Thermal print head

Abstract

To provide a thermal print head in which an increase in width of a heat generator is suppressed.SOLUTION: A thermal print head 100a includes an insulation board 1, a protrusion 7, and a heat generator 5. The insulation board 1 has a first surface 10a. The protrusion 7 is formed on the first surface 10a. The heat generator 5 has an edge portion 6. The edge portion 6 is connected to the protrusion 7. At least a part of the protrusion 7 includes a ceramic layer 4.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to thermal printheads. [Background technology]

[0002] Japanese Patent Application Laid-Open No. 2022-78589 (Patent Document 1) discloses a thermal printhead having a heating element. The heating element is formed on an insulating substrate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Document 1: JP 2022-78589 A [Summary] However, if an attempt is made to form the heating element taller in order to improve the printing efficiency of the thermal printhead, there is a risk that the width of the heating element will increase.

[0004] A thermal printhead according to one embodiment of the present disclosure includes an insulating substrate, a protrusion, and a heating element. The insulating substrate has a first surface. The protrusion is formed on the first surface. The heating element has an edge. The edge is connected to the protrusion. At least a portion of the protrusion includes a ceramic layer. [Brief description of the drawings]

[0005] [Figure 1] FIG. 1 is a schematic plan view of a thermal printhead according to a first embodiment. [Diagram 2] FIG. 2 is a schematic partial cross-sectional view of the thermal printhead taken along line II-II in FIG. [Diagram 3] FIG. 3 shows an insulating substrate having a ceramic layer formed on a first surface thereof. [Figure 4] FIG. 4 is a flowchart showing a method for manufacturing the thermal printhead according to the first embodiment. [Diagram 5] FIG. 5 is a schematic partial cross-sectional view showing a step in a method of manufacturing the thermal printhead according to the first embodiment. [Figure 6] FIG. 6 is a schematic partial cross-sectional 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 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 8] FIG. 8 is a schematic partial cross-sectional view showing a step subsequent to the step shown in FIG. 7 in the method for manufacturing the thermal printhead according to the first embodiment. [Figure 9] FIG. 9 is a schematic partial cross-sectional 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 10] FIG. 10 is a schematic partial cross-sectional view of a thermal printhead according to the second embodiment. [Figure 11] FIG. 11 is a flowchart of a method for manufacturing a thermal printhead according to the second embodiment. [Figure 12] FIG. 12 is a schematic partial cross-sectional view showing a step in a method of manufacturing the thermal printhead according to the second embodiment. [Figure 13] FIG. 13 is a schematic partial cross-sectional view showing a step subsequent to the step shown in FIG. 12 in the method of manufacturing the thermal printhead according to the second embodiment. [Figure 14] FIG. 14 is a schematic partial cross-sectional view showing a step subsequent to the step shown in FIG. 13 in the method of manufacturing the thermal printhead according to the second embodiment. [Figure 15] FIG. 15 is a schematic partial cross-sectional view showing a step subsequent to the step shown in FIG. 14 in the method of manufacturing the thermal printhead according to the second embodiment. [Figure 16] FIG. 16 is a schematic partial cross-sectional view of a thermal printhead according to the third embodiment. [Figure 17] FIG. 17 is a flowchart showing a method for manufacturing a thermal printhead according to the third embodiment. [Figure 18] FIG. 18 is a schematic partial cross-sectional view showing a step in a method of manufacturing the thermal printhead according to the third embodiment. [Figure 19] FIG. 19 is a schematic partial cross-sectional view showing a step subsequent to the step shown in FIG. 18 in the method of manufacturing the thermal printhead according to the third embodiment. [Figure 20] Fig. 20 is a schematic partial cross-sectional view showing a step subsequent to the step shown in Fig. 19 in the method for manufacturing a thermal printhead according to embodiment 3. [DETAILED DESCRIPTION] 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 given the same reference numerals, and their description will not be repeated. At least some configurations of the embodiments described below may be combined in any manner.

[0006] Embodiment 1 <Thermal print head configuration> Fig. 1 is a schematic plan view of a thermal printhead 100a according to embodiment 1. Fig. 2 is a schematic partial cross-sectional view of the thermal printhead 100a taken along line II-II in Fig. 1.

[0007] The thermal printhead 100a shown in FIGS. 1 and 2 comprises an insulating substrate 1, a glaze layer 20, a wiring layer 30, a ceramic layer 4, and a heating element 5. The thermal printhead 100a shown in FIGS.

[0008] As shown in FIG. 2, the insulating substrate 1 has a first surface 10a and a second surface 10b. The first surface 10a and the second surface 10b are end surfaces in the thickness direction of the insulating substrate 1. The second surface 10b is the surface opposite to the first surface 10a. The shape of the insulating substrate 1 in the 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 first surface 10a 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 insulating substrate 1 in the plan view. As will be described later, the x direction is the direction in which the heating element 5 and the protrusion 7 extend. The y direction corresponds to the lateral direction of the insulating substrate 1 in the plan view.

[0009] The insulating substrate 1 has a first side surface 10c and a second side surface 10d. Each of the first side surface 10c and the second side surface 10d connects the first surface 10a and the second surface 10b. The second side surface 10d is the surface on the opposite side to the first side surface 10c.

[0010] The material constituting the insulating substrate 1 is, for example, ceramic. The material constituting the insulating substrate 1 may be, for example, a material containing ceramic, such as alumina (Al2O3), as a main component.

[0011] 2, the ceramic layer 4 is formed on the first surface 10a. In the thermal printhead 100a according to the first embodiment, the ceramic layer 4 is directly connected to the first surface 10a. The ceramic layers 4 may be a pair, and the pair of ceramic layers 4 are disposed spaced apart from each other in the y direction.

[0012] The material constituting the ceramic layer 4 is a material containing ceramic as a main component. However, the composition of the ceramic layer 4 is different from the composition of the insulating substrate 1. For example, one of the features of the ceramic layer 4 is that the melting point of the ceramic layer 4 is equal to or lower than the melting point of the insulating substrate 1. The melting point of the insulating substrate 1 is, for example, 2000°C. The temperature at which the ceramic layer 4 is formed must be equal to or lower than the melting point of the insulating substrate 1. Therefore, the melting point of the ceramic layer 4 may be, for example, 1900°C or lower. The melting point of the ceramic layer 4 may be 1700°C or lower.

[0013] In addition, when forming the glaze layer 20, it is necessary to adjust the temperature so that the ceramic layer 4 and the glaze layer 20 are not integrated. Therefore, a feature of the ceramic layer 4 is that the melting point of the ceramic layer 4 is equal to or higher than the melting point of the glaze layer 20. As described above, the material constituting the glaze layer 20 is, for example, glass. The melting point of glass is, for example, 1000°C. Therefore, the melting point of the ceramic layer 4 may be 1100°C or higher. The ceramic layer 4 may be formed, for example, using a 3D printer. When the ceramic layer 4 is formed using a 3D printer, the ceramic layer 4 is formed (sintered) at, for example, 1200°C or higher. Therefore, the melting point of the ceramic layer 4 may be 1200°C or higher.

[0014] FIG. 3 shows an insulating substrate 1 having a ceramic layer 4 formed on a first surface 10a. As shown in FIG. 3, the surface properties of the ceramic layer 4 and the insulating substrate 1 are different from each other. Specifically, the surface roughness of the ceramic layer 4 is greater than the surface roughness of the first surface 10a. This is because the ceramic layer 4 contains particles having a particle size of 2.0 μm or less. The particle size of the particles contained in the ceramic layer 4 may be, for example, 0.15 μm or less. The particle size of the particles contained in the ceramic layer 4 may be, for example, 0.10 μm or less. The particle size of the particles contained in the ceramic layer 4 may be, for example, 0.05 μm or more. As shown in FIG. 3, the first surface 10a of the insulating substrate 1 is flat. On the other hand, the shape of the ceramic layer 4 is a convex shape protruding from the first surface 10a. In a cross section viewed from the x direction, the surface shape of the ceramic layer is curved.

[0015] As shown in FIG. 2, the glaze layer 20 is connected to the first surface 10a. As shown in FIG. 1, the glaze layer 20 may be formed on the entire surface of the first surface 10a. In a plan view of the first surface 10a, a part of the glaze layer 20 covers the ceramic layer 4. Specifically, the glaze layer 20 includes a coating glaze layer portion 2. The coating glaze layer portion 2 is connected to the ceramic layer 4. The coating glaze layer portion 2 may be a pair, and the pair of coating glaze layer portions 2 are arranged spaced apart from each other in the y direction. The material constituting the glaze layer 20 is, for example, glass.

[0016] 2, the wiring layer 30 is connected to the glaze layer 20. As shown in Fig. 1, the wiring layer 30 has a main body portion 30a, a plurality of protrusions 30b, and a plurality of individual electrode portions 31.

[0017] In a plan view of the first surface 10a, the shape of the main body 30a is, for example, rectangular. The main body 30a extends along the x direction. The main body 30a is on the first side surface 10c side in the y direction. That is, the distance between the main body 30a and the first side surface 10c in the y direction is smaller than the distance between the main body 30a and the second side surface 10d in the x direction. The protrusion 30b protrudes along the y direction from the side of the main body 30a facing the second side surface 10d. The multiple protrusions 30b are arranged at equal intervals along the x direction.

[0018] 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. The protrusions 30b and the tip portions 31a are alternately arranged 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 100a is electrically connected to a driver IC (not shown) at the pad 31b.

[0019] The material constituting the wiring layer 30 is, for example, a material having electrical conductivity. Specifically, the material constituting the wiring layer 30 is a metal material. The material constituting the wiring layer 30 may be, for example, gold (Au).

[0020] As shown in FIG. 2, a recess is formed in the tip portion 31a of the individual electrode portion 31. The heating element 5 is arranged so as to fill the recess. Specifically, the individual electrode portion 31 includes a first electrode portion 32a and a second electrode portion 32b. The first electrode portion 32a is connected to the pad 31b. The second electrode portion 32b is arranged to be spaced apart from the first electrode portion 32a in the y direction. As shown in FIG. 2, the second electrode portion 32b is arranged so as to be sandwiched between the first electrode portion 32a and the main body portion 30a in the y direction. The recess is formed by the first electrode portion 32a, the second electrode portion 32b, and the glaze layer 20 so that the glaze layer 20 forms the bottom surface of the recess.

[0021] In a plan view of the first surface 10a, a part of the wiring layer 30 covers the coated glaze layer portion 2. Specifically, the wiring layer 30 includes a first coated wiring portion 3a. The first coated wiring portion 3a may be a pair, and the pair of first coated wiring portions 3a are arranged spaced apart from each other in the y direction. Specifically, each of the first electrode portion 32a and the second electrode portion 32b may include the first coated wiring portion 3a.

[0022] In a plan view of the first surface 10a, the first coated wiring portion 3a covers the coated glaze layer portion 2. From a different perspective, in a plan view of the first surface 10a, the ceramic layer 4, the coated glaze layer portion 2, and the first coated wiring portion 3a are arranged to overlap each other. In this manner, a protrusion 7 is formed on the first surface 10a.

[0023] At least a portion of the protrusion 7 needs to include the ceramic layer 4. In the thermal printhead 100a according to the first embodiment, the protrusion 7 is formed by the ceramic layer 4, the coated glaze layer portion 2, and the first coated wiring portion 3a.

[0024] The protrusions 7 may be a pair. Specifically, the protrusions 7 may include a first protrusion 7a and a second protrusion 7b. The second protrusion 7b is disposed spaced apart from the first protrusion 7a in the y direction. The first covered wiring portion 3a included in the first electrode portion 32a may form a part of the first protrusion 7a. The first covered wiring portion 3a included in the second electrode portion 32b may form a part of the second protrusion 7b.

[0025] As shown in FIG. 2, the heating element 5 is formed so as to be connected to the individual electrode portion 31. The heating element 5 extends along the x direction. A portion of the heating element 5 overlaps the protruding portion 30b and the tip portion 31a. As described above, the heating element 5 fills the recess formed by being surrounded by the first electrode portion 32a and the second electrode portion 32b. The heating element 5 is disposed on the glaze layer 20.

[0026] A voltage is selectively applied to the individual electrode portion 31 by the driver IC. This causes a current to flow through a portion of the heating element 5 that electrically connects the tip portion 31a of the individual electrode portion 31 to which the voltage is applied and the adjacent protrusion portion 30b. As a result, the heating element 5 generates heat. This heat causes printing on paper in contact with the heating element 5.

[0027] The heating element 5 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).

[0028] The thermal printhead 100a further includes a protective glass (not shown). The protective glass covers the wiring layer 30 and the heating element 5. The pads 31b are exposed from the protective glass.

[0029] Here, the thermal printhead 100a according to the first embodiment is characterized in that the heating element 5 is disposed so as to be sandwiched between a first convex portion 7a and a second convex portion 7b, as shown in FIG. 2. Specifically, the heating element 5 has an edge portion 6. The edge portion 6 is connected to the convex portion 7. In a plan view seen from the z direction, the edge portion 6 has a first edge portion 6a and a second edge portion 6b. The first edge portion 6a is connected to the first convex portion 7a. The second edge portion 6b is connected to the second convex portion 7b. From a different perspective, as shown in FIG. 1, the first edge portion 6a and the second edge portion 6b are spaced apart in the y direction.

[0030] When forming the heating element 5, the heating element 5 is formed by firing a conductive paste. The conductive paste is a viscous fluid. Therefore, when attempting to form the heating element 5 high in a conventional thermal printhead that does not have a protrusion 7, the conductive paste spreads in the y direction. As a result, the width w of the heating element 5 formed by firing the conductive paste increases, and the amount of current required for printing increases. Furthermore, as the width w of the heating element 5 increases, the position where the heating element 5 is formed shifts, increasing the risk that the heating element 5 will interfere with the main body portion 30a.

[0031] On the other hand, in the thermal printhead 100a according to the first embodiment, when the heating element 5 is formed, the protrusions 7 suppress the width w of the heating element 5 from expanding. This is because the formation of the protrusions 7 causes surface tension to act on the conductive paste when the heating element 5 is formed. As a result, the height h of the heating element 5 can be increased while adjusting the width w of the heating element 5. In this way, the printing efficiency of the thermal printhead 100a is improved. Also, the risk of the heating element 5 interfering with the main body 30a due to a shift in the position at which the heating element 5 is formed is reduced.

[0032] The width of the heating element 5 in the y direction is defined as width w. The width w of the heating element 5 in the y direction is the distance from the first edge 6a to the second edge 6b in the y direction. The width w of the heating element 5 in the y direction may be, for example, 100 μm. The height of the heating element 5 in the z direction is defined as height h. In this embodiment 1, the height h of the heating element 5 in the z direction is the distance from the glaze layer 20 (the bottom surface of the recess formed by being surrounded by the first electrode portion 32a and the second electrode portion 32b) to the apex of the heating element 5.

[0033] By forming the protrusions 7, the heating element 5 can be formed so that the height h of the heating element 5 in the z direction is 0.03 times or more the width w of the heating element 5 in the y direction. The height h of the heating element 5 in the z direction may be 0.06 times or more the width w of the heating element 5 in the y direction. The height h of the heating element 5 in the z direction may be, for example, 3 μm or more. The height h of the heating element 5 in the z direction may be, for example, 6 μm or more.

[0034] As shown in FIG. 2, the first convex portion 7a includes a first vertex 71a. The first vertex 71a is the most distant point of the first convex portion 7a from the first surface 10a. The second convex portion 7b includes a second vertex 71b. The second vertex 71b is the most distant point of the second convex portion 7b from the first surface 10a. As shown in FIG. 2, each of the first edge portion 6a and the second edge portion 6b may be located between the first vertex 71a and the second vertex 71b in the y direction. From a different perspective, the width w of the heating element 5 in the y direction (the distance from the first edge portion 6a to the second edge portion 6b in the y direction) may be smaller than the distance from the first vertex 71a to the second vertex 71b in the y direction. In this way, when forming the heating element 5, the viscous conductive paste is prevented from spreading in the y direction beyond the vertex 71 of the convex portion 7. In other words, the protrusions 7 prevent the width w of the heating element 5 from increasing.

[0035] <Thermal printhead manufacturing method> A method for manufacturing the thermal printhead 100a will now be described. Fig. 4 is a flow chart showing the method for manufacturing the thermal printhead 100a of the first embodiment. Figs. 5 to 9 are schematic partial cross-sectional views showing a step in the method for manufacturing the thermal printhead 100a of the first embodiment.

[0036] As shown in Fig. 4, the method for manufacturing the thermal printhead 100a first performs a step (S1a) of preparing an insulating substrate 1. In this step (S1a), an insulating substrate 1 is prepared as shown in Fig. 5. In this step (S1a), no glaze layer 20 is disposed on the first surface 10a.

[0037] Next, a step (S2a) of forming the ceramic layer 4 is performed. In this step (S2a), as shown in FIG. 6, the ceramic layer 4 is formed on the first surface 10a. Specifically, the ceramic layer 4 may be formed using a 3D printer. The ceramic layer 4 may be formed by applying a solvent containing ceramic particles by a dispenser or screen printing. The viscosity of the solvent may be, for example, 60 Pa·S. The heat treatment temperature when forming the ceramic layer 4 may be equal to or lower than the melting point of the insulating substrate 1. The melting point of the insulating substrate 1 is, for example, 2000°C. Therefore, the heat treatment temperature when forming the ceramic layer 4 may be equal to or lower than 1900°C, for example, 1200°C.

[0038] Next, a step (S3a) of forming a glaze layer 20 is performed. In this step (S3a), as shown in FIG. 7, a glaze layer 20 is formed on the first surface 10a and the ceramic layer 4. Specifically, a paste containing glass is applied onto the first surface 10a and the ceramic layer 4. Next, the applied paste is heated at a temperature equal to or lower than the melting point of the ceramic layer 4. This causes the solvent in the paste to evaporate and the glass in the paste to bond to each other, thereby forming the glaze layer 20.

[0039] The glaze layer 20 thus formed includes an overlying glaze layer portion 2 covering the ceramic layer 4. The overlying glaze layer portion 2 is connected to the ceramic layer 4, as shown in FIG.

[0040] Next, a step (S4a) of forming the wiring layer 30 is performed. In this step (S4a), as shown in Fig. 8, the wiring layer 30 is formed on the glaze layer 20. The wiring layer 30 is formed by applying a resinate paste containing a material constituting the wiring layer 30 onto the glaze layer 20 and baking the resinate paste. However, the method of forming the wiring layer 30 is not limited to this.

[0041] The wiring layer 30 thus formed includes a first coated wiring portion 3a that covers the coated glaze layer portion 2. As shown in Fig. 8, the first coated wiring portion 3a is connected to the coated glaze layer portion 2. From a different perspective, the ceramic layer 4, the coated glaze layer portion 2, and the first coated wiring portion 3a are arranged to overlap each other in a plan view of the first surface 10a. In this manner, a protrusion 7 is formed on the first surface 10a.

[0042] Next, a step (S5a) of patterning the wiring layer 30 is performed. In this step (S5a), as shown in FIG. 9, the wiring layer 30 is patterned to form a main body 30a, a plurality of protruding portions 30b, and a plurality of individual electrode portions 31. First, a resist is applied onto the wiring layer 30 (not shown). The resist is applied, for example, by using a roll coater. Next, the resist applied onto the wiring layer 30 is exposed to light. The exposure is performed, for example, by partially irradiating the resist with UV (Ultra Violet) light using a glass mask. The resist in the portion irradiated with UV light is altered. Next, the resist pattern is formed by dissolving and removing the portion of the resist altered by exposure. Next, the wiring layer 30 is etched using the resist pattern as a mask to form a main body 30a, a plurality of protruding portions 30b, and a plurality of individual electrode portions 31 (see FIG. 1). The resist pattern is removed after etching the wiring layer 30. Furthermore, by patterning the wiring layer 30, a recess surrounded by the first electrode portion 32a and the second electrode portion 32b is formed.

[0043] Next, a step (S6a) of forming the heating element 5 is performed. In this step (S6a), the heating element 5 is formed as shown in FIG. 1. First, a conductive paste containing glass and ruthenium oxide particles is applied to a recess formed by being surrounded by the first electrode portion 32a and the second electrode portion 32b. Next, the applied conductive paste is fired. When the heating element 5 is formed in this manner, the spread of the conductive paste is stopped by the side wall surface of the protrusion 7. In other words, the protrusion 7 suppresses the expansion of the width w of the heating element 5. As a result, the height h of the heating element 5 can be increased while adjusting the size of the width w of the heating element 5.

[0044] Next, a step (S7a) of forming a protective glass is performed. In this step (S7a), a heating element 5 is formed to cover the wiring layer 30 and the heating element 5, as shown in FIG.

[0045] <Action and effect> A thermal printhead 100a according to the present disclosure includes an insulating substrate 1, a protrusion 7, and a heating element 5. The insulating substrate 1 has a first surface 10a. The protrusion 7 is formed on the first surface 10a. The heating element 5 has an edge 6. The edge 6 is connected to the protrusion 7. At least a portion of the protrusion 7 includes a ceramic layer 4.

[0046] When the heating element 5 is formed, the protrusions 7 suppress the width w of the heating element 5 from expanding. This is because the formation of the protrusions 7 causes surface tension to act on the conductive paste when the heating element 5 is formed. As a result, the height h of the heating element 5 can be increased while adjusting the size of the width w of the heating element 5. In this way, the printing efficiency of the thermal printhead 100a is improved. In addition, the risk of the heating element 5 interfering with the main body 30a due to a shift in the position at which the heating element 5 is formed is reduced.

[0047] In the thermal printhead 100a, 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 and z directions is the y direction. The heating element 5 and the protrusion 7 extend in the x direction. The protrusion 7 includes a first protrusion 7a and a second protrusion 7b. The second protrusion 7b is spaced apart from the first protrusion 7a in the y direction. In a plan view seen from the z direction, the edge 6 has a first edge 6a and a second edge 6b. The first edge 6a is connected to the first protrusion 7a. The second edge 6b is connected to the second protrusion 7b.

[0048] In this way, the protrusions 7 suppress the expansion of the width w of the heat generating element 5 when the heat generating element 5 is formed. As a result, the height h of the heat generating element 5 can be increased while adjusting the size of the width w of the heat generating element 5.

[0049] In the thermal printhead 100a, the height h of the heat generating element 5 in the z direction is at least 0.03 times the width w of the heat generating element 5 in the y direction.

[0050] In this way, the printing efficiency of the thermal printhead 100a is improved.

[0051] In the thermal printhead 100a, the first convex portion 7a includes a first vertex 71a. The first vertex 71a is the furthest from the first surface 10a. The second convex portion 7b includes a second vertex 71b. The second vertex 71b is the furthest from the first surface 10a. The first edge portion 6a and the second edge portion 6b are each located between the first vertex portion 71a and the second vertex portion 71b in the y direction.

[0052] This prevents the conductive paste from spreading in the y direction beyond the apex 71 of the protrusion 7 when forming the heat generating element 5. In other words, the protrusion 7 prevents the width w of the heat generating element 5 from expanding.

[0053] The thermal printhead 100a includes a glaze layer 20 and a wiring layer 30. The glaze layer 20 is connected to the first surface 10a. The wiring layer 30 is connected to the glaze layer 20. The ceramic layer 4 is connected to the first surface 10a. The glaze layer 20 includes a coated glaze layer portion 2. The coated glaze layer portion 2 covers the ceramic layer 4. The wiring layer 30 includes a first coated wiring portion 3a. The first coated wiring portion 3a covers the coated glaze layer portion 2. The coated glaze layer portion 2 and the first coated wiring portion 3a form a part of the protrusion 7.

[0054] In this way, the protrusions 7 suppress the width w of the heating element 5 from expanding when the heating element 5 is formed. This is because the formation of the protrusions 7 causes surface tension to act on the conductive paste when the heating element 5 is formed. As a result, the height h of the heating element 5 can be increased while adjusting the size of the width w of the heating element 5. In this way, the printing efficiency of the thermal printhead 100a is improved. In addition, the risk of the heating element 5 interfering with the main body 30a due to a shift in the position at which the heating element 5 is formed is reduced.

[0055] In the thermal printhead 100a, the ceramic layer 4 contains particles having a grain size of 2.0 μm or less.

[0056] In this way, the ceramic layer 4 that forms part of the protrusion 7 can be formed.

[0057] In the thermal printhead 100a, the surface roughness of the ceramic layer 4 is greater than the surface roughness of the first surface 10a.

[0058] In this way, the ceramic layer 4 that forms part of the protrusion 7 can be formed.

[0059] In the thermal printhead 100a, the ceramic layer 4 has a melting point equal to or higher than the melting point of the glaze layer 20. The ceramic layer 4 has a melting point equal to or lower than the melting point of the insulating substrate 1.

[0060] In this way, when forming the ceramic layer 4, the ceramic layer 4 that forms part of the protrusions 7 can be formed at a temperature equal to or lower than the melting point of the insulating substrate 1. In addition, when forming the glaze layer 20, the glaze layer 20 can be formed so that the ceramic layer 4 and the glaze layer 20 are not integrated with each other.

[0061] In the thermal printhead 100a, the melting point of the ceramic layer 4 is 1100°C or higher and 1900°C or lower.

[0062] In this way, when forming the ceramic layer 4, the ceramic layer 4 that forms part of the protrusions 7 can be formed at a temperature equal to or lower than the melting point of the insulating substrate 1. In addition, when forming the glaze layer 20, the glaze layer 20 can be formed so that the ceramic layer 4 and the glaze layer 20 are not integrated with each other.

[0063] Embodiment 2 <Thermal print head configuration> Fig. 10 is a schematic partial cross-sectional view of a thermal printhead 100b of embodiment 2. Fig. 10 corresponds to Fig. 2. The thermal printhead 100b shown in Fig. 10 basically has a similar configuration to the thermal printhead 100a shown in Figs. 1 and 2 and can obtain similar effects, but differs in that the ceramic layer 4 is formed on the wiring layer 30.

[0064] The ceramic layer 4 is not formed on the first surface 10a. As shown in Fig. 10, the ceramic layer 4 is located on the opposite side of the glaze layer 20 from the wiring layer 30 in the z direction.

[0065] In the thermal printhead 100b according to the second embodiment, the ceramic layer 4 forms the convex portion 7. From a different perspective, in the thermal printhead 100b according to the second embodiment, the glaze layer 20 does not include the coated glaze layer portion 2 that covers the ceramic layer 4. In other words, the wiring layer 30 does not include the first coated wiring portion 3a that covers the coated glaze layer portion 2. Therefore, in the thermal printhead 100b according to the second embodiment, the coated glaze layer portion 2 and the first coated wiring portion 3a do not form the convex portion 7.

[0066] In this way, the height h of the heating element 5 can be increased while adjusting the width w of the heating element 5. Since the glaze layer 20 and the wiring layer 30 are not formed on the ceramic layer 4, the thermal printhead 100b of the second embodiment is easier to manufacture than the thermal printhead 100a of the first embodiment.

[0067] <Thermal printhead manufacturing method> A method for manufacturing the thermal printhead 100b will now be described. Fig. 11 is a flow chart showing a method for manufacturing the thermal printhead 100b of the second embodiment. Figs. 11 to 16 are schematic partial cross-sectional views showing a step in the method for manufacturing the thermal printhead 100b of the second embodiment.

[0068] First, a process similar to the process shown in Fig. 5 in the manufacturing method of the thermal printhead 100a according to the first embodiment is performed. That is, a process (S1b) of preparing an insulating substrate 1 is performed first. In this process (S1b), an insulating substrate 1 is prepared as shown in Fig. 5.

[0069] Next, a step (S2b) of forming a glaze layer 20 is performed. In this step (S2b), as shown in FIG. 12, the glaze layer 20 is formed on the first surface 10a. Specifically, a paste containing glass is applied onto the first surface 10a. Next, the applied paste is heated. As a result, the solvent in the paste is evaporated and the glass in the paste is bonded to each other, thereby forming the glaze layer 20.

[0070] Next, a step (S3b) of forming the wiring layer 30 is performed. In this step (S3b), as shown in Fig. 13, the wiring layer 30 is formed on the glaze layer 20. The wiring layer 30 is formed by applying a resinate paste containing a material constituting the wiring layer 30 onto the glaze layer 20 and baking the resinate paste. However, the method of forming the wiring layer 30 is not limited to this.

[0071] Next, a step (S4b) of patterning the wiring layer 30 is performed. In this step (S4b), as shown in FIG. 14, the wiring layer 30 is patterned to form a main body 30a, a plurality of protruding portions 30b, and a plurality of individual electrode portions 31. First, a resist is applied onto the wiring layer 30 (not shown). The resist is applied, for example, by using a roll coater. Next, the resist applied onto the wiring layer 30 is exposed to light. The exposure is performed, for example, by partially irradiating the resist with UV (Ultra Violet) light using a glass mask. The resist in the portion irradiated with UV light is altered. Next, the resist pattern is formed by dissolving and removing the portion of the resist altered by exposure. Next, the wiring layer 30 is etched using the resist pattern as a mask to form a main body 30a, a plurality of protruding portions 30b (see FIG. 1), and a plurality of individual electrode portions 31 (see FIG. 1). The resist pattern is removed after etching the wiring layer 30. Furthermore, by patterning the wiring layer 30, a recess surrounded by the first electrode portion 32a and the second electrode portion 32b is formed.

[0072] Next, a step (S5b) of forming the ceramic layer 4 is performed. In this step (S5b), as shown in FIG. 15, the ceramic layer 4 is formed on the wiring layer 30. Specifically, the ceramic layer 4 may be formed using a 3D printer. The ceramic layer 4 may be formed by applying a solvent containing ceramic particles by a dispenser or screen printing. The viscosity of the solvent may be, for example, 60 Pa·S. The heat treatment temperature when forming the ceramic layer 4 may be equal to or lower than the melting point of the insulating substrate 1. The melting point of the insulating substrate 1 is, for example, 2000° C. Therefore, the heat treatment temperature when forming the ceramic layer 4 may be equal to or lower than 1900° C., for example, 1200° C. The ceramic layer 4 formed in this manner becomes the convex portion 7 in the thermal printhead 100b according to the second embodiment.

[0073] After the step (S5b) of forming the ceramic layer 4, a step (S6b) of forming the heating element 5 and a step (S7b) of forming the protective glass are sequentially performed. The step (S6b) of forming the heating element 5 in the method of manufacturing the thermal printhead 100b according to the second embodiment is the same as the step (S6a) of forming the heating element 5 in the thermal printhead 100a according to the first embodiment. The step (S7b) of forming the protective glass in the method of manufacturing the thermal printhead 100b according to the second embodiment is the same as the step (S7a) of forming the protective glass in the thermal printhead 100a according to the first embodiment. In this manner, the thermal printhead 100c shown in FIG. 10 is manufactured.

[0074] <Action and effect> The thermal printhead 100b further includes a glaze layer 20 and a wiring layer 30. The glaze layer 20 is connected to the first surface 10a. The wiring layer 30 is connected to the glaze layer 20. The ceramic layer 4 is located on the opposite side of the wiring layer 30 to the glaze layer 20.

[0075] In this way, the height h of the heating element 5 can be increased while adjusting the width w of the heating element 5. Since the glaze layer 20 and the wiring layer 30 are not formed on the ceramic layer 4, the thermal printhead 100b of the second embodiment is easier to manufacture than the thermal printhead 100a of the first embodiment.

[0076] Embodiment 3 <Thermal print head configuration> Figure 16 is a schematic partial cross-sectional view of a thermal printhead 100c according to embodiment 3. Figure 16 corresponds to Figure 10. The thermal printhead 100c shown in Figure 16 basically has the same configuration as the thermal printhead 100b shown in Figure 10 and can achieve the same effects, but differs in that the ceramic layer 4 is formed on the glaze layer 20.

[0077] The ceramic layer 4 is not formed on the first surface 10a. As shown in Fig. 16, the ceramic layer 4 is directly connected to the glaze layer 20 so as to cover a part of the glaze layer 20. The ceramic layer 4 is not formed in a pair on the glaze layer 20, but is formed alone. The ceramic layer 4 includes a pair of ends. The pair of ends are spaced apart from each other in the y direction.

[0078] 16, a part of the wiring layer 30 is connected to the ceramic layer 4 so as to cover the end of the ceramic layer 4. Specifically, the wiring layer 30 includes a second covered wiring portion 3b. The second covered wiring portion 3b covers a part (end) of the ceramic layer 4.

[0079] The recess is formed by the second coated wiring portion 3b of the first electrode portion 32a, the second coated wiring portion 3b of the second electrode portion 32b, and the ceramic layer 4, with the ceramic layer 4 forming the bottom surface of the recess.

[0080] In this embodiment 3, the height h of the heating element 5 in the z-direction is the distance from the ceramic layer 4 (the bottom surface of the recess formed by being surrounded by the second coated wiring portion 3b of the first electrode portion 32a and the second coated wiring portion 3b of the second electrode portion 32b) to the apex of the heating element 5.

[0081] In the thermal printhead 100c according to the third embodiment, a part (end) of the ceramic layer 4 and the second coated wiring portion 3b form the protrusion 7. From a different perspective, in the thermal printhead 100c according to the third embodiment, the second coated wiring portion 3b forms a part of the protrusion 7.

[0082] In this way, the thermal printhead 100c can be made smaller.

[0083] <Thermal printhead manufacturing method> A method for manufacturing the thermal printhead 100c will now be described. Figure 17 is a flow chart showing the method for manufacturing the thermal printhead 100c of the third embodiment. Figures 18 to 20 are schematic partial cross-sectional views showing a step in the method for manufacturing the thermal printhead 100c of the third embodiment.

[0084] First, in the method for manufacturing the thermal printhead 100b according to the second embodiment, the step (S1c) of preparing the insulating substrate 1 shown in Fig. 5 and the step (S2c) of forming the glaze layer 20 shown in Fig. 12 are performed. That is, the step (S1c) of preparing the insulating substrate 1 is performed first. In this step (S1c), the insulating substrate 1 is prepared as shown in Fig. 5.

[0085] Next, a step (S2c) of forming a glaze layer 20 is performed. In this step (S2c), as shown in FIG. 12, the glaze layer 20 is formed on the first surface 10a. Specifically, a paste containing glass is applied onto the first surface 10a. Next, the applied paste is heated. As a result, the solvent in the paste is evaporated and the glass in the paste is bonded to each other, thereby forming the glaze layer 20.

[0086] Next, a step (S3c) of forming a ceramic layer 4 is performed. In this step (S3c), as shown in FIG. 18, the ceramic layer 4 is formed on the glaze layer 20. Specifically, the ceramic layer 4 may be formed using a 3D printer. The ceramic layer 4 may be formed by applying a solvent containing ceramic particles by a dispenser or screen printing. The viscosity of the solvent may be, for example, 60 Pa·S. The heat treatment temperature when forming the ceramic layer 4 may be equal to or lower than the melting point of the insulating substrate 1. The melting point of the insulating substrate 1 is, for example, 2000° C. Therefore, the heat treatment temperature when forming the ceramic layer 4 may be equal to or lower than 1900° C., for example, 1200° C. The end of the ceramic layer 4 formed in this way becomes a part of the convex portion 7 in the thermal printhead 100b according to the second embodiment.

[0087] Next, a step (S4c) of forming the wiring layer 30 is performed. In this step (S4c), as shown in Fig. 19, the wiring layer 30 is formed on the glaze layer 20 and the ceramic layer 4. The wiring layer 30 is formed by applying a resinate paste containing a material constituting the wiring layer 30 onto the glaze layer 20 and firing the resinate paste. However, the method of forming the wiring layer 30 is not limited to this.

[0088] Next, a step (S5c) of patterning the wiring layer 30 is performed. In this step (S5c), as shown in FIG. 20, the wiring layer 30 is patterned to form a main body 30a, a plurality of protruding portions 30b, and a plurality of individual electrode portions 31. First, a resist is applied onto the wiring layer 30 (not shown). The resist is applied, for example, by using a roll coater. Next, the resist applied onto the wiring layer 30 is exposed to light. The exposure is performed, for example, by partially irradiating the resist with UV (Ultra Violet) light using a glass mask. The resist in the portion irradiated with UV light is altered. Next, the resist pattern is formed by dissolving and removing the portion of the resist altered by exposure. Next, the wiring layer 30 is etched using the resist pattern as a mask to form a main body 30a, a plurality of protruding portions 30b (see FIG. 1), and a plurality of individual electrode portions 31 (see FIG. 1). The resist pattern is removed after etching the wiring layer 30. Furthermore, a recess surrounded by the first electrode portion 32a and the second electrode portion 32b is formed by patterning the wiring layer 30. In the thermal printhead 100c according to the third embodiment, the recess is formed by the first electrode portion 32a, the second electrode portion 32b, and the ceramic layer 4 such that the ceramic layer 4 forms the bottom surface of the recess.

[0089] The wiring layer 30 thus formed includes a second coated wiring portion 3b that covers a part of the ceramic layer 4. As shown in Fig. 20, the second coated wiring portion 3b is connected to the ceramic layer 4. From a different perspective, the end of the ceramic layer 4 and the second coated wiring portion 3b are arranged to overlap in a plan view of the first surface 10a. In this manner, a protrusion 7 is formed on the first surface 10a.

[0090] After the step (S5c) of patterning the wiring layer 30, the step (S6c) of forming the heating element 5 and the step (S7c) of forming the protective glass are performed in sequence. The step (S6c) of forming the heating element 5 in the method of manufacturing the thermal printhead 100c according to the third embodiment is the same as the step (S6b) of forming the heating element 5 in the thermal printhead 100b according to the second embodiment. The step (S7c) of forming the protective glass in the method of manufacturing the thermal printhead 100c according to the third embodiment is the same as the step (S7b) of forming the protective glass in the thermal printhead 100b according to the second embodiment. In this manner, the thermal printhead 100c shown in FIG. 16 is manufactured.

[0091] <Action and effect> The thermal printhead 100c further includes a glaze layer 20 and a wiring layer 30. The glaze layer 20 is connected to the first surface 10a. The wiring layer 30 is connected to the glaze layer 20. The ceramic layer 4 is connected to the glaze layer 20. The wiring layer 30 includes a second coated wiring portion 3b. The second coated wiring portion 3b covers a portion of the ceramic layer 4. The second coated wiring portion 3b forms a portion of the protrusion 7.

[0092] In this way, the thermal printhead 100c can be made smaller.

[0093] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. Unless inconsistent, at least two of the embodiments disclosed herein may be combined. The basic scope of the present disclosure is indicated by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0094] The present disclosure includes the following aspects. (Appendix 1) an insulating substrate having a first surface; A protrusion formed on the first surface; a heating element having an edge; The edge portion is connected to the protrusion, At least a portion of the protrusion includes a ceramic layer. (Appendix 2) A direction perpendicular to the first surface is defined as a z direction, The direction perpendicular to the z direction is defined as the x direction, If the direction perpendicular to the x direction and the z direction is the y direction, the heating element and the protrusion extend in the x direction, the protrusion includes a first protrusion and a second protrusion disposed apart from the first protrusion in a y direction, A thermal printhead as described in Appendix 1, wherein, when viewed in a planar view from the z direction, the edge portion has a first edge portion connected to the first convex portion and a second edge portion connected to the second convex portion. (Appendix 3) 3. The thermal printhead of claim 2, wherein the height of the heating element in the z direction is at least 0.03 times the width of the heating element in the y direction. (Appendix 4) the first protrusion includes a first vertex portion that is farthest from the first surface, the second protrusion includes a second vertex portion that is farthest from the first surface, 4. The thermal printhead of claim 2, wherein each of the first edge portion and the second edge portion is located between the first vertex portion and the second vertex portion in the y direction. (Appendix 5) a glaze layer connected to the first surface; A wiring layer connected to the glaze layer, the ceramic layer is connected to the first surface; the glaze layer includes a coating glaze layer portion covering the ceramic layer; The wiring layer includes a first coated wiring portion that covers the coated glaze layer portion, 5. The thermal printhead according to claim 2, wherein the covering glaze layer portion and the first covered wiring portion form part of the convex portion. (Appendix 6) a glaze layer connected to the first surface; A wiring layer connected to the glaze layer, 5. The thermal printhead of claim 2, wherein the ceramic layer is located on the opposite side of the glaze layer from the wiring layer. (Appendix 7) a glaze layer connected to the first surface; A wiring layer connected to the glaze layer, the ceramic layer is connected to the glaze layer; the wiring layer includes a second coated wiring portion that covers a part of the ceramic layer, 5. The thermal printhead according to claim 2, wherein the second coated wiring portion forms a part of the protrusion. (Appendix 8) 8. The thermal printhead of claim 1, wherein the ceramic layer contains particles having a particle size of 2.0 μm or less. (Appendix 9) 9. The thermal printhead of claim 1, wherein the ceramic layer has a surface roughness greater than a surface roughness of the first surface. (Appendix 10) 10. The thermal printhead of claim 1, wherein the melting point of the ceramic layer is equal to or higher than the melting point of the glaze layer and equal to or lower than the melting point of the insulating substrate. (Appendix 11) 11. The thermal printhead of claim 1, wherein the ceramic layer has a melting point of 1100° C. or higher and 1900° C. or lower. [Explanation of symbols]

[0095] 1 insulating substrate, 2 coated glaze layer portion, 3a first coated wiring portion, 3b second coated wiring portion, 4 ceramic layer, 5 heating element, 6 edge portion, 6a first edge portion, 6b second edge portion, 7 convex portion, 7a first convex portion, 7b second convex portion, 10a first surface, 10b second surface, 10c first side surface, 10d second side surface, 20 glaze layer, 30 wiring layer, 30a main body portion, 30b protrusion portion, 31 individual electrode portion, 31a tip portion, 31b pad, 32a first electrode portion, 32b second electrode portion, 71 apex, 71a first apex portion, 71b second apex portion, 100a, 100b, 100c thermal print head, w width, h height.

Claims

1. an insulating substrate having a first surface; A convex portion formed on the first surface; a heating element having an edge; The edge portion is connected to the protrusion, At least a portion of the protrusion includes a ceramic layer.

2. A direction perpendicular to the first surface is defined as a z direction, A direction perpendicular to the z direction is defined as an x ​​direction, If the direction perpendicular to the x direction and the z direction is the y direction, the heating element and the protrusion extend in the x direction, The convex portion includes a first convex portion and a second convex portion disposed apart from the first convex portion in a y direction, 2. The thermal printhead of claim 1, wherein, in a planar view from the z direction, the edge portion has a first edge portion connected to the first convex portion and a second edge portion connected to the second convex portion.

3. The thermal printhead of claim 2 , wherein a height of the heating element in the z direction is at least 0.03 times a width of the heating element in the y direction.

4. the first protrusion includes a first vertex portion that is farthest from the first surface, the second convex portion includes a second vertex portion that is farthest from the first surface, The thermal printhead of claim 2 , wherein each of the first edge and the second edge is located between the first vertex and the second vertex in the y direction.

5. a glaze layer connected to the first surface; A wiring layer connected to the glaze layer, the ceramic layer is connected to the first surface; the glaze layer includes a coating glaze layer portion covering the ceramic layer; The wiring layer includes a first coated wiring portion that covers the coated glaze layer portion, The thermal printhead according to claim 2 , wherein the covering glaze layer portion and the first covered wiring portion form a part of the convex portion.

6. a glaze layer connected to the first surface; A wiring layer connected to the glaze layer, 5. The thermal printhead according to claim 2, wherein the ceramic layer is located on an opposite side of the wiring layer to the glaze layer.

7. a glaze layer connected to the first surface; A wiring layer connected to the glaze layer, the ceramic layer is connected to the glaze layer; the wiring layer includes a second coated wiring portion that covers a portion of the ceramic layer, The thermal printhead according to claim 2 , wherein the second coated wiring portion forms a part of the protrusion.

8. The thermal printhead of claim 1 , wherein the ceramic layer includes particles having a grain size of 2.0 μm or less.

9. The thermal printhead according to claim 1 , wherein a surface roughness of the ceramic layer is greater than a surface roughness of the first surface.

10. 5. The thermal printhead according to claim 1, wherein the melting point of the ceramic layer is equal to or higher than the melting point of the glaze layer and equal to or lower than the melting point of the insulating substrate.

11. 5. The thermal printhead according to claim 1, wherein the ceramic layer has a melting point of 1100[deg.] C. or higher and 1900[deg.] C. or lower.

Images