Thermal printing head, thermal printing system, and method for manufacturing thermal printing head

Abstract

A thermal printing head according to the present invention comprises a substrate, a first insulating film, and a second insulating film. The substrate has a first main surface and a second main surface on the reverse surface from the first main surface. A protruding portion that protrudes toward the side opposite the second main surface is formed on the first main surface. A recessed section is formed in the surface of the protruding portion. The first insulating film is disposed on the first main surface so as to cover the protruding portion. The second insulating film is disposed on a surface with the first insulating film interposed therebetween. A through hole is formed in a portion of the first insulating film that faces the bottom surface of the recessed section with a gap therebetween.

Description

Thermal printhead, thermal printing system, and method for manufacturing thermal printhead

[0001] The present disclosure relates to a thermal printhead, a thermal printing system, and a method for manufacturing a thermal printhead.

[0002] For example, Japanese Patent Laid-Open No. 2019-14233 (Patent Document 1) describes a thermal printhead that includes a substrate, an insulating film, a resistor layer, a wiring layer, and a protective film.

[0003] The substrate has a first main surface and a second main surface. The second main surface is the opposite surface of the first main surface. A raised portion is formed on the first main surface. The raised portion is raised toward the side opposite the second main surface. The raised portion extends in a first direction in a plan view. An insulating film is disposed on the first main surface so as to cover the raised portion. A wiring layer is disposed on the insulating film with a resistor layer interposed therebetween.

[0004] The wiring layer has a plurality of wiring portions. The plurality of wiring portions are arranged at intervals along a first direction. Each of the plurality of wiring portions extends in a second direction perpendicular to the first direction so as to overlap with a protruding portion. The resistor layer has a heater portion. Each of the plurality of wiring portions is partially removed above the heater portion. A protective film is disposed on the insulating film so as to cover the wiring layer and the resistor layer.

[0005] The paper to be printed is placed between the protective film above the heater and the platen roller. When printing, a current flows through each of the multiple wiring sections. When this current flows through the heater, the heater generates resistance heat. This heat is transferred to the paper, allowing printing to occur on the paper.

[0006] Japanese Patent Application Laid-Open No. 2019-14233

[0007] [Summary] Heat generated in the heater section is not only transferred to the paper being printed on, but also dissipated via the insulating film and the raised portion. In other words, the thermal printhead described in Patent Document 1 leaves room for improvement in the efficiency of heat utilization generated in the heater section.

[0008] The thermal printhead of the present disclosure includes a substrate, a first insulating film, and a second insulating film. The substrate has a first main surface and a second main surface opposite the first main surface. A raised portion is formed on the first main surface, rising on the side opposite the second main surface. A recess is formed on the surface of the raised portion. The first insulating film is disposed on the first main surface so as to cover the raised portion. The second insulating film is disposed on the surface with the first insulating film interposed therebetween. A through-hole is formed in a portion of the first insulating film that faces the bottom surface of the recess with a gap therebetween.

[0009] 1. A plan view of a thermal printhead 100. A cross-sectional view taken along line II-II in FIG. 1. A cross-sectional view taken along line III-III in FIG. 1. A manufacturing process diagram of a thermal printhead 100. A cross-sectional view illustrating a hard mask forming step S21. A cross-sectional view illustrating a first etching step S22. A cross-sectional view illustrating a second etching step S23. A cross-sectional view illustrating a first insulating film forming step S3. A cross-sectional view illustrating a through-hole forming step S4. A cross-sectional view illustrating a recess forming step S5. A cross-sectional view illustrating a second insulating film forming step S6. A cross-sectional view illustrating a film forming step S7. A cross-sectional view illustrating a first etching step S8. A cross-sectional view illustrating a second etching step S9. A cross-sectional view illustrating a third etching step S10. A cross-sectional view of a thermal printhead 100 according to a modified example. A cross-sectional view of a thermal printhead 200. A manufacturing process diagram of a thermal printhead 200. A cross-sectional view of a thermal printhead 200 according to a modified example. A schematic diagram of a thermal printing system 300.

[0010] [DETAILED DESCRIPTION] The details of the embodiments of the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are designated by the same reference numerals, and redundant descriptions will not be repeated.

[0011] First Embodiment A thermal printhead according to the first embodiment will be described. The thermal printhead according to the first embodiment is designated as a thermal printhead 100.

[0012] <Configuration of Thermal Printhead 100> The configuration of the thermal printhead 100 will be described below.

[0013] FIG. 1 is a plan view of a thermal printhead 100. In FIG. 1, the protective film 60 is omitted. Also, in FIG. 1, the raised portion 11 is indicated by a dotted line. FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1. As shown in FIGS. 1 to 3, the thermal printhead 100 has a substrate 10, an insulating film 20, an insulating film 30, a resistor layer 40, a wiring layer 50, and a protective film 60.

[0014] The substrate 10 has a main surface 10a and a main surface 10b. The main surfaces 10a and 10b are end surfaces of the substrate 10 in the thickness direction. The main surface 10b is the surface opposite to the main surface 10a. A raised portion 11 is formed on the main surface 10a. The raised portion 11 extends along a first direction DR1 in a plan view. Note that the plan view refers to the case where the thermal printhead 100 is viewed along the normal direction of the main surface 10a. The raised portion 11 is raised toward the side opposite the main surface 10b.

[0015] In a cross-sectional view perpendicular to the first direction DR1, the protrusion 11 has a top surface, two first side surfaces, and two second side surfaces. The two first side surfaces form end surfaces of the protrusion 11 in the second direction DR2. The second direction DR2 is a direction perpendicular to the first direction DR1 in a plan view. The distance between the two first side surfaces increases with increasing distance from the top surface. The second side surfaces are continuous with the top surface at their upper ends and with the first side surfaces at their lower ends. A recess 11a is formed on the surface of the protrusion 11. More specifically, the recess 11a is formed on the second side surface of the protrusion 11. The constituent material of the substrate 10 is, for example, single-crystal silicon.

[0016] The insulating film 20 is disposed on the main surface 10a so as to cover the protrusion 11. A through hole 21 is formed in a portion of the insulating film 20 that faces the bottom surface of the recess 11a with a gap therebetween. The through hole 21 penetrates the insulating film 20 in the thickness direction. From another perspective, the through hole 21 communicates with the recess 11a. The opening diameter of the through hole 21 is, for example, equal to or less than the thickness of the insulating film 30. The opening diameter of the through hole 21 is preferably 2 μm or less. The constituent material of the insulating film 20 is, for example, silicon oxide.

[0017] The insulating film 30 is disposed on the insulating film 20. That is, the insulating film 30 is disposed on the surface of the protrusion 11 with the insulating film 20 interposed therebetween. The through-hole 21 is closed by the insulating film 30. The insulating film 30 is made of, for example, silicon oxide. The insulating film 30 is preferably a plasma CVD (Chemical Vapor Deposition) film. The plasma CVD film is a film formed by plasma CVD.

[0018] The wiring layer 50 is disposed on the insulating film 30 with the resistor layer 40 interposed therebetween. The resistor layer 40 is made of, for example, tantalum nitride. Although not shown, an intermediate layer may be interposed between the resistor layer 40 and the wiring layer 50. The intermediate layer is made of, for example, titanium.

[0019] The wiring layer 50 has a plurality of wiring portions 51 and connection portions 52. The plurality of wiring portions 51 are arranged at intervals along the first direction DR1. The wiring portions 51 extend along the second direction DR2 so as to overlap the protrusions 11 in a plan view.

[0020] The multiple wiring portions 51 include multiple wiring portions 51a and multiple wiring portions 51b. The wiring portions 51a and the wiring portions 51b are alternately arranged in the first direction DR1. One end of the wiring portion 51a (the upper end in FIG. 1) and one end of the wiring portion 51b (the upper end in FIG. 1) are connected to each other. The other end of the wiring portion 51a is connected to a connection portion 52. The connection portion 52 extends along the first direction DR1. The wiring layer 50 is made of a material such as copper or a copper alloy.

[0021] The resistor layer 40 has a heater portion 41. The heater portion 41 is located above the portion of the insulating film 20 where the through-hole 21 is formed. In other words, the heater portion 41 is located at a position overlapping the recess 11a. The wiring portion 51 (and the intermediate layer) is partially removed above the heater portion 41. From another perspective, the heater portion 41 is exposed from the wiring portion 51.

[0022] The protective film 60 is disposed on the insulating film 30 so as to cover the resistor layer 40 and the wiring layer 50. Although not shown, the protective film 60 has a plurality of first openings and a plurality of second openings formed therein. The other end of each of the plurality of wiring portions 51b is exposed from each of the plurality of first openings. A portion of the connection portion 52 is exposed from the second opening. Bonding pads are formed on the other end of the wiring portion 51b exposed from the first opening and on the connection portion 52 exposed from the second opening. The bonding pads include, for example, a nickel layer, a palladium layer disposed on the nickel layer, and a gold layer disposed on the palladium layer. The protective film 60 is made of, for example, silicon nitride.

[0023] <Method of Manufacturing Thermal Printhead 100> A method of manufacturing the thermal printhead 100 will now be described.

[0024] 4 is a manufacturing process diagram of the thermal printhead 100. As shown in FIG. 4, the manufacturing method of the thermal printhead 100 includes a preparation step S1, a protrusion formation step S2, a first insulating film formation step S3, a through-hole formation step S4, a recess formation step S5, a second insulating film formation step S6, a film deposition step S7, a first etching step S8, a second etching step S9, a third etching step S10, a protective film formation step S11, and a pad formation step S12.

[0025] In the preparation step S1, the substrate 10 is prepared. After the preparation step S1, a bump formation step S2 is performed. The bump formation step S2 includes a hard mask formation step S21, a first etching step S22, and a second etching step S23. The first etching step S22 is performed after the hard mask formation step S21, and the second etching step S23 is performed after the first etching step S22.

[0026] 5 is a cross-sectional view illustrating the hard mask formation step S21. As shown in FIG. 5, in the hard mask formation step S21, a hard mask HM is formed on the portion of the main surface 10a where the protrusion 11 is to be formed. The hard mask HM is also formed on the main surface 10b.

[0027] In the hard mask formation step S21, first, a film of the constituent material of the hard mask HM is formed on the surface of the substrate 10 by, for example, low-pressure CVD. Second, a resist pattern is formed on the constituent material of the hard mask HM formed on the main surface 10a. Third, using the resist pattern as a mask, anisotropic etching such as RIE (reactive ion etching) is performed on the constituent material of the hard mask HM formed on the main surface 10a, thereby patterning the constituent material of the hard mask HM formed on the main surface 10a. After the hard mask HM is formed, the resist pattern is removed.

[0028] 6 is a cross-sectional view illustrating the first etching step S22. As shown in FIG. 6, in the first etching step S22, the protrusion 11 is formed by wet etching using the hard mask HM as a mask. After the first etching step S22, the protrusion 11 has a top surface and a first side surface, but does not have a second side surface. A potassium hydroxide aqueous solution is used as an etchant for the wet etching. After the wet etching, the hard mask HM is removed using, for example, a hydrofluoric acid aqueous solution.

[0029] 7 is a cross-sectional view illustrating the second etching step S23. As shown in Fig. 7, in the second etching step S23, wet etching is further performed to form second side surfaces at the corners formed by the top surfaces of the protrusions 11 and the side surfaces of the protrusions 11. For the wet etching, a TMAH (tetramethylammonium hydroxide) aqueous solution is used as an etching solution.

[0030] After the protrusion forming step S2, a first insulating film forming step S3 is performed. Fig. 8 is a cross-sectional view illustrating the first insulating film forming step S3. As shown in Fig. 8, in the first insulating film forming step S3, an insulating film 20 is formed. The insulating film 20 is formed by, for example, performing thermal oxidation on the substrate 10.

[0031] After the first insulating film forming step S3, a through-hole forming step S4 is performed. Fig. 9 is a cross-sectional view illustrating the through-hole forming step S4. As shown in Fig. 9, in the through-hole forming step S4, a through-hole 21 is formed in the insulating film 20. In the through-hole forming step S4, first, a resist pattern is formed on the insulating film 20. Second, anisotropic dry etching is performed on the insulating film 20 using the resist pattern as a mask, thereby forming the through-hole 21. The resist pattern is removed after the dry etching.

[0032] After the through-hole forming step S4, a recess forming step S5 is performed. FIG. 10 is a cross-sectional view illustrating the recess forming step S5. As shown in FIG. 10, in the recess forming step S5, recesses 11a are formed in the surface of the protrusion 11. In the recess forming step S5, first, anisotropic dry etching is performed using the insulating film 20 as a mask, thereby forming holes in the surface of the protrusion 11 exposed from the through-hole 21. The depth of the holes is adjusted so that the constituent material of the substrate 10 does not remain between the bottom surface of the recesses 11a and the insulating film 20 after the isotropic dry etching described below is performed. Second, isotropic dry etching is performed using the insulating film 20 as a mask, thereby causing the holes formed by the anisotropic dry etching to extend in the direction along the surface of the protrusion 11 (lateral direction) and connect to each other to form the recesses 11a.

[0033] After the recess formation step S5, a second insulating film formation step S6 is performed. Fig. 11 is a cross-sectional view illustrating the second insulating film formation step S6. As shown in Fig. 11, in the second insulating film formation step S6, an insulating film 30 is formed by, for example, a plasma CVD method.

[0034] After the second insulating film forming step S6, a film forming step S7 is performed. Fig. 12 is a cross-sectional view illustrating the film forming step S7. As shown in Fig. 12, in the film forming step S7, the constituent material of the resistor layer 40, the constituent material of the intermediate layer, and the constituent material of the wiring layer 50 are sequentially formed by, for example, sputtering.

[0035] After the film forming step S7, a first etching step S8 is performed. Fig. 13 is a cross-sectional view illustrating the first etching step S8. As shown in Fig. 13, in the first etching step S8, the constituent material of the wiring layer 50 is patterned to form wiring portions 51 and connection portions 52 (not shown in Fig. 13).

[0036] In the first etching step S8, first, a resist pattern is formed on the constituent material of the deposited wiring layer 50. Second, the constituent material of the deposited wiring layer 50 is patterned by, for example, wet etching using the resist pattern as a mask. After the constituent material of the deposited wiring layer 50 has been patterned, the resist pattern is removed. In the first etching step S8, after the constituent material of the deposited wiring layer 50 has been patterned, wet etching is performed using the wiring layer 50 as a mask, thereby removing the intermediate layer other than that under the wiring layer 50.

[0037] After the first etching step S8, a second etching step S9 is performed. FIG. 14 is a cross-sectional view illustrating the second etching step S9. As shown in FIG. 14, in the second etching step S9, the wiring portion 51 on the heater portion 41 is partially removed. In the second etching step S9, first, a resist pattern is formed on the wiring layer 50. The resist pattern has an opening above the heater portion 41. Second, wet etching is performed using the resist pattern as a mask, thereby partially removing the wiring portion 51 on the heater portion 41. At this time, the intermediate layer on the heater portion 41 is also partially removed. The resist pattern is removed after the wet etching.

[0038] After the second etching step S9, a third etching step S10 is performed. FIG. 15 is a cross-sectional view illustrating the third etching step S10. As shown in FIG. 15, in the third etching step S10, the resistor layer 40 is removed except for the portion of the resistor layer 40 forming the heater portion 41 and the portion of the resistor layer 40 located below the wiring portion 51. In the third etching step S10, first, a resist pattern is formed. Second, the resistor layer 40 is removed by anisotropic dry etching such as RIE using the resist pattern as a mask.

[0039] After the third etching step S10, a protective film forming step S11 is performed. In the protective film forming step S11, a protective film 60 is formed. In the protective film forming step S11, first, a constituent material of the protective film 60 is deposited by, for example, a CVD method so as to cover the resistor layer 40 and the wiring layer 50. Second, a resist pattern is formed on the constituent material of the deposited protective film 60. Third, anisotropic dry etching such as RIE is performed using the resist pattern as a mask, thereby forming a first opening and a second opening.

[0040] The protective film forming step S11 is followed by the pad forming step S12. In the pad forming step S12, bonding pads are formed by, for example, electroless plating on the other end of the wiring portion 51b exposed from the first opening of the protective film 60 and on a part of the connection portion 52 exposed from the second opening of the protective film 60. In this way, the thermal printhead 100 having the structure shown in FIGS. 1 to 3 is formed.

[0041] <Modification> FIG. 16 is a cross-sectional view of a thermal printhead 100 according to a modification. As shown in FIG. 16, the insulating film 20 may be composed of multiple layers. For example, the insulating film 20 may be composed of a first layer 20a and a second layer 20b. The first layer 20a is disposed on the main surface 10a so as to cover the protrusion 11. The second layer 20b is disposed on the first layer 20a. The materials constituting the first layer 20a and the second layer 20b are, for example, silicon oxide and silicon nitride, respectively. Note that when the insulating film 20 is composed of the first layer 20a and the second layer 20b, in the first insulating film formation step S3, the first layer 20a is formed by, for example, thermal oxidation, and then the second layer 20b is formed by, for example, CVD.

[0042] <Advantages of Thermal Printhead 100> The advantages of the thermal printhead 100 will be described below.

[0043] In the thermal printhead 100, recesses 11a are formed on the surfaces of the protuberances 11, which separates the insulating film 20 below the heater section 41 from the surfaces of the protuberances 11, making it difficult for heat generated in the heater section 41 to be transferred to the protuberances 11. Therefore, the thermal printhead 100 makes it possible to raise the temperature of the heater section 41 with low power consumption, and the thermal printhead 100 can be powered by a battery, for example.

[0044] When printing on paper using the thermal printhead 100, a platen roller comes into contact with the heater section 41, with the paper in between. Increasing the pressure from the platen roller increases the amount of deflection of the insulating film 20 below the heater section 41, causing the insulating film 20 below the heater section 41 to come into contact with the bottom surface of the recess 11a. When the insulating film 20 below the heater section 41 comes into contact with the bottom surface of the recess 11a, heat generated in the heater section 41 is transferred to the protrusion 11 via the contact area, facilitating cooling of the heater section 41. As a result, high-speed printing is possible. In this way, the thermal printhead 100 can be switched between an operating state that allows low-power operation and an operating state that allows high-speed printing by adjusting the pressure of the platen roller.

[0045] In the thermal printhead 100, the recess formation step S5 is performed using isotropic dry etching, which allows for the formation of shallow recesses 11a. As a result, when the pressing force of the platen roller is increased, the insulating film 20 below the heater portion 41 and the bottom surface of the recess 11a are more likely to come into contact. When the insulating film 30 is a plasma CVD film, the insulating film 30 tends to grow conformally, so that the insulating film 30 growing around the through hole 21 tends to come into contact with and integrate with each other, making it easier to block the through hole 21. When the opening diameter of the through hole 21 is equal to or smaller than the thickness of the insulating film 30, the insulating film 30 can more reliably block the through hole 21.

[0046] Second Embodiment A thermal printhead according to the second embodiment will be described. The thermal printhead according to the second embodiment will be referred to as thermal printhead 200. Here, differences from thermal printhead 100 will be mainly described, and overlapping descriptions will not be repeated.

[0047] <Configuration of Thermal Printhead 200> The configuration of the thermal printhead 200 will be described below.

[0048] 17 is a cross-sectional view of the thermal printhead 200. As shown in Fig. 17, the thermal printhead 200 has a substrate 10, an insulating film 20, an insulating film 30, a resistor layer 40, a wiring layer 50, and a protective film 60. In this respect, the configuration of the thermal printhead 200 is common to the configuration of the thermal printhead 100.

[0049] In the thermal printhead 200, the protrusion 11 does not have a second side surface in a cross-sectional view perpendicular to the first direction DR1. That is, in the thermal printhead 200, the first side surface is continuous with the top surface at the upper end. In the thermal printhead 200, a recess 11a is formed in the top surface of the protrusion 11. In the thermal printhead 200, the insulating film 30 is made of glass, and is disposed only on the top surface of the protrusion 11 with the insulating film 20 interposed therebetween.

[0050] In the thermal printhead 200, the wiring layer 50 is disposed on the insulating film 30 with the resistor layer 40 interposed therebetween in the portions overlapping the top surfaces of the protrusions 11 in a plan view, but is disposed on the insulating film 20 with the resistor layer 40 interposed therebetween in other portions. In the thermal printhead 200, the protective film 60 is disposed on the insulating film 30 so as to cover the resistor layer 40 and the wiring layer 50 in the portions overlapping the protrusions 11 in a plan view, but is disposed on the insulating film 20 so as to cover the resistor layer 40 and the wiring layer 50 in other portions. In these respects, the configuration of the thermal printhead 200 differs from the configuration of the thermal printhead 100.

[0051] <Method of Manufacturing Thermal Printhead 200> A method of manufacturing the thermal printhead 200 will now be described.

[0052] 18 is a diagram showing the manufacturing process of the thermal printhead 200. As shown in FIG. 18, the manufacturing method of the thermal printhead 200 includes a preparation step S1, a protrusion formation step S2, a first insulating film formation step S3, a through-hole formation step S4, a recess formation step S5, a second insulating film formation step S6, a film deposition step S7, a first etching step S8, a second etching step S9, a third etching step S10, a protective film formation step S11, and a pad formation step S12. In this respect, the manufacturing method of the thermal printhead 200 is common to the manufacturing method of the thermal printhead 100.

[0053] In the manufacturing method of the thermal printhead 200, the protrusion forming step S2 includes a hard mask forming step S21 and a first etching step S22, but does not include a second etching step S23. In the manufacturing method of the thermal printhead 200, in the second insulating film forming step S6, a paste containing glass is applied to the top surfaces of the protrusions 11 with the insulating film 20 interposed therebetween, and the applied paste is fired to form the insulating film 30 made of glass. In these respects, the manufacturing method of the thermal printhead 200 is common to the manufacturing method of the thermal printhead 100.

[0054] <Modification> FIG. 19 is a cross-sectional view of a thermal printhead 200 according to a modification. As shown in FIG. 19, the thermal printhead 200 may have the same insulating film 30 (i.e., the insulating film 30 is a plasma CVD film) as the thermal printhead 100. In this case, the thermal printhead 200 further includes a glaze layer 70. The glaze layer 70 is made of glass. The glaze layer 70 is disposed on the top surface of the protrusion 11 with the insulating films 20 and 30 interposed therebetween. Furthermore, in this case, the wiring layer 50 is disposed on the glaze layer 70 with the resistor layer 40 interposed therebetween in the portion overlapping the top surface of the protrusion 11, and is disposed on the insulating film 30 with the resistor layer 40 interposed therebetween in the other portion. In this case, when the glaze layer 70 is formed, the paste used to form the glaze layer 70 is prevented from passing through the through holes 21 and dropping into the recess 11a.

[0055] <Effects of Thermal Printhead 200> The effects of the thermal printhead 200 will be described below.

[0056] In the thermal printhead 200, a recess 11a is formed on the surface (top surface) of the raised portion 11, and therefore, similar to the thermal printhead 100, when the pressing force from the platen roller is small, it is possible to suppress heat transfer from the heater portion 41 to the raised portion 11, and by increasing the pressing force from the platen roller, it is possible to promote heat transfer from the heater portion 41 to the raised portion 11, thereby enabling high-speed printing.

[0057] Third Embodiment A thermal printing system according to a third embodiment will be described. The thermal printing system according to the third embodiment is referred to as a thermal printing system 300.

[0058] <Configuration of Thermal Printing System 300> The configuration of the thermal printing system 300 will be described below.

[0059] 20 is a schematic diagram of a thermal printing system 300. As shown in FIG. 20, the thermal printing system 300 has a thermal printhead 100, a platen roller 80, a drive mechanism 81, and a controller 82. The platen roller 80 is driven by the drive mechanism 81 and brought into contact with the protective film 60 above the heater unit 41, with paper 83 interposed therebetween. The controller 82 outputs a control signal to the drive mechanism 81 and controls the operation of the drive mechanism 81.

[0060] More specifically, the controller 82 can switch between a first state and a second state the state in which the platen roller 80 presses against the thermal printhead 100. The pressing force of the platen roller 80 against the thermal printhead 100 in the second state is greater than the pressing force of the platen roller 80 against the thermal printhead 100 in the first state.

[0061] Therefore, in the first state, the amount of bending of the insulating film 20 below the heater section 41 is small and the insulating film 20 below the heater section 41 does not come into contact with the bottom surface of the recess 11 a, but in the second state, the amount of bending of the insulating film 20 below the heater section 41 is large and the insulating film 20 below the heater section 41 comes into contact with the bottom surface of the recess 11 a. In this way, the thermal print system 300 can be operated by switching between an operation mode that reduces power consumption and an operation mode that enables high-speed printing.

[0062] In the above example, the thermal printing system 300 is configured using the thermal printhead 100 , but the thermal printing system 300 may also be configured using the thermal printhead 200 instead of the thermal printhead 100 .

[0063] (Additional Notes) The above embodiment includes the following configurations.

[0064] <Supplementary Note 1> A thermal printhead comprising: a substrate; a first insulating film; and a second insulating film, wherein the substrate has a first main surface and a second main surface opposite to the first main surface, a raised portion is formed on the first main surface so as to rise on the side opposite to the second main surface, a recess is formed on a surface of the raised portion, the first insulating film is disposed on the first main surface so as to cover the raised portion, the second insulating film is disposed on the surface with the first insulating film interposed therebetween, and a through hole is formed in a portion of the first insulating film facing a bottom surface of the recess with a gap therebetween.

[0065] <Supplementary Note 2> The thermal printhead according to Supplementary Note 1, wherein the first insulating film has a first layer and a second layer, the first layer is disposed on the first main surface so as to cover the raised portion, and the second layer is disposed on the first layer.

[0066] <Supplementary Note 3> The thermal printhead according to Supplementary Note 2, wherein the first layer is made of a silicon oxide material, and the second layer is made of a silicon nitride material.

[0067] <Supplementary Note 4> The thermal printhead according to any one of Supplementary Note 1 to Supplementary Note 3, wherein the second insulating film is a plasma CVD film.

[0068] <Appendix 5> The thermal printhead according to Appendix 1, wherein the surface is a top surface of the protrusion, the second insulating film is made of glass, and the second insulating film is disposed on the top surface with the first insulating film interposed therebetween.

[0069] <Appendix 6> The thermal printhead of Appendix 1, further comprising a glaze layer, wherein the surface is a top surface of the protrusion, the second insulating film is disposed on the top surface with the first insulating film interposed therebetween, the second insulating film is a plasma CVD film, the constituent material of the glaze layer is glass, and the glaze layer is disposed on the top surface with the first insulating film and the second insulating film interposed therebetween.

[0070] <Supplementary Note 7> The thermal printhead according to any one of Supplementary Note 1 to Supplementary Note 6, wherein the opening diameter of the through hole is equal to or smaller than the thickness of the second insulating film.

[0071] <Appendix 8> The thermal printhead according to appendix 7, wherein the opening diameter is 2 μm or less.

[0072] <Appendix 9> A thermal printhead according to any one of Appendixes 1 to 8, further comprising: a resistor layer; and a wiring layer, wherein the wiring layer is disposed on the second insulating film with the resistor layer interposed therebetween; the raised portion extends along a first direction in a planar view; the wiring layer has a plurality of wiring portions, wherein the plurality of wiring portions are arranged at intervals along the first direction, and each of the plurality of wiring portions extends along a second direction perpendicular to the first direction in a planar view so as to overlap with the raised portion; the resistor layer has a heater portion at a position overlapping with the recess; and each of the plurality of wiring portions is partially removed above the heater portion.

[0073] <Supplementary Note 10> A thermal printing system comprising: the thermal printhead according to Supplementary Note 9; a platen roller; and a controller, wherein the platen roller is pressed against the thermal printhead above the heater unit with paper to be printed therebetween, and the controller is capable of changing a state of pressing the platen roller against the thermal printhead between a first state in which the first insulating film contacts a bottom surface of the recess and a second state in which the first insulating film is spaced apart from the bottom surface of the recess.

[0074] <Supplementary Note 11> A method for manufacturing a thermal printhead, comprising the steps of: preparing a substrate having a first main surface and a second main surface opposite to the first main surface; forming a raised portion on the first main surface that rises on the side opposite the second main surface; forming a first insulating film so as to cover a surface of the raised portion; forming a through hole in a portion of the first insulating film on the surface; forming a recess in the surface by etching via the through hole; and forming a second insulating film on the first main surface with the first insulating film interposed therebetween, wherein the etching is anisotropic dry etching.

[0075] <Supplementary Note 12> The thermal printing system according to Supplementary Note 10, wherein the first state is an operating mode in which the printing speed is faster than that of the second state, and the second state is an operating mode in which power consumption is lower than that of the first state.

[0076] <Appendix 13> The thermal printhead according to any one of Appendices 1 to 9, further comprising a heater section disposed on a portion of the first insulating film that faces a bottom surface of the recess with a gap therebetween, wherein the heat dissipation properties of the heater section change in accordance with deflection of the portion of the first insulating film that faces the bottom surface of the recess with a gap therebetween.

[0077] Although the embodiments of the present disclosure have been described above, the above-described embodiments can be modified in various ways. Furthermore, the scope of the present invention is not limited to the above-described embodiments. The scope of the present invention is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0078] 100, 200 Thermal print head, 300 Thermal print system, 10 Substrate, 10a Main surface, 10b Main surface, 11 Protuberance, 11a Recess, 20 Insulating film, 20a First layer, 20b Second layer, 21 Through hole, 30 Insulating film, 40 Resistor layer, 41 Heater portion, 50 Wiring layer, 51 Wiring portion, 51a, 51b Wiring portion, 52 Connection portion, 60 Protective film, 70 Glaze layer, 80 Platen roller, 81 Drive mechanism, 82 Controller, 83 Paper, DR1 First direction, DR2 Second direction, HM Hard mask, S1 Preparation step, S2 Protuberance formation step, S21 Hard mask formation step, S22 First etching step, S23 Second etching step, S3 First insulating film formation step, S4 Through hole formation step, S5 S6: second insulating film forming step; S7: film forming step; S8: first etching step; S9: second etching step; S10: third etching step; S11: protective film forming step; S12: pad forming step.

Claims

1. A thermal printhead comprising: a substrate, a first insulating film, and a second insulating film, the substrate having a first main surface and a second main surface which is the opposite surface of the first main surface, a raised portion is formed on the first main surface which rises on the side opposite the second main surface, a recess is formed on a surface of the raised portion, the first insulating film is arranged on the first main surface so as to cover the raised portion, the second insulating film is arranged on the surface with the first insulating film interposed therebetween, and a through hole is formed in a portion of the first insulating film which faces a bottom surface of the recess with a gap therebetween.

2. A thermal printhead as described in claim 1, wherein the first insulating film has a first layer and a second layer, the first layer is disposed on the first main surface so as to cover the raised portion, and the second layer is disposed on the first layer.

3. The thermal printhead according to claim 2, wherein the first layer is made of a material selected from the group consisting of silicon oxide and silicon nitride.

4. A thermal printhead according to any one of claims 1 to 3, wherein the second insulating film is a plasma CVD film.

5. A thermal printhead as described in claim 1, wherein the surface is a top surface of the protrusion, the material of the second insulating film is glass, and the second insulating film is disposed on the top surface with the first insulating film interposed therebetween.

6. A thermal printhead as described in claim 1, further comprising a glaze layer, said surface being a top surface of said raised portion, said second insulating film being disposed on said top surface with said first insulating film interposed therebetween, said second insulating film being a plasma CVD film, said glaze layer being made of glass, and said glaze layer being disposed on said top surface with said first insulating film and said second insulating film interposed therebetween.

7. A thermal printhead according to any one of claims 1 to 6, wherein the opening diameter of the through hole is equal to or smaller than the thickness of the second insulating film.

8. The thermal printhead according to claim 7, wherein the opening diameter is 2 μm or less.

9. A thermal printhead as described in any one of claims 1 to 8, further comprising a resistor layer and a wiring layer, the wiring layer being arranged on the second insulating film with the resistor layer interposed therebetween, the raised portion extending along a first direction in a planar view, the wiring layer having a plurality of wiring portions arranged at intervals along the first direction, each of the plurality of wiring portions extending along a second direction perpendicular to the first direction in a planar view so as to overlap with the raised portion, the resistor layer having a heater portion at a position overlapping with the recess, and each of the plurality of wiring portions being partially removed above the heater portion.

10. A thermal printing system comprising the thermal print head of claim 9, a platen roller, and a controller, wherein the platen roller is pressed against the thermal print head above the heater section with paper to be printed interposed therebetween, and the controller is capable of changing the state of pressure of the platen roller against the thermal print head between a first state in which the first insulating film contacts the bottom surface of the recess and a second state in which the first insulating film is spaced apart from the bottom surface of the recess.

11. A method for manufacturing a thermal printhead, comprising the steps of: preparing a substrate having a first main surface and a second main surface that is the opposite surface of the first main surface; forming a raised portion on the first main surface that rises on the side opposite the second main surface; forming a first insulating film so as to cover the surface of the raised portion; forming a through hole in a portion of the first insulating film on the surface; forming a recess in the surface by etching through the through hole; and forming a second insulating film on the first main surface with the first insulating film interposed therebetween, wherein the etching is anisotropic dry etching.

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