Insulating substrate

Abstract

To provide an insulating substrate capable of suppressing swelling of a glaze layer on an outer peripheral edge portion of a main surface of a ceramic base material.SOLUTION: An insulating substrate (100) of the present disclosure includes: a ceramic base material (10) having a main surface (10a); a plurality of first ribs (20) formed on the main surface; and a glaze layer (30) arranged on the main surface so as to cover the plurality of first ribs. The plurality of first ribs extend along a first direction (DR1) in plan view and arrayed so as to be spaced in a second direction (DR2) orthogonal to the first direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to insulating substrates. [Background technology]

[0002] For example, JP 2022-78607 A (Patent Document 1) describes a thermal printhead. The thermal printhead described in Patent Document 1 is formed using an insulating substrate.

[0003] The insulating substrate has a ceramic base material and a glaze layer. The ceramic base material has a main surface. The glaze layer is disposed on the main surface. The glaze layer is formed by applying a glass paste onto the main surface and firing the applied paste. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2022-78607 A [Summary] When the glass paste is fired, the glass paste on the outer peripheral edge of the main surface is likely to dry. Therefore, the glass paste flows toward the outer peripheral edge of the main surface, and the glass paste rises on the outer peripheral edge of the main surface. As a result, the glaze layer formed by firing the glass paste also rises on the outer peripheral edge of the main surface (coffee ring phenomenon). Since it is difficult to use the portion of the insulating substrate including the raised glaze layer for forming a thermal print head, the number of thermal print heads that can be formed using one insulating substrate is reduced.

[0005] The insulating substrate of the present disclosure includes a ceramic substrate having a main surface, a plurality of first ribs formed on the main surface, and a glaze layer disposed on the main surface so as to cover the plurality of first ribs. The plurality of first ribs extend along a first direction in a plan view and are arranged at intervals in a second direction perpendicular to the first direction. [Brief description of the drawings]

[0006] [Figure 1] FIG. 2 is a plan view of an insulating substrate 100. [Diagram 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Diagram 3] FIG. 2 is a plan view of a thermal printhead 200. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Diagram 5] 4 is a cross-sectional view taken along line VV in FIG. [Figure 6] 1 is a manufacturing process diagram of an insulating substrate 100. FIG. [Figure 7] FIG. 11 is a cross-sectional view illustrating a rib forming step S2. [Figure 8] 3A to 3C are diagrams illustrating the manufacturing process of the thermal printhead 200. [Figure 9] 11 is a cross-sectional view illustrating a wiring layer forming step S5. FIG. [Figure 10] FIG. 11 is a cross-sectional view illustrating a heating element forming step S7. [Figure 11] FIG. 2 is a plan view of an insulating substrate 100A. [Figure 12] 12 is a cross-sectional view taken along line XII-XII in FIG. 11. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] [Detailed Description] The details of the embodiments of the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are designated by the same reference numerals, and redundant description will not be repeated.

[0008] (First embodiment) The insulating substrate according to the first embodiment will be described below. The insulating substrate according to the first embodiment is designated as insulating substrate 100.

[0009] <Configuration of insulating substrate 100> The configuration of the insulating substrate 100 will be described below.

[0010] Fig. 1 is a plan view of an insulating substrate 100. Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1. As shown in Figs. 1 and 2, the insulating substrate 100 has a ceramic base material 10, a plurality of ribs 20, and a glaze layer 30.

[0011] The ceramic substrate 10 has a principal surface 10a and a principal surface 10b. The principal surface 10a and the principal surface 10b are end surfaces in the thickness direction of the ceramic substrate 10. The principal surface 10b is the surface opposite to the principal surface 10a. The main component of the material constituting the ceramic substrate 10 is a ceramic such as alumina (Al2O3). The term "main component" means that the main component accounts for more than 50 percent of the components in the material.

[0012] The rib 20 is formed on the main surface 10a. The rib 20 extends along a first direction DR1 in a plan view. The plan view refers to a view from the main surface 10a side along the normal direction of the main surface 10a. The multiple ribs 20 are arranged in a second direction DR2 at intervals in a plan view. The second direction DR2 is a direction perpendicular to the first direction DR1. The interval between two adjacent ribs 20 is, for example, equal. The interval between two adjacent ribs 20 is, for example, 20 mm or less. The lower limit of the interval between two adjacent ribs 20 is not particularly limited as long as the two ribs 20 can be formed with an interval between them. The width of the rib 20 in the second direction DR2 is, for example, 500 μm or less. The lower limit of the width of the rib 20 in the second direction DR2 is not particularly limited as long as the rib 20 can be formed.

[0013] The height of the rib 20 is height H. The main component of the material constituting the rib 20 is, for example, ceramic. The rib 20 is formed, for example, of a sintered body containing a plurality of particles. The particles contained in the sintered body constituting the rib 20 are ceramic particles. The material constituting the ceramic particles contained in the sintered body may be the same as or different from the material constituting the ceramic substrate 10. The average particle size of the particles contained in the sintered body is, for example, 1 μm or less. The average particle size of the particles contained in the sintered body is measured, for example, by a laser diffraction / scattering method.

[0014] The glaze layer 30 is disposed on the main surface 10a so as to cover the multiple ribs 20. The main component of the constituent material of the glaze layer 30 is glass. The thickness of the glaze layer 30 is defined as thickness T. The thickness T is the distance between the main surface 10a and the surface of the glaze layer 30. The height H is preferably 0.7 times or more and less than 1.0 times the thickness T. The thickness T is preferably 100 μm or more, 150 μm or more, or 200 μm or more. The thickness T is, for example, 300 μm or less.

[0015] <Configuration of thermal print head 200> The configuration of the thermal printhead 200 will now be described.

[0016] A thermal printhead formed using the insulating substrate 100 is referred to as a thermal printhead 200. FIG. 3 is a plan view of the thermal printhead 200. Note that the protective layer 60 is omitted in FIG. 3. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3. FIG. 5 is a cross-sectional view taken along line VV in FIG. 3. As shown in FIGS. 3 to 5, the thermal printhead 200 has an insulating substrate 100, a wiring layer 40, a heating element 50, and a protective layer 60.

[0017] The wiring layer 40 is disposed on the glaze layer 30. The wiring layer 40 has a common electrode 41 and a plurality of individual electrodes 42. The main component of the constituent material of the wiring layer 40 is, for example, gold (Au).

[0018] The common electrode 41 has a strip portion 41a and a plurality of protrusions 41b. The strip portion 41a extends along the first direction DR1 in a plan view. The plurality of protrusions 41b are arranged in the first direction DR1 at intervals. The protrusions 41b protrude from the strip portion 41a along the second direction DR2. The individual electrode 42 has a tip portion 42a at one end. The tip portion 42a extends along the second direction DR2 in a plan view. The protrusions 41b and the tip portions 42a are arranged alternately in the first direction DR1. The individual electrode 42 has a bonding pad 42b at the other end.

[0019] Although not shown, the thermal printhead 200 further has a first wiring and a second wiring. The first wiring is mainly disposed on the glaze layer 30 and is electrically connected to the common electrode 41. The second wiring is disposed on the first wiring. The first wiring and the second wiring are formed of, for example, a sintered body containing silver (Ag) particles.

[0020] The heating element 50 extends along the first direction DR1 in plan view. The heating element 50 is disposed on the glaze layer 30 while overlapping with the protrusion 41b and the tip 42a. The heating element 50 is made of, for example, glass and conductive particles contained in the glass. The conductive particles are made of, for example, ruthenium oxide (RuO2). The adjacent protrusions 41b and tips 42a are electrically connected to each other by the heating element 50.

[0021] The protective layer 60 is disposed on the glaze layer 30 so as to cover the wiring layer 40, the first wiring, the second wiring, and the heating element 50. An opening 61 is formed in the protective layer 60. The bonding pad 42b is exposed from the opening 61. The main component of the material constituting the protective layer 60 is, for example, glass.

[0022] A fixed potential is applied to the common electrode 41. A potential is selectively applied to each of the individual electrodes 42 from a driver IC. Therefore, the heating element 50 connecting the tip 42a of one individual electrode 42 to which the potential is selectively applied and the protrusion 41b adjacent to the tip 42a of the individual electrode 42 is energized and generates heat. This heat is transferred to the paper, thereby printing on the paper.

[0023] <Method of manufacturing the insulating substrate 100> A method for manufacturing the insulating substrate 100 will now be described.

[0024] Fig. 6 is a manufacturing process diagram of the insulating substrate 100. As shown in Fig. 6, the manufacturing method of the insulating substrate 100 includes a preparation step S1, a rib forming step S2, and a glaze layer forming step S3. The rib forming step S2 is performed after the preparation step S1. The glaze layer forming step S3 is performed after the rib forming step S2.

[0025] In the preparation step S1, the ceramic substrate 10 is prepared. FIG. 7 is a cross-sectional view illustrating the rib forming step S2. As shown in FIG. 7, in the rib forming step S2, the rib 20 is formed. In the rib forming step S2, first, a paste containing particles constituting the rib 20 is applied onto the main surface 10a, and the paste is dried. This application and drying step is preferably repeated multiple times. Second, the paste disposed on the main surface 10a is fired. Thus, the rib 20 is formed. The height H increases by repeating the above application and drying steps multiple times. The above application may be performed by printing or using a dispenser.

[0026] In the glaze layer forming step S3, the glaze layer 30 is formed. The glaze layer 30 is formed by applying a paste containing glass onto the main surface 10a so as to cover the ribs 20 and firing the applied paste. In this manner, the insulating substrate 100 having the structure shown in Figs. 1 and 2 is formed.

[0027] <Method of Manufacturing Thermal Printhead 200> A method for manufacturing the thermal printhead 200 will now be described.

[0028] FIG. 8 is a manufacturing process diagram of the thermal printhead 200. As shown in FIG. 8, the manufacturing method of the thermal printhead 200 includes a preparation step S4, a wiring layer forming step S5, a first wiring forming step S6, a heating element forming step S7, a second wiring forming step S8, a protective layer forming step S9, and a singulation step S10. The wiring layer forming step S5 is performed after the preparation step S4. The first wiring forming step S6 is performed after the wiring layer forming step S5. The heating element forming step S7 is performed after the first wiring forming step S6. The second wiring forming step S8 is performed after the heating element forming step S7. The protective layer forming step S9 is performed after the second wiring forming step S8. The singulation step S10 is performed after the protective layer forming step S9.

[0029] In the preparation step S4, an insulating substrate 100 is prepared. FIG. 9 is a cross-sectional view for explaining the wiring layer formation step S5. As shown in FIG. 9, in the wiring layer formation step S5, a wiring layer 40 is formed. In the wiring layer formation step S5, first, a resinate paste containing a constituent material of the wiring layer 40 is applied onto the glaze layer 30. Second, a metal layer is formed by baking the applied resinate paste. Third, a resist pattern is formed on the metal layer. The resist pattern is formed by applying a photoresist onto the metal layer, and exposing and developing the applied photoresist. Fourth, the metal layer is etched using the resist pattern as a mask. As a result, the metal layer is patterned to become the wiring layer 40.

[0030] In the first wiring forming step S6, the first wiring is formed. The first wiring is formed by applying a conductive paste containing a plurality of silver particles and firing the applied conductive paste. FIG. 10 is a cross-sectional view explaining the heating element forming step S7. As shown in FIG. 10, in the heating element forming step S7, the heating element 50 is formed. In the heating element forming step S7, first, a conductive paste containing glass and ruthenium oxide particles is applied. Second, the applied conductive paste is fired to form the heating element 50.

[0031] In the second wiring forming step S8, the second wiring is formed. The second wiring is formed by applying a conductive paste containing a plurality of silver particles and firing the applied conductive paste. In the protective layer forming step S9, the protective layer 60 is formed. The protective layer 60 is formed by applying a paste containing glass and firing the applied paste. In the singulation step S10, the insulating substrate 100 is cut along the boundaries of the thermal printheads 200, for example, by irradiation with laser light. As a result of the above, a plurality of thermal printheads 200 having the structures shown in Figs. 3 to 5 are obtained.

[0032] <Effects of the insulating substrate 100> The effects of the insulating substrate 100 will be described below.

[0033] The glaze layer 30 is formed by applying a paste containing glass onto the main surface 10a and firing the applied glass. The applied paste is easily dried on the outer peripheral edge of the main surface 10a, and the paste around the outer peripheral edge flows toward the outer peripheral edge. As a result, the glaze layer 30 rises on the outer peripheral edge of the main surface 10a, resulting in a coffee ring phenomenon. The rise of the glaze layer 30 becomes more noticeable as the thickness T increases. For example, when forming a glaze layer 30 with a thickness T of 200 μm, if there is no rib 20, the rise height of the glaze layer 30 on the outer peripheral edge of the main surface 10a may exceed 50 μm. It is difficult to form a thermal print head 200 on the part where the glaze layer 30 has risen, and the number of thermal print heads 200 obtained from one insulating substrate 100 decreases.

[0034] In this regard, since the insulating substrate 100 has the ribs 20 formed on the main surface 10a, the paste applied to the main surface 10a is partitioned by the ribs 20, and the volume of the paste that contributes to the coffee ring phenomenon is reduced. As a result, the insulating substrate 100 can suppress the glaze layer 30 from swelling on the outer main edge of the main surface 10a, and furthermore, the number of thermal printheads 200 that can be obtained from one insulating substrate 100 can be increased.

[0035] If the height H is too small compared to the thickness T, the applied paste may flow beyond the rib 20. Therefore, by setting the height H to be 0.7 times or more and less than 1.0 times the thickness T, it is possible to more reliably suppress the rise of the glaze layer 30. If the rib 20 is made of a sintered body containing a plurality of particles, it is possible to easily adjust the height H by repeatedly applying and drying a paste containing such particles. Furthermore, if the average particle size of such particles is 1.0 μm or less, it is possible to form the rib 20 with good shape precision.

[0036] Second embodiment An insulating substrate according to the second embodiment will be described. The insulating substrate according to the second embodiment is designated as insulating substrate 100A. Here, differences from insulating substrate 100A will be mainly described, and overlapping descriptions will not be repeated.

[0037] <Configuration of insulating substrate 100A> The configuration of the insulating substrate 100A will be described below.

[0038] Fig. 11 is a plan view of the insulating substrate 100A. Fig. 12 is a cross-sectional view taken along line XII-XII in Fig. 11. As shown in Figs. 11 and 12, the insulating substrate 100A has a ceramic base 10, a rib 20, and a glaze layer 30. In this regard, the configuration of the insulating substrate 100A is common to the configuration of the insulating substrate 100.

[0039] The insulating substrate 100A further has a plurality of ribs 21. In this respect, the configuration of the insulating substrate 100A is common to that of the insulating substrate 100. The ribs 21 extend along the second direction DR2 in a plan view. That is, the ribs 21 intersect with the ribs 20 in a plan view. The plurality of ribs 21 are arranged in the first direction DR1 at intervals in a plan view. The configuration of the ribs 21 is the same as that of the ribs 20 except for the extending direction and the arranging direction in a plan view. The interval between two adjacent ribs 21 is, for example, 20 mm or less. The lower limit of the interval between two adjacent ribs 21 is not particularly limited as long as the two ribs 21 can be formed with an interval between them. The width of the rib 21 in the first direction DR1 is, for example, 500 μm or less. The lower limit of the width of the rib 21 in the first direction DR1 is not particularly limited as long as the rib 21 can be formed.

[0040] <Method of manufacturing insulating substrate 100A> A method for manufacturing the insulating substrate 100A will be described below.

[0041] The manufacturing method of the insulating substrate 100A is common to the manufacturing method of the insulating substrate 100 in that it includes a preparation step S1, a rib forming step S2, and a glaze layer forming step S3. The manufacturing method of the insulating substrate 100A differs from the manufacturing method of the insulating substrate 100 in that the rib 21 is also formed in the same manner as the rib 20 in the rib forming step S2.

[0042] <Effects of insulating substrate 100A> The effects of the insulating substrate 100A will be described below.

[0043] In the insulating substrate 100A, ribs 21 are formed on the main surface 10a in addition to the ribs 20. Therefore, in the insulating substrate 100A, not only the flow of the paste along the second direction DR2 but also the flow of the paste along the first direction DR1 is suppressed, so that it is possible to further suppress the rise of the glaze layer 30 on the outer peripheral edge portion of the main surface 10a.

[0044] (Additional Note) The embodiments of the present disclosure include the following features.

[0045] <Appendix 1> a ceramic substrate having a major surface; A plurality of first ribs formed on the main surface; a glaze layer disposed on the main surface so as to cover the first ribs; The insulating substrate, wherein the first ribs extend along a first direction in a plan view and are arranged at intervals in a second direction perpendicular to the first direction.

[0046] <Appendix 2> 2. The insulating substrate of claim 1, wherein the thickness of the glaze layer is greater than or equal to 0.7 times and less than 1.0 times the height of each of the first ribs.

[0047] <Appendix 3> 3. The insulating substrate according to claim 1, wherein the glaze layer has a thickness of 100 μm or more.

[0048] <Appendix 4> Further comprising a plurality of second ribs formed on the main surface, The first ribs extend along the second direction in a plan view and are arranged at intervals in the first direction. 4. The insulating substrate of claim 1, wherein the glaze layer further covers the second ribs.

[0049] <Appendix 5> 5. The insulating substrate according to claim 1, wherein the material constituting each of the first ribs is a sintered body containing a plurality of particles.

[0050] <Appendix 6> 6. The insulating substrate according to claim 5, wherein the average particle size of the plurality of particles is 1.0 μm or less.

[0051] Although the embodiment of the present disclosure has been described above, the above-mentioned embodiment can be modified in various ways. The scope of the present invention is not limited to the above-mentioned embodiment. The scope of the present invention is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims. [Explanation of symbols]

[0052] 100,100A insulating substrate, 10 ceramic base material, 10a,10b main surface, 20,21 rib, 30 glaze layer, 40 wiring layer, 41 common electrode, 41a strip portion, 41b protrusion portion, 42 individual electrode, 42a tip portion, 42b bonding pad, 50 heating element, 60 protective layer, 61 opening, 200 thermal print head, DR1 first direction, DR2 second direction, H height, S1 preparation step, S2 rib forming step, S3 glaze layer forming step, S4 preparation step, S5 wiring layer forming step, S6 first wiring forming step, S7 heating element forming step, S8 second wiring forming step, S9 protective layer forming step, S10 singulation step, T thickness.

Claims

1. a ceramic substrate having a major surface; A plurality of first ribs formed on the main surface; a glaze layer disposed on the main surface so as to cover the first ribs; The insulating substrate, wherein the first ribs extend along a first direction in a plan view and are arranged at intervals in a second direction perpendicular to the first direction.

2. The insulating substrate according to claim 1 , wherein the thickness of the glaze layer is equal to or greater than 0.7 times and less than 1.0 times the height of each of the first ribs.

3. The insulating substrate according to claim 1 , wherein the glaze layer has a thickness of 100 μm or more.

4. Further comprising a plurality of second ribs formed on the main surface, The first ribs extend along the second direction in a plan view and are arranged at intervals in the first direction. The insulating substrate of claim 1 , wherein the glaze layer further covers the second plurality of ribs.

5. The insulating substrate according to claim 1 , wherein the material constituting each of the plurality of first ribs is a sintered body containing a plurality of particles.

6. The insulating substrate according to claim 5 , wherein the average particle size of the plurality of particles is 1.0 μm or less.

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