JP2024019972A - Insulating substrate, manufacturing method of insulating substrate, and thermal print head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulating substrate which is capable of reducing an interval between bonding pads of individual electrodes adjacent to each other when used for manufacturing a thermal print head.

SOLUTION: An insulating substrate 100 comprises: a ceramic layer 10 with a main surface 10a; a protrusion part 20 which is arranged on the main surface 10a, and extends linearly along a first direction DR1 in plan view; and a glaze layer 30 arranged on the main surface 10a so as to cover the protrusion part 20. A top face 21 of the protrusion part 20 is flat. A melting point of a constituent material of the protrusion part 20 is higher than a burning temperature of the glaze layer 30.

SELECTED DRAWING: Figure 2

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present disclosure relates to an insulating substrate, a method for manufacturing the insulating substrate, and a thermal print head.

For example, Japanese Patent Laid-Open No. 2022-78589 (Patent Document 1) describes a thermal print head. The thermal print head described in Patent Document 1 uses an insulating substrate. The insulating substrate has a ceramic layer, a glaze layer, and a metal layer. A glaze layer is disposed on the main surface of the ceramic layer. A metal layer is disposed on the glaze layer. The metal layer becomes a common electrode and a plurality of individual electrodes of the thermal print head described in Patent Document 1 by being patterned.

Japanese Patent Application Publication No. 2022-78589

Each of the plurality of individual electrodes has a bonding pad. Two adjacent bonding pads are defined as a first bonding pad and a second bonding pad, respectively. Wire bonding is performed on the first bonding pad and the second bonding pad for connection to the driver IC.

When the distance between the first bonding pad and the second bonding pad becomes short, the bonding wire connected to the first bonding pad and the bonding wire connected to the second bonding pad may interfere with each other. Therefore, it is difficult to reduce the distance between the first bonding pad and the second bonding pad.

The present disclosure has been made in view of the above problems. More specifically, the present invention provides an insulating substrate that can reduce the distance between bonding pads of adjacent individual electrodes when used for manufacturing a thermal print head.

An insulating substrate of the present disclosure includes a ceramic layer having a main surface, a raised portion disposed on the main surface and extending linearly in a first direction in a plan view, and covering the raised portion. and a glaze layer disposed on the main surface. The top surface of the ridge is flat. The melting point of the constituent material of the raised portion is higher than the firing temperature of the glaze layer.

According to the insulating substrate of the present disclosure, when used for manufacturing a thermal print head, it is possible to reduce the distance between bonding pads of adjacent individual electrodes.

1 is a plan view of an insulating substrate 100. FIG. 2 is a sectional view taken along line II-II in FIG. 1. FIG. 3 is a manufacturing process diagram of the insulating substrate 100. FIG. FIG. 3 is a cross-sectional view of an insulating substrate 100 according to a modification. 2 is a plan view of a thermal print head 200. FIG. 6 is a sectional view taken along VI-VI in FIG. 5. FIG. 6 is a sectional view taken along VII-VII in FIG. 5. FIG. FIG. 3 is a plan view of a thermal print head 200 according to a modified example. 9 is a sectional view taken along line IX-IX in FIG. 8. FIG. FIG. 2 is a process diagram showing a method for manufacturing a thermal print head 200. FIG. 3 is a cross-sectional view of the thermal print head 200 with a bonding wire 80 connected thereto. FIG. FIG. 7 is a cross-sectional view of a thermal print head 200 according to a modified example in a state where a bonding wire 80 is connected.

Details of embodiments of the present disclosure will be described with reference to the drawings. In the following drawings, the same reference numerals are given to the same or corresponding parts, and overlapping descriptions will not be repeated. The insulating substrate according to the embodiment will be referred to as an insulating substrate 100, and the thermal print head according to the embodiment will be referred to as a thermal print head 200.

(Configuration of insulating substrate 100)
The configuration of the insulating substrate 100 will be explained below.

FIG. 1 is a plan view of the insulating substrate 100. FIG. 2 is a sectional view taken along line II-II in FIG. As shown in FIGS. 1 and 2, the insulating substrate 100 includes a ceramic layer 10, a raised portion 20, a glaze layer 30, and a metal layer 40.

Ceramic layer 10 has main surface 10a and main surface 10b. The main surface 10a and the main surface 10b are end surfaces of the ceramic layer 10 in the thickness direction. Main surface 10b is the opposite surface to main surface 10a. The ceramic layer 10 has, for example, a rectangular shape in plan view. Planar view refers to the case viewed from the main surface 10a side along the normal direction of the main surface 10a. The longitudinal direction of the ceramic layer 10 in plan view is defined as a first direction DR1. A direction perpendicular to the first direction DR1 in plan view is referred to as a second direction DR2.

The ceramic layer 10 is made of, for example, a material whose main component is ceramic such as alumina (Al ₂ O ₃ ). The phrase "made of a material containing ceramic as a main component" means that the content of ceramic in the constituent material of the ceramic layer 10 is more than 50% by mass. Note that the content of ceramic in the constituent material of the ceramic layer 10 may be 70% by mass or more, or may be 80% by mass or more.

The raised portion 20 is arranged on the main surface 10a. The raised portion 20 extends linearly in a plan view. The raised portion 20 extends, for example, along the first direction DR1. The number of raised portions 20 may be plural. The plurality of raised portions 20 are lined up at intervals in the second direction DR2 in plan view. The distance between two adjacent protuberances 20 is, for example, constant.

The raised portion 20 is made of, for example, a ceramic material. The melting point of the ceramic material forming the raised portions 20 is higher than the firing temperature of the glaze layer 30. More specifically, the melting point of the ceramic material forming the raised portion 20 is higher than, for example, 1250°C. A specific example of the ceramic material forming the raised portion 20 is alumina. The constituent material of the raised portion 20 is not limited to ceramic material. The raised portion 20 may be formed of a metal material. The melting point of the ceramic material forming the raised portion 20 is higher than the firing temperature of the glaze layer 30 (higher than 1250° C.).

The raised portion 20 has a top surface 21 . The top surface 21 is flat. However, the top surface 21 does not need to be a perfect plane. The top surface 21 only needs to be flat enough to allow wire bonding to the bonding pad 52b arranged on the top surface 21 with the glaze layer 30 interposed therebetween. The width of the raised portion 20 in the second direction DR2 is defined as a width W. The width W is, for example, 100 μm or more. Let the height of the raised portion 20 be a height H. The height H is the maximum value of the distance between the main surface 10a and the top surface 21. The height H is, for example, 10 μm or more.

The glaze layer 30 is arranged on the main surface 10a so as to cover the raised portion 20. The glaze layer 30 is made of, for example, a material whose main component is glass. The phrase "made of a material containing glass as a main component" means that the content of glass in the constituent material of the glaze layer 30 is more than 50% by mass. Note that the content of glass in the constituent material of the glaze layer 30 may be 70% by mass or more, or may be 80% by mass or more.

Metal layer 40 is disposed on glaze layer 30. The metal layer 40 is made of a metal material. The metal layer 40 is made of, for example, gold (Au). Although not shown, the metal layer 40 may be composed of multiple layers.

(Method for manufacturing insulating substrate 100)
A method for manufacturing the insulating substrate 100 will be described below.

FIG. 3 is a manufacturing process diagram of the insulating substrate 100. As shown in FIG. 3, the method for manufacturing the insulating substrate 100 includes a preparation step S1, a raised portion forming step S2, a glaze layer forming step S3, and a metal layer forming step S4. In the preparation step S1, the ceramic layer 10 is prepared. In the ceramic layer 10 prepared in the preparation step S1, the raised portions 20, the glaze layer 30, and the metal layer 40 are not formed.

The protuberance forming step S2 is performed after the preparatory step S1. In the raised portion forming step S2, raised portions 20 are formed. For example, a 3D printer is used to form the raised portion 20. The 3D printer used to form the raised portion 20 is, for example, an FDM (Fused Deposition Modeling) type 3D printer. In forming the raised portions 20, first, a paste containing a binder and a powder of the constituent material of the raised portions 20 mixed in the binder is printed on the main surface 10a.

Second, the binder in the paste printed on the main surface 10a is removed. Thirdly, by heating the paste after the binder has been removed in a furnace, the powder of the constituent material of the raised portions 20 is sintered to form the raised portions 20 . The 3D printer used to form the raised portion 20 may be a pellet type 3D printer. Note that a dispenser may be used instead of a 3D printer to print the paste containing the constituent material of the raised portions 20.

The glaze layer forming step S3 is performed after the raised portion forming step S2. In the glaze layer forming step S3, the glaze layer 30 is formed on the main surface 10a so as to cover the raised portion 20. In forming the glaze layer 30, first, a paste containing glass is applied onto the main surface 10a so as to cover the raised portions 20. Second, the paste applied onto the main surface 10a is fired. As a result, the glaze layer 30 is formed by evaporating the solvent in the paste and bonding the glasses in the paste to each other. Note that since the melting point of the constituent material of the raised portions 20 is higher than the firing temperature of the glaze layer 30, the raised portions 20 are not melted when the glaze layer 30 is fired.

The metal layer forming step S4 is performed after the glaze layer forming step S3. In the metal layer forming step S4, a metal layer 40 is formed on the glaze layer 30. The metal layer 40 is formed, for example, by applying a resinate paste containing the constituent material of the metal layer 40 onto the glaze layer 30 and firing the resinate paste. However, the method for forming the metal layer 40 is not limited to this. Through the above steps, the insulating substrate 100 having the structure shown in FIGS. 1 and 2 is formed.

<Modified example>
FIG. 4 is a cross-sectional view of an insulating substrate 100 according to a modification. As shown in FIG. 4, the top surface 21 has a first portion 21a and a second portion 21b. The first portion 21a and the second portion 21b are adjacent to each other in the second direction DR2. The distance between the first portion 21a and the main surface 10a is defined as a distance DIS1, and the distance between the second portion 21b and the main surface 10b is defined as a distance DIS2. Distance DIS1 is smaller than distance DIS2. To put this from another perspective, the top surface 21 has a step at the boundary between the first portion 21a and the second portion 21b.

In this example, the top surface 21 has two parts, and there is a step between the two parts. However, the top surface 21 may have three or more parts, and there may be a step between two adjacent parts of the three parts.

(Configuration of thermal print head 200)
The configuration of the thermal print head 200 will be explained below.

FIG. 5 is a plan view of the thermal print head 200. FIG. 6 is a cross-sectional view taken along VI-VI in FIG. FIG. 7 is a cross-sectional view taken along VII-VII in FIG. As shown in FIGS. 5 to 7, the thermal print head 200 includes a ceramic layer 10, a raised portion 20, a glaze layer 30, a common electrode 51, a plurality of individual electrodes 52, and a heating element 60. have.

The outer peripheral edge of the ceramic layer 10 in plan view has a first side 10c and a second side 10d. The first side 10c and the second side 10d are along the first direction DR1. In plan view, the raised portion 20 is closer to the second side 10d than the first side 10c.

Common electrode 51 is arranged on glaze layer 30 . The common electrode 51 has a main body portion 51a and a plurality of protrusions 51b. The main body portion 51a extends along the first direction DR1. In plan view, the main body portion 51a is closer to the first side 10c than the second side 10d. The protruding portion 51b protrudes in the second direction DR2 from the side of the main body portion 51a facing the second side 10d. The plurality of protrusions 51b are arranged at intervals in the first direction DR1. The common electrode 51 is made of a metal material. The common electrode 51 is made of, for example, gold.

Individual electrodes 52 are arranged on glaze layer 30. Each of the plurality of individual electrodes 52 is arranged so as to be spaced apart from each other. The individual electrode 52 has a tip 52a at one end and a bonding pad 52b at the other end. The tip portion 52a is arranged between two adjacent protrusions 51b in the first direction DR1. That is, the protruding portions 51b and the tip portions 52a are arranged alternately in the first direction DR1. A driver IC 70 (see FIG. 11) is electrically connected to the bonding pad 52b. The individual electrodes 52 are made of the same material as the common electrode 51.

Two bonding pads 52b adjacent in the first direction DR1 are referred to as a bonding pad 52ba and a bonding pad 52bb, respectively. Bonding pad 52ba is arranged on top surface 21 with glaze layer 30 interposed therebetween. The bonding pad 52bb is arranged on a portion of the main surface 10a adjacent to the raised portion 20 from the second side 10d side with the glaze layer 30 interposed therebetween.

The heating element 60 extends in the first direction DR1. The heating element 60 has a portion disposed on the glaze layer 30, a portion disposed on the protrusion 51b, and a portion disposed on the tip portion 52a. These parts are continuous with each other. Thereby, the heating element 60 electrically connects the protruding portion 51b and the tip portion 52a. The heating element 60 includes glass and a plurality of conductive particles mixed in the glass. The conductive particles are made of, for example, ruthenium oxide (RuO ₂ ). A voltage is selectively applied to the individual electrodes 52 by the driver IC 70 . As a result, current flows through the portion of the heating element 60 that electrically connects the tip portion 52a of the individual electrode 52 to which the voltage is applied and the protrusion portion 51b adjacent thereto, and this portion generates resistance heat.

Although not shown, a first wiring is arranged on the glaze layer 30. The first wiring is made of silver (Ag), for example, and is electrically connected to the common electrode 51 (main body portion 51a). Further, although not shown, a second wiring is arranged on the first wiring. The second wiring is made of silver, for example. Furthermore, although not shown, the thermal print head 200 includes a protective glass that covers the common electrode 51, the individual electrodes 52, the heating element 60, the first wiring, and the second wiring. Note that the bonding pad 52b is exposed from the protective glass.

<Modified example>
FIG. 8 is a plan view of a thermal print head 200 according to a modification. FIG. 9 is a sectional view taken along line IX-IX in FIG. The three adjacent bonding pads 52b are referred to as a bonding pad 52bc, a bonding pad 52bd, and a bonding pad 52be, respectively. As shown in FIGS. 8 and 9, in the first direction DR1, the bonding pad 52bd is between the bonding pad 52bc and the bonding pad 52be.

The bonding pad 52bc is arranged on a portion of the main surface 10a adjacent to the raised portion 20 from the second side 10d side with the glaze layer 30 interposed therebetween. Bonding pad 52bd is arranged on first portion 21a with glaze layer 30 interposed therebetween. Bonding pad 52be is arranged on second portion 21b with glaze layer 30 interposed therebetween. Note that the first portion 21a is adjacent to the second portion 21b from the second side 10d side.

(Method for manufacturing thermal print head 200)
FIG. 10 is a process diagram showing a method for manufacturing the thermal print head 200. As shown in FIG. 10, the method for manufacturing the thermal print head 200 includes a preparation step S5, a wiring patterning step S6, a first wiring forming step S7, a heating element forming step S8, and a second wiring forming step S9. , a protective glass forming step S10, and a singulation step S11.

In the preparation step S5, the insulating substrate 100 is prepared. The wiring patterning step S6 is performed after the preparation step S5. In the wiring patterning step S6, the metal layer 40 is patterned to form a common electrode 51 and a plurality of individual electrodes 52. In the wiring patterning step S6, first, a photoresist is applied on the metal layer 40. The photoresist is applied using a roll coater, for example. Second, the photoresist coated on metal layer 40 is exposed. Exposure is performed, for example, by partially irradiating the photoresist with UV (Ultra Violet) light using a glass mask. The portions of the photoresist that are irradiated with UV light are altered in quality. Third, a resist pattern is formed by dissolving and removing portions of the photoresist that have been altered in quality by exposure. Fourth, by etching the metal layer 40 using the resist pattern as a mask, a common electrode 51 and a plurality of individual electrodes 52 are formed. Note that the resist pattern is dissolved and removed after the metal layer 40 is etched.

The first wiring forming step S7 is performed after the wiring patterning step S6. In the first wiring formation step S7, a first wiring is formed. The first wiring is formed by applying a conductive paste containing a plurality of silver particles and firing the applied conductive paste.

The heating element forming step S8 is performed after the first wiring forming step S7. In the heating element forming step S8, the heating element 60 is formed. The heating element 60 is formed by applying a conductive paste containing glass and a plurality of ruthenium oxide particles and firing the applied conductive paste. The second wiring forming step S9 is performed after the heating element forming step S8. In the second wiring formation step S9, a second wiring is formed. The second wiring is formed by applying a conductive paste containing a plurality of silver particles and firing the applied conductive paste.

The protective glass forming step S10 is performed after the second wiring forming step S9. In the protective glass forming step S10, a protective glass is formed. The protective glass is formed by applying a glass paste to cover the common electrode 51, the plurality of individual electrodes 52, the first wiring, the heating element 60, and the second wiring, and firing the applied glass paste. . The singulation step S11 is performed after the protective glass forming step S10. In the singulation step S11, a plurality of thermal print heads 200 are obtained, for example, by irradiating a laser along the boundary between two adjacent thermal print heads 200.

(Effects of insulating substrate 100 and thermal print head 200)
The effects of the insulating substrate 100 and the thermal print head 200 will be explained below.

FIG. 11 is a cross-sectional view of the thermal print head 200 with the bonding wire 80 connected. As shown in FIG. 11, the driver IC 70 has a plurality of bonding pads 71.

One end of the bonding wire 80 is bonded to the bonding pad 71. The other end of the bonding wire 80 is bonded to the bonding pad 52b. The bonding between one end of the bonding wire 80 and the bonding pad 71 is, for example, ball bonding, and the bonding between the other end of the bonding wire 80 and the bonding pad 52b is, for example, wedge bonding.

The thermal print head 200 is formed using an insulating substrate 100 having a raised portion 20. Therefore, in the thermal print head 200, the bonding pad 52ba is arranged on the top surface 21 with the glaze layer 30 interposed therebetween, and the bonding pad 52bb is arranged on the part of the main surface 10a adjacent to the raised part 20 with the glaze layer 30 interposed therebetween. will be placed in That is, in the thermal print head 200, the height position of the bonding pad 52ba and the height position of the bonding pad 52bb can be made different.

As a result, according to the thermal print head 200, even if the distance between the bonding pads 52ba and 52bb in the first direction DR1 is reduced, the bonding wire 80 bonded to the bonding pad 52ba is not bonded to the bonding pad 52bb. Interference with the bonding wire 80 is suppressed.

Further, if the thermal print head 200 does not have the raised portion 20, that is, if the height position of the bonding pad 52ba and the height position of the bonding pad 52bb do not differ, the bonding pad 52ba and the bonding pad 52bb in the second direction DR2 It is necessary to increase the distance between That is, in this case, it is necessary to lengthen the bonding wire 80 connected to the bonding pad 52ba. However, in the thermal print head 200, since the height position of the bonding pad 52ba and the height position of the bonding pad 52bb are different due to the raised portion 20, the bonding wire connected to the bonding pad 52ba is different from the height position of the bonding pad 52ba compared to the above case. 80 can be made shorter.

FIG. 12 is a cross-sectional view of a thermal print head 200 according to a modified example with bonding wires 80 connected. As shown in FIG. 12, in the thermal print head 200 according to the modification, the height position of the bonding pad 52bc and the height position of the bonding pad 52bd are different, and the height position of the bonding pad 52bd and the bonding pad 52be is different. The location is different. Therefore, in the thermal print head 200 according to the modification, even if the distance between the bonding pad 52bc and the bonding pad 52bd and the distance between the bonding pad 52bd and the bonding pad 52be are reduced, the bonding wire bonded to the bonding pad 52bc 80 and the bonding wire 80 bonded to the bonding pad 52bd, and interference between the bonding wire 80 bonded to the bonding pad 52bd and the bonding wire 80 bonded to the bonding pad 52be can be suppressed. Further, in this case, the bonding wire 80 bonded to the bonding pad 52bd and the bonding wire 80 bonded to the bonding pad 52be can be shortened.

Note that since the ceramic layer 10 is difficult to process, it is difficult to form a structure corresponding to the raised portion 20 by processing the ceramic layer 10. Further, when attempting to process the glaze layer 30 to form a structure corresponding to the raised portion 20, it is necessary to form the glaze layer 30 thickly and also to perform etching on the glaze layer 30, which increases manufacturing costs. . In this case, it is also necessary to use highly toxic chemicals such as hydrofluoric acid for the above etching. On the other hand, in the insulating substrate 100, the raised portions 20 are formed using a 3D printer or a dispenser, so an increase in manufacturing costs can be suppressed and the use of highly toxic chemicals can be avoided.

(Additional note)
Below, configurations according to embodiments of the present disclosure will be additionally described.

<Additional note 1>
a ceramic layer having a main surface;
a raised portion disposed on the main surface and extending linearly along the first direction in plan view;
a glaze layer disposed on the main surface so as to cover the raised portion,
The top surface of the raised portion is flat,
The insulating substrate may have a melting point of a constituent material of the raised portions higher than a firing temperature of the glaze layer.

<Additional note 2>
The insulating substrate according to supplementary note 1, wherein the constituent material is a ceramic material.

<Additional note 3>
The width of the raised portion in the second direction is 100 μm or more,
The insulating substrate according to appendix 1 or 2, wherein the second direction is orthogonal to the first direction in plan view.

<Additional note 4>
The insulating substrate according to any one of Supplementary Notes 1 to 3, wherein the height of the raised portion is 10 μm or more.

<Additional note 5>
The insulating substrate according to any one of Supplementary Notes 1 to 4, wherein the melting point is higher than 1250°C.

<Additional note 6>
preparing a ceramic layer having a major surface;
forming a raised portion on the main surface so as to extend linearly in plan view;
forming a glaze layer on the main surface so as to cover the raised portion,
The raised portion is formed using a 3D printer or a dispenser,
The top surface of the raised portion is flat,
The method for manufacturing an insulating substrate, wherein the melting point of the constituent material of the raised portion is higher than the firing temperature of the glaze layer.

<Additional note 7>
a ceramic layer having a main surface;
a raised portion disposed on the main surface and extending linearly along the first direction in plan view;
a glaze layer disposed on the main surface so as to cover the raised portion;
a common electrode disposed on the glaze layer;
a first individual electrode and a second individual electrode disposed on the glaze layer;
comprising a heating element electrically connecting the first individual electrode, the second individual electrode, and the common electrode,
The top surface of the raised portion is flat,
The melting point of the constituent material of the raised portion is higher than the firing temperature of the glaze layer,
The first individual electrode has a first bonding pad disposed on the top surface with the glaze layer interposed therebetween;
The second individual electrode has a second bonding pad disposed on a portion of the main surface adjacent to the raised portion with the glaze layer interposed therebetween;
The first bonding pad and the second bonding pad are arranged next to each other in the first direction.

<Additional note 8>
driver IC and
further comprising a first bonding wire and a second bonding wire,
The driver IC has a third bonding pad and a fourth bonding pad,
One end of the first bonding wire and one end of the second bonding wire are ball-bonded to the third bonding pad and the fourth bonding pad, respectively,
The thermal print head according to appendix 7, wherein the other end of the first bonding wire and the other end of the second bonding wire are wedge-bonded to the first bonding pad and the second bonding pad, respectively.

Although the embodiments of the present disclosure have been described above, the embodiments described above can be modified in various ways. Moreover, the scope of the present invention is not limited to the above-described embodiments. The scope of the present invention is indicated by the claims, and is intended to include all changes within the meaning and scope equivalent to the claims.

Reference Signs List 10 ceramic layer, 10a, 10b main surface, 10c first side, 10d second side, 20 raised portion, 21 top surface, 21a first portion, 21b second portion, 30 glaze layer, 40 metal layer, 51 common electrode, 51a main body, 51b protrusion, 52 individual electrode, 52a tip, 52b, 52ba, 52bb, 52bc, 52bd, 52be bonding pad, 60 heating element, 70 driver IC, 71 bonding pad, 80 bonding wire, 100 insulating substrate, 200 Thermal print head, DIS1, DIS2 distance, DR1 first direction, DR2 second direction, H height, S1 preparation process, S2 ridge formation process, S3 glaze layer formation process, S4 metal layer formation process, S5 preparation process, S6 wiring patterning process, S7 first wiring forming process, S8 heating element forming process, S9 second wiring forming process, S10 protective glass forming process, S11 singulation process, W width.

Claims (8)

a ceramic layer having a main surface;
a raised portion disposed on the main surface and extending linearly along the first direction in plan view;
a glaze layer disposed on the main surface so as to cover the raised portion,
The top surface of the raised portion is flat,
The insulating substrate may have a melting point of a constituent material of the raised portions higher than a firing temperature of the glaze layer. The insulating substrate according to claim 1, wherein the constituent material is a ceramic material. The width of the raised portion in the second direction is 100 μm or more,
The insulating substrate according to claim 1, wherein the second direction is orthogonal to the first direction in plan view. The insulating substrate according to claim 1, wherein the height of the raised portion is 10 μm or more. The insulating substrate according to any one of claims 1 to 4, wherein the melting point is higher than 1250°C. preparing a ceramic layer having a major surface;
forming a raised portion on the main surface so as to extend linearly in plan view;
forming a glaze layer on the main surface so as to cover the raised portion,
The raised portion is formed using a 3D printer or a dispenser,
The top surface of the raised portion is flat,
The method for manufacturing an insulating substrate, wherein the melting point of the constituent material of the raised portion is higher than the firing temperature of the glaze layer. a ceramic layer having a main surface;
a raised portion disposed on the main surface and extending linearly along the first direction in plan view;
a glaze layer disposed on the main surface so as to cover the raised portion;
a common electrode disposed on the glaze layer;
a first individual electrode and a second individual electrode disposed on the glaze layer;
comprising a heating element electrically connecting the first individual electrode, the second individual electrode, and the common electrode,
The top surface of the raised portion is flat,
The melting point of the constituent material of the raised portion is higher than the firing temperature of the glaze layer,
The first individual electrode has a first bonding pad disposed on the top surface with the glaze layer interposed therebetween;
The second individual electrode has a second bonding pad disposed on a portion of the main surface adjacent to the raised portion with the glaze layer interposed therebetween;
The first bonding pad and the second bonding pad are arranged next to each other in the first direction. driver IC and
further comprising a first bonding wire and a second bonding wire,
The driver IC has a third bonding pad and a fourth bonding pad,
One end of the first bonding wire and one end of the second bonding wire are ball-bonded to the third bonding pad and the fourth bonding pad, respectively,
The thermal print head according to claim 7, wherein the other end of the first bonding wire and the other end of the second bonding wire are wedge-bonded to the first bonding pad and the second bonding pad, respectively.

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