Thermal print head, method for manufacturing thermal print head, and thermal printer

Abstract

A thermal print head (A10) comprises a substrate (1) having a substrate main surface (11) facing a first side in a thickness direction, a first glaze layer (21) disposed on the substrate main surface (11) and having a first glaze main surface (211) facing the first side, a band-form second glaze layer (22) disposed adjacent to the first glaze main surface (211) and extending in a main scanning direction, and a resistor layer (4) including a plurality of heat-generating parts aligned along the main scanning direction. The plurality of heat-generating parts are disposed on the second glaze layer (22).

Description

Thermal printhead, thermal printhead manufacturing method, and thermal printer

[0001] The present disclosure relates to a thermal printhead, a method for manufacturing the same, and a thermal printer including the thermal printhead.

[0002] Patent Document 1 discloses an example of a conventional thermal printhead. The thermal printhead described in Patent Document 1 has a glaze layer formed on a substrate. The glaze layer includes a partial glaze and a glass layer. The partial glaze is provided to facilitate pressing the heat-generating portion against the printing medium and to accumulate heat from the heat-generating portion, thereby improving printing efficiency. The glass layer is formed adjacent to and overlapping a portion of the partial glaze, and has a flat upper surface. The partial glaze is formed by disposing a glass paste on the main surface of the substrate by screen printing and then firing the glass paste. The glass layer is formed by thick-film printing of a glass paste on the substrate on which the partial glaze has been formed and then firing the glass paste. Further improvements in printing efficiency are desired for thermal printheads.

[0003] Japanese Patent Application Laid-Open No. 2021-115716

[0004] An object of the present disclosure is to provide an improved semiconductor device, and in particular, in view of the above-mentioned circumstances, an object of the present disclosure is to provide a thermal printhead that can further improve printing efficiency.

[0005] A thermal printhead according to one aspect of the present disclosure includes a substrate having a substrate main surface facing a first side in a thickness direction, a first glaze layer disposed on the substrate main surface and having a first glaze main surface facing the first side, a strip-shaped second glaze layer disposed in contact with the first glaze main surface and extending in a main scanning direction, and a resistor layer including a plurality of heating elements arranged along the main scanning direction, wherein the plurality of heating elements are disposed in the second glaze layer.

[0006] Another aspect of the present disclosure provides a method for manufacturing a thermal printhead, comprising: a substrate preparation step of preparing a substrate having a substrate main surface facing a first side in the thickness direction; a first placement step of placing a first glaze material on the substrate main surface; and a second placement step of placing a strip-shaped second glaze material extending in the main scanning direction on the first glaze material using a dispenser.

[0007] According to the above configuration, it is possible to further improve printing efficiency.

[0008] Other features and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.

[0009] FIG. 1 is a plan view showing a thermal printhead according to a first embodiment of the present disclosure. FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1. FIG. 3 is an enlarged plan view showing the thermal printhead of FIG. 1. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3. FIG. 5 is an enlarged view of FIG. 4. FIG. 6 is a flowchart showing an example of a method for manufacturing the thermal printhead shown in FIG. 1. FIG. 7 is a cross-sectional view showing a step of an example of a method for manufacturing the thermal printhead shown in FIG. 1. FIG. 8 is a cross-sectional view showing a step of an example of a method for manufacturing the thermal printhead shown in FIG. 1. FIG. 9 is a cross-sectional view showing a step of an example of a method for manufacturing the thermal printhead shown in FIG. 1. FIG. 10 is a cross-sectional view showing a step of an example of a method for manufacturing the thermal printhead shown in FIG. 1. FIG. 11 is a cross-sectional view showing a step of an example of a method for manufacturing the thermal printhead shown in FIG. 1. FIG. 12 is an enlarged cross-sectional view showing a thermal printhead according to a second embodiment of the present disclosure. FIG. 13 is a flowchart showing an example of a method for manufacturing the thermal printhead shown in FIG. 12. FIG. 14 is a cross-sectional view showing a step of an example of a method for manufacturing the thermal printhead shown in FIG. 12. FIG. 15 is a cross-sectional view showing a step of an example of a method for manufacturing the thermal printhead shown in FIG. 12 . FIG. 16 is a cross-sectional view showing a step of an example of a method for manufacturing the thermal printhead shown in FIG. 12 . FIG. 17 is a cross-sectional view showing a step of an example of a method for manufacturing the thermal printhead shown in FIG. 12 . FIG. 18 is a flowchart showing another example of a method for manufacturing the thermal printhead shown in FIG. 12 . FIG. 19 is an enlarged cross-sectional view showing a thermal printhead according to a third embodiment of the present disclosure. FIG. 20 is an enlarged cross-sectional view showing a thermal printhead according to a fourth embodiment of the present disclosure. FIG. 21 is a flowchart showing an example of a method for manufacturing the thermal printhead shown in FIG. 20 . FIG. 22 is a cross-sectional view showing a step of an example of a method for manufacturing the thermal printhead shown in FIG. 20 . FIG. 23 is a cross-sectional view showing a step of an example of a method for manufacturing the thermal printhead shown in FIG. 20 . FIG. 24 is a cross-sectional view showing a step of an example of a method for manufacturing the thermal printhead shown in FIG. 20 . FIG. 25 is an enlarged cross-sectional view showing a thermal printhead according to a first modified example of the fourth embodiment.FIG. 26 is an enlarged cross-sectional view showing a thermal printhead according to a second modification of the fourth embodiment.

[0010] Preferred embodiments of the present disclosure will now be described in detail with reference to the drawings.

[0011] In this disclosure, unless otherwise specified, "a certain object A is formed on a certain object B" and "a certain object A is formed on a certain object B" include "a certain object A is formed directly on a certain object B" and "a certain object A is formed on a certain object B with another object interposed between the certain object A and the certain object B." Similarly, "a certain object A is disposed on a certain object B" and "a certain object A is disposed on a certain object B" include "a certain object A is disposed directly on a certain object B" and "a certain object A is disposed on a certain object B with another object interposed between the certain object A and the certain object B" unless otherwise specified. Similarly, "a certain object A is located on a certain object B" includes "a certain object A is located on a certain object B with a certain object A in contact with the certain object B" and "a certain object A is located on a certain object B with another object interposed between the certain object A and the certain object B." Furthermore, unless otherwise specified, the phrase "an object A overlaps an object B when viewed from a certain direction" includes "an object A overlaps the entire object B" and "an object A overlaps a part of an object B."

[0012] First Embodiment: Figures 1 to 5 show a thermal printhead A10 according to a first embodiment of the present disclosure. The thermal printhead A10 of this embodiment includes a substrate 1, a glaze layer 2, an electrode layer 3, a resistor layer 4, a protective layer 5, a drive IC 71, a sealing resin 72, wires 73, a connector 74, and a heat dissipation member 75. The thermal printhead A10 is incorporated into a thermal printer B1 (see Figure 2), which prints on a print medium 82 that is conveyed between the platen roller 81 and the platen roller 81. The platen roller 81 is disposed opposite a heat generating unit 41 (described below) and presses the print medium 82 against the heat generating unit 41 while conveying the print medium 82. Examples of such print media 82 include thermal paper for producing barcode sheets and receipts.

[0013] FIG. 1 is a plan view of the thermal printhead A10. FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1. FIG. 3 is an enlarged plan view of the thermal printhead A10. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3. FIG. 5 is an enlarged view of FIG. 4. For ease of understanding, the protective layer 5 is omitted from FIGS. 1 and 3. In these figures, the longitudinal direction of the thermal printhead A10 is referred to as the main scanning direction x, the lateral direction as the sub-scanning direction y, and the thickness direction as the thickness direction z. Regarding the sub-scanning direction y, the lower side in FIGS. 1 and 3 (left side in FIG. 2) is referred to as the upstream side y1, where the print medium 82 is fed, and the upper side in FIGS. 1 and 3 (right side in FIG. 2) is referred to as the downstream side y2, where the print medium 82 is discharged. Regarding the thickness direction z, the upper side in FIGS. 2 and 4 is referred to as the first side z1, and the lower side in FIGS. 2 and 4 is referred to as the second side z2. 1 and 3 is defined as a first side x1, and the right side in Fig. 1 and 3 is defined as a second side x2 in the main scanning direction x. The same applies to the following figures.

[0014] The substrate 1 is made of a ceramic such as AlN, Al2O3, or zirconia. As shown in FIG. 1, the substrate 1 has a rectangular plate shape extending in the main scanning direction x when viewed in the thickness direction z. The thickness of the substrate 1 is not particularly limited, but is, for example, 0.6 mm to 1.0 mm. As shown in FIG. 4, the substrate 1 has a main surface 11 and a back surface 12. The main surface 11 and the back surface 12 face opposite each other in the thickness direction z. The main surface 11 faces a first side z1 in the thickness direction z. The back surface 12 faces a second side z2 in the thickness direction z. A glaze layer 2, an electrode layer 3, a resistor layer 4, and a protective layer 5 are disposed on the main surface 11 of the substrate 1. A driving IC 71 is mounted on the main surface 11. As shown in FIG. 2, a heat dissipation member 75 made of a metal such as Al is disposed on the back surface 12 of the substrate 1. As shown in FIGS. 1 and 2, a connector 74 is also disposed on the substrate 1. The connector 74 is connected to a connector of the thermal printer B1 when the thermal printhead A10 is incorporated into the thermal printer B1. There are no limitations on the materials and dimensions of the substrate 1 and the heat dissipation member 75. The thermal printhead A10 may also include a wiring board on the heat dissipation member 75 separate from the substrate 1, with the driver IC 71 and connector 74 mounted on the wiring board.

[0015] The glaze layer 2 is disposed on the main surface 11 of the substrate 1 and is made of a glass material such as amorphous glass. The glaze layer 2 is formed by disposing a glass paste and then firing it. In this embodiment, the entire main surface 11 of the substrate 1 is covered with the glaze layer 2. Note that the glaze layer 2 may be configured so as not to cover a portion of the main surface 11. In this embodiment, as shown in FIGS. 4 and 5 , the glaze layer 2 includes a first glaze layer 21, a second glaze layer 22, and a die bonding glaze 24.

[0016] The first glaze layer 21 is disposed in contact with the main surface 11 of the substrate 1, and in this embodiment, is disposed over the entire main surface 11. The first glaze layer 21 has a main surface 211. The main surface 211 faces a first side z1 in the thickness direction z and is flat over the entire surface. The first glaze layer 21 is provided to eliminate irregularities on the main surface 11 of the substrate 1, making it easier to stack the electrode layer 3. The thickness of the first glaze layer 21 (dimension in the thickness direction z) is, for example, approximately 10 to 20 μm. The thickness of the first glaze layer 21 is not limited. The softening point T1 of the first glaze material, which is the glass material of the first glaze layer 21, is, for example, approximately 1200 to 1300° C. The softening point T1 is not limited. The first glaze layer 21 is formed, for example, by applying a glass paste to the main surface 11 of the substrate 1 by screen printing and then firing the paste. The method for forming the first glaze layer 21 is not limited.

[0017] The second glaze layer 22 is disposed in contact with the main surface 211 of the first glaze layer 21. The second glaze layer 22 extends in the main scanning direction x and is band-shaped when viewed in the thickness direction z. The second glaze layer 22 is disposed downstream y2 of the main surface 211 of the first glaze layer 21 in the sub-scanning direction y. The second glaze layer 22 has a main surface 221. The main surface 221 faces a first side z1 in the thickness direction z and is curved over substantially the entire surface. The cross section of the second glaze layer 22 perpendicular to the main scanning direction x bulges toward the first side z1 in the thickness direction z. The second glaze layer 22 is provided to facilitate pressing the heating portion 41 of the resistor layer 4 against the print medium 82, etc. The second glaze layer 22 also functions as a heat storage layer that accumulates heat generated by the heating portion 41. The thickness of second glaze layer 22 (dimension in thickness direction z) is, for example, approximately 100 to 200 μm. The thickness of second glaze layer 22 is not limited. The softening point T2 of the second glaze material, which is the glass material of second glaze layer 22, is lower than the softening point T1 of the first glaze material, and is, for example, approximately 850 to 1000° C. The softening point T2 is not limited. Second glaze layer 22 is formed by applying glass paste with a dispenser to main surface 211 of first glaze layer 21 formed by firing, and then firing the applied paste.

[0018] The dispenser's discharge port is a slit nozzle, and the long side dimension of the slit (the dimension in the sub-scanning direction y when depositing the glass paste) is set according to the width dimension (the dimension in the sub-scanning direction y) of the second glaze layer 22 to be deposited. The dispenser's discharge amount is set by setting the short side dimension of the slit (the dimension perpendicular to the long side) according to the thickness dimension (the dimension in the thickness direction z) of the second glaze layer 22 to be deposited. The thickness dimension of the second glaze layer 22 is fine-tuned by adjusting the dispenser's discharge pressure and movement speed. In this way, the dispenser can adjust the dimension of the glass paste to be deposited by adjusting the slit dimensions, discharge pressure, movement speed, etc., and can deposit glass paste in thickness dimensions that are difficult to achieve by screen printing.

[0019] The die bonding glaze 24 is disposed in contact with the main surface 211 of the first glaze layer 21, and is spaced apart from the second glaze layer 22 on the upstream side y1 in the sub-scanning direction y. The die bonding glaze 24 is a strip extending in the main scanning direction x and parallel (or approximately parallel) to the second glaze layer 22. The die bonding glaze 24 supports a portion of the electrode layer 3 and the drive IC 71. The thickness of the die bonding glaze 24 (dimension in the thickness direction z) is, for example, approximately 30 to 50 μm. The thickness of the die bonding glaze 24 is not limited. The softening point of the glass material of the die bonding glaze 24 is lower than the softening point T1 of the glass material of the first glaze layer 21, and is, for example, approximately 850°C. The softening point of the glass material of the die bonding glaze 24 is not limited. The die bonding glaze 24 is formed by applying a glass paste by screen printing, for example, to the main surface 211 of the first glaze layer 21 formed by firing, and then firing the applied paste. Note that there are no limitations on the method for forming the die bonding glaze 24. Furthermore, the glaze layer 2 does not necessarily need to include the die bonding glaze 24.

[0020] The electrode layer 3, which forms a path for conducting current to the resistor layer 4, is made of a conductive material. The electrode layer 3 is made of, for example, Au resinate doped with rhodium, vanadium, bismuth, silicon, or other additive elements. The electrode layer 3 is formed by thick-film printing of an Au resinate paste and then firing the resulting paste. The electrode layer 3 may also be formed by stacking multiple Au layers. The thickness of the electrode layer 3 is, for example, 0.3 μm to 1.5 μm. The material, formation method, and thickness of the electrode layer 3 are not limited. In this embodiment, the electrode layer 3 is disposed on the glaze layer 2. As shown in FIG. 3 , the electrode layer 3 includes a common electrode 33 and multiple individual electrodes 36. For ease of understanding, the common electrode 33 and the individual electrodes 36 are hatched in FIG. 3 . Similarly, the Ag layer 351 (described later) is also hatched, and the resistor layer 4 is dotted.

[0021] The common electrode 33 has a plurality of common electrode strip portions 34 and a connecting portion 35. The connecting portion 35 is arranged near the downstream end y2 of the substrate 1 in the sub-scanning direction y and has a strip shape extending in the main scanning direction x. The plurality of common electrode strip portions 34 each extend from the connecting portion 35 in the sub-scanning direction y and are spaced apart at equal intervals in the main scanning direction x. In this embodiment, an Ag layer 351 is laminated on the connecting portion 35. The Ag layer 351 is intended to reduce the resistance value of the connecting portion 35. The thickness of the Ag layer 351 is, for example, 2 μm or more and 10 μm or less.

[0022] The individual electrodes 36 are used to partially energize the resistor layer 4, and are portions having an opposite polarity to the common electrode 33. The individual electrodes 36 extend from the resistor layer 4 toward the driving IC 71. The individual electrodes 36 are arranged in the main scanning direction x, and each has an individual electrode strip portion 38, a connecting portion 37, and a bonding portion 39.

[0023] Each individual electrode strip portion 38 is a strip-shaped portion extending in the sub-scanning direction y and is disposed between any two adjacent common electrode strip portions 34 of the common electrode 33. The distance between the individual electrode strip portion 38 of adjacent individual electrodes 36 and the common electrode strip portion 34 of the common electrode 33 is, for example, 40 μm or less. The center-to-center distance between the individual electrode strip portion 38 of adjacent individual electrodes 36 and the common electrode strip portion 34 of the common electrode 33 is, for example, 20 μm or more and 100 μm or less.

[0024] The connecting portion 37 is a portion that extends from the individual electrode strip portion 38 toward the driving IC 71. The connecting portion 37 has a parallel portion 371 and an oblique portion 372. One end of the parallel portion 371 is connected to the bonding portion 39 and extends along the sub-scanning direction y. The oblique portion 372 is inclined with respect to the sub-scanning direction y. The oblique portion 372 is sandwiched between the parallel portion 371 and the individual electrode strip portion 38 in the sub-scanning direction y. Furthermore, the multiple individual electrodes 36 are collected at the driving IC 71.

[0025] The bonding portion 39 is disposed at the upstream end (y1) of the individual electrode 36 in the sub-scanning direction y and is connected to the parallel portion 371. A wire 73 is bonded to the bonding portion 39 for electrically connecting the individual electrode 36 to the driving IC 71. The multiple bonding portions 39 include a first bonding portion 39A and a second bonding portion 39B. The width (dimension in the main scanning direction x) of the parallel portion 371 sandwiched between two adjacent first bonding portions 39A is, for example, 20 μm or more and 30 μm or less. The second bonding portion 39B is located farther from the resistor layer 4 (upstream side y1) than the first bonding portion 39A in the sub-scanning direction y. The second bonding portion 39B is connected to the parallel portion 371 sandwiched between two adjacent first bonding portions 39A. This configuration prevents the bonding portions 39 from interfering with each other, even though they are wider than most of the connecting portion 37. The portion of the connecting portion 37 sandwiched between adjacent first bonding portions 39A is the narrowest in the individual electrode 36.

[0026] The shape and arrangement of each part of the electrode layer 3 are not particularly limited, and various configurations are possible. The material of each part of the electrode layer 3 is also not limited.

[0027] The resistor layer 4 is made of a material having a higher resistivity than the material constituting the electrode layer 3, such as ruthenium oxide. The resistor layer 4 is disposed on the second glaze layer 22 and formed in a strip shape extending in the primary scanning direction x. The resistor layer 4 is formed by thick-film printing of a paste such as ruthenium oxide and then firing the resulting film. The resistor layer 4 intersects and contacts the common electrode strip portions 34 of the common electrode 33 and the individual electrode strip portions 38 of the individual electrodes 36. The resistor layer 4 is also laminated on the opposite side of the substrate 1 (first side z1 in the thickness direction z) from the common electrode strip portions 34 of the common electrode 33 and the individual electrode strip portions 38 of the individual electrodes 36. Portions of the resistor layer 4 sandwiched between the common electrode strip portions 34 and the individual electrode strip portions 38 form heat-generating portions 41 that generate heat when partially energized by the electrode layer 3. The plurality of heat generating portions 41 are disposed in the second glaze layer 22 and are arranged in the main scanning direction x. As shown in FIG. 2, in the thermal printer B1, the plurality of heat generating portions 41 face the platen roller 81. Print dots are formed by the heat generated by the heat generating portions 41. The thickness of the resistor layer 4 is, for example, 1 μm to 10 μm, and preferably 3 μm to 10 μm. The material and thickness of the resistor layer 4 are not limited.

[0028] The protective layer 5 protects the electrode layer 3 and the resistor layer 4 and covers almost the entire electrode layer 3 and the resistor layer 4. However, the protective layer 5 leaves exposed an area including the bonding portions 39 of the multiple individual electrodes 36. The protective layer 5 is made of a glass material such as amorphous glass. The protective layer 5 is formed by thick-film printing of a glass paste and then firing the printed layer. The thickness of the protective layer 5 is, for example, 0.5 μm to 10 μm. The material, formation method, and thickness of the protective layer 5 are not limited. The thermal printhead A10 may further include a second protective layer that covers a portion of the protective layer 5.

[0029] The driving IC 71 functions to partially heat the resistor layer 4 by selectively energizing the multiple individual electrodes 36. As shown in FIG. 4 , multiple driving ICs 71 are disposed on the die bonding glaze 24. The driving IC 71 has multiple pads. The pads of the driving IC 71 are connected to the multiple individual electrodes 36 via multiple wires 73 bonded to each pad. The wires 73 are made of, for example, Au. As shown in FIGS. 1 and 2 , the driving IC 71 and wires 73 are covered with a sealing resin 72. The sealing resin 72 is made of, for example, a black insulating soft resin. The driving IC 71 and connector 74 are connected via the wires 73 and wiring on the substrate 1.

[0030] Next, an example of a method for manufacturing the thermal printhead A10 will be described below with reference to Figures 6 to 11. Figure 6 is a flowchart showing an example of a method for manufacturing the thermal printhead A10. Figures 7 to 11 are cross-sectional views showing one step of an example of a method for manufacturing the thermal printhead A10, and correspond to the cross section shown in Figure 4. The main scanning direction x, sub-scanning direction y, and thickness direction z shown in Figures 6 to 11 indicate the same directions as in Figures 1 to 5.

[0031] As shown in FIG. 6, the manufacturing method for the thermal printhead A10 includes a substrate preparation process S10, a glaze layer formation process S20, an electrode layer formation process S30, a resistor layer formation process S40, a protective layer formation process S50, a driver IC mounting and sealing process S60, and an attachment process S70.

[0032] First, a substrate 1 made of, for example, AlN, Al2O3, or zirconia is prepared (substrate preparation step S10). The substrate 1 has a main surface 11 and a back surface 12 facing opposite sides in the thickness direction z. The main surface 11 faces a first side z1 in the thickness direction z. The back surface 12 faces a second side z2 in the thickness direction z.

[0033] Next, a glaze layer 2 is formed on the substrate 1 as shown in FIGS. 7 to 10 (glaze layer forming step S20). In this step, a glass paste of a first glaze material is first applied over the entire main surface 11 of the substrate 1 by screen printing (first application step S21). The glass paste is then fired to form a first glaze layer 21 on the main surface 11 as shown in FIG. 7 (first firing step S22). The main surface 211 of the first glaze layer 21 is flat across its entire surface. Next, glass paste is applied to predetermined positions on the main surface 211 of the first glaze layer 21 by screen printing and then fired to form a die bonding glaze 24 on the main surface 211 as shown in FIG. 8.

[0034] Next, as shown in FIG. 9 , a dispenser is used to deposit glass paste 22A, the second glaze material, in a strip shape extending in the main scanning direction x at a predetermined position on the main surface 211 of the first glaze layer 21 (second depositing step S23). By depositing the glass paste 22A using a dispenser, the thickness of the glass paste 22A is greater than that achieved by screen printing. The glass paste 22A is then dried, resulting in the second glaze material being deposited on the main surface 211 of the first glaze layer 21. Due to the coffee ring effect during drying, a recess extending in the main scanning direction x is formed in the center of the second glaze material as viewed in the thickness direction z.

[0035] Next, the second glaze material is fired to form a second glaze layer 22 on the main surface 211 of the first glaze layer 21, as shown in FIG. 10 (second firing step S24). Due to the surface tension of the softened second glaze material, the main surface 221 of the second glaze layer 22 is curved, protruding toward the first side z1 in the thickness direction z. Therefore, as shown in FIG. 10, the cross section of the second glaze layer 22 perpendicular to the main scanning direction x bulges toward the first side z1 in the thickness direction z. Furthermore, by setting the firing temperature in the second firing step S24 to a temperature between the softening points T1 and T2, only the second glaze material can be fired without softening the first glaze layer 21. In this manner, a glaze layer 2 is formed on the substrate 1.

[0036] Next, a resinate Au paste is thick-film printed and then fired to form a metal film. The metal film is then patterned, for example, by etching. As a result, an electrode layer 3 is formed on the glaze layer 2, as shown in FIG. 11 (electrode layer formation step S30). Next, a paste containing Ag is thick-film printed in a predetermined region on the connecting portion 35 of the electrode layer 3, and then fired. As a result, an Ag layer 351 is formed, as shown in FIG. 11. Next, a resistor paste containing a resistor, such as ruthenium oxide, is thick-film printed and then fired. As a result, a resistor layer 4 is formed, as shown in FIG. 11 (resistor layer formation step S40).

[0037] Next, a protective layer 5 is formed by printing a thick film of glass paste, for example, and baking it (protective layer forming step S50). Next, the driver IC 71 is mounted, wires 73 are bonded, and a sealing resin 72 is formed (driver IC mounting and sealing step S60). Then, a connector 74 is attached to the substrate 1, and the substrate 1 is attached to a heat dissipation member 75 (attaching step S70). In this way, the thermal printhead A10 shown in FIGS. 1 to 5 is manufactured. The above-mentioned manufacturing method is an example, and the present invention is not limited to this.

[0038] Next, the operation of the thermal printhead A10 will be described.

[0039] In this embodiment, the glaze layer 2 of the thermal printhead A10 includes a second glaze layer 22. The second glaze layer 22 is formed by applying a glass paste 22A using a dispenser to the main surface 211 of the first glaze layer 21, which is disposed on the main surface 11 of the substrate 1, and then firing the applied glass paste. Therefore, the thickness of the second glaze layer 22 can be increased compared to when glass paste applied by screen printing is fired. This makes it easier for the thermal printhead A10 to press the heat generating portion 41 against the print medium 82, etc., and efficiently transfers heat generated by the heat generating portion 41 to the print medium 82. Furthermore, because the second glaze layer 22 can store more heat generated by the heat generating portion 41, the thermal printhead A10 can reduce the amount of heat that must be generated by the heat generating portion 41. Therefore, the thermal printhead A10 can reduce power consumption and further improve printing efficiency.

[0040] Furthermore, in this embodiment, the second glaze layer 22 is formed on the main surface 211 of the first glaze layer 21 formed by firing in the first firing step S22. Therefore, the thermal printhead A10 can position the heat generating portion 41 farther away from the main surface 11 of the substrate 1 in the thickness direction z than if the second glaze layer 22 were formed on the substrate 1 first and then the first glaze layer 21 were formed adjacent to the second glaze layer 22. This makes it easier for the thermal printhead A10 to press the heat generating portion 41 against the print medium 82, etc.

[0041] In this embodiment, the softening point T2 of the second glaze material is lower than the softening point T1 of the first glaze material. Therefore, by setting the firing temperature in the second firing step S24 to a temperature between the softening points T1 and T2, it is possible to fire only the second glaze material without softening the first glaze layer 21.

[0042] 12 to 26 show other embodiments of the present disclosure. In these figures, elements that are the same as or similar to those in the above embodiment are denoted by the same reference numerals as those in the above embodiment.

[0043] Second Embodiment: FIGS. 12 to 17 are diagrams illustrating a thermal printhead A20 according to a second embodiment of the present disclosure. FIG. 12 is an enlarged cross-sectional view of the thermal printhead A20, corresponding to FIG. 5. FIG. 13 is a flowchart illustrating an example of a method for manufacturing the thermal printhead A20, corresponding to FIG. 6. Note that FIG. 13 only illustrates the glaze layer formation step S20, omitting other steps. FIGS. 14 to 17 are cross-sectional views illustrating a step of an example of a method for manufacturing the thermal printhead A20, corresponding to FIGS. 9 and 10. The thermal printhead A20 of this embodiment differs from the above-described embodiment in that the glaze layer 2 further includes a third glaze layer 23. The configuration and operation of other parts of this embodiment are similar to those of the first embodiment. Note that the components of the first embodiment may be combined in any desired manner.

[0044] As shown in FIG. 12 , the second glaze layer 22 according to this embodiment includes regions 22a, 22b, and 22c. The regions 22a, 22b, and 22c each have the same shape as the second glaze layer 22 according to the first embodiment and extend in the main scanning direction x. The regions 22a, 22b, and 22c are spaced apart from one another in the sub-scanning direction y. In this embodiment, the glaze layer 2 further includes a third glaze layer 23. The third glaze layer 23 is interposed between the second glaze layer 22 and the plurality of heat generating portions 41 and covers the entire second glaze layer 22 (regions 22a, 22b, and 22c). The third glaze layer 23 does not necessarily have to cover a portion of the second glaze layer 22. The third glaze layer 23 extends in the main scanning direction x and is strip-shaped when viewed in the thickness direction z. The softening point T3 of the third glaze material, which is the glass material of the third glaze layer 23, is lower than the softening point T2 of the second glaze material, and is, for example, about 850°C.

[0045] 13, the method for manufacturing the thermal printhead A20 further includes a glaze layer forming step S20, a third disposing step S25, and a third baking step S26. The steps other than the glaze layer forming step S20 (S10, S30 to S70) are the same as those in the first embodiment.

[0046] In the glaze layer forming step S20, the first disposing step S21, the first firing step S22, and the step of forming the die bonding glaze 24 are the same as those in the first embodiment (see FIGS. 7 and 8 ). In the second disposing step S23, the disposing of the glass paste 22A by the dispenser is repeated three times, so that three strip-shaped glass pastes 22A extending in the main scanning direction x are disposed at a distance from each other, as shown in FIG.

[0047] Next, the second glaze material, which is made by drying the glass paste 22A, is fired to form the second glaze layer 22 (regions 22a, 22b, 22c) on the main surface 211 of the first glaze layer 21, as shown in Figure 15 (second firing step S24).

[0048] Next, as shown in FIG. 16 , a glass paste 23A of a third glaze material is placed using a dispenser to cover the entire second glaze layer 22 (regions 22a, 22b, and 22c) (third placement step S25). The glass paste 23A is placed in a strip shape extending in the main scanning direction x. The surface of the glass paste 23A has projections and depressions formed thereon in accordance with the shapes of the regions 22a, 22b, and 22c. After that, the glass paste 23A dries, resulting in the third glaze material being placed to cover the second glaze layer 22 (regions 22a, 22b, and 22c).

[0049] Next, the third glaze material is fired to form a third glaze layer 23 covering the second glaze layer 22 (regions 22a, 22b, and 22c) (third firing step S26), as shown in Fig. 17. Due to the surface tension of the softened third glaze material, the third glaze layer 23 has a curved shape with its main surface 231 protruding toward the first side z1 in the thickness direction z. Furthermore, by setting the firing temperature in the third firing step S26 to a temperature between the softening points T2 and T3, only the third glaze material can be fired without softening the second glaze layer 22.

[0050] In this embodiment, the thermal printhead A20 also achieves the same effects as the thermal printhead A10. Furthermore, in this embodiment, the glaze layer 2 of the thermal printhead A20 includes a second glaze layer 22 (regions 22a, 22b, and 22c) and a third glaze layer 23. Hereinafter, the combination of the second glaze layer 22 (regions 22a, 22b, and 22c) and the third glaze layer 23 may be referred to as a "partial glaze." The partial glaze is formed by covering the second glaze layer 22 (regions 22a, 22b, and 22c) with the third glaze layer 23, and is thicker than the second glaze layer 22. Therefore, compared to the thermal printhead A10, the thermal printhead A20 can further reduce power consumption and further improve printing efficiency. Furthermore, the second glaze layer 22 includes regions 22a, 22b, and 22c spaced apart in the sub-scanning direction y. Therefore, the dimension of the partial glaze in the sub-scanning direction y can be made larger than that of the second glaze layer 22 according to the first embodiment. This allows the volume of the partial glaze to be increased, allowing more heat to be accumulated from the heat generating portion 41. This allows the thermal printhead A20 to further improve printing efficiency.

[0051] Furthermore, in this embodiment, the third glaze layer 23 is formed so as to cover the second glaze layer 22 formed by firing in the second firing step S24. Therefore, compared to the thermal printhead A10, the heat generating portion 41 of the thermal printhead A20 can be positioned farther away from the main surface 11 of the substrate 1 in the thickness direction z. This makes it easier for the heat generating portion 41 of the thermal printhead A20 to be pressed against the print medium 82 or the like.

[0052] In this embodiment, the softening point T3 of the third glaze material is lower than the softening point T2 of the second glaze material. Therefore, by setting the firing temperature in the third firing step S26 to a temperature between the softening points T2 and T3, only the third glaze material can be fired without softening the second glaze layer 22.

[0053] In this embodiment, the second glaze layer 22 includes three regions 22 a, 22 b, and 22 c, but this is not limiting. The second glaze layer 22 may include two regions, or four or more regions. The greater the number of regions included in the second glaze layer 22, the larger the dimension of the partial glaze in the sub-scanning direction y can be.

[0054] In this embodiment, the second glaze layer 22 (regions 22a, 22b, and 22c) is formed in the second baking step S24, and then the third glaze material is placed in the third placement step S25. However, this is not limited to this. For example, as shown in FIG. 18 , after the second placement step S23, the third glaze material may be placed in the third placement step S25, and then the second and third glaze materials may be fired together in the second baking step S24. In this case, the softening point T3 of the third glaze material may be set to be the same as (or approximately the same as) the softening point T2 of the second glaze material.

[0055] Third Embodiment: Figure 19 is a diagram illustrating a thermal printhead A30 according to a third embodiment of the present disclosure. Figure 19 is an enlarged cross-sectional view of the thermal printhead A30, corresponding to Figure 5. The thermal printhead A30 of this embodiment differs from the second embodiment described above in that the second glaze layer 22 consists of a single region. The configuration and operation of other parts of this embodiment are similar to those of the second embodiment. Note that the parts of the first and second embodiments described above may be combined in any desired manner.

[0056] Unlike the second embodiment, the second glaze layer 22 according to this embodiment does not include multiple regions, and has a configuration similar to that of the second glaze layer 22 according to the first embodiment. Also, in this embodiment, as in the second embodiment, the glaze layer 2 includes a third glaze layer 23. The third glaze layer 23 has a configuration similar to that of the third glaze layer 23 according to the second embodiment. The method for manufacturing the thermal printhead A30 is the same as the method for manufacturing the thermal printhead A20, except that the glass paste 22A is placed only once in the second placement step S23.

[0057] In this embodiment, the thermal printhead A30 also achieves the same effects as the thermal printhead A10. Furthermore, in this embodiment, the glaze layer 2 of the thermal printhead A30 includes a partial glaze (a combination of the second glaze layer 22 and the third glaze layer 23). The partial glaze is formed by covering the second glaze layer 22 with the third glaze layer 23, and is thicker than the second glaze layer 22. Therefore, compared to the thermal printhead A10, the thermal printhead A30 can further reduce power consumption and further improve printing efficiency.

[0058] Furthermore, in this embodiment, the third glaze layer 23 is formed so as to cover the second glaze layer 22 formed by firing in the second firing step S24. Therefore, compared to the thermal printhead A10, the thermal printhead A30 can position the heat generating portion 41 farther in the thickness direction z from the main surface 11 of the substrate 1. This makes it easier for the thermal printhead A30 to press the heat generating portion 41 against the print medium 82, etc.

[0059] In this embodiment, the softening point T3 of the third glaze material is lower than the softening point T2 of the second glaze material. Therefore, by setting the firing temperature in the third firing step S26 to a temperature between the softening points T2 and T3, only the third glaze material can be fired without softening the second glaze layer 22.

[0060] Fourth Embodiment: FIGS. 20 to 24 are diagrams illustrating a thermal printhead A40 according to a fourth embodiment of the present disclosure. FIG. 20 is an enlarged cross-sectional view of the thermal printhead A40, further enlarging the view corresponding to FIG. 5. FIG. 21 is a flowchart illustrating an example of a method for manufacturing the thermal printhead A40, corresponding to FIG. 6. Note that FIG. 21 only illustrates the glaze layer formation step S20, omitting other steps. FIGS. 22 to 24 are cross-sectional views illustrating a step of an example of a method for manufacturing the thermal printhead A40. The thermal printhead A40 of this embodiment differs from the first embodiment described above in that a recess is formed in the first glaze layer 21 and the second glaze layer 22 is disposed in this recess. The configuration and operation of other parts of this embodiment are similar to those of the first embodiment. Note that the parts of the first to third embodiments described above may be combined in any desired manner.

[0061] The first glaze layer 21 according to this embodiment includes a recess 212. The recess 212 is a groove recessed from the main surface 211 toward the second side z2 in the thickness direction z and extends linearly in the main scanning direction x. When viewed in the thickness direction z, the recess 212 has an elongated rectangular shape extending elongatedly in the main scanning direction x. The depth dimension (dimension in the thickness direction z) of the recess 212 is not limited. The recess 212 is formed, for example, by wet blasting. Wet blasting is a processing technique for processing an object by accelerating a slurry containing an abrasive and water (sometimes containing chemicals) with compressed air and spraying it toward the object. As described below, the recess 212 is formed by forming a mask layer on the main surface 211 and then performing wet blasting on the areas of the main surface 211 where the mask layer is not formed. The method for forming the recess 212 is not limited. The recess 212 may be formed, for example, by shot blasting other than wet blasting, by etching, or by cutting with a dicing blade or laser. The recess 212 has two recess edges 212a. Each recess edge 212a is a boundary between the recess 212 and the main surface 211 and extends in the main scanning direction x. The inclination angle α of the side surface 212b of the recess 212 with respect to the main surface 211 is approximately a right angle. Note that the inclination angle α is not limited to being approximately a right angle.

[0062] In this embodiment, the second glaze layer 22 is disposed inside the recess 212 as viewed in the thickness direction z. The second glaze layer 22 is formed by disposing a glass paste in the recess 212 and firing the glass paste. Although the glass paste has fluidity, when disposed in the recess 212, surface tension prevents it from flowing beyond the recess edge 212a. Furthermore, during firing, the glass paste becomes fluid due to heating, but surface tension prevents it from flowing beyond the recess edge 212a. The recess 212 only needs to have a recess edge 212a to prevent the glass paste from flowing and spreading over the main surface 211. Therefore, the depth of the recess 212 may be relatively small. Furthermore, it is desirable for the inclination angle α to be relatively large. As viewed in the thickness direction z, the glaze edge 222, which is the edge of the second glaze layer 22 in the sub-scanning direction y, and the recess edge 212a of the recess 212 coincide with each other. More specifically, the glaze edge 222 on the upstream side y1 in the sub-scanning direction y coincides with the recess edge 212a on the upstream side y1 in the sub-scanning direction y, and the glaze edge 222 on the downstream side y2 in the sub-scanning direction y coincides with the recess edge 212a on the downstream side y2 in the sub-scanning direction y. The second glaze layer 22 is formed such that its formation area is defined by the recess 212.

[0063] 21, the method for manufacturing the thermal printhead A40 adds a recess forming step S27 between the first firing step S22 and the second placement step S23. The steps (S10, S30 to S70) other than the glaze layer forming step S20 are the same as those in the first embodiment.

[0064] In the glaze layer forming step S20, the first placement step S21, the first firing step S22, and the step of forming the die bonding glaze 24 are the same as those in the first embodiment (see FIGS. 7 and 8). Next, as shown in FIG. 22, a recess 212 is formed in the first glaze layer 21 (recess forming step S27).

[0065] In the recess formation process S27, a predetermined mask layer 99 (shown by a two-dot chain line in FIG. 22 ) is first formed on a portion of the main surface 211 of the first glaze layer 21. The mask layer 99 is formed, for example, by patterning a resist using photolithography. The mask layer 99 has an opening 99a that penetrates the mask layer 99 in the thickness direction z and extends in the main scanning direction x. Next, wet blasting is performed to form a recess 212 that is recessed from the main surface 211 in the thickness direction z and extends in the main scanning direction x, as shown in FIG. 22 . The shape of the recess 212 as viewed in the thickness direction z corresponds to the shape of the opening 99a in the mask layer 99. The recess 212 has a bottom surface 212c facing the first side z1 in the thickness direction z. The bottom surface 212c has irregularities formed by wet blasting. The mask layer 99 is then removed.

[0066] 23, in the second disposing step S23, a glass paste 22A of the second glaze material is dispensed into the recess 212 of the first glaze layer 21 using a dispenser. The dispensed glass paste 22A has fluidity, but surface tension prevents it from going beyond the edge 212a of the recess. The method for disposing the glass paste 22A is not limited, and it may be disposed by screen printing, for example.

[0067] 24, in the second firing step S24, the second glaze layer 22 is formed in the recess 212 of the first glaze layer 21. The glass paste 22A is fluidized by the heat during firing, but surface tension prevents it from flowing over the edge 212a of the recess. As a result, the second glaze layer 22 is formed with the glaze edge 222 and the edge 212a of the recess aligned in the thickness direction z.

[0068] In this embodiment, the thermal printhead A40 also achieves the same effects as the thermal printhead A10. Furthermore, in this embodiment, the first glaze layer 21 includes a recess 212 recessed from the main surface 211 toward the second side z2 in the thickness direction z and extending in the main scanning direction x. The second glaze layer 22 is disposed inside the recess 212 as viewed in the thickness direction z. The second glaze layer 22 is formed during the manufacturing process by preventing the flowable glass paste 22A from exceeding the recess edge 212a of the recess 212. This prevents the second glaze layer 22 from spreading over the main surface 211 and is formed in the formation region defined by the recess 212. Therefore, the thermal printhead A40 can linearize each glaze edge 222 of the second glaze layer 22. The thermal printhead A40 can also prevent the second glaze layer 22 from spreading over the main surface 211 and reducing its thickness.

[0069] According to this embodiment, the recesses 212 are formed by wet blasting. Therefore, the recesses 212 can be easily formed in a short time. Furthermore, the recesses 212 can be formed so that the inclination angle α is approximately a right angle.

[0070] 25 and 26 show modified examples of the thermal printhead A40 according to the fourth embodiment. In these figures, elements that are the same as or similar to those in the above embodiment are given the same reference numerals as in the above embodiment, and redundant explanations will be omitted.

[0071] First Modification: Fig. 25 is a diagram illustrating a thermal printhead A41 according to a first modification of the fourth embodiment. Fig. 25 is an enlarged cross-sectional view of the thermal printhead A41, and corresponds to Fig. 20. The recess 212 according to this modification is made up of two grooves 213 aligned in the sub-scanning direction y.

[0072] Each groove 213 is recessed from the main surface 211 toward the second side z2 in the thickness direction z and extends in the main scanning direction x. When viewed in the thickness direction z, each groove 213 has an elongated rectangular shape extending long in the main scanning direction x. Each groove 213 is formed, for example, by wet blasting. Note that the method for forming each groove 213 is not limited. Each groove 213 has a recess edge 213a and a recess edge 213b. The recess edge 213a and the recess edge 213b are boundaries between each groove 213 and the main surface 211 and extend in the main scanning direction x. The recess edge 213a is an edge located on the opposite side from the other groove 213 in the sub-scanning direction y. The recess edge 213b is an edge located on the side of the other groove 213 in the sub-scanning direction y.

[0073] The main surface 211 is divided into three regions by the recess 212 (two grooves 213). Each of the three regions has an elongated rectangular shape extending long in the main scanning direction x. The main surface 211 includes a land portion 211a. The land portion 211a is one of the three regions and is located between two of the grooves 213. In other words, the land portion 211a is connected to the groove 213 via the recess edge 213b.

[0074] The second glaze layer 22 is disposed on the land 211a of the main surface 211 and in each groove 213 as viewed in the thickness direction z. The glass paste 22A, which is the material of the second glaze layer 22, is fluid, but when disposed in the first glaze layer 21, surface tension prevents it from flowing over the recessed edge 213a. The glass paste 22A also becomes fluid when heated during firing, but surface tension prevents it from flowing over the recessed edge 213a. As viewed in the thickness direction z, the glaze edge 222 and the recessed edge 213a coincide with each other. More specifically, the glaze edge 222 on the upstream side y1 in the sub-scanning direction y coincides with the recessed edge 213a of the groove 213 on the upstream side y1 in the sub-scanning direction y, and the glaze edge 222 on the downstream side y2 in the sub-scanning direction y coincides with the recessed edge 213a of the groove 213 on the downstream side y2 in the sub-scanning direction y. The second glaze layer 22 is formed in a region defined by the recess edges 213 a of the grooves 213 of the recess 212 .

[0075] According to this modification, the first glaze layer 21 includes a recess 212 recessed from the main surface 211 toward the second side z2 in the thickness direction z and consisting of two grooves 213 extending in the main scanning direction x. The second glaze layer 22 is disposed on the inter-groove portions 211 a of the main surface 211 and in each groove 213 as viewed in the thickness direction z. The second glaze layer 22 is formed during the manufacturing process by preventing the flowable glass paste 22A from overflowing the recess edges 213 a of each groove 213. This prevents the second glaze layer 22 from spreading over the main surface 211 and is formed in a formation region defined by the recesses 212. Therefore, similar to the thermal printhead A40, the thermal printhead A41 can linearize each glaze edge 222 of the second glaze layer 22 and prevent the thickness of the second glaze layer 22 from becoming smaller due to spreading over the main surface 211.

[0076] Second Modification: Figure 26 is a diagram illustrating a thermal printhead A42 according to a second modification of the fourth embodiment. Figure 26 is an enlarged cross-sectional view of the thermal printhead A42, and corresponds to Figure 20. In this modification, the formation region of the second glaze layer 22 differs from that of the first modification described above.

[0077] In this modification, as in the first modification, the recess 212 is made up of two grooves 213 aligned in the sub-scanning direction y. Each groove 213 has a recess edge 213a and a recess edge 213b. The main surface 211 includes a groove land 211a located between the two grooves 213.

[0078] In this modification, the second glaze layer 22 is disposed on the land 211a of the main surface 211 as viewed in the thickness direction z, but is not disposed in the two grooves 213. In other words, the two grooves 213 are exposed from the second glaze layer 22. The glass paste 22A, which is the material of the second glaze layer 22, is fluid, but when disposed in the first glaze layer 21, surface tension prevents it from flowing beyond the recess edge 213b. Furthermore, the glass paste 22A becomes fluid when heated during firing, but surface tension prevents it from flowing beyond the recess edge 213b. As viewed in the thickness direction z, the glaze edge 222 and the recess edge 213b are aligned. More specifically, the glaze edge 222 on the upstream side y1 in the sub-scanning direction y coincides with the recessed edge 213b of the groove 213 on the upstream side y1 in the sub-scanning direction y, and the glaze edge 222 on the downstream side y2 in the sub-scanning direction y coincides with the recessed edge 213b of the groove 213 on the downstream side y2 in the sub-scanning direction y. The second glaze layer 22 is formed such that its formation area is defined by the recessed edge 213b of each groove 213 in the recess 212.

[0079] According to this modification, the first glaze layer 21 has a recess 212 consisting of two grooves 213. Furthermore, the second glaze layer 22 is disposed only on the inter-groove portions 211 a of the main surface 211 as viewed in the thickness direction z. The second glaze layer 22 is formed during the manufacturing process by preventing the flowable glass paste 22A from crossing the recess edges 213 b of each groove 213. This prevents the second glaze layer 22 from spreading over the main surface 211 and forms the formation area defined by the recesses 212. Therefore, similar to the thermal printhead A40, the thermal printhead A42 can linearize each glaze edge 222 of the second glaze layer 22 and prevent the thickness of the second glaze layer 22 from becoming smaller due to spreading over the main surface 211.

[0080] The thermal printhead and manufacturing method thereof, and the thermal printer equipped with the thermal printhead according to the present disclosure are not limited to the above-described embodiments. The specific configurations of each part of the thermal printhead and thermal printer according to the present disclosure, and the specific processing of each step of the manufacturing method of the thermal printhead according to the present disclosure, can be freely designed in various ways. The present disclosure includes the embodiments described in the following appendices.

[0081] Supplementary Note 1. A thermal printhead (A10) comprising: a substrate (1) having a substrate main surface (11) facing a first side (z1) in a thickness direction (z); a first glaze layer (21) disposed on the substrate main surface and having a first glaze main surface (211) facing the first side; a strip-shaped second glaze layer (22) disposed in contact with the first glaze main surface and extending in a main scanning direction (x); and a resistor layer (4) including a plurality of heating elements (41) arranged along the main scanning direction, wherein the plurality of heating elements are disposed in the second glaze layer. Supplementary Note 2. The thermal printhead according to Supplementary Note 1, wherein the first glaze layer is disposed over the entire surface of the substrate main surface. Supplementary Note 3. A thermal printhead according to Appendix 1 or 2, wherein the second glaze layer has a second glaze main surface (221) facing the first side, and the first glaze main surface is flat compared to the second glaze main surface. Appendix 4. A thermal printhead according to any of Appendixes 1 to 3, wherein a second softening point (T2) of the second glaze layer is lower than the first softening point (T1) of the first glaze layer. Appendix 5, Second and Third Embodiments, Fig. 12, Fig. 19. A thermal printhead according to any of Appendixes 1 to 4, further comprising a strip-shaped third glaze layer (23) interposed between the second glaze layer and the plurality of heat generating elements and extending in the main scanning direction. Appendix 6, Second Embodiment, Fig. 12. A thermal printhead according to Appendix 5, wherein the second glaze layer includes a plurality of regions (22a, 22b, 22c) spaced apart from each other in the sub-scanning direction. Appendix 7. A thermal printhead according to Appendix 5 or 6, wherein a third softening point (T3) of the third glaze layer is lower than the second softening point of the second glaze layer. Appendix 7-1. A thermal printhead according to Appendix 5 or 6, wherein the third softening point of the third glaze layer is the same as (or approximately the same as) the second softening point of the second glaze layer. Appendix 8. A thermal printhead according to any of Appendixes 1 to 7, wherein the substrate includes a ceramic.Supplementary Note 9, Fourth Embodiment, Figure 20. The thermal printhead according to any one of Supplementary Notes 1 to 8, wherein the first glaze layer further comprises a recess (212) recessed from the first glaze main surface in the thickness direction, the recess having a recess edge (212a) that is a boundary with the first glaze main surface and extends in the main scanning direction, and a glaze edge (222) of the second glaze layer and the recess edge coincide with each other when viewed in the thickness direction. Supplementary Note 10, Fourth Embodiment, Figure 20. The thermal printhead according to Supplementary Note 9, wherein the recess is a single groove extending in the main scanning direction, and the second glaze layer is disposed inside the recess when viewed in the thickness direction. Supplementary Note 11, First Modification of Fourth Embodiment, Figure 25. A thermal printhead according to Appendix 9, wherein the recess includes two grooves (213) aligned in the sub-scanning direction, and the second glaze layer is disposed in a groove-interval portion (211a) that is a portion between the two grooves on the first glaze main surface, and in the two grooves, as viewed in the thickness direction. Appendix 12, Second Modification of Fourth Embodiment, Figure 26. A thermal printhead according to Appendix 9, wherein the recess includes two grooves aligned in the sub-scanning direction, and the second glaze layer is disposed in a groove-interval portion that is a portion between the two grooves on the first glaze main surface, as viewed in the thickness direction, and the two grooves are exposed from the second glaze layer. Appendix 13, Figure 22. A thermal printhead according to any one of Appendixes 9 to 12, wherein the recess has a bottom surface (212c) facing a first side in the thickness direction, and the bottom surface is uneven. Appendix 14, Figure 2. A thermal printer (B1) comprising: a thermal printhead according to any one of Supplementary Notes 1 to 13; and a platen roller (81) disposed opposite the plurality of heat generating portions.Appendix 15, Figure 6. A method for manufacturing a thermal printhead, comprising: a substrate preparation step (S10) of preparing a substrate (1) having a substrate main surface (11) facing a first side (z1) in the thickness direction (z); a first arrangement step (S21) of arranging a first glaze material on the substrate main surface; and a second arrangement step (S23) of arranging a strip-shaped second glaze material (22A) extending in the main scanning direction (x) on the first glaze material using a dispenser. Appendix 16. A method for manufacturing a thermal printhead according to Appendix 15, further comprising: a first baking step (S22) of baking the first glaze material after the first arrangement step and before the second arrangement step; and a second baking step (S24) of baking the second glaze material after the second arrangement step. Appendix 17, Second embodiment, Figure 13. The method for manufacturing a thermal printhead according to Appendix 16, wherein the second glaze material arranged in the second arrangement step includes a plurality of regions (22A) spaced apart from each other in the sub-scanning direction (y), and further comprising a third arrangement step (S25) of arranging a band-shaped third glaze material (23A) extending in the main scanning direction so as to cover the second glaze material after the second arrangement step. Appendix 18, Second embodiment, FIG. 13. The method for manufacturing a thermal printhead according to Appendix 17, wherein the third arrangement step is performed after the second baking step, and further comprising a third baking step (S26) of baking the third glaze material after the third arrangement step. Appendix 19, Second embodiment, FIG. 18. The method for manufacturing a thermal printhead according to Appendix 17, wherein the second baking step is performed after the third arrangement step, and bakes the second glaze material and the third glaze material. Appendix 20, Fourth embodiment, FIG. 21. The method for manufacturing a thermal printhead according to any one of Supplementary Notes 16 to 19, further comprising a recess forming step (S27) of forming a recess that is recessed in the thickness direction from the first glaze main surface formed by firing the first glaze material and extends in the main scanning direction, after the first firing step and before the second disposing step.Supplementary Note 21, Fourth Embodiment, Figure 23.The method for manufacturing a thermal printhead according to Supplementary Note 20, wherein in the second disposing step, the second glaze material is disposed in the recess.Appendix 22. The method for manufacturing a thermal printhead according to Appendix 20, wherein the recess includes two grooves aligned in the sub-scanning direction, and the second disposing step disposes the second glaze material in a land portion that is a portion between the two grooves in the first glaze main surface as viewed in the thickness direction, and in the two grooves. Appendix 23. The method for manufacturing a thermal printhead according to Appendix 20, wherein the recess includes two grooves aligned in the sub-scanning direction, and the second disposing step disposes the second glaze material only in the land portion that is a portion between the two grooves in the first glaze main surface as viewed in the thickness direction. Appendix 24, Fourth embodiment, Figure 22. The method for manufacturing a thermal printhead according to any of Appendixes 20 to 23, wherein the recess is formed by wet blasting in the recess forming step. Appendix 25. The method for manufacturing a thermal printhead according to any of Appendixes 15 to 24, wherein the first glaze material is disposed over the entire surface of the substrate main surface.

[0082] A10, A20, A30, A40, A41, A42: thermal printhead 1: substrate 11: main surface 12: back surface 2: glaze layer 21: first glaze layer 211: main surface 211a: groove portion 212: recess 212a: recess edge 212b: side surface 212c: bottom surface 213: groove 213a, 213b: recess edge 22: second glaze layer 221: main surface 222: glaze edge 22a, 22b, 22c: region 23: third glaze layer 231: main surface 24: die bonding glaze 3: electrode layer 33: common electrode 34: common electrode strip portion 35: connecting portion 351: Ag layer 36: individual electrode 37: connecting portion 371: parallel portion 372: Oblique portion 38: Individual electrode strip portion 39: Bonding portion 39A: First bonding portion 39B: Second bonding portion 4: Resistor layer 41: Heat generating portion 5: Protective layer 71: Driver IC 72: Sealing resin 73: Wire 74: Connector 75: Heat dissipation member 81: Platen roller 82: Printing medium B1: Thermal printer 22A, 23A: Glass paste 99: Mask layer 99a: Opening

Claims

1. a substrate having a substrate main surface facing a first side in a thickness direction; a first glaze layer disposed on the substrate major surface and having a first glaze major surface facing the first side; a strip-shaped second glaze layer disposed in contact with the first glaze main surface and extending in a main scanning direction; a resistor layer including a plurality of heat generating portions arranged along the main scanning direction; Equipped with The plurality of heat generating portions are disposed in the second glaze layer. Thermal print head.

2. The first glaze layer is disposed on the entire main surface of the substrate.

2. The thermal printhead of claim 1.

3. The second glaze layer has a second glaze major surface facing the first side, The first glaze main surface is flat compared to the second glaze main surface; 2. The thermal printhead of claim 1.

4. The second softening point of the second glaze layer is lower than the first softening point of the first glaze layer.

2. The thermal printhead of claim 1.

5. The ink jet head further includes a belt-shaped third glaze layer interposed between the second glaze layer and the plurality of heat generating portions and extending in the main scanning direction.

2. The thermal printhead of claim 1.

6. The thermal printhead according to claim 5 , wherein the second glaze layer includes a plurality of regions spaced apart from one another in the sub-scanning direction.

7. The third softening point of the third glaze layer is lower than the second softening point of the second glaze layer.

6. The thermal printhead according to claim 5.

8. The substrate includes a ceramic.

2. The thermal printhead of claim 1.

9. The first glaze layer further includes a recess recessed in the thickness direction from the first glaze main surface, The recess has a recess edge that is a boundary with the first glaze main surface and extends in the main scanning direction, When viewed in the thickness direction, the glaze edge of the second glaze layer and the recess edge are aligned.

2. The thermal printhead of claim 1.

10. the recess is a groove extending in the main scanning direction, The second glaze layer is disposed on the inside of the recess when viewed in the thickness direction.

10. The thermal printhead of claim 9.

11. The recess includes two grooves aligned in the sub-scanning direction, The second glaze layer is disposed in a groove portion between the two grooves on the first glaze main surface and in the two grooves when viewed in the thickness direction.

10. The thermal printhead of claim 9.

12. The recess includes two grooves aligned in the sub-scanning direction, The second glaze layer is disposed in a groove portion between the two grooves on the first glaze main surface when viewed in the thickness direction, The two grooves are exposed from the second glaze layer.

10. The thermal printhead of claim 9.

13. The recess has a bottom surface facing a first side in the thickness direction, The bottom surface has projections and recesses.

10. The thermal printhead of claim 9.

14. A thermal printhead according to any one of claims 1 to 13, a platen roller disposed opposite the plurality of heat generating portions; Equipped with Thermal printer.

15. a substrate preparation step of preparing a substrate having a substrate main surface facing a first side in a thickness direction; a first disposing step of disposing a first glaze material on the main surface of the substrate; a second disposing step of disposing a strip-shaped second glaze material extending in a main scanning direction on the first glaze material by a dispenser; Equipped with A method for manufacturing a thermal printhead.

16. A first firing step of firing the first glaze material after the first arrangement step and before the second arrangement step; After the second arrangement step, a second firing step of firing the second glaze material; Further comprising: The method for manufacturing the thermal printhead according to claim 15.

17. the second glaze material arranged in the second arrangement step includes a plurality of regions spaced apart from each other in a sub-scanning direction, The method further includes a third arrangement step of arranging a band-shaped third glaze material extending in the main scanning direction so as to cover the second glaze material after the second arrangement step. The method for manufacturing the thermal printhead according to claim 16.

18. The third arrangement step is performed after the second firing step, After the third arrangement step, a third firing step of firing the third glaze material is further provided. The method for manufacturing the thermal printhead according to claim 17.

19. The second firing step is performed after the third arrangement step, and fires the second glaze material and the third glaze material. The method for manufacturing the thermal printhead according to claim 17.

20. The method further includes, after the first firing step and before the second disposing step, a recess forming step of forming a recess recessed in the thickness direction from a first glaze main surface formed by firing the first glaze material and extending in the main scanning direction, A method for manufacturing a thermal printhead according to any one of claims 16 to 19.

21. In the second disposing step, the second glaze material is disposed in the recess. The method for manufacturing a thermal printhead according to claim 20.

22. The recess includes two grooves aligned in the sub-scanning direction, In the second arrangement step, the second glaze material is arranged in a groove portion between the two grooves on the first glaze main surface and in the two grooves when viewed in the thickness direction. The method for manufacturing a thermal printhead according to claim 20.

23. The recess includes two grooves aligned in the sub-scanning direction, In the second disposing step, the second glaze material is disposed only in a groove portion between the two grooves on the first glaze main surface when viewed in the thickness direction. The method for manufacturing a thermal printhead according to claim 20.

24. In the recess forming step, the recess is formed by wet blasting. The method for manufacturing a thermal printhead according to claim 20.

25. The first glaze material is disposed over the entire main surface of the substrate; The method for manufacturing the thermal printhead according to claim 15.