Thermal printhead

Abstract

A thermal printhead according to the present invention comprises a heat-generating substrate, a plurality of heat-generating parts, and a heat-dissipating member. The heat-generating substrate has a heat-generating substrate principal surface and a heat-generating substrate back surface that face opposite sides in the thickness direction. The plurality of heat-generating parts are arranged on the heat-generating substrate principal surface side along a principal scanning direction. The heat-generating substrate is mounted on the heat-dissipating member. The heat-generating substrate back surface has a first area and second areas. The first area is in the center in the principal scanning direction and is adhered to the heat-dissipating member via an adhesive member. The second areas are at respective ends in the principal scanning direction and do not overlap the adhesive member as seen in the thickness direction.

Description

thermal printhead

[0001] The present disclosure relates to thermal printheads.

[0002] Patent Document 1 discloses an example of a conventional thermal printhead. The thermal printhead disclosed therein includes a heat-generating substrate with a heat-generating portion formed thereon, a first substrate with a driver IC mounted thereon, and a heat dissipation member. The heat-generating substrate is made of, for example, silicon, and the first substrate is, for example, a PCB substrate. During the thermal printhead assembly process, the heat-generating substrate and the first substrate are integrated by forming a protective resin across both substrates, and then attached to the heat dissipation member 8. When the protective resin is formed, heat is applied to solidify the protective resin material. At this time, the first substrate, which has a higher linear expansion coefficient than the heat-generating substrate, expands while the heat-generating substrate and the first substrate are fixed together by the protective resin. Subsequently, upon cooling, the first substrate contracts more than the heat-generating substrate, which can cause the heat-generating substrate to bend in the sub-scanning direction. Because the curvature of the heat-generating substrate affects printing characteristics, heat-generating substrates that are bent beyond the specified limit are deemed defective.

[0003] WO2020 / 241581 publication

[0004] An object of the present disclosure is to provide a thermal printhead that is improved over conventional ones, and in particular, in view of the above-mentioned circumstances, an object of the present disclosure is to provide a thermal printhead that can suppress curvature of the heating substrate.

[0005] A thermal printhead provided by a first aspect of the present disclosure includes a heat generating substrate having a main surface and a rear surface facing opposite each other in a thickness direction, a plurality of heat generating portions disposed on the main surface of the heat generating substrate and arranged in a main scanning direction, and a heat dissipation member on which the heat generating substrate is mounted, The rear surface of the heat generating substrate has a first region located in the center in the main scanning direction and adhered to the heat dissipation member via an adhesive member, and second regions located at both ends in the main scanning direction and not overlapping with the adhesive member when viewed in the thickness direction.

[0006] According to the above configuration, it is possible to suppress the bending of the heat generating substrate in the thermal printhead.

[0007] Other features and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.

[0008] FIG. 1 is a plan view showing a thermal printhead according to a first embodiment of the present disclosure. FIG. 2 is a plan view of a main portion of the thermal printhead shown in FIG. 1. FIG. 3 is an enlarged plan view of a main portion of the thermal printhead shown in FIG. 1. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 1. FIG. 5 is a cross-sectional view of a main portion of the thermal printhead shown in FIG. 1. FIG. 6 is a bottom view showing a heat-generating substrate and a first substrate of the thermal printhead shown in FIG. 1. FIG. 7 is a plan view showing a heat dissipation member of the thermal printhead shown in FIG. 1. FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. 7. FIG. 9 is a cross-sectional view of a main portion showing an example of a method for manufacturing the thermal printhead shown in FIG. 1. FIG. 10 is a cross-sectional view of a main portion showing an example of a method for manufacturing the thermal printhead shown in FIG. 1. FIG. 11 is a cross-sectional view of a main portion showing an example of a method for manufacturing the thermal printhead shown in FIG. 1. FIG. 12 is a cross-sectional view of a main portion showing an example of a method for manufacturing the thermal printhead shown in FIG. 1. FIG. 13 is a plan view showing a heat dissipation member 8 of a thermal printhead according to a second embodiment of the present disclosure. Fig. 14 is a cross-sectional view taken along line XIV-XIV in Fig. 13. Fig. 15 is a plan view showing a heat dissipation member 8 of a thermal printhead according to a third embodiment of the present disclosure.

[0009] Preferred embodiments of the present disclosure will now be described in detail with reference to the drawings.

[0010] 1 to 8 show a thermal printhead according to a first embodiment of the present disclosure. The thermal printhead A1 of this embodiment includes a heat-generating substrate 1, a protective layer 2, a conductive layer 3, a resistor layer 4, an insulating layer 18, a first substrate 5, a driver IC 55, a second substrate 6, a connector 69, a third substrate 7, and a heat dissipation member 8. The thermal printhead A1 is incorporated into a printer that prints on a print medium (not shown) that is conveyed between the thermal printhead A1 and a platen roller 91. Examples of such print media include thermal paper for creating barcode sheets and date code sheets.

[0011] FIG. 1 is a plan view of the thermal printhead A1. FIG. 2 is a plan view of the thermal printhead A1's essential parts. FIG. 3 is an enlarged plan view of the thermal printhead A1's essential parts. For ease of understanding, the protective layer 2 is omitted from FIGS. 1 to 3. For ease of understanding, the protective resin 57 and wires 561, which will be described later, are omitted from FIG. 2. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 1. FIG. 5 is a cross-sectional view of the essential parts of the thermal printhead A1. FIG. 6 is a bottom view showing the heat-generating substrate 1 and first substrate 5 of the thermal printhead A1. In FIG. 6, the heat-dissipating member 8 on which the heat-generating substrate 1 and first substrate 5 are mounted is indicated by imaginary lines (two-dot chain lines). FIG. 7 is a plan view showing the heat-dissipating member 8 of the thermal printhead A1. FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. 7. 7 and 8, the heat-generating substrate 1 and first substrate 5 mounted on the heat dissipation member 8 are shown with imaginary lines (two-dot chain lines). In these figures, the longitudinal direction (main scanning direction) of the heat-generating substrate 1 is defined as the x-direction, the lateral direction (sub-scanning direction) as the y-direction, and the thickness direction as the z-direction. In addition, with respect to the y-direction, the lower side in Figures 1 to 3 (the right side in Figures 4 and 5) is defined as the upstream side from which the print medium is fed, and the upper side in Figures 1 to 3 (the left side in Figures 4 and 5) is defined as the downstream side from which the print medium is discharged. This also applies to the following figures.

[0012] The heating substrate 1 is mounted on the heat dissipation member 8 and supports the conductive layer 3 and the resistor layer 4. The heating substrate 1 has an elongated rectangular shape with the x direction as the longitudinal direction and the y direction as the width direction. There are no particular restrictions on the size of the heating substrate 1, but as an example, the thickness of the heating substrate 1 is, for example, about 0.5 to 1 mm. The x direction dimension of the heating substrate 1 is, for example, about 50 to 150 mm, and the y direction dimension is, for example, about 1 to 5 mm.

[0013] In this embodiment, the heating substrate 1 is made of a single-crystal semiconductor, for example, Si. As shown in Figures 4 and 5, the heating substrate 1 has a heating substrate main surface 11 and a heating substrate rear surface 12. The heating substrate main surface 11 and the heating substrate rear surface 12 face opposite each other in the z direction and are parallel to each other. The heating substrate main surface 11 is the surface facing upward in Figures 4 and 5. The heating substrate rear surface 12 is the surface facing downward in Figures 4 and 5.

[0014] As shown in FIG. 6 , the heating substrate rear surface 12 has a first region 12a and a second region 12b. The first region 12a is a region that is adhered to the heat dissipation member 8 (the first support surface 81 described later) via an adhesive member 85 described later. The first region 12a has a rectangular shape that is elongated in the x direction, is located at the center in the x direction, and is located downstream in the y direction. The first region 12a is disposed so as to enclose a plurality of heat generating portions 41 described later when viewed in the z direction. The second region 12b is a region that is adhered to the heat dissipation member 8 (the first support surface 81) via an adhesive member 86 described later. The second region 12b is divided into two rectangular portions, each located at both ends in the x direction, sandwiching the first region 12a. Each second region 12b is located over the entire y direction. Each second region 12b does not overlap the first region 12a or the adhesive member 85 when viewed in the z direction.

[0015] As shown in FIG. 5 , the heating substrate 1 has protrusions 13. The protrusions 13 protrude from the heating substrate main surface 11 in the z direction and extend in the x direction. The protrusions 13 are located downstream in the y direction. The heating substrate 1 is formed by forming a mask layer on the (100) plane (Miller index) of a single-crystal semiconductor material, such as a Si wafer, and then performing anisotropic etching. The peaks remaining due to the mask layer and the etched sloped portions form the protrusions 13. In this embodiment, two anisotropic etchings are performed, resulting in each sloped portion having two inclined surfaces with different slopes. The angles between each sloped surface and the peak are predetermined angles depending on the anisotropic etching. The portions parallel to the heating substrate rear surface 12, revealed by the anisotropic etching, form the heating substrate main surface 11. Therefore, the peaks of the protrusions 13 and the heating substrate main surface 11 are (100) planes.

[0016] As shown in FIG. 5 , the insulating layer 18 covers the heating substrate main surface 11 and the protrusions 13, and serves to more reliably insulate the heating substrate 1 from the resistor layer 4 and the conductive layer 3. The insulating layer 18 may be formed in the region of the heating substrate 1 where the resistor layer 4 or the conductive layer 3 is to be formed. The insulating layer 18 is made of an insulating material, such as SiO2, SiN, or TEOS (tetraethyl orthosilicate). In this embodiment, the insulating layer 18 is made of TEOS. The constituent material of the insulating layer 18 is not limited. The thickness of the insulating layer 18 is not particularly limited, and is, for example, 5 μm to 15 μm, and preferably 5 μm to 10 μm.

[0017] The resistor layer 4 is supported on the heating substrate 1 via an insulating layer 18. The resistor layer 4 is disposed on the heating substrate 1 on the side of the heating substrate main surface 11 in the z direction, covering at least a portion of the heating substrate main surface 11 and the protrusions 13. The resistor layer 4 has a plurality of heating portions 41. The plurality of heating portions 41 are selectively energized to locally heat the print medium. In this embodiment, the heating portions 41 are regions of the resistor layer 4 exposed from the conductive layer 3 and disposed on the inclined portions of the protrusions 13 (more specifically, the inclined surfaces connected to the peaks and downstream in the y direction). The heating portions 41 may be disposed on the peaks or other inclined portions of the protrusions 13, or may be disposed at predetermined positions on the heating substrate main surface 11 without providing the protrusions 13 on the heating substrate 1. The heating portions 41 are arranged along the x direction and spaced apart from one another in the x direction. The shape of the heat generating portion 41 is not particularly limited, and in this embodiment, it is an elongated rectangle with the longitudinal direction in the y direction when viewed in the z direction. The resistor layer 4 is made of, for example, TaN. The constituent material of the resistor layer 4 is not limited. The thickness of the resistor layer 4 is not particularly limited, and is, for example, 0.02 μm to 0.1 μm, and preferably about 0.08 μm. In this embodiment, as shown in FIG. 6 , the multiple heat generating portions 41 overlap the first region 12a when viewed in the z direction and are contained within the first region 12a.

[0018] The conductive layer 3 constitutes a current path for supplying electricity to the plurality of heat generating portions 41. The conductive layer 3 is supported by the heat generating substrate 1, and in this embodiment, as shown in FIG. 5, is laminated on the resistor layer 4. The conductive layer 3 exposes the portions of the resistor layer 4 that will become the heat generating portions 41. The conductive layer 3 is made of a metal material with a lower resistance than the resistor layer 4, such as Cu. The thickness of the conductive layer 3 is not particularly limited, and is, for example, 0.3 μm to 2.0 μm.

[0019] As shown in FIGS. 1 to 3 and 5, in this embodiment, the conductive layer 3 has a plurality of individual electrodes 31, a common electrode 32, and a plurality of relay electrodes 33.

[0020] As shown in Fig. 3, the multiple individual electrodes 31 are each strip-shaped and extend generally in the y direction, and are arranged on the heating substrate main surface 11 and the protrusions 13. The multiple individual electrodes 31 are arranged upstream in the y direction from the multiple heat generating portions 41. Each of the multiple individual electrodes 31 is connected to a different heat generating portion 41. As shown in Figs. 2 and 5, the individual electrodes 31 have individual pads 311. The individual pads 311 are connected to wires 561 for electrical connection with the driver IC 55.

[0021] 2 and 3, the common electrode 32 is disposed on the heating substrate main surface 11 and the protrusions 13, and has a connecting portion 323 and a plurality of strip-shaped portions 324. The strip-shaped portions 324 extend in the y direction. As shown in FIG. 3, one end (the downstream end in the y direction) of each of the strip-shaped portions 324 branches into two, and each branched portion is connected to two adjacent heating portions 41. As shown in FIG. 2, the connecting portion 323 is located on the other end side (the upstream side in the y direction) of the strip-shaped portions 324, extends in the x direction, and connects the strip-shaped portions 324 together.

[0022] 2, 3, and 5, the relay electrodes 33 are arranged on the heating substrate main surface 11 and on the protrusions 13, and are U-shaped with their openings facing upstream in the y direction. A plurality of relay electrodes 33 are arranged at equal intervals in the x direction, downstream of the heating portions 41 in the y direction. Each relay electrode 33 is connected to two adjacent heating portions 41.

[0023] 3, the strip portion 324 of the common electrode 32 is disposed between two individual electrodes 31. One of the two heat generating portions 41 connected to one relay electrode 33 is connected to the common electrode 32, and the other is connected to one of the individual electrodes 31. Therefore, when an individual electrode 31 is energized, a current flows through the heat generating portion 41 connected to it and the heat generating portion 41 connected to that heat generating portion 41 via the relay electrode 33, causing heat generation. In other words, the two heat generating portions 41 generate heat simultaneously.

[0024] There are no limitations on the arrangement and shape of the conductive layer 3. For example, the relay electrode 33 may not be provided, the common electrode 32 may be arranged downstream of the heat generating portion 41 in the y direction, and each heat generating portion 41 may be connected to a different strip portion 324 of the common electrode 32 and an individual electrode 31.

[0025] The protective layer 2 is formed so as to overlap the main surface 11 and the protrusions 13 of the heating substrate 1, and covers the conductive layer 3 and the resistor layer 4. The protective layer 2 is made of an insulating material and protects the conductive layer 3 and the resistor layer 4. The protective layer 2 is made of a material such as SiO2, SiN, SiC, or AlN, and may be composed of a single layer or multiple layers of these. There are no particular limitations on the thickness of the protective layer 2, and it is, for example, about 1.0 μm to 10 μm.

[0026] 5 , in this embodiment, the protective layer 2 has pad openings 21. The pad openings 21 penetrate the protective layer 2 in the z direction. The pad openings 21 expose the individual pads 311 of the individual electrodes 31.

[0027] As shown in FIGS. 1 , 4 , and 6 , the first substrate 5 is mounted on the heat dissipation member 8 and is disposed upstream in the y direction relative to the heat-generating substrate 1. The first substrate 5 is, for example, a PCB substrate, and has a driver IC 55 mounted thereon. The shape of the first substrate 5 is not particularly limited; in this embodiment, it is an elongated rectangle with the x direction as its longitudinal direction. The first substrate 5 has a first substrate main surface 51 and a first substrate back surface 52. The first substrate main surface 51 faces the same side as the heat-generating substrate main surface 11 of the heat-generating substrate 1, and the first substrate back surface 52 faces the same side as the heat-generating substrate back surface 12 of the heat-generating substrate 1. First wiring (not shown) is formed on the first substrate main surface 51. The driver IC 55 is die-bonded to the first wiring, and the wire 562 is wire-bonded to the first wiring. In this embodiment, a high-purity Au plating layer is formed by electrolytic plating on a Cu wiring, for example. The constituent material and formation method of the first wiring are not limited.

[0028] As shown in FIG. 6 , the first substrate rear surface 52 has a third region 52a and a fourth region 52b. The third region 52a is a region that is adhered to the heat dissipation member 8 (first support surface 81) via an adhesive member 85. The third region 52a has an elongated rectangular shape that is long in the x direction and is located at the center in the x direction and the center in the y direction. The fourth region 52b is a region that is adhered to the heat dissipation member 8 (first support surface 81) via an adhesive member 86. The fourth region 52b has an elongated rectangular ring shape that is long in the x direction and is located so as to surround the third region 52a and is located at both ends in the x direction and both ends in the y direction. The fourth region 52b does not overlap the third region 52a and does not overlap the adhesive member 85 when viewed in the z direction.

[0029] The driver IC 55 is mounted on the first substrate main surface 51 of the first substrate 5 and serves to individually energize the plurality of heat generating portions 41. In this embodiment, the driver IC 55 is conductively connected to the plurality of individual electrodes 31 by a plurality of wires 561. The energization control of the driver IC 55 is in accordance with a command signal input from outside the thermal printhead A1 via the first substrate 5, the second substrate 6, the third substrate 7, and the connector 69. The driver IC 55 is conductively connected to the first wiring of the first substrate 5 by a plurality of wires 562. In this embodiment, a plurality of driver ICs 55 is provided corresponding to the number of heat generating portions 41.

[0030] The driver IC 55, the plurality of wires 561, and the plurality of wires 562 are covered with a protective resin 57. The protective resin 57 is made of, for example, an insulating resin and is, for example, black. The protective resin 57 is formed so as to straddle the heat-generating substrate 1 and the first substrate 5.

[0031] As shown in FIGS. 1 and 4 , the second substrate 6 is disposed upstream in the y direction relative to the first substrate 5. The second substrate 6 is, for example, a PCB substrate, and is equipped with other circuit elements (not shown) and a connector 69. The shape of the second substrate 6 is not particularly limited; in this embodiment, it is an elongated rectangle with the x direction as its longitudinal direction. The second substrate 6 has a second substrate main surface 61 and a second substrate back surface 62. The second substrate main surface 61 faces the same side as the heat-generating substrate main surface 11 of the heat-generating substrate 1, and the second substrate back surface 62 faces the same side as the heat-generating substrate back surface 12 of the heat-generating substrate 1. However, in this embodiment, the second substrate 6 is disposed at an angle relative to the heat-generating substrate 1 and the first substrate 5. Furthermore, in this embodiment, the second substrate main surface 61 is located higher in the z direction than the first substrate main surface 51. Second wiring (not shown) is formed on the second substrate main surface 61 and the second substrate back surface 62. The material and method of forming the second wiring are not limited.

[0032] The connector 69 is used to connect the thermal printhead A1 to a printer (not shown) and is attached to the rear surface 62 of the second substrate, and is connected to the second wiring.

[0033] The third substrate 7 is connected to the first substrate 5 and the second substrate 6 and is more flexible than the first substrate 5 and the second substrate 6. The third substrate 7 is a flexible printed circuit board and is formed with third wiring that electrically connects the first wiring of the first substrate 5 and the second wiring of the second substrate 6. Because the first substrate 5 and the second substrate 6 are connected by the flexible third substrate 7, the second substrate 6 can be disposed in an inclined state with respect to the first substrate 5. The shape of the third substrate 7 is not particularly limited, and in this embodiment, it is an elongated rectangle with the x direction as the longitudinal direction.

[0034] The heat dissipation member 8 carries the heat-generating substrate 1, the first substrate 5, and the second substrate 6 and dissipates a portion of the heat generated by the multiple heat-generating portions 41 to the outside via the heat-generating substrate 1. The heat dissipation member 8 is a block-shaped member made of a metal such as aluminum and is formed, for example, by extrusion molding. The constituent material and method of the heat dissipation member 8 are not limited. As shown in FIG. 4 , the heat dissipation member 8 has a first support surface 81, a second support surface 82, and a bottom surface 83. The first support surface 81 and the second support surface 82 face opposite each other in the z direction, and the bottom surface 83 faces opposite each other in the z direction. The first support surface 81 and the second support surface 82 face upward in FIG. 4 and are arranged side by side in the y direction. As shown in FIG. 4 , the second support surface 82 is arranged farther from the bottom surface 83 than the first support surface 81 (upper in FIG. 4 ). The first support surface 81 is inclined with respect to the second support surface 82 and the bottom surface 83. The first support surface 81 may be parallel to the second support surface 82 and the bottom surface 83. The first support surface 81 and the second support surface 82 may be flush with each other.

[0035] The heat-generating substrate rear surface 12 of the heat-generating substrate 1 and the first substrate rear surface 52 of the first substrate 5 are adhered to the first support surface 81. As shown in Figures 7 and 8, an adhesive member 85 and a sticky member 86 are disposed on the first support surface 81 between the heat-generating substrate 1 and the first substrate 5.

[0036] The adhesive member 85 is interposed between the first region 12a of the heat-generating substrate rear surface 12 and the third region 52a of the first substrate rear surface 52 and the first support surface 81, and relatively firmly bonds the heat-generating substrate rear surface 12 and the first substrate rear surface 52 to the first support surface 81. The adhesive member 85 has relatively high thermal conductivity, at least higher than that of the adhesive member 86. The adhesive member 85 is, for example, a low-elasticity thermosetting adhesive, and includes, for example, a silicone-based adhesive. The constituent material of the adhesive member 85 is not limited.

[0037] The adhesive member 86 is interposed between the second region 12b of the heat-generating substrate rear surface 12 and the fourth region 52b of the first substrate rear surface 52 and the first support surface 81, and adheres the heat-generating substrate rear surface 12 and the first substrate rear surface 52 relatively loosely to the first support surface 81. In other words, the adhesive member 86 has a weaker adhesive strength than the adhesive member 85. The adhesive member 86 may be, for example, a so-called substrate-less double-sided tape. The substrate-less double-sided tape has release papers disposed on both sides of the thin-film adhesive member 86. One release paper is peeled off to attach the tape to the first support surface 81 of the heat dissipation member 8, and the other release paper is peeled off to reveal the adhesive member 86 alone. The constituent material of the adhesive member 86 is not limited. The adhesive member 86 may be, for example, a so-called double-sided tape including a thin-film substrate and an adhesive disposed on both sides of the substrate. The adhesive member 86 may also be an adhesive having a relatively high filler content and a relatively low adhesive component content, thereby weakening its adhesive strength.

[0038] The second substrate back surface 62 of the second substrate 6 is adhered to the second support surface 82. Note that the material of the adhesive member adhering the second substrate back surface 62 to the second support surface 82 is not limited. The bottom surface 83 faces downward in FIG. 4 . The bottom surface 83 is a reference surface when incorporating the thermal printhead A1 into a printer. The second support surface 82 is parallel to the bottom surface 83. In this specification, the thickness direction of the heat-generating substrate 1 is defined as the z direction, so the first support surface 81 is perpendicular to the z direction. On the other hand, the second support surface 82 is inclined with respect to a plane perpendicular to the z direction (the first support surface 81), and is therefore not perpendicular to the z direction. Similarly, the bottom surface 83 is not perpendicular to the z direction.

[0039] Next, an example of a method for manufacturing the thermal printhead A1 will be described below with reference to Figures 9 to 12. Figures 9 to 12 are cross-sectional views showing one step of the example of the method for manufacturing the thermal printhead A1, and correspond to the cross sections shown in Figures 4 and 5. Note that the x, y, and z directions shown in Figures 9 to 12 are the same as those in Figures 1 to 8.

[0040] First, a heat generating substrate 1 is prepared as shown in Fig. 9. The heat generating substrate 1 is formed by forming the heat generating substrate main surface 11 and the convex portions 13 by anisotropically etching a substrate material made of a single crystal semiconductor such as a Si wafer, and then cutting the substrate into individual pieces.

[0041] 10, an insulating layer 18, a resistor layer 4, and a conductive layer 3 are formed. The insulating layer 18 is formed by depositing TEOS on the heating substrate main surface 11 and the protrusions 13, for example, by CVD. The resistor layer 4 and the conductive layer 3 are formed by forming a resistor film on the insulating layer 18, for example, by sputtering, forming a conductive film covering the resistor film, and selectively etching the conductive film and the resistor film.

[0042] Next, the protective layer 2 is formed by depositing SiN and SiC on the insulating layer 18, the conductive layer 3, and the resistor layer 4 using, for example, CVD. The protective layer 2 is then partially removed by etching or the like to form pad openings 21. In this manner, the heating substrate 1 on which each layer is formed is obtained.

[0043] In addition to the processing of the heat-generating substrate 1, a first substrate 5, a second substrate 6, and a third substrate 7 are prepared. The first substrate 5 is a PCB substrate on which a first wiring is formed. The second substrate 6 is a PCB substrate on which a second wiring is formed and on which a connector 69 is mounted. The third substrate 7 is a flexible printed circuit board on which a third wiring is formed.

[0044] Next, as shown in FIG. 11 , the heat-generating substrate 1 and the first substrate 5 are assembled. First, the heat-generating substrate 1 and the first substrate 5 are placed on the support tape 95 with a predetermined gap between them. Next, the driver IC 55 is mounted on the first substrate main surface 51 of the first substrate 5, and multiple wires 561 and 562 are bonded thereto. A protective resin 57 covering the driver IC 55 and the multiple wires 561 and 562 is then formed across the heat-generating substrate 1 and the first substrate 5. Heat is applied to solidify the protective resin 57, and the first substrate 5, which has a higher linear expansion coefficient than the heat-generating substrate 1, expands. The heat-generating substrate 1 and the first substrate 5 are then fixed together by the protective resin 57. Then, upon cooling, the first substrate 5 contracts more than the heat-generating substrate 1, causing both ends of the heat-generating substrate 1 in the x direction to bend upstream in the y direction. The third substrate 7 is then bonded to the second substrate main surface 61 of the second substrate 6 with an adhesive or the like, thereby assembling the second substrate 6 and the third substrate 7. Next, the downstream portion of the third substrate 7 in the y direction is bonded with adhesive or the like to the upstream side in the y direction of the first substrate main surface 51 of the first substrate 5 that has been peeled off from the support tape 95 .

[0045] Next, the thermal printhead A1 is assembled.

[0046] First, a heat dissipation member 8 is prepared, which has a first support surface 81, a second support surface 82, and a bottom surface 83. The heat dissipation member 8 is formed by extrusion molding using a metal material such as aluminum. Next, an adhesive member 85 and a pressure-sensitive adhesive member 86 are placed on the first support surface 81 of the heat dissipation member 8 (see FIG. 7 ). At this time, an adhesive member is also placed on the second support surface 82.

[0047] Next, as shown in FIG. 12 , the integrated heat-generating substrate 1, first substrate 5, and second substrate 6 are attached to the heat dissipation member 8. The heat-generating substrate 1 is disposed downstream of the first support surface 81 in the y direction, with the heat-generating substrate rear surface 12 facing the first support surface 81. At this time, the first region 12a of the heat-generating substrate rear surface 12 faces the adhesive member 85, and the second region 12b faces the adhesive member 86. The first substrate 5 is disposed upstream of the first support surface 81 in the y direction, with the first substrate rear surface 52 facing the first support surface 81. At this time, the third region 52a of the first substrate rear surface 52 faces the adhesive member 85, and the fourth region 52b faces the adhesive member 86. The second substrate 6 is disposed with the second substrate rear surface 62 facing the second support surface 82. The first substrate 5 is connected to the second substrate 6 by the flexible third substrate 7, so that its tilt position relative to the second substrate 6 can be freely changed. Therefore, the first substrate 5 can be attached to the first support surface 81 that is inclined relative to the second support surface 82. Next, heat is applied to solidify the adhesive member 85, thereby bonding the heating substrate rear surface 12 and the first substrate rear surface 52 to the first support surface 81.

[0048] The thermal printhead A1 described above is obtained through the above steps. The method for manufacturing the thermal printhead A1 is not limited to the method described above. For example, the order in which the thermal printhead A1 is assembled is not limited. The thermal printhead A1 may be assembled by attaching the heat-generating substrate 1 and the first substrate 5, which are integrated by the protective resin 57, to the heat dissipation member 8, and then attaching the second substrate 6 to the heat dissipation member 8, and connecting the third substrate 7 to the first substrate 5.

[0049] Next, the operation of the thermal printhead A1 will be described.

[0050] According to this embodiment, in the assembly process of the thermal printhead A1, the heating substrate 1 is placed on the first support surface 81 of the heat dissipation member 8 so that the first region 12a of the heating substrate rear surface 12 faces the adhesive member 85 and the second region 12b faces the adhesive member 86. Then, heat is applied to solidify the adhesive member 85. This heating causes the first substrate 5, which has a higher linear expansion coefficient than the heating substrate 1, to expand, thereby correcting the curvature of the heating substrate 1. At this time, the second regions 12b located at both ends of the heating substrate rear surface 12 in the x direction are adhered to the first support surface 81 relatively gently by the adhesive member 86. Therefore, compared to when the second region 12b is adhered by the adhesive member 85, the internal stress at the curved portion of the heating substrate 1 is more easily released. Therefore, the curvature of the heating substrate 1 is more easily corrected. As a result, the thermal printhead A1 can suppress curvature of the heating substrate 1 compared to when the second region 12b of the heating substrate rear surface 12 is also adhered by the adhesive member 85.

[0051] Furthermore, in this embodiment, the second region 12b is adhered to the heat dissipation member 8 via the adhesive member 86, which has a weaker adhesive strength than the adhesive member 85. Therefore, in the manufacturing process, it is possible to prevent the position of the heat-generating substrate 1 from shifting until the adhesive member 85 solidifies.

[0052] Furthermore, according to this embodiment, in the assembly process of the thermal printhead A1, the first substrate 5 is placed on the first support surface 81 of the heat dissipation member 8 so that the third region 52a of the first substrate back surface 52 faces the adhesive member 85 and the fourth region 52b faces the adhesive member 86. Then, by applying heat, the adhesive member 85 is solidified. The fourth regions 52b, located at both ends of the first substrate back surface 52 in the x direction, are adhered relatively gently to the first support surface 81 by the adhesive member 86. Therefore, the first substrate 5 is not hindered from expanding due to heating, compared to when the fourth region 52b is also adhered by the adhesive member 85. As a result, the curvature of the heating substrate 1 of the thermal printhead A1 is easily corrected.

[0053] Furthermore, according to the present embodiment, the fourth region 52b is adhered to the heat dissipation member 8 via the adhesive member 86, which has a weaker adhesive strength than the adhesive member 85. Therefore, in the manufacturing process, it is possible to prevent the position of the first substrate 5 from shifting until the adhesive member 85 solidifies.

[0054] Furthermore, according to this embodiment, the adhesive member 85 has relatively high thermal conductivity and contains the plurality of heat generating portions 41 when viewed in the z direction. As a result, the heat generated by the plurality of heat generating portions 41 is appropriately dissipated to the heat dissipation member 8 via the adhesive member 85.

[0055] Furthermore, in this embodiment, a so-called substrate-less double-sided tape is used as the adhesive member 86. This allows the adhesive member 86 to adhere the heat-generating substrate rear surface 12 and the first substrate rear surface 52 to the first support surface 81 relatively loosely. Furthermore, compared to directly arranging the adhesive member 86, the adhesive member 86 is easier to arrange. Furthermore, the adhesive member 86 (substrate-less double-sided tape) has higher thermal conductivity than double-sided tape that includes a substrate, and therefore can appropriately dissipate heat from the heat-generating substrate 1 to the heat dissipation member 8.

[0056] Furthermore, according to this embodiment, the heating substrate 1 has protrusions 13 that protrude in the z-direction from the heating substrate main surface 11, and the multiple heating elements 41 are arranged on the protrusions 13. This allows the thermal printhead A1 to appropriately press the print medium against the heating elements 41 via the platen roller 91. Furthermore, according to this embodiment, the heating substrate 1 is made from a substrate material made of a single-crystal semiconductor such as a Si wafer. Therefore, the heating substrate 1 can easily be anisotropically etched to form protrusions 13 with a uniform cross section perpendicular to the x-direction.

[0057] Furthermore, in this embodiment, the first substrate 5 and the second substrate 6 are connected by the flexible third substrate 7. Therefore, the first substrate 5 and the second substrate 6 can be mounted on the heat dissipation member 8 while tilted relative to each other, thereby improving the degree of freedom in the design of the thermal printhead A1.

[0058] In this embodiment, the heating substrate 1 is made of a single crystal semiconductor, but the present invention is not limited to this. The material of the heating substrate 1 is not limited, and may be, for example, ceramics.

[0059] 13 to 15 show other embodiments of the present disclosure. In these figures, elements that are the same as or similar to those in the above embodiment are denoted by the same reference numerals as those in the above embodiment.

[0060] Second Embodiment: Figures 13 and 14 are diagrams illustrating a thermal printhead A2 according to a second embodiment of the present disclosure. Figure 13 is a plan view showing the heat dissipation member 8 of the thermal printhead A2, and corresponds to Figure 7. Figure 14 is a cross-sectional view taken along line XIV-XIV in Figure 13. The thermal printhead A2 of this embodiment differs from the above-described embodiment in that it does not include an adhesive member 86. The configuration and operation of other parts of this embodiment are similar to those of the first embodiment. Note that the various parts of the first embodiment described above may be combined in any desired manner.

[0061] In this embodiment, no adhesive member 86 is disposed on the first support surface 81 of the heat dissipation member 8 between the heat generating substrate rear surface 12 of the heat generating substrate 1 and the first substrate rear surface 52 of the first substrate 5. The heat generating substrate rear surface 12 and the first substrate rear surface 52 are adhered to the first support surface 81 of the heat dissipation member 8 only by the adhesive member 85.

[0062] According to this embodiment, the second region 12b of the heating substrate rear surface 12 is not bonded to the first support surface 81. Therefore, the internal stress in the curved portion of the heating substrate 1 is more easily released than when the second region 12b is bonded with the adhesive member 85. Because the curvature of the heating substrate 1 is more easily corrected, the thermal printhead A2 can suppress curvature of the heating substrate 1 more effectively than when the second region 12b of the heating substrate rear surface 12 is also bonded with the adhesive member 85. Furthermore, according to this embodiment, the fourth region 52b of the first substrate rear surface 52 is not bonded to the first support surface 81. Therefore, the first substrate 5 is not hindered from expanding due to heating, as compared to when the fourth region 52b is also bonded with the adhesive member 85. As a result, the curvature of the heating substrate 1 is more easily corrected in the thermal printhead A2. Furthermore, according to this embodiment, the adhesive member 86 is not required, simplifying the manufacturing process. Furthermore, the thermal printhead A2 has the same configuration as the thermal printhead A1, and therefore exhibits the same effects as the thermal printhead A1.

[0063] Third Embodiment: Figure 15 is a diagram illustrating a thermal printhead A3 according to a third embodiment of the present disclosure. Figure 15 is a plan view showing the heat dissipation member 8 of the thermal printhead A3, and corresponds to Figure 7. The thermal printhead A3 of this embodiment differs from the above-described embodiments in that the entire surface (or substantially the entire surface) of the first substrate rear surface 52 is adhered to the first support surface 81 by an adhesive member 86. The configuration and operation of other parts of this embodiment are similar to those of the first embodiment. Note that the parts of the first and second embodiments may be combined in any desired manner.

[0064] In this embodiment, no adhesive member 85 is disposed between the first support surface 81 of the heat dissipation member 8 and the first substrate back surface 52 of the first substrate 5, and the entire surface (or substantially the entire surface) of the first substrate back surface 52 is adhered to the first support surface 81 by the adhesive member 86. The first substrate back surface 52 is adhered to the first support surface 81 of the heat dissipation member 8 only by the adhesive member 86.

[0065] In this embodiment, the second region 12b of the heat generating substrate rear surface 12 is also bonded relatively loosely to the first support surface 81 by the adhesive member 86. Therefore, the internal stress in the curved portion of the heat generating substrate 1 is more easily released than when the second region 12b is bonded by the adhesive member 85. Because the curvature of the heat generating substrate 1 is more easily corrected, the thermal printhead A3 can suppress curvature of the heat generating substrate 1 compared to when the second region 12b of the heat generating substrate rear surface 12 is also bonded by the adhesive member 85. Furthermore, in this embodiment, the entire surface (or substantially the entire surface) of the first substrate rear surface 52 is bonded to the first support surface 81 by the adhesive member 86. Therefore, expansion of the first substrate 5 due to heating is less hindered than when the first substrate 5 is bonded by the adhesive member 85. As a result, the curvature of the heat generating substrate 1 is more easily corrected in the thermal printhead A3. Furthermore, in this embodiment, there is no need to dispose the adhesive member 85 between the first support surface 81 and the first substrate rear surface 52, which simplifies the manufacturing process. Furthermore, the thermal printhead A3 has the same configuration as the thermal printhead A1, and therefore exhibits the same effects as the thermal printhead A1.

[0066] The thermal printhead according to the present disclosure is not limited to the above-described embodiment. The specific configuration of each part of the thermal printhead according to the present disclosure can be freely modified in various ways. The present disclosure includes the embodiments described in the following appendices.

[0067] Supplementary Note 1. A thermal printhead (A1) comprising: a heat-generating substrate (1) having a heat-generating substrate main surface (11) and a heat-generating substrate back surface (12) facing opposite each other in the thickness direction (z direction); a plurality of heat-generating portions (41) disposed on the heat-generating substrate main surface side and arranged along the main scanning direction (x direction); and a heat dissipation member (8) on which the heat-generating substrate is mounted, wherein the back surface of the heat-generating substrate has: a first region (12a) located in the center in the main scanning direction and adhered to the heat dissipation member via an adhesive member (85); and second regions (12b) located at both ends in the main scanning direction and not overlapping with the adhesive member as viewed in the thickness direction. Supplementary Note 2. The thermal printhead according to Supplementary Note 1, wherein the plurality of heat-generating portions overlap with the first region as viewed in the thickness direction. Supplementary Note 3. The thermal printhead according to Supplementary Note 2, wherein the plurality of heat-generating portions are contained within the first region as viewed in the thickness direction. Supplementary Note 4. A thermal printhead according to any one of Supplementary Notes 1 to 3, wherein the adhesive member includes a silicone-based adhesive.Supplementary Note 5. A thermal printhead according to any one of Supplementary Notes 1 to 4, wherein the second region is adhered to the heat dissipation member via an adhesive member (86) having a weaker adhesive strength than the adhesive member.Supplementary Note 6. (Fig. 8) A thermal printhead according to Supplementary Note 5, wherein the adhesive member is a substrate-less double-sided tape.Supplementary Note 7. A thermal printhead according to Supplementary Note 5 or 6, wherein the adhesive member has a higher thermal conductivity than the adhesive member.Supplementary Note 8. A thermal printhead according to any one of Supplementary Notes 1 to 7, further comprising a first substrate (5) having a first substrate main surface (51) and a first substrate back surface (52) facing opposite each other in the thickness direction, and mounted on the heat dissipation member, aligned in the sub-scanning direction (y direction) of the heat-generating substrate.Supplementary Note 9. A thermal printhead as described in Appendix 8, wherein the rear surface of the first substrate has: a third region (52a) located in the center in the main scanning direction and adhered to the heat dissipation member via the adhesive member; and a fourth region (52b) located at both ends in the main scanning direction and not overlapping the adhesive member.Appendix 10. The thermal printhead of Appendix 9, wherein the fourth region is located on both sides of the third region in the sub-scanning direction. Appendix 11. The thermal printhead of Appendix 9 or 10, wherein the fourth region is adhered to the heat dissipation member via a second adhesive member (86) having a weaker adhesive strength than the adhesive member. Appendix 12. The thermal printhead of any of Appendixes 1 to 11, wherein the heat generating substrate contains Si. Appendix 13. The thermal printhead of Appendix 12, wherein the main surface of the heat generating substrate is a (100) plane. Appendix 14. The thermal printhead of any of Appendixes 1 to 13, wherein the heat generating substrate has convex portions (13) protruding from the main surface of the heat generating substrate and extending in the main scanning direction, and the plurality of heat generating portions are arranged on the convex portions.

[0068] A1 to A3: Thermal printhead 1: Heat-generating substrate 11: Main surface of heat-generating substrate 12: Back surface of heat-generating substrate 12a: First region 12b: Second region 13: Convex portion 18: Insulating layer 2: Protective layer 21: Pad opening 3: Conductive layer 31: Individual electrode 311: Individual pad 32: Common electrode 323: Connecting portion 324: Strip-shaped portion 33: Relay electrode 4: Resistor layer 41: Heat-generating portion 5: First substrate 51: First substrate main surface 52: Back surface of first substrate 52a: Third region 52b: Fourth region 55: Driver IC 561, 562: Wire 57: Protective resin 6: Second substrate 61: Second substrate main surface 62: Back surface of second substrate 69: Connector 7: Third substrate 8: Heat dissipation member 81: First support surface 82: Second support surface 83: Bottom surface 85: Adhesive member 86: Sticky member 91: Platen roller 95: Support tape

Claims

1. a heat generating substrate having a main surface and a rear surface facing in opposite directions in a thickness direction; A plurality of heat generating portions are disposed on a main surface side of the heat generating substrate and arranged along a main scanning direction; a heat dissipation member on which the heat generating substrate is mounted; Equipped with The rear surface of the heat generating substrate is a first region located at a center in the main scanning direction and bonded to the heat dissipation member via an adhesive member; a second region located at both ends in the main scanning direction and not overlapping the adhesive member when viewed in the thickness direction; A thermal print head comprising:

2. The thermal printhead according to claim 1 , wherein the plurality of heat generating portions overlap the first region when viewed in the thickness direction.

3. The thermal printhead according to claim 2 , wherein the plurality of heat generating portions are contained within the first region when viewed in the thickness direction.

4. The thermal printhead of claim 1 , wherein the adhesive member includes a silicone adhesive.

5. 5. The thermal printhead according to claim 1, wherein the second region is adhered to the heat dissipation member via an adhesive member having a weaker adhesive strength than the adhesive member.

6. The thermal printhead according to claim 5 , wherein the adhesive member is a substrate-less double-sided tape.

7. The thermal printhead according to claim 5 , wherein the adhesive member has a higher thermal conductivity than the pressure-sensitive adhesive member.

8. 5. A thermal printhead as described in claim 1, further comprising a first substrate having a first substrate main surface and a first substrate back surface facing opposite each other in the thickness direction, and mounted on the heat dissipation member, aligned in the sub-scanning direction of the heat-generating substrate.

9. The rear surface of the first substrate is a third region located at a center in the main scanning direction and bonded to the heat dissipation member via the adhesive member; a fourth region located at both ends in the main scanning direction and not overlapping the adhesive member; The thermal printhead of claim 8 .

10. The thermal printhead according to claim 9 , wherein the fourth region is located on both sides of the third region in the sub-scanning direction.

11. The thermal printhead according to claim 9 , wherein the fourth region is adhered to the heat dissipation member via a second adhesive member having a weaker adhesive strength than the adhesive member.

12. 5. The thermal printhead according to claim 1, wherein the heat generating substrate comprises Si.

13. The thermal printhead of claim 12 , wherein the main surface of the heat generating substrate is a (100) surface.

14. the heat generating substrate has a protrusion protruding from a main surface of the heat generating substrate and extending in the main scanning direction, 5. The thermal printhead according to claim 1, wherein the plurality of heat generating portions are arranged on the convex portion.