Thermal printhead and method of manufacturing the same
By employing a structure of first and second metal layers in the thermal printhead, combined with an insulating layer and a heating resistor layer of low-temperature co-fired ceramic material, the problem of coarse wiring width in screen printing is solved, achieving a high-resolution and low-cost manufacturing method.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ROHM CO LTD
- Filing Date
- 2022-01-27
- Publication Date
- 2026-07-31
AI Technical Summary
In existing technologies, when forming wiring using screen printing, the flow of metal paste causes the wiring width to become thicker, making it difficult to meet the requirements of high resolution.
The structure employs a first and second metal layer formed on a substrate. Wiring is formed on the insulating layer of a low-temperature co-fired ceramic material by screen printing, and a heating resistor layer is formed on the insulating layer. Multiple heating elements are used to selectively heat and form printed dots.
It effectively suppressed the flow of metal paste, achieved finer wiring width, improved the resolution of the thermal printhead, simplified the manufacturing process, and reduced manufacturing costs.
Smart Images
Figure CN114801504B_ABST
Abstract
Description
Technical Field
[0001] This embodiment relates to a thermal printhead and a method for manufacturing the same. Background Technology
[0002] In thermal printheads, it is known to generate heat by making the wiring connected to the heating resistor conductive. For example, it is known to use screen printing to form the wiring.
[0003] Existing technical documents
[0004] Patent documents
[0005] Patent document 1: Japanese Patent Application Publication No. 2008-207439. Summary of the Invention
[0006] The problem the invention aims to solve
[0007] However, in recent years, thermal printheads have been required to improve the resolution of wire width. Therefore, when using screen printing to form wires, the resolution deteriorates and the wire width becomes thicker due to the flow of the metal paste.
[0008] The present invention provides a thermal printhead capable of suppressing the flow of metal paste and forming a finer wiring width, and a method thereof for manufacturing the same.
[0009] Technical means for solving problems
[0010] According to one embodiment of this invention, a thermal printhead is provided, comprising: a substrate; a first heat storage layer disposed on the substrate; wiring having a first metal layer disposed on the first heat storage layer, and a second metal layer disposed on the first heat storage layer and spaced apart from the first metal layer; and a heating resistor layer disposed on the first heat storage layer and electrically connected to the first metal layer and the second metal layer.
[0011] According to another aspect of this embodiment, a method for manufacturing a thermal printhead is provided, comprising: a step of forming a first heat storage layer on a substrate; a step of forming wiring on the first heat storage layer; and a step of forming a heating resistor layer electrically connected to the wiring on the first heat storage layer.
[0012] Invention Effects
[0013] According to the present invention, a thermal printhead capable of suppressing the flow of metal paste and capable of forming a finer wiring width is provided, and a method thereof for manufacturing the same is provided. Attached Figure Description
[0014] Figure 1 This is a schematic plan view of the thermal printhead of the first embodiment.
[0015] Figure 2 yes Figure 1 An enlarged view of the periphery A of the heating resistor layer shown.
[0016] Figure 3 It will be along Figure 2 An enlarged diagram illustrating the schematic cross-sectional structure of line B1-B1.
[0017] Figure 4A It will be along Figure 2 An enlarged diagram illustrating the schematic cross-sectional structure of line D1-D1.
[0018] Figure 4B It will be along Figure 2 An enlarged diagram illustrating the schematic cross-sectional structure of line E1-E1.
[0019] Figure 5A It is along Figure 2 A schematic cross-sectional view of the D1-D1 line, and an explanatory diagram showing the flow of the molten metal. (Part 1)
[0020] Figure 5B It is along Figure 2 A schematic cross-sectional view of the D1-D1 line, and an explanatory diagram showing the flow of the metal paste. (Part Two)
[0021] Figure 6 It will be along Figure 2 An enlarged diagram illustrating the schematic cross-sectional structure of line C1-C1.
[0022] Figure 7 This is a flowchart of the main processes in manufacturing the thermal printhead according to the first embodiment.
[0023] Figure 8A This is a cross-sectional view showing one step of the manufacturing process of the thermal printhead according to the first embodiment.
[0024] Figure 8B It means to continue Figure 8A A cross-sectional view of one of the processes.
[0025] Figure 8C It means to continue Figure 8B A cross-sectional view of one of the processes.
[0026] Figure 8D It means to continue Figure 8C A cross-sectional view of one of the processes.
[0027] Figure 9 yes Figure 1 A2 is an enlarged view of the periphery A of the heating resistor layer shown.
[0028] Figure 10 It will be along Figure 9 An enlarged diagram illustrating the schematic cross-sectional structure of line B2-B2.
[0029] Figure 11 It will be along Figure 9 An enlarged diagram illustrating the schematic cross-sectional structure of line C2-C2.
[0030] Figure 12 yes Figure 1 A magnified view A3 of the periphery A of the heating resistor layer shown.
[0031] Figure 13 It will be along Figure 12 An enlarged diagram illustrating the schematic cross-sectional structure of line B3-B3.
[0032] Figure 14 It will be along Figure 12 An enlarged diagram illustrating the schematic cross-sectional structure of line C3-C3.
[0033] Figure 15 This is a flowchart of the main processes in manufacturing the thermal printhead according to the second embodiment.
[0034] Figure 16A This is a cross-sectional view showing one step of the manufacturing process of the thermal printhead according to the second embodiment.
[0035] Figure 16B It means to continue Figure 16A A cross-sectional view of one of the processes.
[0036] Explanation of reference numerals in the attached figures
[0037] 1 substrate
[0038] 2 First heat storage layer
[0039] 3 common electrodes
[0040] 4. Drive circuit
[0041] 5 wiring
[0042] 51 First Metal Layer
[0043] 52 Second metal layer
[0044] 6 heating resistance layer
[0045] 61 Fever Section
[0046] 62 gaps
[0047] 7 connectors
[0048] 8 protective layers
[0049] 9 Second thermal storage layer
[0050] 10 thermal printheads
[0051] 12 glaze layers
[0052] 101 First Current Path
[0053] 201 First front end
[0054] 202 Second front end
[0055] 203 Third front end
[0056] 204 Fourth front end
[0057] 205 Fifth Front End
[0058] 206 Sixth Anterior End
[0059] 207 Seventh Front End Detailed Implementation
[0060] Next, this embodiment will be described with reference to the accompanying drawings. In the drawings described below, the same or similar components are labeled with the same or similar reference numerals. However, it should be noted that the drawings are schematic illustrations, and the thickness and planar dimensions of each component may differ from reality. Therefore, the specific thickness or dimensions should be determined with reference to the following description. Furthermore, this also includes parts in the drawings where there are differences in dimensional relationships or proportions between them.
[0061] Furthermore, the embodiments shown below are illustrative of apparatus or methods for embodying technical ideas, and are not intended to specify the material, shape, structure, or arrangement of each component. Various modifications can be made to this embodiment within the scope of the claims.
[0062] The thermal printhead 10 of the first embodiment will be described using the accompanying drawings. Figure 1 This is a schematic plan view of the thermal printhead 10 according to the first embodiment.
[0063] Figure 2 yes Figure 1 An enlarged view of the periphery A of the heating resistor layer 6 shown. Figure 3 It will be along Figure 2 An enlarged diagram illustrating the schematic cross-sectional structure of line B1-B1. Furthermore, Figure 1 The device surface shown in the plan view is designated as the XY plane, and the direction perpendicular to the XY plane is designated as the Z-axis. Figure 3This is the YZ plane viewed from the X direction. That is, the main scanning direction of substrate 1 is taken as the X direction, the sub-scanning direction as the Y direction, and the thickness direction as the Z direction. In the following description, the main scanning direction will be referred to as the X direction, the sub-scanning direction as the Y direction, and the thickness direction as the Z direction. Furthermore, the X direction will also be referred to as the first direction, the Y direction as the second direction, and the Z direction as the third direction.
[0064] Figure 4A It will be along Figure 2 An enlarged diagram illustrating the schematic cross-sectional structure of line D1-D1. Figure 4B It will be along Figure 2 An enlarged diagram illustrating the schematic cross-sectional structure of line E1-E1. Furthermore, Figure 4A and Figure 4B This is the XZ plane viewed from the Y direction, which is the second direction.
[0065] Figure 5A and Figure 5B It is along Figure 2 A schematic cross-sectional view of the D1-D1 line and an explanatory diagram showing the flow of the metal paste. Figure 6 It will be along Figure 2 An enlarged diagram illustrating the schematic cross-sectional structure of line C1-C1. Furthermore, Figure 5A , Figure 5B and Figure 6 This is the XZ plane viewed from the Y direction.
[0066] [First Implementation Method]
[0067] The thermal printhead 10 of the first embodiment is as follows: Figure 1 , Figure 2 and Figure 3 The diagram shows: a substrate 1; a first heat storage layer 2 disposed on the substrate 1; a common electrode 3 disposed on the first heat storage layer 2; a wiring 5 electrically connected to the common electrode 3; a heating resistor layer 6 disposed on the first heat storage layer 2 and electrically connected to the wiring 5; a drive circuit 4 electrically connected to the wiring 5 for controlling the energization of the heating resistor layer 6 to generate heat; a connector 7 electrically connecting external terminals to the common electrode 3 and the drive circuit 4; and a protective layer 8 disposed on the wiring 5 and the heating resistor layer 6. Figure 1 and Figure 2 omitted).
[0068] Substrate 1 as Figure 1As shown, when viewed from above, the device surface on substrate 1 is a rectangular electrical insulating material. The insulating material can be formed, for example, from alumina ceramics or low-temperature co-fired ceramics (LTCC). Alumina ceramics are also known as high-temperature co-fired ceramics (HTCC).
[0069] The size of the substrate 1 is not limited. For example, the size of the X direction, which is the first direction, is 50 mm to 150 mm, the size of the Y direction, which is the second direction, is 2.0 mm to 10.0 mm, and the size of the Z direction, which is the third direction, is 500 μm to 1 mm, preferably 700 μm to 800 μm.
[0070] like Figure 2 As shown, the first heat storage layer 2 is an insulating material with low thermal conductivity and is disposed on the substrate 1. The first heat storage layer 2 is, for example, a green sheet. The green sheet is a sheet that is flexible before firing. The green sheet is an insulating layer formed from a low-temperature co-fired ceramic (LTCC) material containing glass powder and ceramic powder. The first heat storage layer 2 temporarily stores a portion of the heat generated by the heating resistor layer 6.
[0071] Figure 3 The thickness of the first heat storage layer 2 in the Z direction is not particularly limited, for example, it is about 100μm to 150μm.
[0072] Common electrode 3, as Figure 1 As shown, it is disposed on the first heat storage layer 2 and electrically connected to the connector 7 and the wiring 5. The common electrode 3 contains metal particles, such as copper (Cu), silver (Ag), palladium (Pd), iridium (In), platinum (Pt), and gold (Au). From the viewpoint of the metal's ionization tendency, copper (Cu), silver (Ag), platinum (Pt), and gold (Au) are preferred. The thickness of the common electrode 3 in the Z direction is not particularly limited, for example, it is around 0.2 μm to 0.8 μm.
[0073] Wiring 5 Figure 1 , Figure 2 and Figure 3 As shown, it is disposed on the first heat storage layer 2 and electrically connected to the common electrode 3 and the heating resistor layer 6. In addition, the wiring 5 is electrically connected to the drive circuit 4 via the heating resistor layer 6.
[0074] like Figure 2 , Figure 3 As shown, the wiring 5 has: a first metal layer 51 disposed on the first heat storage layer 2; and a second metal layer 52 disposed on the first heat storage layer 2 at a distance from the first metal layer 51.
[0075] As part of wiring 5, the first metal layer 51 is as follows Figure 1 , Figure 2 As shown, it is electrically connected to the common electrode 3.
[0076] First metal layer 51 Figure 2 As shown, the end of the first metal layer 51 in the X direction is referred to as the first front end 201. Additionally, as... Figure 2 , Figure 4A As shown, the end of the first metal layer 51 that extends in the Y direction intersecting with the first front end 201 is referred to as the second front end 202.
[0077] like Figure 2 , Figure 3 As shown, the front end of the first metal layer 51 extending from the first front end portion 201 in the Y direction is referred to as the third front end portion 203. Additionally, as... Figure 2 , Figure 4A As shown, the end of the first metal layer 51 in the Y direction opposite to the second front end 202 is referred to as the fourth front end 204. Furthermore, the length of the first metal layer 51 in the X direction from the second front end 202 to the fourth front end 204 is referred to as the wiring width of the first metal layer 51. The wiring width of the first metal layer 51 is as follows... Figure 4A The diagram shows L1.
[0078] As part of wiring 5, the second metal layer 52 is as follows Figure 1 , Figure 2 As shown, it is electrically connected to drive circuit 4.
[0079] like Figure 2 , Figure 4B As shown, the end of the second metal layer 52 extending in the Y direction is referred to as the fifth front end 205. Figure 2 , Figure 3 As shown, the end of the second metal layer 52 opposite to the third front end 203 of the first metal layer 51 is referred to as the sixth front end 206. Additionally, as... Figure 2 , Figure 4B As shown, the Y-direction end of the second metal layer 52 opposite to the fifth front end 205 is referred to as the seventh front end 207. Furthermore, the X-direction length of the second metal layer 52 from the fifth front end 205 to the seventh front end 207 is referred to as the wiring width of the second metal layer 52. The second metal wiring width is as follows... Figure 4B The diagram shows L1.
[0080] First metal layer 51 Figure 3 As shown, the cross-section of the third front end 203 in the Y direction is arc-shaped.
[0081] First metal layer 51 Figure 4AAs shown, the cross-sections of the second front end portion 202 and the fourth front end portion 204 in the X direction are arc-shaped.
[0082] Second metal layer 52 Figure 3 As shown, the cross-section of the sixth front end 206 in the Y direction is arc-shaped.
[0083] Second metal layer 52 Figure 4B As shown, the cross-sections of the fifth front end 205 and the seventh front end 207 in the X direction are arc-shaped.
[0084] Here, the wiring width of the first metal layer 51 will be explained. The first metal layer 51 disposed on the first heat storage layer 2 is disposed, for example, by screen printing. Figure 5A This describes the structure of the thermal printhead in this embodiment. Figure 5B For example, a comparative example is a case where a glaze layer 12 with glass as the main component is formed on a substrate 1.
[0085] Metal paste 22 becomes the first metal layer 51 Figure 5A As shown, the screen is moved on the screen mask 21 by a squeegee 23. Furthermore, the first metal layer 51 forms a wiring pattern through the openings in the screen mask 21. At this time, the first heat storage layer 2, being an insulating layer formed from a low-temperature co-fired ceramic (LTCC) material containing glass powder and ceramic powder, absorbs the solvent from the metal paste 22. That is, the wiring width of the formed first metal layer 51 becomes L1 relative to the wiring width L2 of the first metal layer 51 on the screen mask 21.
[0086] As a comparative example, the glaze layer 12 on substrate 1 is as follows: Figure 5B As shown, since it does not absorb the solvent of the metal paste 22, the metal paste 22 that forms the first metal layer 51 flows in the main scanning direction. That is, the wiring width of the first metal layer 51 after formation becomes L3 relative to the wiring width L2 of the first metal layer 51 of the screen mask 21.
[0087] Drive circuit 4, as shown Figure 1 , Figure 2 As shown, it is disposed on the first heat storage layer 2 and electrically connected to the second metal layer 52, which is part of the wiring 5, and the connector 7. Furthermore, the drive circuit 4 controls the heating resistor layer 6 to generate heat by energizing each pair of the first metal layer 51 and the second metal layer 52.
[0088] Heating resistive layer 6 Figure 1 , Figure 2 and Figure 3 As shown, it extends in the X direction and is configured to cover at least a portion of the first metal layer 51. Additionally, the heating resistor layer 6 is configured to cover at least a portion of the second metal layer 52.
[0089] Heating resistive layer 6 Figure 2 and Figure 3 As shown, it is positioned in the Y direction between the first metal layer 51 and the second metal layer 52. Additionally, the heating resistor layer 6 is as follows... Figure 2 , Figure 6 The diagram shows a heating element 61. That is, the heating resistive layer 6 is as follows: Figure 2 , Figure 6 As shown, in the direction of the device surface on the substrate 1 when viewed from above, i.e. the Z direction, there are multiple heat-generating parts 61 arranged along the X direction.
[0090] Multiple heating elements 61 are energized in four separate ways by a drive circuit, thereby selectively heating up. That is, one printing dot is formed by the heating of one heating element 61.
[0091] Heating resistive layer 6 Figure 6 The diagram shows multiple slits 62. The slits 62 are located between adjacent heating elements 61 and are formed by a protective layer 8. Furthermore, the slits 62 are as follows... Figure 2 As shown, when viewed from the Z direction, it is disposed between adjacent first metal layer 51 and second metal layer 52.
[0092] Therefore, the multiple heating elements 61 have a structure that separates them from each other. That is, the current flowing in one heating element 61 is as follows: Figure 2 As shown, for example, current flows from the first metal layer 51 through the heating resistor layer 6 to the second metal layer 52. In the following description, the current path flowing in the one heating element 61 will be referred to as the first current path 101.
[0093] Connector 7, etc. Figure 1 As shown, it is disposed on substrate 1 and electrically connected to external terminals, drive circuit 4 and common electrode 3.
[0094] Protective layer 8 Figure 3 As shown, a glass layer is formed as a protective film covering the wiring 5 and the heating resistor layer 6.
[0095] Next, an example of a method for manufacturing the thermal printhead 10 according to the first embodiment will be described. In manufacturing the thermal printhead 10 of the first embodiment, a semiconductor process is used.
[0096] Figure 7 This is a flowchart illustrating the main processes involved in manufacturing the thermal printhead 10 according to the first embodiment. Figures 8A to 8D yes Figure 7 The cross-sectional structure along line B1-B1 of the periphery A of the heating resistor layer 6 in each process is shown. That is, Figures 8A to 8D This is the YZ plane viewed from the X direction.
[0097] (S1-1) First, in Figure 7 In step S1 shown, a first heat storage layer 2 is formed on the substrate 1. For example... Figure 8A As shown, substrate 1 is prepared. Here, substrate 1 is, for example, an alumina ceramic substrate.
[0098] (S1-2) Next, as Figure 8B As shown, a first heat storage layer 2 is formed on the substrate 1. Here, the first heat storage layer 2 is, for example, a green sheet of a low-temperature co-fired ceramic material containing glass powder and ceramic powder. The first heat storage layer 2 can also be formed by laminating and stacking a green sheet that has already been formed into a sheet shape onto the substrate 1. Alternatively, a slurry (paste) of a low-temperature co-fired ceramic material containing glass powder and ceramic powder can be applied to the substrate 1 and dried.
[0099] (S2-1) in Figure 7 In step S2, as shown, wiring 5 is formed on the first heat storage layer 2. Here, wiring 5 has a first metal layer 51 and a second metal layer 52 as part of wiring 5. Figure 8C As shown, a first metal layer 51 and a second metal layer 52 are formed on the first heat storage layer 2. The formation of the first metal layer 51 and the second metal layer 52 is, for example, achieved using screen printing.
[0100] (S2-2) Next, the first metal layer 51 and the second metal layer 52 are formed by printing the metal paste 22, drying it, and firing it at a temperature of 800°C to 850°C. That is, the green sheet is fired simultaneously during the firing process of forming the first metal layer 51 and the second metal layer 52.
[0101] The thickness of the first metal layer 51 and the second metal layer 52 in the Z direction is approximately 0.2 μm to 0.8 μm. Alternatively, the thickness of the first metal layer 51 and the second metal layer 52 in the Z direction can be formed by screen printing multiple times.
[0102] That is, since the first metal layer 51 and the second metal layer 52 are formed by screen printing, therefore, as Figure 8C As shown, in the Y direction, the cross-sections of the third front end portion 203 and the sixth front end portion 206 are arc-shaped.
[0103] Similarly, the first metal layer 51 is as follows Figure 4A As shown, the cross-sections of the second front end portion 202 and the fourth front end portion 204 in the X direction are arc-shaped. Additionally, the second metal layer 52... Figure 4B As shown, the cross-sections of the fifth front end 205 and the seventh front end 207 in the X direction are arc-shaped.
[0104] The wiring width of the first metal layer 51 and the second metal layer 52, in the X direction, for example... Figure 4Aand Figure 4B The L1 shown is approximately 50 μm to 100 μm. In addition, the distance between wiring 5 and adjacent wiring 5 in the X direction (the space between wirings) is, for example, approximately 70 μm to 120 μm.
[0105] (S3-1) in Figure 7 In step S3 shown, a heating resistor layer 6 is formed on the first heat storage layer 2. Here, the heating resistor layer 6 is formed, for example, using screen printing. Furthermore, the heating resistor layer 6 is as follows... Figure 1 , Figure 2 and Figure 8D As shown, the paste of the heating resistor layer 6 is printed in a strip shape at designated locations on the heat storage layer 2, covering a portion of the wiring 5. Additionally, the heating resistor layer 6 is as follows... Figure 2 As shown, it has multiple heating elements 61, and a heating element 61 is formed in each of each wiring 5.
[0106] (S3-2) Next, the heating resistor layer 6 is formed by drying the printed paste and firing it at 800°C to 850°C. The thickness of the heating resistor layer 6 in the Z direction is, for example, 4μm to 6μm.
[0107] The paste of the heating resistor layer 6 contains a conductive material and glass. The conductive material of the heating resistor layer 6 can be, for example, ruthenium oxide (IV), tantalum nitride (TaN), tantalum (Ta), and silver palladium (Ag / Pd).
[0108] In the manufacturing process of the thermal printhead 10 of the first embodiment, the process after the formation of the heating resistor layer 6 is known, so the description of the process is omitted.
[0109] The thermal printhead 10 of the first embodiment is completed through the above procedures.
[0110] Next, the function of the thermal printhead 10 in the first embodiment will be explained.
[0111] like Figure 5A As shown, the first heat storage layer 2 formed on the substrate 1 absorbs the solvent of the metal paste 22 during the formation of the first metal layer 51 and the second metal layer 52. Therefore, the flow of the metal paste 22 can be suppressed. That is, the resolution of the wiring pattern of the screen mask 21 is improved, so the wiring width of the first metal layer 51 and the second metal layer 52 can be formed to be finer.
[0112] Furthermore, when using a green sheet, the first heat storage layer 2 formed on the substrate 1 can suppress the manufacturing time because the firing process of the first heat storage layer 2 and the wiring 5 and the first heat storage layer 2 are fired simultaneously in the wiring 5 formation process.
[0113] Since no photolithography-based exposure apparatus is used, there are no resist coating and etching processes. Therefore, the manufacturing time can be reduced. In addition, screen printing is used in steps S2 and S3, which simplifies the manufacturing process and reduces manufacturing costs.
[0114] And, as Figure 7 As shown, in the process of forming the wiring 5 and the heating resistor layer 6, the front ends of the first metal layer 51 and the second metal layer 52, which are part of the wiring 5, are formed by screen printing. Figure 4A , Figure 4B The structure shown is formed in an arc shape. Furthermore, the heating resistance layer 6 is as follows... Figure 2 , Figure 6 As shown, the circuit is configured with multiple heating elements 61. Thus, the multiple heating elements 61 are partially energized by the drive circuit 4, thereby selectively heating. That is, the heating of one heating element 61 can form one printing dot.
[0115] [Modifications of the First Embodiment]
[0116] Next, a modified example of the thermal printhead 10 of the first embodiment will be described. In the following description, the modified example of the thermal printhead 10 of the first embodiment will be referred to as a modified example of the first embodiment.
[0117] Figure 9 yes Figure 1 A2 is an enlarged view of the periphery A of the heating resistor layer 6 shown. Figure 10 It will be along Figure 9 An enlarged diagram illustrating the schematic cross-sectional structure of line B2-B2. Figure 10 This is the YZ plane viewed from the X direction. Figure 11 It will be along Figure 9 An enlarged diagram illustrating the schematic cross-sectional structure of line C2-C2. Figure 11 This is the XZ plane viewed from the Y direction.
[0118] Wiring 5 in a variation of the first embodiment is as follows: Figure 9 As shown, it has a third metal layer 53 and a fourth metal layer 54. The third metal layer 53, as part of the wiring 5, is as follows... Figure 1 , Figure 9 As shown, it is electrically connected to the common electrode 3. Additionally, the fourth metal layer 54, as part of the wiring 5, is as follows... Figure 1 , Figure 9 As shown, it is electrically connected to drive circuit 4.
[0119] The first embodiment differs from its variant in that, in the sub-scanning direction, the first metal layer 51 and the second metal layer 52 of the first embodiment are opposite to each other, while in the variant of the first embodiment, the third metal layer 53 and the fourth metal layer 54 are alternately arranged in the X direction. The other structures are the same as those of the first embodiment.
[0120] That is, the current flowing in the heating resistor layer 6 of the modified embodiment of the first embodiment flows, for example, from both the fourth metal layer 54 and the adjacent third metal layer 53. In the following description, the current path flowing from both the fourth metal layer 54 and the adjacent third metal layer 53 to the heating resistor layer 6 is referred to as the second current path 102.
[0121] Third metal layer 53 Figure 9 As shown, the end of the third metal layer 53 in the X direction is referred to as the eighth front end 208. Additionally, as... Figure 9 As shown, the end of the third metal layer 53 that extends in the Y direction intersecting with the eighth front end 208 is referred to as the ninth front end 209.
[0122] like Figure 9 , Figure 10 As shown, the tip of the end of the third metal layer 53 extending in the Y direction from the eighth tip 208 is referred to as the tenth tip 210. Additionally, as... Figure 9 , Figure 11 As shown, the Y-direction end of the third metal layer 53 opposite to the ninth front end 209 is referred to as the eleventh front end 211. Furthermore, the X-direction length of the third metal layer 53 from the ninth front end 209 to the eleventh front end 211 is referred to as the wiring width of the third metal layer 53. The wiring width of the third metal layer 53 is as follows... Figure 11 The diagram shows L1.
[0123] like Figure 9 , Figure 11 As shown, the Y-direction end of the fourth metal layer 54 opposite to the eleventh front end 211 is referred to as the twelfth front end 212. The front end of the fourth metal layer 54 opposite to the third metal layer 53 is referred to as the thirteenth front end 213. Furthermore, the Y-direction end of the fourth metal layer 54 opposite to the twelfth front end 212 is referred to as the fourteenth front end 214. In addition, the X-direction length of the fourth metal layer 54 from the twelfth front end 212 to the fourteenth front end 214 is referred to as the wiring width of the fourth metal layer 54. The wiring width of the fourth metal layer 54 is as follows... Figure 11 The diagram shows L1.
[0124] One example of a manufacturing method for a modified version of the first embodiment differs from the manufacturing method of the first embodiment in that, in Figure 7In the wiring formation of step S2 shown, the wiring pattern of the screen mask 21 is different, so repeated descriptions are omitted here.
[0125] The effect of the variation of the first embodiment is the same as that of the thermal printhead 10 of the first embodiment.
[0126] [Second Implementation]
[0127] The thermal printhead 10 of the second embodiment will be described using the accompanying drawings. Figure 12 yes Figure 1 A magnified view A3 of the periphery A of the heating resistor layer 6 shown. Figure 13 It will be along Figure 12 An enlarged diagram illustrating the schematic cross-sectional structure of line B3-B3. Figure 13 This is the YZ plane viewed from the X direction. Figure 14 It will be along Figure 12 An enlarged diagram illustrating the schematic cross-sectional structure of line C3-C3. Figure 14 This is the XZ plane viewed from the Y direction.
[0128] The thermal printhead 10 in the second embodiment is as follows: Figure 12 , Figure 13 As shown, unlike the first embodiment, it also has a second heat storage layer 9. The second heat storage layer 9 temporarily stores a portion of the heat generated by the heating resistor layer 6.
[0129] Second heat storage layer 9 Figure 12 , Figure 13 and Figure 14 As shown, the first heat storage layer 2 is disposed thereon, extends in the X direction, and is configured to cover at least a portion of the first metal layer 51. Additionally, the second heat storage layer 9 is configured to cover at least a portion of the second metal layer 52.
[0130] Second heat storage layer 9 Figure 12 and Figure 13 It is positioned in the Y direction between the first metal layer 51 and the second metal layer 52. Furthermore, the second heat storage layer 9 is positioned in contact with the heating resistor layer 6.
[0131] Heating resistive layer 6 Figure 13 , Figure 14 As shown, it is disposed on the second heat storage layer 9. The other structures are the same as in the first embodiment.
[0132] Next, an example of the manufacturing method of the thermal printhead 10 according to the second embodiment will be described.
[0133] Figure 15 This is a flowchart of the main processes in manufacturing the thermal printhead 10 according to the second embodiment. Figure 16A, Figure 16B yes Figure 15 The cross-sectional structure of the heating resistor layer 6 around A3 in each process shown is along line B3-B3. That is, Figure 16A , Figure 16B This is the YZ plane viewed from the X direction. In the following description, where the manufacturing method of the thermal printhead 10 of the first embodiment is repeated, the description is omitted.
[0134] (S11) First, in Figure 15 In step S11 shown, a first heat storage layer 2 is formed on the substrate 1. Here, step S11 of the manufacturing method of the thermal printhead 10 of the second embodiment is common to step S1 of the manufacturing method of the thermal printhead 10 of the first embodiment.
[0135] (S12) Next, in Figure 15 In step S12 shown, wiring 5 is formed on the first heat storage layer 2. Here, step S12 of the manufacturing method of the thermal printhead 10 of the second embodiment is common to step S2 of the manufacturing method of the thermal printhead 10 of the first embodiment.
[0136] (S13) in Figure 15 In step S13 shown, a second heat storage layer 9 is formed on the first heat storage layer 2. Here, the second heat storage layer 9 is formed, for example, using screen printing. Specifically, the second heat storage layer 9 is as follows: Figure 1 , Figure 12 and Figure 16A As shown, the process involves applying a glass paste, such as silica, onto the first heat storage layer 2, covering a portion of the wiring 5, using a screen printing method, and then firing the glass paste at, for example, a temperature of 1200°C. Furthermore, the temperature of 1200°C refers to a range of 1100 to 1300°C when using silica glass paste.
[0137] (S14-1) in Figure 15 In step S14, a heating resistor layer 6 is formed on the second heat storage layer 9. Here, the heating resistor layer 6 is formed, for example, using screen printing. Specifically, the heating resistor layer 6 is formed as follows: Figure 1 , Figure 12 and Figure 16B As shown, the paste of the heating resistor layer 6 is printed in a strip shape on the second heat storage layer 9, covering a portion of the wiring 5. Furthermore, the heating resistor layer 6 is as follows... Figure 12 , Figure 14 The diagram shows a plurality of heating elements 61, which can be formed for each of the wiring 5.
[0138] (S14-2) Next, the heating resistance layer 6 is formed by drying the paste printed on it and firing it at a temperature of 800°C to 850°C.
[0139] In the manufacturing process of the thermal printhead 10 of the second embodiment, the process after forming the heating resistor layer 6 is known, so the description of the process is omitted.
[0140] The thermal printhead 10 of the second embodiment is completed through the above procedures.
[0141] The thermal printhead 10 of the second embodiment has the same effect as the thermal printhead 10 of the first embodiment.
[0142] As explained above, according to this embodiment, the flow of the metal paste 22 can be suppressed, and a thermal printhead 10 and its manufacturing method can be provided that can form a finer wiring width.
[0143] [Other Implementation Methods]
[0144] As described above, several embodiments have been described, and the discussions and drawings that form part of this invention are illustrative and should not be construed as limiting. According to this invention, those skilled in the art will understand various alternative embodiments, examples, and application techniques. Thus, this embodiment includes various embodiments not described herein.
Claims
1. A thermal printhead, characterized by, include: substrate; A first heat storage layer disposed on the substrate; The wiring has a first metal layer disposed on the first heat storage layer and a second metal layer disposed on the first heat storage layer at a distance from the first metal layer. and A heating resistor layer is disposed on the first heat storage layer, electrically connected to the first metal layer and the second metal layer, and has a plurality of heating elements spaced apart from each other. The first heat storage layer is an insulating layer containing a low-temperature co-fired ceramic material comprising glass powder and ceramic powder, and is a raw sheet before firing, configured to absorb the solvent in the metal paste used to form the first metal layer and the second metal layer.
2. The thermal printhead as described in claim 1, characterized in that: The heating resistance layer covers at least a portion of the first metal layer.
3. The thermal printhead as described in claim 1, characterized in that: The heating resistance layer covers at least a portion of the second metal layer.
4. The thermal printhead as described in claim 1, characterized in that: When the main scanning direction is designated as the first direction, and the sub-scanning direction intersecting the main scanning direction is designated as the second direction... The heating resistor layer is arranged extending in the first direction and sandwiched between the first metal layer and the second metal layer in the second direction.
5. The thermal printhead as described in claim 4, characterized in that: When the direction of viewing the device surface on the substrate from above is defined as the third direction... The heating resistor layer has a plurality of heating elements arranged along the first direction in the third direction.
6. The thermal printhead as described in claim 5, characterized in that: The first metal layer is disposed extending in the first direction, and the cross-section of the third front end portion in the second direction is arc-shaped.
7. The thermal printhead as described in claim 6, characterized in that: In the second direction, the cross-sections of the second front end and the fourth front end of the first metal layer are arc-shaped.
8. The thermal printhead as described in claim 6, characterized in that: The second metal layer is arranged at intervals in the first direction, and the cross-section of the sixth front end in the second direction is arc-shaped.
9. The thermal printhead as described in claim 8, characterized in that: In the first direction, the cross-sections of the fifth front end and the seventh front end of the second metal layer are arc-shaped.
10. The thermal printhead as described in claim 1, characterized in that: It also has a second heat storage layer that temporarily stores a portion of the heat generated by the heating resistor layer. The second heat storage layer is disposed on the first heat storage layer and covers at least a portion of the first metal layer and the second metal layer, and is in contact with the heating resistance layer.
11. A method of manufacturing a thermal printhead, characterized by, have: The process of forming the first heat storage layer on the substrate; The process of forming wiring using metal paste on the first heat storage layer; and The process of forming a heating resistance layer on the first heat storage layer, which is electrically connected to the wiring and has a plurality of heating parts spaced apart from each other. The process of forming the first heat storage layer includes a process of forming an insulating layer, which has a low-temperature co-fired ceramic material comprising glass powder and ceramic powder, is composed of green sheets, and is configured to absorb solvents in the metal paste during the process of forming the wiring.
12. The method for manufacturing a thermal printhead as described in claim 11, characterized in that: The wiring process includes the steps of forming a first metal layer and a second metal layer.
13. The method for manufacturing a thermal printhead as described in claim 12, characterized in that: The process of forming the first metal layer and the second metal layer uses screen printing.
14. The method for manufacturing a thermal printhead as described in claim 12, characterized in that: The process of forming the heating resistance layer involves configuring the heating resistance layer to extend in a first direction and forming the heating resistance layer in a manner that it is sandwiched between the first metal layer and the second metal layer in a second direction.
15. The method for manufacturing a thermal printhead as described in claim 14, characterized in that: The process of forming the heating resistance layer involves forming a plurality of heating elements arranged along the first direction in the third direction.
16. The method for manufacturing a thermal printhead as described in claim 11, characterized in that: The process of forming the heating resistance layer uses screen printing.