JP6525819B2 - Thermal head and thermal printer - Google Patents

Description

  The present invention relates to a thermal head and a thermal printer.

  Conventionally, various thermal heads have been proposed as printing devices such as facsimiles and video printers. For example, a substrate, a heat generating portion provided on the substrate, an electrode provided on the substrate and electrically connected to the heat generating portion, and a pad provided on the substrate and electrically connected to the electrode The thermal head which it has is known (for example, refer patent document 1). In this thermal head, the pad has a first pad for wire bonding connected to an external terminal, and a second pad for inspection disposed at a position different from the first pad.

  Also, in order to stabilize the electrical connection of the wire bonding, a smooth layer is provided below the first pad and the second pad. Therefore, when the probe needle for inspection is applied, the probe needle slips on the second pad, and the probe mark may reach the first pad. Therefore, an insulating resist is formed on the pads so as to divide the first pad and the second pad, thereby preventing the probe mark from reaching the first pad.

Japanese Patent Application Publication No. 2003-200605

  However, in the above-described thermal head, the stability of the electrical connection of the first pad wire bonding is improved by providing a new member such as an insulating resist formed on the pad. There is a problem that the number of processes increases.

  A thermal head according to an embodiment of the present invention includes a substrate, a heat generating portion provided on the substrate, an electrode provided on the substrate and electrically connected to the heat generating portion, and the substrate. And a pad electrically connected to the electrode. Further, the pad has a first pad for wire bonding and a second pad for inspection disposed at a position different from the first pad. Also, a smooth layer is provided between the first pad and the substrate. Further, the smooth layer is not provided between the second pad and the substrate.

  A thermal printer according to an embodiment of the present invention includes the above-described thermal head, a transport mechanism for transporting a recording medium onto the heat generating portion, and a platen roller for pressing the recording medium onto the heat generating portion. .

  It is possible to improve the electrical connection stability of the wire bonding of the first pad without providing a new member such as an insulating resist.

It is an exploded perspective view showing an outline of a thermal head concerning a 1st embodiment. It is a top view which shows the thermal head shown in FIG. It is the II sectional view taken on the line shown in FIG. The thermal head shown in FIG. 1 is shown, (a) is a top view which expands and shows one part, (b) is the II-II sectional view taken on the line of FIG. 4 (a). FIG. 1 is a schematic view showing a thermal printer according to a first embodiment. It is an exploded perspective view showing an outline of a thermal head concerning a 2nd embodiment. FIG. 7 shows the thermal head shown in FIG. 6, where (a) is a plan view showing a part of the thermal head in an enlarged manner, and (b) is a sectional view taken along line III-III shown in FIG. The thermal head which concerns on 3rd Embodiment is shown, (a) is a top view which expands and shows a part, (b) is an enlarged plan view of a pad.

First Embodiment
Hereinafter, the thermal head X1 will be described with reference to FIGS. FIG. 1 schematically shows the configuration of the thermal head X1. In FIG. 2, the protective layer 25, the cover layer 27, and the sealing member 12 are omitted. Further, in FIG. 4, the covering layer 27 is omitted.

  The thermal head X 1 includes a head base 3, a connector 31, a sealing member 12, a heat sink 1, and an adhesive member 14. In the thermal head X <b> 1, the head base 3 is mounted on the heat dissipation plate 1 via the bonding member 14. The head base 3 generates heat on the heat generating portion 9 by applying an external voltage to print on a recording medium (not shown). The connector 31 electrically connects the outside and the head base 3. The sealing member 12 joins the connector 31 and the head base 3. The heat sink 1 is provided to dissipate the heat of the head base 3. The bonding member 14 bonds the head base 3 and the heat sink 1 to each other.

  The heat sink 1 has a rectangular parallelepiped shape, and the substrate 7 is mounted. The heat sink 1 is formed of, for example, a metal material such as copper, iron, or aluminum, and has a function of radiating the heat that does not contribute to the printing among the heat generated by the heat generating portion 9 of the head base 3. .

  The head substrate 3 is formed in a rectangular shape in plan view, and the respective members constituting the thermal head X 1 are provided on the substrate 7 of the head substrate 3. The head substrate 3 has a function of printing on a recording medium (not shown) in accordance with an electric signal supplied from the outside.

  The connector 31 is electrically connected to the head base 3 and electrically connects the head base 3 and an external power supply. The connector 31 has a plurality of connector pins 8 and a housing 10 for housing the plurality of connector pins 8. The plurality of connector pins 8 are disposed on the upper and lower sides of the substrate 7 so as to sandwich the substrate 7, and the connector pins 8 disposed on the upper side electrically connect the pads 2 (see FIG. 2) of the head substrate 3. It is connected.

  The sealing member 12 is provided so that the pad 2 and the connector pin 8 are not exposed to the outside, and is made of, for example, an epoxy thermosetting resin, an ultraviolet curable resin, or a visible light curable resin. It can be formed. Further, the bonding strength between the connector 31 and the head base 3 is improved.

  The bonding member 14 is disposed on the top surface of the heat dissipation plate 1 and joins the head base 3 and the heat dissipation plate 1. The adhesive member 14 can be exemplified by a double-sided tape or a resinous adhesive.

  Hereinafter, each member which comprises the head base | substrate 3 is demonstrated using FIGS.

The substrate 7 is disposed on the heat sink 1 and has a rectangular shape in plan view. Therefore, the substrate 7 has one long side 7 a, the other long side 7 b, one short side 7 c, and the other short side 7 d. The substrate 7 is made of, for example, an electrically insulating material such as alumina ceramic or a semiconductor material such as single crystal silicon.

  A heat storage layer 13 is provided on the substrate 7. The heat storage layer 13 protrudes upward of the substrate 7. The heat storage layer 13 is disposed adjacent to one long side 7 a of the substrate 7, extends in a strip along the main scanning direction, and has a substantially semi-elliptical cross section. In addition, the heat storage layer 13 functions to well press the recording medium P (see FIG. 5) to be printed against the protective layer 25 formed on the heat generating portion 9. The heat storage layer 13 is preferably provided at a height of 15 to 90 μm from the substrate 7.

  The heat storage layer 13 is formed of glass with low thermal conductivity, and temporarily accumulates part of the heat generated by the heat generating portion 9. Therefore, the time required to raise the temperature of the heat generating portion 9 can be shortened, and the heat response characteristic of the thermal head X1 can be enhanced. The heat storage layer 13 is formed, for example, by applying a predetermined glass paste obtained by mixing a suitable organic solvent with a glass powder on the upper surface of the substrate 7 by screen printing or the like known in the related art and baking it.

  The electric resistance layer 15 is provided on the upper surface of the substrate 7 and the upper surface of the heat storage layer 13, and various electrodes constituting the head substrate 3 are provided on the electric resistance layer 15. The electric resistance layer 15 is patterned in the same shape as the various electrodes constituting the head substrate 3 and has an exposed region between the common electrode 17 and the individual electrode 19 in which the electric resistance layer 15 is exposed. Each exposed area constitutes a heat generating portion 9 and is arranged in a row on the raised portion 13a.

  The plurality of heat generating portions 9 are described in a simplified manner in FIG. 2 for convenience of explanation, but are arranged at a density of, for example, 100 dpi to 2400 dpi (dot per inch). The electric resistance layer 15 is formed of, for example, a material having a relatively high electric resistance, such as a TaN system, a TaSiO system, a TaSiNO system, a TiSiO system, a TiSiCO system, or a NbSiO system. Therefore, when a voltage is applied to the heat generating portion 9, the heat generating portion 9 generates heat by Joule heat generation.

  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 heat generating portions 9 and the connector 31. The main wiring portion 17 a extends along one long side 7 a of the substrate 7. The sub wiring portion 17 b extends along each of the short side 7 c and the other short side 7 d of the substrate 7. The lead portions 17 c individually extend from the main wiring portion 17 a toward the heat generating portions 9. The main wiring portion 17 d extends along the other long side 7 b of the substrate 7.

  The plurality of individual electrodes 19 electrically connect between the heat generating portion 9 and the drive IC 11. The individual electrodes 19 divide the plurality of heat generating portions 9 into a plurality of groups, and electrically connect the heat generating portions 9 of each group to the drive ICs 11 provided corresponding to the respective groups. A pad 4 is provided at the end of the individual electrode 19. The pad 4 is electrically connected to the drive IC 11 disposed above via the wire 18.

  The plurality of IC-connector connection electrodes 21 include signal electrodes 21 a and ground electrodes 21 b. The plurality of IC-connector connection electrodes 21 electrically connect between the drive IC 11 and the connector 31. The plurality of IC-connector connection electrodes 21 connected to each drive IC 11 are configured by a plurality of wires having different functions. The signal electrode 21 a sends various signals to the drive IC 11.

The ground electrode 21b is disposed so as to be surrounded by the individual electrode 19, the signal electrode 21a, and the main wiring portion 17d of the common electrode 17, and has a large area. The ground electrode 4 is held at a ground potential of 0 to 1V.

  The pad 2 is provided on the other long side 7 b side of the substrate 7 in order to connect the common electrode 17, the individual electrode 19, the IC-connector connection electrode 21 and the ground electrode 21 b to the connector 31. The pad 2 is provided corresponding to the connector pin 8, and when connecting to the connector 31, the connector pin 8 and the pad 2 are connected so as to be electrically independent of each other.

  The plurality of IC-IC connection electrodes 26 electrically connect adjacent drive ICs 11. The plurality of IC-IC connection electrodes 26 are provided to correspond to the IC-connector connection electrodes 21, respectively, and transmit various signals to the adjacent drive ICs 11.

  The various electrodes constituting the head substrate 3 are, for example, sequentially laminating the material layers constituting each on the heat storage layer 13 by the conventional thin film forming technology such as sputtering, for example, and then the laminated body is known conventionally. It is formed by processing into a predetermined pattern using photo etching or the like. The various electrodes constituting the head substrate 3 can be formed simultaneously by the same process.

  As shown in FIG. 2, the drive IC 11 is disposed corresponding to each group of the plurality of heat generating portions 9, and a wire is connected to the other end of the individual electrode 19 and one end of the IC-connector connection electrode 21. Connected via 18 The drive IC 11 has a function of controlling the energization state of each heat generating portion 9. As the drive IC 11, a switching member having a plurality of switching elements inside may be used.

  The driving IC 11 is sealed by a covering member 29 made of a resin such as an epoxy resin or a silicone resin in a state of being connected to the individual electrode 19, the IC-IC connecting electrode 26 and the IC-connector connecting electrode 21.

  As shown in FIG. 3, on the heat storage layer 13 provided on the substrate 7, a protective layer 25 that covers the heating portion 9, a part of the common electrode 17 and a part of the individual electrode 19 is formed.

The protective layer 25 protects the area covered with the heat generating portion 9, the common electrode 17 and the individual electrode 19 from corrosion due to adhesion of moisture contained in the atmosphere or abrasion due to contact with a recording medium to be printed. belongs to. The protective layer 25 can be formed using SiN, SiO ₂ , SiON, SiC, diamond like carbon or the like, and the protective layer 25 may be formed as a single layer, or these layers are laminated. You may Such a protective layer 25 can be manufactured using a thin film forming technique such as a sputtering method or a thick film forming technique such as screen printing.

  Further, as shown in FIG. 3, a covering layer 27 partially covering the common electrode 17, the individual electrode 19 and the IC-connector connection electrode 21 is provided on the substrate 7. The covering layer 27 is formed by oxidation of the covered area of the common electrode 17, the individual electrode 19, the IC-IC connection electrode 26 and the IC-connector connection electrode 21 by contact with the air, water contained in the air, etc. It has a function to protect from corrosion due to adhesion.

  The connector 31 and the head base 3 are fixed by the connector pin 8, the bonding member 23, and the sealing member 12. The bonding member 23 is disposed between the pad 2 and the connector pin 8, and for example, it is possible to exemplify an anisotropic conductive adhesive or the like in which conductive particles are mixed in a solder or an electrically insulating resin. Can. The thermal head X1 will be described using solder as the bonding member 23.

  A plated layer (not shown) of Ni, Au or Pd may be provided between the bonding member 23 and the pads 2 and 4. The joint member 23 may not necessarily be provided between the pad 2 and the connector pin 8. In this case, the pad 2 and the connector pin 8 may be directly electrically connected by holding the substrate 7 with the connector pin 8 using the clip type connector pin 8.

  The sealing member 12 has a first sealing member 12 a and a second sealing member 12 b. The first sealing member 12 a is located on the upper surface of the substrate 7, and the second sealing member 12 b is located on the side and lower surfaces of the substrate 7. The first sealing member 12 a is provided to seal the connector pin 8 and various electrodes, and the second sealing member 12 b is provided to reinforce the connector pin 8. In addition, the 1st sealing member 12a and the 2nd sealing member 12b may be formed of the same material, and may be formed of another material.

  The pad 4 and the smooth layer 16 will be described in detail with reference to FIG. The pad 4 is electrically connected to the individual electrode 19 and has a first pad 4 a and a second pad 4 b. The first pad 4a is formed for wire bonding. The second pad 4b is provided side by side with the first pad 4a in the sub scanning direction, and is formed continuously with the first pad 4a. The second pad 4 b is provided for electrical inspection.

  A plurality of pads 4 are provided in the main scanning direction to form a pad row. A plurality of pad rows are provided in the sub-scanning direction, and FIG. 4 shows an example in which three rows are provided.

  The smoothing layer 16 is provided between the first pad 4 a and the substrate 7 and is not provided between the second pad 4 b and the substrate 7. The smooth layer 16 is provided to extend in the main scanning direction, and is provided from one short side 7c (see FIG. 2) of the substrate 7 to the other short side 7d (see FIG. 2) of the substrate 7.

  The smooth layer 16 is provided on the substrate 7, and the surface roughness of the smooth layer 16 is smaller than the surface roughness of the substrate 7. Therefore, since the first pad 4a is provided on the flat smooth layer 16 on the surface, when the wire 18 (see FIG. 2) is formed, the electrical connection between the wire 18 and the first pad 4a is It can be stabilized.

  The smooth layer 16 can be formed of, for example, the same glass as the heat storage layer 13 (see FIG. 2), and its thickness can be 0.1 to 50 μm. The smooth layer 16 may be formed of, for example, an inorganic material such as SiN or SiON.

  Here, when the thermal head X1 performs resistance measurement, open / short inspection, and other electrical inspections of the heat generating portion 9, the probe needle is pressed against the second pad 4b. At that time, a so-called probe mark is generated on the second pad 4b. Then, the probe needle may reach the first pad 4a by sliding on the second pad 4b, and a probe mark may be formed on the first pad 4a. As a result, the surface of the first pad 4a may be roughened by a probe mark, and the electrical connection between the wire 18 and the first pad 4a may not be stable.

On the other hand, in the thermal head X 1, the smooth layer 16 is provided between the first pad 4 a and the substrate 7, and the smooth layer 16 is not provided between the second pad 4 b and the substrate 7. have. As a result, the probe needle does not slip on the second pad 4b without forming a new member such as an insulating resist on the pad 4, and the probe needle on the first pad 4a. The possibility of reaching can be reduced. As a result, the possibility of the formation of a probe mark on the first pad 4a can be reduced without providing a new member, and the stability of the electrical connection between the wire 18 and the first pad 4a can be reduced. Can be secured.

  In addition, since the smooth layer 16 is provided between the first pad 4 a and the substrate 7 and the smooth layer 16 is not provided between the second pad 4 b and the substrate 7, the first pad 4 a At the boundary between the second pad 4b and the second pad 4b, a step 4c is formed by the step 16a of the smooth layer 16.

  Therefore, when the probe needle is pressed against the second pad 4b and the electrical inspection is performed, the probe needle is hard to reach the first pad 4a due to the step 4c. As a result, the possibility of the probe needle reaching the first pad 4a can be reduced, and the possibility of the formation of a probe mark on the first pad 4a can be reduced. Therefore, the stability of the electrical connection between the wire 18 and the first pad 4a can be ensured.

  The boundary between the first pad 4a and the second pad 4b indicates a region extending in the vertical direction when the cross section is cut in the thickness direction.

  In addition, the surface roughness of the second pad 4b is greater than the surface roughness of the first pad 4a. As a result, the prober needle pressed onto the second pad 4b does not slip on the second pad 4b. As a result, the possibility of the probe needle reaching the first pad 4a can be reduced, and the possibility of the formation of a probe mark on the first pad 4a can be reduced.

  The surface roughness of the first pad 4 a is 0.01 to 0.05 in arithmetic mean height (Sa), and the surface roughness of the second pad 4 b is 0.1 to 0. 5 in arithmetic mean height (Sa). 5 is preferable. Thereby, the stability of the electrical connection between the wire 18 and the first pad 4a can be ensured.

  The surface roughness of the first pad 4a is determined by cutting the thermal head X1 in the thickness direction, taking a cross-sectional picture with a camera, and measuring the surface roughness of the first pad 4a in the cross-sectional picture. be able to. The same applies to the second pad 4b. Alternatively, the height of the surface may be measured with a noncontact laser microscope to determine the surface roughness of the first pad 4a and the second pad 4b.

  The smoothing layer 16 is provided to extend in the main scanning direction, is provided between the plurality of first pads 4 a and the substrate 7, and is formed of glass. Therefore, the smooth layer 16 common to the plurality of first pads 4 a is provided, and the heat capacity of each first pad 4 a is equalized by the smooth layer 16.

  At the time of wire bonding, heat is applied from the lower side of the substrate 7 to activate the first pad 4 a and perform wire bonding. Therefore, the heat given at the time of wire bonding is stored in the smooth layer 16 and warms the plurality of first pads 4a. As a result, the temperature of each first pad 4a is equalized, and the stability of the electrical connection between the wire 18 and the first pad 4a can be ensured.

  When forming the smooth layer 16 with glass, when forming the thermal storage layer 13, patterning of the smooth layer 16 is simultaneously performed and it can form by printing and baking glass. When the smooth layer 16 is formed of an inorganic material such as SiN or SiON, patterning of the smooth layer 16 is performed simultaneously with the formation of the protective layer 25 and the inorganic material such as SiN or SiON is sputtered. It can be formed by film formation.

  In the thermal head X1, the smooth layer 16 common to the plurality of first pads 4a is provided. However, the present invention is not limited to this. For example, an independent smoothing layer 16 may be provided for each first pad 4a. Also in this case, the surface of the first pad 4a can be smoothed, and the stability of the electrical connection between the wire 18 and the first pad 4a can be ensured.

  Next, the thermal printer Z1 will be described with reference to FIG.

  As shown in FIG. 5, the thermal printer Z1 of the present embodiment includes the above-described thermal head X1, a transport mechanism 40, a platen roller 50, a power supply device 60, and a control device 70. The thermal head X1 is mounted on a mounting surface 80a of a mounting member 80 provided on a housing (not shown) of the thermal printer Z1. The thermal head X1 is attached to the mounting member 80 along the main scanning direction which is a direction perpendicular to the conveyance direction S of the recording medium P described later.

  The transport mechanism 40 has a drive unit (not shown) and transport rollers 43, 45, 47 and 49. Conveying mechanism 40 conveys recording medium P such as thermal paper, image receiving paper to which ink is transferred in the direction of arrow S in FIG. 5, and places protective layer 25 located on heat generating portions 9 of thermal head X1. It is for carrying. The drive unit has a function of driving the transport rollers 43, 45, 47, and 49, and for example, a motor can be used. The conveying rollers 43, 45, 47 and 49 cover cylindrical shaft bodies 43a, 45a, 47a and 49a made of metal such as stainless steel with elastic members 43b, 45b, 47b and 49b made of butadiene rubber etc. Can be configured. Although not shown, when the recording medium P is an image receiving paper or the like to which the ink is transferred, the ink film is conveyed together with the recording medium P between the recording medium P and the heat generating portion 9 of the thermal head X1.

  The platen roller 50 has a function of pressing the recording medium P onto the protective film 25 located on the heat generating portion 9 of the thermal head X1. The platen roller 50 is disposed to extend along a direction orthogonal to the conveyance direction S of the recording medium P, and both ends are supported and fixed so that the recording medium P can be rotated in a state of being pressed onto the heat generating portion 9 ing. The platen roller 50 can be configured, for example, by covering a cylindrical shaft 50a made of metal such as stainless steel with an elastic member 50b made of butadiene rubber or the like.

  As described above, the power supply device 60 has a function of supplying a current for heating the heating portion 9 of the thermal head X1 and a current for operating the drive IC 11. The control device 70 has a function of supplying a control signal for controlling the operation of the drive IC 11 to the drive IC 11 in order to cause the heat generating portion 9 of the thermal head X 1 to selectively generate heat as described above.

  While the thermal printer Z1 presses the recording medium P onto the heat generating portion 9 of the thermal head X1 by the platen roller 50, the power source device 60 and the control device 70 transport the recording medium P onto the heat generating portion 9 by the transport mechanism 40. Thus, predetermined heating is performed on the recording medium P by selectively heating the heat generating portion 9. When the recording medium P is an image receiving paper or the like, printing on the recording medium P is performed by thermally transferring the ink of an ink film (not shown) conveyed together with the recording medium P onto the recording medium P.

Second Embodiment
The thermal head X2 will be described with reference to FIGS. The same members as those of the thermal head X1 are denoted by the same reference numerals, and the same applies hereinafter.

The thermal head X 2 includes the heat dissipation plate 1, the head base 103, the wiring substrate 6, and the bonding member 1.
4, a flexible wiring board 5 (hereinafter referred to as an FPC 5), and a connector 131. The thermal head X 2 is disposed such that the head substrate 103 and the wiring substrate 6 are adjacent to each other, and the head substrate 103 and the wiring substrate 6 are mounted on the heat dissipation plate 1 via the bonding member 14. .

  The wiring board 6 has a flat plate shape long in the main scanning direction, and the drive IC 11 is disposed on the upper surface. Wires 18 are drawn out from the drive IC 11, and the drawn wires 18 are electrically connected to the head base 103. Although not shown, the bonding member 16 is drawn out from the drive IC 11 toward the wiring board 6 and is electrically connected to a wiring pattern (not shown) provided on the wiring board 6.

  The wiring substrate 6 is provided with a wiring pattern inside, and electrically connects the FPC 5 and the head base 103 via the wiring pattern. As the wiring board 6, a hard rigid board or a PCB can be exemplified.

  The FPC 5 is electrically connected to the wiring board 6 and electrically connected to the outside through the connector 131. The FPC 5 is formed of a flexible printed wiring board.

  The covering member 129 is formed to extend in the main scanning direction, and is formed across the plurality of drive ICs 11. The covering member 129 is formed over the wiring substrate 6 and the head substrate 3 to bond the head substrate 3 and the wiring substrate 6.

  As shown in FIG. 7, the smoothing layer 116 is provided between the plurality of first pads 104 a and the substrate 7 and is provided to extend in the main scanning direction. The smooth layer 116 has an exposed portion 116 b where the substrate 7 is exposed. The exposed portion 116 b is formed by a rectangular opening in plan view. The second pad 104b is disposed on the exposed portion 116a.

  The second pad 104 b is provided on the exposed portion 116 b of the smooth layer 116, and the smooth layer 116 is provided around the second pad 104 b in plan view. Therefore, the second pad 104b is configured to be lower than the surroundings, and the possibility that the probe needle pressed against the second pad 104b reaches other than on the second pad 104b can be reduced. As a result, it is possible to reduce the possibility that a probe mark is formed in an area other than the second pad 104b.

  In addition, since the smooth layer 16 is provided around the second pad 104b, the step portion 104c is formed by the step 116a of the smooth layer 116 at the boundary between the first pad 104a and the second pad 104b. It is done.

  Therefore, when the probe needle is pressed against the second pad 104b and the electrical inspection is performed, the probe needle does not easily reach the first pad 104a due to the step portion 104c. As a result, the possibility of the probe needle reaching on the first pad 104a can be reduced, and the possibility of the formation of a probe mark on the first pad 104a can be reduced. Therefore, the stability of the electrical connection between the wire 18 and the first pad 104a can be ensured.

  Since the smooth layer 16 is provided around the second pad 104b, the step portion 104d by the step 116a of the smooth layer 116 is formed at the boundary between the individual electrode 19 and the second pad 104b. .

  Therefore, when the probe needle is pressed against the second pad 104b and the electrical inspection is performed, the probe needle is hard to reach the individual electrode 19 by the step portion 104d. As a result, the possibility of the probe needle reaching on the individual electrode 19 can be reduced, and the possibility of the formation of a probe mark on the individual electrode 19 can be reduced. Therefore, the possibility of breakage of the individual electrodes 19 can be reduced.

Third Embodiment
The thermal head X3 will be described with reference to FIG. The thermal head X3 is different from the thermal head X1 in the shape of the pad 204, and the other configuration is the same, so the description will be omitted.

  The pad 204 has a first pad 204a, a second pad 204b, and a neck portion 204e. The first pad 204 a is formed for wire bonding, and the second pad 204 b is provided for electrical inspection. The narrow portion 204e is provided at the boundary between the first pad 204a and the second pad 204b, and is provided at a part of the first pad 204a and a part of the second pad 204b.

  In plan view, a constricted portion 204e is provided at the boundary between the first pad 204a and the second pad 204b. Therefore, when wire bonding is performed, the position of the first pad 204a can be recognized by using the constricted portion 204e of the pad 204 as a mark, and positional deviation of the wire 18 (see FIG. 2) can be suppressed. That is, the constricted portion 204e can be used as a marker at the time of wire bonding.

  In addition, the constricted portion 204 e is formed on the step 16 a of the smooth layer 16. Thereby, the contact area between the step 16 a and the pad 4 can be reduced. As a result, the stress generated between the step 16 a and the pad 4 can be reduced, and the possibility of the pad 4 peeling off the smooth layer 16 can be reduced.

  The narrow portion 204 e is provided only on one side of the long side of the pad 204. Thus, the first pad 204a and the second pad 204b can be prevented from becoming too small due to the constriction 204e. As a result, the electrical connection between the wire 18 and the first pad 204a can be stabilized.

  As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, A various change is possible unless it deviates from the meaning. For example, although the thermal printer Z1 using the thermal head X1 according to the first embodiment is shown, the present invention is not limited to this, and the thermal heads X2, 3 may be used for the thermal printer Z1.

  For example, although the thin thin film head of the heat generating portion 9 is illustrated by forming the electric resistance layer 15 as a thin film, it is not limited thereto. The present invention may be applied to a thick thick film head of the heat generating portion 9 by forming the electric resistance layer 15 as a thick film after patterning various electrodes. Alternatively, the heating portion 9 may be formed by providing the electrical resistance layer 15 only between the common electrode 17 and the individual electrode 19.

  Further, although the planar head in which the heat generating portion 9 is formed on the substrate 7 is described as an example, the present invention may be applied to an end face head in which the heat generating portion 9 is provided on the end surface of the substrate 7.

  In addition, the heat storage layer 13 may be formed in a region other than below the heat generating portion 9 unless it is formed between the second pad 4 b and the substrate 7.

  The sealing member 12 may be made of the same material as the covering member 29 that covers the drive IC 11. In that case, when the covering member 29 is printed, the covering member 29 and the sealing member 12 may be simultaneously formed by printing also on the area where the sealing member 12 is formed.

X1 to X3 Thermal head Z1 Thermal printer 1 Heat sink 2 Pad 3 Head base 4 Pad 4a 1st pad 4b 2nd pad 4c Stepped portion 6 Wiring board 7 Board 9 Heating portion 11 Drive IC
12 Sealing member 14 Bonding member 16 Smooth layer 18 Wire 23 Bonding member 25 Protective layer 27 Covering layer 31 Connector

Claims (7)

A substrate,
A heat generating portion provided on the substrate;
An electrode provided on the substrate and electrically connected to the heat generating portion;
A pad provided on the substrate and electrically connected to the electrode;
The pad has a first pad for wire bonding and a second pad for inspection disposed at a position different from the first pad,
A smoothing layer is provided between the first pad and the substrate;
The smooth layer has an exposed portion where the substrate is exposed,
The second pad is disposed on the exposed portion,
The thermal head , wherein the smooth layer is provided around the second pad in plan view .   The thermal head according to claim 1, wherein a stepped portion is provided at a boundary portion between the first pad and the second pad. A plurality of the pads are arranged in the main scanning direction,
The smooth layer is provided so as to extend in the main scanning direction, provided between a plurality of the first pads and the substrate, and formed of glass. Thermal head. The thermal head according to claim 3 , wherein a stepped portion is provided at a boundary between the electrode and the second pad. The thermal head according to any one of claims 1 to 4 , wherein a surface roughness of the second pad is rougher than a surface roughness of the first pad. A substrate,
A heat generating portion provided on the substrate;
An electrode provided on the substrate and electrically connected to the heat generating portion;
A pad provided on the substrate and electrically connected to the electrode;
The pad has a first pad for wire bonding and a second pad for inspection disposed at a position different from the first pad,
A smooth layer is provided between the first pad and the substrate, and the smooth layer is the second layer.
Not provided between the gate and the substrate,
In plan view, the pad has a constricted portion at the boundary portion between the second pad and the first pad, Sa Maruheddo. A thermal head according to any one of claims 1 to 6 ;
A transport mechanism for transporting a recording medium onto the heat generating portion;
And a platen roller for pressing the recording medium on the heat generating portion.

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