Thermal printing head

Abstract

A thermal print head includes a substrate, an enamel layer, and a planarization layer. The substrate has a first surface. The glaze layer is arranged on the first surface. The planarization layer is arranged on the first surface. The planarization layer includes a crystalline portion.

Description

Technical Field

[0001] This invention relates to a thermal printhead. Background Technology

[0002] Japanese Patent Application Publication No. 2022-52544 discloses a thermal printhead comprising a substrate, a glaze layer, a wiring layer, and a heating resistor. The glaze layer includes a glass layer forming a smooth surface on which the wiring layer is configured. Summary of the Invention

[0003] The purpose of this invention is to provide a thermal printhead that can suppress wire breakage in the wiring layer.

[0004] The thermal printhead of the present invention includes a substrate, an enamel layer, and a planarization layer. The substrate has a first surface. The enamel layer is disposed on the first surface. The planarization layer is disposed on the first surface. The planarization layer includes crystalline portions.

[0005] The above and other objects, features, aspects and advantages of the present invention will become clear from the following detailed description of the invention as understood in conjunction with the accompanying drawings. Attached Figure Description

[0006] Figure 1 This is a schematic top view of the thermal printhead in Embodiment 1.

[0007] Figure 2 yes Figure 1 A rough enlarged sectional view of line segment II-II.

[0008] Figure 3 yes Figure 1 A rough, enlarged top view of a section in Region III.

[0009] Figure 4 This is an SEM image showing a cross-section of the planarization layer of the thermal printhead in Embodiment 1.

[0010] Figure 5 This is a flowchart of the manufacturing method of the thermal printhead in Embodiment 1.

[0011] Figure 6 This is a schematic enlarged cross-sectional view showing a step in the manufacturing method of the thermal printhead of Embodiment 1.

[0012] Figure 7 This is a schematic enlarged cross-sectional view showing a step in the manufacturing method of the thermal printhead of Embodiment 1.

[0013] Figure 8 This is a schematic enlarged cross-sectional view showing a step in the manufacturing method of the thermal printhead of Embodiment 1.

[0014] Figure 9 is a schematic partial enlarged sectional view showing one step in the manufacturing method of the thermal printhead of Embodiment 1.

[0015] Figure 10 is a schematic partial enlarged sectional view showing one step in the manufacturing method of the thermal printhead of Embodiment 1.

[0016] Figure 11 is a schematic partial enlarged sectional view showing one step in the manufacturing method of the thermal printhead of Embodiment 1.

[0017] Figure 12 is a schematic partial enlarged sectional view showing one step in the manufacturing method of the thermal printhead of Embodiment 1.

[0018] Figure 13 is a schematic partial enlarged sectional view showing one step in the manufacturing method of the thermal printhead of Embodiment 1. DETAILED DESCRIPTION

[0019] The detailed description of the embodiments of the present disclosure is given based on the drawings. Furthermore, in the following drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof is not repeated. The structure of at least a part of the embodiments described below can be arbitrarily combined.

[0020] (Embodiment 1)

[0021] <Structure of Thermal Printhead>

[0022] Figure 1 is a schematic plan view of the thermal printhead 1 of Embodiment 1. Figure 2 is a schematic partial enlarged sectional view at a line segment II-II of Figure 1 Figure 3 is a schematic partial enlarged plan view in a region III of Figure 1 As shown in Figure 1 and Figure 2 , the thermal printhead 1 of this Embodiment 1 is provided with a substrate 10, a glaze layer 11, a planarization layer 15, wiring layers 20, 45, a heat generating resistor 30, a protective layer 33, a conductive wire 41, a sealing member 43, and a plurality of external connection terminals 50. In Figure 1 and Figure 3 , the illustration of the protective layer 33 is omitted.

[0023] The substrate 10 is a ceramic substrate such as an alumina substrate. As shown in Figure 2 ​As shown, the substrate 10 has a first surface 10a. In a top view of the first surface 10a (hereinafter simply referred to as "top view"), the long side direction of the substrate 10 is defined as the x-direction. The x-direction is the main scanning direction. The short side direction of the substrate 10 is defined as the y-direction. The y-direction is the sub-scanning direction. The thickness direction of the substrate 10 is defined as the z-direction. The z-direction is perpendicular to both the x-direction (main scanning direction) and the y-direction (sub-scanning direction). In the top view, the y-direction (sub-scanning direction) is the transport direction of the printing medium (e.g., thermal recording paper).

[0024] like Figure 2 As shown, a glaze layer 11 is disposed on the first surface 10a of the substrate 10. The glaze layer 11 includes, for example, an amorphous portion formed of amorphous glass. The thermal conductivity of the glaze layer 11 may also be lower than that of the substrate 10.

[0025] like Figure 2 As shown, the glaze layer 11 is disposed on a portion of the first surface 10a. That is, the glaze layer 11 is a so-called partial glaze layer. The glaze layer 11 includes a heated glaze 12 and an applied glaze 13.

[0026] The heating glaze 12 extends along the x-direction when viewed from above the first surface 10a. The heating glaze 12 is disposed below the heating resistor 30. The heating glaze 12 suppresses heat loss from the heating resistor 30 to the substrate 10. The heating glaze 12 is a heat storage layer. The heating glaze 12 protrudes from a portion of the first surface 10a. The heating glaze 12 increases the height of the heating resistor 30 above the first surface 10a. The heating resistor 30 is pressed against a printing medium (e.g., thermal recording paper).

[0027] The patch glaze 13 and the heating glaze 12 are configured separately in the y-direction. In a top view of the first surface 10a, the patch glaze 13 extends in the x-direction. The patch glaze 13 supports a portion of the wiring layer 20 and the drive circuitry 40.

[0028] like Figure 2 As shown, a planarization layer 15 is disposed on the first surface 10a. The material constituting the planarization layer 15 includes glass. The material constituting the planarization layer 15 may also include alumina. Specifically, the planarization layer 15 includes, for example, an amorphous portion 15a formed of amorphous glass and a crystalline portion 15b formed of crystallized glass (see reference). Figure 4 The planarization layer 15 may also include a filler 15c formed of alumina.

[0029] The planarization layer 15 includes a first planarization layer 16 and a second planarization layer 17. The first planarization layer 16, viewed from the first surface 10a, is disposed between the heated glaze 12 and the applied glaze 13. The second planarization layer 17 is disposed separately from the first planarization layer 16 in the y-direction. The second planarization layer 17 is disposed on the opposite side of the first planarization layer 16 in the y-direction relative to the heated glaze 12.

[0030] like Figure 2 As shown, the thickness of the planarization layer 15 in the z-direction is less than the thickness of the glaze layer 11 in the z-direction. Specifically, the thickness of the planarization layer 15 in the z-direction is less than the thickness of the heated glaze 12 in the z-direction. The thickness of the planarization layer 15 in the z-direction is smaller than the thickness of the patch glaze 13 in the z-direction. The surface roughness of the planarization layer 15 is less than the surface roughness of the first surface 10a. Therefore, by distributing the wiring layer 20 on the planarization layer 15, it is possible to suppress the breakage of the wiring layer 20 caused by the surface roughness of the first surface 10a.

[0031] like Figure 2 As shown, wiring layer 20 is disposed on glaze layer 11 and planarization layer 15. Wiring layer 20 forms a conductive path for energizing heating resistor 30. Wiring layer 20 includes common wiring 21 and multiple individual wirings 25.

[0032] like Figures 1 to 3 As shown, the common wiring 21 is disposed on the heating glaze 12, the patch glaze 13, the first planarization layer 16, and the second planarization layer 17. The common wiring 21 includes multiple strip portions 22, connecting portions 23, and detour portions 24.

[0033] like Figure 2 as well as Figure 3 As shown, a plurality of strip-shaped portions 22 are disposed on the heated glaze 12 and the second planarization layer 17. The plurality of strip-shaped portions 22 extend along the -y direction. The plurality of strip-shaped portions 22 are arranged at equal intervals in the x direction. The plurality of strip-shaped portions 22 are, for example, gold (Au) wiring. The plurality of strip-shaped portions 22 are formed from, for example, a sintered body of gold particles.

[0034] like Figure 2 as well as Figure 3 As shown, the connecting portion 23 is disposed on the second planarization layer 17. The connecting portion 23 extends along the x-direction. The connecting portion 23 is connected to a plurality of strip portions 22. The plurality of strip portions 22 are connected through the connecting portion 23. The connecting portion 23 is, for example, silver (Ag) wiring. The connecting portion 23 is formed of, for example, a silver particle sintered body.

[0035] like Figure 1 As shown, the detour portion 24 is connected to the connecting portion 23. The detour portion 24 extends from both ends of the connecting portion 23 in the x-direction along the -y-direction, bypassing multiple independent wirings 25. The detour portion 24 is disposed on the second planarization layer 17, the heating glaze 12, the first planarization layer 16, and the patch glaze 13. The detour portion 24 is, for example, silver (Ag) wiring. The detour portion 24 is formed from, for example, a sintered body of silver particles. The materials constituting the connecting portion 23 and the detour portion 24 include silver (Ag) instead of gold (Au), thus reducing the manufacturing cost of the thermal printhead 1.

[0036] Multiple independent wirings 25 partially energize the heating resistor 30. These independent wirings 25 are disposed on the heating glaze 12, the surface mount glaze 13, and the first planarization layer 16. For example... Figure 2 As shown, the multiple independent wirings 25 each include a first independent wiring portion 26 and a second independent wiring portion 27.

[0037] The first independent wiring portion 26 is disposed on the heated glaze 12 and the first planarization layer 16. The first independent wiring portion 26 is, for example, gold (Au) wiring. The first independent wiring portion 26 is formed from, for example, a sintered body of gold particles.

[0038] The second independent wiring portion 27 is connected to the first independent wiring portion 26. The second independent wiring portion 27 is disposed on the patch glaze 13 and the first planarization layer 16. The second independent wiring portion 27 is, for example, silver (Ag) wiring. The second independent wiring portion 27 is formed, for example, a sintered body of silver particles. The material constituting the second independent wiring portion 27 includes silver (Ag) instead of gold (Au), thus reducing the manufacturing cost of the thermal printhead 1. The second independent wiring portion 27 can also be a laminate of a first layer 28 and a second layer 29. The first layer 28 is formed, for example, a sintered body of silver particles. The second layer 29 is formed, for example, a glass frit including silver particles.

[0039] like Figure 1 As shown, when viewed from above, the multiple independent wirings 25 include independent wiring areas 25a, 25b, and 25c, respectively.

[0040] like Figure 2 As shown, the independent routing area 25a is the portion of the independent routing 25 configured on the first planarization layer 16. As... Figure 3 As shown, the independent wiring region 25a extends in a direction inclined relative to the y-direction. (As...) Figure 2 As shown, the independent wiring region 25a is formed by a second independent wiring portion 27. The second independent wiring portion 27 can be configured in the independent wiring region 25a. That is, a first independent wiring portion 26 can also be configured in the independent wiring region 25a. From a different viewpoint, the first independent wiring portion 26 and the second independent wiring portion 27 can also be connected in the independent wiring region 25a. The independent wiring region 25a is longer than the independent wiring region 25b and longer than the independent wiring region 25c. Alternatively, the independent wiring region 25a can be shorter than both the independent wiring regions 25b and 25c.

[0041] like Figure 2 As shown, independent wiring region 25b is connected to one end of independent wiring region 25a. Independent wiring region 25b is the portion of independent wiring 25 disposed on the heating glaze 12 and is electrically connected to the heating resistor 30. Figure 3As shown, the independent wiring area 25b extends along the y-direction. (As...) Figure 2 As shown, the independent wiring area 25b is formed by the first independent wiring portion 26. A second independent wiring portion 27 may also be configured in the independent wiring area 25b. From another viewpoint, the first independent wiring portion 26 and the second independent wiring portion 27 may also be connected in the independent wiring area 25b.

[0042] like Figure 2 As shown, the independent wiring region 25c is connected to the other end of the independent wiring region 25a. Independent wiring region 25c is the portion of independent wiring 25 disposed on the surface mount 13 and is electrically connected to the drive circuit 40. Independent wiring region 25c extends along the y-direction (not shown). Figure 2 As shown, the independent wiring area 25c is formed by the second independent wiring portion 27.

[0043] like Figures 1 to 3 As shown, the heating resistor 30 is disposed on the top of the heating glaze 12. The heating resistor 30 extends along the x-direction. When viewed from above on the first surface 10a, the shape of the heating resistor 30 may also be, for example, strip-shaped. The heating resistor 30 protrudes relative to the heating glaze 12 toward the opposite side of the substrate 10 in the z-direction.

[0044] The heating resistor 30 is connected to the wiring layer 20. Specifically, as follows: Figure 3 As shown, the heating resistor 30 is connected to a plurality of strips 22 of the common wiring 21 and individual wiring regions 25b of a plurality of individual wirings 25. In top view, the heating resistor 30 is arranged to intersect with the plurality of strips 22 and the plurality of individual wiring regions 25b. The heating resistor 30 is formed to span the plurality of strips 22 and the individual wiring regions 25b. Printing is performed on a printing medium (e.g., thermal recording paper) by the heating of the heating resistor 30.

[0045] like Figure 2 As shown, the protective layer 33 protects the heating resistor 30. The protective layer 33 can also protect the common wiring 21 and multiple independent wirings 25. The protective layer 33 can also be a stack of the first protective layer 34 and the second protective layer 35.

[0046] A first protective layer 34 is formed on and covers the heating resistor 30. The first protective layer 34 may also be formed on the common wiring 21 and the plurality of independent wirings 25, covering the common wiring 21 and the plurality of independent wirings 25. The first protective layer 34 may also be formed on a portion of the glaze layer 11 and a portion of the planarization layer 15. The first protective layer 34 is an insulating layer. The first protective layer 34 is formed of, for example, amorphous glass. A second protective layer 35 is formed on the first protective layer 34. The second protective layer 35 is formed of, for example, amorphous glass.

[0047] like Figure 1 as well as Figure 2 As shown, the driving circuit 40 selectively energizes a plurality of independent wirings 25. The driving circuit 40 is, for example, a driving IC. In this embodiment 1, the plurality of driving circuits 40 are arranged separately from each other in the x-direction. The driving circuit 40 is disposed on the surface mount 13. The driving circuit 40 is electrically connected to the independent wiring regions 25c of the plurality of independent wirings 25 and the wiring layer 45. For example, the driving circuit 40 is electrically connected to the plurality of independent wiring regions 25b via conductive lines 41. The driving circuit 40 is electrically connected to the wiring layer 45 via conductive lines (not shown).

[0048] like Figure 2 As shown, the sealing member 43 seals the drive circuit 40. The sealing member 43 is electrically insulating. The sealing member 43 is formed of an insulating resin material, such as epoxy resin.

[0049] like Figure 1 As shown, wiring layer 45 electrically connects the drive circuit 40 and a plurality of external connection terminals 50. Wiring layer 45 is, for example, silver (Ag) wiring. Wiring layer 45 is formed in the same manner as, for example, the second independent wiring portion 27.

[0050] The plurality of external connection terminals 50 may be terminals for connecting cables using conductive bonding components such as solder, or terminals for mounting connectors. When viewed from above on the first surface 10a, the plurality of external connection terminals 50 are arranged along the outer periphery in the y-direction of the substrate 10. The plurality of external connection terminals 50 are electrically connected to the wiring layer 45 and the detour portion 24 of the common wiring 21. The plurality of external connection terminals 50 are formed, for example, in the same manner as the second independent wiring portion 27.

[0051] Here, the thermal printhead 1 of this embodiment 1 is characterized in that, as Figure 4 As shown, the planarization layer 15 includes a crystalline portion 15b formed from crystallized glass. Figure 4 This is a SEM (Scanning Electron Microscope) image showing a cross-section of the planarization layer 15 of the thermal printhead 1 in Embodiment 1.

[0052] As described above, in order to reduce the manufacturing cost of the thermal printhead 1, a silver layer is formed on the planarization layer 15 as silver wiring. When the planarization layer 15 includes an amorphous portion 15a instead of a crystalline portion 15b, bubbles may form on the planarization layer 15 when the silver layer is formed thereon. Furthermore, the planarization layer 15 may soften and flow during the formation of the silver layer. Therefore, due to bubbles formed in the planarization layer 15 or softening and flowing, the wiring layer 20 provided on the planarization layer 15 may break.

[0053] In particular, the softening point of the planarization layer 15 is lower than that of the glaze layer 11. Specifically, the softening point of the glaze layer 11 is above 900°C, while the softening point of the planarization layer 15 is below 800°C.

[0054] On the other hand, according to the thermal printhead 1 of this embodiment 1, such as Figure 4 As shown, the planarization layer 15 includes a crystalline portion 15b. Therefore, compared to a planarization layer that does not include the crystalline portion 15b, this planarization layer 15 has a higher softening point. Specifically, the softening point of the planarization layer 15 in this embodiment 1 is 800°C or higher and 870°C or lower. In this way, when the wiring layer 20 is formed, the generation of bubbles formed in the planarization layer 15 and the softening flow can be suppressed. As a result, wire breakage in the wiring layer 20 can be suppressed.

[0055] like Figure 4 As shown, the amorphous portion 15a occupies most of the planarization layer 15. From a different perspective, the crystalline portions 15b are arranged in a manner that is biased towards the amorphous portion 15a. That is, in the cross-section of the planarization layer 15, a plurality of crystalline portions 15b are dispersedly arranged in the amorphous portion 15a, which serves as the substrate. Specifically, in the cross-section of the planarization layer 15, the crystalline portions 15b occupy more than 10% of the area of ​​the planarization layer 15. In this way, the softening point of the planarization layer 15 increases, which can suppress the breakage of the wiring layer 20. In the cross-section of the planarization layer 15, the crystalline portions 15b can occupy more than 15% of the area of ​​the planarization layer 15.

[0056] exist Figure 4 In the diagram, the portion represented by the hollow rectangular area is the crystalline portion 15b. For example... Figure 4 As shown, in the cross-section of the planarization layer 15, the shape of the crystalline portion 15b can be a line extending in one direction, a rectangle, a circle, or an ellipse. Fillers such as alumina 15c can also be disposed in the amorphous portion 15a.

[0057] Furthermore, for example, if the amount of crystalline portion 15b in the planarization layer 15 increases due to the crystallization process, the softening point in the planarization layer 15 becomes higher, but the surface roughness of the planarization layer 15 increases. Therefore, the wiring layer 20 formed on the planarization layer 15 may break. Thus, in the cross-section of the planarization layer 15, the crystalline portion 15b may occupy less than 30% of the area of ​​the planarization layer 15. In the cross-section of the planarization layer 15, the crystalline portion 15b may occupy less than 25% of the area of ​​the planarization layer 15.

[0058] The crystalline portion 15b can be confirmed by observing the cross-section of the planarization layer 15. Specifically, the thermal printhead 1 is first machined using CP (Cross Section Polisher). Using a scanning electron microscope (SEM) manufactured by Hitachi High Technology Co., Ltd. (model: SU-70), the cross-section can be obtained as shown below. Figure 4 The cross-sectional image shown. The crystalline portion 15b can be identified from this cross-sectional image.

[0059] <Manufacturing Method of Thermal Printhead>

[0060] The manufacturing method of the thermal printhead 1 of Embodiment 1 will be described below. Figure 5 This is a flowchart of the manufacturing method of the thermal printhead 1 in Embodiment 1. Figures 6 to 13 This is a schematic enlarged cross-sectional view showing a step in the manufacturing method of the thermal printhead of Embodiment 1.

[0061] First, a process (S1) for preparing the substrate 10 is performed. In this process (S1), as follows: Figure 6 As shown, a substrate 10 having a first surface 10a is prepared. The substrate 10 is, for example, a ceramic substrate such as an alumina substrate.

[0062] Next, the process of forming the glaze layer 11 is performed (S2). In this process (S2), as follows: Figure 7 As shown, a glaze layer 11 is formed on the first surface 10a of the substrate 10. Specifically, a glass paste that will become the glaze layer 11 is printed on the first surface 10a of the substrate 10. The glass paste is then fired. In this way, the glaze layer 11 is formed. The glaze layer 11 includes, for example, a heated glaze 12 and a patch glaze 13.

[0063] Next, the process of forming the planarization layer 15 is performed (S3). In this process (S3), as... Figure 8 As shown, a planarization layer 15 is formed on the area exposed from the glaze layer 11 in the first surface 10a. For example, a glass paste that will become the planarization layer 15 is printed on the area exposed from the glaze layer 11 in the first surface 10a. The glass paste is then fired. In this way, the planarization layer 15 is formed. The planarization layer 15 includes, for example, a first planarization layer 16 and a second planarization layer 17.

[0064] By calcining the glass slurry at 800°C, crystallized glass can be precipitated in the planarization layer 15. As a result, a planarization layer 15 comprising crystalline portions 15b can be formed. The glass slurry forming the planarization layer 15 includes a nucleating material. Examples of nucleating materials include zirconium oxide (ZrO2), titanium oxide (TiO2), and phosphorus oxide (P2O5). By including a nucleating material in the glass slurry, crystallized glass precipitates in the planarization layer 15. The planarization layer 15 may include any one of alumina (Al2O3), lithium oxide (Li2O), zinc oxide (ZnO), and magnesium oxide (MgO).

[0065] Next, the process of forming wiring layer 20 (S4) is performed. In this process (S4), as... Figure 9 As shown, a wiring layer 20 is formed on the glaze layer 11 and the planarization layer 15. First, for example, a paste containing a conductive material such as gold (Au) particles is printed onto the heated glaze 12 and the planarization layer 15. A first conductive layer is formed by calcining the paste. The first conductive layer is patterned by a photolithography process. The photolithography process includes: a process of forming an etching mask by an exposure process and a development process; and a process of etching the first conductive layer using the etching mask. In this way, a strip 22 of common wiring 21 and an independent wiring region 25b (first independent wiring portion 26) of a plurality of independent wirings 25 are formed.

[0066] Next, a resin ester paste containing conductive materials such as silver (Ag) particles is printed onto the planarization layer 15, the heating glaze 12, and the mounting glaze 13. A glass paste containing conductive materials such as silver (Ag) particles and glass frit is printed onto a portion of the resin ester paste. A second conductive layer is formed by calcining the resin ester paste and the glass paste. The second conductive layer is patterned by a photolithography process. The photolithography process includes: a process of forming an etching mask by an exposure process and a development process; and a process of etching the second conductive layer using the etching mask.

[0067] Thus, a common wiring 21 is formed, consisting of a connecting portion 23, a detour portion 24, independent wiring regions 25a and 25c (the first layer 28 and the second layer 29 of the second independent wiring portion 27), a wiring layer 45, and multiple external connection terminals 50. The softening point of the planarization layer 15 is 800°C or higher. Therefore, when the first layer 28 is formed as silver wiring on the planarization layer 15, no bubbles are generated in the planarization layer 15, and no softening flow occurs. As a result, in the thermal printhead 1 of this embodiment 1, the generation of broken lines in the wiring layer 20 can be suppressed. Furthermore, the method for forming the wiring layer 20 is not limited to the method described above.

[0068] Next, the process of forming the heating resistor 30 is carried out (S5). In this process (S5), such as Figure 10 As shown, for example, a heating resistor 30 is formed on the heating glaze 12, the plurality of strip portions 22 of the common wiring 21, and the individual wiring regions 25b of the plurality of individual wirings 25. First, a resistor paste is applied to the heating glaze 12, the plurality of strip portions 22 of the common wiring 21, and the individual wiring regions 25b of the plurality of individual wirings 25. The resistor paste includes conductive materials such as ruthenium oxide, tantalum nitride, tantalum, or silver vanadium, as well as glass. Then, the resistor paste is calcined. In this way, the heating resistor 30 is formed.

[0069] Next, the process of forming the protective layer 33 (S6) is performed. In this process (S6), as... Figure 11 As shown, a protective layer 33 is formed on the glaze layer 11, the planarization layer 15, the wiring layer 20, and the heating resistor 30. Specifically, a glass paste that will become the first protective layer 34 is printed onto the glaze layer 11, the planarization layer 15, the wiring layer 20, and the heating resistor 30. The glass paste is then calcined. As a result, the first protective layer 34 is formed. Next, a glass paste that will become the second protective layer 35 is printed onto the first protective layer 34. This glass paste is then calcined. As a result, the second protective layer 35 is formed. Thus, the protective layer 33 is formed.

[0070] Next, a monolithization process (S7) is performed. In this process (S7), the laminate comprising the substrate 10, glaze layer 11, planarization layer 15, wiring layers 20 and 45, multiple external connection terminals 50, heating resistor 30, and protective layer 33 is divided. For example, grooves are formed on the substrate 10 using a laser scribing method. The laminate is then cut along the grooves. In this way, the laminate is monolithized.

[0071] Next, the process of mounting the drive circuit 40 is performed (S8). In this process (S8), as... Figure 12 As shown, a drive circuit 40 is mounted on the patch glaze 13. For example, the drive circuit 40 is fixed to the patch glaze 13 using a bonding component (not shown) such as resin adhesive or solder.

[0072] Next, the process of forming conductive lines 41 (S9) is performed. In this process (S9), as... Figure 13 As shown, conductive line 41 is joined. Conductive line 41 is joined to the drive circuit 40 and the individual wiring regions 25c of the plurality of individual wirings 25. Conductive line (not shown) is joined to the drive circuit 40 and the plurality of wiring layers 45.

[0073] Next, the process of forming the sealing member 43 is performed (S10). In this process (S10), the drive circuit 40 is sealed by the sealing member 43. For example, a sealing resin material is bonded to the drive circuit 40. The sealing resin material is then cured. Thus, the sealing member 43 is formed. In this way, a product is manufactured. Figures 1 to 3 The thermal printhead 1 of this embodiment 1 is shown. In the thermal printhead 1 of this embodiment 1, connectors may also be installed on multiple external connection terminals 50.

[0074] <Effects>

[0075] The thermal printhead 1 disclosed herein includes a substrate 10, an enamel layer 11, and a planarization layer 15. The substrate 10 has a first surface 10a. The enamel layer 11 is disposed on the first surface 10a. The planarization layer 15 is disposed on the first surface 10a. The planarization layer 15 includes crystalline portions 15b.

[0076] This suppresses the formation of bubbles and softening flow in the planarization layer 15. As a result, it suppresses wire breakage in the wiring layer 20.

[0077] According to the thermal printhead 1 described above, in the cross-section of the planarization layer 15, the crystalline portion 15b occupies an area of ​​more than 10% and less than 30% of the planarization layer 15.

[0078] This suppresses the surface roughness of the planarization layer 15 and inhibits the formation of bubbles and softening flow in the planarization layer 15. As a result, it suppresses wire breakage in the wiring layer 20.

[0079] The thermal printhead 1 described above includes a wiring layer 20 disposed on the planarization layer 15. The wiring layer 20 includes silver wiring.

[0080] This reduces the manufacturing cost of the thermal printhead 1.

[0081] According to the thermal printhead 1 described above, the planarization layer 15 includes an amorphous portion 15a.

[0082] This suppresses the surface roughness of the planarization layer 15 and inhibits the formation of bubbles and softening flow in the planarization layer 15. As a result, it suppresses wire breakage in the wiring layer 20.

[0083] According to the thermal printhead 1 described above, the material constituting the planarization layer 15 includes glass.

[0084] In this way, crystalline portions 15b can precipitate during the formation of planarization layer 15. As a result, the softening point of planarization layer 15 increases, and the generation of bubbles and softening flow in planarization layer 15 are suppressed. This helps to suppress wire breakage in wiring layer 20.

[0085] According to the thermal printhead 1 described above, the softening point of the planarization layer 15 is lower than that of the glaze layer 11.

[0086] In this way, after the glaze layer 11 is formed, a planarization layer 15 can be formed without softening the glaze layer 11.

[0087] According to the thermal printhead 1 described above, the softening point of the planarization layer 15 is above 800°C and below 870°C.

[0088] In this way, crystalline portions 15b can precipitate during the formation of planarization layer 15. As a result, the softening point of planarization layer 15 increases, and the generation of bubbles and softening flow in planarization layer 15 are suppressed. This helps to suppress wire breakage in wiring layer 20.

[0089] According to the thermal printhead 1 described above, the glaze layer 11 includes a heating glaze 12 and a patch glaze 13. The patch glaze 13 is disposed separately from the heating glaze 12. A planarization layer 15 (first planarization layer 16) is disposed between the heating glaze 12 and the patch glaze 13.

[0090] In this way, a wiring layer 20 can be formed on the first planarization layer 16 as a conductive path for energizing the heating resistor 30.

[0091] The various methods disclosed herein are summarized below as appendices.

[0092] (Postscript 1)

[0093] A thermal printhead, comprising:

[0094] A substrate having a first surface;

[0095] A glaze layer, which is disposed on the first surface; and

[0096] A planarization layer is disposed on the first surface.

[0097] The planarization layer includes crystalline portions.

[0098] (Postscript 2)

[0099] According to the thermal printhead described in Appendix 1, wherein...

[0100] In the cross-section of the planarization layer, the crystalline portion occupies an area of ​​more than 10% and less than 30% of the planarization layer.

[0101] (Note 3)

[0102] According to the thermal printhead described in Appendix 1 or Appendix 2, wherein,

[0103] It includes a wiring layer disposed on the planarization layer.

[0104] The wiring layer includes silver wiring.

[0105] (Note 4)

[0106] The thermal printhead according to any one of Appendices 1 to 3, wherein...

[0107] The planarization layer includes an amorphous portion.

[0108] (Note 5)

[0109] The thermal printhead according to any one of Appendices 1 to 4, wherein...

[0110] The material constituting the planarization layer includes glass.

[0111] (Note 6)

[0112] The thermal printhead according to any one of Appendices 1 to 5, wherein,

[0113] The softening point of the planarization layer is lower than that of the glaze layer.

[0114] (Note 7)

[0115] According to the thermal printhead described in Appendix 6, wherein...

[0116] The softening point of the planarization layer is above 800°C and below 870°C.

[0117] (Postscript 8)

[0118] The thermal printhead according to any one of Appendices 1 to 7, wherein...

[0119] The glaze layer includes a heated glaze and patch glazes spaced apart from the heated glaze.

[0120] The planarization layer is disposed between the heating glaze and the patch glaze.

[0121] Embodiments of the present invention have been described, but should be considered as illustrative rather than restrictive in all respects. The scope of the invention is defined by the claims, which are intended to include all changes within the meaning and scope equivalent to the claims.

Claims

1. A thermal printhead, characterized in that, have: A substrate having a first surface; A glaze layer, which is disposed on the first surface; and A planarization layer is disposed on the first surface. The planarization layer includes crystalline portions.

2. The thermal printhead according to claim 1, characterized in that, In the cross-section of the planarization layer, the crystalline portion occupies an area of ​​more than 10% and less than 30% of the planarization layer.

3. The thermal printhead according to claim 1 or 2, characterized in that, It includes a wiring layer disposed on the planarization layer. The wiring layer includes silver wiring.

4. The thermal printhead according to any one of claims 1 to 3, characterized in that, The planarization layer includes an amorphous portion.

5. The thermal printhead according to any one of claims 1 to 4, characterized in that, The material constituting the planarization layer includes glass.

6. The thermal printhead according to any one of claims 1 to 5, characterized in that, The softening point of the planarization layer is lower than that of the glaze layer.

7. The thermal printhead according to claim 6, characterized in that, The softening point of the planarization layer is above 800°C and below 870°C.

8. The thermal printhead according to any one of claims 1 to 7, characterized in that, The glaze layer includes a heated glaze and patch glazes spaced apart from the heated glaze. The planarization layer is disposed between the heating glaze and the patch glaze.

Images