Thermal print head and method for manufacturing the same, and thermal printer

Abstract

The present invention provides a thermal print head, which includes: a substrate having a convex portion; a wiring layer on the convex portion; a heat storage layer on the wiring layer; a heating resistor portion formed on the heat storage layer and arranged along a main scanning direction; a first electrode in contact with the heating resistor portion on one side in a sub-scanning direction; a second electrode in contact with the heating resistor portion on the other side in the sub-scanning direction; and a connecting wiring formed in an opening portion that passes through the heating resistor portion and the heat storage layer and reaches the wiring layer, the first electrode being electrically connected to the wiring layer via the connecting wiring.

Description

Technical Field

[0001] The present embodiment relates to a thermal print head, a method for manufacturing the same, and a thermal printer. Background Art

[0002] For example, a thermal print head has a large number of heating parts arranged in the main scanning direction on the head substrate. Each heating part is formed by exposing a part of a resistor layer (also called a heating resistor) formed on the head substrate through a glaze layer (also called a heat storage layer), and stacking a common electrode and a separate electrode in a manner that their ends are opposite to each other. By passing electricity between the common electrode and the separate electrode, the exposed part (heating part) of the resistor layer generates heat due to Joule heat. By transferring the heat to the printing medium (thermal paper for making barcode paper or receipts, etc.), printing on the printing medium is completed.

[0003] For example, in logistics centers, the classification, content details, and order numbers of items are printed on labels, and the use of these labels can simplify and improve the efficiency of inspection work.

[0004] However, in recent years, traceability has become more important, and all information such as the manufacturer's unique mark, manufacturing date, and expiration date are recorded on printed media such as labels and receipts. In addition, the amount of printed information and label printing in the logistics field has tended to increase, such as the mandatory display of nutritional ingredients and changes in allergy indications for food.

[0005] In order to realize the increasing amount of printing, the thermal print head needs to print information on the printing medium at high speed and high precision. In order to print at high speed and high precision, the spacing between the wirings (equal to the spacing between the heating resistors) needs to be narrow. In the wiring formation process of the high-precision thermal print head, in order to further integrate the wirings at a high density, short circuits or disconnections of the wirings occur more frequently, which may lead to a significant reduction in the manufacturing yield.

[0006] When forming a wiring layer such as a common electrode and an individual electrode, a wiring pattern is formed by screen printing a paste using a metal such as gold or silver.

[0007] However, the paste that becomes the wiring pattern contains a solvent (dispersion medium) for dispersing metal particles. There is a possibility that the wiring pattern will be wider than designed due to the solvent, making it difficult to increase the density of the wiring pattern and unable to form a high-precision wiring pattern, which may lead to a significant decrease in manufacturing yield.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Publication No. 2000-141729.

[0011] Patent document 2: Japanese Patent Application Laid-Open No. 5-89716. Summary of the invention

[0012] Technical problem to be solved by the invention

[0013] One method of the present embodiment is to solve at least one of the above problems and is completed in view of the above content, and provides a thermal print head that ensures a good yield. In addition, another method of the present embodiment provides a method for manufacturing the thermal print head. And, another method of the present embodiment provides a thermal printer having the thermal print head.

[0014] Technical solutions to the problem

[0015] In one embodiment of the present invention, a wiring layer is provided on a substrate having a convex portion, and the electrode and the wiring layer are electrically connected via a connecting wiring formed in an opening portion of the wiring layer that penetrates the heat storage layer and the heating resistor portion on the wiring layer. In another embodiment of the present invention, the heat storage layer is formed as a laminated structure of a layer containing glass and a porous layer containing a material different from the layer on the layer, whereby the solvent contained in the paste penetrates into the pores of the porous layer, and diffusion of the wiring pattern can be suppressed. One embodiment of the present invention is as follows.

[0016] One method of the present embodiment is a thermal print head, which includes: a substrate having a convex portion; a wiring layer on the convex portion; a heat storage layer on the wiring layer; a heating resistor portion formed on the heat storage layer and arranged along a main scanning direction; a first electrode in contact with the heating resistor portion on one side in the sub-scanning direction; a second electrode in contact with the heating resistor portion on the other side in the sub-scanning direction; and a connecting wiring formed in an opening portion that passes through the heating resistor portion and the heat storage layer and reaches the wiring layer, and the first electrode is electrically connected to the wiring layer via the connecting wiring.

[0017] Another method of the present embodiment is a thermal print head, which includes: a heat storage layer having a first layer and a second layer on the first layer; wiring formed on the heat storage layer; a heating resistor formed on the wiring; and a protective film covering the heat storage layer, the wiring and the heating resistor, wherein the first layer includes glass and the second layer is a porous layer.

[0018] Another aspect of the present embodiment is a thermal printer including the thermal print head.

[0019] In addition, another method of the present embodiment is a method for manufacturing a thermal print head, forming a wiring film on the surface of a substrate, removing the substrate and a portion of the wiring film to form a convex portion and a wiring layer on the convex portion, forming a heat storage layer on the wiring layer, forming a heating resistor portion arranged along a main scanning direction on the heat storage layer, forming an opening portion that passes through the heating resistor portion and the heat storage layer and reaches the wiring layer, forming a connecting wiring in the opening portion, and forming a first electrode electrically connected to the wiring layer via the connecting wiring, and a second electrode spaced apart from the first electrode in a manner of sandwiching the heating resistor portion along a sub-scanning direction.

[0020] In addition, another method of the present embodiment is a method for manufacturing a thermal print head, wherein a portion of a substrate is removed to form a convex portion, an oxide film is formed on the substrate, a wiring layer is formed on the oxide film, a heat storage layer is formed on the wiring layer, a plurality of heating resistor portions arranged along a main scanning direction are formed on the heat storage layer, an opening portion is formed that passes through the heating resistor portions and the heat storage layer and reaches the wiring layer, a connecting wiring is formed in the opening portion, and a first electrode electrically connected to the wiring layer via the connecting wiring, and a second electrode spaced apart from the first electrode in a manner of sandwiching the heating resistor portion along a sub-scanning direction is formed.

[0021] In addition, another method of the present embodiment is a method for manufacturing a thermal print head, comprising forming a first layer containing glass on a substrate, forming a second layer as a porous layer on the first layer, forming a heat storage layer including the first layer and the second layer, forming wiring on the heat storage layer, forming a heating resistor on the wiring, and forming a protective film covering the heat storage layer, the wiring and the heating resistor.

[0022] Effects of the Invention

[0023] According to the present embodiment, a thermal print head that ensures a good yield can be provided, a method for manufacturing the thermal print head can be provided, and a thermal printer having the thermal print head can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a partially omitted perspective view for explaining a single-chip substrate used in the thermal print head of the first embodiment.

[0025] Figure 2 yes Figure 1 Cross-sectional view of .

[0026] Figure 3 This is a perspective view (part 1) for explaining the method for manufacturing the thermal print head according to the first embodiment.

[0027] Figure 4yes Figure 3 Cross-sectional view of .

[0028] Figure 5 This is a perspective view (part 2) for explaining the method for manufacturing the thermal print head according to the first embodiment.

[0029] Figure 6 yes Figure 5 Cross-sectional view of .

[0030] Figure 7 This is a perspective view (part 3) for explaining the method for manufacturing the thermal print head according to the first embodiment.

[0031] Figure 8 yes Figure 7 Cross-sectional view of .

[0032] Fig. 9 This is a perspective view (part 4) for explaining the method for manufacturing the thermal print head according to the first embodiment.

[0033] Fig.10 yes Fig. 9 Cross-sectional view of .

[0034] Fig.11 This is a perspective view (part 5) for explaining the method for manufacturing the thermal print head according to the first embodiment.

[0035] Fig.12 yes Fig.11 Cross-sectional view of .

[0036] Fig.13 This is a perspective view (part 6) for explaining the method for manufacturing the thermal print head according to the first embodiment.

[0037] Fig.14 yes Fig.13 Cross-sectional view of .

[0038] Fig.15 This is a perspective view (part 7) for explaining the method for manufacturing the thermal print head according to the first embodiment.

[0039] Fig.16 yes Fig.15 Cross-sectional view of .

[0040] Fig.17 This is a perspective view (part eight) for explaining the method for manufacturing the thermal print head according to the first embodiment.

[0041] Fig.18 yes Fig.17 Cross-sectional view of .

[0042] Fig.19 This is a perspective view (part 9) for explaining the method for manufacturing the thermal print head according to the first embodiment.

[0043] Fig. 20 yes Fig.19 Cross-sectional view of .

[0044] Fig.21 This is a perspective view (part 1) for explaining another method of manufacturing the thermal print head according to the first embodiment.

[0045] Fig. 22 yes Fig.21 Cross-sectional view of .

[0046] Fig.23 This is a perspective view (part 2) for explaining another method of manufacturing the thermal print head according to the first embodiment.

[0047] Fig.24 yes Fig.23 Cross-sectional view of .

[0048] Fig.25 This is a perspective view (part 3) for explaining another method of manufacturing the thermal print head according to the first embodiment.

[0049] Fig.26 yes Fig.25 Cross-sectional view of .

[0050] Fig. 27 This is a perspective view (part 4) for explaining another method of manufacturing the thermal print head according to the first embodiment.

[0051] Fig.28 yes Fig. 27 Cross-sectional view of .

[0052] Fig.29 This is a partial perspective view for explaining a single-chip substrate used in a thermal print head according to a second embodiment.

[0053] Fig.30 yes Fig.29 Partial cross-sectional view.

[0054] Fig.31 This is a partial perspective view (part 1) for explaining the method for manufacturing the thermal print head according to the second embodiment.

[0055] Fig.32 yes Fig.31 Partial cross-sectional view.

[0056] Fig.33 This is a partial perspective view (part 2) for explaining the method for manufacturing the thermal print head according to the second embodiment.

[0057] Fig.34 yes Fig.33 Partial cross-sectional view.

[0058] Fig.35 This is a partial perspective view (part 3) for explaining the method for manufacturing the thermal print head according to the second embodiment.

[0059] Fig.36 yes Fig.35 Partial cross-sectional view.

[0060] Fig.37 This is a partial perspective view (part 4) for explaining the method for manufacturing the thermal print head according to the second embodiment.

[0061] Fig.38 yes Fig.37 Partial cross-sectional view.

[0062] Fig.39 is a cross-sectional view illustrating a thermal print head. DETAILED DESCRIPTION

[0063] Next, the present embodiment will be described with reference to the accompanying drawings. In the description of the drawings described below, the same or similar parts are marked with the same or similar reference numerals. However, the drawings are schematic diagrams, and it should be noted that the relationship between the thickness and the plane size of each component may be different from the relationship between the actual thickness and the plane size. Therefore, the specific thickness and size should be determined with reference to the following description. In addition, the drawings of course also include parts with different dimensional relationships or ratios.

[0064] In addition, the embodiments described below are examples of embodiments for embodying the technical concept of a device or method, and do not specify the material, shape, structure, arrangement, etc. of each component. Various modifications can be made to the present embodiment within the scope of the technical claim.

[0065] Specifically, one aspect of this embodiment is as follows.

[0066] <1> A thermal print head, comprising: a substrate having a convex portion; a wiring layer on the convex portion; a heat storage layer on the wiring layer; a heating resistor portion formed on the heat storage layer and arranged along a main scanning direction; a first electrode in contact with the heating resistor portion on one side in a sub-scanning direction; a second electrode in contact with the heating resistor portion on the other side in the sub-scanning direction; and a connecting wiring formed in an opening portion that passes through the heating resistor portion and the heat storage layer and reaches the wiring layer, the first electrode being electrically connected to the wiring layer via the connecting wiring.

[0067] <2> like <1> In the thermal print head described above, the wiring layer contains silicide.

[0068] <3> like <1> In the thermal print head described above, the wiring layer covers the upper surface and side surfaces of the protrusion.

[0069] <4> like <1> In the thermal print head described above, the wiring layer contains metal.

[0070] <5> like <1> ~ <4> In the thermal print head described in any one of the above, the substrate and the protrusion are integrally formed of a single crystal semiconductor.

[0071] <6> like <5> In the thermal print head described above, the single crystal semiconductor is made of silicon.

[0072] <7> like <1> ~ <6> In the thermal print head described in any one of the items, the first electrode is a common electrode, and the second electrode is an individual electrode.

[0073] <8> Such as a thermal printer, which has <1> ~ <7> A thermal print head according to any one of the above.

[0074] <9> A method for manufacturing a thermal print head, wherein a wiring film is formed on a surface of a substrate, the substrate and a portion of the wiring film are removed to form a convex portion and a wiring layer on the convex portion, a heat storage layer is formed on the wiring layer, a heating resistor portion arranged along a main scanning direction is formed on the heat storage layer, an opening portion is formed that passes through the heating resistor portion and the heat storage layer and reaches the wiring layer, a connecting wiring is formed in the opening portion, and a first electrode electrically connected to the wiring layer via the connecting wiring and a second electrode spaced apart from the first electrode in a manner of sandwiching the heating resistor portion along a sub-scanning direction are formed.

[0075] <10> like <9> In the method for manufacturing a thermal print head, the wiring film is formed by silicideing a substrate.

[0076] <11> A method for manufacturing a thermal print head, wherein a portion of a substrate is removed to form a convex portion, an oxide film is formed on the substrate, a wiring layer is formed on the oxide film, a heat storage layer is formed on the wiring layer, a plurality of heating resistors arranged along a main scanning direction are formed on the heat storage layer, an opening is formed that passes through the heating resistors and the heat storage layer and reaches the wiring layer, a connecting wiring is formed in the opening, and a first electrode electrically connected to the wiring layer via the connecting wiring and a second electrode spaced apart from the first electrode in a manner of sandwiching the heating resistors along a sub-scanning direction are formed.

[0077] <12> like <9> ~ <11> The method for manufacturing a thermal print head according to any one of the above, wherein the protrusions are formed by anisotropic etching using potassium hydroxide.

[0078] <13> like <9> ~ <12> The method for manufacturing a thermal print head according to any one of the above, wherein the substrate is composed of a single crystal semiconductor.

[0079] <14> like <13> In the method for manufacturing a thermal print head described above, the single crystal semiconductor is made of silicon.

[0080] <15> like <9> ~ <14> In the method for manufacturing a thermal print head described in any one of the above, the first electrode is a common electrode, and the second electrode is an individual electrode.

[0081] (First Embodiment)

[0082] <Thermal Print Head>

[0083] The thermal print head according to the present embodiment will be described with reference to the drawings.

[0084] Figure 1 and Figure 2 Indicates a substrate that is a part of a thermal print head. In the present embodiment, a single-piece substrate included in the thermal print head is referred to as a single-piece substrate 100. The single-piece substrate 100 includes a substrate 10 having a protrusion 11, a wiring layer 12 on the protrusion 11, an insulating layer 14 on the wiring layer 12, a heat storage layer 16 on the insulating layer 14, a resistor layer 18 on the heat storage layer 16, a first electrode 20a in contact with the resistor layer 18, a second electrode 20b on the resistor layer 18, and a protective film 22 covering the resistor layer 18, the first electrode 20a, and the second electrode 20b. Openings are provided in the heat storage layer 16 and the resistor layer 18, and the opening 19a penetrates the heat storage layer 16 and the resistor layer 18. The first electrode 20a is electrically connected to the wiring layer 12 via a connecting wiring 20c formed in the opening 19a. The resistor layer 18 includes a plurality of heat generating resistors 18a that generate heat by current flowing through the electrodes (the first electrode 20a and the second electrode 20b). The plurality of heat generating resistors 18a are independently formed between the first electrode 20a and the second electrode 20b facing each other. Figure 1 The plurality of heating resistors 18a are omitted. The plurality of heating resistors 18a are arranged in a straight line on the heat storage layer 16 along the main scanning direction Y described later. Figure 1 For easy understanding, the protection film 22 is omitted.

[0085] Figure 1 In the stereoscopic views of FIG. 1 and FIG. 2 , for convenience, there is a case where the substrate 10 corresponding to the single-piece substrate 100 is shown. Figure 2 In the cross-sectional views of FIG. 1 and FIG. 2 , for convenience, there is a case where the cross-sectional views are shown to the outside of the substrate 10 .

[0086] In the present embodiment, the direction in which the plurality of heating resistors 18a extend linearly is defined as the main scanning direction Y, the direction perpendicular to the main scanning direction Y and parallel to the upper surface of the substrate 10 is defined as the sub-scanning direction X, and the direction corresponding to the thickness of the substrate 10 is defined as the thickness direction Z. In other words, the thickness direction Z is a direction perpendicular to each of the main scanning direction Y and the sub-scanning direction X. In addition, in the sub-scanning direction X, the direction in which the first electrode 20a is viewed from the second electrode 20b is defined as the downstream side (downstream direction) of the sub-scanning direction X, and the direction in which the second electrode 20b is viewed from the first electrode 20a is defined as the upstream side (upstream direction) of the sub-scanning direction X.

[0087] The substrate 10 is made of ceramic or single crystal semiconductor. For example, an alumina substrate can be used as a ceramic substrate. For example, a silicon substrate can be used as a single crystal semiconductor substrate. From the viewpoint of easy formation of convex portions, a single crystal semiconductor substrate is preferably used as the substrate 10. From the viewpoint of heat dissipation, an alumina substrate having a relatively high thermal conductivity can also be used as the substrate 10. For example, convex glass can be formed on the alumina substrate to prepare a substrate 10 having convex portions made of glass. An insulating layer can also be formed between the upper surface 10A of the substrate 10 and the wiring layer 12. As the material of the insulating layer, for example, silicon oxide or silicon nitride can be used.

[0088] The ceramic substrate has a rectangular planar shape. The silicon substrate as a semiconductor substrate is also called a silicon wafer and has a substantially circular planar shape. Both the ceramic substrate and the semiconductor substrate are configured in a lattice shape when viewed along the thickness direction Z, which is equivalent to one substrate 10 of the single-chip substrate 100. Therefore, a plurality of single-chip substrates 100 can be manufactured from either one ceramic substrate or one semiconductor substrate.

[0089] The following describes a single-chip substrate 100 manufactured using a silicon substrate. The wiring layer 12 is provided on the top surface 11A of the convex portion 11 in the substrate 10. The wiring layer 12 extends long along the main scanning direction Y. The wiring layer 12 is electrically connected to the first electrode 20a via the connecting wiring 20c, and functions as a common electrode of the single-chip substrate 100. The first electrode 20a electrically connects both ends of the wiring layer 12 in the main scanning direction Y to the external terminal, and a heating voltage is input to the first electrode 20a as a part of the common electrode from the external terminal.

[0090] The wiring layer 12 can be formed using a compound obtained by heat-treating the substrate 10 and the conductive layer provided on the substrate 10 so that the material of the substrate 10 and the material of the conductive layer react. Examples of the conductive layer include titanium, nickel, cobalt, sodium, magnesium, platinum, tungsten, molybdenum, tantalum, vanadium, zirconium, hafnium, etc. As the wiring layer 12, for example, a low-resistance conductive layer can be used by forming titanium on a silicon substrate and heat-treating it so that the surface of the silicon substrate reacts with titanium (silicide).

[0091] The insulating layer 14 is formed on the wiring layer 12 using a high-resistance material as a base of the heat storage layer 16. The insulating layer 14 is made of an insulating material, such as silicon oxide or silicon nitride. The dimension of the insulating layer 14 in the thickness direction Z (the thickness of the insulating layer 14) is not particularly limited, and for example, it is 5 μm to 15 μm, preferably 5 μm to 10 μm.

[0092] The heat storage layer 16 is formed on the insulating layer 14 and is sometimes referred to as a glaze layer. The heat storage layer 16 extends long along the main scanning direction Y. The heat storage layer 16 stores heat generated from the heating resistor 18a described later. The heat storage layer 16 can be made of an insulating material, for example, silicon oxide or silicon nitride, which is a main component of glass. The size of the heat storage layer 16 in the thickness direction Z is not particularly limited, and is, for example, 30 to 80 μm, preferably 40 to 60 μm.

[0093] An insulating layer 17 is formed in the substrate 10 of the present embodiment. The insulating layer 17 is formed on the heat storage layer 16 and on the upper surface 10A of the substrate 10. The insulating layer 17 is made of an insulating material, for example, a silicon oxide layer or a silicon nitride layer can be used. As the silicon oxide layer, for example, silicon oxide formed using TEOS (tetraethyl orthosilicate) as a raw material can be used. Viewed along the main scanning direction Y, the resistor layer 18, the first electrode 20a, and the second electrode 20b described later are formed on the insulating layer 17, respectively. Viewed along the main scanning direction Y, the insulating layer 17 is formed between the upper surface of the heat storage layer 16 and the resistor layer 18 including the heating resistor portion 18a. There is also a case where the insulating layer 17 is formed between the upper surface of the heat storage layer 16 and the first electrode 20a and the second electrode 20b.

[0094] In the resistor layer 18, the portion through which the current from the first electrode 20a and the second electrode 20b flows generates heat. Specifically, the resistor layer 18 to which a heating voltage is independently applied according to a printing signal sent from the outside to the driver IC generates heat selectively. Printing dots are formed by heat generation in this way. The resistor layer 18 uses a material having a higher resistivity than the material constituting the first electrode 20a and the second electrode 20b. For example, tantalum nitride or silicon oxide containing tantalum can be used. Ruthenium oxide can also be used as the material of the resistor layer 18. In the present embodiment, the dimension of the resistor layer 18 in the thickness direction Z is, for example, about 0.05 to 0.2 μm. One heating resistor portion 18a in the resistor layer 18 corresponds to one printing dot.

[0095] The first electrode 20a is formed on one side (downstream side) in the sub-scanning direction and functions as a part of the common electrode. In the opening 19a provided in a manner penetrating the heat storage layer 16, the insulating layer 17 and the resistor layer 18, a connecting wiring 20c is formed with the same material as the first electrode 20a. The first electrode 20a is electrically connected to the wiring layer 12 via the connecting wiring 20c. That is, the first electrode 20a, the connecting wiring 20c and the wiring layer 12 have the function of a common electrode. In addition, in the present embodiment, the positions of the two ends of the first electrode 20a are higher than the top surface 11A of the convex portion 11, but are not limited to this. For example, the first electrode 20a may also overlap with the side surface 11B of the convex portion 11 and the upper surface 10A of the substrate 10. The second electrode 20b is formed on the other side (upstream side) in the sub-scanning direction and functions as a single electrode. The first electrode 20a and the second electrode 20b constitute a path for conducting electricity with the resistor layer 18. Specifically, current sequentially flows from the wiring layer 12 functioning as a common electrode, the connection wiring 20 c , and the first electrode 20 a to the second electrode 20 b functioning as an individual electrode via the resistor layer 18 .

[0096] The above-mentioned openings 19a are provided in plurality, and these openings 19a are also referred to as downstream openings. In addition, a plurality of openings 19b are provided in a through manner in the heat storage layer 16, the insulating layer 17 and the resistor layer 18, and these openings 19b are also referred to as upstream openings. The plurality of openings 19a are arranged near the end portion on the downstream side of the convex portion 11 in a ratio of one to the plurality of heating resistor portions 18a. The plurality of openings 19a may also be arranged regularly. In the single-chip substrate 100, there is a situation where a voltage drop in the central portion of the plurality of heating resistor portions 18a arranged along the main scanning direction Y becomes a problem. In this case, it is preferred to arrange the plurality of openings 19a sparsely near the two end portions along the main scanning direction Y, and the closer to the central portion, the denser the arrangement.

[0097] At least one opening 19b is disposed at one end and the other end along the main scanning direction Y near the end on the upstream side of the convex portion 11. The plurality of openings 19b are disposed so as to overlap with the wiring layer 12 as viewed along the thickness direction Z. Preferably, the same number of openings 19b are disposed at one end and the other end along the main scanning direction Y.

[0098] As the first electrode 20a, the second electrode 20b and the connecting wiring 20c, for example, a metal layer of aluminum, copper, titanium, gold, etc. can be used. In addition, the first electrode 20a, the second electrode 20b and the connecting wiring 20c may also have a multilayer structure, for example, a stacked structure of a titanium layer mainly composed of titanium and a copper layer mainly composed of copper formed on the titanium layer. In addition, the dimensions of the first electrode 20a, the second electrode 20b and the connecting wiring 20c in the thickness direction Z are, for example, about 0.2 to 0.8 μm.

[0099] The first electrode 20a (common electrode) is a portion that is electrically opposite to the second electrodes 20b (individual electrodes) when a printer equipped with a thermal print head is used. The common electrode has a first electrode 20a as a plurality of comb-tooth portions and a wiring layer 12 as a common portion that connects these plurality of comb-tooth portions in common. The wiring layer 12 as the common portion is formed on the protrusion 11 of the substrate 10 in the main scanning direction Y, and each comb-tooth portion is formed in a strip shape extending in the sub-scanning direction X on the insulating layer 17 formed on the heat storage layer 16. When viewed along the thickness direction Z, the front end of the upstream side of each comb-tooth portion is opposite to the front end of each second electrode 20b at a predetermined interval on the downstream side along the sub-scanning direction X.

[0100] At both ends of the single-piece substrate 100 in the main scanning direction Y as viewed along the thickness direction Z, upstream connection wiring 20d is formed on the insulating layer 17 formed on the heat storage layer 16. The wiring layer 12 formed below the heat storage layer 16 is electrically connected to the connection wiring 20d formed on the heat storage layer 16 through the connection wiring 20c at both ends of the single-piece substrate 100 in the main scanning direction Y as viewed along the thickness direction Z. The connection wiring 20d extends upstream ( Figure 1 The connection wiring 20d is exposed from the protective film 22 on the upstream side in the sub-scanning direction X. The portion of the connection wiring 20d exposed from the protective film 22 constitutes a heating pad portion 20d1 to which a heating voltage is supplied. A heating voltage is applied to each heating resistor portion 18a as needed.

[0101] Each second electrode 20b is formed in a strip shape extending substantially in the secondary scanning direction X, and they are not electrically connected to each other. Therefore, when using a printer equipped with a thermal print head, different potentials can be independently given to each second electrode 20b. An individual pad portion 20b1 is formed at the end of each second electrode 20b. The individual pad portion 20b1 and the heat generating pad portion 20d1 are exposed from the protective film 22 on the upstream side of the secondary scanning direction X. Figure 1 (and later references Fig.17 and Fig.19 ) and the end of the wiring layer 12 along the main scanning direction Y are both located inside the end of the substrate 10 at a certain distance (for example, 0.5 mm).

[0102] In the prior art, the strip-shaped electrode extending in the secondary scanning direction X has two adjacent parts including a folded shape. The two adjacent parts are respectively connected to two adjacent heating resistor parts. These two adjacent heating resistor parts constitute one printing dot. The center interval (dot spacing) of the formed printing dot becomes the center interval between the two adjacent heating resistor parts and the two adjacent heating resistor parts. Therefore, it is difficult to reduce the center interval to form a high-precision electrode pattern, and it is impossible to perform high-precision printing on the printing medium.

[0103] However, in the thermal print head 200 (see Fig.39 ), the common electrode is formed by the first electrode 20a and the wiring layer 12, and the individual electrode is formed by the second electrode 20b. Viewed along the thickness direction Z, a portion of the common electrode overlaps with the individual electrode via the heat storage layer 16 in the thickness direction Z, so the electrode does not need to be formed in a folded shape, and high integration of the common electrode and the individual electrode can be achieved. Moreover, the center spacing (electrode spacing) of adjacent electrodes is equal to the dot spacing. Thus, the electrode spacing can be reduced to form a high-precision electrode pattern, and high-precision printing can be performed on the printed medium. The dot spacing can be formed to be, for example, less than 63.5μm, and can further be formed to be less than 42.3μm.

[0104] The protective film 22 covers the first electrode 20a and the second electrode 20b, etc., and protects the first electrode 20a and the second electrode 20b, etc. from wear, corrosion, oxidation, etc. The protective film 22 can be made of an insulating material, such as silicon nitride, silicon oxide, etc. The dimension of the protective film 22 in the thickness direction Z is, for example, about 3 to 8 μm. The individual pad portion 20b1 and the heat-generating pad portion 20d1 on the upstream side of the secondary scanning direction X are exposed from the protective film 22.

[0105] Here, the thermal print head 200 (see Fig.39). In the figures showing the manufacturing method, for convenience, there is a case where the substrate 10 corresponding to the single-piece substrate 100 is shown. In fact, each process is performed on a plurality of regions corresponding to a plurality of substrates 10, with one ceramic substrate and one semiconductor substrate respectively included as the object.

[0106] like Figure 3 and Figure 4 As shown, first, a semiconductor substrate (for example, a silicon substrate) including a plurality of substrates 10a is prepared. Next, a conductive film 12a serving as a wiring layer 12 is formed on the substrate 10a, and then an insulating film 14a serving as an insulating layer 14 is formed on the conductive film 12a. The substrate 10a, the conductive film 12a, and the insulating film 14a can use the materials exemplified in the above-mentioned substrate 10, wiring layer 12, and insulating layer 14, respectively. For example, titanium or the like can be used for the conductive film 12a. For example, silicon oxide or the like can be used for the insulating film 14a.

[0107] Then, if Figure 5 and Figure 6 As shown, a resist pattern 15 is formed on the insulating film 14a.

[0108] Then, if Figure 7 and Figure 8 As shown, using the resist pattern 15 as a mask, a part of the conductive film 12a and a part of the insulating film 14a are removed to form the wiring layer 12 and the insulating layer 14. Then, the resist pattern 15 is peeled off. This peeling can be performed using, for example, hydrofluoric acid.

[0109] Then, if Fig. 9 and Fig.10 As shown, a portion of the substrate 10a is removed using the wiring layer 12 and the insulating layer 14 as a mask to form a substrate 10 having a convex portion 11. For example, a portion of the substrate 10a can be removed by anisotropic etching using potassium hydroxide. Through this process, a convex portion 11 having a trapezoidal cross-sectional shape is formed when viewed along the main scanning direction Y. The convex portion 11 has a top surface 11A composed of a plane parallel to the upper surface of the substrate 10. On the top surface 11A, the wiring layer 12 and the insulating layer 14 are formed in sequence from the bottom. Depending on the situation, an insulating layer (not shown) is formed between the top surface 11A and the wiring layer 12. In this case, first, before the formation of the conductive film 12a, a portion of the substrate 10a is removed to form the substrate 10 having the convex portion 11, and then an insulating layer, a wiring layer 12 and an insulating layer 14 are formed on the substrate 10 having the convex portion 11. The insulating layer may be provided only on the top surface 11A, may be provided on the top surface 11A and the side surface 11B of the protrusion 11 , or may be provided on the entire upper surface 10A of the substrate 10 .

[0110] Then, if Fig.11 and Fig.12 As shown, the heat storage layer 16 is formed on the insulating layer 14. The heat storage layer 16 can be formed by, for example, dispensing a glass paste from a dispenser and then performing a firing process. The firing process is performed at, for example, 850 to 1200° C. for 1 to 5 hours.

[0111] Then, if Fig.13 and Fig.14 As shown, an insulating layer 17 and a resistor layer 18 are formed on the substrate 10 and the heat storage layer 16. The insulating layer 17 can be made of, for example, silicon oxide formed by CVD using TEOS (tetraethyl orthosilicate) as a raw material. The resistor layer 18 can be made of, for example, tantalum nitride formed by sputtering.

[0112] Then, if Fig.15 and Fig.16 As shown in FIG. 1 , openings 19a and 19b are formed in the insulating layer 14, the heat storage layer 16, and the resistor layer 18. The openings 19a and 19b are formed so that a portion of the upper surface of the wiring layer 12 is exposed. Fig.15 As shown in FIG. 1 , the opening 19a and the opening 19b are arranged to be staggered when viewed along the sub-scanning direction X. Fig.16 The middle opening 19b is not shown. The opening 19b is located at the following position in the sub-scanning direction X. This position is located at the position where the center line of the top surface 11A of the convex portion 11 is sandwiched. Fig.16 The openings 19 a shown are located at line-symmetrical positions and extend along the main scanning direction Y toward both ends of the substrate 10 .

[0113] Then, if Fig.17 and Fig.18 As shown, for example, a connection wiring 20c is formed in the opening 19a by photolithography, and the first electrode 20a electrically connected to the wiring layer 12 via the connection wiring 20c. The connection wiring 20c may be formed on the inner wall surface of the opening 19a, or may be formed in a manner that fills the inside of the opening 19a. In the same process, the second electrode 20b is formed, which is opposite to the front end of the first electrode 20a at a predetermined interval along the secondary scanning direction X, the connection wiring 20c in the opening 19b, and the connection wiring 20d electrically connected to the wiring layer 12 via the connection wiring 20c. The resistor layer 18 is exposed from the first electrode 20a and the second electrode 20b between the front ends of the first electrode 20a and the second electrode 20b as viewed along the thickness direction Z. After the process is completed, the wiring layer 12 formed under the insulating layer 14 is formed below the heat storage layer 16. In addition, the first electrode 20a and the second electrode 20b are formed above the heat storage layer 16. Therefore, the wiring layer 12 corresponds to the lower wiring, and the first electrode 20 a and the second electrode 20 b correspond to the upper wiring.

[0114] The first electrode 20a functions as a part of the common electrode, and the second electrode 20b functions as a separate electrode. Viewed along the thickness direction Z, the wiring layer 12 (lower wiring) as a part of the common electrode overlaps with the second electrode 20b (upper wiring) as a separate electrode. Therefore, the common electrode and the separate electrode do not need to be formed into a folded shape, and high integration of the common electrode (first electrode 20a) and the separate electrode (second electrode 20b) can be achieved. As a result, the electrode spacing can be reduced to form a high-precision electrode pattern, and high-precision printing can be performed on the printing medium.

[0115] In addition, in the thermal print head 200 (see Fig.39 ), when viewed along the main scanning direction Y, the midpoint between the front end of the first electrode 20a and the front end of the second electrode 20b is located on the downstream side (first electrode 20a side) of the central part of the heat storage layer 16 in the sub-scanning direction X. That is, the area of ​​the resistor layer 18 that does not overlap with the first electrode 20a and the second electrode 20b (the area where the upper surface of the resistor layer 18 is exposed from each electrode) is located on the downstream side of the central part of the heat storage layer 16 in the sub-scanning direction X. With such a structure, when printing on the print medium, the print medium can be smoothly transported to the downstream side of the sub-scanning direction X, so that the print medium can be printed at a higher speed and with higher precision. The present invention is not limited to the above structure, and the position of the area of ​​the resistor layer 18 that does not overlap with the first electrode 20a and the second electrode 20b can also be the central part of the heat storage layer 16 when viewed along the main scanning direction Y.

[0116] Then, if Fig.19 and Fig. 20 As shown in FIG. 2 , a protective film 22 is formed. For example, silicon nitride or the like formed by CVD can be used for the protective film 22 .

[0117] Next, the semiconductor substrate is cut using a dicing machine, for example, to produce a single-piece substrate 100 as a single substrate. Cutting is performed along the main scanning direction Y and the sub-scanning direction X. The position where the semiconductor substrate is cut along the main scanning direction Y is preferably aligned with the position of the substrate. Fig. 20 The protective film 22 shown is slightly on the downstream side compared to the point where the downstream side becomes flat.

[0118] Then, if Fig.39 As shown, the single-piece substrate 100 is fixed to the heat sink 8 using an adhesive (not shown) or the like. The connection substrate 5 on which the driver IC 7 and the connector 59 are mounted is fixed to the heat sink 8 using screws (not shown) or the like.

[0119] Next, wiring is connected around the driver IC 7. The pads for inputting and outputting with the outside of the driver IC 7 are electrically connected to the pads of the connection substrate 5 by wires. The pads for the heating resistor 18a and the individual pad 20b1 (see FIG. 1 ) are electrically connected to the pads of the driver IC 7 by wires. Figure 1 ) are electrically connected. The heat generating pad portion 20d1 (see Figure 1 ) and the heating pads of the connection substrate 5. The above-mentioned pads and wires are electrically connected. Fig.39 There is no indication in .

[0120] Next, a sealing resin (not shown) is formed on the upper surface of the single-chip substrate 100 and the upper surface of the connection substrate 5 so as to include the connection portions between each pad and each wire, each wire, and the driver IC 7. As the sealing resin, a thermosetting resin such as epoxy resin can be used. Through the above steps, the thermal print head 200 of this embodiment can be manufactured.

[0121] In addition, as another structure of the single-chip substrate of the thermal print head of the present embodiment, a structure in which a wiring layer covers the upper surface and the side surfaces of the protrusions of the substrate 10 may be adopted. A method for manufacturing the wiring layer will be described.

[0122] like Fig.21 and Fig. 22 As shown, a substrate 10 having protrusions 11 is prepared. The substrate 10 having protrusions 11 can be obtained by, for example, forming a resist pattern on the above-mentioned substrate 10a and removing a part of the substrate 10a by anisotropic etching using potassium hydroxide using the resist pattern as a mask.

[0123] Then, if Fig.23 and Fig.24 As shown in FIG. 1 , an insulating film 24 is formed on the substrate 10. The insulating film 24 can be formed by the materials and the formation method exemplified in the above-mentioned insulating film 14a.

[0124] Then, if Fig.25 and Fig.26 As shown in FIG. 1 , a conductive film 26a is formed on the insulating film 24. The conductive film 26a can be made of, for example, titanium, nickel, cobalt, sodium, magnesium, platinum, tungsten, molybdenum, tantalum, vanadium, zirconium, hafnium, or the like, which is sputtered.

[0125] Then, if Fig. 27 and Fig.28 As shown, a part of the conductive film 26a is removed to form the wiring layer 26 that covers the top surface 11A and the side surface 11B of the protrusion 11 of the substrate 10. This removal can be performed by photolithography, for example.

[0126] The subsequent steps of forming the heat storage layer, resistor layer, common electrode, individual electrode, protective film, etc. can adopt the above-mentioned steps (using Figures 11 to 20 process described).

[0127] In the structure in which the wiring layer 26 covers the upper surface and the side surface of the protrusion 11 of the substrate 10, the wiring layer 26 and the first electrode 20a function as a common electrode. In addition, the first electrode 20a may be in contact with the wiring layer 26 via an opening provided in a manner penetrating the insulating layer 14, the heat storage layer 16, and the resistor layer 18 as described above. In addition, an opening may be provided in a region in the resistor layer 18 that contacts the side surface of the protrusion 11 of the substrate 10, and the first electrode 20a may be in contact with the wiring layer 26 via the opening.

[0128] According to this embodiment, since the wiring layer 12 (or wiring layer 26) as a part of the common electrode overlaps with the second electrode 20b as the individual electrode when viewed along the thickness direction Z, high integration of the common electrode and the individual electrode can be achieved. As a result, the electrode spacing can be reduced to form a high-precision electrode pattern, a good yield can be ensured, and high-precision printing can be performed on the printing medium.

[0129] (Second Embodiment)

[0130] <Thermal Print Head>

[0131] The thermal print head according to the present embodiment will be described with reference to the drawings.

[0132] Fig.29 and Fig.30 Indicates a substrate that is a part of a thermal print head. In the present embodiment, a single-piece substrate included in the thermal print head is referred to as a single-piece substrate 100A. The single-piece substrate 100A includes: a substrate 115; a heat storage layer 133 extending linearly on the substrate 115; an individual electrode 131 and a common electrode 132 on the heat storage layer 133; a heating resistor 140 on the individual electrode 131, on the common electrode 132, and on the heat storage layer 133; and a protective film 134 on the individual electrode 131, on the common electrode 132, on the heat storage layer 133, and on the heating resistor 140. The heat storage layer 133 includes a first layer 133a and a second layer 133b on the first layer 133a, the first layer 133a includes glass, and the second layer 133b is a porous layer including a material different from the first layer 133a. In addition, the individual electrode 131 and the common electrode 132 are collectively referred to as wiring. The heating resistor 140 includes a plurality of heating resistor portions 141 that generate heat by a current flowing through the wiring (the individual electrodes 131 and the common electrode 132 ). The plurality of heating resistor portions 141 are arranged linearly on the heat storage layer 133 .

[0133] In the present embodiment, the direction in which the plurality of heating resistors 141 extend linearly is defined as the main scanning direction Y, the direction perpendicular to the main scanning direction Y and parallel to the upper surface of the substrate 115 is defined as the sub-scanning direction X, and the direction corresponding to the thickness of the substrate 115 is defined as the thickness direction Z. In other words, the thickness direction Z is a direction perpendicular to each of the main scanning direction Y and the sub-scanning direction X.

[0134] The substrate 115 is made of ceramic or single crystal semiconductor. As a ceramic substrate, for example, an alumina substrate can be used. As a single crystal semiconductor substrate, for example, a silicon substrate can be used. From the perspective of heat dissipation, an alumina substrate having a relatively high thermal conductivity is preferably used for the substrate 115.

[0135] On the substrate 115 composed of an alumina substrate or the like, a heat storage layer 133 (also referred to as a glaze layer) having a function of storing heat is stacked. The heat storage layer 133 stores heat generated by the heating resistor 141 described later. The heat storage layer 133 can be made of an insulating material, for example, silicon oxide or silicon nitride, which is a main component of glass. The dimension of the heat storage layer 133 in the thickness direction Z is not particularly limited, and is, for example, 30 to 80 μm, preferably 40 to 60 μm.

[0136] The heat storage layer 133 of this embodiment is composed of a first layer 133a and a second layer 133b. The first layer 133a is a non-porous layer containing glass. The dimension of the first layer 133a in the thickness direction Z is 20 to 60 μm, preferably 30 to 50 μm, from the viewpoint of pressure resistance.

[0137] The second layer 133b is a porous layer containing a material different from that of the first layer 133a. For example, the second layer 133b may contain porous glass as a glass material different from that of the first layer 133a. The porous glass may also be porous glass (Shirasu Porous Glass) which is a CaO-Al2O3-B2O3-SiO2 type glass. A large number of holes are provided on the surface of the second layer 133b, and the solvent contained in the metal paste used in the formation of the individual electrode 131 and the common electrode 132 described later penetrates into the holes on the surface of the second layer 133b. By this penetration, the diffusion of the wiring patterns of the individual electrode 131 and the common electrode 132 can be suppressed. The porosity of the second layer 133b is not particularly limited, and can be appropriately adjusted in accordance with the physical properties of the paste provided on the second layer 133b.

[0138] The dimension of the second layer 133 b in the thickness direction Z is 10 to 30 μm, preferably 10 to 20 μm.

[0139] The second layer 133b is a porous layer, and its pressure resistance is inferior to that of the first layer 133a. Therefore, by using the thermal storage layer 133 having a stacked structure of the first layer 133a and the second layer 133b, the pressure resistance can be ensured by the action of the first layer 133a, and a high-precision wiring pattern can be formed by the action of the second layer 133b. For example, by making the film thickness of the second layer 133b smaller than that of the first layer 133a, or making the viscosity of the first layer 133a higher than that of the second layer 133b, pressure resistance can be ensured, and a high-precision wiring pattern can be formed.

[0140] Wiring (individual electrodes 131 and common electrodes 132) formed of metal paste is provided on the heat storage layer 133. The common electrode 132 has a comb-tooth portion 132A and a common portion 132B. The individual electrode 131 has a wide portion and a narrow portion. The comb-tooth portion 132A of the common electrode 132 may also have a wide portion and a narrow portion.

[0141] The wiring is obtained by applying a metal paste using a screen printing method or the like to form a wiring pattern. Since the metal paste as the raw material of the wiring is applied on the second layer 133b as a porous layer, the solvent contained in the metal paste penetrates into the pores of the second layer 133b. This penetration can inhibit the metal paste from wetting and diffusing on the second layer 133b. Specifically, the actual wiring width can be made less than 1.5 times the design value of the wiring width. By setting the viscosity of the glass paste used as the material of the second layer 133b, the porosity of the second layer 133b, etc. to appropriate values, the wiring width can be made less than 1.2 times the design value of the wiring width. By making the ratio of the wiring width to the design value of the wiring width close to 1, a higher and finer wiring pattern can be formed. For example, the wiring width of the wiring (individual electrode 131 and common electrode 132 (comb tooth portion 132A)) can be made greater than 20 μm and less than 50 μm. The interval between adjacent wirings (the interval between the outer edges of the wide width portions of adjacent wirings (the size of the gap)) can be set to 10 μm or more and 50 μm or less. The center-to-center interval between adjacent wirings (wiring pitch) can be set to more than 40 μm and 70 μm or less.

[0142] As the metal paste, for example, a paste containing metal particles such as copper, silver, palladium, iridium, platinum and gold can be used. From the viewpoint of the properties and ionization tendency of the metal, copper, silver, platinum and gold are preferred, and from the viewpoint of the properties, ionization tendency and cost reduction of the metal, copper and silver are more preferred. In addition, the solvent contained in the metal paste has the function of uniformly dispersing the metal particles, and examples thereof include ester solvents, ketone solvents, glycol ether solvents, aliphatic solvents, alicyclic solvents, aromatic solvents, alcohol solvents, water, etc., or a mixture of two or more thereof, but are not limited thereto.

[0143] Examples of the ester solvent include ethyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, amyl acetate, ethyl lactate, dimethyl carbonate, etc. Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone benzene, diisobutyl ketone, diacetone alcohol, isophorone, cyclohexanone, etc. Examples of the glycol ether solvent include ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, etc., acetates of these monoethers, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, etc., or acetates of these monoethers.

[0144] Examples of aliphatic solvents include n-heptane, n-hexane, cyclohexane, methylcyclohexane, ethylcyclohexane, etc. Examples of alicyclic solvents include methylcyclohexane, ethylcyclohexane, cyclohexane, etc. Examples of aromatic solvents include toluene, xylene, tetralin, etc. Examples of alcohol solvents (except the above-mentioned glycol ether solvents) include ethanol, propanol, butanol, etc.

[0145] The metal paste may contain a dispersant, a surface treatment agent, an abrasion resistance enhancer, an infrared absorber, an ultraviolet absorber, a fragrance, an antioxidant, an organic pigment, an inorganic pigment, a defoaming agent, a silane coupling agent, a titanate coupling agent, a plasticizer, a flame retardant, a moisturizer, an ion capture agent, etc. as needed.

[0146] Each individual electrode 131 is formed in a strip shape extending substantially in the sub-scanning direction X, and is not electrically connected to each other. Therefore, when a printer equipped with a thermal print head is used, different potentials can be independently applied to each individual electrode 131. An individual pad portion is formed at the end of each individual electrode 131.

[0147] The common electrode 132 is a portion of electrically opposite polarity to the plurality of individual electrodes 131 when a printer equipped with a thermal print head is used. The common electrode 132 has a plurality of comb-tooth portions 132A and a common portion 132B that connects the plurality of comb-tooth portions 132A together. The common portion is formed along the edge of the upper side of the substrate 115 in the main scanning direction Y. Each comb-tooth portion branches from the common portion to form a strip extending in the sub-scanning direction X. The front end portion of each comb-tooth portion enters between the front ends of two adjacent individual electrodes 131, and faces the two individual electrodes 131 at a predetermined interval along the main scanning direction Y.

[0148] The front end of each comb-tooth portion may be opposed to the front end of each individual electrode 131 at a predetermined interval along the secondary scanning direction X. In this case, it is preferred that the heating resistor portion 141 be formed only in the region where the front end of the comb-tooth portion faces the front end of the individual electrode 131. In other words, it is preferred that the heating resistor portion 141 be not disposed except in the region where the front end of the comb-tooth portion faces the front end of the individual electrode 131 in the primary scanning direction Y.

[0149] In the heating resistor portion 141, the portion where the current from the wiring (the individual electrode 131 and the common electrode 132) flows generates heat. Specifically, the heating resistor portion 141, to which a printing signal sent from the outside such as a driver IC is input, is independently energized according to the printing signal, thereby selectively generating heat. In this way, printing dots are formed by heat generation. The heating resistor portion 141 uses a material having a higher resistivity than the material constituting the wiring, for example, tantalum nitride or silicon oxide containing tantalum can be used. Ruthenium oxide can also be used as the material of the heating resistor portion 141. In the present embodiment, the dimension of the heating resistor portion 141 in the thickness direction Z is, for example, about 0.05 to 0.2 μm.

[0150] The wiring and the heating resistor 141 are covered by the protective film 134 to protect the wiring and the heating resistor 141 from wear, corrosion, oxidation, etc. The protective film 134 can be made of an insulating material, such as silicon nitride, silicon oxide, etc. The dimension of the protective film 134 in the thickness direction Z is, for example, about 3 to 8 μm.

[0151] Here, a method for manufacturing the single-piece substrate 100A according to the present embodiment will be described.

[0152] like Fig.31 and Fig.32 As shown, first, a substrate 115 is prepared, a first glass paste (equivalent to the first layer 133a before firing) is applied on the substrate 115 by screen printing or the like, the applied first glass paste is dried, and a first layer 133a, which is a part of the heat storage layer 133, can be formed on the substrate 115 by a firing process described later. The viscosity of the first layer 133a before firing is 50 cP or more and 200 cP or less.

[0153] Then, if Fig.33 and Fig.34As shown, on the dried first glass paste, the second glass paste (equivalent to the second layer 133b before firing) is applied by screen printing or the like, and the applied paste-like porous material is dried. Thereafter, the dried first glass paste and the second glass paste are fired and heat-treated to form a heat storage layer 133 including the first layer 133a and the second layer 133b on the substrate 115. In the present embodiment, the second glass paste is fired and heat-treated to form porous glass (porous glass) from phase-separated glass. Air is contained in the interconnecting pores of the porous glass. Porous glass is a material containing air. The firing process is performed, for example, at 1250°C for 4.5 hours. The viscosity of the second layer 133b before firing is greater than 50 cP and less than 200 cP.

[0154] Then, if Fig.35 and Fig.36 As shown, a separate electrode 131 and a common electrode 132 are formed on the heat storage layer 133. The common electrode 132 has a comb-tooth portion 132A and a common portion 132B. The separate electrode 131 and the common electrode 132 can be obtained by applying the above-mentioned metal paste by screen printing or the like and forming a wiring pattern. Since the heat storage layer 133 of this embodiment includes a second layer 133b as a porous layer, the solvent contained in the metal paste penetrates into the pores of the second layer 133b. By this penetration, it is possible to suppress the metal paste from infiltrating and diffusing on the second layer 133b, and it is possible to directly form the wiring patterns of the separate electrodes 131 and the common electrode 132 on the heat storage layer 133 without going through a wiring pattern forming process based on photolithography or the like. As a result, the process of forming the wiring patterns of the separate electrodes 131 and the common electrode 132 can be simplified, and a more high-precision wiring pattern can be formed.

[0155] Then, if Fig.37 and Fig.38 As shown, the heating resistor 140 (heating resistor portion 141) is formed by thick film forming technology. The heating resistor 140 (heating resistor portion 141) is formed by firing a resistor paste supplied by screen printing or a dispenser. The resistor paste contains, for example, ruthenium oxide.

[0156] And, if Fig.30 As shown, the protective film 134 is formed by thin film forming technology. For example, silicon nitride using CVD can be used for the protective film 134. The protective film 134 can also be formed by thick film forming technology. In this case, the protective film 134 made of glass is formed by firing the screen-printed glass paste.

[0157] Through the above steps, the thermal print head of this embodiment can be manufactured.

[0158] According to this embodiment, by having the second layer 133b as a porous layer, a high-definition wiring pattern can be obtained. In addition, by having the thermal storage layer 133 stacked with the first layer 133a and the second layer 133b, not only a high-definition wiring pattern can be obtained but also the pressure resistance of the thermal storage layer 133 can be ensured.

[0159] <Thermal Printer>

[0160] About the use of thermal print head 200 Fig.39 . In addition, here, the thermal print head 200 is described as having a structure of the single-chip substrate 100 described in the first embodiment. The thermal print head 200 has a substrate 10 (the wiring layer 12 and the heat storage layer 16 on the substrate 10 are not shown), a connecting substrate 5 and a heat dissipation component 8. The substrate 10 and the connecting substrate 5 are mounted on the heat dissipation component 8 adjacent to each other in the sub-scanning direction X. A plurality of heating resistor portions 18a arranged in the main scanning direction Y are formed on the substrate 10. The heating resistor portion 18a is driven in a selectively heating manner by a driving IC 7 mounted on the connecting substrate 5. The heating resistor portion 18a prints on a printing medium 92 such as thermal paper pressed on the heating resistor portion 18a by a paper pressing roller 91 according to a printing signal sent from the outside via a connector 59.

[0161] The connection substrate 5 can be, for example, a printed wiring substrate. The connection substrate 5 has a structure formed by laminating a base layer and a wiring layer (not shown). For example, glass epoxy resin can be used for the base layer. As the material of the wiring layer, for example, metals such as copper, silver, palladium, iridium, platinum, and gold can be used.

[0162] The heat dissipation member 8 has a function of dissipating heat from the substrate 10. The substrate 10 and the connection substrate 5 are mounted on the heat dissipation member 8. For example, metal such as aluminum can be used as the heat dissipation member 8.

[0163] The thermal printer of this embodiment can include the above-mentioned single-chip substrate. The thermal printer performs printing on a printing medium. Examples of the printing medium include thermal paper used to make barcode paper or receipts.

[0164] The thermal printer includes, for example, a thermal print head 200 , a platen roller 91 , a main power circuit, a measurement circuit, and a control unit. The platen roller 91 faces the thermal print head 200 .

[0165] The main power supply circuit supplies power to the plurality of heating resistors 18a in the thermal print head 200. The measuring circuit measures the resistance value of each of the plurality of heating resistors 18a. The measuring circuit measures the resistance value of each of the plurality of heating resistors 18a, for example, when printing is not being performed on a print medium. In this way, it is possible to confirm the life of the heating resistor 18a or the presence or absence of a failed heating resistor 18a. The control unit controls the driving state of the main power supply circuit and the measuring circuit. The control unit controls the power-on state of each of the plurality of heating resistors 18a. There is a case where the measuring circuit is omitted.

[0166] The connector 59 is used for communication with a device outside the thermal print head 200. The thermal print head 200 is electrically connected to a main power supply circuit and a measurement circuit via the connector 59. The thermal print head 200 is electrically connected to a control unit via the connector 59.

[0167] The driver IC 7 receives a signal from the control unit via the connector 59. Based on the signal received from the control unit, the driver IC 7 controls the power-on state of each of the plurality of heating resistors 18a. Specifically, the driver IC 7 selectively energizes the plurality of individual electrodes (second electrodes 20b) to cause any of the plurality of heating resistors 18a to generate heat.

[0168] Next, the method of using the thermal printer is described.

[0169] When printing on a printing medium, the main power circuit applies a potential v11 to the connector 59 as the potential V1. In this case, the plurality of heating resistors 18a are selectively energized to generate heat. The heat is transferred to the printing medium, thereby completing printing on the printing medium. As described above, when the main power circuit applies a potential v11 to the connector 59 as the potential V1, a current path to each of the plurality of heating resistors 18a can be ensured.

[0170] When printing is not performed on the printing medium, the resistance value of each heating resistor section 18a is measured. During this measurement, the potential is not given to the connector 59 from the main power supply circuit. When measuring the resistance value of each heating resistor section 18a, the potential v12 is given to the connector 59 as the potential V1 from the measuring circuit. In this case, multiple heating resistor sections 18a are energized in sequence (for example, starting from the heating resistor section 18a at the end of the main scanning direction Y in sequence). The measuring circuit measures the resistance value of each heating resistor section 18a based on the value of the current flowing in the heating resistor section 18a and the potential v12. As described above, when the potential v11 is given to the connector 59 as the potential V1 from the main power supply circuit, the power supply path to each of the multiple heating resistor sections 18a is substantially blocked. As a result, the resistance value of each heating resistor section 18a can be measured more accurately by the measuring circuit, and the life of the heating resistor section 18a or the presence or absence of a failed heating resistor section 18a can be confirmed.

[0171] According to the present embodiment, it is possible to obtain a thermal printer that can form a high-definition electrode pattern by reducing the electrode pitch, can ensure a good yield, and can realize high-definition printing on a printing medium.

[0172] [Other embodiments]

[0173] As mentioned above, several embodiments are described, and the description and drawings constituting a part of the disclosure are illustrative and should not be construed as limiting. According to the disclosure, a person skilled in the art can understand various alternative embodiments, examples and application technologies. Like this, the present embodiment includes various embodiments not described herein, etc.

[0174] For example, the single-piece substrate 100 of the first embodiment may have a structure including the heat storage layer including two types of layers as described in the second embodiment.

[0175] <Example of Implementation>

[0176] The following are examples of embodiments of the present invention. The embodiments of the present invention are not limited to the following examples.

[0177] [Supplementary Note 1] A thermal print head, comprising: a heat storage layer having a first layer and a second layer on the first layer; wiring formed on the heat storage layer; a heating resistor formed on the wiring; and a protective film covering the heat storage layer, the wiring and the heating resistor, wherein the first layer comprises glass and the second layer is a porous layer.

[0178] [Supplementary Note 2] In the thermal print head described in [Supplementary Note 1], the film thickness of the second layer is smaller than the film thickness of the first layer.

[0179] [Supplement 3] In the thermal print head described in [Supplement 1] or [Supplement 2], the second layer includes porous glass.

[0180] [Supplement 4] In the thermal print head according to any one of [Supplement 1] to [Supplement 3], a distance between adjacent wirings is not less than 10 μm and not more than 50 μm.

[0181] [Supplementary Note 5] In the thermal print head according to any one of [Supplementary Note 1] to [Supplementary Note 3], the center-to-center spacing between adjacent wirings is greater than 40 μm and less than 70 μm.

[0182] [Supplement 6] A thermal printer comprising a thermal print head as described in any one of [Supplement 1] to [Supplement 5].

[0183] [Supplementary Note 7] A method for manufacturing a thermal print head, comprising forming a first layer comprising glass on a substrate, and forming a second layer as a porous layer on the first layer, thereby forming a heat storage layer comprising the first layer and the second layer, forming wiring on the heat storage layer, forming a heating resistor on the wiring, and forming a protective film covering the heat storage layer, the wiring and the heating resistor.

[0184] [Supplement 8] A method for manufacturing a thermal print head as described in [Supplement 7], comprising applying a first glass paste, drying the applied first glass paste, applying a second glass paste on the dried first glass paste, drying the applied second glass paste, and firing the dried first glass paste and the second glass paste to form a first layer containing glass and a second layer which is a porous layer, thereby forming the heat storage layer.

[0185] [Supplementary Note 9] In the method for manufacturing a thermal print head as described in [Supplementary Note 7] or [Supplementary Note 8], the thickness of the second layer is smaller than the thickness of the first layer.

[0186] [Supplement 10] In the method for manufacturing a thermal print head as described in any one of [Supplement 7] to [Supplement 9], the second layer contains porous glass.

[0187] [Supplement 11] In the method for manufacturing a thermal print head as described in any one of [Supplement 7] to [Supplement 10], a distance between adjacent wirings is 10 μm to 50 μm.

[0188] [Supplement 12] In the method for manufacturing a thermal print head as described in any one of [Supplement 7] to [Supplement 10], the center-to-center spacing between adjacent wirings is greater than 40 μm and less than 70 μm.

[0189] The present invention is related to the subject matter of Japanese Patent Application No. 2020-133780 filed on August 6, 2020 and the subject matter of Japanese Patent Application No. 2020-145965 filed on August 31, 2020, the entire disclosures of which are incorporated herein by reference.

[0190] Explanation of symbols

[0191] 5. Connect the substrate

[0192] 7. Driver IC

[0193] 8 Heat dissipation components

[0194] 10, 10a, 115 substrate

[0195] 10A upper surface

[0196] 11 convex part

[0197] 11A top surface

[0198] 11B side view

[0199] 12, 26 wiring layers

[0200] 12a, 26a conductive film

[0201] 14, 17 insulation layer

[0202] 14a, 24 insulation film

[0203] 15Resist pattern

[0204] 16.133 heat storage layer

[0205] 18 Resistor layer

[0206] 18a, 141 heating resistor

[0207] 19a, 19b opening

[0208] 20a first electrode

[0209] 20b Second electrode

[0210] 20b1 single pad

[0211] 20c, 20d connection wiring

[0212] 20d1 Heating pad

[0213] 22, 134 protective film

[0214] 59 Connector

[0215] 91 Paper pressing roller

[0216] 92 Printing media

[0217] 100, 100A single chip substrate

[0218] 131 Single Electrode

[0219] 132 Common electrode

[0220] 132A Comb Teeth

[0221] 132B Public Department

[0222] 133aFirst floor

[0223] 133b Second floor

[0224] 200 thermal print head

Claims

1. A thermal print head, characterized in that: include: a substrate having a protrusion; a wiring layer on the protrusion; A heat storage layer on the wiring layer; A heating resistor portion formed on the heat storage layer and arranged along the main scanning direction; a first electrode in contact with the heat generating resistor portion at one side in the sub-scanning direction; a second electrode in contact with the heating resistor portion on the other side in the sub-scanning direction; and a connecting wiring formed in an opening portion that penetrates the heating resistor portion and the heat storage layer and reaches the wiring layer, The first electrode is electrically connected to the wiring layer via the connecting wiring. The first electrode is a common electrode, The second electrode is a single electrode.

2. The thermal print head according to claim 1, wherein: The wiring layer includes silicide.

3. The thermal print head according to claim 1, wherein: The wiring layer covers the upper surface and side surfaces of the protrusion.

4. The thermal print head according to claim 1, wherein: The wiring layer includes metal.

5. The thermal print head according to claim 1, wherein: The substrate and the protrusion are integrally formed of a single crystal semiconductor.

6. The thermal print head according to claim 5, characterized in that: The single crystal semiconductor is composed of silicon.

7. A thermal printer, characterized in that: A thermal print head according to any one of claims 1 to 6.

8. A method for manufacturing a thermal print head, characterized in that: A wiring film is formed on the surface of the substrate. The substrate and a portion of the wiring film are removed to form a protrusion and a wiring layer on the protrusion, forming a heat storage layer on the wiring layer, A heating resistor portion arranged along the main scanning direction is formed on the heat storage layer, forming an opening portion penetrating the heating resistor portion and the heat storage layer and reaching the wiring layer, A connecting wiring is formed in the opening, and a first electrode electrically connected to the wiring layer via the connecting wiring, and a second electrode spaced apart from the first electrode in a manner sandwiching the heating resistor portion along a sub-scanning direction is formed. The first electrode is a common electrode, The second electrode is a single electrode.

9. The method for manufacturing a thermal print head according to claim 8, wherein: The wiring film is formed by silicidizing a substrate.

10. A method for manufacturing a thermal print head, characterized in that: A portion of the substrate is removed to form a convex portion. forming an oxide film on the substrate, forming a wiring layer on the oxide film, forming a heat storage layer on the wiring layer, A plurality of heating resistors are formed on the heat storage layer and arranged along the main scanning direction. forming an opening portion penetrating the heating resistor portion and the heat storage layer and reaching the wiring layer, A connecting wiring is formed in the opening, and a first electrode electrically connected to the wiring layer via the connecting wiring, and a second electrode spaced apart from the first electrode in a manner sandwiching the heating resistor portion along a sub-scanning direction is formed. The first electrode is a common electrode, The second electrode is a single electrode.

11. The method for manufacturing a thermal print head according to any one of claims 8 to 10, characterized in that: The protrusions are formed by anisotropic etching using potassium hydroxide.

12. The method for manufacturing a thermal print head according to any one of claims 8 to 10, characterized in that: The substrate is composed of a single crystal semiconductor.

13. The method for manufacturing a thermal print head according to claim 12, wherein: The single crystal semiconductor is composed of silicon.

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