Thermal printhead and method for manufacturing the same

Abstract

A thermal print head comprises: a semiconductor substrate that has a main surface and a reverse surface separated from each other in the thickness direction, a first through section being formed passing from the main surface to the reverse surface; a resistor layer that includes a plurality of heat-emitting parts arrayed in a main scanning direction, the resistor layer being formed on the main surface; a first electrode formed on the reverse surface; a wiring layer that is formed on the resistor layer and is electrically connected to the plurality of heat-emitting parts; and first through wiring accommodated in the first through section. The wiring layer includes common wiring positioned on a first side in an auxiliary scanning direction in relation to the plurality of heat-emitting parts. The first through wiring is connected to the common wiring and to the first electrode.

Description

[Technical field]

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

[0002] Patent Documents 1 and 2 disclose examples of conventional thermal printheads. The thermal printhead disclosed in Patent Document 1 includes a plurality of heat generating portions formed on a substrate and arranged along the main scanning direction. These heat generating portions are composed of a resistor layer formed on the substrate and a wiring layer partially overlapping the resistor layer. Each heat generating portion is a part of the resistor layer exposed from the wiring layer. When a current flows through the wiring layer under control, one or more selected heat generating portions generate heat.

[0003] In the thermal printhead described in Patent Document 1, silicon is selected as the material of the substrate. The resistor layer and the wiring layer are formed by utilizing a semiconductor process. Meanwhile, the wiring layer includes a common wiring and a plurality of individual wirings. In the substrate, the common wiring and the plurality of individual wirings are arranged on both sides of the plurality of heat generating parts in the sub-scanning direction. Here, in order to improve the printing quality, measures may be taken to increase the number of the plurality of individual wirings arranged, increase the number of the plurality of heat generating parts arranged, and reduce the width (length in the main scanning direction) of each of the plurality of heat generating parts. This makes it possible to perform more minute printing on the recording medium. However, in this case, there may be a shortage of space on the substrate for arranging the common wiring. When the space is insufficient, it is necessary to make the substrate larger. Making the substrate larger leads to a deterioration in the manufacturing efficiency of the thermal printhead, so improvement in this respect is desired. In addition, improvement is also desired for the thermal printhead described in Patent Document 2 so that it can be made smaller depending on the application. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-7203 A [Patent Document 2] JP 2019-166824 A Summary of the Invention [Problem to be solved by the invention]

[0005] In view of the above circumstances, an object of a first aspect of the present disclosure is to provide a thermal printhead capable of finer printing without increasing the size of a substrate, and a method for manufacturing the same. [Means for solving the problem]

[0006] According to one embodiment of a first aspect of the present disclosure, there is provided a thermal printhead. The thermal printhead includes a semiconductor substrate having a main surface and a back surface spaced apart from each other in a thickness direction and having a first through portion formed therein penetrating from the main surface to the back surface, a resistor layer including a plurality of heat generating portions arranged in a main scanning direction and formed on the main surface, a first electrode formed on the back surface, a wiring layer formed on the resistor layer and conducting to the plurality of heat generating portions, and a first through wiring housed in the first through portion. The wiring layer includes a common wiring located on a first side in a sub-scanning direction with respect to the plurality of heat generating portions. The first through wiring is connected to the common wiring and the first electrode.

[0007] Preferably, the thermal printhead further includes a plurality of second electrodes and a plurality of second through wirings formed on the rear surface. The wiring layer includes a plurality of individual wirings located on a second side in the sub-scanning direction with respect to the plurality of heat generating portions. The semiconductor substrate is formed with a plurality of second through portions that penetrate from the main surface to the rear surface and are located on the opposite side of the plurality of heat generating portions in the sub-scanning direction from the first through portions. The plurality of second through wirings are individually housed in the plurality of second through portions. Each of the plurality of second through wirings is connected to one of the plurality of individual wirings and one of the plurality of second electrodes.

[0008] Preferably, the main surface includes a base surface and a convex surface that bulges from the base surface in the thickness direction, the convex surface extends along the main scanning direction, and the multiple heat generating portions are formed on the convex surface.

[0009] Preferably, the convex surface includes a top surface parallel to the base surface and a pair of inclined surfaces connected to the top surface and the base surface and positioned apart from each other in the sub-scanning direction, and the multiple heat generating portions are formed on the top surface.

[0010] Preferably, a portion of the common wiring and a portion of each of the plurality of individual wirings are formed on one of the pair of inclined surfaces.

[0011] Preferably, the pair of inclined surfaces are inclined with respect to the base surface so as to approach each other from the base surface to the top surface.

[0012] Preferably, each of the pair of inclined surfaces includes a first region connected to the base surface and a second region connected to the top surface and the first region, and an inclination angle of the second region relative to the base surface is smaller than an inclination angle of the first region relative to the base surface.

[0013] Preferably, the semiconductor substrate comprises a single crystal material of silicon.

[0014] Preferably, the thermal printhead further comprises a first insulating layer covering the main surface, the resistor layer being in contact with the first insulating layer.

[0015] Preferably, the semiconductor substrate has a first inner surface connected to the main surface and the back surface and defining the first penetrating portion, and a plurality of second inner surfaces connected to the main surface and the back surface and defining each of the plurality of second penetrating portions, and the first insulating layer covers the first inner surface and the plurality of second inner surfaces.

[0016] Preferably, the thermal printhead further includes a second insulating layer covering the rear surface and connected to the first insulating layer, and the first electrode and the plurality of second electrodes are in contact with the second insulating layer.

[0017] Preferably, the thermal printhead further includes a heat dissipation layer located between the first electrode and the multiple second electrodes in the sub-scanning direction and formed in contact with the second insulating layer, and when viewed along the thickness direction, the heat dissipation layer overlaps the multiple heat generating portions.

[0018] Preferably, the thermal printhead further includes a wiring board facing the rear surface and having the first electrode and a plurality of second electrodes bonded thereto, the wiring board having a heat sink to which the heat dissipation layer is bonded.

[0019] Preferably, the thermal printhead further comprises a protective layer covering a part of the main surface, the plurality of heat generating portions, and the wiring layer.

[0020] According to another embodiment of the first aspect of the present disclosure, there is provided a method for manufacturing a thermal printhead. The method includes the steps of forming a first recess in a substrate having a main surface facing a thickness direction and made of a semiconductor material, the first recess being recessed in the thickness direction from the main surface, forming a resistor layer including a plurality of heat generating portions arranged in a main scanning direction on the main surface and in the first recess, forming a wiring layer on the resistor layer that is conductive to the plurality of heat generating portions, removing a portion of the substrate located on the opposite side of the main surface in the thickness direction, and forming an electrode on the substrate that is located on the opposite side of the substrate from the wiring layer in the thickness direction and conductive to the wiring layer. The step of forming the wiring layer includes the steps of forming a common wiring located on a first side of the plurality of heat generating portions in the sub-scanning direction, and a first through wiring that is accommodated in the first recess and connected to the common wiring. The step of removing a portion of the substrate includes removing the portion of the substrate until a portion of the first through wiring is exposed from the substrate. The step of forming the electrode includes a step of forming a first electrode that is electrically connected to the common wiring, the step of forming the first electrode includes forming the first electrode so as to be in contact with the first through wiring.

[0021] Preferably, the manufacturing method further includes, between the step of forming the first recess and the step of forming the resistor layer, a step of forming a plurality of second recesses recessed from the main surface in the thickness direction of the base material and located on the opposite side of the first recesses with respect to the plurality of heat generating parts in the sub-scanning direction. In the step of forming the resistor layer, a part of the resistor layer is formed in the plurality of second recesses. The step of forming the wiring layer includes a step of forming a plurality of individual wirings located on a second side of the plurality of heat generating parts in the sub-scanning direction, and a plurality of second through wirings individually accommodated in the plurality of second recesses and individually connected to the plurality of individual wirings. In the step of removing a part of the base material, the part of the base material is removed until a part of the plurality of second through wirings is exposed from the base material. The step of forming the electrode includes a step of forming a plurality of second electrodes individually conducting to the plurality of individual wirings. In the step of forming the plurality of second electrodes, the plurality of second electrodes are formed so that the plurality of second electrodes are individually in contact with the plurality of second through wirings.

[0022] Preferably, the main surface includes a base surface and a convex surface that bulges from the base surface in the thickness direction. The manufacturing method further includes, before the step of forming the first recess, a step of forming a convex portion on the base material, the convex portion bulging from the base surface in the thickness direction and extending along the main scanning direction and including the convex surface. In the step of forming the resistor layer, the plurality of heat generating portions are formed on the convex surface.

[0023] Preferably, the semiconductor material comprises a single crystal material of silicon. Effect of the Invention

[0024] The thermal printhead and method of manufacturing the same according to the present disclosure enable finer printing without increasing the size of the substrate.

[0025] Other features and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 is a plan view of a thermal printhead according to a first embodiment of a first aspect of the present disclosure. [Diagram 2] FIG. 2 is a plan view of a main part of the thermal printhead shown in FIG. [Diagram 3] FIG. 3 is a partially enlarged view of FIG. [Figure 4] FIG. 3 is a partially enlarged view of FIG. [Diagram 5] FIG. 2 is a bottom view of the main part of the thermal printhead shown in FIG. [Figure 6] FIG. 2 is a cross-sectional view taken along line 006-006 in FIG. [Figure 7] 2 is a cross-sectional view of a main part of the thermal printhead shown in FIG. [Figure 8] FIG. 8 is a partially enlarged view of FIG. [Figure 9] FIG. 8 is a partially enlarged view of FIG. [Figure 10] FIG. 8 is a partially enlarged view of FIG. [Figure 11] FIG. 2 is a cross-sectional view taken along line 011-011 in FIG. [Figure 12] FIG. 2 is a cross-sectional view taken along line 012-012 in FIG. [Figure 13] 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. [Figure 14] 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. [Figure 15] 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. [Figure 16] 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. [Figure 17] 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. [Figure 18] 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. [Figure 19]2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. [Figure 20] 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. [Figure 21] 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. [Figure 22] 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. [Figure 23] 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. [Figure 24] 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. [Diagram 25] 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. [Figure 26] 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. [Figure 27] 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. [Figure 28] 2A to 2C are partially enlarged cross-sectional views illustrating the manufacturing process of the main part of the thermal printhead shown in FIG. [Figure 29] 2A to 2C are partially enlarged cross-sectional views illustrating the manufacturing process of the main part of the thermal printhead shown in FIG. [Diagram 30] 2A to 2C are partially enlarged cross-sectional views illustrating the manufacturing process of the main part of the thermal printhead shown in FIG. [Diagram 31] 2A to 2C are partially enlarged cross-sectional views illustrating the manufacturing process of the main part of the thermal printhead shown in FIG. [Diagram 32] 2A to 2C are partially enlarged cross-sectional views illustrating the manufacturing process of the main part of the thermal printhead shown in FIG. [Diagram 33] 2A to 2C are cross-sectional views illustrating a manufacturing process for the main part of the thermal printhead shown in FIG. [Diagram 34] 4 is a cross-sectional view of a main part of a thermal printhead according to a second embodiment of the first aspect of the present disclosure. FIG. [Diagram 35] FIG. 35 is a partially enlarged view of FIG. [Diagram 36] FIG. 2 is a plan view showing a thermal printhead according to an embodiment of a second aspect of the present disclosure. [Figure 37] A cross-sectional view taken along line 037-037 in Figure 36. [Figure 38] FIG. 38 is a partially enlarged view of FIG. [Figure 39] FIG. 37 is an enlarged plan view of a main portion of the thermal printhead shown in FIG. 36. [Diagram 40] 37 is a cross-sectional view showing a step of an example of a method for manufacturing the thermal printhead shown in FIG. 36. [Diagram 41] FIG. 41 is a cross-sectional view showing a step following FIG. 40. [Diagram 42] FIG. 42 is a cross-sectional view showing a step following FIG. 41. [Diagram 43] FIG. 43 is a cross-sectional view showing a step following FIG. 42. [Diagram 44] FIG. 44 is a cross-sectional view showing a step following FIG. 43. [Diagram 45] FIG. 45 is a cross-sectional view showing a step following FIG. 44. [Diagram 46] FIG. 46 is a plan view showing a step following that shown in FIG. 45. [Figure 47] FIG. 47 is a partially enlarged view of FIG. 46. [Figure 48] FIG. 48 is a partially enlarged view of FIG. 47. [Figure 49] FIG. 47 is a schematic plan view showing a step following FIG. 46. [Figure 50] FIG. 50 is a schematic plan view showing a step following FIG. 49. [Figure 51] FIG. 51 is a schematic plan view showing a step following FIG. 50. [Figure 52] FIG. 52 is a schematic plan view showing a step following FIG. 51. [Figure 53] 37 is a plan view showing a case where the substrate is composed of a large number of individual chips, as compared with the thermal printhead shown in FIG. 36. [Figure 54] 37 is a plan view showing a case where the substrate is composed of a smaller number of individual chips compared to the thermal printhead shown in FIG. 36. [Figure 55] FIG. 11 is a plan view showing a modified example of a thermal printhead according to the second aspect of the present disclosure. [Figure 56] A cross-sectional view taken along line 056-056 in Figure 55. [Figure 57] 1 is a plan view of a thermal printhead according to a first embodiment of a third aspect of the present disclosure, seen through a protective layer. [Figure 58] FIG. 58 is a plan view of the essential parts of the thermal printhead shown in FIG. 57, seen through the protective layer. [Figure 59] FIG. 58 is a partially enlarged view of FIG. [Figure 60] A cross-sectional view taken along line 060-060 in Figure 57. [Figure 61] FIG. 58 is a cross-sectional view of a main part of the thermal printhead shown in FIG. 57. [Figure 62] FIG. 62 is a partially enlarged view of FIG. 61. [Figure 63] FIG. 58 is a partially enlarged view of FIG. 57, showing the insulating layer, the resistor layer, the wiring layer, the first substrate, the second substrate, and a plurality of second interconnects. [Figure 64] This is a cross-sectional view taken along line 064-064 in Figure 63. [Figure 65] 65 is a cross-sectional view taken along line 065-065 in FIG. 63, showing only the substrate and the first interconnect wiring. [Figure 66] FIG. 65 is a partially enlarged view of FIG. [Figure 67] FIG. 58 is a cross-sectional view showing a modification of the thermal printhead shown in FIG. 57, illustrating only the base material and the first interconnection wiring. [Figure 68] FIG. 58 is a cross-sectional view showing a modification of the thermal printhead shown in FIG. 57, illustrating only the base material and the first interconnection wiring. [Figure 69] 58A to 58C are cross-sectional views illustrating the manufacturing process for the main part of the thermal printhead shown in FIG. 57. [Figure 70] 58A to 58C are cross-sectional views illustrating the manufacturing process for the main part of the thermal printhead shown in FIG. 57. [Figure 71]58A to 58C are cross-sectional views illustrating the manufacturing process for the main part of the thermal printhead shown in FIG. 57. [Figure 72] 58A to 58C are cross-sectional views illustrating the manufacturing process for the main part of the thermal printhead shown in FIG. 57. [Figure 73] 58 is a partially enlarged plan view illustrating the manufacturing process of the main part of the thermal printhead shown in FIG. 57. [Figure 74] 58A to 58C are cross-sectional views illustrating the manufacturing process for the main part of the thermal printhead shown in FIG. 57. [Figure 75] 58A to 58C are cross-sectional views illustrating the manufacturing process for the main part of the thermal printhead shown in FIG. 57. [Figure 76] 58A to 58C are cross-sectional views illustrating the manufacturing process for the main part of the thermal printhead shown in FIG. 57. [Figure 77] 58A to 58C are cross-sectional views illustrating the manufacturing process for the main part of the thermal printhead shown in FIG. 57. [Figure 78] 58A to 58C are cross-sectional views illustrating the manufacturing process for the main part of the thermal printhead shown in FIG. 57. [Figure 79] 58A to 58C are cross-sectional views illustrating the manufacturing process for the main part of the thermal printhead shown in FIG. 57. [Figure 80] 58A to 58C are cross-sectional views illustrating the manufacturing process for the main part of the thermal printhead shown in FIG. 57. [Figure 81] 11 is a plan view of a thermal printhead according to a second embodiment of the third aspect of the present disclosure, seen through a protective layer. FIG. [Figure 82] FIG. 11 is a plan view of a thermal printhead according to a third embodiment of the third aspect of the present disclosure, seen through a protective layer. [Figure 83] FIG. 58 is a partially enlarged view of FIG. 57, showing the insulating layer, the resistor layer, the wiring layer (excluding a part of the common wiring), and a plurality of second interconnects. [Figure 84] 13 is a cross-sectional view of a main part of a thermal printhead according to a fourth embodiment of the third aspect of the present disclosure. FIG. [Figure 85] FIG. 85 is a partially enlarged view of FIG. 84. [Figure 86]13 is a cross-sectional view of a main part of a thermal printhead according to a fifth embodiment of the third aspect of the present disclosure. FIG. [Figure 87] FIG. 87 is a partially enlarged view of FIG. 86. [Figure 88] 87A to 87C are cross-sectional views illustrating the manufacturing process for the main part of the thermal printhead shown in FIG. 86. [Figure 89] 1 is a plan view of a thermal printhead according to a first embodiment of a fourth aspect of the present disclosure, showing a protective layer and a covering layer. [Figure 90] FIG. 89 is a plan view of the main part of the thermal printhead shown in FIG. 89, showing the protective layer and the covering layer. [Figure 91] FIG. 91 is a partially enlarged view of FIG. 90. [Figure 92] A cross-sectional view taken along line 092-092 in Figure 89. [Figure 93] FIG. 89 is a cross-sectional view of a main part of the thermal printhead shown in FIG. [Figure 94] FIG. 94 is a partially enlarged view of FIG. 93. [Figure 95] 89A to 89C are cross-sectional views illustrating the manufacturing process for the main part of the thermal printhead shown in FIG. [Figure 96] 89A to 89C are cross-sectional views illustrating the manufacturing process for the main part of the thermal printhead shown in FIG. [Figure 97] 89A to 89C are cross-sectional views illustrating the manufacturing process for the main part of the thermal printhead shown in FIG. [Figure 98] 89A to 89C are cross-sectional views illustrating the manufacturing process for the main part of the thermal printhead shown in FIG. [Figure 99] 89A to 89C are cross-sectional views illustrating the manufacturing process for the main part of the thermal printhead shown in FIG. [Figure 100] 89A to 89C are cross-sectional views illustrating the manufacturing process for the main part of the thermal printhead shown in FIG. [Figure 101] 89A to 89C are cross-sectional views illustrating the manufacturing process for the main part of the thermal printhead shown in FIG. [Figure 102] 89A to 89C are cross-sectional views illustrating the manufacturing process for the main part of the thermal printhead shown in FIG. [Figure 103] 89A to 89C are cross-sectional views illustrating the manufacturing process for the main part of the thermal printhead shown in FIG. [Figure 104] FIG. 89 is a partially enlarged cross-sectional view of a modified example of the thermal printhead shown in FIG. [Figure 105] FIG. 89 is a cross-sectional view illustrating a modified example of the manufacturing process for the main part of the thermal printhead shown in FIG. [Fig. 106] 11 is a plan view of a thermal printhead according to a second embodiment of the fourth aspect of the present disclosure, showing a protective layer and a covering layer. FIG. [Figure 107] A plan view of the main part of the thermal printhead shown in Figure 106, showing the protective layer and the covering layer. [Figure 108] FIG. 107 is a partially enlarged view. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Various embodiments for carrying out the present disclosure will be described with reference to the accompanying drawings. Among Figs. 1 to 108, Figs. 1 to 35 are explanatory diagrams of a first aspect of the present disclosure. Similarly, Figs. 36 to 56 are explanatory diagrams of a second aspect of the present disclosure, Figs. 57 to 88 are explanatory diagrams of a third aspect of the present disclosure, and Figs. 89 to 108 are explanatory diagrams of a fourth aspect of the present disclosure.

[0028] First, a thermal printhead A10 according to a first embodiment of the first aspect will be described with reference to FIGS. 1 to 12. The thermal printhead A10 is a main unit of a thermal printer. The thermal printhead A10 mainly includes a substrate 1, a first insulating layer 21, a second insulating layer 22, a resistor layer 3, a wiring layer 4, a first through-wire 511, a plurality of second through-wires 512, a first electrode 521, a plurality of second electrodes 522, a heat dissipation layer 53, and a protective layer 6. In addition to these, the thermal printhead A10 includes a wiring substrate 71, a heat sink 72, a plurality of driving elements 73, a plurality of first wires 74, a plurality of second wires 75, a sealing resin 76, and a connector 77. Here, in FIG. 1, the protective layer 6, the plurality of first wires 74, the plurality of second wires 75, and the sealing resin 76 are omitted. In FIGS. 2 to 4, the protective layer 6 is omitted.

[0029] In this disclosure, the main scanning direction of the thermal printhead A10 is referred to as the "x direction" and the sub-scanning direction (orthogonal to the main scanning direction) is referred to as the "y direction" as appropriate. The direction extending through the thickness of the substrate 1 is referred to as the "z direction". The z direction is orthogonal to both the x direction and the y direction. In the following description, "when viewed in (along) the z direction" and "when viewed in (along) the thickness direction" have the same meaning, and may be referred to as "in a plan view".

[0030] As shown in FIG. 6, in the thermal printhead A10, the main part of the thermal printhead A10 including the substrate 1 is bonded to a wiring substrate 71. The wiring substrate 71 is bonded to a heat sink 72. The wiring substrate 71 is sandwiched between the main part of the thermal printhead A10 and the heat sink 72 in the z direction. On the substrate 1, a plurality of heat generating parts 31 (described later) that form a part of the resistor layer 3 and are arranged in the x direction are formed. The plurality of heat generating parts 31 selectively generate heat by a plurality of drive elements 73 mounted on the wiring substrate 71. The plurality of drive elements 73 are driven according to a print signal transmitted from the outside via a connector 77. As shown in FIG. 6, a platen roller 79 that constitutes a thermal printer presses a recording medium 78 such as thermal paper against the plurality of heat generating parts 31, whereby the plurality of heat generating parts 31 print on the recording medium 78. For convenience of explanation, the side of the supply source of the recording medium 78 in FIG. 6 (the right side in FIG. 6) is called the "upstream side." In FIG. 6, the side to which the recording medium 78 is discharged (the left side in FIG. 6) is referred to as the "downstream side."

[0031] 1, the substrate 1 has a strip shape extending in the x direction when viewed along the z direction. The substrate 1 is made of a semiconductor material. The semiconductor material includes a single crystal material of silicon (Si).

[0032] As shown in FIG. 6, the substrate 1 has a main surface 10 and a back surface 13. The main surface 10 and the back surface 13 of the substrate 1 are both surfaces with Miller indices (100). The main surface 10 and the back surface 13 face opposite each other in the z direction. In the thermal printhead A10, the main surface 10 faces the platen roller 79 shown in FIG. 6, and the back surface 13 faces the wiring board 71. As shown in FIG. 7, the main surface 10 includes a base surface 11 and a convex surface 12. The base surface 11 is parallel to the back surface 13. The convex surface 12 bulges out from the base surface 11 in the z direction. The convex surface 12 extends along the x direction.

[0033] As shown in FIG. 8, the convex surface 12 has a top surface 121 and a pair of inclined surfaces 122. The top surface 121 is located away from the base surface 11 in the z direction and is parallel to the base surface 11. The pair of inclined surfaces 122 are located away from each other in the y direction. The pair of inclined surfaces 122 are connected to the top surface 121 and the base surface 11. The pair of inclined surfaces 122 are inclined with respect to the base surface 11 so as to approach each other from the base surface 11 to the top surface 121. The inclination angle α of each of the pair of inclined surfaces 122 with respect to the base surface 11 is the same.

[0034] As shown in FIG. 7, the substrate 1 is formed with a convex portion 17, a first through portion 18, and a plurality of second through portions 19. The convex portion 17 bulges from the base surface 11 in the z direction and extends along the x direction. The convex surface 12 is the surface of the convex portion 17. Therefore, the configuration of the convex surface 12 is based on the shape of the convex portion 17. The first through portion 18 is located on one side (downstream side) of the convex portion 17 in the y direction. The plurality of second through portions 19 are located on the other side (upstream side) of the convex portion 17 in the y direction. That is, the plurality of second through portions 19 are located on the opposite side of the first through portion 18 with respect to the plurality of heat generating portions 31 (described later) of the resistor layer 3 in the y direction. The first through portion 18 and the plurality of second through portions 19 penetrate the substrate 1 from the base surface 11 (main surface 10) to the back surface 13. 2 and 5, when viewed along the z direction, the first through-holes 18 form slits extending in the x direction. As shown in Fig. 4, when viewed along the z direction, the second through-holes 19 are arranged in a staggered configuration with respect to the x direction.

[0035] As shown in FIG. 7, the substrate 1 has a first inner peripheral surface 181 and a plurality of second inner peripheral surfaces 191. The first inner peripheral surface 181 and each of the plurality of second inner peripheral surfaces 191 are connected to the base surface 11 (main surface 10) and the back surface 13. The first inner peripheral surface 181 defines a first penetration portion 18. The first inner peripheral surface 181 is made up of a plurality of regions inclined with respect to each of the base surface 11 and the back surface 13. Of the plurality of regions, a pair of the regions positioned apart from each other in the y direction are inclined with respect to the base surface 11 and the back surface 13 so as to approach each other from the base surface 11 to the back surface 13. Each of the plurality of second inner peripheral surfaces 191 defines one of the plurality of second penetration portions 19. Each of the plurality of second inner peripheral surfaces 191 stands up along the z direction.

[0036] 7, the first insulating layer 21 covers the main surface 10, the first inner peripheral surface 181, and the multiple second inner peripheral surfaces 191 of the substrate 1. The first insulating layer 21 electrically insulates the substrate 1 from the resistor layer 3, the wiring layer 4, the first through-wires 511, and the multiple second through-wires 512. The first insulating layer 21 is made of silicon dioxide (TEOS-SiO2) using tetraethyl orthosilicate (TEOS) as a raw material, for example. The thickness of the first insulating layer 21 is, for example, 1 μm or more and 15 μm or less.

[0037] As shown in FIG. 7, the second insulating layer 22 covers the rear surface 13 of the substrate 1. At the boundaries between the rear surface 13 and the first inner peripheral surface 181 and the multiple second inner peripheral surfaces 191 of the substrate 1, the second insulating layer 22 is connected to the first insulating layer 21. The second insulating layer 22 electrically insulates the substrate 1 from the first electrode 521, the multiple second electrodes 522, and the heat dissipation layer 53. The second insulating layer 22 is made of, for example, silicon dioxide or silicon nitride (Si3N4). As shown in FIG. 9 and FIG. 10, the second insulating layer 22 has a first opening 221 and multiple second openings 222 formed therein. In the z direction, the first opening 221 and the second opening 222 penetrate the second insulating layer 22. The first opening 221 communicates with the first through portion 18 of the substrate 1. The multiple second openings 222 communicate individually with the multiple second through portions 19 of the substrate 1.

[0038] The resistor layer 3 is formed on the main surface 10 of the substrate 1, as shown in Figs. 7 to 10. The resistor layer 3 is in contact with the first insulating layer 21. As a result, in the thermal printhead A10, the first insulating layer 21 is sandwiched between the substrate 1 and the resistor layer 3. Furthermore, a portion of the resistor layer 3 is accommodated in the first through portion 18 and the multiple second through portions 19 of the substrate 1. The resistor layer 3 is made of, for example, tantalum nitride (TaN). An example of the thickness of the resistor layer 3 is 0.02 µm or more and 0.1 µm or less.

[0039] As shown in FIGS. 2, 3 and 8, the resistor layer 3 includes a plurality of heat generating portions 31. In the resistor layer 3, the plurality of heat generating portions 31 are portions exposed from the wiring layer 4. When the plurality of heat generating portions 31 are selectively energized from the wiring layer 4, the plurality of heat generating portions 31 locally heat the recording medium 78 shown in FIG. 6. The plurality of heat generating portions 31 are arranged in the x direction. Of the plurality of heat generating portions 31, two adjacent heat generating portions 31 in the x direction are positioned apart from each other. In the convex surface 12 of the substrate 1, the plurality of heat generating portions 31 are formed on the top surface 121. As shown in FIG. 6, in the thermal printer, a platen roller 79 faces the plurality of heat generating portions 31.

[0040] The wiring layer 4 is formed on the resistor layer 3 as shown in Figs. 7 to 10. The wiring layer 4 forms a conductive path for passing electricity to the multiple heat generating parts 31 of the resistor layer 3. The electrical resistivity of the wiring layer 4 is smaller than that of the resistor layer 3. The wiring layer 4 is a metal layer made of, for example, copper (Cu). An example of the thickness of the wiring layer 4 is 0.3 µm or more and 2.0 µm or less. Alternatively, the wiring layer 4 may be configured to be made of two metal layers, a titanium (Ti) layer laminated on the resistor layer 3 and a copper layer laminated on the titanium layer. In this case, an example of the thickness of the titanium layer is 0.1 µm or more and 0.2 µm or less.

[0041] As shown in Fig. 2, the wiring layer 4 includes a common wiring 41 and a plurality of individual wirings 42. The common wiring 41 is located on one side in the y direction (downstream side) of the plurality of heat generating portions 31 of the resistor layer 3. The plurality of individual wirings 42 are located on the other side in the y direction (upstream side) of the plurality of heat generating portions 31. As shown in Fig. 3, when viewed along the z direction, a plurality of regions of the resistor layer 3 sandwiched between the common wiring 41 and the plurality of individual wirings 42 are the plurality of heat generating portions 31. As will be described later, a predetermined positive voltage is supplied to the common wiring 41 from a power supply terminal (not shown) of the connector 77.

[0042] As shown in FIG. 2 and FIG. 3, the common wiring 41 has a base 411 and a plurality of extensions 412. In the y direction, the base 411 is located farthest from the plurality of heat generating parts 31 of the resistor layer 3. The base 411 is a strip extending in the x direction when viewed along the z direction. When viewed along the z direction, the base 411 overlaps with the first through portion 18 of the substrate 1. The plurality of extensions 412 are strip-shaped extending from an end of the base 411 facing the protrusion 17 of the substrate 1 in the y direction toward the plurality of heat generating parts 31. The plurality of extensions 412 are arranged along the x direction. A portion of each of the plurality of extensions 412 is formed on the inclined surface 122 facing the base 411, of the pair of inclined surfaces 122 of the substrate 1. Therefore, a portion of the common wiring 41 is formed on the inclined surface 122 on the downstream side of the pair of inclined surfaces 122. In the common wiring 41 , a current flows from the base portion 411 through the plurality of extending portions 412 to the plurality of heat generating portions 31 .

[0043] As shown in FIG. 2 and FIG. 4, each of the individual wirings 42 has a base 421 and an extension 422. In the y direction, the base 421 is located farthest from the heat generating parts 31 of the resistor layer 3. The bases 421 of the individual wirings 42 are arranged in a staggered arrangement in the x direction. When viewed along the z direction, the bases 421 of the individual wirings 42 individually overlap the second through parts 19 of the substrate 1. The extension 422 is a strip extending from an end of the base 421 facing the protrusion 17 of the substrate 1 in the y direction toward the heat generating parts 31. The extension 422 of the individual wirings 42 is arranged along the x direction. The extension 422 of each of the individual wirings 42 is formed on one of a pair of inclined surfaces 122 of the substrate 1 that faces the base 421 of the individual wirings 42. Therefore, a portion of each of the multiple individual wirings 42 is formed on the upstream inclined surface 122 of the pair of inclined surfaces 122. In each of the multiple individual wirings 42, a current flows from the base 421 through the extending portion 422 to one of the multiple heat generating portions 31. When viewed along the z direction, each of the multiple heat generating portions 31 is sandwiched between one of the extending portions 422 of the multiple individual wirings 42 and one of the extending portions 412 of the common wiring 41.

[0044] As shown in FIG. 7 and FIG. 9, the first through wiring 511 is accommodated in the first through portion 18 of the substrate 1. The first through wiring 511 has a base layer 511A and a main layer 511B. The base layer 511A is formed along the first inner circumferential surface 181 of the substrate 1 and is in contact with the resistor layer 3. The base layer 511A is connected to the base portion 411 of the common wiring 41. Therefore, the first through wiring 511 is connected to the common wiring 41. Furthermore, the base layer 511A is connected to the first opening 221 of the second insulating layer 22. The base layer 511A is made of the same metal layer as the metal layer constituting the wiring layer 4. The main layer 511B is surrounded by the base layer 511A and fills the first through portion 18. The volume of the main layer 511B is larger than the volume of the base layer 511A. The main layer 511B is made of, for example, copper.

[0045] As shown in FIG. 7 and FIG. 10, the second through wirings 512 are individually accommodated in the second through portions 19 of the substrate 1. Each of the second through wirings 512 is formed along any one of the second inner circumferential surfaces 191 of the substrate 1 and is in contact with the resistor layer 3. The second through wirings 512 are individually connected to the bases 421 of the individual wirings 42. Therefore, each of the second through wirings 512 is connected to any one of the individual wirings 42. Furthermore, the second through wirings 512 are individually connected to the second openings 222 of the second insulating layer 22. Each of the second through wirings 512 is made of the same metal layer as the metal layer constituting the wiring layer 4.

[0046] The first electrode 521 is formed on the rear surface 13 of the substrate 1 as shown in FIG. 5 and FIG. 7. The first electrode 521 is in contact with the second insulating layer 22. The first electrode 521 is in the shape of a strip extending in the x direction as viewed along the z direction. As viewed along the z direction, the first electrode 521 overlaps at least a part of the first through portion 18 of the substrate 1. As shown in FIG. 9, the first electrode 521 has a base layer 521A and a main body layer 521B. The base layer 521A is in contact with the second insulating layer 22. Furthermore, the base layer 521A is in contact with the resistor layer 3 and the base layer 511A of the first through wiring 511 at the first opening 221 of the second insulating layer 22. As a result, the first electrode 521 is connected to the first through wiring 511 and is electrically connected to the common wiring 41 via the first through wiring 511. A predetermined positive voltage is applied to the first electrode 521. The base layer 521A is composed of two metal layers: a barrier layer in contact with the second insulating layer 22, the resistor layer 3, and the first through-hole wiring 511, and a seed layer laminated on the barrier layer. The barrier layer is made of, for example, titanium. The seed layer is made of, for example, copper. The main body layer 521B is laminated on the base layer 521A. In the first electrode 521, the main body layer 521B becomes a main conductive path. The main body layer 521B is a metal layer made of, for example, copper.

[0047] The second electrodes 522 are formed on the rear surface 13 of the substrate 1 as shown in FIG. 5 and FIG. 7. The second electrodes 522 are in contact with the second insulating layer 22. Each of the second electrodes 522 is rectangular when viewed along the z direction. When viewed along the z direction, the second electrodes 522 are individually overlapped with the second through-holes 19 of the substrate 1. As shown in FIG. 10, each of the second electrodes 522 has a base layer 522A and a main layer 522B. The base layer 522A is in contact with the second insulating layer 22. Furthermore, the base layer 522A is in contact with the resistor layer 3 and any of the second through-wires 512 in any of the second openings 222 of the second insulating layer 22. As a result, each of the second electrodes 522 is connected to any of the second through-wires 512 and is electrically connected to any of the individual wirings 42 via the second through-wires 512. The base layer 522A is made of a metal layer. The metal layer is the same as the metal layer constituting the base layer 521A of the first electrode 521. The main layer 522B is laminated on the base layer 522A. In each of the multiple second electrodes 522, the main layer 522B serves as a main conductive path. The main layer 522B is made of a metal layer. The metal layer is the same as the metal layer constituting the main layer 521B of the first electrode 521.

[0048] As shown in FIG. 5 and FIG. 7, the heat dissipation layer 53 is formed on the rear surface 13 of the substrate 1 and in contact with the second insulating layer 22. In the y direction, the heat dissipation layer 53 is located between the first electrode 521 and the plurality of second electrodes 522. The heat dissipation layer 53 is in the form of a strip extending in the x direction when viewed along the z direction. When viewed along the z direction, the heat dissipation layer 53 overlaps the plurality of heat generating portions 31 of the resistor layer 3. As shown in FIG. 8, the heat dissipation layer 53 has a base layer 53A and a main layer 53B. The base layer 53A is in contact with the second insulating layer 22. The base layer 53A is made of a metal layer. The metal layer is the same as the metal layer constituting the base layer 521A of the first electrode 521. The main layer 53B is laminated on the base layer 53A. The main layer 53B is made of a metal layer. This metal layer is the same as the metal layer constituting main body layer 521B of first electrode 521.

[0049] As shown in FIG. 7, the protective layer 6 covers the main surface 10 of the substrate 1, a portion of each of the first through wires 511, the heat generating portions 31 of the resistor layer 3, and the wiring layer 4. The protective layer 6 has electrical insulation properties. The protective layer 6 is made of, for example, any one of silicon dioxide, silicon nitride, silicon carbide (SiC), and aluminum nitride (AlN). Alternatively, the protective layer 6 may be a laminate made of a plurality of types of these materials. An example of the thickness of the protective layer 6 is 1.0 μm or more and 10 μm or less. In the thermal printer, a recording medium 78 shown in FIG. 6 is pressed against the area of ​​the protective layer 6 covering the heat generating portions 31 by a platen roller 79.

[0050] As shown in Fig. 6, wiring board 71 is disposed opposite rear surface 13 of substrate 1. As shown in Fig. 1, the area of ​​wiring board 71 is larger than the area of ​​substrate 1 when viewed along the z direction. When viewed along the z direction, wiring board 71 has a rectangular shape with the x direction as the longitudinal direction. Wiring board 71 is, for example, a PCB substrate. Substrate 1, a plurality of driving elements 73, and a connector 77 are mounted on wiring board 71.

[0051] As shown in FIGS. 11 and 12, the wiring board 71 has a heat sink 711 and wiring 712. The heat sink 711 penetrates the wiring board 71 in the z-direction. The heat sink 711 is a metal layer made of, for example, copper. The heat sink 711 is joined to the heat dissipation layer 53. The wiring 712 is disposed on the upper surface of the wiring board 71. The wiring 712 forms a conductive path between the first electrode 521, the multiple second electrodes 522, the multiple driving elements 73, and the connector 77 in the wiring board 71. The first electrode 521 and the multiple second electrodes 522 are joined to the wiring 712.

[0052] 6, the heat sink 72 is located on the opposite side of the wiring board 71 from the substrate 1 in the z direction. The wiring board 71 is joined to the heat sink 72. When the thermal printhead A10 is in use, a portion of the heat generated from the multiple heat generating portions 31 of the resistor layer 3 is conducted to the heat sink 72 via the substrate 1 and the heat dissipation layer 53. The heat conducted to the heat sink 72 is dissipated to the outside. The heat sink 72 is made of, for example, aluminum (Al).

[0053] As shown in Figs. 1 and 6, the driving elements 73 are mounted on the wiring board 71 via an electrically insulating die bonding material (not shown). Each of the driving elements (driver ICs) 73 is a semiconductor element in which various circuits are configured. One end of each of the first wires 74 and one end of each of the second wires 75 are joined to each of the driving elements 73. The other end of each of the first wires 74 is joined to wiring 712 of the wiring board 71 to which the second electrodes 522 are joined. The other end of each of the second wires 75 is joined to wiring 712 that is electrically connected to the connector 77.

[0054] With the above-mentioned configuration, a print signal, a control signal, and a predetermined positive voltage are input from the outside to the multiple drive elements 73 via the connector 77. The multiple drive elements 73 each perform a switching operation based on these electrical signals, thereby selectively applying a predetermined positive voltage or 0V to the multiple individual wirings 42. Since a predetermined positive voltage is applied to the common wiring 41, when 0V is applied to any one of the multiple individual wirings 42, a current flows from the common wiring 41 to any one of the multiple heat generating portions 31 of the resistor layer 3 that is conductive to that individual wiring 42. As a result, the multiple heat generating portions 31 selectively generate heat.

[0055] 6, the sealing resin 76 covers the driving elements 73, the first wires 74, the second wires 75, and a part of the wiring board 71. The sealing resin 76 has electrical insulation properties. The sealing resin 76 is a black, soft synthetic resin that is used as an underfill, for example.

[0056] As shown in Figs. 1 and 6, the connector 77 is mounted on one end (upstream side) of the wiring board 71 in the y direction. The connector 77 is connected to a thermal printer. The connector 77 has a plurality of pins (not shown). Some of the plurality of pins are electrically connected to the wiring 712 to which the first electrode 521 is joined. The remaining pins of the plurality of pins are electrically connected to the wiring 712 of the wiring board 71 to which the plurality of second wires 75 are joined.

[0057] Next, an example of a manufacturing method for the thermal printhead A10 will be described with reference to Figures 13 to 34. Here, the cross-sectional positions of Figures 13 to 33 (excluding Figures 28 to 32) are the same as the cross-sectional position of Figure 7 showing the main part of the thermal printhead A10.

[0058] First, as shown in FIGS. 13 and 14, the protrusions 17 are formed on the base material 81.

[0059] First, as shown in FIG. 13, a first mask layer 891 is formed to cover the base material 81. The base material 81 is made of a semiconductor material. The semiconductor material includes a single crystal material of silicon. The base material 81 is a silicon wafer. A plurality of substrates 1 are connected in a direction perpendicular to the z direction to form the base material 81. The base material 81 has a first surface 81A and a second surface 81B. The first surface 81A and the second surface 81B face opposite each other in the z direction. The first surface 81A and the second surface 81B of the base material 81 are both surfaces with Miller indices (100). The first mask layer 891 is formed to cover the first surface 81A and the second surface 81B. The first mask layer 891 is made of silicon nitride. In forming the first mask layer 891, first, a thin film of silicon nitride is formed to cover the first surface 81A and the second surface 81B by thermal CVD (Chemical Vapor Deposition). Next, a portion of the region of the thin film of silicon nitride covering the first surface 81A is removed by lithography patterning and reactive ion etching (RIE), thereby forming a first mask layer 891 that covers a portion of the first surface 81A and the second surface 81B.

[0060] Next, as shown in FIG. 14, the main surface 10 and the convex portion 17 are formed on the base material 81. The main surface 10 and the convex portion 17 are formed by wet etching the area of ​​the first surface 81A exposed from the first mask layer 891 shown in FIG. 13 using an aqueous solution of potassium hydroxide (KOH). The etching is anisotropic. Next, the area of ​​the first mask layer 891 covering the first surface 81A is removed by wet etching using hydrofluoric acid (HF). As a result, the main surface 10 including the base surface 11 and the convex surface 12 and the convex portion 17 are formed on the base material 81. The convex surface 12 bulges in the z direction from the base surface 11. The convex portion 17 bulges in the z direction from the base surface 11 and extends along the x direction. The convex portion 17 includes the convex surface 12. The area of ​​the first surface 81A covered by the first mask layer 891 becomes the top surface 121 of the convex surface 12. Furthermore, the inclination angles α (see FIG. 8) of the pair of inclined surfaces 122 of the convex surface 12 with respect to the base surface 11 are both the same. This is because the convex portion 17 is formed by anisotropic etching.

[0061] Next, as shown in FIGS. 15 and 16, a first recess 811 recessed in the z direction from the base surface 11 (principal surface 10) is formed in the substrate 81.

[0062] First, as shown in FIG. 15, a second mask layer 892 is formed to cover the main surface 10 of the substrate 81. The second mask layer 892 is made of silicon nitride. To form the second mask layer 892, first, a thin film of silicon nitride is formed to cover the main surface 10 by thermal CVD. Next, a portion of the thin film of silicon nitride covering the base surface 11 is removed by lithography patterning and reactive ion etching. This forms the second mask layer 892 that covers a portion of the main surface 10.

[0063] Next, as shown in FIG. 16, a first recess 811 is formed in the substrate 81. The first recess 811 is formed by wet etching using an aqueous potassium hydroxide solution on the region of the base surface 11 exposed from the second mask layer 892 shown in FIG. 15. The etching is anisotropic. Finally, the second mask layer 892 is removed by wet etching using hydrofluoric acid. In this manner, the first recess 811 is formed in the substrate 81. Furthermore, a first inner circumferential surface 181 that defines the first recess 811 is formed in the substrate 81.

[0064] 17 and 18, a plurality of second recesses 812 recessed in the z direction from the base surface 11 (principal surface 10) are formed in the substrate 81. The second recesses 812 are located on the opposite side of the first recesses 811 in the y direction with respect to the heat generating portions 31 of the resistor layer 3 shown in FIG.

[0065] First, as shown in FIG. 17, a third mask layer 893 is formed to cover the main surface 10 and the first inner peripheral surface 181 of the substrate 81. The third mask layer 893 is made of silicon nitride. To form the third mask layer 893, first, a thin film of silicon nitride is formed by thermal CVD to cover the main surface 10 and the first inner peripheral surface 181. Next, a portion of the thin film of silicon nitride covering the base surface 11 is removed by lithography patterning and reactive ion etching. This forms the third mask layer 893 that covers a portion of the main surface 10 and the first inner peripheral surface 181.

[0066] Next, as shown in Fig. 18, a plurality of second recesses 812 are formed in the substrate 81. The plurality of second recesses 812 are formed by deep RIE in each of a plurality of regions of the base surface 11 exposed from the third mask layer 893 shown in Fig. 17. Finally, the third mask layer 893 is removed by wet etching using hydrofluoric acid. In this manner, a plurality of second recesses 812 are formed in the substrate 81. Furthermore, a plurality of second inner circumferential surfaces 191 that individually define the plurality of second recesses 812 are formed in the substrate 81.

[0067] 19, a first insulating layer 21 is formed to cover the main surface 10, the first inner circumferential surface 181, and the multiple second inner circumferential surfaces 191 of the base material 81. The first insulating layer 21 is formed by laminating thin films of TEOS-SiO2 multiple times by plasma CVD.

[0068] Next, as shown in FIG. 20 to FIG. 24, the resistor layer 3 and the wiring layer 4 are formed. The resistor layer 3 includes a plurality of heat generating parts 31 arranged in the x direction. The wiring layer 4 is electrically connected to the plurality of heat generating parts 31. Furthermore, the step of forming the wiring layer 4 includes a step of forming a common wiring 41, a plurality of individual wirings 42, a first through wiring 511, and a plurality of second through wirings 512. In the base material 81, the common wiring 41 is located on one side (downstream side) in the y direction with respect to the plurality of heat generating parts 31 of the resistor layer 3 shown in FIG. 24. In the base material 81, the plurality of individual wirings 42 are located on the other side (upstream side) in the y direction with respect to the plurality of heat generating parts 31 shown in FIG. 24. The first through wiring 511 is accommodated in the first recess 811 of the base material 81 and is connected to the common wiring 41. The second through wiring 512 is individually accommodated in the plurality of second recesses 812 of the base material 81 and is individually connected to the plurality of individual wirings 42.

[0069] 20, a resistor film 82 is formed on the main surface 10 of the substrate 81, in the first recess 811, and in the multiple second recesses 812 of the substrate 81. The resistor film 82 is formed so as to cover the entire surface of the first insulating layer 21. The resistor film 82 is formed by laminating a thin film of tantalum nitride on the first insulating layer 21 by a sputtering method.

[0070] 21, a conductive layer 83 is formed to cover the entire surface of the resistor film 82. The conductive layer 83 is formed by laminating a plurality of copper thin films on the resistor film 82 by a sputtering method. Alternatively, the conductive layer 83 may be formed by laminating a titanium thin film on the resistor film 82 by a sputtering method, and then laminating a plurality of copper thin films on the titanium thin film by a sputtering method. As a result, the base layer 511A of the first through wiring 511 is formed in the first recess 811 of the substrate 81. Furthermore, a plurality of second through wirings 512 are formed individually in the plurality of second recesses 812 of the substrate 81.

[0071] 22, a main body layer 511B of the first through wiring 511 is formed in the first recess 811 of the base material 81. The main body layer 511B is made of copper. The main body layer 511B is formed by subjecting the conductive layer 83 to lithographic patterning, and then by electrolytic plating using the conductive layer 83 as a conductive path. As a result, the first through wiring 511 is formed in the first recess 811.

[0072] 23, lithography patterning is performed on the conductive layer 83, and then a portion of the conductive layer 83 is removed. The removal is performed by wet etching using a mixed solution of sulfuric acid (H2SO4) and hydrogen peroxide (H2O2). As a result, the common wiring 41 and a plurality of individual wirings 42 are formed on the resistor film 82. Thus, the formation of the wiring layer 4 is completed by this process. Furthermore, the region of the resistor film 82 formed on the top surface 121 (convex surface 12) of the base material 81 is exposed from the wiring layer 4.

[0073] 24, the resistor film 82, the wiring layer 4, and the main layer 511B of the first through wire 511 are lithographically patterned, and then a portion of the resistor film 82 is removed. The removal is performed by reactive ion etching. As a result, the resistor layer 3 is formed on the main surface 10 of the substrate 81, in the first recess 811 of the substrate 81, and in the multiple second recesses 812. A multiple heat generating portion 31 is formed on the top surface 121 of the substrate 81.

[0074] 25, a protective layer 6 is formed to cover the main surface 10 of the base material 81, parts of the first through wirings 511, the heat generating portions 31 of the resistor layer 3, and the wiring layer 4. The protective layer 6 is formed by laminating thin films of silicon nitride by plasma CVD.

[0075] Next, as shown in FIG. 26, a part of the base material 81 located on the opposite side to the main surface 10 in the z direction is removed. The removal is performed by polishing. Furthermore, the removal is performed until a part of the first through wiring 511 and a part of each of the plurality of second through wirings 512 are exposed from the base material 81. As a result, a part of the base material 81 including the second surface 81B and a region of the first mask layer 891 covering the second surface 81B are removed. Furthermore, the base material 81 has a back surface 13 facing the opposite side to the main surface 10 in the z direction. A part of the first through wiring 511 and a part of each of the plurality of second through wirings 512 are exposed from the back surface 13. Furthermore, a part of each of the first insulating layer 21 and the resistor layer 3 is exposed from the back surface 13. Through this process, the first recess 811 of the base material 81 becomes the first through portion 18. In addition, the plurality of second recesses 812 of the base material 81 become the plurality of second through portions 19.

[0076] Next, as shown in FIG. 27, a second insulating layer 22 is formed to cover the rear surface 13 of the substrate 81. The second insulating layer 22 is made of silicon nitride. The second insulating layer 22 is formed with a first opening 221 penetrating in the z direction and a plurality of second openings 222. In forming the second insulating layer 22, first, a thin film of silicon nitride covering the rear surface 13 is formed by plasma CVD. Then, a part of the thin film of silicon nitride covering the rear surface 13 is removed by lithography patterning and reactive ion etching. As a result, the second insulating layer 22 covering the rear surface 13 is formed, and the first opening 221 and a plurality of second openings 222 are formed in the second insulating layer 22. As shown in FIG. 28 and FIG. 29, the second insulating layer 22 is connected to the first insulating layer 21 at the boundaries between the rear surface 13 and the first inner peripheral surface 181 and the plurality of second inner peripheral surfaces 191 of the substrate 81. 28, a portion of the resistor layer 3 and a portion of the base layer 511A of the first through wiring 511 are exposed from the first opening 221. As shown in FIG. 29, a portion of the resistor layer 3 and a portion of each of the multiple second through wirings 512 are exposed from any of the multiple second openings 222.

[0077] Next, as shown in FIGS. 28 to 33, electrodes (a first electrode 521 and a plurality of second electrodes 522) and a heat dissipation layer 53 are formed. The first electrode 521 is electrically connected to the common wiring 41. The plurality of second electrodes 522 are individually electrically connected to the plurality of individual wirings 42. The first electrode 521, the plurality of second electrodes 522, and the heat dissipation layer 53 are disposed on the rear surface 13 of the base material 81 and in contact with the second insulating layer 22. That is, the first electrode 521, the plurality of second electrodes 522, and the heat dissipation layer 53 are positioned on the opposite side of the base material 81 to the wiring layer 4 in the z direction.

[0078] First, as shown in FIG. 28 and FIG. 29, a base layer 84 is formed to cover the second insulating layer 22. The base layer 84 is formed by laminating a thin film of titanium on the second insulating layer 22 by a sputtering method, and then laminating a thin film of copper on the thin film of titanium by a sputtering method. As a result, the base layer 84 is formed in the first opening 221 of the second insulating layer 22 and also in the multiple second openings 222 of the second insulating layer 22. The base layer 84 formed in the first opening 221 contacts the resistor layer 3 and the base layer 511A of the first through wire 511. The base layer 84 formed in the multiple second openings 222 contacts the resistor layer 3 and the multiple second through wires 512.

[0079] 30 to 32, a plurality of main body layers 85 are formed on the base layer 84. The plurality of main body layers 85 are made of copper. The plurality of main body layers 85 are formed by subjecting the base layer 84 to lithography patterning, and then by electrolytic plating using the base layer 84 as a conductive path.

[0080] 33, the regions of the base layer 84 that are not covered by the plurality of main body layers 85 are removed by wet etching using a mixed solution of sulfuric acid and hydrogen peroxide. As a result, the first electrode 521, the plurality of second electrodes 522, and the heat dissipation layer 53 are formed.

[0081] Next, the base material 81 is cut along the x-direction and the y-direction to divide the base material 81 into individual pieces. This results in the main part of the thermal printhead A10 including the substrate 1. Next, the wiring board 71 is provided with a plurality of driving elements 73 and a connector 77, a plurality of first wires 74 and a plurality of second wires 75 are joined, and a sealing resin 76 is formed. Next, the heat dissipation layer 53 is joined to the heat sink 711 of the wiring board 71, and the first electrode 521 and a plurality of second electrodes 522 are joined to the wiring 712 of the wiring board 71. Finally, the wiring board 71 is joined to the heat sink 72. Through the above steps, the thermal printhead A10 is obtained.

[0082] Next, the function and effect of the thermal printhead A10 will be described.

[0083] The thermal printhead A10 has a main surface 10 and a back surface 13, and includes a substrate (semiconductor substrate) 1 made of a semiconductor material, a wiring layer 4 formed on a resistor layer 3, and a first electrode 521 formed on the back surface 13. The wiring layer 4 includes a common wiring 41 located on one side (downstream side) in the y direction with respect to the plurality of heat generating parts 31 of the resistor layer 3. Meanwhile, the substrate 1 is formed with a first through portion 18 penetrating from the main surface 10 to the back surface 13. The first through portion 18 houses a first through wiring 511. The first through wiring 511 is connected to the common wiring 41 and the first electrode 521. With this configuration, it is possible to ensure a conduction path of the common wiring 41 in the thermal printhead A10 without widely arranging the common wiring 41 on the main surface 10 on the other side (upstream side) in the y direction with respect to the plurality of heat generating parts 31. This makes it possible to increase the number of individual wirings 42 located on the other side in the y direction of the heat generating parts 31 without increasing the area of ​​the main surface 10, thereby making it possible to increase the number of heat generating parts 31 while reducing the width (length in the x direction) of each of the heat generating parts 31. Therefore, the thermal printhead A10 makes it possible to perform finer printing without increasing the size of the substrate 1.

[0084] In the thermal printhead A10, since it is required to more quickly pass the current flowing from the multiple heat generating parts 31 to the common wiring 41, the thickness of the common wiring 41 is made larger than the thickness of each of the multiple individual wirings 42. Therefore, by providing the thermal printhead A10 with the first through wiring 511 and the first electrode 521, the area of ​​the common wiring 41 when viewed along the z direction can be further reduced. This makes it possible to suppress warping of the substrate 1 in the z direction caused by the difference between the linear expansion coefficient of the substrate 1 and the linear expansion coefficient of the wiring layer 4.

[0085] The thermal printhead A10 further includes a plurality of second electrodes 522 formed on the rear surface 13 of the substrate 1. Meanwhile, the substrate 1 is formed with a plurality of second through-holes 19 that penetrate from the main surface 10 to the rear surface 13 and are located on the opposite side of the first through-holes 18 with respect to the plurality of heat generating parts 31 in the y direction. The plurality of second through-holes 19 individually accommodate a plurality of second through-wires 512. Each of the plurality of second through-wires 512 is connected to one of the plurality of individual wirings 42 and one of the plurality of second electrodes 522. This results in a configuration in which the plurality of second electrodes 522 and the first electrode 521 are formed at the same position in the z direction in the substrate 1. This makes it possible to avoid a complication of the structure of the wiring substrate 71 to which the plurality of second electrodes 522 and the first electrode 521 are joined.

[0086] The main surface 10 of the substrate 1 includes a base surface 11 and a convex surface 12 that bulges out from the base surface 11 in the z direction. The convex surface 12 extends along the x direction. The multiple heat generating portions 31 are formed on the convex surface 12. This makes it possible to reduce the contact area of ​​the thermal printhead A10 with the recording medium 78 (see FIG. 6) when the thermal printhead A10 is in use. This makes it possible to improve the quality of printing on the recording medium 78 caused by the multiple heat generating portions 31.

[0087] Furthermore, the convex surface 12 includes a top surface 121 parallel to the base surface 11 of the substrate 1, and a pair of inclined surfaces 122 that are connected to the top surface 121 and the base surface 11 and are spaced apart from each other in the y direction. The plurality of heat generating portions 31 are formed on the top surface 121. A part of the common wiring 41 and a part of each of the plurality of individual wirings 42 are formed on one of the pair of inclined surfaces 122. This makes it possible to reduce the dimension of each of the plurality of heat generating portions 31 in the y direction as viewed along the z direction, while further reducing the contact area of ​​the recording medium 78 with the thermal printhead A10 when the thermal printhead A10 is in use. Therefore, it is possible to further improve the quality of printing on the recording medium 78 while suppressing the amount of heat generated in the thermal printhead A10.

[0088] In the substrate 1, the pair of inclined surfaces 122 are inclined with respect to the base surface 11 so as to approach each other from the base surface 11 to the top surface 121. Such a shape of the convex surface 12 is obtained by forming the convex portion 17 on the base material 81 by anisotropic etching in the manufacturing method of the thermal printhead A10. This is because the semiconductor material constituting the base material 81 contains a single crystal silicon material.

[0089] The thermal printhead A10 further includes a first insulating layer 21 and a second insulating layer 22. The first insulating layer 21 covers the main surface 10 of the substrate 1, as well as a first inner peripheral surface 181 that defines the first through-hole 18 and a plurality of second inner peripheral surfaces 191 that define each of the plurality of second through-holes 19. The second insulating layer 22 covers the rear surface 13 of the substrate 1 and is connected to the first insulating layer 21. This allows the thermal printhead A10 to be electrically insulated from the substrate 1 even if the thermal printhead A10 includes the first through-hole wiring 511, the plurality of second through-hole wirings 512, the first electrode 521, and the plurality of second electrodes 522. Therefore, in the wiring layer 4, a short circuit between the common wiring 41 and the plurality of individual wirings 42 is prevented.

[0090] The thermal printhead A10 further includes a heat dissipation layer 53 located between the first electrode 521 and the multiple second electrodes 522 in the y direction and formed in contact with the second insulating layer 22. When viewed along the z direction, the heat dissipation layer 53 overlaps the multiple heat generating parts 31. This allows a portion of the heat generated from the multiple heat generating parts 31 to be rapidly conducted from the substrate 1 to the heat dissipation layer 53 when the thermal printhead A10 is in use.

[0091] The thermal printhead A10 further includes a wiring board 71 to which a first electrode 521 and a plurality of second electrodes 522 are bonded. The wiring board 71 has a heat sink 711 to which the heat dissipation layer 53 is bonded. Thereby, in the above-mentioned case, the heat conducted to the heat dissipation layer 53 is quickly released to the outside via the heat sink 711.

[0092] A thermal printhead A20 according to a second embodiment of the first aspect of the present disclosure will be described with reference to Figures 34 and 35. In these figures, elements that are the same as or similar to those of the thermal printhead A10 described above are given the same reference numerals, and duplicated explanations will be omitted. Here, the cross-sectional position in Figure 34 is the same as the cross-sectional position in Figure 6 showing the thermal printhead A10 described above.

[0093] In the thermal printhead A20, the configuration of the convex surface 12 of the substrate 1 differs from that of the thermal printhead A10 described above.

[0094] 34 and 35, each of the pair of inclined surfaces 122 of the convex surface 12 includes a first region 122A and a second region 122B. The first region 122A is connected to the base surface 11 of the substrate 1. The second region 122B is connected to the top surface 121 of the convex surface 12 and the first region 122A. In each of the pair of inclined surfaces 122, the inclination angle α2 of the second region 122B with respect to the base surface 11 is smaller than the inclination angle α1 of the first region 122A with respect to the base surface 11.

[0095] Next, the function and effect of the thermal printhead A20 will be described.

[0096] The thermal printhead A20 has a main surface 10 and a back surface 13, and includes a substrate (semiconductor substrate) 1 made of a semiconductor material, a wiring layer 4 formed on a resistor layer 3, and a first electrode 521 formed on the back surface 13. The wiring layer 4 includes a common wiring 41 located on one side in the y direction with respect to a plurality of heat generating portions 31 of the resistor layer 3. Meanwhile, the substrate 1 is formed with a first through portion 18 penetrating from the main surface 10 to the back surface 13. The first through portion 18 contains a first through wiring 511. The first through wiring 511 is connected to the common wiring 41 and the first electrode 521. Therefore, the thermal printhead A20 also makes it possible to perform finer printing without increasing the size of the substrate 1.

[0097] In the thermal printhead A20, each of the pair of inclined surfaces 122 (convex surface 12) of the substrate 1 includes a first region 122A and a second region 122B. The first region 122A is connected to the base surface 11 of the substrate 1. The second region 122B is connected to the top surface 121 of the convex surface 12 and the first region 122A. In each of the pair of inclined surfaces 122, the inclination angle α2 of the second region 122B with respect to the base surface 11 is smaller than the inclination angle α1 of the first region 122A with respect to the base surface 11. By adopting this configuration, the surface of the protective layer 6 formed along the convex surface 12 becomes smoother. Therefore, when the recording medium 78 shown in FIG. 6 contacts the protective layer 6 during use of the thermal printhead A20, the kinetic frictional force of the recording medium 78 with respect to the protective layer 6 is reduced, so that, firstly, it is possible to suppress the adhesion of paper dust caused by the recording medium 78 to the protective layer 6. Secondly, the wear of the protective layer 6 is suppressed, thereby extending the life of the thermal printhead A20.

[0098] The present disclosure is not limited to the embodiment according to the first aspect described above. The specific configuration of each part of the present disclosure can be freely modified in various ways.

[0099] [Explanation of symbols according to the first aspect of the embodiment] A10, A20: Thermal print head 1: Substrate 10: Main surface 11: Base surface 12: Convex surface 121:Top surface 122:Slope surface 122A: 1st area 122B: 2nd area 13: Back side 17: protruding portion 18: first penetrating portion 181: first inner circumferential surface 19: Second penetration part 191: Second inner peripheral surface 21: First insulating layer 22: Second insulating layer 221: First opening 222: Second opening 3: Resistor layer 31: Heat generating part 4: Wiring layer 41: Common wiring 411: Base 412: Extension part 42: Individual wiring 421: Base 422: Extension 511: First through wiring 511A: Base layer 511B: Main layer 512: Second through-hole wiring 521: First electrode 521A: Base layer 521B: Main body layer 522: Second electrode 522A: Base layer 522B: Main body layer 53: Heat dissipation layer 53A: Base layer 53B: Main body layer 6: Protective layer 71: Wiring board 711: Heat sink 712: Wiring 72: Heat sink 73: Driving element 74: First wire 75: Second wire 76: Sealing resin 77: Connector 78: Recording medium 79: Platen roller 81: Base material 81A: 1st side 81B: 2nd side 811: First recess 812: Second recess 82: Resistor film 83: Conductive layer 84: Base layer 85: Main layer 891: First mask layer 892: Second mask layer 893: Third mask layer α, α1, α2: Inclination angle

[0100] Next, an embodiment according to the second aspect of the present disclosure will be described with reference to Figures 36 to 56. The reference symbols used in Figures 36 to 56 (second aspect) are unrelated to the reference symbols used in Figures 1 to 35 (first aspect), and the same reference symbols may refer to different components, or different reference symbols may refer to the same or similar components. The fact that the reference symbols used in the drawings relating to different aspects are unrelated to each other also applies to the drawings explaining the embodiments according to the third and fourth aspects described later.

[0101] In the conventional thermal printhead disclosed in Patent Document 1, there can be various types of print lengths in the main scanning direction. In order to manufacture thermal printheads with different print lengths in the main scanning direction, it is necessary to divide a Si wafer into a plurality of types of individual pieces with different lengths. There is a concern that the efficiency of manufacturing thermal printheads from a Si wafer decreases as the number of types of thermal printheads with different print lengths increases. Therefore, an object of a second aspect of the present disclosure is to provide a technology capable of increasing the manufacturing efficiency of thermal printheads with various different print lengths in the main scanning direction.

[0102] 36 to 39 show a thermal printhead according to an embodiment of the second aspect. A thermal printhead B10 of this embodiment includes a head substrate 1, a wiring substrate 5, a plurality of wires 61, 62, 63, a plurality of driving ICs 7, a resin part 78, a heat dissipation member 81, and a support member 82. The thermal printhead B10 is incorporated into a printer that prints on a print medium (not shown) transported by a platen roller 99 (see FIG. 39). Examples of print media include thermal paper for producing barcode sheets and receipts.

[0103] Fig. 36 is a plan view showing a thermal printhead B10. Fig. 37 is a cross-sectional view taken along line 037-037 in Fig. 36. Fig. 38 is a cross-sectional view of a main portion of the thermal printhead B10, and is an enlarged cross-sectional view of a portion of Fig. 39. Fig. 39 is an enlarged plan view of a main portion of the thermal printhead B10. For ease of understanding, the protective layer 2 is omitted in Figs. 36 and 39. For ease of understanding, the resin portion 78 is omitted in Figs. 36 and 39.

[0104] 37, in a thermal printhead B10, the head substrate 1 and the wiring substrate 5 are mounted adjacent to each other in the y direction on a heat dissipation member 81. In this embodiment, the head substrate 1 is supported by the heat dissipation member 81 via a support member 82. The head substrate 1 has a plurality of heat generating portions 41 arranged in the y direction (described later). The heat generating portions 41 are selectively driven to generate heat by a drive IC 7 mounted on the wiring substrate 5, and perform printing on a print medium pressed against the heat generating portions 41 by a platen roller 99 in accordance with a print signal transmitted from the outside via a connector 59.

[0105] The head substrate 1 includes a base material 10, an insulating layer 19, a protective layer 2, an electrode layer 3, and a resistor layer 4, as shown in FIGS.

[0106] The substrate 10 is made of a Si single crystal semiconductor. A suitable material for the substrate 10 is, for example, a Si wafer. As shown in FIG. 36, the substrate 10 has an elongated rectangular shape with the x direction as the longitudinal direction and the y direction as the transverse direction when viewed in the z direction. The substrate 10 is configured to include a plurality of individual chips 10A. The multiple individual chips 10A are lined up in the x direction.

[0107] The individual chip 10A has a first side surface 101 and a second side surface 102. The second side surface 102 is an end surface facing one side in the x direction (one side in the main scanning direction). The first side surface 101 is an end surface facing the other side in the x direction (the other side in the main scanning direction).

[0108] In this embodiment, a pair of individual chips 10A adjacent in the x direction are in close contact with each other. The first side surface 101 of the individual chip 10A located on one side in the x direction (one side in the main scanning direction) of the pair of individual chips 10A adjacent in the x direction is perpendicular to the x direction. The second side surface 102 of the individual chip 10A located on the other side in the x direction (the other side in the main scanning direction) of the pair of individual chips 10A adjacent in the x direction is perpendicular to the x direction. In the pair of individual chips 10A adjacent in the x direction, the first side surface 101 of the individual chip 10A located on one side in the x direction and the second side surface 102 of the individual chip 10A located on the other side in the x direction are in close contact with each other.

[0109] The size of the substrate 10 (the multiple individual chips 10A arranged in the x direction) is not limited, but as an example, the dimension in the x direction is, for example, about 50 mm to 400 mm, the dimension in the y direction is, for example, about 3 mm to 10 mm, and the dimension in the z direction is, for example, about 725 μm. As an example of the dimensions of the individual chips 10A, the dimension in the x direction is, for example, about 5 mm to 15 mm. In the substrate 10, the side closer to the driving IC 7 in the y direction is the upstream side, and the side farther from the driving IC 7 is the downstream side. The printing medium is transported from the upstream side to the downstream side in the y direction by a platen roller 99.

[0110] As shown in FIG. 37 to FIG. 39, the base material 10 (each individual chip 10A) has a main surface 11 and a protruding portion 12. The main surface 11 faces upward in the z direction. In the present disclosure, the main surface 11 spreads along the xy plane (a plane defined by the x direction and the y direction, the same applies to other planes) and is a plane substantially parallel to the xy plane. The main surface 11 is a plane with Miller indices (100). The protruding portion 12 protrudes from the main surface 11 in the z direction and extends in the x direction. The protruding portion 12 is formed near the downstream side of the main surface 11. The shape of the cross section of the protruding portion 12 along the yz plane is uniform in the x direction. The dimension of the protruding portion 12 in the y direction at the end on the lower side in the z direction is, for example, about 500 μm, and the dimension of the y direction at the end on the upper side in the z direction (a top surface 121 described later) is, for example, about 200 μm. The dimension of the protrusion 12 in the z direction is, for example, about 150 μm.

[0111] As shown in FIG. 38, the protrusion 12 has a top surface 121 and a pair of inclined surfaces 122. The top surface 121 is parallel to the main surface 11 and is a substantially flat surface. When viewed in the z direction, the top surface 121 is an elongated rectangular shape extending long in the x direction. The dimension of the protrusion 12 in the z direction is the separation distance between the top surface 121 and the main surface 11 in the z direction. The pair of inclined surfaces 122 sandwich the top surface 121 in the y direction. In addition, each of the pair of inclined surfaces 122 is connected to the main surface 11 and the top surface 121, and is sandwiched between them in the y direction. Each inclined surface 122 is inclined with respect to the main surface 11 and the top surface 121 so as to be lower as it moves away from the top surface 121 in the y direction. In other words, the pair of inclined surfaces 122 approach each other in the y direction as it moves away from the main surface 11 in the z direction. Each inclined surface 122 is a substantially flat surface. The inclination angle of each inclined surface 122 with respect to the main surface 11 is, for example, 54.8 degrees. Each inclined surface 122 is a (111) plane.

[0112] In this embodiment, the protrusions 12 are arranged on each of the multiple individual chips 10A. The positions of the protrusions 12 in the y direction are aligned on the multiple individual chips 10A. As a result, the protrusions 12 on each of the multiple individual chips 10A overlap when viewed in the x direction.

[0113] As shown in FIG. 38, the insulating layer 19 is formed on the main surface 11 of the substrate 10 and covers the substrate 10 (each chip 10A). The insulating layer 19 contacts the main surface 11, the top surface 121 of the protrusion 12, and a pair of inclined surfaces 122. The insulating layer 19 is for more reliably insulating the substrate 10 (each chip 10A) from the resistor layer 4 and the electrode layer 3. The insulating layer 19 may be formed in the region of the substrate 10 (each chip 10A) where the resistor layer 4 or the electrode layer 3 is formed. The insulating layer 19 is made of an insulating material, for example, SiO2 or SiN (silicon nitride), and preferably TEOS-SiO2 (SiO2 formed using TEOS (tetraethyl orthosilicate) as a raw material). The thickness of the insulating layer 19 is not particularly limited, and is, for example, 1 μm or more and 10 μm or less.

[0114] As shown in FIG. 38, the resistor layer 4 is formed on the insulating layer 19 and supported by the substrate 10 (plurality of individual chips 10A). The resistor layer 4 is formed across the main surface 11 and the protrusions 12 with the insulating layer 19 in between. The resistor layer 4 is made of, for example, TaN (tantalum nitride). The thickness of the resistor layer 4 is not particularly limited and is, for example, 0.02 μm or more and 0.1 μm or less (preferably about 0.08 μm). In this embodiment, the resistor layer 4 is arranged separately corresponding to each of the plurality of individual chips 10A.

[0115] The resistor layer 4 includes a plurality of heat generating portions 41, as shown in FIGS. 36, 38, and 39. The plurality of heat generating portions 41 are exposed portions of the resistor layer 4 that are not covered by the electrode layer 3 described below. The plurality of heat generating portions 41 are selectively energized to locally heat the print medium. The plurality of heat generating portions 41 are arranged in the x direction and are spaced apart from one another in the x direction. The formation area of ​​the plurality of heat generating portions 41 in the y direction is an area that includes part or all of the top surface 121 of the protrusion 12 in the y direction.

[0116] 36 and 39, a plurality of heat generating portions 41 are arranged on each of the plurality of individual chips 10A. In this embodiment, the plurality of heat generating portions 41 arranged on the substrate 10 are arranged at a constant pitch in the x direction across all of the plurality of individual chips 10A. The boundary between a pair of adjacent individual chips 10A in the x direction is located between a pair of heat generating portions 41 adjacent to each other in the x direction.

[0117] The electrode layer 3 constitutes a conductive path for passing electricity through the heat generating parts 41. The electrode layer 3 is laminated on the resistor layer 4 and supported by the substrate 10 (the plurality of individual chips 10A). The electrode layer 3 is made of a metal material having a smaller resistance value than the resistor layer 4, for example, Cu (copper). The thickness of the electrode layer 3 is not particularly limited, and is, for example, 0.3 μm or more and 2.0 μm or less. The electrode layer 3 may be configured by laminating a Cu layer and a Ti (titanium) layer. In this case, the Ti layer is interposed between the Cu layer and the resistor layer 4, and has a thickness of, for example, about 100 nm. In this embodiment, the electrode layer 3 is arranged separately corresponding to each of the plurality of individual chips 10A.

[0118] In this embodiment, the electrode layer 3 in each individual chip 10A includes a plurality of individual electrodes 31, a common electrode 32, and a plurality of relay electrodes 33, as shown in FIG.

[0119] The common electrode 32 has a plurality of common electrode extensions 321, a plurality of branch portions 322, and a main portion 323. The common electrode extensions 321 are strip-shaped extending along the y direction. The common electrode extensions 321 are disposed upstream of the heat generating portion 41 in the y direction. The common electrode extensions 321 are disposed at predetermined intervals in the x direction (main scanning direction).

[0120] A pair of branched parts 322 are connected to the downstream end of each common electrode extension 321 in the y direction. The branched parts 322 are strip-shaped extending in the y direction. The downstream end of each branched part 322 in the y direction extends to the inclined surface 122 on the upstream side in the y direction. The pair of branched parts 322 connected to the common electrode extension 321 are spaced apart from each other in the x direction and are in contact with a pair of heat generating parts 41 adjacent to each other in the x direction. As a result, each common electrode extension 321 is electrically connected to a pair of heat generating parts 41 adjacent to each other in the x direction via the pair of branched parts 322. The main part 323 is strip-shaped extending in the x direction and is disposed closer to the driving IC 7 in the y direction. The upstream end of each common electrode extension 321 in the y direction is connected to the main part 323.

[0121] The multiple individual electrodes 31 are separated from one another in the x direction. The individual electrodes 31 are arranged upstream of the heat generating portion 41 in the y direction. Each individual electrode 31 has an individual electrode extension portion 311 and an electrode pad portion 312. The individual electrode extension portion 311 is strip-shaped and extends generally along the y direction. The end portion on the downstream side in the y direction of the individual electrode extension portion 311 extends onto the inclined surface 122 on the upstream side in the y direction and contacts the heat generating portion 41. The electrode pad portion 312 is connected to the end portion on the upstream side in the y direction of the individual electrode extension portion 311. The electrode pad portion 312 is a portion to which the wire 61 is bonded.

[0122] Each individual electrode extension portion 311 is spaced apart from the common electrode extension portion 321 in the x direction. The individual electrode extension portions 311 are adjacent to each common electrode extension portion 321 on both sides in the x direction. That is, each common electrode extension portion 321 is sandwiched between two individual electrode extension portions 311 adjacent to each other on both sides in the x direction.

[0123] The heat generating portion 41 in contact with the individual electrode extension portion 311 is adjacent to the heat generating portion 41 in electrical conduction with the common electrode extension portion 321. More specifically, the heat generating portion 41 in contact with one of the two individual electrode extension portions 311 that sandwich the common electrode extension portion 321 is adjacent to one of the pair of heat generating portions 41 in electrical conduction with the common electrode extension portion 321. The heat generating portion 41 in contact with the other of the two individual electrode extension portions 311 that sandwich the common electrode extension portion 321 is adjacent to the other of the pair of heat generating portions 41 in electrical conduction with the common electrode extension portion 321.

[0124] The multiple relay electrodes 33 are arranged along the x direction. The multiple relay electrodes 33 are disposed downstream of the multiple heat generating portions 41 in the y direction, and are positioned on the opposite side in the y direction to the common electrode 32 and the multiple individual electrodes 31, with the multiple heat generating portions 41 in between. Each relay electrode 33 is in contact with a pair of heat generating portions 41 adjacent to each other in the x direction. Each of the multiple relay electrodes 33 is electrically interposed between one of the multiple individual electrodes 31 and the common electrode 32. Each relay electrode 33 has a pair of relay electrode extension portions 331 and a connecting portion 332.

[0125] As shown in Figs. 38 and 39, each relay electrode extension 331 has a strip shape extending in the y direction. The multiple relay electrode extensions 331 are spaced apart from each other in the x direction. The upstream end of each relay electrode extension 331 in the y direction extends onto the inclined surface 122 downstream in the y direction. Each pair of relay electrode extensions 331 constituting each relay electrode 33 is in contact with a pair of heat generating parts 41 adjacent to each other in the x direction. One of the pair of relay electrode extensions 331 in each relay electrode 33 is disposed to face one of the multiple branch parts 322 in the y direction with the heat generating part 41 therebetween. The other of the pair of relay electrode extensions 331 in each relay electrode 33 is disposed to face one of the multiple individual electrode extensions 311 in the y direction with the heat generating part 41 therebetween.

[0126] Each of the connecting portions 332 extends in the x direction. Each of the connecting portions 332 is connected to a pair of relay electrode extensions 331 in each of the relay electrodes 33. This allows the pair of relay electrode extensions 331 in each of the relay electrodes 33 to be electrically connected to each other.

[0127] A specific configuration example of the electrode layer 3 (multiple individual electrodes 31 and common electrode 32) has been described with reference to Figure 39, but the shapes of each individual electrode 31 and common electrode 32 when viewed in the z direction, i.e., the formation areas of each individual electrode 31 and common electrode 32, are not limited to the example of Figure 39.

[0128] As shown in Fig. 38, the protective layer 2 covers the electrode layer 3 and the resistor layer 4. The protective layer 2 is made of an insulating material, such as SiO2, SiN, SiC (silicon carbide), AlN (aluminum nitride), or a laminate of two or more of these. The thickness of the protective layer 2 is not particularly limited, and is, for example, 1.0 µm or more and 10 µm or less. The protective layer 2 has a pad opening 21 that penetrates in the z direction. The pad opening 21 exposes the electrode pad portions 312 provided on the multiple individual electrodes 31, respectively.

[0129] As shown in Figs. 36 and 37, the wiring board 5 is disposed adjacent to the head board 1 on the upstream side in the y direction. The wiring board 5 is, for example, a PCB board. As shown in Fig. 36, the wiring board 5 has an elongated rectangular shape with the x direction as the longitudinal direction when viewed in the z direction. A wiring pattern (detailed shape is not shown) is formed on the wiring board 5. As shown in Fig. 39, the wiring pattern includes an individual wiring portion 51 and a common wiring portion 52. As shown in Fig. 37, a connector 59 and a driving IC 7 are mounted on the wiring board 5.

[0130] The connector 59 is used to connect the thermal printhead B10 to a printer (not shown). The connector 59 is attached to the wiring board 5 and connected to the wiring pattern of the wiring board 5, as shown in FIG.

[0131] The driving IC 7 is disposed on the wiring board 5 as shown in Figs. 36 and 37. The driving IC 7 applies a potential to each individual electrode 31 and controls a current flowing through each heat generating portion 41. As shown in Fig. 36, in this embodiment, a plurality of driving ICs 7 are mounted on the wiring board 5. The plurality of driving ICs 7 are disposed at intervals in the x direction. The plurality of driving ICs 7 are disposed such that, for example, one driving IC 7 is assigned to two individual chips 10A adjacent in the x direction.

[0132] 39, the driving IC 7 has a plurality of pad portions 71. The plurality of pad portions 71 are formed in, for example, two rows.

[0133] The multiple wires 61, 62, and 63 shown in FIG. 39 are made of a conductor such as Au. The wire 61 is bonded to a pad portion 71 of the driving IC 7, and is also bonded to an electrode pad portion 312 of the individual electrode 31. This provides electrical continuity between the driving IC 7 and each individual electrode 31. The wire 61 also spans the main portion 323. The wire 62 is bonded to the pad portion 71 of the driving IC 7, and is also bonded to an individual wiring portion 51 of the wiring board 5. This provides electrical continuity between the driving IC 7 and the connector 59 via the individual wiring portion 51. The wire 63 is bonded to the common electrode 32 (main portion 323), and is also bonded to a common wiring portion 52 of the wiring board 5. This provides electrical continuity between the common electrode 32 and the common wiring portion 52.

[0134] A print signal, a control signal, and a voltage to be supplied to the plurality of heat generating units 41 are input to the driving IC 7 from the outside via a connector 59. The plurality of heat generating units 41 are individually energized in accordance with the print signal and the control signal, thereby selectively generating heat.

[0135] 37 and 38, the resin part 78 is formed so as to straddle the head substrate 1 and the wiring substrate 5. The resin part 78 covers the driving IC 7, the wires 61, 62, and 63, and a part of the protective layer 2, and protects the driving IC 7 and the wires 61, 62, and 63.

[0136] 36 and 37, heat dissipation member 81 supports head substrate 1 (substrate 10, multiple individual chips 10A) and wiring board 5. Heat dissipation member 81 is provided to dissipate some of the heat generated by multiple heat generating parts 41 to the outside. Heat dissipation member 81 is made of a metal such as aluminum.

[0137] 36 and 37, the support member 82 is disposed on the heat dissipation member 81 and is interposed between the head substrate 1 (base material 10, multiple individual chips 10A) and the heat dissipation member 81. In this embodiment, the multiple individual chips 10A are bonded to the support member 82. The support member 82 is made of a plate material with high flatness, such as a Si plate.

[0138] Next, one example of a method for manufacturing the thermal printhead B10 will be described below with reference to Figures 40 to 49. Figures 40 to 45 are cross-sectional views showing one step of the method for manufacturing the thermal printhead B10, and correspond to the partially enlarged view of the cross section shown in Figure 38.

[0139] First, as shown in FIG. 40, a base material 10' is prepared. The base material 10' is made of a Si single crystal semiconductor, for example, a Si wafer. The base material 10' has a main surface 11'. The main surface 11' is approximately flat and faces upward in the z direction. The main surface 11' is a (100) plane.

[0140] Next, as shown in FIG. 41, the protrusions 12 are formed. The protrusions 12 are formed by forming a predetermined mask layer (shown by imaginary lines in FIG. 40 and FIG. 41) on a part of the main surface 11' and performing anisotropic etching on the base material 10'. In the step of forming the protrusions 12, anisotropic etching is performed using, for example, an alkaline aqueous solution. Examples of the alkaline aqueous solution include KOH (potassium hydroxide) and TMAH (tetramethylammonium hydroxide). As a result, as shown in FIG. 41, the base material 10 having the main surface 11 and the protrusions 12 is formed. The main surface 11 is a (100) plane like the main surface 11'. The protrusions 12 have a top surface 121 and a pair of inclined surfaces 122. Each of the pair of inclined surfaces 122 is a (111) plane and is inclined with respect to the main surface 11 and the top surface 121. The inclination angle α1 of each inclined surface 122 is, for example, 54.8 degrees.

[0141] 42, the insulating layer 19 is formed by depositing TEOS-SiO2 using, for example, CVD. The insulating layer 19 covers the main surface 11, the pair of inclined surfaces 122 of the protrusion 12, and the top surface 121.

[0142] 43, a resistor film 4' is formed. The resistor film 4' is formed by forming a thin film of TaN on the insulating layer 19 by sputtering, for example. The resistor film 4' covers the entire surface of the insulating layer 19.

[0143] Next, as shown in FIG. 44, the electrode film 3' is formed. The electrode film 3' is formed by forming a layer made of Cu by, for example, plating or sputtering. The electrode film 3' covers the entire surface of the resistor film 4'. Note that the electrode film 3' may be formed by forming a Ti layer on the resistor film 4' and then forming a Cu layer.

[0144] 45, the electrode film 3' and the resistor film 4' are selectively etched to partially remove the electrode film 3' and the resistor film 4'. This forms the resistor layer 4 separated in the x direction and the electrode layer 3 covering the resistor layer 4 while leaving a plurality of heat generating portions 41. Here, the plurality of heat generating portions 41 are formed on the protrusions 12.

[0145] Next, as shown in FIG. 46, the base material 10 is cut along the x-direction and the y-direction to be divided into a plurality of individual chips 10A (not shown). Here, the base material 10 is cut along a plane C1 perpendicular to the x-direction and a plane C2 perpendicular to the y-direction by laser irradiation to be divided into a plurality of individual chips 10A. More specifically, the base material 10 is divided into the individual chips 10A in a peeled manner by focusing the laser on the inside of the base material 10 made of a Si single crystal semiconductor. In such division into the individual chips 10A by laser irradiation, there is almost no cutting width, almost no cutting waste is generated, and the cut surface is smooth.

[0146] As shown in Figures 47 and 48, in the process of dividing into a plurality of individual chips 10A by laser irradiation, the cutting of the base material 10 on a plane C1 perpendicular to the x direction is performed at a position between a pair of heat generating parts 41 adjacent to each other in the x direction. In the formation of the resistor layer 4 and the electrode layer 3 shown in Figure 45, the resistor layer 4 is formed separately from each other in an area corresponding to each of the plurality of individual chips 10A, and the electrode layer 3 is formed separately from each other in an area corresponding to each of the plurality of individual chips 10A. As a result, the resistor layer 4 and the electrode layer 3 are not formed on the cutting line of the base material 10 (the plane C1 perpendicular to the x direction and the plane C2 perpendicular to the y direction shown in Figures 47 and 48).

[0147] 49, an assembly board 91 is prepared, and a support member 82 and a wiring board 5 are arranged on the assembly board 91. The support member 82 is, for example, a Si plate. The wiring board 5 is, for example, a PCB board. The support member 82 and the wiring board 5 are temporarily fixed to the assembly board 91 via an adhesive tape (not shown).

[0148] Next, as shown in FIG. 50 and FIG. 51, the plurality of chips 10A are arranged on the support member 82 along the x direction, and the back surface of the chip 10A is bonded to the upper surface of the support member 82. The chips 10A are bonded to the support member 82 using, for example, a UV adhesive. As shown in FIG. 51, the plurality of chips 10A are aligned with the wiring board 5 and bonded to the support member 82 so that a pair of chips 10A adjacent in the x direction are in close contact with each other. In a pair of chips 10A adjacent in the x direction, the first side 101 of the chip 10A located on one side in the x direction (one side in the main scanning direction) and the second side 102 of the chip 10A located on the other side in the x direction (the other side in the main scanning direction) are in close contact with each other. In this way, the base material 10 composed of the plurality of chips 10A is arranged on the support member 82. The plurality of heat generating parts 41 arranged on the base material 10 are arranged at a constant pitch in the x direction across all of the plurality of chips 10A.

[0149] Next, the protective layer 2 (not shown) is formed. The protective layer 2 is formed by depositing, for example, SiN on each of the insulating layer 19, the electrode layer 3 and the resistor layer 4 on the base material 10, for example, by using CVD. In addition, the protective layer 2 having pad openings 21 (not shown) is formed in a predetermined region on the base material 10, for example, by using a mask. As a result of the above, the head substrate 1 arranged on the support member 82 is obtained.

[0150] 52, a plurality of driving ICs 7 are mounted on the wiring board 5. Next, a plurality of wires 61, 62, 63 are bonded, and a resin part 78 is formed. Then, the support member 82, head substrate 1, and wiring board 5 are separated from the assembly board 91, and thereafter the head substrate 1 and wiring board 5 are joined to a heat dissipation member 81, and the connector 59 is attached, etc. In this manner, the thermal printhead B10 is manufactured.

[0151] Next, the effects of this embodiment will be described.

[0152] In the thermal printhead B10, the resistor layer 4 and the electrode layer 3 are supported by a substrate 10 made of a Si single crystal semiconductor. The resistor layer 4 includes a plurality of heat generating portions 41 arranged in the x direction (main scanning direction). The substrate 10 is configured with a plurality of individual chips 10A aligned in the x direction (main scanning direction). A plurality of heat generating portions 41 are arranged on each individual chip 10A. The boundary between a pair of adjacent individual chips 10A is located between a pair of heat generating portions 41 adjacent to each other in the x direction (main scanning direction). This allows the heat generating portions 41 to be appropriately arranged along the x direction (main scanning direction) across all of the plurality of individual chips 10A.

[0153] In this structure in which the substrate 10 is composed of a plurality of individual chips 10A, the length of the substrate 10 in the x direction (main scanning direction) can be adjusted by appropriately selecting the number of individual chips 10A. Therefore, it is possible to efficiently manufacture thermal printheads B10 with different printing lengths in the x direction (main scanning direction).

[0154] Figure 53 shows a case where the substrate 10 is composed of a larger number of individual chips 10A than in Figure 36. By using a larger number of individual chips 10A in this way, the length of the substrate 10 in the x direction (main scanning direction) can be appropriately increased. Therefore, it is possible to increase the printing length in the x direction (main scanning direction) without being restricted by the size of the Si wafer that is the material of the substrate 10. Therefore, it is possible to increase the length of the thermal printhead B10 in which Si is used as the substrate 10.

[0155] Figure 54 shows a case where the substrate 10 is composed of a smaller number of individual chips 10A than in Figure 36. By using a smaller number of individual chips 10A, it is possible to easily manufacture a thermal printhead B10 with a short printing length in the x direction (main scanning direction). Furthermore, by preparing individual chips 10A with a small dimension in the x direction, it is possible to set the printing length in the x direction (main scanning direction) more precisely.

[0156] Of the multiple individual chips 10A, in a pair of individual chips 10A adjacent in the x direction (main scanning direction), the first side surface 101 and the second side surface 102 facing each other in the x direction are perpendicular to the x direction. With this configuration, the multiple individual chips 10A are aligned straight along the x direction (main scanning direction). Furthermore, the multiple heat generating parts 41 arranged on the substrate 10 are arranged at a constant pitch in the x direction (main scanning direction) across all of the multiple individual chips 10A. With the thermal printhead B10 configured in this way, it is possible to maintain appropriate print quality.

[0157] In the process of dividing the substrate 10 into a plurality of individual chips 10A during the manufacture of the thermal printhead B10, the substrate 10 is cut by laser irradiation. In the laser irradiation of the substrate 10 made of a Si single crystal semiconductor, the substrate 10 is divided into a plurality of individual chips 10A with almost no cutting width and with smooth cut surfaces by concentrating the laser inside the substrate 10. According to such a manufacturing method of the thermal printhead B10, the dimensional accuracy of the cut surfaces (first side surface 101 and second side surface 102) of the individual chips 10A is high, and the resistor layer 4 (heat generating portion 41) and the electrode layer 3 can be arranged close to the cut surfaces. As a result, the plurality of heat generating portions 41 can be arranged at a constant pitch in the x direction (main scanning direction) across all of the plurality of individual chips 10A.

[0158] The electrode layer 3 supported by the substrate 10 is disposed separately from each other on each of the multiple individual chips 10A. The resistor layer 4 supported by the substrate 10 is disposed separately from each other on each of the multiple individual chips 10A. As a result, the formation areas of the electrode layer 3 and the resistor layer 4 do not straddle the multiple individual chips 10A. With this configuration, it is possible to prevent poor conduction in the conduction paths to the multiple heat generating portions 41.

[0159] The substrate 10 (plurality of individual chips 10A) is joined to a support member 82, and is supported by a heat dissipation member 81 via the support member 82. By making the support member 82 a plate material with high flatness, it is possible to suppress variation in the position of the plurality of individual chips 10A in the z direction (thickness direction), and thus it is possible to suppress variation in the printing quality of the thermal printhead B10.

[0160] The substrate 10 has a protruding portion 12. The protruding portion 12 protrudes from the main surface 11 of the substrate 10 and extends in the x direction (main scanning direction). The protruding portion 12 is disposed on each of the multiple individual chips 10A, and multiple heat generating portions 41 are disposed on the protruding portion 12. With this configuration, the printing medium can be accurately brought into contact with the protruding portion 12 on which the multiple heat generating portions 41 are disposed, and improvement in printing quality can be expected.

[0161] The thermal printhead and the method for manufacturing a thermal printhead according to the second aspect of the present disclosure are not limited to the above-described embodiment. The specific configuration of each part of the thermal printhead and the specific processing of each step of the method for manufacturing a thermal printhead can be freely designed in various ways.

[0162] In the above embodiment, the substrate 10 (each individual chip 10A) has the protrusion 12 protruding from the main surface 11, but the substrate 10 may have a configuration that does not have such a protrusion 12. Also, the substrate 10 may have a configuration in which a heat storage layer is interposed between the substrate 10 and the heat generating portion 41 (resistance layer 4).

[0163] In the above embodiment, the case has been described where the substrate 10 (each individual chip 10A) is supported on the heat dissipation member 81 via the support member 82, but the substrate 10 (each individual chip 10A) may be directly supported on the heat dissipation member 81. FIGS. 55 and 56 show a thermal printhead B20 according to such a modified example. Unlike the thermal printhead B10, the thermal printhead B20 does not include a support member 82. In the thermal printhead B20, a plurality of individual chips 10A (substrate 10) and a wiring board 5 are directly bonded to the heat dissipation member 81.

[0164] The present disclosure is not limited to the embodiment according to the second aspect described above. The specific configuration of each part of the present disclosure can be freely changed in various ways. The embodiment according to the second aspect of the present disclosure includes the configurations described in the following Supplementary Notes 1B to 20B.

[0165] Appendix 1B. A substrate having a main surface facing one side in a thickness direction and made of a Si single crystal semiconductor; a resistor layer supported by the base material and including a plurality of heat generating portions arranged in a main scanning direction; an electrode layer supported by the base material and electrically connected to the resistor layer; the base material is configured to include a plurality of individual chips, each of which has a plurality of heat generating portions arranged thereon and which are aligned in the main scanning direction; A thermal printhead, wherein a boundary between a pair of individual chips adjacent in the main scanning direction is located between a pair of heat generating portions adjacent in the main scanning direction. Appendix 2B. of a pair of individual chips adjacent to each other in the main scanning direction, the individual chip located on one side in the main scanning direction has a first side surface facing the other side in the main scanning direction and perpendicular to the main scanning direction, A thermal printhead as described in Appendix 1B, wherein of a pair of individual chips adjacent in the main scanning direction, the individual chip located on the other side in the main scanning direction faces one side in the main scanning direction and has a second side that is perpendicular to the main scanning direction. Appendix 3B. The thermal printhead according to claim 1B or 2B, wherein the plurality of heat generating portions are arranged at a constant pitch in the main scanning direction across all of the plurality of individual chips. Appendix 4B. The thermal printhead according to any one of Appendixes 1B to 3B, wherein the electrode layer in each of the individual chips includes a common electrode and a plurality of individual electrodes. Appendix 5B. the common electrode has a plurality of common electrode extensions each of which is electrically connected to a pair of heat generating portions adjacent to each other in the main scanning direction and extends in a sub-scanning direction; The thermal printhead according to Appendix 4B, wherein the individual electrodes have individual electrode extensions extending in the sub-scanning direction and in contact with the heat generating portions adjacent to the heat generating portions that are electrically connected to the common electrode extensions. Appendix 6B. The thermal printhead according to claim 5B, wherein the common electrode includes a trunk portion that is connected to each of the common electrode extension portions and extends in the main scanning direction. Appendix 7B. the resistor layer is disposed on the substrate, 6C. The thermal printhead of claim 1B, wherein the electrode layer is disposed on the resistor layer. Appendix 8B. The thermal printhead of any one of Appendixes 1B to 7B, wherein the electrode layers are arranged separately from one another on each of the plurality of individual chips. Appendix 9B. A thermal printhead as described in any one of Appendix 1B to 8B, wherein the resistor layers are arranged separately from each other on each of the plurality of individual chips. Appendix 10B. The thermal printhead according to any one of Appendixes 1B to 9B, further comprising a heat dissipation member supporting the plurality of individual chips. Appendix 11B. a support member interposed between the plurality of individual chips and the heat dissipation member, The thermal printhead of claim 10B, wherein the individual chips are bonded to the support member. Appendix 12B. The thermal printhead according to any one of claims 1B to 11B, further comprising a drive IC for controlling a current flowing through each of the heat generating parts. Appendix 13B. The thermal printhead of claim 12B, further comprising a wire connecting the driving IC and the electrode layer. Appendix 14B. The thermal printhead according to claim 12B or 13B, further comprising a resin part covering the driving IC. Appendix 15B. The thermal printhead of claim 14B, further comprising a wiring substrate on which the driving IC is disposed. Appendix 16B. the base material has a protrusion protruding from the main surface, extending in the main scanning direction, and disposed on each of the plurality of individual chips; The thermal printhead according to any one of Appendixes 1B to 15B, wherein the plurality of heat generating portions are arranged on the convex portion. Appendix 17B. The thermal printhead according to claim 16B, wherein the convex portions of the individual chips overlap each other when viewed in the main scanning direction. Appendix 18B. preparing a substrate made of a Si single crystal semiconductor; forming a resistor film on the substrate; forming an electrode film on the resistor film; a step of partially removing the electrode film and the resistor film to form an electrode layer and a resistor layer including a plurality of heat generating portions arranged in a main scanning direction; cutting the base material along a plane perpendicular to the main scanning direction and a plane perpendicular to a sub-scanning direction by irradiating a laser, thereby dividing the base material into a plurality of individual chips; and arranging the plurality of individual chips on a support so as to be aligned along the main scanning direction, In the step of dividing the substrate into a plurality of individual chips, the substrate is cut between a pair of heat generating portions adjacent to each other in the main scanning direction. Appendix 19B. A method for manufacturing a thermal printhead as described in Appendix 18B, wherein in a process of forming the electrode layer and a resistor layer including a plurality of heat generating portions arranged in a main scanning direction, the resistor layer is formed and arranged separately from one another in areas corresponding to each of the plurality of individual chips, and the electrode layer is arranged separately from one another in areas corresponding to each of the plurality of individual chips. Appendix 20B. The method further includes an etching step of anisotropically etching the base material, the etching step being performed before the step of forming the resistor film, In the etching step, a main surface facing one side in a thickness direction and a convex portion protruding from the main surface are formed in the base material by anisotropic etching; The method for manufacturing a thermal printhead according to claim 18B or 19B, wherein in the step of forming the plurality of heat generating portions, a plurality of heat generating portions are formed on the convex portion.

[0166] [Explanation of symbols according to the second aspect of the embodiment] B10, B20: Thermal print head 1: Head board 10: Substrate 10': Substrate 10A: Individual chip 101: First side 102: Second side 11: Main surface 11': Main surface 12: Convex portion 122: Inclined surface 19: Insulating layer 2: Protective layer 21: Pad opening 3: Electrode layer 3': Electrode film 31: Individual electrode 311: Individual electrode extension part 312: Electrode pad section 32: Common electrode 321: Common electrode extension 322: Branch portion 323: Main body 33: Relay electrode 331: Relay electrode extension 332: Connection portion 4: Resistor layer 4': resistor film 41: heating part 5: wiring board 51: Individual wiring section 52: Common wiring section 59: Connector 61, 62, 63: Wires 7: Driver IC 71: Pad section 78: Resin section 81: Heat dissipation member 82: Support member 91: Assembled board 99: Platen roller

[0167] Next, an embodiment according to the third aspect of the present disclosure will be described with reference to FIGS.

[0168] Patent Document 2 discloses an example of a conventional thermal printhead. In this conventional thermal printhead, a convex portion is formed on the main surface of a substrate, extending in the main scanning direction and protruding from the main surface. As shown in FIG. 6 of Patent Document 2, a plurality of heat generating portions are arranged in the main scanning direction on the convex portion. With this configuration, the print medium can be brought into accurate contact with the heat generating portions, and improvement in print quality can be expected.

[0169] The thermal printhead disclosed in Patent Document 2 can be used, for example, for printing barcodes and two-dimensional codes. To achieve this, the thermal printhead needs to be made even smaller, and there is still room for improvement. Thus, an object of the third aspect of the present disclosure is to provide a thermal printhead that can be made smaller.

[0170] A thermal printhead C10 according to a first embodiment of the third aspect will be described with reference to Figs. 57 to 68. The thermal printhead C10 constitutes a main part of a thermal printer 100 (Fig. 60). The thermal printhead C10 mainly comprises a base material 1, an insulating layer 21, a resistor layer 3, a wiring layer 4, and a protective layer 5. In addition to these, the thermal printhead C10 comprises a first substrate 61, a second substrate 62, a first interconnection 63, a plurality of second interconnection 64, a plurality of driving elements 65, and a heat dissipation member 66. In Figs. 57 to 59, the protective layer 5 is shown through for ease of understanding. In Fig. 63, the insulating layer 21, the resistor layer 3, the wiring layer 4, the first substrate 61, the second substrate 62, and the second interconnection 64 are further shown through for ease of understanding (see Fig. 57). In Fig. 63, the first substrate 61 and the second substrate 62 are respectively indicated by imaginary lines (two-dot chain lines). For ease of understanding, in Fig. 65, Fig. 67 and Fig. 68, only the base material 1 and the first interconnection wiring 63 are illustrated.

[0171] In the thermal printhead C10, as shown in Fig. 60, the substrate 1 is joined to a heat dissipation member 66. The substrate 1 supports a first substrate 61 and a second substrate 62. A plurality of heat generating portions 31 (described later) which form part of the resistor layer 3 and are arranged in the x direction are formed on the substrate 1. The plurality of heat generating portions 31 are selectively heated by a plurality of drive elements 65 mounted on the second substrate 62. The plurality of drive elements 65 are driven in accordance with a print signal transmitted from the outside via a connector (not shown) mounted on the first substrate 61.

[0172] As shown in FIG. 60, the thermal printer 100 includes a thermal printhead C10 and a platen roller 69. In the thermal printer 100, the platen roller 69 is configured to feed a recording medium 68 such as thermal paper. With the platen roller 69 pressing the recording medium 68 against the multiple heat generating parts 31, the multiple heat generating parts 31 print on the recording medium 68. In the thermal printer 100, other mechanisms (non-roller-shaped mechanisms) can be used instead of the platen roller 69. For example, such mechanisms include those having a flat pressing surface. The "flat surface" includes a curved surface having a sufficiently small curvature. In this disclosure, the roller-shaped mechanism and other mechanisms are collectively referred to as a "platen."

[0173] The substrate 1 has a strip shape extending along the x direction as shown in Fig. 57. The substrate 1 is made of a semiconductor material. The semiconductor material is, for example, a single crystal material of silicon (Si), but the present disclosure is not limited thereto.

[0174] As shown in Fig. 61, the substrate 1 has a main surface 11 and a back surface 15. The main surface 11 and the back surface 15 are spaced apart from each other in the z direction. The main surface 11 and the back surface 15 face opposite each other in the z direction. The main surface 11 and the back surface 15 of the substrate 1 both have Miller indices of (100). As shown in Fig. 60, in the thermal printhead C10, the main surface 11 faces the platen roller 69, and the back surface 15 faces the heat dissipation member 66.

[0175] As shown in Fig. 61, the base material 1 has a protrusion 12. The protrusion 12 protrudes in the z direction from the main surface 11. As shown in Fig. 57, the protrusion 12 extends long along the x direction.

[0176] As shown in FIG. 62, the protrusion 12 has a top surface 121 and a pair of inclined surfaces 122. The top surface 121 is located away from the main surface 11 in the z direction and is parallel to the main surface 11. The pair of inclined surfaces 122 are located away from each other in the y direction. The pair of inclined surfaces 122 are connected to the top surface 121 and the main surface 11. The pair of inclined surfaces 122 are inclined with respect to the main surface 11 so as to approach each other from the main surface 11 to the top surface 121. The inclination angles α of the pair of inclined surfaces 122 with respect to the main surface 11 are equal to each other.

[0177] 57, 63, and 64, the substrate 1 has a pair of end faces 13 and a first surface 14. The pair of end faces 13 face opposite each other in the x direction and are connected to the rear surface 15. The first surface 14 is located between at least one of the pair of end faces 13 and the protrusion 12 in the x direction. In the thermal printhead C10, the first surface 14 includes a pair of separation regions 14A located on both sides of the protrusion 12. The surface roughness of the first surface 14 is greater than the surface roughness of the main surface 11.

[0178] As shown in Fig. 64, the first surface 14 is located closer to the main surface 11 in the z direction than the top surface 121 of the protrusion 12. Therefore, as shown in Fig. 65, the distance h1 in the z direction from the main surface 11 to the first surface 14 is smaller than the distance h2 in the z direction from the first surface 14 to the top surface 121. The first surface 14 is located between the main surface 11 and the top surface 121 in the z direction. Therefore, the first surface 14 protrudes from the main surface 11 in the z direction by the distance h1. The width b of the first surface 14 (the dimension in the y direction) is smaller than the width B of the lowest part of the protrusion 12 (the dimension in the y direction of the lowest part of the protrusion 12).

[0179] Figures 67 and 68 show thermal printheads C11 and C12 which are modifications of thermal printhead C10. In each of thermal printheads C11 and C12, the configuration of the first surface 14 differs from the configuration of thermal printhead C10 (see Figure 65).

[0180] 67, in a thermal printhead C11, the first surface 14 is flush with the main surface 11. The width b of the first surface 14 is the same as the width B of the lowermost portion of the protrusion 12.

[0181] 68, in the thermal printhead C12, the first surface 14 is located between the main surface 11 and the back surface 15 in the z direction. Therefore, the first surface 14 is recessed from the main surface 11 in the z direction and reaches both ends in the y direction of the substrate 1. The width b of the first surface 14 is larger than the width B of the lowermost part of the protrusion 12 and is equal to the dimension of the substrate 1 in the y direction.

[0182] The configurations of the first surface 14 of thermal printhead C10, thermal printhead C11, and thermal printhead C12 are due to differences in the removal depth (dimension in the z direction) of the protrusions 12. In a manufacturing method for thermal printhead C10 described below, the first surface 14 is formed by removing at least a part of both ends in the y direction of the protrusions 12 (see Figures 71 to 73). The thermal printhead C10 is a case in which the removal depth of the protrusions 12 is the shallowest. On the other hand, the thermal printhead C12 is a case in which the removal depth of the protrusions 12 is the deepest.

[0183] 63 and 66, a plurality of linear scratches 141 each extending along the y direction are formed on the first surface 14. In the thermal printhead C10, at least any of the plurality of linear scratches 141 includes a portion that protrudes from the main surface 11 (see FIG. 66) in the z direction.

[0184] As shown in FIG. 62, the insulating layer 21 covers the main surface 11 and the protrusions 12 of the substrate 1. The insulating layer 21 electrically insulates the substrate 1 from the resistor layer 3 and the wiring layer 4. The insulating layer 21 is made of silicon dioxide (SiO2) using tetraethyl orthosilicate (TEOS) as a raw material, for example. An example of the thickness of the insulating layer 21 is 1 μm or more and 15 μm or less. As shown in FIG. 64, the insulating layer 21 also covers the first surface 14 of the substrate 1.

[0185] The resistor layer 3 is formed on the main surface 11 and the protrusions 12 of the substrate 1, as shown in Fig. 61 and Fig. 62. The resistor layer 3 is in contact with the insulating layer 21. Thus, in the thermal printhead C10, the insulating layer 21 is sandwiched between the substrate 1 and the resistor layer 3. The resistor layer 3 is made of, for example, tantalum nitride (TaN). An example of the thickness of the resistor layer 3 is not less than 0.02 µm and not more than 0.1 µm.

[0186] As shown in FIG. 58, FIG. 59, and FIG. 62, the resistor layer 3 includes a plurality of heat generating portions 31. In the resistor layer 3, the plurality of heat generating portions 31 are exposed from the wiring layer 4. When the plurality of heat generating portions 31 are selectively energized from the wiring layer 4, the plurality of heat generating portions 31 locally heat the recording medium 68. The plurality of heat generating portions 31 are arranged side by side along the x direction. Of the plurality of heat generating portions 31, two adjacent heat generating portions 31 in the x direction are positioned apart from each other. In the thermal printhead C10, the plurality of heat generating portions 31 are formed above the top surface 121 of the protruding portion 12 of the substrate 1. Therefore, when viewed along the z direction, the plurality of heat generating portions 31 overlap the top surface 121. As shown in FIG. 60, in the thermal printer 100, the plurality of heat generating portions 31 face the platen roller 69.

[0187] The wiring layer 4 is formed in contact with the resistor layer 3 as shown in FIG. 61 and FIG. 62. In the thermal printhead C10, the wiring layer 4 is formed on the resistor layer 3. The wiring layer 4 forms a conductive path for passing electricity to the multiple heat generating parts 31 of the resistor layer 3. The electrical resistivity of the wiring layer 4 is smaller than that of the resistor layer 3. The wiring layer 4 is a metal layer made of, for example, copper (Cu). An example of the thickness of the wiring layer 4 is 0.3 μm or more and 2.0 μm or less. Alternatively, the wiring layer 4 may be configured to be made of two metal layers, a titanium (Ti) layer laminated on the resistor layer 3 and a copper layer laminated on the titanium layer. In this case, an example of the thickness of the titanium layer is 0.1 μm or more and 0.2 μm or less.

[0188] As shown in Fig. 58, the wiring layer 4 includes a common wiring 41 and multiple individual wirings 42. The common wiring 41 is located on one side in the y direction (downstream side) of the multiple heat generating portions 31 of the resistor layer 3. The multiple individual wirings 42 are located on the other side in the y direction (upstream side) of the multiple heat generating portions 31. As shown in Fig. 59, when viewed along the z direction, multiple regions of the resistor layer 3 sandwiched between the common wiring 41 and the multiple individual wirings 42 are the multiple heat generating portions 31.

[0189] As shown in FIG. 58 and FIG. 59, the common wiring 41 has a base 411 and a plurality of extending portions 412. In the y direction, the base 411 is located along the downstream periphery of the main surface 11 of the substrate 1. The base 411 is in the form of a strip extending along the x direction. Each of the extending portions 412 is in the form of a strip extending from an end of the base 411 facing the protruding portion 12 of the substrate 1 in the y direction toward the plurality of heat generating portions 31. The extending portions 412 are arranged side by side along the x direction. A portion of each of the extending portions 412 is formed on one of a pair of inclined surfaces 122 of the substrate 1 that is located on one side (downstream side) in the y direction. Therefore, a portion of the common wiring 41 is formed on the inclined surface 122 that is located on one side of the pair of inclined surfaces 122 in the y direction. In the common wiring 41 , a current flows from the base portion 411 through the plurality of extending portions 412 to the plurality of heat generating portions 31 .

[0190] As shown in FIG. 58 and FIG. 59, each of the multiple individual wirings 42 is a strip extending from the upstream periphery of the main surface 11 of the base material 1 toward the multiple heat generating parts 31. The multiple individual wirings 42 are arranged side by side along the x direction. A part of each of the multiple individual wirings 42 is formed on the inclined surface 122 located on the other side (upstream side) in the y direction out of a pair of inclined surfaces 122 of the base material 1. In each of the multiple individual wirings 42, a current flows from one of the multiple heat generating parts 31 toward the upstream side. When viewed along the z direction, each of the multiple heat generating parts 31 is sandwiched between one of the multiple individual wirings 42 and one of the multiple extension parts 412 of the common wiring 41. The configurations of the wiring layer 4 and the multiple heat generating parts 31 shown in FIG. 58 and FIG. 59 are examples. The configurations of the wiring layer 4 and the multiple heat generating parts 31 in the present disclosure are not limited to the configurations shown in FIG. 58 and FIG. 59.

[0191] As shown in FIG. 61, the protective layer 5 covers the heat generating parts 31 of the resistor layer 3 and the wiring layer 4. The protective layer 5 has electrical insulation properties. The protective layer 5 contains silicon. The protective layer 5 is made of, for example, silicon dioxide, silicon nitride (Si3N4), or silicon carbide (SiC). Alternatively, the protective layer 5 may be a laminate made of a plurality of types of these materials. An example of the thickness of the protective layer 5 is 1.0 μm or more and 10 μm or less. In the thermal printer 100, the recording medium 68 is pressed against the area of ​​the protective layer 5 that covers the heat generating parts 31 by the platen roller 69 shown in FIG. 60. As shown in FIG. 64, the protective layer 5 also covers the area of ​​the insulating layer 21 that covers the first surface 14 of the substrate 1.

[0192] As shown in FIG. 61, the protective layer 5 has a first opening 51 and a second opening 52. Each of the first opening 51 and the second opening 52 is in a strip shape extending along the x direction. Each of the first opening 51 and the second opening 52 penetrates the protective layer 5 in the z direction. The first opening 51 is located on the downstream side. The first opening 51 is formed up to the most downstream side of the substrate 1 (referring to the left end of the substrate 1 in FIG. 61). Alternatively, a configuration may be used in which a region of the protective layer 5 is formed that is located on the most downstream side of the substrate 1 with respect to the first opening 51 and extends in a strip shape along the x direction. The base 411 of the common wiring 41 is exposed from the first opening 51. The second opening 52 is located on the upstream side. The second opening 52 is formed up to the most upstream side of the substrate 1 (referring to the right end of the substrate 1 in FIG. 61). Alternatively, a configuration may be used in which a region of the protective layer 5 is formed that is located on the most upstream side of the substrate 1 with respect to the second opening 52 and extends in a strip shape along the x direction. A portion of each of the plurality of individual wirings 42 is exposed from the second opening 52 .

[0193] As shown in FIG. 60, the first substrate 61 is supported by the downstream side of the substrate 1 and the heat dissipation member 66. As shown in FIG. 60, the second substrate 62 is supported by the upstream side of the substrate 1 and the first substrate 61. Each of the first substrate 61 and the second substrate 62 is, for example, an FPC (Flexible Printed Circuits) and has flexibility. As shown in FIG. 1, as viewed along the z direction, each of the first substrate 61 and the second substrate 62 is rectangular with the x direction as the long side direction. As viewed along the z direction, the area of ​​the first substrate 61 is larger than the area of ​​the second substrate 62. The first substrate 61 and the second substrate 62 may be a single substrate integrated with each other instead of two substrates as in the thermal printhead C10.

[0194] As shown in FIG. 1 and FIG. 60, the first substrate 61 has an inner surface 611, an outer surface 612, and an opening 613. The inner surface 611 and the outer surface 612 face opposite each other in the z direction. The inner surface 611 faces the heat dissipation member 66. The outer surface 612 faces the platen roller 69. The opening 613 penetrates the first substrate 61 in the z direction. The opening 613 is located on the upstream side of the base material 1. The opening 613 is a space in which a plurality of driving elements 65 are accommodated. As shown in FIG. 60, the second substrate 62 is supported by the outer surface 612 of the first substrate 61. The second substrate 62 has a mounting surface 621. The mounting surface 621 faces the same side as the inner surface 611 in the z direction. A part of the mounting surface 621 is exposed from the opening 613.

[0195] As shown in FIG. 61, the first interconnection wiring 63 is disposed on the inner surface 611 of the first substrate 61. As shown in FIG. 1, the first interconnection wiring 63 has a first wiring portion 631 and a pair of second wiring portions 632. The first wiring portion 631 extends along the x direction. An upstream end of the first wiring portion 631 is connected to a base portion 411 of the common wiring 41 formed on the main surface 11 of the base material 1. This connection is made by using a conductive bonding material such as solder. As a result, the first interconnection wiring 63 is electrically connected to the common wiring 41. The pair of second wiring portions 632 are connected to both ends of the first wiring portion 631 in the x direction. Each of the pair of second wiring portions 632 extends from the first wiring portion 631 toward the upstream side. As shown in FIG. 63 and FIG. 65, the pair of second wiring portions 632 individually straddle a pair of spaced regions 14A of the first surface 14 of the base material 1. 64, the pair of second wiring portions 632 face the protective layer 5. The pair of second wiring portions 632 are connected to a connector mounted on the first substrate 61. As a result, power is supplied to the common wiring 41 from the connector.

[0196] 60, a region of the first substrate 61 located upstream of the protrusion 12 is located closer to the rear surface 15 of the base material 1 in the z direction than a region of the first substrate 61 located downstream of the protrusion 12. A pair of second wiring portions 632 (see FIG. 57) arranged on the first substrate 61 are flexible together with the first substrate 61. This allows the position in the z direction of each of the pair of second wiring portions 632 to change from the downstream side to the upstream side so as to approach the rear surface 15 in a portion that straddles one of the pair of spaced regions 14A of the first surface 14 in the y direction.

[0197] As shown in FIG. 61, the second interconnections 64 are disposed on the mounting surface 621 of the first substrate 61. As shown in FIG. 58, each of the second interconnections 64 has a pad portion 641 and an extending portion 642. The pad portions 641 of the second interconnections 64 are arranged in a staggered arrangement in the x direction. In detail, the pad portions 641 of the second interconnections 64 include two rows of pad portions 641 arranged in the x direction. In each of the two rows of pad portions 641, the pad portions 641 are arranged side by side along the x direction at an equal pitch p (the pitch p is the center-to-center distance between two adjacent pad portions 641 in the x direction). Of the two rows of pad portions 641, the row of pad portions 641 located on the upstream side and the row of pad portions 641 located on the downstream side are arranged with a shift in the x direction by a distance of 1 / 2 the pitch p. The extension portion 642 is a strip-like shape extending downstream from either end of the pad portion 641 of the multiple second interconnections 64 facing the protrusion 12 of the base material 1 in the y direction. The downstream ends of the extension portions 642 of the multiple second interconnections 64 are individually connected to the multiple individual wires 42. This connection is made by using a conductive bonding material such as solder. As a result, the multiple second interconnections 64 are individually conductive to the multiple individual wires 42.

[0198] As shown in FIG. 1 and FIG. 60, the multiple driving elements 65 are mounted on the mounting surface 621 of the second substrate 62. Each of the multiple driving elements 65 is a semiconductor element in which various circuits are configured. Each of the multiple driving elements 65 is mounted by COF (Clip On Film) on some of the pad parts 641 of the multiple second interconnection wirings 64 and some of the multiple wirings (not shown) that are arranged on the mounting surface 621 and are different from the multiple second interconnection wirings 64. The multiple wirings are connected to a connector. As a result, print signals, control signals, and power for operating the multiple driving elements 65 are input from the connector to the multiple driving elements 65 through the multiple wirings. Based on these electric signals, the multiple driving elements 65 switch the connection between the multiple individual wirings 42 connected through the multiple second interconnection wirings 64 and the ground electrode (not shown) to ON or OFF. In addition, power is supplied from the connector to the multiple heating parts 31 of the resistor layer 3 through the first interconnection wirings 63 arranged on the first substrate 61. As a result, among the plurality of heat generating portions 31, the heat generating portion 31 in which the connection between any one of the plurality of individual wirings 42 and the ground electrode is turned on selectively generates heat.

[0199] As shown in FIG. 60, the heat dissipation member 66 faces the rear surface 15 of the base material 1 and the inner surface 611 of the first substrate 61. The rear surface 15 is joined to the heat dissipation member 66. The first substrate 61 is supported by the heat dissipation member 66. The first substrate 61 is fixed to the heat dissipation member 66 by fastening members such as screws. When the thermal printhead C10 is in use, a portion of the heat generated from the multiple heat generating portions 31 of the resistor layer 3 is conducted to the heat dissipation member 66 via the base material 1. The heat conducted to the heat dissipation member 66 is dissipated to the outside. The heat dissipation member 66 is made of, for example, aluminum (Al).

[0200] An example of a method for manufacturing the thermal printhead C10 will be described with reference to FIGS.

[0201] As shown in FIG. 69 and FIG. 70, a main surface 11 and a protrusion 12 are formed on a substrate 81. Specifically, as shown in FIG. 69, a first mask layer 891 that covers a part of the substrate 81 and a second mask layer 892 that covers the first mask layer 891 are formed. The substrate 81 is made of a semiconductor material. The semiconductor material is, for example, a single crystal material of silicon. The substrate 81 is a silicon wafer. In a direction perpendicular to the z direction, a plurality of regions that correspond to the plurality of substrates 1 are connected together to form the substrate 81. The substrate 81 has a first surface 81A and a second surface 81B. The first surface 81A and the second surface 81B face in opposite directions to each other in the z direction. The first surface 81A and the second surface 81B of the substrate 81 are both planes with Miller indices (100).

[0202] The first mask layer 891 is formed to cover the first surface 81A and the second surface 81B. The first mask layer 891 is made of silicon dioxide. The second mask layer 892 is formed to cover a region of the first mask layer 891 that covers the first surface 81A. The second mask layer 892 is made of silicon nitride. The first mask layer 891 and the second mask layer 892 are formed by a first process described later. As shown in FIG. 69, the first mask layer 891 that covers a part of the first surface 81A and the second mask layer 892 that covers the first mask layer 891 are formed by a second process described later. The first mask layer 891 and the second mask layer 892 that covers the first mask layer 891 have mask openings 893 that penetrate in the z direction.

[0203] In forming the first mask layer 891 and the second mask layer 892, first, a thin film of silicon dioxide is formed by thermal oxidation to cover the first surface 81A and the second surface 81B. Then, a thin film of silicon nitride is formed by thermal CVD (Chemical Vapor Deposition) to cover the region of the first mask layer 891 covering the first surface 81A. This is the first process. Then, in the second process, a part of the region of the thin film of silicon dioxide covering the first surface 81A and a part of the thin film of silicon nitride covering the region are removed by lithography patterning and reactive ion etching (RIE). As a result, as shown in FIG. 69, the first mask layer 891 and the second mask layer 892 are formed, and mask openings 893 are formed in the first mask layer 891 covering a part of the first surface 81A and the second mask layer 892 covering the first mask layer 891.

[0204] As an alternative method for the first step, a technique may be adopted in which a thin film of silicon nitride covering the first surface 81A and the second surface 81B is formed by thermal CVD. In this case, in the second step, lithography patterning and reactive ion etching are used to form a predetermined region on the first surface 81A that is covered by the first mask layer 891, and a mask opening 893 that is a region other than that region where the first surface 81A is exposed.

[0205] Next, as shown in FIG. 70, the main surface 11 and the protrusions 12 are formed on the base material 81. The main surface 11 and the protrusions 12 are formed by wet etching the area of ​​the first surface 81A exposed by the mask opening 893 shown in FIG. 69 using an aqueous solution of potassium hydroxide (KOH). This etching is anisotropic. Finally, the first mask layer 891 and the second mask layer 892 are removed by wet etching using hydrofluoric acid (HF). As a result, the main surface 11 and the protrusions 12 are formed on the base material 81. Furthermore, the second surface 81B of the base material 81 becomes the back surface 15. The area of ​​the first surface 81A covered by the first mask layer 891 and the second mask layer 892 becomes the top surface 121 of the protrusions 12. The inclination angles α of the pair of inclined surfaces 122 of the protrusions 12 with respect to the main surface 11 are equal to each other. This is due to the fact that the protrusions 12 are formed by anisotropic etching.

[0206] Next, as shown in FIG. 71 to FIG. 73, at least one of both ends in the x direction of the convex portion 12 of the base material 81 is removed. In the illustrated example, both ends of the convex portion 12 are removed. As shown in FIG. 71, in this process, a dicing blade 88 rotating around the x direction is pressed against the convex portion 12, thereby removing both ends of the convex portion 12. As shown in FIG. 72, the dicing blade 88 is pressed against the convex portion 12 while shifting its position in the x direction in sequence according to the dimension in the x direction of the convex portion 12 to be removed. In addition, when removing the ends of the convex portion 12, a method can be adopted in which a plurality of notches positioned apart from each other in the x direction are provided in the convex portion 12 by the dicing blade 88, and then the convex portion 12 divided by the plurality of notches is removed by wet etching. Through this process, a first surface 14 is formed on the base material 81 as shown in FIG. 73. A plurality of linear scratches 141 each extending along the y direction are formed on the first surface 14. In the substrate 1, the surface roughness of the first surface 14 is greater than the surface roughness of the main surface 11.

[0207] In the example shown in Fig. 71 and Fig. 72, the thickness (dimension in the x direction) of the dicing blade 88 is constant along the z direction. Alternatively, a dicing blade whose thickness gradually decreases toward the periphery (i.e., toward the main surface 11 of the base material 81 in the z direction) may be used. In this case, the shape of the removed portion of the protrusion 12 (shape viewed along the y direction; see Fig. 71) becomes trapezoidal (the lower base is shorter than the upper base). As a result, the end face facing the x direction of the protrusion 12 shown in Fig. 64 (the end face facing the right in Fig. 64) is inclined downward to the right from the top surface 121 toward the main surface 11.

[0208] 74, an insulating layer 21 is formed to cover the main surface 11 and the protrusions 12 of the base material 81. The insulating layer 21 is formed by laminating a plurality of thin films of silicon dioxide. Each thin film can be formed by plasma CVD using, for example, tetraethyl orthosilicate (TEOS) as a raw material gas.

[0209] Next, as shown in Figs. 75 to 77, a resistor layer 3 and a wiring layer 4 are formed. The resistor layer 3 includes a plurality of heat generating portions 31 arranged in the x direction. The wiring layer 4 is electrically connected to the plurality of heat generating portions 31. The step of forming the wiring layer 4 includes a step of forming a common wiring 41 and a plurality of individual wirings 42. In the substrate 81, the common wiring 41 is located on one side in the y direction with respect to the plurality of heat generating portions 31 of the resistor layer 3 shown in Fig. 77. In the substrate 81, the plurality of individual wirings 42 are located on the other side in the y direction with respect to the plurality of heat generating portions 31 shown in Fig. 77.

[0210] 75, a resistor film 82 is formed on the main surface 11 and the protrusions 12 of a substrate 81. The resistor film 82 is formed so as to cover the entire surface of the insulating layer 21. The resistor film 82 is formed by laminating a thin film of tantalum nitride on the insulating layer 21 by a sputtering method.

[0211] 76, a conductive layer 83 is formed to cover the entire surface of the resistor film 82. The conductive layer 83 is formed by laminating a thin copper film multiple times on the resistor film 82 by a sputtering method. Alternatively, the conductive layer 83 may be formed by laminating a thin titanium film on the resistor film 82 by a sputtering method, and then laminating a thin copper film multiple times on the thin titanium film by a sputtering method.

[0212] Next, as shown in FIG. 77, after lithography patterning is performed on the conductive layer 83, a part of the conductive layer 83 is removed. The removal is performed by wet etching using a mixed solution of sulfuric acid (H2SO4) and hydrogen peroxide (H2O2). As a result, the common wiring 41 and a plurality of individual wirings 42 are formed in contact with the resistor film 82. This completes the formation of the wiring layer 4. Furthermore, the region of the resistor film 82 formed on the top surface 121 of the protrusion 12 of the substrate 81 is exposed from the wiring layer 4. Next, the portion of the resistor film 82 that is unnecessary in the thermal printhead C10 is removed. The removal is performed by reactive ion etching. As a result, the resistor layer 3 is formed on the main surface 11 and the protrusion 12 of the substrate 81. A plurality of heat generating parts 31 are formed on the top surface 121 of the substrate 81.

[0213] 78, a protective layer 5 is formed to cover the heat generating portions 31 of the resistor layer 3 and the wiring layer 4. The protective layer 5 is formed by laminating thin films of silicon nitride by plasma CVD.

[0214] 79, a first opening 51 and a second opening 52 penetrating in the z-direction are formed in the protective layer 5. The first opening 51 and the second opening 52 are formed by removing a portion of the protective layer 5 after lithographic patterning is performed on the protective layer 5. The removal is performed by reactive ion etching. As a result, the base 411 of the common wiring 41 is exposed from the first opening 51. A portion of each of the multiple individual wirings 42 is exposed from the second opening 52.

[0215] Next, the substrate 81 is cut along the x-direction and the y-direction to divide the substrate 81 into individual pieces. This results in the substrate 1 of the thermal printhead C10. A pair of end faces 13 is formed on the substrate 1. Next, as shown in FIG. 80, the second substrate 62 on which the multiple second interconnections 64 are arranged is supported on the first substrate 61 on which the first interconnections 63 are arranged, and then the first wiring portion 631 of the first interconnection 63 is connected to the base portion 411 of the common wiring 41. Also, the multiple second interconnections 64 are individually connected to the multiple individual wirings 42. These two types of connections are made by using a conductive bonding material such as solder. This results in a configuration in which the first substrate 61 and the second substrate 62 are supported on the substrate 1. Next, the multiple driving elements 65 are mounted on the mounting surface 621 of the second substrate 62. Finally, the rear surface 15 of the substrate 1 and the first substrate 61 are bonded to the heat dissipation member 66. Through the above steps, the thermal printhead C10 is obtained.

[0216] Next, the function and effect of the thermal printhead C10 will be described.

[0217] The substrate 1 of the thermal printhead C10 has a main surface 11, a protrusion 12, a pair of end faces 13, and a first surface 14. The first surface 14 is located between at least one of the pair of end faces 13 and the protrusion 12 in the x direction, and is located closer to the main surface 11 than the top surface 121 of the protrusion 12 in the z direction. The thermal printhead C10 includes a connection wiring (first connection wiring 63) that is electrically connected to the wiring layer 4 and that straddles the first surface 14. With this configuration, even if the size of the substrate 1 is reduced, a conductive path for the wiring layer 4 (common wiring 41) can be provided on the substrate 1. In this way, the thermal printhead C10 contributes to miniaturization.

[0218] The first surface 14 of the substrate 1 includes two spaced regions 14A located at both ends of the protrusion 12. The interconnection wiring straddles the spaced region 14A. This allows the thermal printhead C10 to be miniaturized while further increasing the cross-sectional area of ​​the conductive path for the common wiring 41, making it possible to supply greater power to the common wiring 41.

[0219] The thermal printhead C10 further includes a substrate (first substrate 61) on which interconnection wiring is arranged. The interconnection wiring is electrically connected to the common wiring 41. This eliminates the need for a process for forming interconnection wiring on the base material 1 in the manufacture of the thermal printhead C10. Furthermore, because the interconnection wiring is integrated with the substrate, it is possible to prevent the pattern of the interconnection wiring from being broken due to factors such as external force.

[0220] In the thermal printhead C10, a part of the common wiring 41 and a part of each of the multiple individual wirings 42 are formed on one of a pair of inclined surfaces 122 of the protrusion 12. This makes it possible to further reduce the dimension of each of the multiple heat generating parts 31 in the y direction when viewed along the z direction, while further reducing the contact area of ​​the recording medium 68 with the thermal printhead C10. Therefore, it is possible to further improve the quality of printing on the recording medium 68 while suppressing the amount of heat generated in the thermal printhead C10.

[0221] In the substrate 1, the pair of inclined surfaces 122 are inclined with respect to the main surface 11 so as to approach each other from the main surface 11 to the top surface 121. Such a shape of the protrusions 12 is obtained by forming the protrusions 12 on the substrate 81 by anisotropic etching in the manufacturing process of the thermal printhead C10 shown in Fig. 66. This is because the substrate 81 is made of a semiconductor material and the semiconductor material contains a single crystal silicon material.

[0222] The thermal printhead C10 includes a protective layer 5 that covers a plurality of heat generating portions 31 and the wiring layer 4. This allows the heat generating portions 31 and the wiring layer 4 to be protected by the protective layer 5, and also reduces the frictional force of the recording medium 68 against the thermal printhead C10.

[0223] The thermal printhead C10 further includes a heat dissipation member 66. The rear surface 15 of the substrate 1 is joined to the heat dissipation member 66. This allows a portion of the heat generated from the multiple heat generating parts 31 during use of the thermal printhead C10 to be rapidly dissipated to the outside via the substrate 1 and the heat dissipation member 66.

[0224] A thermal printhead C20 according to a second embodiment of the third aspect will be described with reference to Fig. 81. In Fig. 81, elements that are the same as or similar to those in the thermal printhead C10 described above are given the same reference numerals, and duplicated explanations will be omitted. For ease of understanding, Fig. 81 shows the protective layer 5 through which the image is viewed.

[0225] In the thermal printhead C20, the configuration of the first surface 14 of the substrate 1 and the configuration of the first interconnection wiring 63 are different from those of the thermal printhead C10.

[0226] 81, the first surface 14 of the substrate 1 is located between one of the pair of end faces 13 and the protrusion 12 in the x direction. For this reason, in the thermal printhead C20, the first surface 14 does not include a pair of separated regions 14A. As a result, the first connecting wiring 63 has a first wiring portion 631 and a second wiring portion 632. The second wiring portion 632 is connected to only one of both ends of the first wiring portion 631 in the x direction where the first surface 14 is located.

[0227] Next, the function and effect of the thermal printhead C20 will be described.

[0228] The substrate 1 of the thermal printhead C20 has a main surface 11, a protrusion 12, a pair of end faces 13, and a first surface 14. The first surface 14 is located between at least one of the pair of end faces 13 and the protrusion 12 in the x direction, and is located closer to the main surface 11 than the top surface 121 of the protrusion 12 in the z direction. The thermal printhead C20 includes a connection wiring (first connection wiring 63) that is electrically connected to the wiring layer 4 and that straddles the first surface 14. Therefore, the thermal printhead C20 also makes it possible to miniaturize the thermal printhead. Furthermore, the thermal printhead C20 has a configuration in common with the thermal printhead C10, and thereby achieves the same effects as the thermal printhead C10.

[0229] A thermal printhead C30 according to a third embodiment of the third aspect will be described with reference to Figs. 82 and 83. In these figures, elements that are the same as or similar to those of the thermal printhead C10 described above are given the same reference numerals, and duplicated explanations will be omitted. In Fig. 82, for ease of understanding, the protective layer 5 is shown through. In Fig. 83, for ease of understanding, the insulating layer 21, the resistor layer 3, the wiring layer 4 (excluding the base 411 of the common wiring 41), and the multiple second interconnect wirings 64 are also shown through.

[0230] The thermal printhead C30 differs from the thermal printhead C10 in the configuration of the first interconnecting wiring 63 and in that it further includes a third interconnecting wiring 67. Furthermore, the thermal printhead C30 does not include a first substrate 61.

[0231] As shown in FIGS. 82 and 83, the first interconnection 63 includes two regions located apart from each other in the x direction. These two regions are connected to both ends in the x direction of the base 411 of the common interconnection 41, respectively. As a result, the first interconnection 63 is electrically connected to the common interconnection 41. The first interconnection 63 is formed on the main surface 11 of the substrate 1 together with the wiring layer 4. As a result, the first interconnection 63 is made of the same metal layer as the metal layer constituting the wiring layer 4. The first interconnection 63 extends from the base 411 toward the upstream side, and straddles a pair of spaced apart regions 14A on the first surface 14 of the substrate 1.

[0232] As shown in FIGS. 82 and 83, the third interconnection 67 includes two regions located apart from each other in the x direction. The third interconnection 67 is disposed on the mounting surface 621 of the second substrate 62. Each of the two regions of the third interconnection 67 extends along the y direction. The downstream end of the third interconnection 67 is connected to the first interconnection 63. As a result, the third interconnection 67 is electrically connected to the common interconnection 41 via the first interconnection 63. The third interconnection 67 is connected to a connector. Power is supplied to the common interconnection 41 via the connector.

[0233] Next, the function and effect of the thermal printhead C30 will be described.

[0234] The substrate 1 of the thermal printhead C30 has a main surface 11, a protrusion 12, a pair of end faces 13, and a first surface 14. The first surface 14 is located between at least one of the pair of end faces 13 and the protrusion 12 in the x direction, and is located closer to the main surface 11 than the top surface 121 of the protrusion 12 in the z direction. The thermal printhead C30 includes a connection wiring (first connection wiring 63) that is electrically connected to the wiring layer 4 and that straddles the first surface 14. Therefore, the thermal printhead C30 also makes it possible to achieve miniaturization. Furthermore, the thermal printhead C30 has a configuration in common with the thermal printhead C10, and thereby achieves the same effects as the thermal printhead C10.

[0235] In the thermal printhead C30, the interconnections are formed on the main surface 11 of the base material 1 together with the wiring layer 4. This eliminates the need for a substrate (first substrate 61) for arranging the interconnections, making it possible to further reduce the dimension of the thermal printhead C30 in the y direction.

[0236] A thermal printhead C40 according to a fourth embodiment of the third aspect will be described with reference to Figures 84 and 85. In these figures, elements that are the same as or similar to those of the thermal printhead C10 described above are given the same reference numerals, and duplicated descriptions will be omitted.

[0237] In the thermal printhead C40, the configuration of the protrusions 12 of the substrate 1 and the configuration of the plurality of heat generating portions 31 of the resistor layer 3 are different from those of the thermal printhead C10.

[0238] As shown in Figs. 84 and 85, each of the pair of inclined surfaces 122 of the protrusion 12 includes a first inclined surface 122A and a second inclined surface 122B. The first inclined surface 122A is connected to the main surface 11 of the substrate 1. The second inclined surface 122B is connected to the top surface 121 of the protrusion 12 and the first inclined surface 122A. In each of the pair of inclined surfaces 122, the inclination angle α2 of the second inclined surface 122B with respect to the main surface 11 is smaller than the inclination angle α1 of the first inclined surface 122A with respect to the main surface 11. Such a pair of inclined surfaces 122 is formed by performing wet etching using a tetramethylammonium hydroxide (TMAH) aqueous solution on the boundary 123 between the top surface 121 and the pair of inclined surfaces 122 and their vicinity between the process shown in Fig. 70 and the process shown in Fig. 74 in the manufacture of the thermal printhead C10.

[0239] As shown in FIG. 85, the heat generating parts 31 of the resistor layer 3 are formed in the following manner. First, the heat generating parts 31 are formed on the top surface 121 of the protrusion 12. Second, the heat generating parts 31 are formed across the top surface 121 and the second inclined surface 122B of the inclined surface 122 located on the downstream side of the pair of inclined surfaces 122 of the protrusion 12. Third, the heat generating parts 31 are formed across the top surface 121 and the second inclined surface 122B of the inclined surface 122 located on the downstream side of the pair of inclined surfaces 122 and the first inclined surface 122A of the inclined surface 122. Fourth, the heat generating parts 31 are formed across the second inclined surface 122B of the inclined surface 122 located on the downstream side of the pair of inclined surfaces 122 and the first inclined surface 122A of the inclined surface 122. In summary, the heat generating portions 31 are formed on the top surface 121 and / or on one of the pair of inclined surfaces 122 .

[0240] Next, the function and effect of the thermal printhead C40 will be described.

[0241] The substrate 1 of the thermal printhead C40 has a main surface 11, a protrusion 12, a pair of end faces 13, and a first surface 14. The first surface 14 is located between at least one of the pair of end faces 13 and the protrusion 12 in the x direction, and is located closer to the main surface 11 than the top surface 121 of the protrusion 12 in the z direction. The thermal printhead C40 includes a connection wiring (first connection wiring 63) that is electrically connected to the wiring layer 4 and that straddles the first surface 14. Therefore, the thermal printhead C40 also makes it possible to achieve miniaturization. Furthermore, the thermal printhead C40 has a configuration in common with the thermal printhead C10, and thereby achieves the same effects as the thermal printhead C10.

[0242] In the thermal printhead C40, each of the pair of inclined surfaces 122 of the protrusion 12 includes a first inclined surface 122A and a second inclined surface 122B. The first inclined surface 122A is connected to the main surface 11 of the substrate 1. The second inclined surface 122B is connected to the top surface 121 of the protrusion 12 and the first inclined surface 122A. In each of the pair of inclined surfaces 122, the inclination angle α2 of the second inclined surface 122B with respect to the main surface 11 is smaller than the inclination angle α1 of the first inclined surface 122A with respect to the main surface 11. By adopting this configuration, the shape of a part of the wiring layer 4 formed along the protrusion 12 becomes smoother. In addition, the occurrence of defects and breaks in the wiring pattern is suppressed in the wiring layer 4 formed along the protrusion 12.

[0243] A thermal printhead C50 according to a fifth embodiment of the third aspect will be described with reference to Figures 86 and 87. In these figures, elements that are the same as or similar to those of the thermal printhead C10 described above are given the same reference numerals, and duplicated explanations will be omitted. Here, the cross-sectional position of Figure 86 is the same as that of Figure 61, which shows the main part of the thermal printhead C10.

[0244] The thermal printhead C50 differs from the thermal printhead C10 in that it further comprises a glaze layer 22.

[0245] As shown in Figs. 86 and 87, the glaze layer 22 is located between the top surface 121 of the protrusion 12 and the insulating layer 21. The glaze layer 22 is made of a material containing glass, for example, amorphous glass. The linear expansion coefficient of the glaze layer 22 is the same as or substantially the same as the linear expansion coefficient of the substrate 1. As shown in Fig. 87, the glaze layer 22 bulges in the z direction toward the side toward which the top surface 121 faces. The dimension H of the glaze layer 22 in the z direction is largest at the center of the glaze layer 22 in the y direction.

[0246] Next, an example of a method for manufacturing the thermal printhead C50 will be described with reference to FIG.

[0247] As in the case of the thermal printhead C10, at least one of both ends in the x direction of the protrusions 12 of the substrate 81 is removed (FIGS. 71 to 73), and then, as shown in FIG. 88, the glaze layer 22 is formed in contact with the top surface 121 of the protrusions 12 of the substrate 81. The glaze layer 22 is formed by supplying a fluid glaze material to the top surface 121 and then baking the glaze material. The glaze material is supplied, for example, by discharging the glaze material from a dispenser. The glaze material includes glass such as amorphous glass. The glaze material may be applied multiple times. Another example of a method for supplying the glaze material is a method of printing the glaze material on the top surface 121 using a screen. After the glaze layer 22 is formed, as in the case of the thermal printhead C10 described above, the thermal printhead C50 is obtained through the same steps as those shown in FIG. 74 to FIG. 80.

[0248] Next, the function and effect of the thermal printhead C50 will be described.

[0249] The substrate 1 of the thermal printhead C50 has a main surface 11, a protrusion 12, a pair of end faces 13, and a first surface 14. The first surface 14 is located between at least one of the pair of end faces 13 and the protrusion 12 in the x direction, and is located closer to the main surface 11 than the top surface 121 of the protrusion 12 in the z direction. The thermal printhead C50 includes interconnects (first interconnects 63) that are electrically connected to the wiring layer 4 and span the first surface 14. Therefore, the thermal printhead C50 also makes it possible to achieve miniaturization.

[0250] The thermal printhead C50 further includes a glaze layer 22 located between the top surfaces 121 of the protrusions 12 and the insulating layer 21. The glaze layer 22 bulges in the z direction toward the side toward which the top surfaces 121 face. This configuration makes it possible to reduce the contact area of ​​the thermal printhead C50 and the recording medium 68 while suppressing the size of the protrusions 12. Furthermore, the glaze layer 22 has the effect of storing heat generated by the multiple heat generating parts 31. Therefore, the thermal printhead C50 can improve the quality of printing on the recording medium 68 by the multiple heat generating parts 31 while improving printing energy efficiency.

[0251] The present disclosure is not limited to the embodiment according to the third aspect described above. The specific configuration of each part of the present disclosure can be freely changed in various ways. The embodiment according to the third aspect of the present disclosure includes the configurations described in the following Supplementary Notes 1C to 21C.

[0252] Appendix 1C. A substrate having a main surface facing a thickness direction, a pair of end surfaces spaced apart from each other in a main scanning direction, and a protrusion protruding from the main surface in the thickness direction and extending along the main scanning direction; a resistor layer including a plurality of heat generating portions arranged in the main scanning direction and formed on the main surface and the protruding portions; a wiring layer in contact with the resistor layer and electrically connected to the heat generating portions; and a connecting wiring; The protrusion has a top surface parallel to the main surface, the base material has a first surface located between at least one of the pair of end surfaces and the convex portion in the main scanning direction and located closer to the main surface than the top surface in the thickness direction; The thermal printhead, wherein the interconnection wiring is configured to be conductive to the wiring layer and to straddle the first surface. Appendix 2C. the protrusion has a pair of inclined surfaces that are connected to the top surface and the main surface and are spaced apart from each other in the sub-scanning direction, The thermal printhead of claim 1C, wherein the plurality of heat generating portions overlap the top surface when viewed along the thickness direction. Appendix 3C. the wiring layer includes a common wiring and a plurality of individual wirings; the common wiring is located on one side of the plurality of heat generating portions in the sub-scanning direction, the individual wirings are located on the other side of the heat generating portions in the sub-scanning direction, a portion of the common wiring is formed on one of the pair of inclined surfaces that is located on the one side in the sub-scanning direction, a portion of each of the plurality of individual wirings is formed on one of the pair of inclined surfaces that is located on the other side in the sub-scanning direction, The thermal printhead of claim 2C, wherein the interconnection wiring is electrically connected to the common wiring. Appendix 4C. the first surface includes a pair of spaced apart regions located at both ends of the protrusion in the main scanning direction, The thermal printhead of claim 3C, wherein the interconnection lines span each of the pair of spaced apart regions. Appendix 5C. The thermal printhead of claim 3C or 4C, wherein the first surface has a surface roughness greater than a surface roughness of the main surface. Appendix 6C. A linear scratch extending along the sub-scanning direction is formed on the first surface, The thermal printhead of claim 5C, wherein the linear scratches include portions protruding from the main surface in the thickness direction. Appendix 7C. The thermal printhead according to any one of Appendixes 3C to 6C, wherein the pair of inclined surfaces are inclined so as to approach each other from the main surface to the top surface. Appendix 8C. each of the pair of inclined surfaces includes a first inclined surface connected to the main surface and a second inclined surface connected to the top surface and the first inclined surface; The thermal printhead of claim 7C, wherein an angle of inclination of the second inclined surface with respect to the main surface is smaller than an angle of inclination of the first inclined surface with respect to the main surface. Appendix 9C. the substrate is made of a semiconductor material; A thermal printhead as described in any one of Appendixes 3C to 8C, wherein the semiconductor material is a single crystal material of silicon. Appendix 10C. further comprising an insulating layer covering the main surface and the protrusion, The thermal printhead of claim 9C, wherein the resistor layer is in contact with the insulating layer. Appendix 11C. a glaze layer located between the top surface and the insulating layer; The thermal printhead of claim 10, wherein the glaze layer bulges in the thickness direction in the direction in which the top surface faces. Appendix 12C. The thermal printhead of claim 11C, wherein the glaze layer is made of a material including glass. Appendix 13C. The thermal printhead of any one of Appendixes 3C to 12C, further comprising a protective layer covering the plurality of heat generating portions and the wiring layer. Appendix 14C. a portion of the protective layer is located on the first surface; The thermal printhead of claim 13C, wherein the interconnection wiring faces the protective layer. Appendix 15C. Further comprising a substrate on which the interconnection wiring is disposed, The thermal printhead according to any one of Appendixes 3C to 14C, wherein the interconnection wiring is connected to the common wiring. Appendix 16C. Further comprising a heat dissipation member, the substrate has a back surface facing the opposite side to the main surface in the thickness direction, The back surface is joined to the heat dissipation member, The thermal printhead of claim 15C, wherein the substrate is supported by the heat dissipation member. Appendix 17C. A thermal printhead according to any one of appendices 3C to 16C; a platen roller disposed opposite the plurality of heat generating portions. Appendix 18C. A substrate preparation process for forming a substrate having a main surface facing a thickness direction and a protrusion protruding from the main surface in the thickness direction and extending along a main scanning direction; a removing step of removing at least one of both ends of the protrusion in the main scanning direction; forming a resistor layer including a plurality of heat generating portions arranged in the main scanning direction on the main surface and the protruding portion; forming a wiring layer that is electrically connected to the plurality of heat generating portions in contact with the resistor layer; A method for manufacturing a thermal printhead comprising: Appendix 19C. The method for manufacturing a thermal printhead according to claim 18C, wherein the removing step includes pressing a dicing blade rotating about an axis parallel to the main scanning direction against the convex portion. Appendix 20C. the substrate is made of a semiconductor material; The method of manufacturing a thermal printhead described in Appendix 18C or 19C, wherein the semiconductor material is a single crystal material of silicon. Appendix 21C. The method for manufacturing a thermal printhead described in Appendix 20C, wherein the base material preparation step includes performing anisotropic etching to form the main surface and the convex portion.

[0253] [Explanation of symbols according to the embodiment of the third aspect] C10, C20, C30, C40, C50: Thermal print head 1: Base material 11: Main surface 12: Convex portion 121: Top surface 122: Inclined surface 122A: First inclined surface 122B: Second slope 123: Boundary 13: End surface 14: First surface 14A: Separated area 141: Linear trace 15: Back surface 21: Insulating layer 22: Glaze layer 3: Resistor layer 31: Heat generating part 4: Wiring layer 41: Common wiring 411: Base 412: Extension part 42: Individual wiring 5: Protective layer 51: First opening 52: Second opening 61: First substrate 611: Inner surface 612: External surface 613: Opening 62: Second board 621: Mounting surface 63: First connecting wiring 631: First wiring section 632: Second wiring section 64: Second interconnection wiring 641: Pad section 642: Extension portion 65: Driving element 66: Heat dissipation member 67: Third interconnection wiring 68: Recording medium 69: Platen roller 81: Base material 81A: First surface 81B: Second surface 82: Resistor film 83: Conductive layer 88: Dicing blade 891: First mask layer 892: second mask layer 893: mask opening

[0254] Next, an embodiment according to the fourth aspect of the present disclosure will be described with reference to FIGS.

[0255] As described above, in the thermal printhead disclosed in Patent Document 2, a convex portion extending in the main scanning direction and protruding from the main surface is formed on the main surface of the substrate. In addition, a plurality of heat generating parts are arranged on the convex portion along the main scanning direction. In manufacturing such a thermal printhead, it takes a relatively long time to form the convex portions. Therefore, an object of a fourth aspect of the present disclosure is to provide a thermal printhead that can improve printing quality and manufacturing efficiency.

[0256] A thermal printhead D10 according to a first embodiment of the fourth aspect will be described with reference to Figs. 89 to 94. The thermal printhead D10 mainly includes a substrate 1, an insulating layer 2, a resistor layer 3, a wiring layer 4, a protective layer 5, and a covering layer 6. In addition to these, the thermal printhead D10 also includes a wiring board 71, a heat dissipation member 72, a plurality of driving elements 73, a plurality of first wires 74, a plurality of second wires 75, a sealing resin 76, and a connector 77. In Fig. 89, for ease of understanding, the protective layer 5 and the covering layer 6 are shown through, and the first wires 74, the second wires 75, and the sealing resin 76 are omitted. In Figs. 90 and 91, for ease of understanding, the protective layer 5 and the covering layer 6 are shown through.

[0257] As shown in FIG. 92, the substrate 1 of the thermal printhead D10 is joined to a heat dissipation member 72. The wiring substrate 71 is located next to the substrate 1 in the y direction. The wiring substrate 71 is fixed to the heat dissipation member 72, just like the substrate 1. A plurality of heat generating portions 31 (described later) that form part of the resistor layer 3 and are arranged in the x direction are formed on the substrate 1. The plurality of heat generating portions 31 selectively generate heat by a plurality of drive elements 73 mounted on the wiring substrate 71. The plurality of drive elements 73 are driven in accordance with a print signal transmitted from the outside via a connector 77.

[0258] As shown in Fig. 92, the thermal printhead D10 constitutes a part of a thermal printer 100. As another element, the thermal printer 100 includes a platen roller 79. The platen roller 79 is configured to feed a recording medium 78 such as thermal paper. Printing is performed on the recording medium 78 while the platen roller 79 presses the recording medium 78 against a plurality of heat generating elements 31. As described in the third aspect, other mechanisms that are not roller-shaped (for example, a flat or substantially flat pressing surface) may be used instead of the platen roller 79.

[0259] The substrate 1 has a strip shape extending in the x-direction as shown in Fig. 89. The substrate 1 is made of a semiconductor material. The semiconductor material is, for example, a single crystal material of silicon (Si).

[0260] As shown in Fig. 93, the substrate 1 has a main surface 11, a back surface 12, an end surface 13, and an intermediate surface 14. The main surface 11 and the back surface 12 face in opposite directions in the z direction. The main surface 11 and the back surface 12 of the substrate 1 are both surfaces with Miller indices (100). The main surface 11 and the back surface 12 face in opposite directions in the z direction. As shown in Fig. 92, in the thermal printhead D10, the back surface 12 faces the heat dissipation member 72.

[0261] As shown in Fig. 93, the end surface 13 of the substrate 1 faces the y direction. The end surface 13 is connected to the back surface 12. The intermediate surface 14 is connected to the main surface 11 and the end surface 13. The intermediate surface 14 includes an inclined region 14A inclined with respect to the main surface 11. As shown in Fig. 93, in the thermal printhead D10, the inclined region 14A corresponds to the entire intermediate surface 14. As shown in Figs. 93 and 94, the inclined region 14A is inclined with respect to the main surface 11 at an inclination angle α. The surface roughness of the end surface 13 is greater than the surface roughness of the intermediate surface 14.

[0262] As shown in FIG. 93, the insulating layer 2 covers the main surface 11 and the intermediate surface 14 of the substrate 1. The insulating layer 2 is located between the substrate 1 and the resistor layer 3. The insulating layer 2 electrically insulates the substrate 1 from the resistor layer 3 and the wiring layer 4. The insulating layer 2 is made of silicon dioxide (SiO2) using tetraethyl orthosilicate (TEOS) as a raw material, for example. An example thickness of the insulating layer 2 is 1 μm or more and 15 μm or less. An end surface 13 of the substrate 1 is exposed from the insulating layer 2.

[0263] As shown in FIG. 93, the resistor layer 3 is formed on the main surface 11 and the intermediate surface 14 of the substrate 1. Alternatively, the resistor layer 3 may be formed only on the intermediate surface 14. The resistor layer 3 is in contact with the insulating layer 2. The resistor layer 3 is made of, for example, tantalum nitride (TaN). The resistor layer 3 has a thickness of, for example, 0.02 μm or more and 0.1 μm or less. The end surface 13 of the substrate 1 is exposed from the resistor layer 3. In the example shown in FIG. 93, the entire end surface 13 is not covered by the resistor layer 3. In addition, it is preferable that the tip portion of the resistor layer 3 on the intermediate surface 14 (the portion located on the most downstream side in a certain layer (the resistor layer 3 in this case)) is covered by the protective layer 5. In this case, the resistor layer 3 to which a voltage is applied is not exposed at the tip surface of the thermal printhead D10 (the surface located on the most downstream side in the thermal printhead D10 and including the end surface 13). This configuration ensures safety when using the thermal printhead D10.

[0264] As shown in Figs. 90, 91 and 93, the resistor layer 3 includes a plurality of heat generating portions 31. In the resistor layer 3, the plurality of heat generating portions 31 are exposed from the wiring layer 4. When the plurality of heat generating portions 31 are selectively energized from the wiring layer 4, the plurality of heat generating portions 31 locally heat the recording medium 78. The plurality of heat generating portions 31 are arranged in the x direction. Of the plurality of heat generating portions 31, two adjacent heat generating portions 31 in the x direction are positioned apart from each other. When viewed along the z direction, the plurality of heat generating portions 31 overlap the inclined region 14A (intermediate surface 14) of the substrate 1. As shown in Fig. 92, in the thermal printer 100, the plurality of heat generating portions 31 face the platen roller 79.

[0265] As shown in FIG. 93, the wiring layer 4 is formed in contact with the resistor layer 3. The wiring layer 4 forms a conductive path for passing electricity to the multiple heating parts 31 of the resistor layer 3. The electrical resistivity of the wiring layer 4 is smaller than that of the resistor layer 3. The wiring layer 4 is a metal layer made of, for example, copper (Cu). An example of the thickness of the wiring layer 4 is 0.3 μm or more and 2.0 μm or less. In addition, the wiring layer 4 may be configured to be made of two metal layers, a titanium (Ti) layer laminated on the resistor layer 3 and a copper layer laminated on the titanium layer. In this case, an example of the thickness of the titanium layer is 0.1 μm or more and 0.2 μm or less. The wiring layer 4 is formed on the main surface 11 and the intermediate surface 14 of the substrate 1. The wiring layer 4 is located away from the boundary 15 between the intermediate surface 14 and the end surface 13 of the substrate 1. The end surface 13 is exposed from the wiring layer 4. 93, the end surface 13 is not entirely covered by the wiring layer 4. In addition, the tip of the wiring layer 4 at the intermediate surface 14 is covered by the protective layer 5. This results in a configuration in which the wiring layer 4 to which a voltage is applied is not exposed at the tip surface of the thermal printhead D10. This configuration ensures safety when using the thermal printhead D10.

[0266] In the thermal printhead D10, as shown in FIGS. 90 and 91, the wiring layer 4 includes a common wiring 41, a plurality of individual wirings 42, and a plurality of relay wirings 43. Each of these is electrically connected to one of the plurality of heat generating parts 31. Of these, the common wiring 41 and each of the plurality of individual wirings 42 include a portion formed on the main surface 11 of the substrate 1 and a portion formed on the intermediate surface 14 of the substrate 1. The common wiring 41 and the plurality of individual wirings 42 are located on the side where the main surface 11 is located relative to the plurality of heat generating parts 31 in the y direction (upstream side in the y direction). The plurality of relay wirings 43 are located on the opposite side to the common wiring 41 and the plurality of individual wirings 42 relative to the plurality of heat generating parts 31 in the y direction (downstream side in the y direction). The plurality of relay wirings 43 are formed on the intermediate surface 14.

[0267] As shown in FIG. 90 and FIG. 91, the common wiring 41 has a base 411 and a plurality of extending portions 412. The base 411 is located upstream of the plurality of individual wirings 42 in the y direction. The base 411 is strip-shaped extending in the x direction. The plurality of extending portions 412 are strip-shaped extending from the end of the base 411 on the downstream side in the y direction toward the plurality of heat generating portions 31. The plurality of extending portions 412 are arranged along the x direction. A portion of each of the plurality of extending portions 412 is formed on the intermediate surface 14 of the substrate 1. Each of the plurality of extending portions 412 is conductive to one of the plurality of heat generating portions 31. In the common wiring 41, a current flows from the base 411 to the plurality of heat generating portions 31 via the plurality of extending portions 412.

[0268] As shown in FIG. 90 and FIG. 91, each of the individual wirings 42 has a pad portion 421 and an extension portion 422. The pad portion 421 is located on the upstream side in the y direction in each of the individual wirings 42. The extension portion 422 is a strip extending from the pad portion 421 toward the heat generating portions 31. The extension portions 422 of the individual wirings 42 are arranged along the x direction. A part of the extension portion 422 is formed on the intermediate surface 14 of the substrate 1. The extension portion 422 is electrically connected to one of the heat generating portions 31. In the x direction, the extension portion 422 is adjacent to one of the extension portions 412 of the common wiring 41. In each of the individual wirings 42, a current flows from one of the heat generating portions 31 to the pad portion 421 via the extension portion 422.

[0269] As shown in FIG. 90 and FIG. 91, each of the multiple relay wirings 43 is electrically connected to two adjacent heat generating parts 31 among the multiple heat generating parts 31. One of the two heat generating parts 31 is electrically connected to one of the multiple extending parts 412 of the common wiring 41. The other of the two heat generating parts 31 is electrically connected to one of the extending parts 422 of the multiple individual wirings 42. As a result, each of the multiple relay wirings 43 is electrically connected to the common wiring 41 and one of the multiple individual wirings 42 via the two heat generating parts 31. In each of the multiple relay wirings 43, a current flows from one of the two heat generating parts 31 that is electrically connected to one of the multiple extending parts 412 of the common wiring 41 to the other of the two heat generating parts 31 that is electrically connected to one of the extending parts 422 of the multiple individual wirings 42. The two heat generating portions 31 correspond to one point (dot) formed on the recording medium 78.

[0270] As shown in FIG. 93, the protective layer 5 covers the multiple heat generating parts 31 of the resistor layer 3 and the wiring layer 4. The protective layer 5 has electrical insulation properties. The protective layer 5 contains silicon. The protective layer 5 is made of, for example, silicon dioxide, silicon nitride (Si3N4), or silicon carbide (SiC). Alternatively, the protective layer 5 may be a laminate made of multiple types of these materials. An example of the thickness of the protective layer 5 is 1.0 μm or more and 10 μm or less. In the thermal printer 100, the recording medium 78 is pressed against the area of ​​the protective layer 5 that covers the multiple heat generating parts 31 by the platen roller 79 shown in FIG. 92. The end surface 13 of the substrate 1 is exposed from the protective layer 5.

[0271] 93, a wiring opening 51 is provided in the protective layer 5. The wiring opening 51 penetrates the protective layer 5 in the z-direction. From the wiring opening 51, the pad portions 421 of the individual wirings 42 and a part of each of the extension portions 422 of the individual wirings 42 are exposed.

[0272] The covering layer 6 covers the protective layer 5 as shown in Fig. 93. When viewed along the z direction, the covering layer 6 overlaps the heat generating portion 31 of the resistor layer 3. The covering layer 6 is made of, for example, silicon carbide. The end surface 13 of the substrate 1 is exposed from the covering layer 6.

[0273] As shown in FIG. 92, wiring board 71 is located upstream of substrate 1 in the y direction. As shown in FIG. 89, as viewed along the z direction, the multiple individual wirings 42 are located between wiring board 71 and the multiple heat generating portions 31 of resistor layer 3 in the y direction. As viewed along the z direction, the area of ​​wiring board 71 is larger than the area of ​​substrate 1. Furthermore, as viewed along the z direction, wiring board 71 has a rectangular shape with the x direction as the longitudinal direction. Wiring board 71 is, for example, a PCB substrate. Multiple driving elements 73 and a connector 77 are mounted on wiring board 71.

[0274] As shown in FIG. 92, the heat dissipation member 72 faces the rear surface 12 of the substrate 1. The rear surface 12 is joined to the heat dissipation member 72. The wiring board 71 is fixed to the heat dissipation member 72 by a fastening member such as a screw. When the thermal printhead D10 is in use, a portion of the heat generated from the multiple heat generating portions 31 of the resistor layer 3 is conducted to the heat dissipation member 72 via the substrate 1. The heat conducted to the heat dissipation member 72 is dissipated to the outside. The heat dissipation member 72 is made of, for example, aluminum (Al).

[0275] As shown in FIG. 89 and FIG. 92, the driving elements 73 are mounted on the wiring board 71 via an electrically insulating die bonding material (not shown). Each of the driving elements 73 is a semiconductor element in which various circuits are configured. One end of each of the first wires 74 and one end of each of the second wires 75 are joined to each of the driving elements 73. The other end of each of the first wires 74 is individually joined to the pad parts 421 of the individual wirings 42. The other end of each of the second wires 75 is joined to a wiring (not shown) provided on the wiring board 71 and conductive to the connector 77. As a result, a print signal, a control signal, and a voltage (including a ground potential) for operating each of the driving elements 73 are input from the outside to the driving elements 73 via the connector 77. The driving elements 73 selectively apply a voltage to the individual wirings 42 based on these electric signals. As a result, the heating parts 31 selectively generate heat.

[0276] As shown in Fig. 92, the sealing resin 76 covers the driving elements 73, the first wires 74, and the second wires 75, as well as parts of the substrate 1 and the wiring substrate 71. The sealing resin 76 has electrical insulation properties. The sealing resin 76 is, for example, a black, soft synthetic resin used as an underfill. Alternatively, the sealing resin 76 may be a black, hard synthetic resin.

[0277] As shown in FIGS. 89 and 92, the connector 77 is mounted on one end of the wiring board 71 in the y direction. The connector 77 is connected to a control unit (not shown) of the thermal printer 100. The connector 77 has a plurality of pins. Some of the plurality of pins are electrically connected to wiring (not shown) on the wiring board 71 to which the plurality of second wires 75 are joined. Furthermore, another portion of the plurality of pins is electrically connected to wiring (not shown) on the wiring board 71 that is electrically connected to the base 411 of the common wiring 41. A printing voltage (including ground potential) applied to the plurality of heat generating portions 31 is supplied to still another portion of the plurality of pins.

[0278] Next, an example of a method for manufacturing the thermal printhead D10 will be described with reference to FIGS.

[0279] As shown in FIGS. 95 and 96, a groove 813 is formed in a base material 81.

[0280] Specifically, as shown in FIG. 95, a first mask layer 891 covering the base material 81 and a second mask layer 892 covering a part of the first mask layer 891 are formed. The base material 81 is made of a semiconductor material. The semiconductor material is, for example, a single crystal material of silicon. The base material 81 is a silicon wafer. In a direction perpendicular to the z direction, a plurality of regions corresponding to the plurality of substrates 1 are connected together to form the base material 81. The base material 81 has a main surface 811 and a back surface 812. The main surface 811 and the back surface 812 face in opposite directions to each other in the z direction. The main surface 811 and the back surface 812 of the base material 81 are both planes with Miller indices (100). The first mask layer 891 is formed so as to cover the main surface 811 and the back surface 812. The first mask layer 891 is made of silicon dioxide. The second mask layer 892 is formed so as to cover the region of the first mask layer 891 covering the main surface 811. The second mask layer 892 is made of silicon nitride. A mask opening 893 penetrating in the z direction is formed in the region of the first mask layer 891 covering the main surface 811 and in the second mask layer 892 covering this region.

[0281] In forming the first mask layer 891 and the second mask layer 892, first, a thin film of silicon dioxide is formed by thermal oxidation to cover the main surface 811 and the back surface 812. Next, a thin film of silicon nitride is formed by thermal CVD (Chemical Vapor Deposition) to cover the region of the first mask layer 891 covering the main surface 811. Finally, a part of the region of the thin film of silicon dioxide covering the main surface 811 and a part of the thin film of silicon nitride covering the region are removed by lithography patterning and reactive ion etching (RIE). As a result, the first mask layer 891 and the second mask layer 892 are formed, and mask openings 893 are formed in the region of the first mask layer 891 covering the main surface 811 and in the second mask layer 892 covering the region.

[0282] As the first mask layer 891, a thin film of silicon nitride covering the main surface 811 and the back surface 812 may be formed by thermal CVD. In this case, by lithography patterning and reactive ion etching, a predetermined region on the main surface 811 that is covered by the first mask layer 891 and a mask opening 893 that is a region other than that region where the main surface 811 is exposed are formed.

[0283] Next, as shown in FIG. 96, a groove 813 is formed in the substrate 81. The groove 813 is formed by wet etching the area of ​​the main surface 811 of the substrate 81 exposed by the mask opening 893 shown in FIG. 96 using an aqueous solution of potassium hydroxide (KOH). The etching is anisotropic. Finally, the first mask layer 891 and the second mask layer 892 are removed by wet etching using hydrofluoric acid (HF). In this manner, the groove 813 is formed in the substrate 81. The groove 813 is recessed from the main surface 811 in the z direction and extends along the x direction. The groove 813 is defined by a pair of inclined surfaces 814 and a bottom surface 815. The pair of inclined surfaces 814 are connected to the main surface 811 and face each other in the y direction. The inclination angles α of the pair of inclined surfaces 814 with respect to the main surface 11 are equal to each other. The bottom surface 815 is located between the main surface 811 and the back surface 812 in the z direction, and is connected to the pair of inclined surfaces 814. In this manner, the groove portion 813 is formed by forming the pair of inclined surfaces 814 and the bottom surface 815 in the base material 81 by anisotropic etching.

[0284] After forming the grooves 813 in the base material 81, a thin film of silicon dioxide covering the main surface 11 may be formed by a thermal oxidation method. A metal layer may be laminated by plating on the pads 421 of the individual wirings 42 to which the first wires 74 are individually bonded. The thin film of silicon dioxide has the effect of suppressing abnormal growth of the metal layer when the metal layer is laminated by plating.

[0285] 97, an insulating layer 2 is formed to cover the main surface 11, the pair of inclined surfaces 814, and the bottom surface 815 of the base material 81. The insulating layer 2 is formed by laminating thin films of silicon dioxide formed by plasma CVD using tetraethyl orthosilicate (TEOS) as a raw material gas on the base material 81 multiple times.

[0286] Next, as shown in Fig. 98 to Fig. 100, a resistor layer 3 and a wiring layer 4 are formed. The resistor layer 3 includes a plurality of heat generating portions 31 arranged in the x direction. The wiring layer 4 is electrically connected to the plurality of heat generating portions 31.

[0287] As shown in Fig. 98, a resistor film 82 is formed on a substrate 81. The resistor film 82 is formed so as to cover the entire surface of the insulating layer 2. The resistor film 82 is formed by laminating a thin film of tantalum nitride on the insulating layer 2 by a sputtering method.

[0288] 99, a conductive layer 83 is formed to cover the entire surface of the resistor film 82. The conductive layer 83 is formed by laminating a thin copper film multiple times on the resistor film 82 by a sputtering method. Alternatively, the conductive layer 83 may be formed by laminating a thin titanium film on the resistor film 82 by a sputtering method, and then laminating a thin copper film multiple times on the thin titanium film by a sputtering method.

[0289] Next, as shown in FIG. 100, lithography patterning is performed on the conductive layer 83, and then a portion of the conductive layer 83 is removed. The removal is performed by wet etching using a mixed solution of sulfuric acid (H2SO4) and hydrogen peroxide (H2O2). As a result, the wiring layer 4 is formed in contact with the resistor film 82. In addition, a plurality of heating portions 31 of the resistor layer 3 are formed on a pair of inclined surfaces 814 of the substrate 81.

[0290] Next, as shown in FIG. 101, a protective layer 5 is formed to cover the heat generating parts 31 of the resistor layer 3 and the wiring layer 4. The protective layer 5 is formed by laminating a thin film of silicon nitride on the heat generating parts 31 and the wiring layer 4 by plasma CVD. Furthermore, in this process, a wiring opening 51 shown in FIG. 93 is formed in the protective layer 5. The wiring opening 51 is formed by removing a part of the protective layer 5 after lithographic patterning is performed on the protective layer 5. The removal is performed by reactive ion etching. As a result, a part of the individual wirings 42 (the pad parts 421 of the individual wirings 42 shown in FIG. 93 and a part of each of the extension parts 422 of the individual wirings 42) is exposed from the wiring opening 51. A part of each of the individual wirings 42 and exposed from the wiring opening 51 forms a pad part 421 to which the first wires 74 are individually bonded by wire bonding, for example. A metal layer of gold or the like may be laminated by plating on each portion (including pad portion 421) of the plurality of individual wirings 42 exposed from wiring opening 51.

[0291] Next, as shown in Fig. 102, a coating layer 6 is formed to cover the protective layer 5. The coating layer 6 is formed by laminating a thin film of silicon carbide on the protective layer 5 by plasma CVD. In this step, the coating layer 6 is made to overlap the multiple heating portions 31 of the resistor layer 3 when viewed along the z direction.

[0292] Next, as shown in FIG. 103, the substrate 81 is cut in the z direction. A dicing blade 88 containing abrasive grains is used to cut the substrate 81. In this step, the grooves 813 of the substrate 81 are cut in the y direction. In this step, the substrate 81 cut becomes the substrate 1, and the substrate 1 has a main surface 11, a back surface 12, an end surface 13, and an intermediate surface 14. The main surface 11 corresponds to a part of the main surface 811 of the substrate 81. The back surface 12 corresponds to a part of the back surface 812 of the substrate 81. The end surface 13 corresponds to the cut surface of the substrate 81 in this step. The intermediate surface 14 corresponds to a part of one of a pair of inclined surfaces 814 of the substrate 81. Thus, in this step, a main part of the thermal printhead D10 including the substrate 1 is obtained. The reason why the surface roughness of end face 13 is greater than the surface roughness of intermediate face 14 is that end face 13 is a cut surface of substrate 81 and is a machined surface that includes machining marks caused by abrasive grains, whereas intermediate face 14 is a machined surface in which part of substrate 81 has been removed by anisotropic etching.

[0293] A laser beam may be used in the step of cutting the base material 81 in the z-direction. In this step, a laser beam is used to form cracks, grooves, or a plurality of blind holes arranged in a line at a predetermined interval on the main surface 811 of the base material 81, and then an external force is applied to the base material 81 to cut the base material 81. In this step as well, an end surface 13 having a surface roughness greater than that of the intermediate surface 14 is obtained.

[0294] Next, a plurality of driving elements 73 and a connector 77 are mounted on the wiring board 71. Next, the rear surface 12 of the substrate 1 and the wiring board 71 are bonded to the heat dissipation member 72. Next, a plurality of first wires 74 and a plurality of second wires 75 are bonded to the wiring board 71. Finally, a sealing resin 76 that covers the driving elements 73, the plurality of first wires 74, and the plurality of second wires 75 is formed on the substrate 1 and the wiring board 71. Through the above steps, the thermal printhead D10 is obtained.

[0295] Next, a thermal printhead D11, which is a modification of the thermal printhead D10, will be described with reference to FIG.

[0296] As shown in FIG. 104, in the thermal printhead D11, the configuration of the intermediate surface 14 is different from that of the thermal printhead D10. The intermediate surface 14 of the thermal printhead D11 includes an inclined region 14A and a protruding region 14B. The inclined region 14A is connected to the main surface 11. The protruding region 14B is connected to the end surface 13 and the inclined region 14A. The protruding region 14B faces the same side as the main surface 11 in the z direction. The protruding region 14B and the inclined region 14A are covered by the insulating layer 2. In the thermal printhead D11, too, the surface roughness of the end surface 13 is greater than the surface roughness of the intermediate surface 14. The intermediate surface 14 of the thermal printhead D11 is obtained by cutting the base material 81 so that a part of the bottom surface 815 remains in the step of cutting the base material 81 in the z direction (see FIG. 103) in the manufacturing process of the thermal printhead D10.

[0297] Next, a modified method of manufacturing the thermal printhead D10 will be described with reference to FIG.

[0298] As a modification of the process of forming grooves 813 in substrate 81 (see FIGS. 96 and 97) in the manufacturing process of thermal printhead D10, there is a method of forming grooves 813 in substrate 81 as shown in FIG. 105. Groove 813 is formed by forming only a pair of inclined surfaces 814 in substrate 81 by anisotropic etching. The lower ends of the pair of inclined surfaces 814 are connected to each other. Groove 813 is defined by only the pair of inclined surfaces 814.

[0299] Next, the function and effect of the thermal printhead D10 will be described.

[0300] The thermal printhead D10 has an end surface 13 facing the y direction, and an intermediate surface 14 including an inclined region 14A inclined with respect to the main surface 11 and connected to the main surface 11 and the end surface 13. When viewed along the z direction, the heat generating portions 31 of the resistor layer 3 overlap the inclined region 14A. This allows the recording medium 78 to come into contact with a small area on the inclined region 14A when the thermal printhead D10 is in use. This allows the heat generated by the heat generating portions 31 to be efficiently conducted to the recording medium 78. Therefore, according to the thermal printhead D10, firstly, the amount of heat generated from the heat generating portions 31 required for printing on the recording medium 78 is relatively small, so that power consumption can be reduced. Secondly, print quality can be improved.

[0301] In the thermal printhead D10, the end face 13 of the substrate 1 is exposed from both the resistor layer 3 and the wiring layer 4. Such a configuration of the end face 13 can be obtained by providing, in the manufacture of the thermal printhead D10, a step of forming a groove portion 813 in the base material 81 shown in Figs. 95 and 96 and a step of cutting the base material 81 in the z direction shown in Fig. 103.

[0302] 95 and 96, in the step of forming grooves 813 in substrate 81, a pair of inclined surfaces 814 that define at least a portion of grooves 813 are formed in substrate 81. In the subsequent step of forming resistor layer 3 (see FIGS. 98 to 100), resistor layer 3 is formed on the pair of inclined surfaces 814. This allows thermal printhead D10 to be provided with substrate 1 having intermediate surface 14 that includes inclined region 14A, and to have a configuration in which multiple heat generating portions 31 overlap inclined region 14A when viewed along the z direction.

[0303] When forming a pair of inclined surfaces 814 on the substrate 81 to improve the printing quality, the time required to form the pair of inclined surfaces 814 is shorter when forming a groove 813 recessed in the z direction from the main surface 811 of the substrate 81 than when forming a convex portion protruding in the z direction from the main surface 811 of the substrate 81. This is because the volume of the substrate 81 removed in forming the pair of inclined surfaces 814 is smaller when forming the groove 813 than when forming the convex portion. Furthermore, when cutting the substrate 81 in the z direction, the groove 813 is divided in the y direction, so that the number of main parts of the thermal printhead D10 manufactured is doubled. Therefore, the manufacturing method of the thermal printhead D10 can improve the manufacturing efficiency, and the end surface 13 of the substrate 1 can be said to be a trace during the manufacturing of the thermal printhead D10 with improved manufacturing efficiency. As described above, the thermal printhead D10 can achieve both improved printing quality and improved manufacturing efficiency of the thermal printhead.

[0304] The base material 81 is made of a semiconductor material (single crystal silicon material). This allows the pair of inclined surfaces 814 to be formed on the base material 81 by anisotropic etching.

[0305] The substrate 1 is made of a semiconductor material (single crystal silicon material). This gives the substrate 1 a relatively high thermal conductivity (approximately 170 W / (m·K)), which improves the heat dissipation of the thermal printhead D10. Furthermore, the end face 13 of the substrate 1 being exposed to the outside contributes to improved heat dissipation. In this case, the surface roughness of the end face 13 being greater than the surface roughness of the intermediate face 14 of the substrate 1 leads to an increase in the surface area of ​​the end face 13, making the improvement in the heat dissipation of the thermal printhead D10 more effective. In addition, the improved heat dissipation of the thermal printhead D10 contributes to faster printing speeds.

[0306] The wiring layer 4 includes a portion formed on the intermediate surface 14, and is located away from the boundary 15 between the intermediate surface 14 and the end surface 13. As a result, in the step of cutting the base material 81 in the z-direction shown in Fig. 105, the base material 81 is cut without the dicing blade 88 coming into contact with the wiring layer 4. Therefore, it is possible to prevent the wiring layer 4 from being broken in this step.

[0307] Thermal printhead D10 further includes a protective layer 5 that covers the multiple heat generating portions 31 and the wiring layer 4. As a result, the multiple heat generating portions 31 and the wiring layer 4 are protected by the protective layer 5, and the recording medium 78 comes into contact with the thermal printhead D10 more smoothly when the thermal printhead D10 is in use.

[0308] The thermal printhead D10 includes a covering layer 6 that covers the protective layer 5. When viewed along the z direction, the covering layer 6 overlaps a plurality of heat generating parts 31. This results in a configuration in which the recording medium 78 comes into contact with the covering layer 6 when the thermal printhead D10 is in use. This makes it possible to suppress wear of the protective layer 5 caused by the feeding of the recording medium 78.

[0309] The thermal printhead D10 further includes a heat dissipation member 72. The rear surface 12 of the substrate 1 is joined to the heat dissipation member 72. This allows a portion of the heat generated from the multiple heat generating parts 31 to be rapidly dissipated to the outside via the substrate 1 and the heat dissipation member 72 when the thermal printhead D10 is in use.

[0310] A thermal printhead D20 according to a second embodiment of the fourth aspect of the present disclosure will be described with reference to Figs. 106 to 108. In these figures, elements that are the same as or similar to those of the thermal printhead D10 described above are given the same reference numerals, and duplicated explanations will be omitted. In Fig. 106, for ease of understanding, the protective layer 5 and the covering layer 6 are shown through, and the multiple first wires 74, the multiple second wires 75, and the sealing resin 76 are not shown. In Figs. 107 and 108, for ease of understanding, the protective layer 5 and the covering layer 6 are shown through.

[0311] In thermal printhead D20, the configuration of the wiring layer 4 differs from that of the thermal printhead D10 described above.

[0312] As shown in FIGS. 106 to 108, in a thermal printhead D20, the wiring layer 4 includes a common wiring 41 and a plurality of individual wirings 42, but does not include a plurality of relay wirings 43. The common wiring 41 is located on the side where the end face 13 of the substrate 1 is located relative to the plurality of heat generating portions 31 of the resistor layer 3 in the y direction (the downstream side in the y direction). The plurality of individual wirings 42 are located on the opposite side of the common wiring 41 relative to the plurality of heat generating portions 31 in the y direction. The common wiring 41 and a portion of each of the extension portions 422 of the plurality of individual wirings 42 are formed on the intermediate surface 14 of the substrate 1.

[0313] 107 and 108, the base 411 of the common wiring 41 is located farthest downstream in the y direction from the heat generating portions 31. The extension portions 412 of the common wiring 41 are strip-shaped and extend from the upstream end of the base 411 in the y direction toward the heat generating portions 31. The heat generating portions 31 are located between the common wiring 41 and the individual wirings 42 in the y direction. When viewed along the z direction, each of the heat generating portions 31 is sandwiched in the y direction between one of the extension portions 412 of the common wiring 41 and one of the extension portions 422 of the individual wirings 42.

[0314] Next, the function and effect of the thermal printhead D20 will be described.

[0315] The thermal printhead D20 has an end surface 13 facing the y direction, and an intermediate surface 14 including an inclined region 14A inclined with respect to the main surface 11 and connected to the main surface 11 and the end surface 13. When viewed along the z direction, the multiple heat generating portions 31 of the resistor layer 3 overlap the inclined region 14A. The end surface 13 is exposed from both the resistor layer 3 and the wiring layer 4. Therefore, the thermal printhead D20 can also achieve both improved print quality and improved manufacturing efficiency of the thermal printhead. Furthermore, by having a configuration similar to that of the thermal printhead D10, it achieves the effects corresponding to that configuration.

[0316] In the thermal printhead D20, the heat generating portions 31 are located between the common wiring 41 and the individual wirings 42 in the y direction. In other words, one heat generating portion 31 corresponds to one point (dot) formed on the recording medium 78. This allows the number of the individual wirings 42 per unit length along the x direction to be increased compared to the configuration of the wiring layer 4 of the thermal printhead D10 (see FIG. 91). This allows the number of heat generating portions 31 corresponding to one dot per unit length along the x direction to be increased. This increases the number of print dots (dot density) per unit length along the x direction when printing on the recording medium 78, making it possible to perform more detailed printing on the recording medium 78.

[0317] The configuration of the wiring layer 4 included in each of the thermal printhead D10 and the thermal printhead D20 is an example. The configuration of the wiring layer 4 in the present disclosure is not limited to the configuration included in each of the thermal printhead D10 and the thermal printhead D20.

[0318] The present disclosure is not limited to the embodiment according to the fourth aspect described above. The specific configuration of each part of the present disclosure can be freely changed in various ways. The embodiment according to the fourth aspect of the present disclosure includes the configurations described in the following Supplementary Notes 1D to 16D.

[0319] Appendix 1D. a substrate having a main surface facing a thickness direction, an end surface facing a sub-scanning direction, and an intermediate surface including an inclined region inclined with respect to the main surface and connected to the main surface and the end surface; a resistor layer including a plurality of heat generating portions arranged in a main scanning direction and formed on the intermediate surface; a wiring layer that is electrically connected to the plurality of heat generating portions and is formed in contact with the resistor layer, When viewed along the thickness direction, the heat generating portions overlap the inclined region, The end surface of the thermal printhead is exposed from the resistor layer and the wiring layer. Appendix 2D. The thermal printhead of claim 1D, wherein the end surface has a surface roughness greater than a surface roughness of the intermediate surface. Appendix 3D. The thermal printhead of claim 1D or 2D, wherein the wiring layer includes a portion formed on the intermediate surface and located away from the boundary between the intermediate surface and the end surface. Appendix 4D. the wiring layer includes common wiring and individual wiring, each of the common wiring and the individual wiring is electrically connected to one of the plurality of heat generating portions; The thermal printhead of claim 3D, wherein each of the common wiring and the individual wiring includes a portion formed on the intermediate surface. Appendix 5D. the common wiring and the individual wiring are located on a side of the main surface with respect to the plurality of heat generating portions in the sub-scanning direction, and are adjacent to each other in the main scanning direction; the wiring layer includes relay wiring located on an opposite side of the common wiring and the individual wiring with respect to the plurality of heat generating portions in the sub-scanning direction, The thermal printhead of claim 4D, wherein the relay wiring is electrically connected to the common wiring and the individual wiring via two adjacent heat generating portions among the plurality of heat generating portions. Appendix 6D. the common wiring is located on a side where the end surface is located with respect to the plurality of heat generating portions in the sub-scanning direction, the individual wiring is located on an opposite side of the common wiring with respect to the plurality of heat generating portions in the sub-scanning direction, The thermal printhead according to claim 4D, wherein the plurality of heat generating portions are positioned between the common wiring and the individual wiring in the sub-scanning direction. Appendix 7D. the substrate is made of a semiconductor material; The thermal printhead of any preceding claim, wherein the semiconductor material comprises a single crystal material of silicon. Appendix 8D. further comprising an insulating layer covering the main surface and the intermediate surface; the insulating layer is located between the substrate and the resistor layer; The thermal printhead of claim 7D, wherein the end surface is exposed from the insulating layer. Appendix 9D. a protective layer covering the plurality of heat generating portions and the wiring layer; 8D. The thermal printhead of claim 1, wherein the end surface is exposed from the protective layer. Appendix 10D. Further comprising a coating layer covering the protective layer, When viewed along the thickness direction, the coating layer overlaps the plurality of heat generating portions, The thermal printhead of claim 9D, wherein the end surface is exposed from the covering layer. Appendix 11D. Further comprising a heat dissipation member, the substrate has a back surface facing the opposite side to the main surface in the thickness direction, The thermal printhead according to any one of appendixes 1D to 10D, wherein the rear surface is joined to the heat dissipation member. Appendix 12D. A step of forming a groove portion in a substrate having a main surface facing a thickness direction, the groove portion being recessed from the main surface in the thickness direction and extending along a main scanning direction; forming a resistor layer on the base material, the resistor layer including a plurality of heat generating portions arranged in the main scanning direction; forming a wiring layer that is electrically connected to the plurality of heat generating portions in contact with the resistor layer; In the step of forming the groove portion, a pair of inclined surfaces are formed on the base material, the inclined surfaces are connected to the main surface, face each other in the sub-scanning direction, and define at least a portion of the groove portion; In the step of forming the resistor layer, the resistor layer is formed on the pair of inclined surfaces, The method for manufacturing a thermal printhead further comprises, after the step of forming the wiring layer, a step of cutting the base material in the thickness direction so that the groove portion is divided in the sub-scanning direction. Appendix 13D. the substrate is made of a semiconductor material; the semiconductor material comprises a single crystal material of silicon; The method for manufacturing a thermal printhead according to claim 12D, wherein in the step of forming the groove portion, the pair of inclined surfaces are formed by anisotropic etching. Appendix 14D. The method for manufacturing a thermal printhead described in Appendix 13D, further comprising a step of forming an insulating layer covering the main surface and the pair of inclined surfaces after the step of forming the groove portion and before the step of forming the resistor layer. Appendix 15D. A method for manufacturing a thermal printhead described in any one of Appendices 12D to 14D, further comprising a step of forming a protective layer covering the multiple heat generating portions and the wiring layer after the step of forming the wiring layer and before the step of cutting the substrate. Appendix 16D. The method further includes a step of forming a covering layer that covers the protective layer after the step of forming the protective layer and before the step of cutting the base material, The method for manufacturing a thermal printhead described in Appendix 15D, wherein in the step of forming the covering layer, the covering layer overlaps the plurality of heat generating portions when viewed along the thickness direction.

[0320] [Explanation of symbols according to the fourth aspect] D10, D20: Thermal print head 1: Substrate 11: Main surface 12: Back surface 13: End surface 14: Intermediate surface 14A: Slope area 14B: Overhang area 15: Boundary 2: Insulation layer 3: Resistor layer 31: Heat generating portion 4: Wiring layer 41: Common wiring 411: Base 412: Extension 42: Individual wiring 421: Pad section 422: Extension section 43: Relay wiring 5: Protective layer 51: Wiring opening 6: Covering layer 71: Wiring board 72: Heat dissipation member 73: Driving element 74: First wire 75: Second wire 76: Sealing resin 77: Connector 78: Recording medium 79: Platen roller 81: Substrate 811: Main surface 812: Back surface 813: Groove 814: Inclined surface 815: Bottom surface 82: Resistor film 83: Conductive layer 88: Dicing blade 891: First mask layer 892: Second mask layer 893: Mask opening α: Tilt angle

Claims

1. a semiconductor substrate having a main surface and a back surface spaced apart from each other in a thickness direction, and a first penetrating portion formed therein that penetrates from the main surface to the back surface; a resistor layer including a plurality of heat generating portions arranged in a main scanning direction and formed on the main surface; A first electrode formed on the back surface; a wiring layer formed on the resistor layer and electrically connected to the heat generating portions; a first through wiring housed in the first through portion; a plurality of second electrodes and a plurality of second through-wires formed on the rear surface; a first insulating layer covering the main surface; the wiring layer includes a common wiring located on a first side in a sub-scanning direction with respect to the plurality of heat generating portions, the first through wiring is connected to the common wiring and the first electrode, the wiring layer includes a plurality of individual wirings located on a second side in the sub-scanning direction with respect to the plurality of heat generating portions, the semiconductor substrate is formed with a plurality of second through portions that penetrate from the main surface to the back surface and are located on an opposite side of the first through portions with respect to the plurality of heat generating portions in the sub-scanning direction, the second through wirings are individually accommodated in the second through portions, each of the plurality of second through wirings is connected to one of the plurality of individual wirings and one of the plurality of second electrodes; the semiconductor substrate has a first inner circumferential surface connected to the main surface and the back surface and defining the first penetrating portion, and a plurality of second inner circumferential surfaces connected to the main surface and the back surface and defining each of the plurality of second penetrating portions; The first insulating layer is in contact with the resistor layer and covers the first inner circumferential surface and the plurality of second inner circumferential surfaces.

2. The main surface includes a base surface and a convex surface that bulges from the base surface in the thickness direction, the convex surface extends along the main scanning direction, The thermal printhead according to claim 1 , wherein the plurality of heat generating portions are formed on the convex surface.

3. The convex surface includes a top surface parallel to the base surface, and a pair of inclined surfaces connected to the top surface and the base surface and positioned apart from each other in the sub-scanning direction, The thermal printhead of claim 2 , wherein the plurality of heat generating portions are formed on the top surface.

4. A thermal printhead as described in Claim 3, wherein a portion of the common wiring and a portion of each of the plurality of individual wirings are formed on one of the pair of inclined surfaces.

5. A thermal printhead as described in claim 4, wherein the pair of inclined surfaces are inclined relative to the base surface so as to approach each other from the base surface to the top surface.

6. Each of the pair of inclined surfaces includes a first region connected to the base surface and a second region connected to the top surface and the first region, 6. The thermal printhead of claim 5, wherein an inclination angle of the second region relative to the base surface is smaller than an inclination angle of the first region relative to the base surface.

7. A thermal printhead as described in any of claims 2 to 6, wherein the semiconductor substrate comprises a single crystal silicon material.

8. Further comprising a second insulating layer covering the back surface and connected to the first insulating layer; 8. The thermal printhead according to claim 1, wherein the first electrode and the plurality of second electrodes are in contact with the second insulating layer.

9. The substrate further includes a heat dissipation layer located between the first electrode and the plurality of second electrodes in the sub-scanning direction and formed in contact with the second insulating layer, The thermal printhead according to claim 8 , wherein the heat dissipation layer overlaps the plurality of heat generating portions when viewed in the thickness direction.

10. The semiconductor device further includes a wiring substrate facing the back surface and having the first electrode and a plurality of second electrodes bonded thereto; The thermal printhead according to claim 9 , wherein the wiring board has a heat sink to which the heat dissipation layer is joined.

11. A thermal printhead as described in any one of claims 1 to 10, further comprising a protective layer covering a portion of the main surface, the multiple heating portions, and the wiring layer.

12. A step of forming a first recess in a substrate made of a semiconductor material, the first recess being recessed in the thickness direction from the main surface, the first recess having a main surface facing a thickness direction; forming a resistor layer including a plurality of heat generating portions arranged in a main scanning direction on the main surface and in the first recess; forming a wiring layer on the resistor layer, the wiring layer being electrically connected to the plurality of heat generating portions; removing a portion of the base material located on an opposite side to the main surface in the thickness direction; forming an electrode on the base material, the electrode being located on an opposite side of the base material from the wiring layer in the thickness direction and being electrically connected to the wiring layer; the step of forming the wiring layer includes a step of forming a common wiring located on a first side in a sub-scanning direction with respect to the plurality of heat generating portions, and a first through wiring accommodated in the first recess and connected to the common wiring; In the step of removing a portion of the base material, the portion of the base material is removed until a portion of the first through wiring is exposed from the base material; the step of forming the electrode includes a step of forming a first electrode that is electrically connected to the common wiring; In the step of forming the first electrode, the first electrode is formed so as to be in contact with the first through wiring.

13. The method further comprises, between the step of forming the first recess and the step of forming the resistor layer, a step of forming a plurality of second recesses which are recessed in the thickness direction from the main surface of the substrate and which are located on the opposite side of the first recesses with respect to the plurality of heating portions in the sub-scanning direction, In the step of forming the resistor layer, a part of the resistor layer is formed in the plurality of second recesses, the step of forming the wiring layer includes a step of forming a plurality of individual wirings located on a second side in the sub-scanning direction with respect to the plurality of heat generating portions, and a plurality of second through wirings individually accommodated in the plurality of second recesses and individually connected to the plurality of individual wirings, In the step of removing a portion of the base material, the portion of the base material is removed until a portion of the plurality of second through wirings is exposed from the base material; The step of forming the electrodes includes a step of forming a plurality of second electrodes that are individually conductive to the plurality of individual wirings, The method for manufacturing a thermal printhead according to claim 12 , wherein in the step of forming the plurality of second electrodes, the plurality of second electrodes are formed so as to be in contact with the plurality of second through-hole wirings individually.

14. The main surface includes a base surface and a convex surface that bulges from the base surface in the thickness direction, The method further includes, before the step of forming the first recess, a step of forming a convex portion on the base material, the convex portion bulging from the base surface in the thickness direction and extending along the main scanning direction and including the convex surface; The method for manufacturing a thermal printhead according to claim 13 , wherein in the step of forming the resistor layer, the plurality of heat generating portions are formed on the convex surface.

15. A method for manufacturing a thermal printhead as described in claim 14, wherein the semiconductor material comprises a single crystal material of silicon.

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