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

Abstract

To provide a thermal print head that can suppress generation of foreign matters and reduce deterioration in printing quality.SOLUTION: A thermal print head A1 includes: a head substrate 1 having a main surface 11 facing one side in a thickness direction z; a resistor layer 4 including a plurality of heating portions 41 arranged in a main scanning direction x and supported by the head substrate 1; and a wiring layer 3 forming a power path to the plurality of heating portions 41 and supported by the head substrate 1. The head substrate 1 includes a convex portion 13 protruding from the main surface 11 and extending in the main scanning direction x. The convex portion 13 includes a flat first surface (second inclined plane 142) on which each of the plurality of heating portions 41 is disposed, and a first curved convex surface 151 connected to the first surface.SELECTED DRAWING: Figure 7

Description

[Technical Field]

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

[0002] Patent Document 1 discloses an example of a conventional thermal printhead. The thermal printhead described in this document includes a semiconductor substrate, a resistor layer having multiple heat generating elements, and a wiring layer included in a conductive path for supplying electricity to the multiple heat generating elements. The semiconductor substrate includes silicon. The resistor layer and the wiring layer are supported by the semiconductor substrate. The semiconductor substrate has a convex portion. The semiconductor substrate has a main surface and a convex portion. The convex portion is a portion that protrudes from the main surface in the thickness direction z. The multiple heat generating elements are arranged on the convex portion.

[0003] A printing medium (such as thermal paper) is pressed against the heat generating elements by a platen roller arranged opposite the heat generating elements. The heat from each of the heat generating elements prints dots on the printing medium. The printing medium is transported in the sub-scanning direction by the rotation of the platen roller. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-43425 Summary of the Invention [Problem to be solved by the invention]

[0005] Foreign matter can be generated during the transport of the print medium. Such foreign matter can be scrapes from the print medium (e.g., paper scraps) or scrapes from the surface of the thermal printhead. If such foreign matter adheres to the heat generating elements, it can impede the transfer of heat from the heat generating elements to the print medium, resulting in reduced print quality.

[0006] The present disclosure was conceived in light of the above circumstances, and aims to provide a thermal printhead that can suppress the generation of foreign matter and reduce degradation of print quality, as well as a thermal printer equipped with the thermal printhead and a method for manufacturing the thermal printhead. [Means for solving the problem]

[0007] A thermal printhead provided by a first aspect of the present disclosure comprises a substrate having a main surface facing in one direction in the thickness direction, a resistor layer having a plurality of heat generating elements arranged in a main scanning direction and supported by the substrate, and a wiring layer forming a current path to the plurality of heat generating elements and supported by the substrate, wherein the substrate includes a convex portion protruding from the main surface and extending in the main scanning direction, and the convex portion has a flat first surface on which each of the plurality of heat generating elements is arranged, and a first curved convex surface connected to the first surface.

[0008] 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 and transporting a print medium in a sub-scanning direction.

[0009] 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 a 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, wherein the convex portion has a flat first surface on which each of the plurality of heat generating elements is arranged and a first curved convex surface connected to the first surface, and the substrate processing step comprises a first step of forming an intermediate convex body having the first surface and protruding from the main surface, and a second step of forming the first curved convex surface on the intermediate convex body. [Effects of the Invention]

[0010] The thermal printhead of the present disclosure can suppress the generation of foreign matter and the deterioration of print quality. The thermal printer of the present disclosure also suppresses the generation of foreign matter and the deterioration of print quality. Furthermore, the method for manufacturing a thermal printhead of the present disclosure can manufacture a thermal printhead in which the generation of foreign matter and the deterioration of print quality are suppressed. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a plan view showing a thermal printhead according to an embodiment. [Figure 2] FIG. 2 is a partially enlarged view of a part of the plan view shown in FIG. [Figure 3] FIG. 3 is an enlarged plan view of a main part (region III) of FIG. [Figure 4] 4 is a partially enlarged cross-sectional view of a thermal printer including a thermal printhead according to an embodiment, taken along line IV-IV in FIG. [Figure 5] 5 is a partially enlarged view of a part of the cross section shown in FIG. 4, taken along line VV in FIG. [Figure 6] FIG. 6 is a partially enlarged view of a part of FIG. [Figure 7] FIG. 7 is an enlarged cross-sectional view of a main part of FIG. [Figure 8] FIG. 8 is a flowchart illustrating an example of a method for manufacturing a thermal printhead according to an embodiment. [Figure 9] FIG. 9 is a cross-sectional view showing a step of the method for manufacturing a thermal printhead according to an embodiment. [Figure 10] FIG. 10 is a cross-sectional view of a main part showing one step of a method for manufacturing a thermal printhead according to an embodiment. [Figure 11] FIG. 11 is a cross-sectional view of a main part showing one step of a method for manufacturing a thermal printhead according to an embodiment. [Figure 12] FIG. 12 is a cross-sectional view of a main part showing one step of a method for manufacturing a thermal printhead according to an embodiment. [Figure 13] FIG. 13 is a cross-sectional view of a main part showing one step of a method for manufacturing a thermal printhead according to an embodiment. [Figure 14] FIG. 14 is a cross-sectional view showing a step of a method for manufacturing a thermal printhead according to an embodiment. [Figure 15] FIG. 15 is a cross-sectional view showing a step of a method for manufacturing a thermal printhead according to an embodiment. [Figure 16] FIG. 16 is a cross-sectional view showing a step of a method for manufacturing a thermal printhead according to an embodiment. [Figure 17] FIG. 17 is a cross-sectional view showing a step of a method for manufacturing a thermal printhead according to an embodiment. [Figure 18] FIG. 18 is a cross-sectional view showing a step of a method for manufacturing a thermal printhead according to an embodiment. [Figure 19] FIG. 19 is a cross-sectional view of a main part showing one step of a manufacturing method for a modified thermal printhead. [Figure 20] FIG. 20 is a cross-sectional view of a main part of a thermal printhead according to a modified example, and corresponds to the cross section of FIG. [Figure 21] FIG. 21 is a cross-sectional view of a main part of a thermal printhead according to a modified example, and corresponds to the cross section of FIG. [Figure 22] FIG. 22 is a cross-sectional view of a main part of a thermal printhead according to a modified example, and corresponds to the cross section of FIG. [Figure 23] FIG. 23 is a partially enlarged cross-sectional view of a thermal printer including a thermal printhead according to an embodiment, and corresponds to the cross section of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] Preferred embodiments of the thermal printhead, thermal printer, and method of manufacturing a thermal printhead of the present disclosure are described below with reference to the drawings. Hereinafter, identical or similar components will be designated by the same reference numerals, and redundant description will be omitted. Terms such as "first," "second," and "third" in this disclosure are used merely as labels and are not intended to necessarily assign any rank to the objects they refer to.

[0013] In this disclosure, unless otherwise specified, "a certain object A is formed on a certain object B" and "a certain object A is formed on (an object) B" include "a certain object A is formed directly on a certain object B" and "a certain object A is formed on a certain object B with another object interposed between the certain object A and the certain object B." Similarly, "a certain object A is disposed on a certain object B" and "a certain object A is disposed on (an object) B" include "a certain object A is disposed directly on a certain object B" and "a certain object A is disposed on a certain object B with another object interposed between the certain object A and the certain object B" unless otherwise specified. Similarly, "a certain object A is located on (an object) B" includes "a certain object A is in contact with a certain object B and is located on (an object) B" and "a certain object A is located on (an object) B with another object interposed between the certain object A and the certain object B." Additionally, unless otherwise specified, "when viewed from a certain direction, object A overlaps object B" includes "object A overlaps the entirety of object B" and "object A overlaps part of object B."

[0014] 1 to 7 show a thermal printhead A1 according to an 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 99. The thermal printer Pr may be either a thermal printer or a thermal transfer printer. Examples of the print medium 99 include printing and information paper and plastic cards. For example, a thermal printer Pr uses thermal paper for creating barcode sheets and receipts as the print medium 99. The thermal printer Pr includes a thermal printhead A1 and a platen roller 91. The platen roller 91 faces the thermal printhead A1. The thermal printer Pr sandwiches a print medium 99 between a thermal printhead A1 and a platen roller 91, and the platen roller 91 transports the print medium 99 in the sub-scanning direction. Alternatively, a flat platen made of rubber may be used instead of the platen roller 91. This platen includes a portion of a cylindrical rubber with a large radius of curvature that is arch-shaped in cross section. In this disclosure, the term "platen" includes both the platen roller 91 and a flat platen.

[0015] The head substrate 1 supports the wiring layer 3 and the resistor layer 4. The head substrate 1 is an elongated rectangle with the primary 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. Furthermore, one side of the thickness direction z may be referred to as the upper side and the other side as the lower side. However, terms such as "upper," "lower," "upper," "lower," "upper surface," and "lower surface" indicate the relative positional relationship of each component in the thickness direction z and do not necessarily define the relationship with the direction of gravity. The size of the head substrate 1 is not particularly limited, but, for example, the thickness (thickness direction z dimension) is 725 μm, the primary scanning direction x dimension is 50 mm to 150 mm, and the secondary scanning direction y dimension is 2.0 mm to 5.0 mm.

[0016] The head substrate 1 is made of a single crystal semiconductor, such as Si (silicon). As shown in FIGS. 4 and 5, the head substrate 1 has a main surface 11 and a back surface 12. The main surface 11 and the back surface 12 are spaced apart in the thickness direction z and face opposite each other in the thickness direction z. The wiring layer 3 and the resistor layer 4 are provided on the main surface 11 side. The head substrate 1 corresponds to the "substrate" described in the claims.

[0017] The head substrate 1 has protrusions 13. As shown in Figs. 4 to 7, the protrusions 13 protrude from the main surface 11 in the thickness direction z, and as shown in Figs. 2 and 3, extend long in the main scanning direction x. In the example shown, the protrusions 13 are formed upstream of the head substrate 1 in the sub-scanning direction y. The protrusions 13 are part of the head substrate 1 and are therefore made of Si, a single-crystal semiconductor.

[0018] 3, 6, and 7, the convex portion 13 has a top surface 140, a first inclined surface 141, a second inclined surface 142, a third inclined surface 143, a fourth inclined surface 144, a first curved convex surface 151, a second curved convex surface 152, a third curved convex surface 153, a fourth curved convex surface 154, a first curved concave surface 161, and a second curved concave surface 162. For ease of understanding, the boundaries of these surfaces are indicated by black circles in FIG.

[0019] 6 and 7, the top surface 140 is the portion of the protrusion 13 that is farthest from the main surface 11. The top surface 140 is, for example, approximately parallel to the main surface 11. When viewed in the thickness direction z, the top surface 140 has an elongated rectangular shape extending in the main scanning direction x. The top surface 140 is flat.

[0020] As shown in FIGS. 3, 6, and 7, the second inclined surface 142 and the fourth inclined surface 144 are located on either side of the top surface 140 in the sub-scanning direction y. The second inclined surface 142 is located upstream of the top surface 140 in the sub-scanning direction y. The fourth inclined surface 144 is located downstream of the top surface 140 in the sub-scanning direction y. The second inclined surface 142 and the fourth inclined surface 144 are both flat. As shown in FIG. 7, the second inclined surface 142 and the fourth inclined surface 144 are each inclined at a first inclination angle α1 with respect to the main surface 11. When viewed in the thickness direction z, the second inclined surface 142 and the fourth inclined surface 144 each have an elongated rectangular shape extending long in the main scanning direction x. As can be seen from FIGS. 4 to 6, for example, the platen roller 91 is disposed so that a normal 910 of the platen roller 91 overlaps with a perpendicular to the second inclined surface 142. The protrusion 13 may have inclined portions (not shown) that are connected to the second inclined surface 142 and the fourth inclined surface 144 and are adjacent to both ends of the top surface 140 in the main scanning direction x.

[0021] As shown in FIGS. 3 , 6 , and 7 , the first inclined surface 141 and the third inclined surface 143 are located on the opposite side of the top surface 140 from the second inclined surface 142 and the fourth inclined surface 144 in the sub-scanning direction y. The first inclined surface 141 is located between the main surface 11 and the second inclined surface 142 in the sub-scanning direction y. The third inclined surface 143 is located between the main surface 11 and the fourth inclined surface 144 in the sub-scanning direction y. The first inclined surface 141 and the third inclined surface 143 are each flat. As shown in FIG. 7 , the first inclined surface 141 and the third inclined surface 143 are each inclined at a second inclination angle α2 with respect to the main surface 11. The second inclination angle α2 is larger than the first inclination angle α1. The first inclined surface 141 and the third inclined surface 143 each have an elongated rectangular shape 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 first inclined surface 141 and the third inclined surface 143 and are positioned outward in the main scanning direction x at both ends of the top surface 140 in the main scanning direction x.

[0022] In the thermal printhead A1, the main surface 11 of the head substrate 1 is a (100) plane. According to a manufacturing method example described below, the first inclination angle α1 (see FIG. 7) of each of the second inclined surface 142 and the fourth inclined surface 144 relative to the main surface 11 is, for example, 30.1 degrees. The second inclination angle α2 (see FIG. 7) of each of the first inclined surface 141 and the third inclined surface 143 relative to the main surface 11 is, for example, 54.7 degrees. The dimension of the protrusion 13 in the thickness direction z is, for example, not less than 150 μm and not more than 300 μm.

[0023] As shown in FIGS. 3, 6, and 7, the first curved convex surface 151 is interposed between and connected to the first inclined surface 141 and the second inclined surface 142. The second curved convex surface 152 is interposed between and connected to the second inclined surface 142 and the top surface 140. Therefore, the first curved convex surface 151 and the second curved convex surface 152 are connected to both sides of the second inclined surface 142 in the sub-scanning direction y. In this embodiment, the curvature of the first curved convex surface 151 and the curvature of the second curved convex surface 152 are approximately the same. In FIG. 7, approximate circles including the curves of the first curved convex surface 151 and the second curved convex surface 152 are respectively indicated by imaginary lines (two-dot chain lines).

[0024] As shown in FIGS. 3, 6, and 7, the third curved convex surface 153 is interposed between and connected to the third inclined surface 143 and the fourth inclined surface 144. The fourth curved convex surface 154 is interposed between and connected to the fourth inclined surface 144 and the top surface 140. Therefore, the third curved convex surface 153 and the fourth curved convex surface 154 are connected to both sides of the fourth inclined surface 144 in the sub-scanning direction y. In this embodiment, the curvature of the third curved convex surface 153 and the curvature of the fourth curved convex surface 154 are approximately the same. Furthermore, the curvature of the third curved convex surface 153 and the curvature of the first curved convex surface 151 are approximately the same, and the curvature of the fourth curved convex surface 154 and the second curved convex surface 152 are approximately the same. In FIG. 7, approximate circles including the curves of the third curved convex surface 153 and the fourth curved convex surface 154 are respectively indicated by imaginary lines (two-dot chain lines).

[0025] 3, 6, and 7, the first curved concave surface 161 is interposed between and connected to the main surface 11 and the first inclined surface 141. The second curved concave surface 162 is interposed between and connected to the main surface 11 and the third inclined surface 143.

[0026] The convex portion 13 has a flat first surface on which each of the multiple heat generating elements 41 is arranged. In the thermal printhead A1, the first surface is formed by the second inclined surface 142. As can be seen from FIGS. 4 and 6, in the thermal printhead A1, the print medium 99 is transported in the sub-scanning direction y from the first curved convex surface 151 toward the first surface (second inclined surface 142). Alternatively, the print medium 99 may be transported in the sub-scanning direction y from the second curved convex surface 152 toward the second inclined surface 142.

[0027] As shown in FIGS. 5 and 6, the insulating layer 19 covers the main surface 11 and the protrusions 13. The insulating layer 19 is formed to more reliably insulate the main surface 11 side of the head substrate 1. The insulating layer 19 is made of an insulating material, and an example of the insulating material is SiO2 (TEOS-SiO2) formed using TEOS (tetraethyl orthosilicate) as a raw material gas. Instead of TEOS-SiO2, for example, SiO2 or SiN formed by other methods 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).

[0028] 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 99. 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 in 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 -6 The 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).

[0029] Each heat generating portion 41 is disposed on the protrusion 13. In the example shown in FIG. 6, each heat generating portion 41 is formed across the first inclined surface 141 and the top surface 140. The upstream end of each heat generating portion 41 in the sub-scanning direction y is located on the first inclined surface 141, and the downstream end of each heat generating portion 41 in the sub-scanning direction y is located on the top surface 140. Alternatively, each heat generating portion 41 may be configured such that both its upstream end and its downstream end in the sub-scanning direction y are located on the second inclined surface 142. When viewed in the thickness direction z, the center of each heat generating portion 41 in the sub-scanning direction y overlaps with the second inclined surface 142. The positions of each heat generating portion 41 are not limited to those shown in FIG. 6 as long as they are disposed on the protrusion 13. For ease of understanding, each heat generating portion 41 in FIG. 3 is indicated by a dot pattern.

[0030] 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. As shown in FIGS. 5 and 6, the wiring layer 3 is stacked on the resistor layer 4. The shape and arrangement of the wiring layer 3 are not limited to the example shown in the drawings. The wiring layer 3 has a common electrode 31, a plurality of individual electrodes 32, and a plurality of relay electrodes 33.

[0031] The relay electrodes 33 are arranged at equal intervals in the main scanning direction x. Each of the relay electrodes 33 is located upstream of the heat generating portions 41 in the sub-scanning direction y.

[0032] As shown in FIGS. 2 and 3, each of the relay electrodes 33 includes two strip portions 331 and a connecting portion 332. The two strip portions 331 are strip-shaped and extend in the sub-scanning direction y. The two strip portions 331 are spaced apart in the main scanning direction x and are arranged substantially parallel to each other. Each of the two strip portions 331 is connected to an adjacent heat generating portion 41. In the example shown in FIGS. 2 and 3, each of the two strip portions 331 is connected to a respective heat generating portion 41 from the upstream side in the sub-scanning direction y. The dimensions of the two strip portions 331 in the main scanning direction x are substantially the same. The connecting portion 332 is connected to the end portions of the two strip portions 331 opposite in the sub-scanning direction y to the ends connected to each other. The connecting portion 332 is strip-shaped and extends in the main scanning direction x.

[0033] As shown in FIG. 2, the common electrode 31 includes a plurality of orthogonal portions 311, a plurality of branch portions 312, a plurality of strip portions 313, and a connecting portion 314. Each of the orthogonal portions 311 has a strip shape extending in the sub-scanning direction y. The orthogonal portions 311 are arranged at equal intervals in the main scanning direction x. A branch portion 312 and two strip portions 313 are provided at the leading end side (upstream side in the sub-scanning direction y) of each of the orthogonal portions 311. The two strip portions 313 are connected to adjacent heat generating portions 41. In the example shown in FIG. 2, each of the two strip portions 313 is connected to the heat generating portion 41 from the downstream side in the sub-scanning direction y. The dimension of each strip portion 313 in the main scanning direction x is approximately the same as the dimension of each strip portion 331 in the main scanning direction x. Furthermore, the strip portion 313 overlaps the strip portion 331 when viewed in the sub-scanning direction y. Each of the multiple branch portions 312 is connected to a tip of one of the straight portions 311. Each of the multiple branch portions 312 has an end opposite to the end connected to the two strip-shaped portions 313 in the sub-scanning direction y, to which a corresponding straight portion 311 is connected. The connecting portion 314 is located on the base end side (upstream side in the sub-scanning direction y) of the multiple straight portions 311 and extends along the main scanning direction x. Each of the multiple straight portions 311 is connected to the connecting portion 314. As shown in FIG. 2, the connecting portion 314 is connected to a connector 59 via a wire 61 and wiring 50 of the connection board 5, and a drive voltage is applied to the connecting portion 314.

[0034] Each of the individual electrodes 32 has an opposite polarity to the common electrode 31. As shown in FIG. 2, the individual electrodes 32 are arranged at intervals in the main scanning direction x. As shown in FIG. 2, each of the individual electrodes 32 includes a strip portion 321 and a pad portion 322. In each individual electrode 32, the strip portion 321 is strip-shaped and extends in the sub-scanning direction y, and is located downstream of the heat generating portion 41 in the sub-scanning direction y. In the example shown in FIG. 2, the strip portion 321 is connected to the heat generating portion 41 at its tip end (upstream side in the sub-scanning direction y). The dimension of the strip portion 321 in the main scanning direction x is approximately the same as the dimension of each strip portion 331 in the main scanning direction x. Furthermore, the upstream end of the strip portion 321 in the sub-scanning direction y overlaps the strip portion 331 as viewed in the sub-scanning direction y. In each individual electrode 32, the pad portion 322 is provided at the downstream end of the strip portion 321 in the sub-scanning direction y. The pad section 322 is connected to any one of the output pads 71 ​​(described later) of any one of the plurality of driver ICs 7 via a wire 61.

[0035] In the thermal printhead A1, as shown in FIG. 2, each orthogonal portion 311 of the common electrode 31 is sandwiched between the strip portions 321 of two individual electrodes 32. The heat-generating portion 41 to which one of the two strip portions 331 of each relay electrode 33 is connected is connected to the common electrode 31, and the heat-generating portion 41 to which the other of the two strip portions 331 of the relay electrode 33 is connected is connected to one of the multiple individual electrodes 32. Therefore, when an individual electrode 32 is energized, current flows through the heat-generating portion 41 connected to it and the heat-generating portion 41 connected to that heat-generating portion 41 via the relay electrode 33, causing these heat-generating portions 41 to generate heat. In other words, the two heat-generating portions 41 generate heat simultaneously. In the thermal printhead A1, when each heat-generating portion 41 is energized, a current flows through it in the sub-scanning direction y.

[0036] The wiring layer 3 (each of the common electrode 31, the plurality of individual electrodes 32, and the plurality of relay electrodes 33) is configured to include a first conductor layer 301 and a second conductor layer 302 stacked in the thickness direction z, as shown in Figures 5 and 6. For ease of understanding, each of the first conductor layer 301 and the second conductor layer 302 is hatched in Figure 3.

[0037] 5 and 6, the first conductor layer 301 is formed on the resistor layer 4. The first conductor layer 301 is made of a material whose resistance per unit length in the sub-scanning direction y is lower than that of the resistor layer 4 and higher than that of the second conductor layer 302. Preferably, the electrical conductivity of the first conductor layer 301 is, for example, 10 -6 ~10 -7 The 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 (Tl), 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.

[0038] As shown in Figures 5 and 6, 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 whose resistance value per unit length in the sub-scanning direction y is lower than that of 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.

[0039] In the thermal printhead A1, the following portions are formed by the first conductor layer 301 (either of the sub-heating portions 35A or 35B described below) exposed from the second conductor layer 302. As shown in FIG. 3 , these are portions of each strip-shaped portion 313 (common electrode 31), each strip-shaped portion 321 (each individual electrode 32), and each strip-shaped portion 331 (each relay electrode 33) that are connected to the respective heat-generating portions 41. That is, each strip-shaped portion 313 (common electrode 31), each strip-shaped portion 321 (each individual electrode 32), and each strip-shaped portion 331 (each relay electrode 33) includes a portion formed only by the first conductor layer 301 and a portion where the first conductor layer 301 and the second conductor layer 302 are laminated. Alternatively, the portion connected to the respective heat-generating portion 41 may be configured such that the second conductor layer 302 is laminated on the first conductor layer 301. In other words, each strip portion 313 (common electrode 31), each strip portion 321 (each individual electrode 32), and each strip portion 331 (each relay electrode 33) has the first conductor layer 301 and the second conductor layer 302 laminated over the entire formation area.

[0040] As shown in FIG. 6, the wiring layer 3 has a pair of sub-heat generating portions 35A and 35B for each of the plurality of heat generating portions 41.

[0041] As shown in FIG. 6, 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. In the example shown in FIG. 6, the sub-heating portion 35A is formed on the first inclined surface 141. The sub-heating portion 35B is formed on the top surface 140.

[0042] Since the resistance values ​​of the first conductor layer 301, the second conductor layer 302, and the resistor layer 4 have the above-mentioned relationship, the resistance value per unit length in the sub-scanning direction y of each sub-heating portion 35A, 35B is between that of each heat-generating portion 41 and the portion where the first conductor layer 301 and the second conductor layer 302 are laminated. As a result, when electricity is applied to each heat-generating portion 41, the amount of heat generated in each of the pair of sub-heating portions 35A, 35B is smaller than that of each heat-generating portion 41 and is greater than that of the portion where the first conductor layer 301 and the second conductor layer 302 are laminated.

[0043] The protective layer 2 covers the wiring layer 3 and the resistor layer 4 and protects them. The protective layer 2 is omitted in FIGS. 2 and 3. The protective layer 2 is made of an insulating material. For example, SiN (silicon nitride) is used as the insulating material. However, 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 would be 1.0 μm or more and 10 μm or less.

[0044] 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 pad openings 21 exposes a pad portion 322 of each individual electrode 32. Unlike the illustrated example, the 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 laminated in this order from the surface of the conductive material.

[0045] As shown in FIGS. 1 and 4, the connection board 5 is disposed downstream 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. As shown in FIG. 4, the connection board 5 has a main surface 51 and a back surface 52. The main surface 51 faces the same side as the main surface 11 of the head substrate 1, and the back surface 52 faces the same side as the back surface 12 of the head substrate 1. In this embodiment, the main surface 51 is positioned lower than the main surface 11 in the thickness direction z in the drawing.

[0046] A plurality of control electrodes 55 are formed on the connection substrate 5. As shown in FIG. 2, each control electrode 55 is arranged on the main surface 51, and is arranged downstream of the driver IC 7 in the sub-scanning direction y. Each control electrode 55 extends along the sub-scanning direction y. Each control electrode 55 is connected to one of the input pads 72 (described below) of the driver IC 7 via a wire 62, and is also connected to a connector 59 via wiring on the connection substrate 5.

[0047] Each of the plurality of wires 61, 62 provides electrical continuity between two portions spaced apart from each other. Each of the plurality of wires 61, 62 is a bonding wire. As shown in FIG. 2 , the plurality of wires 61 includes wires that provide electrical continuity between each individual electrode 32 (pad portion 322) and the driver IC 7, and wires that provide electrical continuity between the common electrode 31 (connecting portion 314) and the control electrode 55. The plurality of wires 62 includes wires that provide electrical continuity between the driver IC 7 and the control electrode 55.

[0048] Each of the multiple driver ICs 7 selectively energizes multiple heat generating elements 41. The number of driver ICs 7 can be changed as needed depending on the number of heat generating elements 41. The driver ICs 7 are controlled by signals input from outside the thermal printhead A1 via connector 59, wiring on the connection board 5, and each control electrode 55. Each driver IC 7 is mounted on the main surface 51 of the connection board 5 and connected to the multiple individual electrodes 32 and the multiple control electrodes 55 via multiple wires 61, 62.

[0049] As shown in FIG. 2, a plurality of output pads 71 ​​and a plurality of input pads 72 are arranged on the upper surface of each driver IC 7 (the surface facing upward in the thickness direction z). The plurality of output pads 71 ​​are terminals through which current flows to drive the heat generating portion 41. The plurality of output pads 71 ​​are arranged on the upper surface of each driver IC 7, near the upstream end in the sub-scanning direction y. Each output pad 71 is connected to the pad portion 322 of each individual electrode 32 via each wire 61. The plurality of input pads 72 are terminals to which main signals for controlling each driver IC 7 are input. The plurality of input pads 72 are arranged on the upper surface of each driver IC 7, near the downstream end in the sub-scanning direction y. Each input pad 72 is connected to each control electrode 55 via each wire 62.

[0050] The protective resin 78 covers the driver ICs 7 and the wires 61, 62. The protective resin 78 is made of, for example, an insulating resin and is, for example, black. As shown in FIGS. 1 and 4, the protective resin 78 is formed so as to straddle the head substrate 1 and the connection substrate 5.

[0051] The connector 59 is used to connect the thermal printhead A1 to the thermal printer Pr. As shown in Fig. 4, the connector 59 is attached to the connection board 5 and is connected to the input pads 72 of the driver IC 7 via the wiring pattern (not shown) of the connection board 5 and multiple control electrodes 55.

[0052] 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 (aluminum). As shown in FIG. 4, 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. The first support surface 81 and the second support surface 82 are arranged side by side in the sub-scanning direction y. The first support surface 81 is located upstream of the second support surface 82 in the sub-scanning direction y. As shown in FIG. 4, the back surface 12 of the head substrate 1 is joined to the first support surface 81, and the back surface 52 of the connection substrate 5 is joined to the second support surface 82.

[0053] Next, an example of a method for manufacturing the thermal printhead A1 will be described below with reference to FIGS.

[0054] As shown in FIG. 8, the manufacturing method of the thermal printhead A1 includes a substrate preparation process S11, a substrate processing process S12, an insulating layer formation process S13, a resistor film formation process S14, a wiring film formation process S15, a removal process S16, a protective layer formation process S17, a singulation process S181, and an assembly process S182.

[0055] [Substrate preparation step S11] First, as shown in FIG. 9, a substrate 10K is prepared. The substrate 10K is made of a single-crystal semiconductor and is, for example, a portion of a substantially circular Si wafer. One Si wafer includes multiple substrates 10K. The following figures illustrate one substrate 10K (head substrate 1) that is a portion of the Si wafer and corresponds to one thermal printhead A1. The thickness of the substrate 10K (in other words, the thickness of the Si wafer) is not particularly limited, but is, for example, approximately 725 μm. As shown in FIG. 9, the substrate 10K to be prepared has a main surface 11K and a back surface 12K facing opposite each other. The main surface 11K is a (100) plane.

[0056] [Substrate processing process S12] 10 to 13, the substrate 10K is processed to form the convex portions 13 on the substrate 10K. As shown in Fig. 8, the substrate processing step S12 includes a first step S121 and a second step S122.

[0057] In the first step S121, an intermediate convex body 13K is formed on the substrate 10K as shown in Figures 10 and 11. In the first step S121, etching is performed, for example, twice.

[0058] In the first etching, the main surface 11K is covered with a predetermined mask layer, and then anisotropic etching is performed using, for example, KOH (potassium hydroxide). The anisotropic etching agent may be TMAH (tetramethylammonium hydroxide) instead of KOH, but using KOH provides a faster processing speed (etching rate). The mask layer is then removed. As a result, as shown in FIG. 10, intermediate convex bodies 13K are formed on the substrate 10K. The intermediate convex bodies 13K protrude from the main surface 11K and extend in the main scanning direction x. At this point, the intermediate convex bodies 13K have a top surface 140K and a pair of primary inclined surfaces 141K and 143K. The top surface 140K is a surface parallel to the main surface 11K and is the same (100) plane as the main surface 11K. The top surface 140K is the portion that was covered with the mask layer. The pair of primary inclined surfaces 141K, 143K are located on either side of the top surface 140K in the sub-scanning direction y, and are each interposed between the top surface 140K and the main surface 11K. Each of the pair of primary inclined surfaces 141K, 143K is a flat surface inclined with respect to the top surface 140K and the main surface 11K. The angle formed by each of the pair of primary inclined surfaces 141K, 143K with respect to the main surface 11K and the top surface 140K is 54.7 degrees.

[0059] In the second etching, anisotropic etching is performed using, for example, TMAH. The chemical used in this anisotropic etching may be KOH instead of TMAH, but using TMAH results in smoother surfaces formed by the etching (e.g., a pair of secondary inclined surfaces 142K and 144K, which will be described later). This anisotropic etching forms a pair of secondary inclined surfaces 142K and 144K on the intermediate convex body 13K, as shown in FIG. 11 . That is, through two etchings, the intermediate convex body 13K is formed on the substrate 10K, having a top surface 140K, a pair of primary inclined surfaces 141K and 143K, and a pair of secondary inclined surfaces 142K and 144K. The secondary inclined surface 142K is the boundary between the top surface 140K and the primary inclined surface 141K, which is processed by the second etching (etching using TMAH). The secondary inclined surface 144K is a portion of the boundary between the top surface 140K and the primary inclined surface 143K that has been processed by a second etching (etching using TMAH). The angle α1 of each of the pair of secondary inclined surfaces 142K and 144K relative to the main surface 11K is 30.1 degrees, and the angle α2 of each of the pair of primary inclined surfaces 141K and 143K relative to the main surface 11K is 54.7 degrees. As shown in FIG. 11 , at the end of the first step S121, each of the corners 152K and 154K formed between the top surface 140K and each of the pair of secondary inclined surfaces 142K and 144K is angular. Similarly, each of the corners 151K and 153K formed between each of the pair of secondary inclined surfaces 142K and 144K and each of the pair of primary inclined surfaces 141K and 143K is angular.

[0060] In the second step S122, as shown in FIGS. 12 and 13, the intermediate convex body 13K is processed to form the convex portion 13. In the second step S122, first, as shown in FIG. 12, an oxide film 131K is formed by thermal oxidation on at least the surface (the surface on the upper side in the thickness direction z) of the intermediate convex body 13K. In the example shown in FIG. 12, in addition to the intermediate convex body 13K, the main surface 11K is also thermally oxidized. At this time, the reaction by thermal oxidation proceeds relatively faster in the direction perpendicular to the surface of the substrate 10K than in the direction parallel to the surface. Therefore, as shown in FIG. 12, the oxide film 131K is formed in an arc shape at each of the corners 151K to 154K, 161K, and 162K. The oxide film 131K also grows above the top surface 140K, the pair of primary inclined surfaces 141K and 143K, and the pair of secondary inclined surfaces 142K and 144K. The oxide film 131K is an oxide of the substrate 10K and is made of, for example, SiO2. The oxide film 131K is then removed. The oxide film 131K is removed by, for example, etching using HF. As a result, the convex portion 13 is formed as shown in FIG. 13. As described above, the convex portion 13 has a top surface 140, a first inclined surface 141, a second inclined surface 142, a third inclined surface 143, a fourth inclined surface 144, a first curved convex surface 151, a second curved convex surface 152, a third curved convex surface 153, a fourth curved convex surface 154, a first curved concave surface 161, and a second curved concave surface 162. For ease of understanding, the boundaries of these surfaces are indicated by black circles in FIG. 13. The resulting top surface 140, like the top surface 140K, is flat and parallel to the main surface 11. Similarly, the formed first inclined surface 141 is flat while maintaining the same inclination angle as the primary inclined surface 141K, and the second inclined surface 142 is flat while maintaining the same inclination angle as the secondary inclined surface 142K. Furthermore, the formed third inclined surface 143 is flat while maintaining the same inclination angle as the primary inclined surface 143K, and the fourth inclined surface 144 is flat while maintaining the same inclination angle as the secondary inclined surface 144K.

[0061] Through the above-described substrate processing step S12 (first step S121 and second step S122), a substrate 10 having a main surface 11, a back surface 12, and protrusions 13 is formed.

[0062] [Insulating layer forming step S13] 14, an insulating layer 19 is formed. The insulating layer 19 is formed, for example, by using CVD to deposit SiO formed using TEOS as a source gas on the substrate 10. The method for forming the insulating layer 19 is not limited to this. The formed insulating layer 19 covers the entire main surface 11 and the protrusions 13.

[0063] [Resistor film formation step S14] Next, the resistor film 4K is formed as shown in Fig. 15. In the resistor film forming step S14, a thin film of TaN is formed on the insulating layer 19 by, for example, sputtering. The method for forming the resistor film 4K is not limited to this.

[0064] [Wiring film formation step S15] Next, the wiring film 3K is formed as shown in Figure 16 and Figure 17. As shown in Figure 8, the wiring film forming step S15 includes a first film forming treatment S151 and a second film forming treatment S152.

[0065] In the first film formation process S151, as shown in FIG. 16, a first conductor film 301K is formed on the resistor film 4K. The first conductor film 301K is formed by, for example, a sputtering method. The first conductor film 301K is a thin film made of, for example, Ti. At this time, the first conductor film 301K covers substantially the entire surface of the resistor film 4K.

[0066] In the second film formation process S152, as shown in FIG. 17, a second conductor film 302K is formed on the first conductor film 301K. The second conductor film 302K is formed by, for example, plating or sputtering. The second conductor film 302K is made of, for example, Cu. At this time, the second conductor film 302K covers substantially the entire surface of the first conductor film 301K.

[0067] [Removal step S16] Next, the second conductor film 302K, the first conductor film 301K, and the resistor film 4K are each partially removed as appropriate, as shown in Fig. 18. As shown in Fig. 8, the removal step S16 includes a first partial removal process S161, a second partial removal process S162, and a third partial removal process S163.

[0068] In the first partial removal process S161, the second conductor film 302K is partially removed. In the second partial removal process S162, the first conductor film 301K is partially removed. In the third partial removal process S163, the resistor film 4K is partially removed. The first partial removal process S161, the second partial removal process S162, and the third partial removal process S163 are each performed by, for example, etching. The first partial removal process S161 forms the second conductor layer 302, the second partial removal process S162 forms the first conductor layer 301, and the third partial removal process S163 forms the resistor layer 4. The formed first conductor layer 301 and second conductor layer 302 constitute the wiring layer 3, and the wiring layer 3 has a common electrode 31, a plurality of individual electrodes 32, and a plurality of relay electrodes 33. The formed resistor layer 4 has a plurality of heat generating portions 41 and is divided into each of the heat generating portions 41. In this embodiment, the resistor film forming step S14 and the third partial removal process S163 correspond to a "resistor layer forming step" in the claims. Also, the wiring film forming step S15, the first partial removal process S161, and the second partial removal process S162 correspond to a "wiring layer forming step" in the claims.

[0069] [Protective layer formation step S17] Next, 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.

[0070] [Singulation process S181] Next, the substrate 10 is appropriately divided into individual head substrates 1. Note that if a substrate 10 corresponding to one head substrate 1 has been prepared in the substrate preparation step S11, the singulation step S181 does not need to be performed. The singulation step S181 is performed by, for example, laser cutting or dicing depending on the material of the substrate 10.

[0071] [Assembly process S182] Thereafter, the head substrate 1 and the connection substrate 5 are attached to the heat dissipation member 8, the driver IC 7 is mounted, the plurality of wires 61 and the plurality of wires 62 are bonded, and the protective resin 78 is formed.

[0072] As described above, the thermal printhead A1 shown in FIGS. 1 to 7 is manufactured through the steps shown in FIG.

[0073] The functions and effects of the thermal printhead A1 are as follows.

[0074] In the thermal printhead A1, the protrusions 13 have a flat first surface on which each of the multiple heat generating elements 41 is arranged. In the thermal printhead A1, this first surface is formed by a second inclined surface 142. The protrusions 13 also have a first curved convex surface 151 connected to the first surface. With this configuration, a curved surface (first curved convex surface 151) is arranged at the end of the first surface (second inclined surface 142) on which each heat generating element 41 is arranged. Therefore, the end of the first surface (second inclined surface 142) on which each heat generating element 41 is arranged has a rounded shape. In contrast to this configuration, if the end of the surface of the protrusions 13 on which each heat generating element 41 is arranged is angular (for example, as shown in FIG. 11 ), the friction load between the protective layer 2 and the printing medium 99 at the angular portion increases when the printing medium 99 is transported. This can cause wear on the protective layer 2 or the printing medium 99, resulting in the generation of foreign matter such as scrapings of the printing medium 99 (e.g., paper scraps) or scrapings of the surface layer of the thermal printhead. On the other hand, as described above, in the thermal printhead A1, the edges of the first surface (second inclined surface 142) on which each heat generating element 41 is disposed are rounded, thereby reducing the friction load between the protective layer 2 and the printing medium 99. This reduces wear on the protective layer 2 and the printing medium 99, and the generation of foreign matter. Therefore, the thermal printhead A1 can reduce the generation of foreign matter and the deterioration of print quality.

[0075] In the thermal printhead A1, the convex portion 13 further has a second curved convex surface 152. With this configuration, both ends of the first surface (second inclined surface 142) in the sub-scanning direction y are rounded. This configuration is advantageous for smooth passage of the print medium 99 and for suppressing the generation of foreign matter.

[0076] In the thermal printhead A1, each heat generating element 41 is arranged on a flat first surface (second inclined surface 142). With this configuration, the contact between the protective layer 2 on each heat generating element 41 and the print medium 99 is better than when each heat generating element 41 is arranged on a curved surface, and heat is transferred more efficiently to the print medium 99. Therefore, the thermal printhead A1 is preferable for improving print quality.

[0077] In the thermal printhead A1, the protrusions 13 have a first inclined surface 141 and a second inclined surface 142. With this configuration, the first inclined surface 141 and the second inclined surface 142, which are inclined in two stages relative to the main surface 11 (top surface 140), are aligned in the sub-scanning direction y. This makes it possible to reduce the angle between the top surface 140 and the first inclined surface 141, which is favorable for improving print quality. Furthermore, the smaller the angle between the top surface 140 and the first inclined surface 141, the more effectively the protective layer 2 is prevented from wearing down due to the passage of the print medium 99 during printing.

[0078] In the thermal printhead A1, the first surface is configured as the second inclined surface 142. That is, each heat generating element 41 is disposed on the second inclined surface 142. This configuration is preferable for making the thermal printer Pr a mechanism that transports the print medium 99 without bending it (a straight path mechanism).

[0079] In the thermal printhead A1, sub-heating units 35A and 35B are disposed at both ends of each heat-generating unit 41 in the sub-scanning direction y. When energized, the sub-heating units 35A and 35B have a lower temperature than each heat-generating unit 41 and a higher temperature than the portion where the second conductor layer 302 and the first conductor layer 301 are stacked. This allows for a more mitigated temperature gradient in the sub-scanning direction y compared to a case where the sub-heating units 35A and 35B are not provided. If the sub-heating units 35A and 35B were not provided, the portion where the second conductor layer 302 and the first conductor layer 301 are stacked would be adjacent to each heat-generating unit 41, increasing the temperature gradient. As a result, thermal stress due to the temperature difference at the boundary between these units could cause, for example, a break at the boundary. However, in the thermal printhead A1, as described above, the sub-heating units 35A and 35B mitigate the temperature gradient, thereby preventing damage due to thermal stress. Furthermore, in the thermal printhead A1, the print medium 99 is preheated by the sub-heating element 35A, which is located upstream of each heat-generating element 41 in the sub-scanning direction y, before being transported to each heat-generating element 41. This preheating by the sub-heating element 35A allows each heat-generating element 41 to produce color more quickly and clearly during printing. Therefore, the thermal printhead A1 can improve print quality and printing speed.

[0080] In the thermal printhead A1, the print medium 99 is transported in the sub-scanning direction y from the first curved convex surface 151 toward the first surface (second inclined surface 142). This configuration prevents the leading edge of the print medium 99 from colliding with the protective layer 2 on the convex portions 13 during transport. Such collisions with the convex portions 13 cause scraping debris from the protective layer 2. In particular, if the print medium 99 is harder than printing / information paper, such as a plastic card, the collision of the print medium 99 with the protective layer 2 on the convex portions 13 is likely to cause scraping debris from the protective layer 2. However, the thermal printhead A1 prevents the leading edge of the print medium 99 from colliding with the protective layer 2 on the convex portions 13, which is preferable in terms of preventing the generation of foreign matter.

[0081] In the manufacturing method of the thermal printhead A1, the substrate processing step S12 includes a second step S122. In the second step S122, an oxide film 131K is formed by thermally oxidizing the surface of the intermediate convex body 13K. This process causes the oxide film 131K to be formed in an arc shape at each of the corners 151K to 154K, 161K, and 162K during its growth. As a result, the first curved convex surface 151, the second curved convex surface 152, the third curved convex surface 153, and the fourth curved convex surface 154 are formed on the convex portion 13, and the first curved concave surface 161 and the second curved concave surface 162 can also be formed.

[0082] Another method for manufacturing a thermal printhead according to the present disclosure will now be described. For example, in the second step S122 of the substrate processing step S12, etching or blasting may be performed instead of forming and removing the oxide film 131K.

[0083] In the example where etching is performed in the second step S122, the etching may be either dry etching or wet etching. For example, in the second step S122 of this modification, etching is performed on at least the surface of the intermediate convex body 13K (the pair of primary inclined surfaces 141K, 143K and the pair of secondary inclined surfaces 142K, 144K). In this modification, not only the surface of the intermediate convex body 13K but also the main surface 11K is etched. That is, in this modification, etching is performed on the upper surface in the thickness direction z of the substrate 10K (see FIG. 11) after the first step S121. In dry etching, an etching gas such as a reactive ion gas or a plasma gas is irradiated onto the upper surface of the substrate 10K in the thickness direction z. In wet etching, the upper surface of the substrate 10K in the thickness direction z is exposed to an etching solvent such as fluoronitric acid. As a result, convex portions 13 (see FIG. 13) similar to those of the thermal printhead A1 are formed from the intermediate convex body 13K.

[0084] In the example where blasting is performed in the second step S122, the blasting may be either air shot blasting (sand blasting) or wet shot blasting (wet blasting). For example, in the second step S122 of this modification, as shown in FIG. 19, blasting is performed on at least the surface of the intermediate convex body 13K (the pair of primary inclined surfaces 141K, 143K and the pair of secondary inclined surfaces 142K, 144K). In this modification, not only the surface of the intermediate convex body 13K but also the main surface 11K is blasted. That is, in this modification, as shown in FIG. 19, blasting is performed on the upper surface in the thickness direction z of the substrate 10K (see FIG. 11) after the first step S121. In sandblasting, fine granular abrasive is sprayed by compressed air onto the upper surface of the substrate 10K in the thickness direction z. In wet blasting, a mixture of fine granular abrasive and water is sprayed by compressed air onto the upper surface of the substrate 10K in the thickness direction z. As a result, the intermediate convex body 13K is formed into a convex portion 13 (see FIG. 13) similar to that of the thermal printhead A1.

[0085] When etching or blasting is performed in second step S122, the curvature of the first curved convex surface 151 of the convex portion 13 may become smaller than the curvature of the second curved convex surface 152, as shown in FIG. 20 . In other words, the radius of curvature of the first curved convex surface 151 may become larger than the radius of curvature of the second curved convex surface 152. Similarly, the curvature of the third curved convex surface 153 may become smaller than the curvature of the fourth curved convex surface 154. In other words, the radius of curvature of the third curved convex surface 153 may become larger than the radius of curvature of the fourth curved convex surface 154. In a thermal printhead having convex portions 13 with the shape shown in FIG. 20 , the generation of foreign matter and the deterioration of print quality can be suppressed, just like in thermal printhead A1. Furthermore, in the thermal printhead according to this modification, the first curved convex surface 151 is more gently curved than the first curved convex surface 151 of the thermal printhead A1, which is preferable in terms of suppressing the generation of foreign matter.

[0086] Next, another configuration example of the thermal printhead A1 of the present disclosure will be described.

[0087] In the thermal printhead A1, an example was shown in which multiple heat generating elements 41 were arranged on the second inclined surface 142, but instead of this configuration, each heat generating element 41 may be formed on the top surface 140, as shown in Fig. 21. In a thermal printhead in which the convex portions 13 have the shape shown in Fig. 21, the generation of foreign matter is also suppressed, and degradation of print quality can be suppressed, just like in the thermal printhead A1.

[0088] In the thermal printhead A1, the convex portion 13 has a second inclined surface 142 and a fourth inclined surface 144, but as shown in FIG. 22, it may not have these. The convex portion 13 shown in FIG. 22 has a top surface 140, a first inclined surface 141, a third inclined surface 143, a first curved convex surface 155, a second curved convex surface 156, a first curved concave surface 161, and a second curved concave surface 162. The first curved convex surface 155 is located between the first inclined surface 141 and the top surface 140 in the sub-scanning direction y. The second curved convex surface 156 is located between the third inclined surface 143 and the top surface 140 in the sub-scanning direction y. The curvature of the first curved convex surface 155 and the second curved convex surface 156 are approximately the same. The protrusions 13 shown in Fig. 22 are formed, for example, by performing only the first etching without performing the second etching in the first step S121 of the substrate processing step S12. In a thermal printhead having protrusions 13 of the shape shown in Fig. 22, the generation of foreign matter is suppressed, and degradation of print quality can be suppressed, just as in the thermal printhead A1.

[0089] In the thermal printhead A1, the shape of the heat dissipation member 8 is not limited to the example shown in FIG. 4, and for example, the first support surface 81 may be inclined relative to the second support surface 82, as shown in FIG.

[0090] In the thermal printhead A1, the head substrate 1 is shown as being made of a single crystal semiconductor, but is not limited to this and may be made of ceramic.

[0091] 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 in the thermal printhead manufacturing method, can be freely designed and modified in various ways. For example, the thermal printhead, thermal printer, and thermal printhead manufacturing method according to the present disclosure include the following embodiments: [Appendix 1] a substrate 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 that forms current paths to the plurality of heat generating portions and is supported by the substrate; Equipped with the substrate includes a protrusion protruding from the main surface and extending in a main scanning direction; The convex portion of the thermal printhead has a flat first surface on which each of the plurality of heat generating elements is arranged, and a first curved convex surface connected to the first surface. [Appendix 2] the protrusion has a top surface parallel to the main surface and a first inclined surface inclined with respect to the main surface, 2. The thermal printhead according to claim 1, wherein the first inclined surface is located between the main surface and the top surface in the sub-scanning direction. [Appendix 3] the protrusion has a second inclined surface inclined with respect to the main surface, the second inclined surface is located between the top surface and the first inclined surface in the sub-scanning direction, 3. The thermal printhead according to claim 2, wherein the second inclined surface has an inclination angle with respect to the main surface that is smaller than the inclination angle of the first inclined surface with respect to the main surface. [Appendix 4] 4. The thermal printhead of claim 3, wherein the second inclined surface constitutes the first surface. [Appendix 5] the convex portion has a second curved convex surface connected to the first surface, the first curved convex surface is interposed between the first surface and the first inclined surface in the sub-scanning direction, 5. The thermal printhead according to claim 4, wherein the second curved convex surface is interposed between the first surface and the top surface in the sub-scanning direction. [Appendix 6] 6. The thermal printhead of claim 5, wherein the first curved convex surface has a smaller curvature than the second curved convex surface. [Appendix 7] the protrusion has a third inclined surface and a fourth inclined surface disposed away from the first surface by the top surface, the fourth inclined surface is located between the top surface and the third inclined surface in the sub-scanning direction, 7. The thermal printhead according to claim 5, wherein the fourth inclined surface has an inclination angle with respect to the main surface that is smaller than the inclination angle of the third inclined surface with respect to the main surface. [Appendix 8] the convex portion has a third curved convex surface and a fourth curved convex surface, each of which is connected to the fourth inclined surface; the third curved convex surface is interposed between the top surface and the fourth inclined surface in the sub-scanning direction, 8. The thermal printhead according to claim 7, wherein the fourth curved convex surface is interposed between the fourth inclined surface and the third inclined surface in the sub-scanning direction. [Appendix 9] 4. The thermal printhead of claim 2, wherein the top surface constitutes the first surface. [Appendix 10] 10. The thermal printhead according to claim 2, wherein the convex portion has a curved concave surface located between the main surface and the first inclined surface in the sub-scanning direction. [Appendix 11] 11. The thermal printhead according to claim 1, wherein the substrate is made of a single crystal semiconductor. [Appendix 12] A thermal printhead according to any one of Supplementary Note 1 to Supplementary Note 11; a platen facing the thermal printhead and transporting the print medium in the sub-scanning direction. [Appendix 13] 13. The thermal printer of claim 12, wherein the print medium is transported in the sub-scanning direction from the first curved convex surface toward the first surface. [Appendix 14] 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; and the protrusion has a flat first surface on which each of the plurality of heat generating portions is arranged, and a first curved convex surface connected to the first surface, The method for manufacturing a thermal printhead, wherein the substrate processing process includes a first process of forming an intermediate convex body having the first surface and protruding from the main surface, and a second process of forming the first curved convex surface on the intermediate convex body. [Appendix 15] 15. The method for manufacturing a thermal printhead according to claim 14, wherein in the second step, an oxide film is formed on at least the surface of the intermediate convex body, and then the oxide film is removed. [Appendix 16] 15. The method for manufacturing a thermal printhead according to claim 14, wherein in the second step, etching is performed on at least the surface of the intermediate convex body. [Appendix 17] 15. The method for manufacturing a thermal printhead according to claim 14, wherein in the second step, at least the surface of the intermediate convex body is subjected to shot blasting. [Appendix 18] 18. The method for manufacturing a thermal printhead according to claim 17, wherein the shot blasting is wet blasting. [Explanation of symbols]

[0092] Pr: Thermal printer A1: Thermal printhead 1: Head board 10,10K: Substrate 11,11K: Main surface 12,12K: Back side 13: Convex part 13K: Intermediate convex body 131K: oxide film 140:Top surface 140K:Top surface 141: 1st slope 142:Second slope 143:Third slope 144: 4th slope 141K,143K: Primary slope 142K,144K: Secondary slope 151: First curved convex surface 152: Second curved convex surface 153: Third curved convex surface 154: 4th curved convex surface 155: First curved convex surface 156: Second curved convex surface 151K,152K,153K,154K: Corner 161: First curved concave surface 162: Second curved concave surface 19: Insulating layer 2:Protective layer 21: Pad opening 3: Wiring layer 3K: Wiring film 301: First conductor layer 301K: First conductive film 302: Second conductor layer 302K: Second conductive film 31: Common electrode 311:Direct part 312: Branch 313: Belt 314 :Connection part 32: Individual electrode 321: Belt 322: Pad section 33: Relay electrode 331: Belt 332 :Connection part 35A: Sub-heating section 35B: Sub-heating section 4:Resistor layer 4K:Resistor film 41: Heat generating part 5: Connection board 51: Main surface 52: Back side 55: Control electrode 59: Connector 61: Wire 62: Wire 7: Driver IC 71: Output pad 72: Input pad 78: Protective resin 8: Heat dissipation material 81: 1st support surface 82:Second support surface 91: Platen roller 99:Print media

Claims

1. a substrate 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 that forms current paths to the plurality of heat generating portions and is supported by the substrate; Equipped with the substrate includes a protrusion protruding from the main surface and extending in a main scanning direction; the protrusion has a flat first surface on which each of the plurality of heat generating portions is arranged, and a first curved convex surface connected to the first surface, the wiring layer includes a first conductor layer and a second conductor layer stacked in the thickness direction, and has a sub-heating portion having a resistance value per unit length in the sub-scanning direction lower than each of the plurality of heat-generating portions; the first conductor layer is formed on the resistor layer, the second conductor layer is formed on the first conductor layer and partially covers the first conductor layer; the sub-heating portion is a portion of the first conductor layer that is exposed from the second conductor layer, the protrusion has a top surface parallel to the main surface, a first inclined surface inclined with respect to the main surface, and a second inclined surface inclined with respect to the main surface, the first inclined surface is located between the main surface and the top surface in the sub-scanning direction, the second inclined surface is located between the top surface and the first inclined surface in the sub-scanning direction, an inclination angle of the second inclined surface with respect to the main surface is smaller than an inclination angle of the first inclined surface with respect to the main surface; the second inclined surface constitutes the first surface, each of the first conductor layer and the second conductor layer being partially formed on the top surface; Thermal print head.

2. each of the first conductor layer and the second conductor layer is partially formed on the first inclined surface; 2. The thermal printhead of claim 1.

3. the convex portion has a second curved convex surface connected to the first surface, the first curved convex surface is interposed between the first surface and the first inclined surface in the sub-scanning direction, the second curved convex surface is interposed between the first surface and the top surface in the sub-scanning direction; 3. The thermal printhead according to claim 1.

4. the first curved convex surface has a smaller curvature than the second curved convex surface; 4. The thermal printhead according to claim 3.

5. the protrusion has a third inclined surface and a fourth inclined surface disposed away from the first surface via the top surface, the fourth inclined surface is located between the top surface and the third inclined surface in the sub-scanning direction, an inclination angle of the fourth inclined surface with respect to the main surface being smaller than an inclination angle of the third inclined surface with respect to the main surface; 5. The thermal printhead according to claim 3 or 4.

6. the convex portion has a third curved convex surface and a fourth curved convex surface, each of which is connected to the fourth inclined surface; the third curved convex surface is interposed between the top surface and the fourth inclined surface in the sub-scanning direction, the fourth curved convex surface is interposed between the fourth inclined surface and the third inclined surface in the sub-scanning direction; 6. The thermal printhead according to claim 5.

7. the convex portion has a curved concave surface located between the main surface and the first inclined surface in the sub-scanning direction; 7. The thermal printhead according to claim 1.

8. the wiring layer has a common electrode, a plurality of individual electrodes each having an opposite polarity to the common electrode, and a plurality of relay electrodes electrically connected between the common electrode and the plurality of individual electrodes, the sub-heating portion includes a first sub-heating portion located on the side of the relay electrodes with respect to the plurality of heat generating portions in the sub-scanning direction, and a second sub-heating portion located on the side of the common electrode and the plurality of individual electrodes with respect to the plurality of heat generating portions in the sub-scanning direction, an area of ​​the first sub-heating portion as viewed in the thickness direction is smaller than an area of ​​the second sub-heating portion as viewed in the thickness direction; 8. The thermal printhead according to claim 1.

9. The substrate is made of a single crystal semiconductor.

9. The thermal printhead according to claim 1.

10. A thermal printhead according to any one of claims 1 to 9; a platen facing the thermal printhead and transporting the print medium in the sub-scanning direction.

11. the print medium is transported in a sub-scanning direction from the first curved convex surface toward the first surface; The thermal printer according to claim 10.

12. 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; and the protrusion has a flat first surface on which each of the plurality of heat generating portions is arranged, and a first curved convex surface connected to the first surface, the substrate processing step includes a first step of forming an intermediate convex body having the first surface and protruding from the main surface, and a second step of forming the first curved convex surface on the intermediate convex body, In the second step, an oxide film is formed on at least the surface of the intermediate convex body, and then the oxide film is removed. A method for manufacturing a thermal printhead.

13. In the second step, at least the surface of the intermediate convex body is subjected to etching or shot blasting. The method for manufacturing a thermal printhead according to claim 12.

14. In the second step, the shot blasting is performed, The shot blasting is a wet blasting. The method for manufacturing a thermal printhead according to claim 13.

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