WO2006049095A1

WO2006049095A1 - Thermal print head and method for manufacturing same

Info

Publication number: WO2006049095A1
Application number: PCT/JP2005/019879
Authority: WO
Inventors: Takumi Yamade
Original assignee: Rohm Co., Ltd.
Priority date: 2004-11-04
Filing date: 2005-10-28
Publication date: 2006-05-11
Also published as: JP2006130707A; CN101052531B; EP1815996A1; TW200619045A; JP4633442B2; KR20070072568A; CN101052531A; TWI270476B; KR100910679B1

Abstract

A thermal print head (A1) is provided with a board (1), a grazed layer (2), a heat element (3), an electrode (4) having Au as a main ingredient for carrying electricity to the heat element (3), and a protection film (6) for covering the heat element (3) and the electrode (4). On the surface of the electrode (4), a plurality of recessed parts are formed.

Description

Specification

Thermal print head and manufacturing method thereof

Technical field

The present invention relates to a thermal print head used for a thermal printer. The present invention also relates to a method for manufacturing a thermal print head.

Background art

Conventionally, various thermal print heads have been proposed as apparatuses for printing on recording paper such as thermal paper (see, for example, Patent Document 1 below). FIG. 11 of the present application shows an example of a thermal print head as a related technique of the present invention. Specifically, the illustrated thermal print head B includes an insulating substrate 91 on which a glaze layer 92 made of glass, a heating resistor 93, an electrode 94, and a protective film 96 are formed. Are stacked. The protective film 96 is made of a material mainly composed of glass. During the printing process by the thermal print head B, a recording paper such as a thermal paper is moved relative to the protective film 96 in a pressure contact state. At this time, heat generated in the heating resistor 93 is transmitted to the recording paper, and desired printing is performed.

In the thermal printhead having the above-described configuration, the electrode 94 can be formed of a metal material having excellent conductivity such as Al, Cu, Au, and the like. Among these, Au is a chemically stable material and has excellent corrosion resistance. For this reason, if the electrode 94 is made of Au, it is possible to avoid poor conduction due to corrosion of the electrode. In addition, Au has lower electrical resistance (resistivity) than A1. For this reason, when the electrode 94 is made of Au, the voltage drop force is smaller than when A1 is used, and the power loss can be reduced.

[0004] By making the electrode made of Au, it is possible to obtain the advantages as described above. On the other hand, the following problems may occur. That is, Au has poor adhesion to the glass forming the protective film compared to other highly conductive metals such as A1. For this reason, the protective film may be peeled off from the electrode 94, leading to a decrease in durability of the thermal print head. In addition, a stress is generated in the protective film due to the difference in coefficient of thermal expansion between the electrode and the protective film. This stress promotes peeling of the protective film. Patent Document 1: Japanese Patent Application Laid-Open No. 2002-67367

Disclosure of the invention

[0006] The present invention has been conceived under the circumstances described above. Accordingly, an object of the present invention is to provide a thermal print head in which adhesion between an Au electrode and a protective film is enhanced. Another object of the present invention is to provide a method for manufacturing such a thermal print head.

[0007] In order to solve the above problems, the present invention takes the following technical means.

[0008] A thermal printhead provided by the first aspect of the present invention includes a substrate, a glaze layer, a heating resistor, and an electrode mainly composed of Au for energizing the heating resistor. And a protective film covering the heating resistor and the electrode. A plurality of recesses are formed on the surface of the electrode.

According to such a configuration, the adhesion between the electrode and the protective film can be increased.

Specifically, by forming a plurality of recesses on the surface of the electrode, a part of the protective film covering the electrode enters the recess. As a result, the adhesion can be improved by the so-called anchor effect. In addition, a relatively large stress can be generated in the protective film in the direction along the boundary surface due to the difference in thermal expansion coefficient between the electrode and the protective film. According to the present invention, the displacement in the direction along the boundary surface is less likely to occur, which is suitable for suppressing the peeling of the protective film from such a surface.

[0010] Preferably, the plurality of recesses are formed by setting the center line average roughness Ra of the surface of the electrode to 0.1 to 0.5 / z m. According to such a configuration, the above-described anchor effect is appropriately exhibited.

[0011] Preferably, the plurality of concave portions are formed by a plurality of through portions penetrating in the thickness direction of the electrode. The penetrating portion may be formed to have a circular cross section. In this case, the diameter of the through hole is, for example, 1 to: LO / zm. In the present invention, the through portion may be formed to have a rectangular cross section instead of a circular cross section. In this case, the rectangle has a short side and a long side, and the length of the short side (width of the rectangle) is, for example, 1 to 1 O / zm. According to such a configuration, a part of the protective film that has penetrated into the penetrating portion is in direct contact with the heating resistor that is the glaze layer formed on the lower layer side of the electrode. There is a glaze layer Since the heat generating resistor has better adhesion to the protective film than the electrode, securing the adhesion region between the protective film and the glaze layer or the heat generating resistor improves the adhesion of the protective film. Peeling can be suppressed.

[0012] Preferably, the thermal print head of the present invention further includes an insulating film formed on the lower layer side of the electrode. The insulating film has better adhesion to the protective film than the electrode. Therefore, even with such a configuration, a part of the protective film that has entered the through portion directly adheres to the insulating film, thereby improving the adhesion of the protective film and suitable for suppressing the peeling of the protective film. It is.

[0013] A thermal printhead provided by the second aspect of the present invention includes a substrate, a glaze layer, a heating resistor, and an electrode mainly composed of Au for energizing the heating resistor. And a protective film covering the heating resistor and the electrode. A metal thin film containing at least one of Ni, Cr, and Ti is formed on the electrode.

[0014] According to such a configuration, as in the first aspect of the present invention, the adhesion between the electrode and the protective film can be increased. In other words, metals such as Ni, Cr, and Ti have better adhesion to the protective film than Au. Therefore, peeling of the protective film can be suppressed by interposing the metal thin film containing the metal between the electrode and the protective film. In addition, since the above metal has excellent adhesion to Au, no defects occur when the metal thin film is peeled off from the electrode.

[0015] According to a third aspect of the present invention, a method of manufacturing a thermal print head is provided. The manufacturing method includes a step of forming a glaze layer on a substrate, a step of forming an electrode containing Au as a main component on the glaze layer, a step of forming a heating resistor, and the heating resistor and electrode. Forming a protective film covering the substrate. Further, according to the manufacturing method, the step of heat-treating the substrate is provided after the step of forming the electrode.

[0016] According to such a manufacturing method, the glass component of the glaze layer formed in the lower layer of the electrode diffuses to the vicinity of the surface of the electrode. Since glass has better adhesion to the protective film than Au, the glass component of the glaze layer that has diffused near the surface of the electrode functions as an adhesive, improving the adhesion of the protective film. As a result, the durability of the thermal print head can be improved. [0017] Preferably, the manufacturing method of the present invention further includes a step of forming a metal film including at least one of Ni, Cr, and Ti between the glaze layer and the electrode. According to this, the metal component of the metal film diffuses to the vicinity of the surface of the electrode. Since the metal has better adhesion to the protective film than Au, the metal component diffused in the vicinity of the electrode surface functions as an adhesive and improves the adhesion of the protective film.

[0018] Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

Brief Description of Drawings

FIG. 1A is a plan view schematically showing a main part of a thermal print head according to a first embodiment of the present invention, and FIG. 1B is a partial plan view showing a modified example of the common electrode. .

FIG. 2A is a cross-sectional view showing the thermal print head of the first embodiment, and FIG. 2B is a cross-sectional view schematically showing the states of the surfaces of the common electrode and the individual electrodes.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a cross-sectional view showing a modified example of the thermal print head of the first embodiment.

FIG. 5 is a plan view schematically showing a main part of a thermal print head according to a second embodiment of the present invention.

FIG. 6 is a cross-sectional view showing a thermal print head according to a second embodiment.

FIGS. 7A to 7D are cross-sectional views illustrating a method for manufacturing the thermal print head of the second embodiment.

FIGS. 8A to 8B are cross-sectional views illustrating a step that follows the step of FIG.

FIG. 9 is a cross-sectional view illustrating a step that follows the step of FIG. 8.

FIG. 10 is a cross-sectional view showing a modified example of the thermal print head of the second embodiment.

FIG. 11 is a cross-sectional view showing an example of a thermal print head as a related technique of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings.

1 to 3 show a thermal print head A1 according to a first embodiment of the present invention. Thermal print head A1 consists of substrate 1, glaze layer 2, heating resistor 3, common electrode 41, and multiple It has individual electrodes 42, a metal thin film 5, and a protective film 6 (see FIG. 2A).

[0022] The substrate 1 is a flat plate having a rectangular shape in plan view, and is made of an insulator such as alumina ceramic. On the substrate 1, a glaze layer 2, a heating resistor 3, an electrode layer 4 (each electrode 41, 42), a metal thin film 5 and a protective film 6 are laminated. The glaze layer 2 serves as a heat storage layer. Furthermore, the glaze layer 2 provides a smooth surface suitable for forming the common electrode 3 and the individual electrodes 4. According to this configuration, the common electrode 3 and the individual electrode 4 can be securely fixed on the substrate 1. The glaze layer 2 is formed by printing a glass paste and firing the paste. The glaze layer 2 includes a raised portion 21 that has an arcuate outer surface. The heating resistor 3 is made of, for example, TaSiO formed by a CVD method or a sputtering method.

2

The raised layer 21 is formed so as to cover the raised portion 21. The thickness of the heating resistor 3 is, for example, 0.2 to 2. O / zm. The electrode layer 4 is laminated on the upper layer side of the heating resistor 3, and is formed by sputtering, for example, a metal material containing Au as a main component. The thickness of the electrode layer 4 is, for example, 0.3 to 2. A part of the electrode layer 4 is selectively etched by, for example, a photolithography method, whereby the common electrode 41 and the individual electrode 42 are formed.

[0023] The common electrode 41 includes a common line portion 41A and a plurality of extending portions 41B. As shown in FIG. 1A, the common line portion 41A includes a portion (main portion) extending along the longitudinal direction of the substrate 1 and a portion (sub-portion) extending from the both end portions in the short direction of the substrate 1. . Each of the extending portions 41B protrudes from the main portion of the common line portion 41A in the short direction of the substrate 1. The common line portion 41A is a portion for allowing current to flow collectively to a heating resistor portion 31 (to be described later) with a terminal portion force outside the figure, and has a large area.

[0024] As shown in FIG. 2A, each individual electrode 42 has its one end extending to each extending portion 41B so that a part of the heating resistor 3 is exposed in the vicinity of the top surface of the raised portion 21 of the glaze layer 2. And spaced apart from each other. The other end of each individual electrode 42 is electrically connected to the driving IC 7. The driving IC 7 is for controlling energization based on image data for printing that is also transmitted with an external force, and is mounted on the substrate 1. When the drive IC 7 selectively energizes the individual electrode 42, it faces the individual electrode 42 of the heating resistor 3. The exposed portion between the extending portion 41B functions as the heat generating resistor portion 31 and is configured to form one heat generating dot.

As shown in FIG. 2B, a plurality of recesses are formed in the extended portions 41B of the common electrode and the surfaces 41Ba and 42a of the individual electrodes 42. The plurality of recesses are formed by making the surfaces 41Ba and 42a rough. Preferably, the center line average roughness Ra of the surfaces 41Ba and 42a is 0.1 to 0.5 m. Such irregularities can be formed by a surface treatment technique such as light etching.

[0026] The metal thin film 5 is laminated on the upper layer side of the common line portion 41A, and is made of Ni, Cr, or Ti.

A metal containing at least one kind is formed by a plating process or a sputtering method. The thickness of the metal thin film 5 is set to, for example, 0.2 to 2. O / z m. In the common line portion 41 A and the metal thin film 5, a plurality of through holes h having a circular shape in a plan view (circular in cross section) are formed as penetrating portions that penetrate to the lower glaze layer 2 or the heating resistor 3. The diameter of the through hole h is preferably 1 to: LO / z m. The through hole h can be formed by etching using a glass mask, for example. As shown in FIG. 1B, as the through portion, a slit S having a long rectangular cross section may be formed instead of the through hole h. Each slit S has a short side and a long side.

[0027] The protective film 6 is formed so as to cover the heating resistor 3, the common electrode 41, and the individual electrode 42. For example, a force such as SiO or SiN is also formed. The protective film 6 can be formed by CVD or spa

2

It is formed by the sputtering method. The thickness of the protective film 6 is set to, for example, 3 to: LO / z m. As clearly shown in FIGS. 2 and 3, a part of the protective film 6 enters the through hole h and is in direct contact with the glaze layer 2 and the heating resistor 3.

Next, the operation of the thermal print head A having the above configuration will be described.

In the thermal print head A of the present embodiment, a plurality of recesses are formed on the extended portions 41B of the common electrode 41 and the surfaces 41Ba and 42a of the individual electrodes 42. For this reason, part of the protective film 6 (formed on the upper layer side of the electrode layer 4) enters the concave portions of the surfaces 41Ba and 42a, and the adhesion of the protective film 6 can be improved by the so-called anchor effect. Therefore, it is possible to suppress the peeling of the protective film 6 and improve the durability of the thermal print head A1. In this embodiment, the center line average roughness Ra of the surfaces 41Ba and 42a is 0.1. When it is set to ˜0.5 / zm, the above-described anchor effect is appropriately exhibited, which is suitable for suppressing peeling of the protective film 6.

[0030] In addition, a relatively large stress is generated in the protective film 6 in the direction along the boundary surface due to the difference in thermal expansion coefficient between Au constituting the electrode layer 4 and glass constituting the protective film 6. sell. However, according to the present embodiment, the displacement in the direction along the boundary surface is less likely to occur, which is suitable for suppressing the peeling of the protective film.

[0031] Since the metal thin film 5 containing Ni, Cr, or Ti is formed on the upper side of the common line 41A of the common electrode 41, the adhesion of the protective film 6 can be increased. . Specifically, metals such as Ni, Cr, and Ti have a large ionization tendency and are unstable compared to Au, and therefore, an oxide film is easily formed on the surface. The presence of the oxide film makes it possible to ensure adhesion with glass. Therefore, by interposing the metal thin film 5 between the electrode layer 4 (common line portion 41A in this embodiment) and the protective film 6, the peeling of the protective film 6 is suppressed and the durability of the thermal print head is improved. be able to. In addition, since the above metal has excellent adhesion to Au, when the metal thin film 5 is peeled off from the electrode layer 4, no defects are caused.

[0032] The common line portion 41A and the metal thin film 5 are formed with a plurality of through holes h that communicate with the lower surface of the common line portion 41A. Here, the protective film 6 formed on the upper layer side of the common line portion 41A directly enters the through hole h and directly contacts the glaze layer 2 and the heating resistor 3 formed on the lower layer side of the common line portion 41A. In close contact. Since the glaze layer 2 or the heating resistor 3 has better adhesion to the protective film 6 than the electrode layer 4, it is protected by securing an adhesion area between the protective film 6 and the glaze layer 2 or the heating resistor 3. The adhesion with the film 6 is improved, and as a result, peeling of the protective film 6 can be suppressed. Further, since a part of the protective film 6 enters the through hole h, even if stress is generated in the protective film 6 along the boundary surface with the lower layer, the displacement in the direction along the boundary surface hardly occurs. Become. Therefore, it is suitable for suppressing peeling of the protective film 6. Furthermore, when the diameter of the through hole h is 1 to 10 / ζ πι, a part of the protective film 6 is appropriately filled in the through hole h, while the sectional area of the common line portion 41A is reduced. It can avoid becoming extremely small. As a result, an increase in voltage drop in the common line portion 41A is suppressed, which is preferable. As described above, the slit is used as the penetration portion. Even when the S (Fig. IB) is formed, part of the protective film 6 that has entered the slit S directly adheres to the glaze layer 2 or the heating resistor 3, thereby suppressing the peeling of the protective film 6. can do. Here, it is preferable that the slit S be formed so as to extend in a direction substantially orthogonal to the width direction of the common line portion 41A. The width (short side length) of the slit S is preferably 1 to 10 / ζ πι. Is preferred. In this case, an increase in the amount of voltage drop in the common line portion 41A, where the cross-sectional area of the common line portion 41A does not become extremely small, is suppressed.

[0033] The common line portion 41A of the common electrode 41 is a portion for supplying a current to the heating resistor portions 31 at once, and is formed to have a relatively large area.

FIG. 4 is a cross-sectional view (corresponding to FIG. 3) for explaining a modified example of the thermal print head based on the present embodiment. In the thermal print head Ala shown in FIG. 4, an insulating film 8 is formed on the lower layer side of the common line portion 41A. For the insulating film 8, a material having excellent adhesion to the constituent material of the protective film 6 (for example, SiO, SiN, etc.) is appropriately selected and used, for example, Ta

2

Consists of O. Insulating film 8 has better adhesion to protective film 6 than electrode layer 4

twenty five

Therefore, in the thermal print head Ala, a part of the protective film 6 enters the through hole h and directly contacts the insulating film 8, thereby improving the adhesion of the protective film 6 and preventing the protective film 6 from being peeled off. Can be suppressed. In addition, the insulating film 8 has better adhesion to the protective film 6 than the glaze layer 2 and the heating resistor 3. As a result, the thermal print head Ala has an electrode layer 4 formed on the insulating film 8, and even though the thermal print head Ala is in a range, the adhesive force of the protective film 6 is higher than that of the thermal print head A 1 described above. improves. Therefore, according to the thermal print head Ala, peeling of the protective film 6 can be more effectively suppressed.

[0035] FIGS. 5 and 6 show a thermal print head A2 according to a second embodiment of the present invention.

In FIG. 5 and subsequent drawings, the same or similar elements as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment.

The thermal print head A2 includes a substrate 1, a glaze layer 2, a heating resistor 3, a common electrode 410, a plurality of individual electrodes 420, and a protective film 6. In FIG. 5, the protective film 6 is omitted.

[0037] On the substrate 1, a glaze layer 2, an electrode layer 4, a heating resistor 3 and a protective film 6 are sequentially laminated. The glaze layer 2 has a raised portion 21 whose outer surface is raised in a substantially arc shape. Yes. The electrode layer 4 is laminated on the upper layer side of the glaze layer 2. Part of the electrode layer 4 is selectively etched, and a common electrode 410 and individual electrodes 420 are formed by performing a heat treatment to be described later.

[0038] The common electrode 410 has the same shape as that of the first embodiment, and includes a common line portion 410A and a plurality of extending portions 410B. However, the through hole is not formed in the common line portion 410A, and this is different from the shape of the common electrode 41 in the first embodiment. Each individual electrode 420 is formed at a distance from each extending portion 410B so as to expose a part of the raised portion 21 in the vicinity of the top surface of the raised portion 21 of the glaze layer. In the common electrode 410 and the individual electrode 420, the glass component of the lower glaze layer 2 diffuses to the vicinity of these surfaces. In FIG. 6 and FIGS. 7 to 10, the glass component diffused near the surface of the electrode is schematically represented by dots. Such diffusion of the glass component is achieved by performing a heat treatment described later.

The heating resistor 3 is laminated on the upper layer side of the electrode layer 4. The heating resistor 3 is formed so as to cover the exposed portion of the raised portion 21 of the glaze layer and to straddle one end portion of the extending portion 410B and one end portion of the individual electrode 420. Of the heating resistor 3, an exposed portion between the extending portion 410B and the individual electrode 420 opposed thereto functions as the heating resistor 31 and is configured to form one heating dot. Therefore, in this embodiment, the heating resistor 3 is formed on the upper layer side of the electrode layer 4 and the metal thin film 5 is formed. On the other hand, the laminated structure of the first embodiment is used. Is different.

[0040] Next, an example of a method for manufacturing the above-described thermal print head A2 will be described with reference to FIGS.

First, as shown in FIG. 7A, the glaze layer 2 is formed on the substrate 1 so as to have a raised portion 21 whose outer surface is raised in a substantially arc shape. The glaze layer 2 is formed by printing and baking a glass paste. Next, as shown in FIG. 7B, an electrode layer 4 is formed on the glaze layer 2. The electrode layer 4 is formed by printing and baking a metal paste mainly composed of Au. Subsequently, a part of the electrode layer 4 is selectively etched by photolithography or the like to form a common electrode 410 ′ and individual electrodes 420 ′ in which the glass component is not diffused, as shown in FIG. 7C. Next, the substrate 1 is subjected to a heat treatment at 800 ° C. to 900 ° C. for 1 hour, for example. Au, which is the main component of the electrode, has the property of easily diffusing impurities. For this reason, as shown in FIG. 7D, the glass component of the glaze layer 2 diffuses into the common electrode 410 ′ and the individual electrode 420 ′, and the common electrode 410 and the individual electrode 42 0 containing the glass component in the vicinity of these surfaces. Is formed.

Next, as shown in FIG. 8A, a heating resistor layer 3 ′ is formed. The heating resistor layer 3 ′ is formed by, for example, depositing TaSiO by CVD or sputtering.

2

Do. Subsequently, unnecessary portions of the heating resistor layer 3 ′ are removed by etching to form the heating resistor 3 as shown in FIG. 8B.

Next, as shown in FIG. 9, a protective film 6 is formed. The protective film 6 is formed by, for example, SiO

2 Alternatively, SiN is deposited by CVD or sputtering.

According to the present embodiment, the glass component of the glaze layer 2 is diffused near the surfaces of the common electrode 410 and the individual electrode 420. Since glass has better adhesion to the protective film 6 than Au, the glass component diffused near the surface of the common electrode 410 and the individual electrode 420 functions as an adhesive, and the adhesion of the protective film 6 is improved. . Therefore, it is possible to improve the durability of the thermal print head A2.

FIG. 10 is a cross-sectional view for explaining a modification of the thermal print head according to the second embodiment. The thermal print head A2a shown in FIG. 10 has a configuration in which a metal film 9 is formed between the glaze layer 2 and the electrode layer 4 by a sputtering method or the like. The metal film 9 is formed by forming a metal containing, for example, Ni, Cr, or Ti on the glaze layer 2 by sputtering. In the thermal print head A2a, by performing heat treatment after the electrodes are formed as described above, the metal components contained in the metal film 9 are diffused to the vicinity of the surface, thereby forming the common electrode 411 and the individual electrodes 421. Since the metal has better adhesion to the protective film 6 than Au, the metal component diffused in the vicinity of the surfaces of the common electrode 411 and the individual electrode 421 functions as an adhesive, and the adhesion of the protective film 6 is improved. improves. Depending on the type of protective film 6, the metal component of the metal film 9 may have better adhesion to the protective film 6 than the glass component of the glaze layer 2, and if this is applied, the thermal print head A2a is preferred. The metal film 9 is a thin film having a predetermined thickness or less. Thus, also in the thermal print head A2a, the glass component of the glaze layer 2 can be expected to diffuse to the vicinity of the surfaces of the common electrode 411 and the individual electrode 421.

[0047] The present invention is not limited to the embodiments described above. For example, the recesses formed in the electrodes are not limited to those formed by etching, and may be formed by other methods such as sandblasting or using a stepper.

[0048] In the first embodiment, the formation of the recess by light etching may be performed on only a part of the electrode, or may be performed on the entire electrode. Similarly, the formation of the metal thin film 5 or the through hole h may be performed on only a part of the electrode or may be performed on the entire electrode.

In the present invention, the through portion is not limited to a through hole having a circular shape in plan view or a slit having a rectangular shape in plan view. The shape, number, arrangement, and the like of the through portions can be set as appropriate.

[0050] The protective film is not limited to the single-layer structure in each of the above embodiments. For example, the protective film may have a laminated structure including two or more layers provided with an abrasion resistant layer. The thermal print head of the present invention may be a thin film type or a thick film type.

Claims

The scope of the claims

[I] a substrate, a glaze layer, a heating resistor, an electrode mainly composed of Au for energizing the heating resistor, and a protective film covering the heating resistor and the electrode. A thermal print head in which a plurality of recesses are formed on the surface of the electrode.

[2] The thermal print head according to claim 1, wherein the plurality of recesses are formed such that the center line average roughness Ra of the surface of the electrode is 0.1 to 0.5 μm.

[3] The thermal print head according to claim 1, wherein the plurality of concave portions are formed by a plurality of through portions penetrating in the thickness direction of the electrode.

[4] The thermal print head according to claim 3, wherein each penetrating portion has a circular cross section.

[5] The thermal print head according to claim 4, wherein each through hole has a diameter of 1 to 10 μm.

6. The thermal print head according to claim 3, wherein each penetrating portion has a rectangular cross section.

[7] The rectangle has a short side and a long side, and the length of the short side is 1 to: LO / z m

The thermal print head according to claim 6.

8. The thermal print head according to claim 3, further comprising an insulating film formed on a lower layer side of the electrode.

[9] It includes a substrate, a glaze layer, a heating resistor, an electrode containing Au as a main component for energizing the heating resistor, and a protective film covering the heating resistor and the electrode. A thermal print head in which a metal thin film containing at least one of Ni, Cr, and Ti is formed on the electrode.

[10] A step of forming a glaze layer on the substrate, a step of forming an electrode mainly composed of Au on the glaze layer, a step of forming a heating resistor, and covering the heating resistor and the electrode In the configuration having a step of forming a protective film,

A method of manufacturing a thermal print head, comprising a step of heat-treating the substrate after the step of forming the electrode.

[II] The thermal print head according to claim 10, further comprising a step of forming a metal film containing at least one of Ni, Cr, and Ti between the glaze layer and the electrode. Production method.