Thermal head and thermal printer

Abstract

A thermal head is provided with a substrate (7), a bonding material (24), a conductive member (11b), and an aluminum electrode (19). The bonding material (24) is located on the substrate (7) and contains gold and tin. The conductive member (11b) is positioned on the bonding material (24). The aluminum electrode (19) is located on the substrate (7) and is electrically connected to the conductive member (11b) via the bonding material (24).

Description

Technical Field

[0001] The disclosed embodiments relate to a thermal head and a thermal printer. Background Art

[0002] Conventionally, various thermal heads have been proposed as printing devices such as facsimile machines and video printers. For example, there is known a connection structure for electronic components in which aluminum wiring on a substrate is plated and then bonded using a bonding material.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 61-244567 Summary of the invention

[0006] A thermal head according to one embodiment of the present invention comprises a substrate, a bonding material, a conductive member, and an aluminum electrode. The bonding material is located on the substrate and contains gold and tin. The conductive member is located on the bonding material. The aluminum electrode is located on the substrate and is electrically connected to the conductive member via the bonding material.

[0007] In addition, a thermal printer according to one aspect of the present disclosure includes the thermal head described above, a conveying mechanism, and a platen roller. The conveying mechanism conveys a recording medium onto a heat generating portion located on a substrate. The platen roller presses the recording medium. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is an exploded perspective view schematically showing a thermal head according to the embodiment.

[0009] Figure 2 It is shown Figure 1 A schematic top view of a thermal head is shown.

[0010] Figure 3 yes Figure 2 Sectional view along line III-III.

[0011] Figure 4 yes Figure 3 An enlarged cross-sectional view of area A is shown.

[0012] Figure 5 yes Figure 4 An enlarged cross-sectional view of region B is shown.

[0013] Figure 6 Schematic diagram of a thermal printer according to an embodiment. DETAILED DESCRIPTION

[0014] In the conventional connection structure, there is room for improvement in durability.

[0015] Therefore, it is desired to provide a thermal head and a thermal printer having high durability.

[0016] Hereinafter, embodiments of the thermal head and thermal printer disclosed in the present application will be described with reference to the accompanying drawings. It should be noted that the present invention is not limited to the embodiments described below.

[0017] <Implementation Method>

[0018] Figure 1 1 is an exploded perspective view showing an overview of a thermal head according to an embodiment of the present invention. Figure 1 As shown, the thermal head X1 of the embodiment includes a head base 3, a connector 31, a sealing member 12, a heat sink 1, and an adhesive member 14. Figure 1 The structure of the thermal head X1 shown is just an example, and for example, it may not necessarily include one or more of the connector 31 , the sealing member 12 , the heat sink 1 , and the adhesive member 14 .

[0019] The heat sink 1 dissipates the excess heat of the head base 3. The head base 3 is placed on the heat sink 1 via the adhesive member 14. The head base 3 is radiated on the recording medium P (see FIG. 1 ) by applying a voltage from the outside. Figure 6 ) for printing. The bonding member 14 bonds the head base 3 and the heat sink 1. The connector 31 electrically connects the head base 3 to the outside. The connector 31 has a connector pin 8 and a housing 10. The sealing member 12 joins the connector 31 to the head base 3.

[0020] The heat sink 1 is in the shape of a rectangular parallelepiped and is formed of a metal material such as copper, iron, or aluminum, and dissipates heat that does not contribute to printing, among the heat generated by the heat generating portion 9 of the head base 3 .

[0021] The head base 3 is rectangular in plan view, and each component constituting the thermal head X1 is arranged on a substrate 7. The head base 3 prints a signal on the recording medium P (see FIG. 1 ) according to an electrical signal supplied from the outside. Figure 6 ) for printing.

[0022] Next, use Figure 2 , Figure 3 , each component constituting the thermal head X1 is further described. Figure 2 It is shown Figure 1 A schematic top view of a thermal head is shown. Figure 3 yes Figure 2 It should be noted that in Figure 2 In FIG. 1 , the protective layer 25 , the coating layer 27 , and the sealing member 12 are indicated by a dashed line, and the coating member 29 is indicated by a dotted line.

[0023] The head base 3 includes a substrate 7, a heating resistor 15, a common electrode 17, an independent electrode 19, a first connection electrode 21, a second connection electrode 26, a ground electrode 4, a connection terminal 2, a conductive member 23, a driver IC 11, a bonding material 24, a covering member 29, a protective layer 25, and a covering layer 27. It should be noted that the head base 3 may not necessarily include all of these components. In addition, the head base 3 may also include components other than these.

[0024] The substrate 7 is arranged on the heat sink 1 and has a rectangular shape when viewed from above. The substrate 7 has a first surface 7f, a second surface 7g, and a side surface 7e. The first surface 7f has a first long side 7a, a second long side 7b, a first short side 7c, and a second short side 7d. The components constituting the head base 3 are arranged on the first surface 7f. The second surface 7g is located on the side opposite to the first surface 7f. The second surface 7g is located on the heat sink 1 side and is bonded to the heat sink 1 via an adhesive member 14. The side surface 7e connects the first surface 7f and the second surface 7g and is located on the second long side 7b side.

[0025] The substrate 7 is formed of, for example, an electrically insulating material such as alumina ceramics or a semiconductor material such as single crystal silicon. Hereinafter, for convenience of explanation, the first surface 7f is sometimes referred to as the "upper surface" and the second surface 7g is sometimes referred to as the "lower surface". Similarly, the first surface 7f side is sometimes referred to as the "upper" or "above" and the second surface 7g side is sometimes referred to as the "lower" or "below" based on the side surface 7e.

[0026] The substrate 7 may also include a heat storage layer 13 located on the first surface 7f. The heat storage layer 13 may also include a base portion 13a and a raised portion 13b. The base portion 13a is located on the entire surface of the first surface 7f. The raised portion 13b is raised from the base portion 13a in the thickness direction of the substrate 7. In other words, the raised portion 13b protrudes in a direction away from the first surface 7f.

[0027] The raised portion 13b is arranged adjacent to the first long side 7a of the substrate 7 and extends along the main scanning direction. The cross section of the raised portion 13b may also be a substantially semi-elliptical shape. Thus, the protective layer 25 located on the heating portion 9 is aligned with the printed recording medium P (see Figure 6 ) is in good contact. The height of the heat storage layer 13 including the base portion 13a and the raised portion 13b from the first surface 7f of the substrate 7 may be, for example, 30 to 60 μm. The raised portion 13b is an example of glaze.

[0028] The heat storage layer 13 is formed of, for example, glass having low thermal conductivity, and temporarily stores a part of the heat generated by the heat generating portion 9. Therefore, the time required to increase the temperature of the heat generating portion 9 can be shortened, and the thermal response characteristics of the thermal head X1 can be improved.

[0029] The heat storage layer 13 is formed, for example, by applying a predetermined glass paste obtained by mixing glass powder with an appropriate organic solvent to the first surface 7 f by screen printing or the like, performing etching treatment as necessary, and then firing the paste.

[0030] The heating resistor 15 is located on the upper surface of the heat storage layer 13. The common electrode 17 and the independent electrode 19 are located on the heating resistor 15. The exposed area of ​​the heating resistor 15 is located between the common electrode 17 and the independent electrode 19. Figure 2 As shown, the exposed areas of the heating resistors 15 are located in a row on the raised portion 13 b of the heat storage layer 13 , and each exposed area constitutes a respective element of the heating portion 9 .

[0031] It should be noted that the heating resistor 15 does not necessarily need to be located between various electrodes and the thermal storage layer 13. The heating resistor 15 may also be located only between the common electrode 17 and the independent electrode 19 to electrically connect the common electrode 17 and the independent electrode 19. In addition, the heating resistor 15 may be located between the first connection electrode 21 and the second connection electrode 26 and the thermal storage layer 13, or between the ground electrode 4 and the thermal storage layer 13.

[0032] For convenience of explanation, each element of the heating unit 9 composed of a plurality of heating resistors 15 is Figure 2 Although the description is simplified in FIG. 1 , the heating resistor 15 is arranged at a density of, for example, 100 dpi to 2400 dpi (dot per inch). The heating resistor 15 is formed of a relatively high resistance material such as TaN, TaSiO, TaSiNO, TiSiO, TiSiCO or NbSiO. Therefore, when a voltage is applied to the heating portion 9, the heating portion 9 generates heat due to Joule heating.

[0033] The common electrode 17 includes main wiring portions 17a and 17d, a sub-wiring portion 17b, and a lead portion 17c. The common electrode 17 electrically connects the plurality of elements constituting the heat generating portion 9 to the connector 31. The main wiring portion 17a extends along the first long side 7a of the substrate 7. The sub-wiring portion 17b extends along the first short side 7c and the second short side 7d of the substrate 7, respectively. The lead portion 17c extends independently from the main wiring portion 17a toward each heat generating portion 9. The main wiring portion 17d extends along the second long side 7b of the substrate 7.

[0034] The independent electrode 19 electrically connects the heat generating part 9 and the driver IC 11. In addition, the plurality of elements constituting the heat generating part 9 are divided into a plurality of groups. The independent electrode 19 electrically connects the elements constituting the heat generating part 9 of each group and the driver IC 11 corresponding to each group. The independent electrode 19 is electrically connected to the driver IC 11 through the bonding material 24.

[0035] The first connection electrodes 21 electrically connect the driver IC 11 and the connector 31. The plurality of first connection electrodes 21 connected to the respective driver ICs 11 are composed of a plurality of wirings having different functions.

[0036] The second connection electrodes 26 electrically connect adjacent driver ICs 11. The plurality of second connection electrodes 26 are composed of a plurality of wirings having different functions.

[0037] The common electrode 17, the first connection electrode 21 and the second connection electrode 26 are formed of a conductive material and may be made of, for example, aluminum, gold, silver and copper or an alloy thereof.

[0038] The independent electrode 19 is a so-called aluminum electrode. The independent electrode 19 contains, for example, aluminum or an aluminum alloy and has conductivity.

[0039] The ground electrode 4 is surrounded by the individual electrode 19, the first connection electrode 21, and the main wiring portion 17d of the common electrode 17. The ground electrode 4 is maintained at a ground potential of 0 to 1V.

[0040] The thickness of the independent electrode 19 is, for example, 0.5 μm or less, and may be, for example, about 0.1 μm to 0.5 μm. This makes it difficult for the heat generated by the heat generating portion 9 to be dissipated through the independent electrode 19. In addition, by reducing the height difference with the substrate 7, for example, the protective layer 25 covering the heat generating portion 9 is not easily peeled off, and the reliability of the thermal head X1 is improved.

[0041] The thickness of the electrodes other than the independent electrode 19 is, for example, about 0.1 μm to 10 μm, or about 0.3 μm to 5 μm. The thickness of the electrodes other than the independent electrode 19 may be the same as that of the independent electrode 19 .

[0042] The connection terminal 2 is located on the second long side 7b of the substrate 7, and connects the common electrode 17, the independent electrode 19, the first connection electrode 21, and the ground electrode 4 to the connector 31. The connection terminal 2 is configured to correspond to the connector pin 8, and when the connector 31 is connected, the connector pin 8 and the connection terminal 2 are connected in an electrically independent manner.

[0043] like Figure 3 As shown, the conductive member 23 is located on each connection terminal 2. As the conductive member 23, for example, solder or ACP (Anisotropic Conductive Paste) can be exemplified. It should be noted that a plating layer formed of, for example, Ni, Au, or Pd may be located between the conductive member 23 and the connection terminal 2.

[0044] The various electrodes constituting the head base 3 can be formed by, for example, sequentially stacking metal material layers such as Al, Au, Ag, Cu or Ni constituting the electrodes on the heat storage layer 13 using a thin film forming technique such as a sputtering method, and then processing the stacked body into a predetermined pattern using photolithography or the like. It should be noted that the various electrodes constituting the head base 3 can be formed simultaneously by the same process. In addition, various electrodes can also be produced by, for example, screen printing, flexographic printing, gravure printing, gravure offset printing, etc.

[0045] The driver IC 11 is located, for example, on the first surface 7f side of the substrate 7. In addition, a plurality of driver ICs 11 are arranged along the arrangement direction of the heating portion 9 in a manner corresponding to each element of the heating portion 9 assigned to each driver IC 11. The driver IC 11 is connected to the independent electrode 19 and the first connection electrode 21. The driver IC 11 controls the power-on state of the heating portion 9. The driver IC 11 supplies power to the heating portion 9 for independently generating heat for each element of the heating portion 9 in accordance with an electrical signal supplied from the outside. As the driver IC 11, for example, a switch IC having a plurality of switching elements inside can be used.

[0046] The bonding material 24 is located on the independent electrode 19 and electrically connects the driver IC 11 to the independent electrode 19. The bonding material 24 contains gold (Au) and tin (Sn) and has conductivity. The bonding material 24 has high mechanical strength such as shear stress and is difficult to peel off from the independent electrode 19, so the durability becomes high. It should be noted that the details of the bonding between the independent electrode 19 and the driver IC 11 by the bonding material 24 will be described later.

[0047] The protective layer 25 is disposed on the heat storage layer 13 located on the first surface 7f side of the substrate 7. The protective layer 25 covers the heating resistor 15, the common electrode 17 and the independent electrode 19 including the heating portion 9. More specifically, the protective layer 25 covers a portion of the independent electrode 19 from the edge of the substrate 7, that is, the first long side 7a, the first short side 7c and the second short side 7d of the substrate 7. The protective layer 25 protects the covered area from corrosion caused by the adhesion of moisture contained in the atmosphere, or from corrosion caused by contact with the recording medium P (see Figure 6 As the protective layer 25, for example, SiN, SiON, SiO2, SiAlON, TiN, TiON, TiCrN, TiAlON, etc. can be used.

[0048] The coating layer 27 is located on the first surface 7f side of the substrate 7. The coating layer 27 partially covers the common electrode 17, the independent electrode 19, the first connection electrode 21, and the second connection electrode 26. The coating layer 27 protects the coated area from oxidation caused by contact with the atmosphere or corrosion caused by adhesion of moisture contained in the atmosphere. As the coating layer 27, for example, a resin material such as an epoxy resin, a polyimide resin, or a silicone resin can be used.

[0049] The covering member 29 seals the driver IC 11 while connecting the driver IC 11 to the independent electrode 19, the second connection electrode 26, and the first connection electrode 21. The covering member 29 is arranged to extend along the main scanning direction and integrally seals the plurality of driver ICs 11. As the covering member 29, for example, a resin material such as an epoxy resin or a silicone resin can be used.

[0050] The connector 31 has a plurality of connector pins 8 and a housing 10 that accommodates the plurality of connector pins 8. The connector pins 8 have a first end and a second end, and are electrically connected to various electrodes of the head base 3. The first end is exposed to the outside of the housing 10 and is electrically connected to the connection terminal 2 of the head base 3. The second end is housed inside the housing 10 and led to the outside.

[0051] The sealing member 12 includes a first sealing member 12a and a second sealing member 12b. The first sealing member 12a is located on the first surface 7f of the substrate 7. The first sealing member 12a seals the connector pin 8 and various electrodes. The second sealing member 12b is located on the second surface 7g of the substrate 7. The second sealing member 12b is configured to seal the contact portion between the connector pin 8 and the substrate 7.

[0052] The sealing member 12 is configured in a manner that the connection terminal 2 and the connector pin 8 are not exposed to the outside. The sealing member 12 can be composed of, for example, a thermosetting resin of an epoxy system, a UV-curable resin, or a visible light-curable resin. It should be noted that the first sealing member 12a and the second sealing member 12b can also be composed of the same material. In addition, the first sealing member 12a and the second sealing member 12b can also be composed of different materials.

[0053] The adhesive member 14 is located on the heat sink 1. The adhesive member 14 bonds the second surface 7g of the head base 3 to the heat sink 1. As the adhesive member 14, a double-sided tape or a resin adhesive can be exemplified.

[0054] Next, use Figure 4 The main parts of the thermal head X1 of the embodiment will be described in detail. Figure 4 yes Figure 3 The enlarged cross-sectional view of the area A shown in FIG. Figure 4 In the figure, the covering member 29 is omitted.

[0055] like Figure 4 As shown, the driver IC 11 includes a component portion 11a and a terminal portion 11b. The component portion 11a is a main portion that realizes the above-mentioned function of the driver IC 11. The component portion 11a is an example of an electronic component.

[0056] The terminal portion 11b is electrically connected to the element portion 11a. The terminal portion 11b is electrically connected to the independent electrode 19 via the bonding material 24 located on the substrate 7, more specifically, located on the base portion 13a. The terminal portion 11b is, for example, a conductive metal member. The terminal portion 11b contains, for example, copper and nickel. The terminal portion 11b is an example of a conductive member.

[0057] In addition, the terminal portion 11b may include a first layer 111 and a second layer 112. The first layer 111 contains, for example, copper. The first layer 111 can improve the bonding strength between the driver IC 11 and the individual electrode 19 by, for example, alleviating thermal stress.

[0058] In addition, the second layer 112 is located closer to the substrate 7 than the first layer 111. The second layer 112 contains nickel, for example. The second layer 112 can improve the durability of the driver IC 11 by, for example, making it difficult for gold atoms and tin atoms located in the bonding material 24 to diffuse toward the element portion 11a. In addition, the second layer 112 can improve the durability of the driver IC 11 by, for example, making it difficult for copper atoms in the first layer 111 to diffuse toward the bonding material 24.

[0059] Thus, the terminal portion 11b has the first layer 111 and the second layer 112, thereby improving the bonding reliability between the driver IC 11 and the independent electrode 19. It should be noted that the terminal portion 11b may have only one of the first layer 111 and the second layer 112, or may have a further stacked structure in addition to the first layer 111 and the second layer 112.

[0060] The bonding material 24 is located between the independent electrode 19 and the terminal portion 11b of the driver IC 11. The bonding material 24 is conductive and electrically connects the independent electrode 19 to the driver IC 11. The portion of the independent electrode 19 located between the substrate 7 and the bonding material 24, that is, the portion in contact with the bonding material 24 is referred to as the bonding region 20. Figure 5 The details of the bonding region 20 will be further described.

[0061] Figure 5 yes Figure 4 An enlarged cross-sectional view of region B is shown. Figure 5 As shown, the joining region 20 may also have a first portion 201 and a second portion 202 .

[0062] The gold content of the first part 201 is greater than that of the independent electrode 19. Specifically, the first part 201 may have, for example, 65% to 75% of Au atoms and 25% to 35% of Al atoms by volume. Thus, the bonding strength between the first part 201 and the bonding material 24 is improved compared to the independent electrode 19 which is an aluminum electrode. It should be noted that the tin content of the first part 201 may be greater than that of the independent electrode 19.

[0063] The aluminum content of the second portion 202 is greater than that of the first portion 201. Specifically, the second portion 202 may contain, for example, 0% to 10% Au atoms and 90% to 100% Al atoms by volume. Thus, the bonding strength between the second portion 202 and the substrate 7 is improved compared to the first portion 201.

[0064] Thus, the bonding region 20 has the first portion 201 and the second portion 202, thereby improving the adhesion between the bonding material 24 and the bonding region 20 and the adhesion between the bonding region 20 and the substrate 7. This improves the bonding strength of the driver IC 11 and improves the durability of the thermal head X1.

[0065] Here, the central portion 20A and the end portions 20B of the bonding region 20 are defined. The central portion 20A is a portion located in the center of the bonding material 24 along the width direction. The width direction of the bonding material 24 is the connecting Figure 5 The end portion 20B is a portion located at the end of the bonding material 24 along the width direction and includes a portion in contact with the end portions 241 of the bonding material 24.

[0066] In this case, the second portion 202 may be located at the end portion 20B of the bonding region 20. When the second portion 202 is located at the end portion 20B, the adhesion between the bonding region 20 and the substrate 7 is further improved, and the separation is difficult.

[0067] In addition, regarding the area ratio of the second portion 202, the area ratio in the end portion 20B of the bonding region 20 along the width direction of the bonding material 24 may be larger than the area ratio in the central portion 20A. Here, the area ratio of the second portion 202 refers to the area ratio of the second portion 202 in the bonding region 20 when viewed in cross section. By making the area ratio of the second portion 202 in the end portion 20B larger than that in the central portion 20A, the adhesion between the bonding region 20 and the substrate 7 is further improved, making it difficult to peel off.

[0068] The first portion 201 may be thicker in the center than in the ends. Thus, by reducing the thickness of the first portion 201 at the ends of the bonding material 24 along the width direction where stress is likely to concentrate, adhesion between the bonding region 20 and the substrate 7 is improved.

[0069] It should be noted that the position and shape of the first portion 201 and the second portion 202 and the area ratio of the second portion 202 can be determined visually based on a SEM (Scanning Electron Microscope) image obtained by photographing a cross section of the independent electrode 19 including the bonding region 20. Alternatively, the diffusion state of Au, Al or Sn can be observed using EPMA (Electron Probe MicroAnalyzer) for determination.

[0070] Although not shown in the figure, the connection between the ground electrode 4 , the first connection electrode 21 , and the second connection electrode 26 and the driver IC 11 may be the same as the connection between the driver IC 11 in the above-mentioned independent electrode 19 .

[0071] Next, refer to Figure 6 A thermal printer Z1 including a thermal head X1 will be described. Figure 6 Schematic diagram of a thermal printer according to an embodiment.

[0072] The thermal printer Z1 of the embodiment includes the thermal head X1, the conveying mechanism 40, the platen roller 50, the power supply device 60, and the control device 70. The thermal head X1 is mounted on the mounting surface 80a of the mounting member 80 disposed on the frame (not shown) of the thermal printer Z1. It should be noted that the thermal head X1 is mounted on the mounting member 80 in a manner along the main scanning direction, which is a direction orthogonal to the conveying direction S.

[0073] The conveying mechanism 40 has a driving unit (not shown) and conveying rollers 43, 45, 47, 49. The conveying mechanism 40 conveys the recording medium P such as thermal paper and developing paper with ink transferred thereto to the protective layer 25 located on the plurality of heating parts 9 of the thermal head X1 in a manner along the conveying direction S indicated by the arrow. The driving unit has a function of driving the conveying rollers 43, 45, 47, 49, and a motor can be used, for example. The conveying rollers 43, 45, 47, 49 can also be cylindrical shafts 43a, 45a, 47a, 49a covered with a metal material such as stainless steel by elastic members 43b, 45b, 47b, 49b made of butadiene rubber or the like. It should be noted that, in the case where the recording medium P is developing paper with ink transferred thereto, an ink film (not shown) is conveyed together with the recording medium P between the recording medium P and the heating part 9 of the thermal head X1.

[0074] The platen roller 50 has a function of pressing the recording medium P against the protective layer 25 located on the heat generating portion 9 of the thermal head X1. The platen roller 50 is arranged to extend in a direction perpendicular to the conveying direction S, and both ends are supported and fixed in a rotatable manner while pressing the recording medium P against the heat generating portion 9. The platen roller 50 can be formed, for example, by covering a cylindrical shaft 50a formed of a metal such as stainless steel with an elastic member 50b formed of butadiene rubber or the like.

[0075] As described above, the power supply device 60 has a function of supplying current for heating the heating portion 9 of the thermal head X1 and current for operating the driver IC 11. The control device 70 has a function of supplying a control signal for controlling the operation of the driver IC 11 to the driver IC 11 in order to selectively heat the heating portion 9 of the thermal head X1 as described above.

[0076] The thermal printer Z1 presses the recording medium P against the heating portion 9 of the thermal head X1 by the platen roller 50 and conveys the recording medium P to the heating portion 9 by the conveying mechanism 40, and selectively heats the heating portion 9 by the power supply device 60 and the control device 70, thereby performing predetermined printing on the recording medium P. It should be noted that, when the recording medium P is imaging paper or the like, the recording medium P is printed by thermally transferring the ink of an ink film (not shown) conveyed together with the recording medium P to the recording medium P.

[0077] The above describes the embodiments of the present disclosure, but the present disclosure is not limited to the above embodiments, and various changes can be made as long as they do not deviate from the main purpose. For example, the example of the planar head where the heating portion 9 is located on the main surface of the substrate 7 is described, but the heating portion 9 can also be an end face head located on the end face of the substrate 7.

[0078] Furthermore, although the description has been made using a so-called thin film head that forms the heating resistor 15 by sputtering, the present invention is not limited to the thin film head and a so-called thick film head that forms the heating resistor 15 by printing or the like may be used.

[0079] Alternatively, the portion covering the bonding material 24 and the terminal portion 11b may be covered with an underfill material instead of the covering member 29. The underfill material may be made of, for example, a resin having insulating properties such as epoxy resin.

[0080] Alternatively, the heat generating portion 9 may be formed by forming the common electrode 17 and the individual electrodes 19 on the heat storage layer 13 and forming the heat generating resistor 15 only in the region between the common electrode 17 and the individual electrodes 19 .

[0081] Furthermore, although an example in which the connector 31 is directly connected to the substrate 7 is shown, a flexible printed circuit (FPC: Flexible Printed Circuits) may be connected to the substrate 7 .

[0082] Furthermore, although the thermal head X1 having the coating layer 27 is illustrated, it is not necessarily required to have the coating layer 27. In this case, the protective layer 25 may be located in the region provided with the coating layer 27. Furthermore, the coating layer 27 may be provided in a region other than that shown in the figure.

[0083] Further effects and variations can be easily derived by those skilled in the art. Therefore, the wider scope of the present disclosure is not limited to the specific detailed and representative embodiments shown and described above. Therefore, various changes can be made without departing from the spirit or scope of the concept of the general invention defined by the attached technical solutions and their equivalents.

[0084] Description of reference numerals:

[0085] X1 Thermal Head

[0086] Z1 Thermal Printer

[0087] 1 Heat sink

[0088] 3 head base

[0089] 4 Grounding electrode

[0090] 7 substrate

[0091] 9 Heating part

[0092] 11 Driver IC

[0093] 15 Heating resistor

[0094] 17 Common Electrode

[0095] 19 independent electrodes

[0096] 20 Joint area

[0097] 21 First connection electrode

[0098] 24 Bonding materials

[0099] 25 protective layer

[0100] 26 Second connection electrode

[0101] 27 Coating

[0102] 29 Covering member.

Claims

1. A thermal head, wherein: The thermal head has: substrate; a bonding material located on the substrate and containing gold and tin; a conductive member located on the bonding material; and The aluminum electrode is located on the substrate and is electrically connected to the bonding material.

2. The thermal head according to claim 1, wherein: The conductive member has a first layer containing copper and a second layer located between the first layer and the bonding material and containing nickel.

3. The thermal head according to claim 1 or 2, wherein: The aluminum electrode has a thickness of 0.5 μm or less.

4. The thermal head according to any one of claims 1 to 3, wherein: The bonding material is in contact with the aluminum electrode.

5. The thermal head according to any one of claims 1 to 4, wherein: The aluminum electrode has a bonding region between the substrate and the bonding material, The bonding region includes a first portion and a second portion. The gold content of the first portion is higher than that of the aluminum electrode. The aluminum content of the second portion is higher than that of the first portion.

6. The thermal head according to claim 5, wherein: The second portion is located at an end portion of the bonding region along the width direction of the bonding material.

7. The thermal head according to claim 6, wherein: The area ratio of the second portion is larger at the end portions of the bonding region along the width direction than at the central portion.

8. The thermal head according to any one of claims 5 to 7, wherein: The thickness of the first portion is greater in a central portion of the joining region along the width direction of the joining material than in an end portion.

9. A thermal printer, wherein: The thermal printer has: The thermal head according to any one of claims 1 to 8; a conveying mechanism for conveying the recording medium onto the heat generating portion located on the substrate; and A platen roller presses the recording medium against the heat generating portion.

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