Thermal print head and method of manufacturing thermal print head

Abstract

To provide a thermal print head on which a protective film is easily formed.SOLUTION: A thermal print head 100 includes: a substrate 1; a first protective film 41; and a second protective film 42. The substrate 1 has a first surface 10a and a first side surface 10c. The first surface 10a is provided with a heating section 2. The first side surface 10c is continuous to the first surface 10a. The first protective film 41 covers the heating section 2. The second protective film 42 is provided on the first protective film 41. A side surface 42d of the second protective film 42 is on the same plane as the first side surface 10c.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to thermal printheads and methods for manufacturing thermal printheads. [Background technology]

[0002] Japanese Patent Application Laid-Open No. 2022-78589 (Patent Document 1) discloses a thermal printhead having a protective layer that covers a heat generating portion. The protective layer is made of glass. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-78589 A [Summary] Conventionally, to improve the durability of thermal printheads, multiple substrates are stacked so that portions of the substrates overlap each other, and a protective film is formed on the surface of the substrate using sputtering. However, as the short sides of the substrates become shorter, the overlapping area of ​​the substrates shrinks. Therefore, there is room for improvement in forming a durable protective film.

[0004] A thermal printhead according to one embodiment of the present disclosure includes a substrate, a first protective film, and a second protective film. The substrate has a first surface and a first side surface. A heat generating portion is provided on the first surface. The first side surface is continuous with the first surface. The first protective film covers the heat generating portion. The second protective film is provided on the first protective film. The side surface of the second protective film is flush with the first side surface.

[0005] A method for manufacturing a thermal printhead according to one embodiment of the present disclosure is a method for manufacturing a thermal printhead including a substrate having a first surface on which a heat generating portion is provided, the method comprising the steps of forming a first protective film on a portion of the first surface so as to cover the heat generating portion, forming a mask layer on the first surface exposed from the first protective film, forming a second protective film on the mask layer and on the first protective film, and, after the step of forming the second protective film, removing the mask layer together with the second protective film formed on the mask layer. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a schematic plan view of a thermal printhead according to a first embodiment. [Figure 2] FIG. 2 is a schematic partial cross-sectional view of the thermal printhead taken along line II-II in FIG. [Figure 3] FIG. 3 is a flowchart showing a method for manufacturing the thermal printhead according to the first embodiment. [Figure 4] FIG. 4 is a schematic plan view showing one step in the method for manufacturing the thermal printhead according to the first embodiment. [Figure 5] FIG. 5 is a schematic plan view showing a step subsequent to the step shown in FIG. 4 in the method for manufacturing the thermal printhead according to the first embodiment. [Figure 6] FIG. 6 is a schematic plan view showing a step subsequent to the step shown in FIG. 5 in the method for manufacturing the thermal printhead according to the first embodiment. [Figure 7] FIG. 7 is a schematic partial cross-sectional view of the thermal printhead taken along line VII-VII in FIG. [Figure 8] FIG. 8 is a schematic plan view showing a step subsequent to the step shown in FIG. 6 in the method for manufacturing the thermal printhead according to the first embodiment. [Figure 9] FIG. 9 is a schematic partial cross-sectional view of the thermal printhead taken along line IX-IX in FIG. [Figure 10]FIG. 10 is a schematic plan view showing a step subsequent to the step shown in FIG. 8 in the method for manufacturing the thermal printhead according to the first embodiment. [Figure 11] FIG. 11 is a schematic partial cross-sectional view of the thermal printhead taken along line XI-XI in FIG. [Figure 12] 12 is a schematic plan view showing a step subsequent to the step shown in FIG. 10 in the method for manufacturing the thermal printhead of the first embodiment. [Detailed Description] The details of the embodiments of the present disclosure will be described with reference to the drawings. Note that the same or corresponding parts in the following drawings are designated by the same reference numerals, and their description will not be repeated. At least some of the configurations of the embodiments described below may be combined in any manner.

[0007] Embodiment 1 (Thermal printhead configuration) Fig. 1 is a schematic plan view of a thermal printhead 100 according to the first embodiment. Fig. 2 is a schematic partial cross-sectional view of the thermal printhead 100 taken along line II-II in Fig. 1.

[0008] The thermal printhead 100 shown in FIGS. 1 and 2 comprises a substrate 1, a heat generating portion 2, a wiring layer 3, and a protective film 4.

[0009] As shown in FIG. 2, the substrate 1 has a first surface 10a and a second surface 10b. The first surface 10a and the second surface 10b are end surfaces of the substrate 1 in the thickness direction. The second surface 10b is the surface located opposite the first surface 10a. The shape of the substrate 1 in a plan view of the first surface 10a is, for example, rectangular. The direction perpendicular to the first surface 10a is the z direction. The direction perpendicular to the z direction is the x direction. The direction perpendicular to the x direction and the z direction is the y direction. The plan view refers to the case where the substrate 1 is viewed from the first surface 10a side along the z direction of the first surface 10a. The x direction corresponds to the longitudinal direction of the substrate 1 in a plan view. As will be described later, the x direction is the direction in which the heat generating portion 2 extends. The y direction corresponds to the lateral direction of the substrate 1 in a plan view.

[0010] The substrate 1 has a first side surface 10c and a second side surface 10d. The first side surface 10c is continuous with the first surface 10a and the second surface 10b. The second side surface 10d is continuous with the first surface 10a and the second surface 10b. Each of the first side surface 10c and the second side surface 10d is a surface that connects the first surface 10a and the second surface 10b. The second side surface 10d is located opposite the first side surface 10c in the y direction.

[0011] The material constituting the substrate 1 is, for example, ceramic, and may be, for example, a material containing ceramic such as alumina (Al2O3) as a main component.

[0012] 2, the heat generating portion 2 includes a partial glaze layer 20 and a resistor 21. The heat generating portion 2 extends in the x direction. In a plan view of the first surface 10a, the heat generating portion 2 is disposed on the first side surface 10c side. In other words, the distance from the first side surface 10c to the heat generating portion 2 in the y direction is shorter than the distance from the second side surface 10d to the heat generating portion 2 in the y direction.

[0013] The partial glaze layer 20 is formed on the first surface 10a. Specifically, the partial glaze layer 20 is not formed over the entire first surface 10a, but is formed on a partial region of the first surface 10a. From a different perspective, the partial glaze layer 20 protrudes from a portion of the first surface 10a of the substrate 1. The partial glaze layer 20 is provided to increase the height of the resistor 21 from the first surface 10a of the substrate 1 and press the resistor 21 against a printing medium (e.g., thermal recording paper). The thickness of the partial glaze layer 20 in the z direction may be, for example, 10 μm or more and 50 μm or less.

[0014] The partial glaze layer 20 extends in the x direction. As shown in Fig. 2, the cross-sectional shape of the partial glaze layer 20 in a cross section perpendicular to the direction in which the partial glaze layer 20 extends may be, for example, an arc shape. The material constituting the partial glaze layer 20 is, for example, glass.

[0015] The partial glaze layer 20 is, for example, a heater glaze that stores heat from the heat generating portion 2. The partial glaze layer 20 is disposed below the resistor 21. The partial glaze layer 20 prevents the heat from the resistor 21 from dissipating to the substrate 1.

[0016] As shown in FIG. 2, the wiring layer 3 is formed on the first surface 10a and the partial glaze layer 20. As shown in FIG. 1, the wiring layer 3 has a main body portion 30a, multiple protrusions 30b, and multiple individual electrode portions 31. In a plan view of the first surface 10a, the main body portion 30a has, for example, a rectangular shape. The main body portion 30a extends along the x direction. The main body portion 30a is located on the first side surface 10c side in the y direction. That is, the distance between the main body portion 30a and the first side surface 10c in the y direction is smaller than the distance between the main body portion 30a and the second side surface 10d in the y direction. The protrusions 30b protrude along the y direction from the side of the main body portion 30a facing the second side surface 10d. The protrusions 30b are arranged on the partial glaze layer 20 so as to overlap the resistor 21. The multiple protrusions 30b are arranged at equal intervals along the x direction.

[0017] One end of the individual electrode portion 31 in the y direction is closer to the first side surface 10c than the other end of the individual electrode portion 31 in the y direction. The individual electrode portion 31 has a tip portion 31a at one end in the y direction. The tip portion 31a extends along the y direction. As shown in FIG. 2, the tip portion 31a is disposed on the partial glaze layer 20 so as to overlap the resistor 21. The protrusions 30b and the tip portions 31a are alternately disposed at intervals in the x direction. The individual electrode portion 31 has a pad 31b at the other end in the y direction. The thermal printhead 100 is electrically connected to a driver IC (not shown) at the pad 31b.

[0018] The material forming the wiring layer 3 is, for example, a conductive material. Specifically, the material forming the wiring layer 3 is a metal material. The material forming the wiring layer 3 may be, for example, gold (Au).

[0019] The resistor 21 is formed so as to be connected to the individual electrode portion 31. The resistor 21 extends along the x direction. A portion of the resistor 21 overlaps the protrusion 30b and the tip portion 31a.

[0020] The resistor 21 includes, for example, glass and a plurality of conductive particles mixed in the glass. The conductive particles are made of, for example, ruthenium oxide (RuO2).

[0021] The driver IC selectively applies a voltage to the individual electrode portion 31. This causes a current to flow through the portion of the resistor 21 that electrically connects the tip 31a of the individual electrode portion 31 to which the voltage is applied and the adjacent protrusion 30b. As a result, the resistor 21 generates heat. This heat causes printing on paper that is in contact with the heating portion 2.

[0022] As shown in FIG. 1, the protective film 4 is formed so as to cover the heat generating portion 2. In FIG. 1, the part of the wiring layer 3 and the heat generating portion 2 that are covered by the protective film 4 are indicated by dotted lines. The protective film 4 is not formed over the entire first surface 10a, and the pads 31b are exposed from the protective film 4. From a different perspective, in a plan view of the first surface 10a, the protective film 4 overlaps the heat generating portion 2. In a plan view of the first surface 10a, the protective film 4 does not overlap the pads 31b.

[0023] 2, the protective film 4 includes a first protective film 41 and a second protective film 42. The first protective film 41 covers the heat generating portion 2 and is directly connected to the substrate 1, the heat generating portion 2, and the wiring layer 3. The material constituting the first protective film 41 is, for example, glass. The first protective film 41 may be formed, for example, by applying a glass paste so as to cover the heat generating portion 2 and then firing the glass paste.

[0024] The second protective film 42 is provided on the first protective film 41. The second protective film 42 may be formed by sputtering. The material constituting the second protective film 42 is, for example, any one of silicon carbide (SiC), titanium (Ti), ceramic, and sialon (SiAlON).

[0025] The Vickers hardness of the second protective film 42 may be, for example, 1000 HV or more. This results in a thermal printhead 100 with improved durability. The Vickers hardness is measured using a Mitutoyo micro Vickers hardness tester (HM-100) in accordance with the Vickers hardness testing method specified in the JIS standard (JIS Z 2244-1:2020).

[0026] The thickness h of the second protective film 42 in the z direction is, for example, 4 μm or more. The thickness h of the second protective film 42 in the z direction may be 7 μm or less.

[0027] A feature of the thermal printhead 100 according to the first embodiment is that the side surface of the protective film 4 is flush with the first side surface 10c of the substrate 1, as shown in Fig. 2. As will be described later, in the step (S6) of singulating the substrate 1, the substrate 1 is cut along the cutting line L1 shown in Fig. 12 when singulating the substrate 1. As a result, the side surface 41c of the first protective film 41 and the side surface 42c of the second protective film 42 are flush with the first side surface 10c of the substrate 1. In this way, a protective film 4 with improved durability can be easily obtained.

[0028] Note that "on the same plane" does not only mean that the side surface 41c of the first protective film 41 and the side surface 42c of the second protective film 42 are on the exact same plane as the first side surface 10c of the substrate 1, but also means that the side surfaces 41c and 42c are within a range of 1 μm or less above and below the first side surface 10c, and also means that the side surfaces are on approximately the same plane.

[0029] 2, the first protective film 41 has a side surface 41c and a side surface 41d. The side surface 41c is located opposite the side surface 41d in the y direction. The side surfaces 41c and 41d extend, for example, along the x direction and the z direction. That is, the side surfaces 41c and 41d are surfaces that are substantially perpendicular to the y direction.

[0030] 2, the second protective film 42 has a surface 42a and a side surface 42c and a side surface 42d. The surface 42a is located opposite the surface where the second protective film 42 is connected to the first protective film 41. The side surface 42c is located opposite the side surface 42d in the y direction. The side surfaces 42c and 42d are each continuous with the surface 42a. The side surfaces 42c and 42d extend, for example, along the x and z directions. That is, the side surfaces 42c and 42d are surfaces that are substantially perpendicular to the y direction.

[0031] As shown in FIG. 2, when viewed from the heat generating portion 2, the side surface 41c of the first protective film 41 and the side surface 42c of the second protective film 42 are located in the region in the y direction where the first side surface 10c of the substrate 1 is located.

[0032] The side surface 42c is continuous with the side surface 41c. The side surface 41c is continuous with the first side surface 10c. The first side surface 10c is a surface that is substantially perpendicular to the y direction. The first side surface 10c of the substrate 1 extends along the x direction and the z direction. In other words, the side surface 41c of the first protective film 41 and the side surface 42c of the second protective film 42 are substantially on the same plane as the first side surface 10c of the substrate 1.

[0033] When viewed from the heat generating portion 2, the side surface 41d of the first protective film 41 and the side surface 42d of the second protective film 42 are located in the region in the y direction where the second side surface 10d of the substrate 1 is located. The side surface 42d is continuous with the side surface 41d. The side surface 41d is continuous with the first surface 10a so as to be substantially perpendicular to the first surface 10a. The side surface 41d of the first protective film 41 and the side surface 42d of the second protective film 42 are each located between the heat generating portion 2 and the second side surface 10d in the y direction.

[0034] Minute irregularities may be formed on the side surface 42d of the second protective film 42. In other words, the surface roughness of the side surface 42d of the second protective film 42 may be greater than the surface roughness of the surface 42a.

[0035] (Thermal printhead manufacturing method) The following describes a method for manufacturing the thermal printhead 100. Figure 3 is a flowchart of the method for manufacturing the thermal printhead 100 of the first embodiment.

[0036] As shown in FIG. 4, the method for manufacturing the thermal printhead 100 first performs the step (S1) of preparing a substrate 1. In this step (S1), the substrate 1 is prepared as shown in FIG. 4. The substrate 1 is, for example, an insulating substrate made of ceramic. The width of the prepared substrate 1 in the y direction is, for example, 2 mm or less. The substrate 1 has a first surface 10a. A plurality of heat generating portions 2 and a plurality of wiring layers 3 are formed on the prepared first surface 10a. As shown in FIG. 4, the plurality of heat generating portions 2 extend in the x direction. Note that the wiring layer 3 is not shown in FIG. 4.

[0037] Next, a step (S2) of forming first protective films 41 is performed. In this step (S7), as shown in FIG. 5, a plurality of first protective films 41 are formed on parts of first surface 10a so as to cover heat generating portion 2. That is, first protective films 41 are formed along the direction in which heat generating portion 2 extends (x direction). In a plan view of first surface 10a, first protective films 41 are formed so as to overlap heat generating portion 2 but not pad 31b. Therefore, as shown in FIG. 5, parts of first surface 10a are exposed in areas where first protective films 41 are not formed.

[0038] Next, a step (S3) of forming a mask layer 5 is performed. In this step (S3), as shown in FIGS. 6 and 7, a plurality of mask layers 5 are formed on the first surface 10a exposed from the first protective film 41 and on the wiring layer 3. The mask layers 5 are formed, for example, by screen printing or using a dispenser. As shown in FIG. 7, the height of the mask layers 5 in the z direction may be greater than the height of the heat generating portion 2 in the z direction. The mask layers 5 are arranged so as to be sandwiched between adjacent first protective films 41. The mask layers 5 may be arranged so as to be in contact with the side surfaces 41c and 41d of the first protective films 41.

[0039] As will be described later, in the step (S4) of forming the second protective film 42, the second protective film 42 is formed by sputtering. The second protective film 42 is formed by sputtering in an atmosphere at about 200°C. That is, in the step (S4) of forming the second protective film 42, the mask layer 5 does not melt, so the mask layer 5 may be heat-resistant, for example. The material constituting the mask layer 5 may be, for example, polyimide or polyamide.

[0040] As will be described later, in the step (S5) of removing the mask layer 5, pressure is applied to the mask layer 5, whereby the mask layer 5 is destroyed and removed. Therefore, the mask layer 5 may be softer than the second protective film 42. From a different perspective, the Vickers hardness of the mask layer 5 may be lower than the Vickers hardness of the second protective film 42.

[0041] Next, a step (S4) of forming second protective film 42 is performed. In this step (S4), second protective film 42 is formed on mask layer 5 and on first protective film 41, as shown in FIGS. 8 and 9.

[0042] The second protective film 42 is formed by, for example, sputtering. The thickness h of the second protective film 42 in the z direction is, for example, not less than 4 μm and not more than 7 μm. The material that forms the second protective film 42 is, for example, any one of silicon carbide, titanium, ceramic, and sialon.

[0043] The Vickers hardness of the second protective film 42 may be, for example, 1000 HV or more, thereby providing a thermal printhead 100 with improved durability.

[0044] Next, a step (S5) of removing mask layer 5 is performed. The step (S5) of removing mask layer 5 is performed after the step (S4) of forming second protective film 42. In this step (S5), mask layer 5 is removed together with second protective film 42 formed on mask layer 5, as shown in FIGS. 10 and 11 .

[0045] As described above, the mask layer 5 is softer than the second protective film 42. Therefore, by applying pressure to the second protective film 42 formed on the mask layer 5, pressure is indirectly applied to the mask layer 5. As a result, the mask layer 5 is destroyed, and the second protective film 42 formed on the mask layer 5 can be removed together with the mask layer 5. Meanwhile, as shown in FIG. 11 , the second protective film 42 formed on the first protective film 41 (the second protective film 42 not formed on the mask layer 5) remains without being removed. As a result, a portion of the first surface 10a is exposed from the protective film 4.

[0046] The mask layer 5 may be removed using, for example, a roller. By using the roller to apply pressure from above the second protective film 42 formed on the mask layer 5, the mask layer 5 and the second protective film 42 formed on the mask layer 5 are removed together.

[0047] The mask layer 5 may be removed by, for example, wet blasting. By using wet blasting, a liquid containing an abrasive is sprayed toward the second protective film 42, and the second protective film 42 formed on the mask layer 5 is removed together with the mask layer 5.

[0048] 10 and 11, removing the mask layer 5 forms a side surface 42c and a side surface 42d of the second protective film 42. The side surface 42d of the second protective film 42 forms a fractured surface. The fractured surface is continuous with the side surface 41d of the first protective film 41. The side surface 42d of the second protective film 42 may have minute irregularities. In other words, the surface roughness of the side surface 42d of the second protective film 42 may be greater than the surface roughness of the surface 42a.

[0049] In particular, when the mask layer 5 is removed using wet blasting, the portion where the side surface 42d joins the surface 42a may be curved.

[0050] Next, a step (S6) of dividing the substrate 1 into individual pieces is performed. The step (S6) of dividing the substrate 1 into individual pieces is performed after the step (S5) of removing the mask layer 5. In this step (S6), the substrate 1 is cut along cutting lines L shown in FIG.

[0051] The cutting line L is along the side surface 41c of the first protective film 41. By cutting the substrate 1 along the cutting line L, the first side surface 10c and the second side surface 10d of the substrate 1 are formed. As a result, the side surface 41c of the first protective film 41 and the side surface 42c of the second protective film 42 are flush with the first side surface 10c of the substrate 1. In this manner, the individualized thermal printheads 100 shown in FIGS. 1 and 2 are obtained.

[0052] (Action and effect) A thermal printhead 100 according to the present disclosure includes a substrate 1, a first protective film 41, and a second protective film 42. The substrate 1 has a first surface 10a and a first side surface 10c. A heat generating portion 2 is provided on the first surface 10a. The first side surface 10c is continuous with the first surface 10a. The first protective film 41 covers the heat generating portion 2. The second protective film 42 is provided on the first protective film 41. A side surface 42d of the second protective film 42 is flush with the first side surface 10c.

[0053] This makes it easy to form a protective film 4 with improved durability even if the short side of the substrate 1 is short, resulting in a thermal printhead 100 with improved durability.

[0054] According to the thermal printhead 100, the material that forms the second protective film 42 is any one of silicon carbide, titanium, ceramic, and sialon.

[0055] In this way, a thermal printhead 100 with improved durability can be obtained. According to the thermal printhead 100, the material that forms the first protective film 41 is glass.

[0056] In this way, a thermal printhead 100 with improved durability can be obtained. In the thermal printhead 100, the thickness h of the second protective film 42 is 4 μm or more.

[0057] This makes it easy to form a protective film 4 with improved durability even if the short side of the substrate 1 is short, resulting in a thermal printhead 100 with improved durability.

[0058] According to the thermal printhead 100, the second protective film has a Vickers hardness of 1000 HV or more.

[0059] In this way, a thermal printhead 100 with improved durability can be obtained. A method for manufacturing a thermal printhead 100 according to the present disclosure is a method for manufacturing a thermal printhead 100 that includes a substrate 1 having a first surface 10a on which a heat generating portion 2 is provided. The method for manufacturing the thermal printhead 100 includes the steps of: forming a first protective film 41 on a portion of the first surface 10a so as to cover the heat generating portion 2; forming a mask layer 5 on the first surface 10a that is exposed from the first protective film 41; forming a second protective film 42 on the mask layer 5 and on the first protective film 41; and removing the mask layer 5 together with the second protective film 42 formed on the mask layer 5 after the step of forming the second protective film 42 (S4).

[0060] This makes it easy to form a protective film 4 with improved durability even if the short side of the substrate 1 is short, resulting in a thermal printhead 100 with improved durability.

[0061] According to the method for manufacturing the thermal printhead 100, in the step (S5) of removing the mask layer 5, the mask layer 5 is removed using a roller.

[0062] This makes it easy to form a protective film 4 with improved durability even if the short side of the substrate 1 is short, resulting in a thermal printhead 100 with improved durability.

[0063] According to the method for manufacturing the thermal printhead 100, in the step (S5) of removing the mask layer 5, the mask layer 5 is removed by wet blasting.

[0064] This makes it easy to form a protective film 4 with improved durability even if the short side of the substrate 1 is short, resulting in a thermal printhead 100 with improved durability.

[0065] The method for manufacturing the thermal printhead 100 includes a step (S6) of dividing the substrate 1 into individual pieces after the step (S5) of removing the mask layer 5.

[0066] In this way, the side surface 42d of the second protective film 42 is flush with the first side surface 10c. In other words, even if the short side of the substrate 1 is shortened, it is easy to form a protective film 4 with improved durability. As a result, a thermal printhead 100 with improved durability is obtained.

[0067] According to the method for manufacturing the thermal printhead 100, the Vickers hardness of the mask layer 5 is smaller than the Vickers hardness of the second protective film .

[0068] This makes it easy to form a protective film 4 with improved durability even if the short side of the substrate 1 is short, resulting in a thermal printhead 100 with improved durability.

[0069] According to the method for manufacturing the thermal printhead 100, the material constituting the second protective film 42 is any one of silicon carbide, titanium, ceramic, and sialon.

[0070] In this way, a thermal printhead 100 with improved durability can be obtained. According to the method for manufacturing the thermal printhead 100, the material that forms the first protective film 41 is glass.

[0071] In this way, a thermal printhead 100 with improved durability can be obtained. According to the method for manufacturing the thermal printhead 100, the thickness h of the second protective film 42 is 4 μm or more.

[0072] This makes it easy to form a protective film 4 with improved durability even if the short side of the substrate 1 is short, resulting in a thermal printhead 100 with improved durability.

[0073] According to the method for manufacturing the thermal printhead 100, the second protective film has a Vickers hardness of 1000 HV or more.

[0074] In this way, a thermal printhead 100 with improved durability can be obtained. The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. Unless there is a contradiction, at least two of the embodiments disclosed herein may be combined. The basic scope of the present disclosure is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0075] The present disclosure includes the following aspects. (Appendix 1) a substrate having a first surface on which a heat generating portion is provided and a first side surface connected to the first surface; a first protective film covering the heat generating portion; a second protective film provided on the first protective film, A thermal printhead, wherein the side surface of the second protective film is flush with the first side surface. (Appendix 2) 2. The thermal printhead according to claim 1, wherein the material constituting the second protective film is any one of silicon carbide, titanium, ceramic, and sialon. (Appendix 3) 3. The thermal printhead according to claim 1, wherein the material constituting the first protective film is glass. (Appendix 4) 4. The thermal printhead according to claim 1, wherein the second protective film has a thickness of 4 μm or more. (Appendix 5) 5. The thermal printhead according to claim 1, wherein the second protective film has a Vickers hardness of 1000 HV or more. (Appendix 6) A method for manufacturing a thermal printhead having a substrate with a first surface on which a heat generating portion is provided, comprising: forming a first protective film on a portion of the first surface so as to cover the heat generating portion; forming a mask layer on the first surface exposed from the first protective film; forming a second protective film on the mask layer and on the first protective film; A method for manufacturing a thermal printhead, comprising the step of removing the mask layer together with the second protective film formed on the mask layer after the step of forming the second protective film. (Appendix 7) In the step of removing the mask layer, 7. The method for manufacturing a thermal printhead described in claim 6, wherein the mask layer is removed using a roller. (Appendix 8) In the step of removing the mask layer, 7. The method for manufacturing a thermal printhead described in claim 6, wherein the mask layer is removed using wet blasting. (Appendix 9) Appendix 6: A method for manufacturing a thermal printhead, comprising the step of dividing the substrate into individual pieces after the step of removing the mask layer. (Appendix 10) 10. The method for manufacturing a thermal printhead according to any one of claims 6 to 9, wherein the mask layer has a lower Vickers hardness than the second protective film. (Appendix 11) 11. The method for manufacturing a thermal printhead according to any one of claims 6 to 10, wherein the material constituting the second protective film is any one of silicon carbide, titanium, ceramic, and sialon. (Appendix 12) 12. The method for manufacturing a thermal printhead according to claim 6, wherein the material constituting the first protective film is glass. (Appendix 13) 13. The method for manufacturing a thermal printhead according to claim 6, wherein the second protective film has a thickness of 4 μm or more. (Appendix 14) 14. The method for manufacturing a thermal printhead according to any one of claims 6 to 13, wherein the second protective film has a Vickers hardness of 1000 HV or more. [Explanation of symbols]

[0076] 1 substrate, 2 heating portion, 3 wiring layer, 4 protective film, 5 mask layer, 10a first surface, 10b second surface, 10c first side surface, 10d second side surface, 20 partial glaze layer, 21 resistor, 30a main body portion, 30b protrusion portion, 31 individual electrode portion, 31a tip portion, 31b pad, 41 first protective film, 41c, 41d, 42c, 42d side surface, 42 second protective film, 42a surface, 100 thermal print head, L cutting line.

Claims

1. a substrate having a first surface on which a heat generating portion is provided and a first side surface connected to the first surface; a first protective film covering the heat generating portion; a second protective film provided on the first protective film, A thermal printhead, wherein a side surface of the second protective film is flush with the first side surface.

2. 2. The thermal printhead according to claim 1, wherein the material constituting the second protective film is one of silicon carbide, titanium, ceramic, and sialon.

3. 2. The thermal printhead according to claim 1, wherein the material constituting the first protective film is glass.

4. The thermal printhead according to claim 1 , wherein the second protective film has a thickness of 4 μm or more.

5. 5. The thermal printhead according to claim 1, wherein the second protective film has a Vickers hardness of 1000 HV or more.

6. 1. A method for manufacturing a thermal printhead including a substrate having a first surface on which a heat generating portion is provided, the method comprising: forming a first protective film on a portion of the first surface so as to cover the heat generating portion; forming a mask layer on the first surface exposed from the first protective film; forming a second protective film on the mask layer and on the first protective film; a step of removing the mask layer together with the second protective film formed on the mask layer after the step of forming the second protective film.

7. In the step of removing the mask layer, The method for manufacturing a thermal printhead according to claim 6 , wherein the mask layer is removed using a roller.

8. In the step of removing the mask layer, The method of claim 6, wherein the mask layer is removed using wet blasting.

9. The method for manufacturing a thermal printhead according to claim 6 , further comprising the step of dividing the substrate into individual pieces after the step of removing the mask layer.

10. The method for manufacturing a thermal printhead according to claim 6 , wherein the Vickers hardness of the mask layer is lower than the Vickers hardness of the second protective film.

11. 7. The method for manufacturing a thermal printhead according to claim 6, wherein the material constituting the second protective film is one of silicon carbide, titanium, ceramic, and sialon.

12. The method for manufacturing a thermal printhead according to claim 6 , wherein the material constituting the first protective film is glass.

13. The method for manufacturing a thermal printhead according to claim 6 , wherein the second protective film has a thickness of 4 μm or more.

14. The method for manufacturing a thermal printhead according to claim 6 , wherein the second protective film has a Vickers hardness of 1000 HV or more.

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