JP2023121322A - Thermal print head, method for manufacturing thermal print head, and thermal printer - Google Patents

Abstract

To provide a thermal print head which is suitable for preventing improper short circuit caused by a wiring layer containing silver.SOLUTION: A thermal print head A1 includes a substrate 1 having a main surface 11 facing a z direction (thickness direction), a glaze layer 2 arranged on the main surface 11, a resistor layer which is arranged on the glaze layer 2 and includes a plurality of heat generation parts arrayed in a main scanning direction, a wiring layer 3 which is arranged on the glaze layer 2 and conducts with the resistor layer, and a protective layer 5 which is arranged on the glaze layer 2 and covers at least the plurality of heat generation parts, wherein the wiring layer 3 has a first layer 31 stacked on the glaze layer 2, and a second layer 32 which is stacked on a part of the first layer 31 and is not covered with the protective layer 5, a component of the first layer 31 contains silver, and a component of the second layer 32 contains a metal element other than the silver.SELECTED DRAWING: Figure 5

Description

The present disclosure relates to thermal printheads, methods of manufacturing thermal printheads, and thermal printers.

Patent Document 1 discloses an example of a conventional thermal printhead. The thermal printhead disclosed in the document comprises a substrate, a glaze layer, an electrode layer, a resistor layer, a protective layer and a drive IC. The substrate is a plate-like member made of an insulating material, such as ceramic such as alumina (Al ₂ O ₃ ). 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 resistor layer has a plurality of heat generating portions arranged in the main scanning direction. The drive IC controls the current that flows to each heat generating portion.

In the thermal printhead disclosed in Patent Document 1, the protective layer covers most of the resistor layer and the electrode layer. On the other hand, the protective layer is not formed in the region of the electrode layer that includes the bonding portion for connecting to the driving IC, and a part of the electrode layer is exposed from the protective layer. When silver (Ag) is used as the constituent material of the electrode layer, the resistance value can be reduced. However, in the portion of the electrode layer exposed from the protective layer, ion migration may occur to cause an unintended short circuit when a voltage is applied in a use environment with high moisture (humidity).

JP 2019-147300 A

The present disclosure has been conceived under the circumstances described above, and a main object of the present disclosure is to provide a thermal printhead suitable for preventing undue short circuits caused by wiring layers containing silver. .

A thermal printhead provided by the first aspect of the present disclosure includes a substrate having a major surface facing one side in a thickness direction, a glaze layer disposed on the major surface, and a glaze layer on the glaze layer. a resistor layer disposed on the glaze layer and including a plurality of heat generating portions arranged in the main scanning direction; a wiring layer disposed on the glaze layer and electrically connected to the resistor layer; and a protective layer covering at least the plurality of heat-generating portions, wherein the wiring layer comprises a first layer laminated on the glaze layer, and a part of the first layer laminated on the wiring layer, and the protective layer and a second layer that is not covered with silver, the constituent material of the first layer contains silver, and the constituent material of the second layer contains a metal element other than silver.

A method of manufacturing a thermal printhead provided by a second aspect of the present disclosure includes the steps of providing a substrate; forming a glaze layer on the substrate; forming a layer; forming a resistor layer on the glaze layer; and forming a protective layer on the glaze layer to cover a portion of the first layer and the resistor layer. forming a coating layer containing a first metal that is a metal element other than silver so as to cover the protective layer and the first layer; heating the first layer and the coating layer; forming an alloy layer containing silver and the first metal at a boundary between one layer and the coating layer; and removing the coating layer.

A thermal printer provided by a third aspect of the present disclosure includes a thermal print head according to the first aspect of the present disclosure, and a platen arranged to face the plurality of heat generating portions.

Advantageous Effects of Invention According to the present disclosure, it is possible to prevent undue short circuits caused by wiring layers containing silver.

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

FIG. 1 is a plan view showing a thermal printhead according to a first embodiment of the present disclosure; FIG. FIG. 2 is a schematic cross-sectional view along line II-II of FIG. 3 is a partially enlarged plan view of the thermal print head shown in FIG. 1. FIG. 4 is a partially enlarged view of FIG. 2. FIG. 5 is a partially enlarged view of FIG. 4. FIG. 6 is a partially enlarged cross-sectional view taken along line VI-VI of FIG. 3. FIG. FIG. 7 is a cross-sectional view similar to FIG. 5 showing a thermal printhead according to a second embodiment of the present disclosure; FIG. 8 is a cross-sectional view similar to FIG. 6 showing a thermal printhead according to a second embodiment of the present disclosure; It is a sectional view. FIG. 9 is a cross-sectional view showing one step of an example of a method of manufacturing the thermal print head shown in FIG. FIG. 10 is a cross-sectional view showing a step following FIG. 11 is a cross-sectional view showing a step following FIG. 10. FIG. FIG. 12 is a cross-sectional view showing a step following FIG. 11. FIG. FIG. 13 is a cross-sectional view showing a step following FIG. 12. FIG. FIG. 14 is a cross-sectional view showing a step following FIG. 13. FIG. 15 is a cross-sectional view showing a step following FIG. 14. FIG. FIG. 16 is a cross-sectional view similar to FIG. 5 showing a thermal printhead according to a third embodiment of the present disclosure; FIG. 17 is a cross-sectional view similar to FIG. 6 showing a thermal printhead according to a third embodiment of the present disclosure;

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

The terms "first", "second", etc. in this disclosure are used merely as labels and are not necessarily intended to imply a permutation of the objects.

In the present disclosure, unless otherwise specified, the terms “a certain entity A is formed on a certain entity B” and “a certain entity A is formed on a certain entity B” mean “a certain entity A is formed on a certain entity B”. It includes "being directly formed in entity B" and "being formed in entity B while another entity is interposed between entity A and entity B". Similarly, unless otherwise specified, ``an entity A is placed on an entity B'' and ``an entity A is located on an entity B'' mean ``an entity A is located on an entity B.'' It includes "directly placed on B" and "some entity A is placed on an entity B while another entity is interposed between an entity A and an entity B." Similarly, unless otherwise specified, ``an object A is located on an object B'' means ``an object A is adjacent to an object B and an object A is positioned on an object B. and "the thing A is positioned on the thing B while another thing is interposed between the thing A and the thing B". In addition, unless otherwise specified, ``an object A overlaps an object B when viewed in a certain direction'' means ``an object A overlaps all of an object B'' and ``an object A overlaps an object B.'' It includes "overlapping a part of a certain thing B".

<First embodiment>
1-6 show a thermal printhead according to a first embodiment of the present disclosure. A thermal printhead A1 of this embodiment includes a substrate 1, a glaze layer 2, a wiring layer 3, a resistor layer 4, a protective layer 5, a plurality of wires 61, a drive IC 71, a protective resin 72 and a connector 73. FIG. The thermal print head A1 is incorporated in a printer that prints on a print medium 82 conveyed by a platen roller 81 (see FIG. 2). Such print media 82 include, for example, thermal paper for creating barcode sheets and receipts. A thermal printer of the present disclosure comprises a thermal print head of the present disclosure and a platen roller.

FIG. 1 is a plan view showing the thermal print head A1. FIG. 2 is a schematic cross-sectional view along line II-II of FIG. FIG. 3 is a partially enlarged plan view showing the thermal print head A1. FIG. 4 is a sectional view enlarging a part of FIG. FIG. 5 is a cross-sectional view enlarging a part of FIG. 6 is a partially enlarged cross-sectional view taken along line VI-VI of FIG. 3. FIG. For convenience of understanding, the protective layer 5 is omitted in FIGS. 1 and 3. FIG. In FIG. 3, the boundary of the formation area of the protective layer 5 is indicated by imaginary lines. In FIG. 4, the connector 73 is omitted. In FIG. 5, the protective resin 72 is transparent and is indicated by imaginary lines. In these figures, the longitudinal direction (main scanning direction) of the substrate 1 is defined as the x direction, the lateral direction (sub-scanning direction) is defined as the y direction, and the thickness direction is defined as the z direction. 1 and 3 (left side in FIGS. 2 and 4) is defined as "upstream" where the print medium is fed, and the upper side in FIGS. ) is the “downstream” where the print medium is ejected. As for the z direction, the upward direction in FIGS. 2 and 4 (the direction indicated by the arrow indicating the direction z) is defined as "upward", and the opposite direction is defined as "downward". The same applies to the following figures.

The substrate 1 is made of ceramic such as Al ₂ O ₃ and has a thickness of about 0.5 to 1.5 mm. As shown in FIG. 1, the substrate 1 has a long rectangular shape extending in the x direction. Substrate 1 has a main surface 11 . The main surface 11 faces upward (one side in the z direction). Glaze layer 2 , wiring layer 3 , resistor layer 4 , protective layer 5 , drive IC 71 and protective resin 72 are each arranged on main surface 11 of substrate 1 . The connector 73 is for connecting with an external device, and is provided, for example, at the lower end of the substrate 1 in the y direction in FIG.

The glaze layer 2 is arranged on the substrate 1 and is made of a glass material such as amorphous glass. The glaze layer 2 of this embodiment is formed to have a constant thickness, and has a substantially flat main glaze surface 21 facing upward in the z-direction. The thickness of glaze layer 2 is, for example, 10 to 300 μm.

The thermal print head A1 has a so-called thick-film configuration and is manufactured using thick-film printing. The glaze layer 2 is formed by printing a thick film of glass paste on the substrate 1 and then firing it. The glaze layer 2 is formed by a thick film forming technique.

The wiring layer 3 constitutes a path for energizing the resistor layer 4 and is arranged on the main glaze surface 21 of the glaze layer 2 . The wiring layer 3 is formed to have a specific resistance value smaller than that of the resistor layer 4 . The wiring layer 3 of this embodiment has a first layer 31 and a second layer 32 laminated on the first layer 31 . The first layer 31 is made of a conductor whose main component is silver (Ag). Most of the first layer 31 is covered with the protective layer 5 .

As shown in FIGS. 3, 5 and 6, the second layer 32 is laminated on the portion of the first layer 31 that is not covered with the protective layer 5 . In this embodiment, the second layer 32 is made of a metal different from that of the first layer 31 and contains metal elements other than Ag. The second layer 32 is made of a plated layer. The constituent material of the second layer 32 includes at least one of nickel (Ni) and gold (Au). The second layer 32 is a plating layer made of Au, for example.

As shown in FIGS. 3 to 6, the wiring layer 3 has a common electrode 33, a plurality of individual electrodes 34, a plurality of signal wiring portions 37 and a plurality of pad portions .

The common electrode 33 has a common portion 331 and a plurality of common electrode strips 332 . Specifically, the common portion 331 is arranged downstream in the y direction with respect to the resistor layer 4 and extends along the x direction. The plurality of common electrode strip portions 332 each extend upstream in the y direction from the common portion 331 and are arranged at equal pitches in the x direction.

The plurality of individual electrodes 34 are for partially energizing the resistor layer 4 , and are portions having opposite polarities with respect to the common electrode 33 . The individual electrodes 34 extend from the resistor layer 4 toward the IC chip 6 . A plurality of individual electrodes 34 are arranged in the x-direction, each having an individual electrode strip portion 35 and a connecting portion 36 .

Each individual electrode strip portion 35 is a strip portion extending in the y-direction and positioned between two adjacent common electrode strip portions 332 of the common electrode 33 . The connecting portion 36 is a portion extending from the individual electrode strip portion 35 toward the drive IC 71, and most of the connecting portion 36 has a portion along the y direction and a portion inclined with respect to the y direction. The connecting portions 36 are arranged at relatively narrow intervals in the x direction on the upstream side in the y direction. The interval between the connecting portions 36 adjacent to each other on the upstream side in the y direction is, for example, approximately 100 μm or less.

A plurality of signal wiring portions 37 constitute a wiring pattern connected to the connector 73 and the driving IC 71 . Although only one signal wiring portion 37 is shown in FIG. 4 , a plurality of signal wiring portions 37 are arranged in the x direction near the drive IC 71 and each extends in the y direction. The drive IC 71 used in the thermal print head A1 usually has a rectangular planar shape (see FIG. 1). The long side of the drive IC 71 extends along the x direction (main scanning direction) in which the resistor layer 4 extends.

As shown in FIGS. 4 and 5 , the plurality of pad portions 38 are portions connected to the drive IC 71 via a plurality of wires 61 . A plurality of pad portions 38 are arranged in the x direction and the y direction. The plurality of pad portions 38 are connected to any of the y-direction upstream end portions of the plurality of connecting portions 36 (individual electrodes 34 ) or to any of the y-direction downstream end portions of the plurality of signal wiring portions 37 . A wire 61 is bonded to each of the plurality of pad portions 38 for connection with the driving IC 71 . In the present embodiment, among the plurality of pad portions 38, those connected to the connecting portions 36 adjacent in the x direction are alternately arranged in the y direction. As a result, the plurality of pad portions 38 connected to the plurality of connecting portions 36 are prevented from interfering with each other even though the width is larger than most portions of the connecting portions 36 .

In this embodiment, as shown in FIGS. 3, 5, and 6, the second layer 32 is arranged in a region including a plurality of pad portions 38. FIG. Specifically, the second layer 32 is arranged on a portion of each of the plurality of connecting portions 36 , a portion of each of the plurality of signal wiring portions 37 , and the plurality of pad portions 38 .

The second layer 32, which is a plated layer, is formed by electroless plating, for example. In forming the second layer 32 by electroless plating, the second layer 32 is formed on the entire surface of the first layer 31 exposed from the protective layer 5 . To give an example of the thicknesses of the first layer 31 and the second layer 32, the thickness t1 (see FIG. 6) of the first layer 31 is, for example, approximately 0.5 to 30 μm. The thickness t2 of the second layer 32 is, for example, approximately 0.05 to 0.2 μm, and is thinner than the thickness t1 of the first layer 31. As shown in FIG.

A part of the wiring layer 3 may be composed of a conductor containing Au as a main component. Specifically, the portions of the wiring layer 3 mainly composed of Au are, for example, the common portion 331 and the plurality of common electrode strip portions 332 of the common electrode 33, the individual electrode strip portions 35 of the plurality of individual electrodes 34, including.

The resistor layer 4 is made of, for example, ruthenium oxide having a higher resistivity than the material forming the wiring layer 3, and is formed in a strip shape extending in the x-direction. As shown in FIG. 3 , the resistor layer 4 intersects the common electrode strips 332 of the common electrode 33 and the individual electrode strips 35 of the individual electrodes 34 . 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 332 of the common electrode 33 and the individual electrode strip portions 35 of the plurality of individual electrodes 34 . A portion of the resistor layer 4 sandwiched between the common electrode strip portions 332 and the individual electrode strip portions 35 serves as a heat generating portion 41 that generates heat by being partially energized by the wiring layer 3 . One print dot is formed by the heat generated by the two heat generating portions 41 adjacent to each other with one individual electrode strip portion 35 interposed therebetween. The thickness of resistor layer 4 is, for example, about 1 to 10 μm.

The protective layer 5 is for protecting the wiring layer 3 and the resistor layer 4 . Protective layer 5 is made of, for example, amorphous glass. However, the protective layer 5 exposes a region of the wiring layer 3 that includes the plurality of pad portions 38 .

The driving IC 71 performs a function of partially heating the resistor layer 4 by selectively energizing the plurality of individual electrodes 34 . As shown in FIGS. 1 and 4, the drive IC 71 is arranged upstream in the y direction with respect to the resistor layer 4 (the plurality of heat generating portions 41). In this embodiment, a plurality of drive ICs 71 are arranged on the glaze layer 2 . The driving IC 71 is provided with a plurality of pads. As shown in FIG. 4, the pads of the drive IC 71 and the plurality of pad portions 38 are connected via a plurality of wires 61 bonded to each. The wire 61 is made of Au, for example. As shown in FIGS. 2 and 4, the driving IC 71 is covered with a protective resin 72. As shown in FIG. Protective resin 72 is made of, for example, a black soft resin. Further, the driving IC 71 and the connector 73 are connected by the plurality of signal wiring portions 37 . The drive IC 71 receives a print signal and a control signal transmitted from the outside via the connector 73 and a voltage supplied to the plurality of heat generating portions 41 . The plurality of heat generating portions 41 are selectively heated by being individually energized according to the print signal and the control signal.

Next, an example of how to use the thermal print head A1 will be briefly described.

The thermal print head A1 is used while being incorporated in the printer. As shown in FIG. 2, each heat generating portion 41 of the thermal print head A1 faces a platen roller 81 in the printer. When the printer is used, the platen roller 81 rotates to feed a printing medium 82 such as thermal paper at a constant speed between the platen roller 81 and the heat generating portions 41 along the y direction. The print medium 82 is pressed by the platen roller 81 against the portions of the protective layer 5 that cover the heat generating portions 41 . On the other hand, a potential is selectively applied to each individual electrode 34 shown in FIG. 3 by the drive IC 71 . Thereby, a voltage is applied between the common electrode 33 and each of the plurality of individual electrodes 34 . Current selectively flows through the plurality of heat generating portions 41 to generate heat. The heat generated by each heat generating portion 41 is transferred to the print medium 82 through the protective layer 5 . A plurality of dots are printed in a line area linearly extending in the x direction on the print medium 82 . Moreover, the heat generated in each heat generating portion 41 is transmitted to the glaze layer 2 and stored in the glaze layer 2 .

Next, the operation of this embodiment will be described.

The wiring layer 3 constitutes a path for energizing the resistor layer 4 and has a first layer 31 and a second layer 32 . The first layer 31 is laminated on the glaze layer 2 and contains Ag. The second layer 32 is laminated on part of the first layer 31 . More specifically, the second layer 32 is laminated on the portion of the first layer 31 that is not covered with the protective layer 5 . The second layer 32 contains a metal element other than Ag (Au in this embodiment). According to such a configuration, since the second layer 32 is laminated on the portion of the first layer 31 containing Ag that is exposed from the protective layer 5, when a voltage is applied in a use environment with a lot of moisture (humidity), Also, the occurrence of ion migration in the first layer 31 can be suppressed. As a result, it is possible to prevent undue short circuits caused by the first layer 31 (wiring layer 3) containing Ag.

The second layer 32 laminated on the first layer 31 is made of a plated layer. With such a configuration, the second layer 32 can appropriately cover the entire surface of the first layer 31 exposed from the protective layer 5 . This is more suitable for suppressing ion migration in the first layer 31 .

The thickness t1 of the first layer 31 is in the range of 0.5 to 30 μm, and the thickness t2 of the second layer 32 is thinner than the thickness t1 of the first layer 31 and is in the range of 0.05 to 0.2 μm. is. The second layer 32 is arranged in a region including a plurality of pad portions 38 in the wiring layer 3 . According to such a configuration, it is possible to cover appropriate portions of the first layer 31 with the second layer 32 while reducing the usage amount of the entire second layer 32 . Thereby, the inconvenience caused by ion migration in the first layer 31 can be efficiently improved.

<Second embodiment>
7 and 8 show a thermal printhead according to a second embodiment of the present disclosure. The basic structure of the thermal print head A2 of this embodiment is the same as that of the thermal print head A1, and detailed illustration and description thereof will be omitted. The thermal print head A2 includes a substrate 1, a glaze layer 2, a wiring layer 3, a resistor layer 4, a protective layer 5, and a plurality of wires 61, like the thermal print head A1 of the embodiment shown in FIGS. , a drive IC 71 , a protective resin 72 and a connector 73 . In the thermal print head A2 of this embodiment, the configuration of the second layer 32 in the wiring layer 3 is different from that of the thermal print head A1 of the above embodiment.

In this embodiment, the second layer 32 is an alloy layer containing silver (Ag) and a metal element (first metal) other than Ag. The first metal forming second layer 32 (alloy layer) is, for example, at least one of gold (Au), copper (Cu) and aluminum (Al). Also in this embodiment, the second layer 32 is laminated on the portion of the first layer 31 not covered with the protective layer 5, as in the above embodiment. The second layer 32 is arranged in a region including a plurality of pad portions 38 .

Next, an example of a method for manufacturing the thermal print head A2 will be described below with reference to FIGS. 9 to 15. FIG. 9 to 15 are cross-sectional views showing one step of the method of manufacturing the thermal print head A1, corresponding to the cross-section shown in FIG.

First, as shown in FIG. 9, a substrate 1 is prepared. Substrate 1 is made of ceramic such as Al ₂ O ₃ and has a predetermined thickness. Substrate 1 has a main surface 11 . The main surface 11 is substantially flat and faces upward in the z-direction.

Next, as shown in FIG. 10, the glaze layer 2 is formed. The glaze layer 2 is formed by printing a thick film of glass paste on the main surface 11 of the substrate 1 and then firing it.

Next, as shown in FIG. 11, the first layer 31 is formed. In forming the first layer 31, first, a paste containing Ag is thick-film-printed on the main glaze surface 21 of the glaze layer 2, and then fired to form a metal film. Next, the first layer 31 containing Ag is formed by subjecting the metal film to patterning using, for example, etching. Next, a resistor layer 4 is formed. The resistor layer 4 is formed by printing a thick film of a resistor paste containing a resistor such as ruthenium oxide, followed by firing (see FIGS. 3 and 4).

Next, as shown in FIG. 12, protective layer 5 is formed. The protective layer 5 is formed by, for example, applying a glass paste to the region where the protective layer 5 is to be formed by thick-film printing, and firing the paste. The protective layer 5 thus formed covers most of the first layer 31 and the resistor layer 4 .

Next, as shown in FIG. 13, a coating layer 32A is formed. The coating layer 32A is formed by, for example, applying a paste containing Au (first metal) to the protective layer 5 and the first layer 31 exposed from the protective layer 5 by thick-film printing, and firing the paste. .

The coating layer 32A may be formed by a thin film formation technique such as sputtering instead of applying the paste containing Au (first metal). Examples of the material (first metal) forming the coating layer 32A include Cu and Al in addition to Au.

Next, the first layer 31 and the covering layer 32A are heated to, for example, 400 to 700° C. for annealing. As a result, as shown in FIG. 14, the second layer 32, which is an alloy layer, is formed at the boundary between the first layer 31 and the coating layer 32A. The second layer 32 (alloy layer) contains Ag derived from the first layer 31 and Au (first metal) derived from the coating layer 32A. The second layer 32 thus formed covers the first layer 31 .

Next, as shown in FIG. 15, the coating layer 32A is removed by etching. Here, the second layer 32, which is an alloy layer, and the first layer 31 covered with the second layer 32 remain without being removed by etching. After that, the thermal print head A2 is obtained by mounting the driving IC 71, bonding the wires 61, forming the protective resin 72, attaching the connector 73, and the like.

Next, the operation of this embodiment will be described.

The wiring layer 3 constitutes a path for energizing the resistor layer 4 and has a first layer 31 and a second layer 32 . The first layer 31 is laminated on the glaze layer 2 and contains Ag. The second layer 32 is laminated on part of the first layer 31 . More specifically, the second layer 32 is laminated on the portion of the first layer 31 that is not covered with the protective layer 5 . The second layer 32 contains a metal element other than Ag (Au in this embodiment). According to such a configuration, since the second layer 32 is laminated on the portion of the first layer 31 containing Ag that is exposed from the protective layer 5, when a voltage is applied in a use environment with a lot of moisture (humidity), Also, the occurrence of ion migration in the first layer 31 can be suppressed. As a result, it is possible to prevent undue short circuits caused by the first layer 31 (wiring layer 3) containing Ag.

The second layer 32 laminated on the first layer 31 is made of an alloy layer. With such a configuration, the second layer 32 can appropriately cover the entire surface of the first layer 31 exposed from the protective layer 5 . This is more suitable for suppressing ion migration in the first layer 31 .

<Third Embodiment>
16 and 17 show a thermal printhead according to a third embodiment of the present disclosure. The basic structure of the thermal print head A3 of this embodiment is the same as that of the thermal print head A1, and detailed illustration and description thereof will be omitted. The thermal print head A3 comprises a substrate 1, a glaze layer 2, a wiring layer 3, a resistor layer 4, a protective layer 5, a plurality of wires 61, as in the thermal print head A1 of the embodiment shown in FIGS. , a drive IC 71 , a protective resin 72 and a connector 73 . The thermal print head A3 of this embodiment further includes an additional protective layer 51, and the configuration of the second layer 32 in the wiring layer 3 is different from that of the thermal print head A1 of the above embodiment.

As shown in FIG. 16, the additional protective layer 51 is arranged in areas where the protective layer 5 is not formed. An additional protective layer 51 is arranged on the glaze layer 2 (glaze main surface 21 ) and on the second layer 32 . Additional protective layer 51 is made of amorphous glass, for example.

An opening 321 and an opening 511 are formed in the second layer 32 and the additional protective layer 51 at the center (central region in the x-direction and y-direction) of each of the plurality of pad portions 38 . Apertures 511 and 321 are formed by selectively wet blasting the center of each pad portion 38 . This wet blasting process removes portions of the additional protective layer 51 and the second layer 32 to form openings 511 and 321 . The first layer 31 is exposed from the second layer 32 and the additional protective layer 51 at the portions where the openings 511 and 321 are formed. A wire 61 is bonded to the exposed first layer 31 at each pad portion 38 .

Next, the operation of this embodiment will be described.

The wiring layer 3 constitutes a path for energizing the resistor layer 4 and has a first layer 31 and a second layer 32 . The first layer 31 is laminated on the glaze layer 2 and contains Ag. The second layer 32 is laminated on part of the first layer 31 . More specifically, the second layer 32 is laminated on the portion of the first layer 31 that is not covered with the protective layer 5 . The second layer 32 contains a metal element other than Ag (Au in this embodiment). According to such a configuration, most of the portion of the first layer 31 containing Ag that is exposed from the protective layer 5 is laminated with the second layer 32, so voltage application in a use environment with a lot of moisture (humidity) is possible. Even in this case, the occurrence of ion migration in the first layer 31 can be suppressed. As a result, it is possible to prevent undue short circuits caused by the first layer 31 (wiring layer 3) containing Ag.

In this embodiment, an additional protective layer 51 is arranged in a region where the protective layer 5 is not formed. In each of the plurality of pad portions 38, openings 511 and 321 are formed in the additional protective layer 51 and the second layer 32, and the first layer 31 and the second layer 32 and It is exposed through the additional protective layer 51 . When the second layer 32 is a plated layer made of Ni, the bondability of the wire 61 to the second layer 32 is deteriorated. Even in such a case, in this embodiment, by exposing only a portion of the first layer 31 of each pad portion 38, the wire 61 can be bonded to the first layer 31, and the first layer 31 can be bonded. It is possible to suppress the occurrence of ion migration in.

Thermal printheads according to the present disclosure are not limited to the embodiments described above. The specific configuration of each part of the thermal print head according to the present disclosure can be modified in various ways.

The present disclosure includes configurations related to the following appendices.

[Appendix 1]
a substrate having a main surface facing one side in the thickness direction;
a glaze layer disposed on the main surface;
a resistor layer disposed on the glaze layer and including a plurality of heat generating portions arranged in the main scanning direction;
a wiring layer disposed on the glaze layer and conducting to the resistor layer;
a protective layer disposed on the glaze layer and covering at least the plurality of heat generating parts;
The wiring layer has a first layer laminated on the glaze layer and a second layer laminated on a part of the first layer and not covered with the protective layer,
The constituent material of the first layer contains silver,
The thermal printhead, wherein the constituent material of the second layer contains a metal element other than silver.
[Appendix 2]
The thermal printhead according to Appendix 1, wherein the second layer is a plated layer.
[Appendix 3]
The thermal printhead according to appendix 2, wherein the constituent material of the second layer includes at least one of nickel and gold.
[Appendix 4]
4. The thermal printhead of claim 2 or 3, wherein the thickness of the second layer is in the range of 0.05-0.2 μm.
[Appendix 5]
The thermal printhead according to Appendix 1, wherein the second layer is an alloy layer containing silver and a first metal other than silver.
[Appendix 6]
6. The thermal printhead according to appendix 5, wherein the first metal is at least one of gold, copper, and aluminum.
[Appendix 7]
The wiring layer has a plurality of pad portions,
7. The thermal printhead according to any one of Appendices 1 to 6, wherein the second layer is arranged in a region including the plurality of pad portions.
[Appendix 8]
8. The thermal printhead according to appendix 7, wherein the plurality of pad portions are arranged in the main scanning direction and in the sub-scanning direction.
[Appendix 9]
9. The thermal printhead according to any one of Appendices 1 to 8, wherein the thickness of the first layer is in the range of 0.5 to 30 μm.
[Appendix 10]
10. The thermal printhead according to any one of Appendices 1 to 9, further comprising a driving IC for controlling current flowing through each of the heat generating portions.
[Appendix 11]
11. The thermal printhead of Claim 10, wherein the drive IC is positioned over the glaze layer.
[Appendix 12]
12. A thermal printhead according to any one of appendices 1 to 11, wherein the substrate is made of ceramic.
[Appendix 13]
preparing a substrate;
forming a glaze layer on the substrate;
forming a first layer comprising silver on the glaze layer;
forming a resistor layer on the glaze layer;
forming a protective layer on the glaze layer to cover a portion of the first layer and the resistor layer;
forming a coating layer containing a first metal that is a metal element other than silver so as to cover the protective layer and the first layer;
a step of heating the first layer and the coating layer to form an alloy layer containing silver and the first metal at a boundary portion between the first layer and the coating layer;
and removing the coating layer.
[Appendix 14]
14. The method of manufacturing a thermal printhead according to Appendix 13, wherein the step of forming the coating layer is performed by applying a paste containing the first metal.
[Appendix 15]
14. The method of manufacturing a thermal printhead according to Appendix 13, wherein the step of forming the coating layer is performed by sputtering.
[Appendix 16]
a thermal printhead according to any one of Appendices 1 to 12;
A thermal printer, comprising: a platen roller arranged to face the plurality of heat generating portions.

A1, A2, A3: Thermal print head 1: Substrate 11: Main surface 2: Glaze layer 21: Glaze main surface 3: Wiring layer 31: First layer 32: Second layer 32A: Coating layer 321: Opening 33: Common electrode 331 : Common portion 332 : Common electrode strip portion 34 : Individual electrode 35 : Individual electrode strip portion 36 : Connection portion 37 : Signal wiring portion 38 : Pad portion 4 : Resistor layer 41 : Heat generating portion 5 : Protective layer 51 : Additional Protective layer 511 : Opening 61 : Wire 71 : Driving IC
72: protective resin 73: connector 81: platen roller 82: print medium

Claims (16)

a substrate having a main surface facing one side in the thickness direction;
a glaze layer disposed on the main surface;
a resistor layer disposed on the glaze layer and including a plurality of heat generating portions arranged in the main scanning direction;
a wiring layer disposed on the glaze layer and conducting to the resistor layer;
a protective layer disposed on the glaze layer and covering at least the plurality of heat generating parts;
The wiring layer has a first layer laminated on the glaze layer and a second layer laminated on a part of the first layer and not covered with the protective layer,
The constituent material of the first layer contains silver,
The thermal printhead, wherein the constituent material of the second layer contains a metal element other than silver. 2. The thermal printhead of claim 1, wherein the second layer is a plated layer. 3. A thermal printhead according to claim 2, wherein the constituent material of said second layer includes at least one of nickel and gold. A thermal printhead according to claim 2 or 3, wherein the thickness of said second layer ranges from 0.05 to 0.2 µm. 2. A thermal printhead according to claim 1, wherein said second layer is an alloy layer containing silver and a first metal other than silver. 6. The thermal printhead of claim 5, wherein the first metal is at least one of gold, copper, and aluminum. The wiring layer has a plurality of pad portions,
7. The thermal printhead according to any one of claims 1 to 6, wherein said second layer is arranged in a region including said plurality of pad portions. 8. The thermal printhead according to claim 7, wherein said plurality of pad portions are arranged in plurality each in the main scanning direction and the sub-scanning direction. A thermal printhead according to any preceding claim, wherein the thickness of said first layer ranges from 0.5 to 30 µm. 10. The thermal printhead according to any one of claims 1 to 9, further comprising a driving IC for controlling current flowing through each heat generating portion. 11. The thermal printhead of claim 10, wherein the drive IC is positioned over the glaze layer. 12. A thermal printhead according to any one of claims 1 to 11, wherein said substrate is made of ceramic. preparing a substrate;
forming a glaze layer on the substrate;
forming a first layer comprising silver on the glaze layer;
forming a resistor layer on the glaze layer;
forming a protective layer on the glaze layer to cover a portion of the first layer and the resistor layer;
forming a coating layer containing a first metal that is a metal element other than silver so as to cover the protective layer and the first layer;
a step of heating the first layer and the coating layer to form an alloy layer containing silver and the first metal at a boundary portion between the first layer and the coating layer;
and removing the coating layer. 14. The method of manufacturing a thermal printhead according to claim 13, wherein the step of forming the coating layer is performed by applying a paste containing the first metal. 14. The method of manufacturing a thermal printhead according to claim 13, wherein the step of forming the coating layer is performed by sputtering. a thermal print head according to any one of claims 1 to 12;
A thermal printer, comprising: a platen roller arranged to face the plurality of heat generating portions.

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