Thermal printhead, thermal printer, and method for manufacturing thermal printhead

Abstract

This thermal print head comprises a substrate, a resistor layer, and a wiring layer. The substrate is composed of a crystal semiconductor and has a principal surface facing the thickness direction. The resistor layer is supported on the substrate and has a plurality of heat generating parts arranged in a principal scanning direction. The wiring layer is supported on the substrate and constitutes a current-carrying path to the plurality of heat generating parts. The wiring layer includes, for each of the plurality of heat generating parts: an electroconductive part having a resistance value per unit length in a sub scanning direction that is lower than the heat generating parts; and a sub heat generating part having a resistance value per unit length in the sub scanning direction that is a value between the resistance values of the heat generating parts and the electroconductive parts. The substrate has a protrusion which protrudes from the principal surface and extends in the principal scanning direction. The heat generating parts, the sub heat generating part, and the electroconductive part are formed on the protrusion. The sub heat generating part is sandwiched between the heat generating part and the electroconductive part in the sub scanning direction.

Description

[Technical Field]

[0001] The present disclosure relates to a thermal printhead and a thermal printer, and also to a method of manufacturing a thermal printhead. [Background technology]

[0002] Patent Document 1 discloses an example of a conventional thermal printhead. The thermal printhead disclosed therein includes a main substrate on which a conductive layer and a resistor layer are formed, and a circuit board on which a driver IC is mounted. The resistor layer has multiple heat generating elements arranged in the main scanning direction. The conductive layer forms a current path for supplying electricity to the multiple heat generating elements.

[0003] In printing with a thermal printhead, the heat generating portion of the resistor layer generates heat when current is applied, and this heat is transferred to the print medium (such as thermal paper) to cause it to develop color, resulting in printing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-65021 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present disclosure is to provide a thermal printhead and a thermal printer that are more durable and reliable than conventional ones, and another object of the present disclosure is to provide a method for manufacturing such a thermal printhead. [Means for solving the problem]

[0006] A thermal printhead provided by a first aspect of the present disclosure includes a substrate made of a single-crystal semiconductor and having a main surface facing in one direction in the thickness direction; a resistor layer supported by the substrate and having a plurality of heat-generating elements arranged in the main scanning direction; and a wiring layer supported by the substrate and forming a current path to the plurality of heat-generating elements. The wiring layer includes, for each of the plurality of heat-generating elements, a conductive portion having a resistance value per unit length in the sub-scanning direction lower than that of the heat-generating element, and a sub-heat-generating element having a resistance value per unit length in the sub-scanning direction intermediate between that of the heat-generating element and the conductive portion. The substrate has a convex portion protruding from the main surface and extending in the main scanning direction. The heat-generating element, the sub-heat-generating element, and the conductive portion are formed on the convex portion. The sub-heat-generating element is sandwiched between the heat-generating element and the conductive portion in the sub-scanning direction.

[0007] A thermal printer provided by a second aspect of the present disclosure includes the thermal printhead provided by the first aspect and a platen facing the thermal printhead.

[0008] A third aspect of the present disclosure provides a method for manufacturing a thermal printhead, comprising: a substrate preparation step of preparing a substrate made of a single-crystal semiconductor; a substrate processing step of forming, on the substrate, a main surface facing one side in the thickness direction and a convex portion protruding from the main surface and extending in the main scanning direction; a resistor layer formation step of forming a resistor layer supported by the substrate and having a plurality of heat generating elements arranged in the main scanning direction; and a wiring layer formation step of forming a wiring layer supported by the substrate and constituting a current path to the plurality of heat generating elements. The wiring layer includes, for each of the plurality of heat generating elements, a conductive portion having a resistance value per unit length in the sub-scanning direction lower than that of the heat generating elements, and a sub-heat generating portion having a resistance value per unit length in the sub-scanning direction intermediate between that of the heat generating elements and the conductive portion. The heat generating elements, the sub-heat generating portion, and the conductive portion are formed on the convex portion, and the sub-heat generating portion is sandwiched between the heat generating elements and the conductive portion in the sub-scanning direction. [Effects of the Invention]

[0009] The configurations of the present disclosure enable the durability and reliability of thermal printheads (and thermal printers) to be improved, and the method of manufacturing a thermal printhead of the present disclosure enables the manufacture of a thermal printhead with excellent durability and reliability. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a plan view showing a thermal printhead according to a first embodiment. [Figure 2] 2 is a plan view of a main part in which a part of the plan view shown in FIG. 1 is enlarged. [Figure 3] 3 is an enlarged plan view of a main part obtained by enlarging a part of the plan view shown in FIG. 2. [Figure 4] 4 is a partially enlarged cross-sectional view of a thermal printer including a thermal printhead according to a first embodiment, taken along line IV-IV in FIG. 1. FIG. [Figure 5] FIG. 5 is a cross-sectional view of a main part in which a part of the cross-sectional view shown in FIG. 4 is enlarged. [Figure 6] FIG. 6 is an enlarged cross-sectional view of a main part obtained by enlarging a part of the cross-sectional view shown in FIG. 5. [Figure 7] 2 is a cross-sectional view of a main part illustrating one step of a method for manufacturing a thermal printhead according to the first embodiment. FIG. [Figure 8] 2 is a cross-sectional view of a main part illustrating one step of a method for manufacturing a thermal printhead according to the first embodiment. FIG. [Figure 9] 2 is a cross-sectional view of a main part illustrating one step of a method for manufacturing a thermal printhead according to the first embodiment. FIG. [Figure 10] 3 is an enlarged cross-sectional view of a main part illustrating one step of a method for manufacturing a thermal printhead according to the first embodiment. FIG. [Figure 11] 2 is a cross-sectional view of a main part illustrating one step of a method for manufacturing a thermal printhead according to the first embodiment. FIG. [Figure 12] 2 is a cross-sectional view of a main part illustrating one step of a method for manufacturing a thermal printhead according to the first embodiment. FIG. [Figure 13]2 is a cross-sectional view of a main part illustrating one step of a method for manufacturing a thermal printhead according to the first embodiment. FIG. [Figure 14] 2 is a cross-sectional view of a main part illustrating one step of a method for manufacturing a thermal printhead according to the first embodiment. FIG. [Figure 15] 2 is a cross-sectional view of a main part illustrating one step of a method for manufacturing a thermal printhead according to the first embodiment. FIG. [Figure 16] 3 is an enlarged cross-sectional view of a main part illustrating one step of a method for manufacturing a thermal printhead according to the first embodiment. FIG. [Figure 17] FIG. 10 is a partially enlarged cross-sectional view of a thermal printer equipped with a thermal printhead according to a second embodiment. [Figure 18] FIG. 18 is a cross-sectional view of a main part in which a part of the cross-sectional view shown in FIG. 17 is enlarged. [Figure 19] FIG. 10 is an enlarged plan view of a main part of a thermal printhead according to a second embodiment. [Figure 20] FIG. 20 is a cross-sectional view taken along line XX-XX in FIG. 19. [Figure 21] FIG. 11 is an enlarged cross-sectional view of a main part of a thermal printhead according to a modified example of the second embodiment. [Figure 22] FIG. 10 is a cross-sectional view of a main part of a thermal printhead according to a third embodiment. [Figure 23] FIG. 10 is an enlarged cross-sectional view of a main part of a thermal printhead according to a third embodiment. [Figure 24] FIG. 11 is a cross-sectional view of a main part of a thermal printhead according to a modified example of the third embodiment. [Figure 25] FIG. 11 is an enlarged cross-sectional view of a main part of a thermal printhead according to a modified example of the third embodiment. [Figure 26] FIG. 10 is an enlarged plan view of a main part of a thermal printhead according to a fourth embodiment. [Figure 27] FIG. 10 is an enlarged cross-sectional view of a main part of a thermal printhead according to a fourth embodiment. [Figure 28] FIG. 11 is an enlarged cross-sectional view of a main part of a thermal printhead according to a modified example of the fourth embodiment. [Figure 29] FIG. 11 is an enlarged cross-sectional view of a main part of a thermal printhead according to a modified example of the fourth embodiment. [Figure 30] FIG. 11 is an enlarged cross-sectional view of a main part of a thermal printhead according to a modified example of the fourth embodiment. [Figure 31] FIG. 10 is an enlarged cross-sectional view of a main part of a thermal printhead according to a fifth embodiment. [Figure 32] FIG. 10 is an enlarged plan view of a main part of a thermal printhead according to a fifth embodiment. [Figure 33] FIG. 13 is an enlarged plan view of a main part of a thermal printhead according to a modified example of the fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The following description will discuss embodiments of the present disclosure with reference to the accompanying drawings. In the following description, identical or similar components are designated by the same reference numerals, and redundant description will be omitted.

[0012] 1 to 6 show a thermal printhead A1 according to the first embodiment. The thermal printhead A1 includes a head substrate 1, an insulating layer 19, a protective layer 2, a wiring layer 3, a resistor layer 4, a connection substrate 5, multiple wires 61 and 62, multiple driver ICs 7, a protective resin 78, and a heat dissipation member 8. The thermal printhead A1 is incorporated into a thermal printer Pr (see FIG. 4) that prints on a print medium (not shown). The thermal printer Pr includes a thermal printhead A1 and a platen roller 91. The platen roller 91 faces the thermal printhead A1. The print medium is sandwiched between the thermal printhead A1 and the platen roller 91 and transported in the sub-scanning direction by the platen roller 91. Examples of such print media include thermal paper for creating barcode sheets and receipts. A flat rubber platen may be used instead of the platen roller 91. The platen includes a portion of a cylindrical rubber having a large radius of curvature and an arcuate cross section. In this disclosure, the term "platen" includes both the platen roller 91 and a flat platen.

[0013] FIG. 1 is a plan view of a thermal printhead A1. FIG. 2 is a plan view of a main portion of the thermal printhead A1. FIG. 3 is an enlarged plan view of a main portion of the thermal printhead A1. FIG. 4 is an enlarged cross-sectional view of a portion of a thermal printer Pr equipped with the thermal printhead A1, corresponding to the cross-section taken along line IV-IV in FIG. 1. FIG. 5 is a cross-sectional view of a main portion of the thermal printhead A1. FIG. 6 is an enlarged cross-sectional view of a main portion of the thermal printhead A1. The protective layer 2 is omitted in FIGS. 1 to 3. The protective resin 78 is omitted in FIGS. 1 and 2. The multiple wires 61 are omitted in FIG. 2. In FIGS. 1 to 3, the lower side in the sub-scanning direction y is the upstream side, and the upper side is the downstream side. In FIGS. 4 to 6, the right side in the sub-scanning direction y is the upstream side, and the left side is the downstream side.

[0014] The head substrate 1 supports the wiring layer 3 and the resistor layer 4. The head substrate 1 has an elongated rectangular shape with the main scanning direction x as its longitudinal direction. In the following description, the thickness direction of the head substrate 1 is referred to as the thickness direction z. There are no particular limitations on the size of the head substrate 1, but as an example, the thickness (thickness direction z dimension) is 725 μm, the main scanning direction x dimension is 50 mm to 150 mm, and the sub-scanning direction y dimension is 2.0 mm to 5.0 mm.

[0015] The head substrate 1 is made of a single crystal semiconductor, such as silicon (Si). As shown in FIGS. 4 and 5, the head substrate 1 has a first main surface 11 and a first back surface 12. The first main surface 11 and the first back surface 12 are spaced apart in the thickness direction z and face opposite sides in the thickness direction z. The wiring layer 3 and the resistor layer 4 are provided on the side of the first main surface 11. The head substrate 1 is an example of a "substrate," and the first main surface 11 is an example of a "main surface."

[0016] The head substrate 1 has protrusions 13. The protrusions 13 protrude from the first main surface 11 in the thickness direction z and extend long in the main scanning direction x. In the example shown, the protrusions 13 are formed downstream in the sub-scanning direction y of the head substrate 1. The protrusions 13 are part of the head substrate 1 and are therefore made of Si, a single-crystal semiconductor.

[0017] The protrusion 13 has an apex 130, a pair of first inclined portions 131A and 131B, and a pair of second inclined portions 132A and 132B.

[0018] The apex 130 is the part of the protrusion 13 that is farthest from the first main surface 11. The apex 130 is, for example, a flat surface that is approximately parallel to the first main surface 11. When viewed in the thickness direction z, the apex 130 has an elongated rectangular shape that extends long in the main scanning direction x.

[0019] As shown in FIG. 6, the pair of first inclined portions 131A, 131B are connected to both sides of the apex 130 in the sub-scanning direction y. The first inclined portion 131A is connected to the apex 130 from the upstream side in the sub-scanning direction y. The first inclined portion 131B is connected to the apex 130 from the downstream side in the sub-scanning direction y. The first inclined portion 131A is an example of an "upstream first inclined portion," and the first inclined portion 131B is an example of a "downstream first inclined portion." Each of the pair of first inclined portions 131A, 131B is inclined by an angle α1 with respect to the first main surface 11 (inclined at the first inclination angle α1). Each of the pair of first inclined portions 131A, 131B is an elongated rectangular plane extending long in the main scanning direction x when viewed in the thickness direction z. The protrusion 13 may have inclined portions (not shown) that are connected to the pair of first inclined portions 131A and 131B and are adjacent to both ends of the apex 130 in the main scanning direction x.

[0020] As shown in FIG. 6 , the pair of second inclined portions 132A, 132B are connected to the pair of first inclined portions 131A, 131B on the side opposite the apex 130 in the sub-scanning direction y. The second inclined portion 132A is sandwiched between the first inclined portion 131A and the first main surface 11 in the sub-scanning direction y. The second inclined portion 132A is connected to the first inclined portion 131A from the upstream side in the sub-scanning direction y, and is connected to the first main surface 11 from the downstream side in the sub-scanning direction y. The second inclined portion 132B is sandwiched between the first inclined portion 131B and the first main surface 11 in the sub-scanning direction y. The second inclined portion 132B is connected to the first inclined portion 131B from the downstream side in the sub-scanning direction y, and is connected to the first main surface 11 from the upstream side in the sub-scanning direction y. The second inclined portion 132A is an example of an "upstream second inclined portion," and the second inclined portion 132B is an example of a "downstream second inclined portion." Each of the pair of second inclined portions 132A, 132B is inclined at an angle α2 with respect to the first main surface 11 (inclined at a second inclination angle α2). The angle α2 is greater than the angle α1. Each of the pair of second inclined portions 132A, 132B is an elongated rectangular plane extending long in the main scanning direction x when viewed in the thickness direction z. Each of the pair of second inclined portions 132A, 132B is connected to the first main surface 11. The protrusion 13 may have inclined portions (not shown) connected to the pair of second inclined portions 132A, 132B and positioned outward in the main scanning direction x at both ends of the apex 130 in the main scanning direction x.

[0021] In the head substrate 1, the first main surface 11 is a (100) plane (according to Miller indices). According to a manufacturing method example described below, the angle α1 (see FIG. 6) of each of the first inclined portions 131A, 131B with respect to the first main surface 11 is, for example, 30.1 degrees, and the angle α2 (see FIG. 6) of each of the second inclined portions 132A, 132B with respect to the first main surface 11 is, for example, 54.7 degrees. The dimension z of the protrusion 13 in the thickness direction is, for example, 150 μm or more and 300 μm or less.

[0022] As shown in FIGS. 5 and 6, the insulating layer 19 covers the first main surface 11 and the protrusions 13. The insulating layer 19 is intended to insulate the first main surface 11 side of the head substrate 1 more reliably. The insulating layer 19 is made of an insulating material. For example, SiO2 (TEOS-SiO2) formed as a film using TEOS (tetraethyl orthosilicate) as a raw material gas is used as the insulating material. Instead of TEOS-SiO2, for example, SiO2 formed by other methods or SiN may be used. The thickness of the insulating layer 19 is not particularly limited, but an example is 5 μm to 15 μm (preferably 5 μm to 10 μm).

[0023] The resistor layer 4 is supported by the head substrate 1, and in this embodiment, as shown in FIGS. 5 and 6, it is supported by the head substrate 1 via an insulating layer 19. The resistor layer 4 has a plurality of heat generating portions 41. The plurality of heat generating portions 41 are selectively energized to locally heat the print medium. Each heat generating portion 41 is an area of the resistor layer 4 that is exposed from the wiring layer 3. The plurality of heat generating portions 41 are arranged along the main scanning direction x and are spaced apart from each other in the main scanning direction x. The shape of each heat generating portion 41 is not particularly limited, and may be, for example, a rectangle with the sub-scanning direction y as the longitudinal direction when viewed from the thickness direction z. The resistor layer 4 is made of a material with a higher resistance than the wiring layer 3. Preferably, the electrical resistivity of the resistor layer 4 is 10 -6The resistivity is Ωm or more. For example, TaN is used as the constituent material of the resistor layer 4, but TaSiO2, TiON, PolySi, Ta2O5, RuO2, RuTiO, TaSiN, etc. may be used instead of TaN. The method for forming the resistor layer 4 is not particularly limited, but it can be formed by, for example, a sputtering method, a CVD method, plating, etc., and is appropriately selected depending on the constituent material used. For example, when the constituent material of the resistor layer 4 is TaN, the resistor layer 4 is formed by a sputtering method. The thickness of the resistor layer 4 is not particularly limited, but an example is 0.02 μm or more and 0.1 μm or less (preferably about 0.08 μm).

[0024] 6, each heat generating portion 41 is formed spanning from the first inclined portion 131B to the apex 130. The upstream end of each heat generating portion 41 in the sub-scanning direction y is located on the apex 130, and the downstream end of each heat generating portion 41 in the sub-scanning direction y is located on the first inclined portion 131B. The dimension in the sub-scanning direction y of the portion of each heat generating portion 41 formed on the apex 130 is, for example, approximately 10% to 30% of the dimension in the sub-scanning direction y of the entire heat generating portion 41.

[0025] The wiring layer 3 forms a current path for supplying current to the plurality of heat generating portions 41. The wiring layer 3 is supported by the head substrate 1, and in this embodiment, is laminated on the resistor layer 4 as shown in FIGS.

[0026] The wiring layer 3 has a plurality of individual electrodes 31 and a common electrode 32, as shown in FIGS.

[0027] As shown in Figures 2, 3, and 6, each of the multiple individual electrodes 31 is in the shape of a strip extending generally in the sub-scanning direction y. The multiple individual electrodes 31 are arranged upstream in the sub-scanning direction y with respect to the multiple heat generating portions 41. The downstream end of each individual electrode 31 in the sub-scanning direction y is arranged at a position overlapping with the peak 130 of the protrusion 13 on the upstream side in the sub-scanning direction y. As shown in Figures 2 and 5, each individual electrode 31 has an individual pad 311. The individual pad 311 is a portion to which a wire 61 is connected to establish electrical continuity with the driver IC 7.

[0028] As shown in FIGS. 2, 3, 5, and 6, the common electrode 32 has a connecting portion 323 and multiple strip portions 324. Each of the multiple strip portions 324 is located downstream of a corresponding heat generating portion 41 in the sub-scanning direction y. The upstream end of each strip portion 324 in the sub-scanning direction y faces the downstream end of each individual electrode 31 in the sub-scanning direction y, with each heat generating portion 41 sandwiched between them. The upstream end of each strip portion 324 in the sub-scanning direction y is located at a position overlapping the first inclined portion 131B of the protrusion 13. The connecting portion 323 is located downstream of the multiple strip portions 324 in the sub-scanning direction y, and connects the multiple strip portions 324. The connecting portion 323 extends in the main scanning direction x and is a relatively wide portion whose dimension in the sub-scanning direction y is greater than the dimension in the main scanning direction x of each strip portion 324. 1, the connecting portion 323 extends from the downstream side in the sub-scanning direction y of the plurality of heat generating portions 41 to the upstream side in the sub-scanning direction y, bypassing both sides in the main scanning direction x. In this embodiment, of the common electrode 32, the downstream portions in the sub-scanning direction y of the plurality of strip-shaped portions 324 and the connecting portion 323 are formed on the first main surface 11 of the head substrate 1 (in other words, above the first main surface 11).

[0029] The wiring layer 3 (plurality of individual electrodes 31 and common electrode 32) is configured to include a first conductor layer 301 and a second conductor layer 302 stacked in the thickness direction z.

[0030] The first conductor layer 301 is formed on the resistor layer 4. The first conductor layer 301 is made of a material having a lower resistance than the resistor layer 4 and a higher resistance than the second conductor layer 302. Preferably, the electrical conductivity of the first conductor layer 301 is, for example, 10 -6 ~10 -7The thermal conductivity of the first conductor layer 301 is preferably less than 100 W / m. The first conductor layer 301 is made of titanium (Ti), for example. However, Ta, Ga, Sn, PtIr, Pt, thallium (Ti), vanadium (V), or Cr may be used instead of Ti. The method for forming the first conductor layer 301 is not particularly limited, but may be formed by sputtering, CVD, plating, or the like, and is appropriately selected depending on the material used. For example, when the first conductor layer 301 is made of Ti, the first conductor layer 301 is formed by sputtering. The thickness of the first conductor layer 301 is not particularly limited, but an example is 0.1 μm or more and 0.2 μm or less.

[0031] The second conductor layer 302 is formed on the first conductor layer 301. The second conductor layer 302 partially covers the first conductor layer 301. Therefore, the first conductor layer 301 has a portion exposed from the second conductor layer 302. The second conductor layer 302 is made of a material having a lower resistance than the resistor layer 4 and the first conductor layer 301. Preferably, the electrical resistivity of the second conductor layer 302 is, for example, 10 -7The thermal conductivity of the second conductor layer 302 is Ω / m or less. The second conductor layer 302 is made of a material having a higher thermal conductivity than the first conductor layer 301. Preferably, the thermal conductivity of the second conductor layer 302 is, for example, 100 W / m or more. The second conductor layer 302 is made of, for example, Cu. However, instead of Cu, a Cu alloy, Al, Al alloy, Au, Ag, Ni, or W (tungsten) may be used. The method for forming the second conductor layer 302 is not particularly limited, and may be, for example, sputtering, CVD, plating, or the like, and is appropriately selected depending on the constituent material used. For example, when the second conductor layer 302 is made of Cu, the second conductor layer 302 is formed by sputtering. When the second conductor layer 302 is made of Au, Ag, or Ni, it is generally formed by plating. In this case, the second conductor layer 302 may include a seed layer (for example, Cu). The second conductor layer 302 is thicker than the first conductor layer 301. The thickness of the second conductor layer 302 depends on the material used, the value of the current flowing through the wiring layer 3, etc. An example of the thickness of the second conductor layer 302 is 0.5 μm or more and 5 μm or less.

[0032] The wiring layer 3 has a pair of sub-heat generating portions 35A, 35B and a pair of conductive portions 36A, 36B for each of the plurality of heat generating portions 41.

[0033] The pair of sub-heating portions 35A, 35B are formed by portions of the first conductor layer 301 that are exposed from the second conductor layer 302. In other words, the pair of sub-heating portions 35A, 35B are portions of the wiring layer 3 where the second conductor layer 302 is not stacked on the first conductor layer 301. The pair of sub-heating portions 35A, 35B are adjacent to both ends of each heat-generating portion 41 in the sub-scanning direction y. The sub-heating portion 35A is adjacent to each heat-generating portion 41 from the upstream side in the sub-scanning direction y, and the sub-heating portion 35B is adjacent to each heat-generating portion 41 from the downstream side in the sub-scanning direction y. The sub-heating portion 35A is an example of an "upstream sub-heating portion," and the sub-heating portion 35B is an example of a "downstream sub-heating portion."

[0034] The sub-heating portion 35A is formed on the apex 130. Both ends of the sub-heating portion 35A in the sub-scanning direction y are located on the apex 130. The sub-heating portion 35B is formed spanning from the first inclined portion 131B to the second inclined portion 132B. The upstream end of the sub-heating portion 35B in the sub-scanning direction y is located on the first inclined portion 131B, and the downstream end of the sub-heating portion 35B in the sub-scanning direction y is located on the second inclined portion 132B.

[0035] The pair of conductive portions 36A, 36B are composed of a first conductor layer 301 and a second conductor layer 302. In other words, the pair of conductive portions 36A, 36B are portions in which the second conductor layer 302 is stacked on the first conductor layer 301 in the wiring layer 3. The pair of conductive portions 36A, 36B are located on the opposite side of the pair of sub-heating portions 35A, 35B from the respective heat-generating portions 41 in the sub-scanning direction y. The conductive portion 36A is adjacent to the sub-heating portion 35A from the upstream side in the sub-scanning direction y, and the conductive portion 36B is adjacent to the sub-heating portion 35B from the downstream side in the sub-scanning direction y. The conductive portion 36A is an example of an "upstream conductive portion," and the conductive portion 36B is an example of a "downstream conductive portion."

[0036] The conductive portion 36A is formed from the apex 130, via the first inclined portion 131A and the second inclined portion 132A, across to the first main surface 11 on the upstream side in the sub-scanning direction y of the convex portion 13. The downstream end of the conductive portion 36A in the sub-scanning direction y is located on the apex 130. The conductive portion 36B is formed from the second inclined portion 132B, across to the first main surface 11 on the downstream side in the sub-scanning direction y of the convex portion 13. The upstream end of the conductive portion 36B in the sub-scanning direction y is located on the second inclined portion 132B.

[0037] Since the resistance values of the first conductor layer 301, the second conductor layer 302, and the resistor layer 4 satisfy the above-described relationship, the conductive portions 36A and 36B have a smaller resistance per unit length in the sub-scanning direction y than the heat generating portion 41. The sub-heat generating portions 35A and 35B have a resistance per unit length in the sub-scanning direction y that is between the heat generating portion 41 and the conductive portions 36A and 36B. Therefore, when a current is applied to each heat generating portion 41, the heat generation amount of each of the pair of sub-heat generating portions 35A and 35B is smaller than the heat generation amount of each of the heat generating portions 41, but larger than the heat generation amount of each of the pair of conductive portions 36A and 36B. For example, when a current is applied and each heat generating portion 41 reaches approximately 300°C, the pair of sub-heat generating portions 35A and 35B each reach approximately 150 to 200°C.

[0038] The protective layer 2 covers the wiring layer 3 and the resistor layer 4 and protects them. The protective layer 2 is made of an insulating material. For example, SiN (silicon nitride) is used as this insulating material, but SiO2 (silicon oxide), SiC (silicon carbide), AlN (aluminum nitride), etc. may be used instead of SiN. The protective layer 2 is composed of a single layer or multiple layers containing the insulating material described above. The thickness of the protective layer 2 is not particularly limited, but an example is 1.0 μm to 10 μm.

[0039] As shown in FIG. 5 , the protective layer 2 has a plurality of pad openings 21. Each pad opening 21 penetrates the protective layer 2 in the thickness direction z. Each of the plurality of pad openings 21 exposes an individual pad 311 of a corresponding individual electrode 31. Unlike the illustrated example, the plurality of pad openings 21 may be filled with a conductive material. In this case, a plating layer may be formed on this conductive material. The configuration of this plating layer is not particularly limited, but as an example, Ni, Pd (palladium), and Au are stacked in this order from the surface of the conductive material.

[0040] As shown in FIGS. 1 and 4, the connection board 5 is disposed upstream of the head substrate 1 in the sub-scanning direction y. The connection board 5 is, for example, a PCB board, and is equipped with a driver IC 7 and a connector 59 (described later). The shape of the connection board 5 is not particularly limited, but in this embodiment, it is rectangular with the main scanning direction x as its longitudinal direction. The connection board 5 has a second main surface 51 and a second back surface 52. The second main surface 51 faces the same side as the first main surface 11 of the head substrate 1, and the second back surface 52 faces the same side as the first back surface 12 of the head substrate 1. In this embodiment, the second main surface 51 is positioned lower in the thickness direction z than the first main surface 11 in the drawing.

[0041] The driver IC 7 is mounted on the second main surface 51 of the connection board 5 and serves to individually energize the plurality of heat generating elements 41. The plurality of driver ICs 7 are connected to the plurality of individual electrodes 31 by a plurality of wires 61. The control of energization of the plurality of heat generating elements 41 by the plurality of driver ICs 7 is in accordance with a command signal input from outside the thermal printhead A1 via the connection board 5. The plurality of driver ICs 7 are connected to a wiring pattern (not shown) of the connection board 5 by a plurality of wires 62. The plurality of driver ICs 7 are provided as appropriate according to the number of the plurality of heat generating elements 41.

[0042] The driver ICs 7, wires 61, and wires 62 are covered with protective resin 78. The protective resin 78 is made of, for example, insulating resin and is, for example, black. The protective resin 78 is formed so as to straddle the head substrate 1 and the connection substrate 5.

[0043] The connector 59 is used to connect the thermal printhead A1 to the thermal printer Pr. The connector 59 is attached to the connection board 5 and connected to the wiring pattern (not shown) of the connection board 5.

[0044] The heat dissipation member 8 supports the head substrate 1 and the connection substrate 5, and dissipates some of the heat generated by the multiple heat generating portions 41 to the outside via the head substrate 1. The heat dissipation member 8 is a block-shaped member made of a metal such as Al. The heat dissipation member 8 has a first support surface 81 and a second support surface 82. The first support surface 81 and the second support surface 82 each face upward in the thickness direction z and are arranged side by side in the sub-scanning direction y. The first support surface 81 is joined to the first support surface 81. The second back surface 52 of the connection substrate 5 is joined to the second support surface 82.

[0045] Next, an example of a method for manufacturing the thermal printhead A1 will be described below with reference to FIGS.

[0046] First, as shown in FIG. 7, a substrate material 1K is prepared. The substrate material 1K is made of a single-crystal semiconductor and is, for example, a portion of a substantially circular Si wafer. One Si wafer contains multiple substrate materials 1K. In the following figures, one substrate material 1K (head substrate 1) that is a portion of the Si wafer and corresponds to one thermal printhead A1 may be illustrated. The thickness of the substrate material 1K (in other words, the thickness of the Si wafer) is not particularly limited, but in this embodiment, it is, for example, approximately 725 μm. The substrate material 1K has a first main surface 11K and a first back surface 12K facing opposite each other. The first main surface 11K is a (100) plane.

[0047] Next, the first main surface 11K is covered with a predetermined mask layer, and then anisotropic etching using, for example, KOH is performed. As a result, as shown in FIG. 8, a convex portion 13K is formed on the substrate material 1K. The convex portion 13K protrudes from the first main surface 11K and extends longitudinally in the main scanning direction x. The convex portion 13K has an apex 130K and a pair of inclined portions 132K. The apex 130K is a surface parallel to the first main surface 11K and is the same (100) plane as the first main surface 11K. The pair of inclined portions 132K are located on both sides of the apex 130K in the sub-scanning direction y and are interposed between the apex 130K and the first main surface 11K. Each of the pair of inclined portions 132K is a flat surface inclined relative to the apex 130K and the first main surface 11K. The angle formed by each of the pair of inclined portions 132K with the first main surface 11K and the top portion 130K is 54.7 degrees.

[0048] Next, after removing the mask layer, anisotropic etching is performed using, for example, KOH. As a result, the substrate material 1K becomes the head substrate 1 having a first main surface 11, a first back surface 12, and a convex portion 13, as shown in FIGS. 9 and 10. The convex portion 13 has an apex 130, a pair of first inclined portions 131A, 131B, and a pair of second inclined portions 132A, 132B. The apex 130 is the portion that was apex 130K, and the pair of second inclined portions 132A, 132B are the portions that were the pair of inclined portions 132K. The pair of first inclined portions 131A, 131B are the portions where the boundary between the apex 130K and the pair of inclined portions 132K is etched with KOH. The angle α1 (see FIG. 10) of each of the first inclined portions 131A, 131B relative to the first main surface 11 is 30.1 degrees, and the angle α2 (see FIG. 10) of each of the second inclined portions 132A, 132B relative to the first main surface 11 is 54.7 degrees. The process of forming the head substrate 1 from the above-mentioned substrate material 1K (see FIGS. 8 to 10) is an example of a "substrate processing process." In the substrate processing process, the first main surface 11 and the protrusions 13 are formed.

[0049] 11, an insulating layer 19 is formed. The insulating layer 19 is formed, for example, by using CVD to deposit SiO formed using TEOS (tetraethyl orthosilicate) as a raw material gas on the head substrate 1. The method for forming the insulating layer 19 is not limited to this, and other methods may also be used.

[0050] Next, the resistor film 4K is formed as shown in Fig. 12. In the step of forming the resistor film 4K (resistor film forming step), a thin film of TaN is formed on the insulating layer 19 by, for example, sputtering. The method of forming the resistor film 4K is not limited to this, and other methods may also be used.

[0051] Next, as shown in Figures 13 and 14, the wiring film 3K is formed. The process of forming the wiring film 3K includes two processes: forming a first conductor film 301K shown in Figure 13 and forming a second conductor film 302K shown in Figure 14. In the process of forming the first conductor film 301K (first film formation process), a thin film of Ti is formed on the resistor film 4K by, for example, sputtering. At this time, the first conductor film 301K covers substantially the entire surface of the resistor film 4K. In the process of forming the second conductor film 302K (second film formation process), a layer made of Cu is formed on the first conductor film 301K by, for example, plating or sputtering. At this time, the second conductor film 302K covers substantially the entire surface of the first conductor film 301K.

[0052] Next, as shown in FIGS. 15 and 16, the second conductor film 302K is partially removed, the first conductor film 301K is partially removed, and the resistor film 4K is partially removed. The process of partially removing the first conductor film 301K (first partial removal process), the process of partially removing the second conductor film 302K (second partial removal process), and the process of partially removing the resistor film 4K (resistor film partial removal process) are each performed by, for example, etching. The first partial removal process forms the first conductor layer 301, the second partial removal process forms the second conductor layer 302, and the resistor film partial removal process forms the resistor layer 4. Therefore, the process of forming the wiring layer 3 (wiring layer formation process) includes a first film formation process, a second film formation process, a first partial removal process, and a second partial removal process. Furthermore, the process of forming the resistor layer 4 (resistor layer formation process) includes a resistor film formation process and a resistor film partial removal process. The resistor film partial removal process may be performed before the first film formation process and the second film formation process. The formed first conductor layer 301 and second conductor layer 302 constitute the wiring layer 3, which has a plurality of individual electrodes 31 and a common electrode 32. The wiring layer 3 also has a plurality of sub-heat generating portions 35A, 35B and a plurality of conductive portions 36A, 36B. The formed resistor layer 4 has a plurality of heat generating portions 41.

[0053] Next, the protective layer 2 is formed. The protective layer 2 is formed by depositing SiN on the insulating layer 19, the wiring layer 3 (the first conductor layer 301 and the second conductor layer 302), and the resistor layer 4 using, for example, CVD. In addition, the protective layer 2 is partially removed by etching or the like to form pad openings 21. Thereafter, a dicing device or the like is used to separate the single Si wafer into a plurality of head substrates 1 (see FIGS. 1, 4, and 5).

[0054] After that, an assembly process is carried out for one head substrate 1. The above-mentioned thermal printhead A1 is obtained through processes such as attaching the head substrate 1 and connection substrate 5 to the heat dissipation member 8, mounting the driver IC 7 on the connection substrate 5, bonding the multiple wires 61 and 62, and forming the protective resin 78.

[0055] The functions and effects of the above-described thermal printhead A1 are as follows.

[0056] In the thermal printhead A1, each sub-heating element 35A, 35B is sandwiched between the corresponding heat-generating element 41 and the corresponding conductive element 36A, 36B in the sub-scanning direction y. When power is applied, the sub-heating elements 35A, 35B have a lower temperature than the corresponding heat-generating element 41 but a higher temperature than the corresponding conductive element 36A, 36B. This reduces the temperature gradient in the sub-scanning direction y compared to when the heat-generating element 41 and the corresponding conductive element 36A, 36B are adjacent to each other. If the heat-generating element 41 and the corresponding conductive element 36A, 36B were adjacent to each other, thermal stress caused by the temperature difference between them could cause a break at the interface between them. In contrast, the thermal printhead A1 can suppress damage caused by thermal stress, thereby improving the durability and reliability of the thermal printhead A1. In particular, providing a pair of sub-heating portions 35A, 35B on both sides of each heat-generating portion 41 in the sub-scanning direction y is preferable for improving durability and reliability by mitigating the temperature gradient.

[0057] In the thermal printhead A1, a sub-heating element 35A is provided upstream of each heat-generating element 41 in the sub-scanning direction y. As a result, the print medium fed in the sub-scanning direction y is first heated by the sub-heating element 35A and then by each heat-generating element 41, which has a higher temperature. The sub-heating element 35A generates heat at a higher temperature than the conductive element 36A, but its temperature is approximately 150 to 200°C under energization conditions that heat each heat-generating element 41 to approximately 300°C. Given this temperature and the short time it takes for the print medium to pass the sub-heating element 35A from upstream in the sub-scanning direction y, a print medium such as thermal paper with typical sensitivity does not develop a clear color when heated by the sub-heating element 35A. However, when heated by each heat-generating element 41, the color develops more quickly and clearly due to the preheating by the sub-heating element 35A. This improves print quality and printing speed. Furthermore, compared to a printer without the sub-heating element 35A, it is possible to color the print medium even when the temperature of each heat-generating element 41 is lowered. This improves energy efficiency and further alleviates the temperature gradient described above, contributing to reduced power consumption and improved durability and reliability. This means that the energy load is distributed to the sub-heating element 35A rather than concentrated on each heat-generating element 41, which helps prevent deterioration and degradation of each heat-generating element 41. Furthermore, since the temperature gradient described above can be alleviated, it contributes to improved durability and reliability without reducing printing efficiency. The thermal printhead A1 is capable of saving energy and having a long life.

[0058] In the thermal printhead A1, the first conductor layer 301 is made of a material with lower thermal conductivity than the second conductor layer 302. This allows the sub-heating unit 35A to block the heat generated in the heat-generating unit 41 from being released toward the conductive unit 36A. This prevents the heat generated in the heat-generating unit 41 from being wasted, thereby improving energy efficiency and heat generation responsiveness.

[0059] In the thermal printhead A1, the protrusion 13 has a peak 130, a pair of first inclined portions 131A and 131B, and a pair of second inclined portions 132A and 132B. The pair of first inclined portions 131A and 131B and the pair of second inclined portions 132A and 132B are aligned in the sub-scanning direction y, sandwiching the peak 130 therebetween. Thus, the protrusion 13 is configured with a two-stage inclination relative to the peak 130 (first main surface 11). This allows for a small angle α1 between the peak 130 and each of the first inclined portions 131A and 131B, which is favorable for improving print quality. Furthermore, the smaller the angle α1 between the peak 130 and each of the first inclined portions 131A and 131B, the more effectively the protective layer 2 is prevented from wearing down due to the passage of the print medium during printing. This enables improved print quality and a longer life for the thermal printhead A1.

[0060] In the thermal printhead A1, each heat generating element 41 is formed on the first inclined portion 131B. This allows good print quality to be obtained even when the contact center 910 (see FIG. 4) of the platen roller 91 with each heat generating element 41 is shifted downstream in the sub-scanning direction y relative to the convex portion 13. This arrangement is advantageous for avoiding interference between the platen roller 91 and the protective resin 78, and allows the head substrate 1 to be reduced in size in the sub-scanning direction y.

[0061] In the thermal printhead A1, each heat generating portion 41 is formed across from the first inclined portion 131B to the apex 130. This makes it possible to suppress a decrease in print quality even if the platen roller 91 is misaligned in the sub-scanning direction y.

[0062] In the thermal printhead A1, the sub-heating unit 35A is formed on the top 130, but not on the first inclined portion 131A. In a configuration different from the thermal printhead A1, for example, the sub-heating unit 35A is formed straddling the top 130 and the first inclined portion 131A to account for misalignment of the platen roller 91 in the sub-scanning direction y. However, due to improved manufacturing precision, even if the platen roller 91 is misaligned in the sub-scanning direction y, the contact center 910 is unlikely to shift upstream of the top 130 in the sub-scanning direction y. Furthermore, the sub-heating unit 35A does not significantly contribute to printing, and the larger the sub-heating unit 35A, the greater the energy loss. For these reasons, the thermal printhead A1 can reduce energy loss and suppress a decrease in printing efficiency due to energy loss compared to when the sub-heating unit 35A is formed straddling the top 130 and the first inclined portion 131A. That is, the thermal printhead A1 can mitigate the temperature gradient by providing the sub-heating portion 35A, and can also suppress a decrease in printing efficiency due to energy loss by adjusting the size (formation area) of the sub-heating portion 35A.

[0063] In the thermal printhead A1, the common electrode 32 is located downstream in the sub-scanning direction y from the heat generating elements 41, so that only the individual electrodes 31 are arranged upstream in the sub-scanning direction y from the heat generating elements 41. This makes it possible to reduce the arrangement pitch of the individual electrodes 31 in the main scanning direction x, thereby enabling higher-resolution printing.

[0064] In the thermal printhead A1, the first conductor layer 301 is made of, for example, Ti, and the second conductor layer 302 is made of, for example, Cu. This allows the resistance per unit length in the sub-scanning direction y of the portions of the first conductor layer 301 exposed from the second conductor layer 302, i.e., the sub-heating portions 35A and 35B, to be greater than the resistance per unit length in the sub-scanning direction y of the portions where the first conductor layer 301 and the second conductor layer 302 are stacked, i.e., the conductive portions 36A and 36B. Furthermore, because the first conductor layer 301 is thinner than the second conductor layer 302, the cross-sectional area of each of the sub-heating portions 35A and 35B in the wiring layer 3 is smaller than the cross-sectional area of each of the conductive portions 36A and 36B. This allows the resistance value per unit length in the sub-scanning direction y of each of the sub-heating portions 35A, 35B to be greater than the resistance value per unit length in the sub-scanning direction y of each of the conductive portions 36A, 36B.

[0065] 17 to 20 show a thermal printhead B1 according to the second embodiment.

[0066] Fig. 17 is a partially enlarged cross-sectional view of a thermal printer Pr equipped with a thermal printhead B1, corresponding to the cross-sectional view of Fig. 4 in the first embodiment. Fig. 18 is a cross-sectional view of a main part of the thermal printhead B1, corresponding to the cross-sectional view of Fig. 5 in the first embodiment. Fig. 19 is an enlarged plan view of a main part of the thermal printhead B1. Fig. 20 is an enlarged cross-sectional view of a main part taken along line XX-XX in Fig. 19.

[0067] In the thermal printhead B1, the convex portions 13 are formed so as to contact the downstream end in the sub-scanning direction y of the head substrate 1. In other words, the first main surface 11 does not exist in the region downstream in the sub-scanning direction y of the convex portions 13. Therefore, in the wiring layer 3 of this embodiment, as shown in FIG. 20 , the downstream end in the sub-scanning direction y of the conductive portion 36B overlaps the second inclined portion 132B.

[0068] The wiring layer 3 of this embodiment has a plurality of individual electrodes 31, a plurality of common electrodes 32, and a plurality of relay electrodes 33, as shown in FIG.

[0069] As shown in FIG. 19 , the individual electrodes 31 and the common electrodes 32 are arranged upstream of the heat generating portions 41 in the sub-scanning direction y. The relay electrodes 33 are arranged downstream of the heat generating portions 41 in the sub-scanning direction y. The individual electrodes 31 and the common electrodes 32 are arranged substantially parallel to each other at a predetermined pitch in the main scanning direction x. The relay electrodes 33 are arranged at a predetermined pitch in the main scanning direction x. Each relay electrode 33 is shaped to form a current path that turns back in the sub-scanning direction y. Each relay electrode 33 is formed across the first inclined portion 131B and the second inclined portion 132B of the convex portion 13.

[0070] As a representative of each common electrode 32, the left common electrode 32 of the two common electrodes 32 designated by the reference symbol "32(3)" in FIG. 19 will be described as an example. As shown in FIG. 19, the common electrode 32 has a branch portion 325 and two adjacent strip portions 324. The two strip portions 324 are located at the downstream end of each common electrode 32 in the sub-scanning direction y. The branch portion 325 is provided on the downstream side of each common electrode 32 in the sub-scanning direction y and is connected to the two strip portions 324. The branch portion 325 is connected to two adjacent heat generating portions 41 (the fourth and fifth from the left in FIG. 19) from the upstream side in the sub-scanning direction y via the two strip portions 324. Portions of two adjacent relay electrodes 33 (respective inner portions of each relay electrode 33) are connected to these two heat generating portions 41 from the downstream side in the sub-scanning direction y. The other portions of these two relay electrodes 33 (the outer portions of each relay electrode 33) are further connected to two heat generating portions 41 (the third and sixth from the left in FIG. 19) from the downstream side in the sub-scanning direction y. That is, a total of two heat generating portions 41 (the third and sixth from the left) are arranged on the outer side in the main scanning direction x (the left and right sides in FIG. 19) of two adjacent heat generating portions 41 (the fourth and fifth from the left) that are each connected to one common electrode 32. Two individual electrodes 31 (the two individual electrodes 31 located on both sides of the representative common electrode 32) are adjacent to each of these two heat generating portions 41 located on the outer side in the main scanning direction x of the two adjacent heat generating portions 41.

[0071] The above-described arrangement forms two adjacent current-carrying paths from one common electrode 32. Each of the two current-carrying paths includes, in order of connection, one common electrode 32, one branch portion 325, one of the two strip portions 324, one heat-generating portion 41, one relay electrode 33, another heat-generating portion 41 adjacent to the one heat-generating portion 41, and one individual electrode 31. By energizing one of the two individual electrodes 31, electricity is passed through two heat-generating portions 41 connected between that one individual electrode 31 and the common electrode 32 and adjacent to each other in the main scanning direction x, causing them to generate heat. These two adjacent heat-generating portions 41 correspond to one point (one dot) on the printing medium.

[0072] 17, the contact center 910 between the platen roller 91 and each heat generating element 41 is positioned downstream in the sub-scanning direction y with respect to the convex portions 13 of the head substrate 1. As a result, the platen roller 91 is pressed against the multiple heat generating elements 41 formed on the convex portions 13 via the protective layer 2, with the platen roller 91 in a position biased toward the downstream side in the sub-scanning direction y.

[0073] In the thermal printhead B1, as in the thermal printhead A1, each sub-heating element 35A, 35B is sandwiched between a heat-generating element 41 and a conductive element 36A, 36B. This makes it possible to reduce the temperature gradient in the sub-scanning direction y compared to when each heat-generating element 41 and each conductive element 36A, 36B are adjacent to each other. Therefore, as in the first embodiment, the durability and reliability of the thermal printhead B1 can be improved.

[0074] In the thermal printhead B1, the first main surface 11 does not exist in the area downstream of the protrusions 13 in the sub-scanning direction y. This configuration shortens the length of the head substrate 1 downstream in the sub-scanning direction y. As a result, when the print medium is transported, it is possible to prevent the print medium from coming into contact with the head substrate 1 downstream of the protrusions 13 in the sub-scanning direction y. This is preferable for a thermal printer Pr incorporating the thermal printhead B1 to have a straight path mechanism, as the print medium P1 can be transported without being curved or bent, as shown in FIG. 17. A thermal printer Pr with a straight path mechanism can use plastic cards with a thermosensitive layer as the print medium.

[0075] In the second embodiment, an example was shown in which the first main surface 11 is absent in the region downstream of the protrusions 13 in the sub-scanning direction y, but the present disclosure is not limited to this. For example, a very small portion of the first main surface 11 may be present downstream of the protrusions 13 in the sub-scanning direction y compared to the thermal printhead A1. FIG. 21 is an enlarged cross-sectional view of a main portion of a thermal printhead B2 according to this modification, corresponding to the cross-sectional view of FIG. 20. In the thermal printhead B2, the portion of the first main surface 11 downstream of the protrusions 13 in the sub-scanning direction y is very small. Therefore, similar to the thermal printhead B1, contact of the print medium with the head substrate 1 downstream of the protrusions 13 in the sub-scanning direction y during transport of the print medium can be prevented. In other words, similar to the thermal printhead B1, the thermal printhead B2 shown in FIG. 21 is also preferable for a straight-path mechanism.

[0076] Figures 22 and 23 show a thermal printhead C1 according to the third embodiment. Figure 22 is a cross-sectional view of the thermal printhead C1 and corresponds to Figure 5. Figure 23 is an enlarged cross-sectional view of the thermal printhead C1 and corresponds to Figure 6.

[0077] 22 and 23, the thermal printhead C1 differs from the thermal printhead A1 in the stacking order of the resistor layer 4 and the wiring layer 3. In the thermal printhead C1, the wiring layer 3 (first conductor layer 301 and second conductor layer 302) is stacked on the head substrate 1 (first main surface 11 and convex portions 13) with an insulating layer 19 interposed between them, and the resistor layer 4 is formed thereon.

[0078] In the manufacturing method of the thermal printhead C1, the resistor layer 4 is formed after the wiring layer 3 is formed. Specifically, in the manufacturing method of the thermal printhead A1, after the insulating layer 19 is formed (see FIG. 11), the resistor film forming step is not performed, and the first film forming step and the second film forming step are performed in this order. Next, the first partial removal step and the second partial removal step are performed. As a result, the wiring layer 3 (first conductor layer 301 and second conductor layer 302) is laminated on the insulating layer 19. In other words, the wiring layer forming step is performed before the resistor film forming step. Next, the resistor film forming step and the resistor film partial removal step are performed in this order. As a result, the resistor layer 4 is laminated on the wiring layer 3 and the insulating layer 19 exposed from the wiring layer 3. Thereafter, the processes from the formation of the protective layer 2 onwards are performed, as in the thermal printhead A1.

[0079] In the thermal printhead C1, as in the thermal printhead A1, each sub-heating element 35A, 35B is sandwiched between a heat-generating element 41 and a conductive element 36A, 36B. This makes it possible to reduce the temperature gradient in the sub-scanning direction y compared to when each heat-generating element 41 and each conductive element 36A, 36B are adjacent to each other. Therefore, as in the first embodiment, the durability and reliability of the thermal printhead C1 can be improved.

[0080] In the thermal printhead C1, the wiring layer 3 (first conductor layer 301 and second conductor layer 302) and the resistor layer 4 are stacked in this order on the insulating layer 19. That is, in the manufacturing method of the thermal printhead C1, the wiring layer 3 is formed on the insulating layer 19, and then the resistor layer 4 is formed. In the manufacturing method of the thermal printhead A1, the resistor film 4K, the first conductor film 301K, and the second conductor film 302K are formed in this order, and then each of the first conductor film 301K and the second conductor film 302K is partially removed, for example, by etching. Because the resistor film 4K, the first conductor film 301K, and the second conductor film 302K are etched sequentially after they are formed, transport between a film-forming apparatus and an etching apparatus is not required, and the transport work can be reduced. However, when each of the first conductor film 301K and the second conductor film 302K is etched, the resistor film 4K is also subjected to this etching. Therefore, depending on the material of the resistor film 4K and the etching methods for the first conductor film 301K and the second conductor film 302K, the resistor film 4K may be damaged. On the other hand, in the thermal printhead C1, the resistor film 4K (resistor layer 4) is formed after processing the first conductor layer 301 and the second conductor layer 302 (first partial removal step and second partial removal step), so the resistor film 4K is not damaged. In other words, processing damage to the resistor layer 4 (each heat generating portion 41) can be reduced.

[0081] In the third embodiment, the stacking order of the first conductor layer 301 and the second conductor layer 302 is not limited to the above example and may be reversed. Figures 24 and 25 show a thermal printhead C2 according to such a modification. Figure 24 is a cross-sectional view of a main portion of the thermal printhead C2 and corresponds to Figure 22. Figure 25 is an enlarged cross-sectional view of a main portion of the thermal printhead C2 and corresponds to Figure 23.

[0082] 24 and 25, the thermal printhead C2 has a wiring layer 3 stacked on an insulating layer 19, followed by a second conductor layer 302 and a first conductor layer 301, and a resistor layer 4 stacked on the first conductor layer 301. In the thermal printhead C2, the sub-heat generating portions 35A and 35B are formed by the portions of the first conductor layer 301 that are not formed on the second conductor layer 302, i.e., the portions of the first conductor layer 301 that are in contact with the insulating layer 19.

[0083] The thermal printhead C2 can also achieve the same effects as the thermal printhead C1.

[0084] 22 and 24, in the thermal printheads C1 and C2, a resistor layer 4 is interposed between the individual pads 311 and the wiring layer 3, but due to the size of the individual pads 311 in a plan view and the thinness of the resistor layer 4, this does not have a significant effect on the conductivity between the individual pads 311 and the wiring layer 3. In order to improve the conductivity between the individual pads 311 and the wiring layer 3, it is desirable not to provide a resistor layer 4 therebetween.

[0085] In the thermal printheads C1 and C2, as in the second embodiment (see Figure 20) described above, the first main surface 11 may not be present in the region downstream of the convex portion 13 in the sub-scanning direction y, or as in the modified example of the second embodiment (see Figure 21), a very small amount of the first main surface 11 may be present.

[0086] Figures 26 and 27 show a thermal printhead D1 according to the fourth embodiment. Figure 26 is an enlarged plan view of the thermal printhead D1, corresponding to Figure 3 in the first embodiment. Figure 27 is an enlarged cross-sectional view of the thermal printhead D1, corresponding to Figure 6 in the first embodiment.

[0087] As shown in FIGS. 26 and 27, the thermal printhead D1 differs from the thermal printhead A1 in the formation ranges of the resistor layer 4 and the first conductor layer 301. Specifically, as shown in FIG. 27, the resistor layer 4 is formed from the top portion 130 to the first inclined portion 131B, but is not formed on the first inclined portion 131A, the pair of second inclined portions 132A and 132B, or the first main surface 11. A portion of the first conductor layer 301 is formed on the resistor layer 4, and the other portion is formed directly on the insulating layer 19. The first conductor layer 301 is either formed on the top portion 130 or formed from the first inclined portion 131B to the second inclined portion 132B. The second conductor layer 302 is partially formed on the first conductor layer 301, and the other portion is formed directly on the insulating layer 19. The second conductor layer 302 may be formed across the first main surface 11 from the top 130 via the first inclined portion 131A and the second inclined portion 132A, or may be formed across the first main surface 11 from the second inclined portion 132B. As described above, the thermal printhead D1 has the wiring layer 3 (the first conductor layer 301 and the second conductor layer 302) and the resistor layer 4, which are formed more locally than in the thermal printhead A1. In the thermal printhead D1, the sub-heating portions 35A and 35B are formed by the portions of the first conductor layer 301 exposed from the second conductor layer 302, i.e., the portions that do not overlap the second conductor layer 302 when viewed in the z direction. Furthermore, the conductive portions 36A and 36B are formed by the portions where the second conductor layer 302 is formed.

[0088] In the manufacturing method of the thermal printhead D1, the resistor film forming process, the resistor film partial removal process, the first film forming process, the first partial removal process, the second film forming process, and the second partial removal process are performed in this order. In this way, the resistor layer 4 and the wiring layer 3 (the first conductor layer 301 and the second conductor layer 302) are formed in this order. In other words, the wiring layer forming process is performed after the resistor layer forming process. As a result, as shown in FIGS. 26 and 27, the resistor layer 4 and the first conductor layer 301 are formed locally in the thermal printhead D1 compared to the thermal printhead A1.

[0089] In the thermal printhead D1, as in the thermal printhead A1, each sub-heating element 35A, 35B is sandwiched between a heat-generating element 41 and a conductive element 36A, 36B. This makes it possible to reduce the temperature gradient in the sub-scanning direction y compared to when each heat-generating element 41 and each conductive element 36A, 36B are adjacent to each other. Therefore, as in the first embodiment, the durability and reliability of the thermal printhead D1 can be improved.

[0090] 26 and 27, in thermal printhead D1, the resistor layer 4 and first conductor layer 301 are arranged locally compared to thermal printhead A1. This makes it easier to adjust the positions and sizes of the heat-generating portion 41, sub-heat-generating portions 35A and 35B, and conductive portions 36A and 36B in thermal printhead D1, and also allows for lower material costs than thermal printhead A1.

[0091] Although thermal printhead D1 illustrates an example in which the resistor layer 4 and first conductor layer 301 are locally arranged in thermal printhead A1, this is not limiting. For example, the resistor layer 4 and first conductor layer 301 may be locally arranged in each of thermal printheads C1 and C2. FIG. 28 illustrates a thermal printhead C1 in which the resistor layer 4 and first conductor layer 301 are locally arranged, and is an enlarged cross-sectional view of a thermal printhead D2 according to this modification. FIG. 29 illustrates a thermal printhead C2 in which the resistor layer 4 and first conductor layer 301 are locally arranged, and is an enlarged cross-sectional view of a thermal printhead D3 according to this modification.

[0092] 28 and 29, the resistor layer 4 and the first conductor layer 301 are also locally arranged in the thermal printheads D2 and D3. Therefore, as with the thermal printhead D1, the positions and sizes of the heat-generating portion 41, the sub-heat-generating portions 35A and 35B, and the conductive portions 36A and 36B can be easily adjusted, and the material costs can be lower than those of the thermal printhead A1. In particular, in the modification shown in FIGS. 28 and 29, the resistor layer formation step is performed after the wiring layer formation step (i.e., the resistor film formation step is performed after the first partial removal step and the second partial removal step), and therefore, processing damage to the resistor layer 4 can be reduced, as with the thermal printheads C1 and C2 according to the third embodiment and its modifications (see FIGS. 22 to 25).

[0093] In thermal printheads D1 to D3, similar to the second embodiment (see FIG. 20), the first main surface 11 may not be present in the region downstream of the convex portions 13 in the sub-scanning direction y, or similar to the modified example of the second embodiment (see FIG. 21), only a small amount of the first main surface 11 may be present. For example, FIG. 30 shows a case in which the thermal printhead D1 has only a small amount of the first main surface 11, similar to the modified example of the second embodiment. FIG. 30 is an enlarged cross-sectional view of a main portion of a thermal printhead according to this modified example.

[0094] Figures 31 and 32 show a thermal printhead E1 according to the fifth embodiment. Figure 31 is an enlarged cross-sectional view of a main part of the thermal printhead E1, corresponding to Figure 6 in the first embodiment. Figure 32 is an enlarged plan view of a main part of the thermal printhead E1, corresponding to Figure 3 in the first embodiment.

[0095] 31 and 32, the thermal printhead E1 differs from the thermal printhead A1 in the configuration of the wiring layer 3. The wiring layer 3 of the thermal printhead E1 is composed of a single conductor layer 300. In this embodiment, an example is shown in which the conductor layer 300 is formed instead of the first conductor layer 301 and the second conductor layer 302 in the thermal printhead A1. Similarly, in thermal printheads according to other embodiments, the conductor layer 300 may be formed instead of the first conductor layer 301 and the second conductor layer 302.

[0096] The conductor layer 300 is made of Cu, for example, similar to the second conductor layer 302. As shown in FIG. 31 , the conductor layer 300 includes a thick portion 300a and a thin portion 300b that are relatively different in thickness. The thick portion 300a is formed thicker than the thin portion 300b. Because the thin portion 300b has a smaller cross-sectional area than the thick portion 300a, the resistance value per unit length in the sub-scanning direction y of the thin portion 300b is greater than the resistance value per unit length in the sub-scanning direction y of the thick portion 300a. Furthermore, the resistance value per unit length in the sub-scanning direction y of the thin portion 300b is smaller than the resistance value per unit length in the sub-scanning direction y of the resistor layer 4 (each heat generating portion 41). Therefore, each of the sub-heat generating portions 35A and 35B is made of the thin portion 300b, and each of the conductive portions 36A and 36B is made of the thick portion 300a. The thickness of each of the thick portion 300a and the thin portion 300b is not particularly limited, but is configured so that the resistance value per unit length in the sub-scanning direction y satisfies the above-mentioned relationship.

[0097] In the thermal printhead E1, as in the thermal printhead A1, each sub-heating element 35A, 35B is sandwiched between a heat-generating element 41 and a conductive element 36A, 36B. This makes it possible to reduce the temperature gradient in the sub-scanning direction y compared to when each heat-generating element 41 and each conductive element 36A, 36B are adjacent to each other. Therefore, as in the first embodiment, the durability and reliability of the thermal printhead E1 can be improved.

[0098] In the fifth embodiment, the sub-heating elements 35A and 35B, i.e., the thin portions 300b, are rectangular when viewed in the thickness direction z. However, the present disclosure is not limited to this. For example, the thin portions 300b may be patterned. FIG. 33 is an enlarged plan view of a thermal printhead E2 according to such a modification, corresponding to FIG. 32. In the thermal printhead E2, as shown in FIG. 33, the thin portions 300b are patterned into a comb-like shape when viewed in the thickness direction z. The shape of the patterned thin portions 300b is not limited to the comb-like shape shown in FIG. 33. By patterning in this manner, the cross-sectional area of the conductor layer 300 in each of the sub-heating elements 35A and 35B can be reduced, thereby adjusting the resistance per unit length in the sub-scanning direction y of each of the sub-heating elements 35A and 35B. In the thermal printhead E2, the sub-heating elements 35A and 35B are patterned while thinning the thickness of the conductor layer 300 (i.e., while providing the thinned portions 300b), but the present disclosure is not limited to this. For example, the conductor layer 300 may be patterned while maintaining the thickness of the conductor layer 300 uniform (i.e., without providing the thinned portions 300b).

[0099] The thermal printhead, thermal printer, and thermal printhead manufacturing method 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 thermal printhead manufacturing method according to the present disclosure can be freely modified in various ways. The present disclosure includes the embodiments described in the following appendices. Appendix 1. a substrate made of a single crystal semiconductor and having a main surface facing in one direction in a thickness direction; a resistor layer supported by the substrate and having a plurality of heat generating portions arranged in a main scanning direction; a wiring layer supported by the substrate and constituting current paths to the plurality of heat generating portions; It is equipped with the wiring layer includes, for each of the plurality of heat generating portions, a conductive portion having a resistance value per unit length in the sub-scanning direction smaller than that of the heat generating portion, and a sub-heat generating portion having a resistance value per unit length in the sub-scanning direction intermediate between that of the heat generating portion and that of the conductive portion; the substrate has a protrusion protruding from the main surface and extending in a main scanning direction; the heat generating portion, the sub-heat generating portion, and the conductive portion are formed on the protrusion, The sub-heating portion is sandwiched between the heat-generating portion and the conductive portion in the sub-scanning direction. Appendix 2. the convex portion includes an apex portion that is farthest from the main surface, a first upstream inclined portion that is connected to the apex portion from the upstream side in the sub-scanning direction, and a first downstream inclined portion that is connected to the apex portion from the downstream side in the sub-scanning direction, the upstream first inclined portion and the downstream first inclined portion are each inclined at a first inclination angle with respect to the main surface, 2. The thermal printhead according to claim 1, wherein the heat generating portion is formed across the first downstream inclined portion and the peak. Appendix 3. the convex portion includes an upstream second inclined portion connected to the upstream first inclined portion on a side opposite to the peak in the sub-scanning direction, and a downstream second inclined portion connected to the downstream first inclined portion on a side opposite to the peak in the sub-scanning direction, the upstream second inclined portion and the downstream second inclined portion are each inclined at a second inclination angle with respect to the main surface, 3. The thermal printhead of claim 2, wherein the second tilt angle is greater than the first tilt angle. Appendix 4. The thermal printhead of claim 3, wherein the sub-heating section includes an upstream sub-heating section located upstream in the sub-scanning direction relative to the heat generating section, and a downstream sub-heating section located downstream in the sub-scanning direction. Appendix 5. A thermal printhead as described in Appendix 4, wherein the conductive portion includes an upstream conductive portion adjacent to the upstream sub-heating portion on the opposite side of the heat generating portion in the sub-scanning direction, and a downstream conductive portion adjacent to the downstream sub-heating portion on the opposite side of the heat generating portion in the sub-scanning direction. Appendix 6. 6. The thermal printhead according to claim 5, wherein the upstream sub-heating portion is formed on the top portion. Appendix 7. A thermal printhead as described in Appendix 6, wherein the upstream conductive portion is formed across the main surface from the top, via the upstream first inclined portion and the upstream second inclined portion. Appendix 8. 8. The thermal printhead according to claim 5, wherein the downstream sub-heating portion is formed across the downstream second inclined portion and the downstream first inclined portion. Appendix 9. 9. The thermal printhead according to claim 8, wherein the downstream conductive portion is formed on the downstream second inclined portion. Appendix 10. the wiring layer and the resistor layer at least partially overlap each other when viewed in the thickness direction, A thermal printhead described in any one of Appendix 1 to Appendix 9, wherein each of the plurality of heat generating portions is constituted by a portion of the resistor layer that does not overlap the wiring layer when viewed in the thickness direction. Appendix 11. the wiring layer includes a first conductor layer and a second conductor layer stacked in the thickness direction, the conductive portion is formed by a portion where the second conductor layer is formed, A thermal printhead as described in Appendix 10, wherein the sub-heating portion is formed by a portion of the first conductor layer that does not overlap the second conductor layer when viewed in the thickness direction. Appendix 12. the resistor layer is formed on the substrate, the first conductor layer is formed on the resistor layer while exposing a portion of the resistor layer; 12. The thermal printhead of claim 11, wherein the second conductive layer is formed on the first conductive layer while leaving a portion of the first conductive layer exposed. Appendix 13. the first conductor layer is formed on the substrate; the second conductor layer is formed on the first conductor layer while exposing a portion of the first conductor layer; A thermal printhead as described in Appendix 11, wherein the resistor layer is formed on the substrate while overlapping the first conductor layer exposed from the second conductor layer at least when viewed in the thickness direction. Appendix 14. 14. The thermal printhead according to claim 11, wherein the first conductor layer is thinner than the second conductor layer. Appendix 15. 15. The thermal printhead according to claim 11, wherein the first conductor layer is made of a material having a lower thermal conductivity than the second conductor layer. Appendix 16. the wiring layer includes a thick portion and a thin portion that are relatively different in size in the thickness direction, the sub-heating portion is constituted by the thin-walled portion, 11. The thermal printhead according to claim 10, wherein the conductive portion is constituted by the thick portion. Appendix 17. 17. The thermal printhead of claim 16, wherein the thin portion is patterned when viewed in the thickness direction. Appendix 18. 18. The thermal printhead according to any one of claims 1 to 17, wherein the single crystal semiconductor is Si. Appendix 19. A thermal printhead according to any one of Supplementary Note 1 to Supplementary Note 18; a platen facing the thermal printhead. Appendix 20. a substrate preparation step of preparing a substrate made of a single crystal semiconductor; a substrate processing step of forming, on the substrate, a main surface facing one side in a thickness direction and a convex portion protruding from the main surface and extending in a main scanning direction; a resistor layer forming step of forming a resistor layer supported by the substrate and having a plurality of heat generating portions arranged in a main scanning direction; a wiring layer forming step of forming a wiring layer supported by the substrate and constituting current paths to the plurality of heat generating portions; It is equipped with the wiring layer includes, for each of the plurality of heat generating portions, a conductive portion having a resistance value per unit length in the sub-scanning direction smaller than that of the heat generating portion, and a sub-heat generating portion having a resistance value per unit length in the sub-scanning direction intermediate between that of the heat generating portion and that of the conductive portion; the heat generating portion, the sub-heat generating portion, and the conductive portion are formed on the protrusion, A method for manufacturing a thermal printhead, wherein the sub-heating portion is sandwiched between the heat-generating portion and the conductive portion in the sub-scanning direction. Appendix 21. the resistor layer forming step includes a resistor film forming step of forming a resistor film, the wiring layer forming step includes a first film forming step of forming a first conductor film, a first partial removal step of partially removing the first conductor film to form a first conductor layer, a second film forming step of forming a second conductor film, and a second partial removal step of partially removing the second conductor film to form a second conductor layer, the first conductor layer and the second conductor layer are stacked in the thickness direction, the conductive portion is formed by a portion where the second conductor layer is formed, A method for manufacturing a thermal printhead described in Appendix 20, wherein the sub-heating portion is composed of a portion of the first conductor layer that does not overlap the second conductor layer when viewed in the thickness direction. Appendix 22. 22. The method for manufacturing a thermal printhead according to claim 21, wherein the resistor film forming step is performed before the wiring layer forming step. Appendix 23. 22. The method for manufacturing a thermal printhead according to claim 21, wherein the resistor film forming step is performed after the wiring layer forming step. [Explanation of symbols]

[0100] A1, B1, B2, C1, C2, D1 to D3, E1, E2: Thermal print heads 1: Head substrate 1K: Substrate material 11, 11K: First main surface 12, 12K: First back surface 13,13K: Convex part 130,130K: Top 131A, 131B: First slope part 132A, 132B: Second slope part 132K: Inclined portion 19: Insulating layer 2: Protective layer 21: Pad opening 3: Wiring layer 300: Conductor layer 300a: thick portion 300b: thin portion 301: first conductor layer 302: Second conductor layer 3K: Wiring film 301K: First conductor film 302K: Second conductive film 31: Individual electrode 311: Individual pad 32: Common electrode 323: Connecting portion 324: Strip portion 325: Branching portion 33: Relay electrode 35A, 35B: Sub-heating portion 36A, 36B: Conductive part 4: Resistor layer 4K: Resistor film 41: Heat generating part 5: Connection board 51: Second main surface 52: Second rear surface 59: Connector 61: Wire 62: Wire 7: Driver IC 78: Protective resin 8: Heat dissipation member 81: First support surface 82: Second support surface Pr: Thermal printer 91: Platen roller 910: Contact center x: Main scanning direction y: Sub-scanning direction z: Thickness direction

Claims

1. a substrate made of a single crystal semiconductor and having a main surface facing in one direction in a thickness direction; a resistor layer supported by the substrate and having a plurality of heat generating portions arranged in a main scanning direction; a wiring layer supported by the substrate and constituting current paths to the plurality of heat generating portions; It is equipped with the wiring layer includes, for each of the plurality of heat generating portions, a conductive portion having a resistance value per unit length in the sub-scanning direction smaller than that of the heat generating portion, and a sub-heat generating portion having a resistance value per unit length in the sub-scanning direction intermediate between that of the heat generating portion and that of the conductive portion; the substrate has a protrusion protruding from the main surface and extending in a main scanning direction; the heat generating portion, the sub-heat generating portion, and the conductive portion are formed on the protrusion, the sub-heating portion is sandwiched between the heat-generating portion and the conductive portion in the sub-scanning direction, the convex portion includes an apex portion that is far from the main surface, a first upstream inclined portion that is connected to the apex portion from the upstream side in the sub-scanning direction, and a second upstream inclined portion that is connected to the upstream first inclined portion on the opposite side to the apex portion in the sub-scanning direction, the sub-heating portion includes an upstream sub-heating portion located upstream in the sub-scanning direction with respect to the heat generating portion, the conductive portion includes an upstream conductive portion adjacent to the upstream sub-heating portion on the opposite side to the heat-generating portion in the sub-scanning direction, the upstream conductive portion is formed across the main surface from the top portion, via the upstream first inclined portion and the upstream second inclined portion.

2. the convex portion includes a downstream-side first inclined portion that is connected to the apex portion from the downstream side in the sub-scanning direction, the upstream first inclined portion and the downstream first inclined portion are each inclined at a first inclination angle with respect to the main surface, The thermal printhead according to claim 1 , wherein the heat generating portion is formed across the first downstream inclined portion and the peak portion.

3. the convex portion includes a downstream second inclined portion that is connected to the downstream first inclined portion on the opposite side to the peak in the sub-scanning direction, the upstream second inclined portion and the downstream second inclined portion are each inclined at a second inclination angle with respect to the main surface, The thermal printhead of claim 2 , wherein the second tilt angle is greater than the first tilt angle.

4. 4. The thermal printhead according to claim 3, wherein the sub-heating portion includes a downstream sub-heating portion located downstream in the sub-scanning direction from the heat generating portion.

5. 5. The thermal printhead according to claim 4, wherein the conductive portion includes a downstream conductive portion adjacent to the downstream sub-heating portion on the opposite side of the heat generating portion in the sub-scanning direction.

6. 6. The thermal printhead according to claim 5, wherein the upstream sub-heating portion is formed on the top portion.

7. 7. The thermal printhead according to claim 5, wherein the downstream sub-heating portion is formed across the downstream second inclined portion and the downstream first inclined portion.

8. The thermal printhead according to claim 7 , wherein the downstream conductive portion is formed on the downstream second inclined portion.

9. the wiring layer and the resistor layer at least partially overlap each other when viewed in the thickness direction, 9. The thermal printhead according to claim 1, wherein each of the plurality of heat generating portions is formed by a portion of the resistor layer that does not overlap the wiring layer when viewed in the thickness direction.

10. the wiring layer includes a first conductor layer and a second conductor layer stacked in the thickness direction, the conductive portion is configured by a portion on which the second conductor layer is formed, 10. The thermal printhead according to claim 9, wherein the sub-heating portion is formed by a portion of the first conductor layer that does not overlap the second conductor layer when viewed in the thickness direction.

11. Further comprising an insulating layer covering the main surface and the protrusion, a portion of the first conductor layer and a portion of the second conductor layer are in contact with the insulating layer; a portion of the first conductor layer and a portion of the resistor layer overlap each other in the thickness direction; The thermal printhead according to claim 10 , wherein a portion of the first conductor layer and a portion of the second conductor layer overlap each other when viewed in the thickness direction.

12. In a region where a portion of the first conductor layer and a portion of the resistor layer overlap in the thickness direction, a portion of the first conductor layer overlaps a portion of the resistor layer, 12. A thermal printhead as described in claim 11, wherein in a region where a portion of the first conductor layer and a portion of the second conductor layer overlap in the thickness direction, a portion of the second conductor layer overlaps a portion of the first conductor layer.

13. In a region where a portion of the first conductor layer and a portion of the resistor layer overlap in the thickness direction, a portion of the resistor layer overlaps a portion of the first conductor layer, 12. A thermal printhead as described in claim 11, wherein in a region where a portion of the first conductor layer and a portion of the second conductor layer overlap in the thickness direction, a portion of the second conductor layer overlaps a portion of the first conductor layer.

14. In a region where a portion of the first conductor layer and a portion of the resistor layer overlap in the thickness direction, a portion of the resistor layer overlaps a portion of the first conductor layer, 12. A thermal printhead as described in claim 11, wherein in a region where a portion of the first conductor layer and a portion of the second conductor layer overlap in the thickness direction, a portion of the first conductor layer overlaps a portion of the second conductor layer.

15. the resistor layer is formed on the substrate, the first conductor layer is formed on the resistor layer while exposing a portion of the resistor layer; The thermal printhead according to claim 10 , wherein the second conductor layer is formed on the first conductor layer while leaving a portion of the first conductor layer exposed.

16. the first conductor layer is formed on the substrate; the second conductor layer is formed on the first conductor layer while exposing a portion of the first conductor layer; 11. The thermal printhead according to claim 10, wherein the resistor layer is formed on the substrate so as to overlap the first conductor layer exposed from the second conductor layer at least when viewed in the thickness direction.

17. 13. The thermal printhead according to claim 10, wherein the first conductor layer is thinner than the second conductor layer.

18. 14. The thermal printhead according to claim 10, wherein the first conductor layer is made of a material having a lower thermal conductivity than the second conductor layer.

19. the wiring layer includes a thick portion and a thin portion that are relatively different in size in the thickness direction, the sub-heating portion is constituted by the thin-walled portion, 10. The thermal printhead according to claim 9, wherein the conductive portion is constituted by the thick portion.

20. The thermal printhead according to claim 19 , wherein the thin portion is patterned when viewed in the thickness direction.

21. 21. The thermal printhead according to claim 1, wherein the single crystal semiconductor is Si.

22. A thermal printhead according to any one of claims 1 to 21; a platen facing the thermal printhead; A thermal printer comprising:

23. A substrate made of a single crystal semiconductor and having a main surface facing in one direction in the thickness direction; a resistor layer supported by the substrate and having a plurality of heat generating portions arranged in a main scanning direction; a wiring layer supported by the substrate and constituting current paths to the plurality of heat generating portions; It is equipped with the wiring layer includes, for each of the plurality of heat generating portions, a conductive portion having a resistance value per unit length in the sub-scanning direction smaller than that of the heat generating portion, and a sub-heat generating portion having a resistance value per unit length in the sub-scanning direction intermediate between that of the heat generating portion and that of the conductive portion; the substrate has a protrusion protruding from the main surface and extending in a main scanning direction; the heat generating portion, the sub-heat generating portion, and the conductive portion are formed on the protrusion, the sub-heating portion is sandwiched between the heat-generating portion and the conductive portion in the sub-scanning direction, the wiring layer and the resistor layer at least partially overlap each other when viewed in the thickness direction, each of the plurality of heat generating portions is formed by a portion of the resistor layer that does not overlap with the wiring layer when viewed in the thickness direction; the wiring layer includes a first conductor layer and a second conductor layer stacked in the thickness direction, the conductive portion is configured by a portion on which the second conductor layer is formed, the sub-heating portion is configured by a portion of the first conductor layer that does not overlap the second conductor layer when viewed in the thickness direction, the first conductor layer is formed on the substrate; the second conductor layer is formed on the first conductor layer while exposing a portion of the first conductor layer; The resistor layer is formed on the substrate while overlapping the first conductor layer exposed from the second conductor layer at least when viewed in the thickness direction.

24. a substrate preparation step of preparing a substrate made of a single crystal semiconductor; a substrate processing step of forming, on the substrate, a main surface facing one side in a thickness direction and a convex portion protruding from the main surface and extending in a main scanning direction; a resistor layer forming step of forming a resistor layer supported by the substrate and having a plurality of heat generating portions arranged in a main scanning direction; a wiring layer forming step of forming a wiring layer supported by the substrate and constituting current paths to the plurality of heat generating portions; It is equipped with the wiring layer includes, for each of the plurality of heat generating portions, a conductive portion having a resistance value per unit length in the sub-scanning direction smaller than that of the heat generating portion, and a sub-heat generating portion having a resistance value per unit length in the sub-scanning direction intermediate between that of the heat generating portion and that of the conductive portion; the heat generating portion, the sub-heat generating portion, and the conductive portion are formed on the protrusion, the sub-heating portion is sandwiched between the heat-generating portion and the conductive portion in the sub-scanning direction, the resistor layer forming step includes a resistor film forming step of forming a resistor film, the wiring layer forming step includes a first film forming step of forming a first conductor film, a first partial removal step of partially removing the first conductor film to form a first conductor layer, a second film forming step of forming a second conductor film, and a second partial removal step of partially removing the second conductor film to form a second conductor layer, the first conductor layer and the second conductor layer are stacked in the thickness direction, the conductive portion is configured by a portion on which the second conductor layer is formed, the sub-heating portion is configured by a portion of the first conductor layer that does not overlap the second conductor layer when viewed in the thickness direction, The resistor film forming step is performed after the wiring layer forming step. A method for manufacturing a thermal printhead.

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