, in this embodiment, the upper layer 32b is formed in a region separated from the edge 31a of the first layer 3a in the sub-scanning direction y. Therefore, the upper metal film 320b for forming the upper layer 32b can be provided in a region completely separated from the region where the first metal film 30a for forming the first layer 3a was formed. This is suitable for avoiding the above-described unintended remaining of the upper metal film 320b.

A thermal printhead A3 according to the fifth embodiment of the present disclosure shown in FIG. 37 differs from the embodiments described above in the configuration of the glaze layer 2 . In this embodiment, the glaze layer 2 has a heat storage portion 22 and an auxiliary portion 23 .

The heat accumulating portion 22 has a band shape extending in the main scanning direction x, and has an arcuate cross-section that bulges slightly upward in the figure. The resistor layer 4 is formed on the heat storage section 22 . The heat storage part 22 is for suppressing excessive transmission of the heat generated from the heat generating part 41 of the resistor layer 4 to the substrate 1 . A plurality of common electrode strip portions 34 of the common electrode 33 and individual electrode strip portions 38 of a plurality of individual electrodes 36 are formed on the heat storage portion 22 .

Auxiliary portion 23 is formed to cover a portion of substrate 1 exposed from heat storage portion 22 . The heat storage part 22 is for forming a smooth surface suitable for forming the electrode layer 3 by covering the relatively rough surface of the substrate 1 .

Heat storage portion 22 and auxiliary portion 23 are made of glass, for example. The specific selection of such glass is made in view of sufficiently exhibiting the heat storage function of the heat storage portion 22 and the smoothing function of the auxiliary portion 23 . As the material of the auxiliary portion 23, it is preferable to use a glass paste having a viscosity lower than that of the glass paste used as the material of the heat storage portion 22. FIG.

According to such an embodiment as well, it is possible to achieve high-definition printing of the thermal print head A3.

The third to fifth embodiments include the following remarks.
[Appendix 1]
a substrate;
an electrode layer;
A thermal printhead comprising a resistor layer including a plurality of heat generating portions arranged in the main scanning direction,
The electrode layer has a first layer interposed between the resistor layer and the substrate, and a second layer separated from the resistor layer and electrically connected to the first layer,
the first layer comprises a first metal and glass;
The second layer includes a lower layer containing a second metal and glass and having a lower layer covering portion covering the first layer, and an upper layer containing the second metal and glass and not in contact with the first layer and covering the lower layer. an upper layer having a covering,
The thermal printhead, wherein the lower layer has a lower glass content than the upper layer.
[Appendix 2]
2. The thermal printhead of claim 1, wherein the lower layer glass has a smaller particle size than the upper layer glass.
[Appendix 3]
2. The thermal printhead according to appendix 2, wherein the second metal in the lower layer has a smaller grain size than the second metal in the upper layer.
[Appendix 4]
4. The thermal printhead according to any one of Appendices 1 to 3, wherein the first metal has a smaller degree of diffusion into the resistor layer than the second metal.
[Appendix 5]
5. The thermal printhead according to any one of Appendices 1 to 4, wherein the lower layer is thinner than the upper layer.
[Appendix 6]
6. The thermal printhead of Claim 5, wherein the second layer is thicker than the first layer.
[Appendix 7]
7. The thermal printhead of Claim 6, wherein the lower layer is thicker than the first layer.
[Appendix 8]
8. The thermal printhead according to any one of appendices 1 to 7, wherein the first metal is Au.
[Appendix 9]
9. The thermal printhead according to any one of Appendices 1 to 8, wherein the second metal is Ag.
[Appendix 10]
10. The thermal printhead of any one of Appendixes 1-9, wherein the resistor layer comprises ruthenium oxide.
[Appendix 11]
11. The thermal printhead according to any one of Appendices 1 to 10, wherein the lower layer covering portion is exposed from the upper layer.
[Appendix 12]
12. The thermal printhead according to Appendix 11, wherein the upper layer covering portion overlaps the first layer in plan view.
[Appendix 13]
13. The thermal printhead of any one of Appendixes 1-12, comprising a glaze layer formed on the substrate.
[Appendix 14]
14. The thermal printhead of Claim 13, wherein the glaze layer is made of glass.
[Appendix 15]
15. The thermal printhead according to any one of appendices 1 to 14, wherein the substrate is made of ceramics.
[Appendix 16]
16. The thermal printhead of clause 15, wherein the substrate is made of AlN.
[Appendix 17]
The electrode layer includes a common electrode having a common electrode connection portion extending in the main scanning direction and a plurality of common electrode strip portions extending in the sub-scanning direction from the common electrode connection portion; 13. A thermal printhead according to any one of Clauses 1 to 12, comprising a plurality of individual electrodes each having an individual electrode strip located between said common electrode strips adjacent in the scanning direction.
[Appendix 18]
18. The thermal printhead of Clause 17, wherein the resistor layer intersects the plurality of common electrode strips and the plurality of individual electrode strips.
[Appendix 19]
19. The thermal printhead of Clause 18, wherein the plurality of common electrode strips and the plurality of individual electrode strips are interposed between the substrate and the resistor layer.
[Appendix 20]
20. The thermal printhead of Claim 19, wherein the plurality of common electrode strips and the plurality of individual electrode strips are configured by the first layer.
[Appendix 21]
The individual electrode has an individual electrode connecting portion that is connected to the individual electrode strip portion on the side opposite to the resistor layer in the sub-scanning direction,
21. The thermal printhead according to appendix 20, wherein the individual electrode connecting portion is composed of the first layer and the second layer.
[Appendix 22]
22. The thermal printhead according to appendix 21, wherein the width of the lower layer covering portion exposed from the upper layer in the individual electrode connecting portion is smaller than the width of the upper layer.
[Appendix 23]
23. A thermal printhead according to any one of the appendices 1 to 22, comprising a protective layer covering the resistor layer.
[Appendix 24]
24. The thermal printhead of Claim 23, wherein the protective layer is made of glass.
[Appendix 25]
forming a glaze layer on a substrate;
forming a first metal film containing a first metal on the glaze layer;
forming a first layer by patterning the first metal film;
forming a lower layer metal film containing a second metal covering at least a portion of the first layer;
forming an upper metal film containing the second metal that covers at least a portion of the lower metal film and does not contact the first metal film;
forming a second layer by patterning the lower metal film and the upper metal film;
forming a resistor layer covering a portion of the first layer and spaced apart from the second layer;
with
The step of forming the lower layer metal film includes a step of applying a resinate second metal paste containing the second metal and an organic compound by printing, and a step of firing the resinate second metal paste,
In the step of forming the upper layer metal film, a step of applying a glass frit second metal paste containing the second metal and a glass frit by printing, and a step of firing the glass frit second metal paste. A method for manufacturing a thermal printhead.
[Appendix 26]
The step of forming the first metal film includes a step of applying a resinate first metal paste containing the first metal and an organic compound by printing, and a step of firing the resinate first metal paste. 26. The method of manufacturing a thermal printhead according to 25 above.
[Appendix 27]
27. The method of manufacturing a thermal print head according to appendix 25 or 26, wherein in the step of forming the second layer, the second layer is formed so as to overlap the first layer in plan view.
[Appendix 28]
28. The method of manufacturing a thermal printhead according to any one of Appendices 25 to 27, wherein the first metal is Au.
[Appendix 29]
29. The method of manufacturing a thermal printhead according to any one of appendices 25 to 28, wherein the second metal is Ag.

The thermal printhead and the method of manufacturing the thermal printhead according to the present disclosure are not limited to the embodiments described above. The specific configuration of the thermal printhead and the method of manufacturing the thermal printhead according to the present disclosure can be modified in various ways.

A1, A2: Thermal print head 1 : Substrate 2 : Glaze layer 3 : Electrode layer 3a : First layer 3b : Second layer 3c : Third layer 4 : Resistor layer 22 : Heat storage section 23 : Auxiliary section 30a : First Metal film 30b : Second metal film 30c : Third metal film 31a : Edge 31b : Coating portion 32b : Sedimentation portion 33 : Common electrode 34 : Common electrode strip portion 35 : Connecting portion 35b : Metal film 36 : Individual electrode 37 : Connecting portion 38 : Individual electrode strip portion 39 : Bonding portion 41 : Heat generating portion 55 : Protective layer 61 : Wire 72 : Sealing resin 73 : Connector 74 : Wiring substrate 75 : Heat dissipation member 301a : Edge 351 : Ag layer

A1 to A3: Thermal print head 1 : Substrate 2 : Glaze layer 3 : Electrode layer 3a : First layer 3b : Second layer 3c : Third layer 4 : Resistor layer 22 : Heat storage section 23 : Auxiliary section 30a : First Metal film 30b : Second metal film 31a : Edge 31b : Lower layer 32b : Upper layer 33 : Common electrode 34 : Common electrode strip 35 : Common electrode connecting portion 35b : Metal film 36 : Individual electrode 37 : Individual electrode connecting portion 38 : Individual electrode strip portion 39 : Bonding portion 41 : Heat generating portion 55 : Protective layer 61 : Wire 71 : Driving IC
72: sealing resin 73: connector 74: wiring board 75: heat dissipation member 301a: edge 310b: lower layer metal film 311b: lower layer covering portion 320b: upper layer metal film 321b: upper layer covering portion 322b: sedimentation portion 351: Ag layer

Claims (24)

a substrate;
an electrode layer;
A thermal printhead comprising a resistor layer including a plurality of heat generating portions arranged in the main scanning direction,
The electrode layer has a first layer interposed between the resistor layer and the substrate, and a second layer separated from the resistor layer and electrically connected to the first layer,
the first layer comprises a first metal and glass;
The second layer includes a lower layer containing a second metal and glass and having a lower layer covering portion covering the first layer, and an upper layer containing the second metal and glass and not in contact with the first layer and covering the lower layer. an upper layer having a covering,
The thermal printhead, wherein the lower layer has a lower glass content than the upper layer. 2. The thermal printhead of claim 1, wherein the lower layer of glass has a smaller grain size than the upper layer of glass. 3. A thermal printhead according to claim 2, wherein said second metal in said lower layer has a smaller grain size than said second metal in said upper layer. 4. A thermal printhead according to claim 1, wherein said first metal has a smaller degree of diffusion into said resistor layer than said second metal. 5. A thermal printhead according to any one of claims 1 to 4, wherein said lower layer is thinner than said upper layer. 6. The thermal printhead of claim 5, wherein said second layer is thicker than said first layer. 7. The thermal printhead of claim 6, wherein said lower layer is thicker than said first layer. 8. A thermal printhead according to any one of claims 1 to 7, wherein said first metal is Au. 9. A thermal printhead according to any one of claims 1 to 8, wherein said second metal is Ag. 10. The thermal printhead of any one of claims 1-9, wherein the resistor layer comprises ruthenium oxide. 11. The thermal printhead according to any one of claims 1 to 10, wherein said lower layer covering portion is exposed from said upper layer. 12. The thermal printhead according to claim 11, wherein the upper layer covering portion overlaps with the first layer in plan view. 13. A thermal printhead according to any preceding claim, comprising a glaze layer formed on the substrate. 14. The thermal printhead of claim 13, wherein the glaze layer is made of glass. 15. A thermal printhead according to claim 1, wherein said substrate is made of ceramics. 16. The thermal printhead of claim 15, wherein the substrate is made of AlN. The electrode layer includes a common electrode having a common electrode connection portion extending in the main scanning direction and a plurality of common electrode strip portions extending in the sub-scanning direction from the common electrode connection portion; 13. The thermal printhead according to any one of claims 1 to 12, comprising a plurality of individual electrodes each having an individual electrode strip positioned between said common electrode strips adjacent in the scanning direction. . 18. The thermal printhead of claim 17, wherein the resistor layer intersects the plurality of common electrode strips and the plurality of individual electrode strips. 19. The thermal printhead of claim 18, wherein the plurality of common electrode strips and the plurality of individual electrode strips are interposed between the substrate and the resistor layer. 20. The thermal printhead of claim 19, wherein the plurality of common electrode strips and the plurality of individual electrode strips are configured by the first layer. The individual electrode has an individual electrode connecting portion that is connected to the individual electrode strip portion on the side opposite to the resistor layer in the sub-scanning direction,
21. A thermal printhead according to claim 20, wherein said individual electrode connecting portion comprises said first layer and said second layer. 22. A thermal printhead according to claim 21, wherein the width of said lower layer covering portion exposed from said upper layer in said individual electrode connecting portion is smaller than the width of said upper layer. 23. A thermal printhead according to any preceding claim, comprising a protective layer covering said resistor layer. 24. The thermal printhead of Claim 23, wherein the protective layer is made of glass .

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