JP2006289999A - Thermal head and method for manufacturing thermal head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve a significant cost-reduction by improving productivity in a substrate process and handleability in a mounting process. <P>SOLUTION: The thermal head (10) comprises a head chip 20, which has a heating element (24) and an electrode (25) connected to the heating element (24) on one face, and a semiconductor integrated circuit (32) connected to the electrode (25). The thermal head (10) also comprises a wiring substrate (30) joined to the other face of the head chip (20), wherein the semiconductor integrated circuit 32 is installed in the wiring substrate (30). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a thermal head and a thermal head unit used in, for example, a small portable recording apparatus, a fax machine, a ticket and a receipt printing apparatus, and a manufacturing method thereof.

  BACKGROUND ART A thermal head outputs a print signal for selectively heating a predetermined heating element at a predetermined timing, with a head chip having a heating element arranged in a row and electrodes connected to the ceramic chip on a ceramic substrate. An IC chip serving as a driver. FIG. 19 shows an example of a thermal head unit in which such a thermal head is mounted on a heat sink and unitized. This thermal head unit includes a thermal head 101 and a heat radiating plate 102 made of aluminum or the like. The thermal head 101 is obtained by forming an electrode 104 and a heating element 105 on a ceramic substrate 103 and further mounting an IC chip 106. Note that the electrode 104 and an external terminal 107 for external signal input provided separately and the IC chip 106 are connected to each other via a bonding wire 108, and the IC chip 106 and the bonding wire 108 are encapsulated resin. 109 is molded.

  Such a thermal head 101 uses a relatively large ceramic substrate 103 in the substrate process to form the electrode 104, the heating element 105, and the like with a thin film or a thick film. There is a problem of being bad.

  Therefore, in order to improve the productivity in the substrate process, a structure in which the ceramic substrate is reduced to form a composite substrate is also known. That is, as shown in FIG. 20, instead of the ceramic substrate 103, a wiring substrate 103B such as a ceramic substrate 103A and a glass cloth base epoxy resin substrate (hereinafter referred to as a glass epoxy substrate) is used. Is provided on the wiring board 103B.

  However, in this case, although the productivity of the substrate process is improved, since the IC chip 106 must be mounted and wire bonding must be performed after the ceramic substrate 103A and the wiring substrate 103B are bonded to the heat sink 102, handling properties are improved. There is a problem that is significantly reduced.

  Therefore, in view of such circumstances, the present invention improves the productivity of the substrate process, improves the handling process of the mounting process, and can significantly reduce the cost, and the manufacturing thereof. It is an object to provide a method.

  A first aspect of the present invention for solving the above-described problem is a thermal head comprising a head chip having a heating element and an electrode connected to the heating element on one surface, and a semiconductor integrated circuit connected to the electrode. A thermal head comprising a wiring board bonded to the other surface of the head chip, wherein the semiconductor integrated circuit is mounted on the wiring board.

  According to a second aspect of the present invention, there is provided the thermal head according to the first aspect, wherein one end side in the width direction of the head chip protrudes from the wiring board.

  According to a third aspect of the present invention, there is provided the thermal head according to the second aspect, wherein the protruding amount of the head chip from the wiring board is 20% to 70% of the width of the head chip.

  According to a fourth aspect of the present invention, there is provided the thermal head according to the first aspect, wherein the head chip is completely overlapped and bonded onto the wiring board.

  A fifth aspect of the present invention is the thermal head according to the fourth aspect, wherein one end side of the wiring substrate protrudes from one end side in the width direction of the head chip.

  According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the semiconductor integrated circuit is mounted on the wiring board substantially in contact with an end face of the head chip. It is in the thermal head.

  According to a seventh aspect of the present invention, in any one of the first to sixth aspects, the height of the surface of the semiconductor integrated circuit is substantially the same as the height of the surface of the head chip. It is in.

  An eighth aspect of the present invention is the thermal head according to any one of the first to sixth aspects, wherein the height of the surface of the semiconductor integrated circuit is lower than the height of the surface of the head chip.

According to a ninth aspect of the present invention, in any one of the first to eighth aspects, the head chip has a common electrode along a longitudinal direction along an end portion in a width direction opposite to the heating element, The thermal head is characterized in that connection wiring for connecting the common electrode and the wiring for the common electrode provided on the wiring board is provided at a plurality of positions in the longitudinal direction.
According to a tenth aspect of the present invention, in the ninth aspect, a connection wiring for connecting the common electrode provided on the head chip and the common electrode wiring provided on the wiring board is defined by the semiconductor integrated circuit. The thermal head is provided between physical blocks.

  According to an eleventh aspect of the present invention, in the tenth aspect, a connection wiring for connecting a common electrode provided on the head chip and a common electrode wiring provided on the wiring board is defined by the semiconductor integrated circuit. The thermal head is provided for each physical block.

  According to a twelfth aspect of the present invention, in any one of the ninth to eleventh aspects, the connection wiring that connects the common electrode provided on the head chip and the common electrode wiring provided on the wiring board includes: The thermal head is provided with at least one physical block defined by a semiconductor integrated circuit.

  A thirteenth aspect of the present invention is a thermal head unit comprising the thermal head according to any one of the first to twelfth aspects mounted on a support.

  According to a fourteenth aspect of the present invention, in the thirteenth aspect, in the thermal head, the heating element forming portion at one end in the width direction of the head chip protrudes from the wiring board, and the heating element is provided on the support body. An upper step portion to which the forming portion is bonded and a step portion that is recessed deeper than the thickness of the wiring board from the upper step portion are formed, and the step when the heating element forming portion and the upper step portion of the head chip are bonded. The thermal head unit is characterized in that an adhesive layer is provided in a gap formed between the wiring portion and the wiring board.

  According to a fifteenth aspect of the present invention, in the fourteenth aspect, the fifteenth aspect includes an adhesive layer that joins the heating element forming portion and the upper step portion of the head chip, and bonding the heating element forming portion and the upper step portion. In the thermal head unit, the adhesive layer is softer than the adhesive layer later before the adhesive layer is cured.

  According to a sixteenth aspect of the present invention, in the fourteenth or fifteenth aspect, the sixteenth aspect includes an adhesive layer that joins the heating element forming portion and the upper step portion of the head chip, and the adhesive layer is thicker than the adhesive layer. It is in the thermal head unit characterized by the above.

  A seventeenth aspect of the present invention is the thermal head unit according to any one of the fourteenth to sixteenth aspects, wherein at least one recessed groove is provided at the bottom of the stepped portion. .

According to an eighteenth aspect of the present invention, there is provided a semiconductor integrated circuit comprising a ceramic substrate having a heating element on one side and an electrode connected to the heating element, and a wiring board bonded to the other side of the head chip. In the method of manufacturing a thermal head mounted on the wiring board, a step of bonding a plurality of the head chips on a wiring board plate capable of taking a plurality of the wiring boards, and a plurality of the semiconductor integrated circuits Mounting the wiring board plate, wiring the electrode on the head chip and the semiconductor integrated circuit, and dividing the wiring board plate into a plurality of parts. There is a method for manufacturing a thermal head.
According to a nineteenth aspect of the present invention, in the method for manufacturing a thermal head according to the eighteenth aspect, the head chips are arranged in parallel in a plurality of vertical and horizontal rows in one direction on the wiring board plate. is there.

  According to a twentieth aspect of the present invention, in the nineteenth aspect, a part of the head chip is bonded in a direction orthogonal to the one direction.

  According to a twenty-first aspect of the present invention, in any one of the eighteenth to twentieth aspects, the wiring board plate has a long hole penetrating the plate, and an inner peripheral surface of the long hole is the wiring board. A method of manufacturing a thermal head is characterized in that at least one end face is formed.

  According to a twenty-second aspect of the present invention, in the twenty-first aspect, in the wiring board plate, an inner peripheral surface of one of the elongated holes forms at least one end surface of the plurality of wiring boards. It is in the manufacturing method of a thermal head.

  According to a twenty-third aspect of the present invention, in the twenty-first or twenty-second aspect, the head chip is provided so as to straddle a peripheral portion on both sides in the width direction of the long hole and to be bonded to only one of the peripheral portions. It is in the manufacturing method of the thermal head characterized.

  According to a twenty-fourth aspect of the present invention, in the twenty-first or twenty-second aspect, the head chip is provided so that a part of the width direction of the head chip faces the elongated hole. .

  According to a twenty-fifth aspect of the present invention, in the twenty-first or twenty-second aspect, the head chip is provided in a peripheral portion on one side in the width direction of the long hole without facing the long hole. There is a method for manufacturing a head.

  According to a twenty-sixth aspect of the present invention, a head chip having a heating element on one side and an electrode connected to the heating element, and a heating element forming part at one end in the width direction of the head chip project. In the method of manufacturing a thermal head unit, a thermal head unit is formed by holding a thermal head that is bonded to the other surface of the substrate and having a wiring board on which a semiconductor integrated circuit connected to the electrode is mounted on a support. A step of supplying an adhesive layer to the step portion of the support having an upper step portion joined to the heating element forming portion and a step portion recessed from the upper step portion deeper than the thickness of the wiring board; and the adhesive layer A step of placing the wiring board on an adhesive layer provided on the stepped portion on the basis of the bonding between the heating element forming portion and the upper step while being uncured, and then the adhesive layer The In manufacturing method for the thermal head unit characterized by comprising, a step of reduction.

  According to a twenty-seventh aspect of the present invention, a head chip having a heating element on one side and an electrode connected to the heating element, and a heating element forming part at one end in the width direction of the head chip project. In the method of manufacturing a thermal head unit, a thermal head unit is formed by holding a thermal head that is bonded to the other surface of the substrate and having a wiring board on which a semiconductor integrated circuit connected to the electrode is mounted on a support. A support body having an upper step portion to be joined to the heating element forming portion and a step portion recessed from the upper step portion deeper than the thickness of the wiring board, with reference to the joining of the heating element forming portion and the upper step portion. Fixing the wiring board to the stepped portion and placing the wiring board on the stepped portion with a gap, supplying an adhesive into the gap, and then the adhesive layer In manufacturing method for the thermal head unit characterized by comprising the step of curing, the.

  According to the present invention, it is possible to reduce the size of the head chip, improve the productivity of the substrate process, improve the handling property of the mounting process, and achieve a significant cost reduction.

Hereinafter, the present invention will be described in detail based on embodiments.
(One Embodiment of Thermal Head)
FIG. 1 shows a schematic cross-sectional view and a plan view of relevant parts of a thermal head according to an embodiment of the present invention. As shown in FIG. 1A, the thermal head 10 includes a head chip 20 on which a plurality of thin film layers are formed, and a wiring substrate 30 that is overlapped and bonded to the head chip 20.

  The head chip 20 is configured by forming various thin film layers on a ceramic substrate 21. First, a grace layer 22 and an undercoat layer 23 made of a glass-based material having a function of a heat insulating layer are formed on the ceramic substrate 21. The grace layer 22 has a ridge portion 22a having a semicircular cross section at a predetermined distance from one end of the ceramic substrate 21, and a predetermined interval in the longitudinal direction in a region facing the ridge portion 22a. Thus, the heating element 24 is intermittently formed. In addition, electrodes 25 made of a metal such as aluminum are formed so as to contact the left and right ends of each heating element 24 in the drawing. Further, a protective film 28 is formed on the heating element 24.

  Here, each heating element 24 is composed of a pair of heating elements 24a and 24b as shown in FIG. 1 (b), and electrodes 25a and 25b are connected to one end of each of the heating elements 24a and 24b. Yes. The electrode 25a functions as an individual electrode, and is connected to a terminal portion 26 made of, for example, a gold thin film layer at an end portion. The electrode 25b functions as a common electrode and is connected to a common electrode 27 provided at the end of the ceramic substrate 21 opposite to the heating element 24. Furthermore, the other end portions of the heating element 25a and the heating element 25b are connected by a U-shaped electrode 25c.

  On the other hand, the wiring substrate 30 is provided with an IC chip 32 and an external terminal 33 on a substrate 31 such as a glass epoxy substrate. The IC chip 32 serves as a driver that outputs a drive signal for selectively heating each of the heating elements 24 described above. The IC chip 32 is provided for each predetermined physical block of the heating element 24. The external terminal 33 is for inputting an external signal to each IC chip 32. Further, each IC chip 32 is connected to the terminal portion 26 and the external terminal 33 described above by bonding wires 34. The IC chip 32 and the bonding wire 34 are molded with a sealing resin 35.

In the thermal head 10 described above, the head chip 20 and the wiring substrate 30 serving as a support substrate for the head chip 20 are partially overlapped and joined, and the IC chip 32 is mounted on the wiring substrate 30. The width of the head chip 20 (left and right direction in the figure) can be remarkably reduced. Therefore, the number of head chips 20 in the substrate process is increased and the productivity is improved. In addition, since the head chip 20 and the wiring board 30 can be handled in a bonded state, there is an advantage that the handling property in the mounting process of the IC chip 32 is not deteriorated. In this case, as will be described later, if a plurality of head chips 20 are bonded onto a wiring board plate from which a plurality of wiring boards 30 can be cut, and the IC chip 32 is mounted and wire bonding is performed, handling properties are improved. There is an effect that is further remarkably improved.
(Manufacturing process)
Hereinafter, an example of the manufacturing process of the thermal head 10 described above will be described in more detail.

  Since the substrate process is basically the same as the prior art, a detailed description is omitted. However, since the head chip 20 is downsized, the number of head chips 20 that can be manufactured in one process is remarkably increased. Productivity can be improved.

  Next, the mounting process will be described with reference to FIGS. FIG. 2 is a plan view showing an initial stage of the mounting process, and FIG. 3 is a cross-sectional view showing a schematic process of the mounting process.

  First, the plurality of head chips 20 are bonded onto the wiring board plate 41. A long hole 42 is formed corresponding to the bonding position of each head chip 20 on the wiring board plate 41. The long hole 42 has a length longer than the length of the head chip 20 and a width smaller than the protruding length of the head chip 20 from the wiring substrate 30 (indicated by H in FIG. 1A). The end of the head chip 20 on the heating element side is disposed so as to cross the long hole 42 in the width direction, so that the peripheral part of the long hole 42 on the tip side of the head chip 20 and the head chip 20 are not joined. That is, in FIG. 3A, the boundary 43a between the left peripheral edge of the long hole 42 and the head chip 20 is not bonded, and only the boundary 43b between the right peripheral edge and the head chip 20 is bonded. Yes. Accordingly, when the wiring board plate 41 is cut into the wiring board 30 using the long holes 42, the inner peripheral surface 42a on one side in the width direction of the long holes 42 forms one end face of the wiring board 30, and the adjacent long holes An inner peripheral surface 42 b on the other side of 42 forms the other end surface of the wiring board 30.

  By thus forming the long hole 42 and disposing the head chip 20 so as to cross the long hole 42, the head chip 20 can be stably held, and the handling property in the mounting process is greatly improved. In addition, a structure in which one end of the head chip 20 protrudes from the wiring board 30 can be easily formed.

  Here, the joining means of the head chip 20 and the wiring board plate 41 is not particularly limited. For example, after applying an adhesive or an adhesive to a predetermined position of the wiring board plate 41 by screen printing, potting, or the like. It can be performed by superimposing the head chips 20. Moreover, the method of sticking a double-sided tape manually or with a machine is also employable. Preferably, it is preferable to use an adhesive that generates a fixing force immediately.

  Next, in the mounting process, an IC chip 32 is mounted along the head chip 20 as shown in FIG.

  Here, the mounting position of the IC chip 32 is not particularly limited, but it may be mounted away from the head chip 20 as shown in FIG. 4A, or the head as shown in FIG. It may be mounted in close contact with the chip 20. In the case of FIG. 4A, the IC chip 32 can be easily mounted, and in the case of FIG. 4B, the above-described bonding wire 34 can be shortened and the entire thermal head can be reduced in size.

  Next, as shown in FIG. 3C, the IC chip 32 and each terminal are connected by bonding wires 34. Subsequently, as shown in FIG. 3D, the IC chip 32 and the bonding wire 34 are molded with a sealing resin 35. Finally, as shown in FIG. 3E, the wiring board plate 41 is cut at predetermined locations (indicated by the cutting lines 44a and 44b in FIG. 2), whereby the thermal head 10 is obtained.

  Here, the wire bonding, sealing, and cutting steps may be performed using a conventionally known technique. For example, as a cutting method, a method using a rotating blade, a method using push cutting, a method using punching with a die set, a cutting with a router, a cutting with laser processing, a cutting with a water jet, or the like can be used.

  As described above, since the mounting process can be performed in a state where the miniaturized head chip 20 is bonded onto the wiring board plate 41, the productivity is high and the cost is significantly reduced.

  In particular, even if the head chip 20 has a structure in which the head chip 20 protrudes from the wiring board 30 and is joined, the head chip 20 can be stably held by using the long holes 42 as described above, and cutting after mounting is easy. It becomes. For example, when the protrusion amount H of the head chip 20 shown in FIG. 1 from the wiring substrate 30 is 20% or more, preferably 50% or more of the width of the head chip 20, the head chip is long as described above. It is indispensable to hold the hole in a passed state. Note that if the protruding amount exceeds 70%, there is a problem that the bonding strength with the wiring board 30 is insufficient.

  In addition, when the end portion of the head chip 20 protrudes from the wiring substrate 30 as described above, the back surface side of the heating element forming portion of the head chip 20 is in direct contact with the heat radiating plate, as will be described later. Has the advantage of improving.

  In the mounting process described above, the method of arranging the head chips on the wiring board plate is not particularly limited, and a plate having no long holes may be used. For example, as shown in FIG. 5A, the head chips 20 may be arranged in a matrix in the same direction, and as shown in FIG. 5B, the head chips 20 are orthogonal to gaps arranged in one direction. The head chips 20 oriented in the direction may be arranged.

Further, in the case of having a long hole, the method of forming the long hole is not particularly limited. For example, as shown in FIG. 6, a plurality of head chips 20 can be arranged in a row on one long hole 42A. Also good. In this case, there is an advantage that the positioning at the time of disposing the head chip 20 becomes simple and it is possible to cope with head chips having different lengths.
(One Embodiment of Thermal Head Unit)
The thermal head 10 described above is used as a thermal head unit by being held on a support made of a metal such as aluminum and having a function of a heat sink. An example of such a thermal head unit is shown in FIG.

  As shown in FIG. 7 (a), the support 50 protrudes from the wiring substrate 30 of the head chip 20 on the back side of the end portion of the head chip 20 (hereinafter referred to as the heating element forming portion) where the heating element 24 is formed. It has an upper step portion 51 that is in close contact and serves as a head chip support portion, and a step portion 52 that is recessed deeper than the thickness of the wiring substrate 30. The heating element forming portion, which is the protruding portion of the head chip 20, and the upper step portion 51 are firmly fixed by an adhesive layer 53, and an adhesive layer 54 is provided at the bottom of the step portion 52. With such a configuration, the support 50 and the wiring substrate 30 are firmly fixed by the adhesive layer 54, and the support 50 and the head chip 20 are firmly fixed by the adhesive layer 53.

  Here, the thermal head 10 is formed by the adhesive layer 53 based on the contact between the back surface of the heating element forming portion of the head chip 20 and the upper step portion 51 while the adhesive layer 54 at the bottom of the step portion 52 is uncured. After bonding, it is preferable to perform a curing process (heating, standing at room temperature, ultraviolet irradiation, etc.) of the adhesive layer 54. As a result, the warp of the wiring substrate 30 such as the glass epoxy substrate is absorbed by the presence of the adhesive layer 54 in the gap between the wiring substrate 30 and the support 50, and the heating element forming portion of the head chip 20 and the wiring substrate 30 are Both are closely fixed to the support 50.

  In addition, it is preferable to use a relatively soft adhesive for the adhesive layer 54 when uncured, whereby a thermal head unit structure based on the joint surface between the support 50 and the head chip 20 can be easily realized. In other words, the heating element forming portion of the head chip 20 and the upper step portion 51 of the support 50 are joined together with the adhesive layer 54 of the step portion 52 uncured, and the wiring substrate 30 is bonded to the adhesive layer in the step portion 52. If the adhesive layer 54 filled in the gap between the wiring board 30 and the stepped portion 52 is made of a fluid or paste-like relatively soft material, the gap is not uniform. The bonding surface between the head chip 20 and the upper step portion 51 is not affected, and the bonding surface between the head chip 20 and the upper step portion 51 serves as a reference surface. Further, even after the treatment for curing the adhesive layer 54 is performed, the warp of the wiring substrate 30 is absorbed by the adhesive layer 54, and the heating element forming portion of the head chip 20 and the wiring substrate are in close contact with the support 50. Fixed.

  Thus, it is preferable to use the adhesive used as the adhesive layer 54 that is fluid when uncured or has a characteristic of being pasty or soft and sticky. Further, it is effective to provide the adhesive layer 54 thicker than the adhesive layer 53.

  In the case of such a head chip 20, if the heating element forming portion that is a protruding portion from the wiring substrate 30 is joined in a state of floating from the support body 50 that is a radiator, the excess heat of the heating element is supported by the support body. Since it cannot escape through 50, there is an adverse effect on the printing function, but such an adverse effect can be avoided by using the support structure as described above.

  In addition, in the thermal head designed to reduce the cost, a glass epoxy substrate is used as a wiring substrate, but also in this case, by adopting the above-described structure, the stress at the bonding boundary due to the difference in thermal expansion coefficient is relieved, It is possible to absorb the warp of the glass epoxy substrate due to the curing process, obtain a sufficient bonding strength, and avoid the difficulty of assembling work.

  Here, the support body 50 described above is not particularly limited as long as it has a stepped portion 52 with a depth T2 (T2> T1) when the thickness of the wiring board 30 is T1. Further, the shape of the stepped portion 52 is a concave portion so that the adhesive layer 54 can be prevented from flowing out and a circuit formed on the wiring board 30 and a connection wiring between an external drive circuit (not shown) can be stably fixed. For example, as shown in FIG. 7B, a stepped portion 52A having an L-shaped cross section may be used.

  Further, as shown in FIG. 8, a groove 55 is provided at the bottom of the stepped portion 52 to form a relief portion of the adhesive layer 54 so as to further prevent the adhesive layer 54 from flowing out to the surface of the support 50. May be. Of course, the number and shape of the grooves 55 are not limited, and one groove may be provided as shown in FIG. 8 (a), or two or more grooves may be provided as shown in FIG. 8 (b). Furthermore, in addition to a rectangular cross section, a groove having a semicircular cross section may be used.

  The adhesive layer 53 that joins the head chip 20 and the upper stage portion 51 of the support 50 is not particularly limited as long as it can form a tightly adhered state for releasing excess heat from the heating element forming portion. A tape, an adhesive, or an adhesive can be used.

  Further, the method for providing the adhesive layer 54 on the bottom of the stepped portion 52 is not particularly limited. For example, although printing using a metal mask that is durable and effective against a step is suitable, a method of injecting using a dispenser can also be adopted. Further, another material such as a sheet-like pressure-sensitive adhesive can be used as long as it can absorb the warp of the glass epoxy substrate and the difference in thermal expansion coefficient.

The method for mounting the thermal head 10 on the support 50 is not particularly limited. For example, after preparing the adhesive layer 53 and the adhesive layer 54 as described above, the support 50 is set on a jig, and the head chip. The thermal head 10 is placed on the support 50 by matching the outer shape with reference to the 20 heating element forming portion. Further, an alignment mark may be attached to each of the support 50 and the thermal head 10, recognition and positioning may be performed using the alignment mark, and the thermal head may be placed on the support 50. Then, the heating element forming portion of the head chip 20 and the wiring board 30 are simultaneously pressed against the support 50 and firmly adhered, and then a curing process is performed to cure the adhesive layer 54. As another method, after placing the thermal head 10 on the support 50 with reference to the heating element forming portion of the head chip 20, an adhesive is poured between the wiring substrate 30 and the stepped portion 52 of the support 50. Thereafter, it is possible to fix the thermal head 10 and the support 50 in close contact by applying a treatment for curing the adhesive.
(Other embodiment of thermal head)
Although various advantages of the thermal head 10 described above have been described, the head chip 20 and the wiring board 30 are overlapped and bonded, and the IC chip 32 is mounted on the wiring board 30, so that it is compared with the conventional structure. Since the IC chip 32 is disposed at a relatively low position, the height of the sealing resin 35 can be reduced, so that when the sheet is actually mounted on a thermal printer or the like, a conveyance space for the printing sheet is actually obtained. There is an advantage that can be easily secured. That is, as shown in FIG. 9, since the gap between the platen roller 57 disposed opposite to the heating element 24 and the sealing resin 35 becomes large, interference between the printing sheet 58 and the sealing resin 35 is avoided. There is an advantage that

  In order to obtain such an effect, it is preferable to use the IC chip 32 whose height is smaller than the thickness of the head chip 20 as described above. However, the present invention is not limited to this. Even if the height is set to be approximately equal to the thickness of the head chip 20, the same effect can be obtained.

  For example, as shown in FIG. 10A, an IC chip 32A having a height equivalent to the thickness of the head chip 20 may be used. As shown in FIG. The height of the IC chip 32 may be equal to the thickness of the head chip 20 by providing the base portion 36, or a step where the joint portion of the head chip 20 becomes relatively thin as shown in FIG. The wiring board 30 </ b> A having the portion 37 may be used so that the height of the IC chip 32 and the thickness of the head chip 20 are equal. Thus, by making the thickness of the head chip 20 and the height of the IC chip 32 substantially the same, the wire bonding operation is facilitated.

  Further, the bonding state between the head chip 20 and the wiring substrate 30 is not particularly limited. As shown in FIG. 11A, even when the head chip 20 protrudes from the wiring board 30 as in the above-described embodiment, not all the portions provided with the heating elements may protrude, or FIG. As shown in FIG. 11B, the end face of the head chip 20 and the end face of the wiring board 30 may overlap with each other. Furthermore, as shown in FIG. It may be inside the end face. In these cases, although it is disadvantageous in terms of heat dissipation of the heating element forming portion, the mounting is stable, and it is advantageous for miniaturization as much as possible. Further, when the end face of the head chip 20 is retracted from the end face of the wiring substrate 30 as shown in FIG. 11C, there is an advantage that contact breakage of the end of the head chip 20 during manufacturing can be prevented. .

Further, when manufacturing a thermal head having these structures, the long hole 42 as described above may or may not be formed in the wiring board plate 41 on which the head chip 20 is mounted. For this purpose, a long hole 42 is preferably formed. Further, the positional relationship between the long hole 42 and the end of the head chip 20 when the head chip 20 is mounted is not particularly limited, and the end surface of the head chip 20 is within the long hole 42 as shown in FIG. As shown in FIG. 12B, the end surface of the head chip 20 and the inner peripheral surface of the long hole 42 may be flush with each other. Furthermore, FIG. As shown in FIG. 4, the end surface of the head chip 20 may be separated from the long hole 42. In such a case, stabilization when the head chip 20 is mounted can be achieved, and mounting without tilting can be easily realized.
(Wiring structure of thermal head)
In the thermal head as described above, when the head chip 20 is miniaturized, for example, it is necessary to minimize the width of the common electrode 27 shown in FIG. Normally, the common electrode 27 is connected to an external terminal via a common electrode wiring provided on the wiring board 30 at both ends, for example. In this case, the electric resistance of the common electrode 27 is As a result, the current value flowing through each heating element 24 varies. That is, the value of the current flowing through the heating element 24 connected to the central portion away from the grounding position of the common electrode 27 is reduced, the amount of heat generation is reduced, and print density unevenness is caused.

  Therefore, in the thermal head of this embodiment, the width of the common electrode 27 is minimized to minimize the width of the ceramic substrate 21, and the connection between the common electrode 27 and the external terminal is devised as follows. The occurrence of uneven print density between the heating elements 24 is prevented.

  13A is a cross-sectional view of a wiring connection portion between the common electrode 27 of the head chip 20 and the common electrode wiring of the wiring substrate 30, and FIG. 13B is a plan view.

  As shown in these drawings, the wiring substrate 30 is provided with the common electrode wiring 61 up to the region between the IC chips 32, and is provided at the common electrode wiring 61 and the end of the ceramic substrate 21. The common electrode 27 is connected to each other by a bonding wire 63. Each common electrode wiring 61 is grounded via an external terminal (not shown). That is, in this embodiment, the common electrode 27 is connected to the common electrode wiring 61 of the wiring board 30 for each physical block defined by the IC chip 32.

  Accordingly, since the connection between the common electrode 27 and the common electrode wiring 61 of the wiring board 30 is provided for each physical block defined by each IC chip 32, the print density unevenness based on the electric resistance of the common electrode 27 is reduced. Can be reduced. That is, it is possible to reduce variation in the value of the current flowing through each heating element and make the heat generation amount uniform between the heating elements.

  The number of common electrode wires 61 may be determined by the electrical resistance of the common electrode 27, the voltage applied during printing, the number of heating elements connected to the IC chip 32, the electrical resistance of the heating elements, etc. For example, as shown in FIG. 14, it may be provided for every two IC chips 32 or for every three or more IC chips 32.

  Further, a plurality of connections between the common electrode 27 of the ceramic substrate 21 and the common electrode wiring 61 of the wiring substrate 30 are provided in each physical block. That is, in the present embodiment, as shown in FIG. 15, the common electrode wiring 61 </ b> A and the corresponding common electrode wiring 61 </ b> B are provided on the surface of the substantially central portion of the IC chip 32. The electrode wiring 61A, the common electrode wiring 61A, and the common electrode wiring 61B are connected by bonding wires 63A and 63B, respectively, and the other configurations are the same as those of the above-described embodiment. As described above, in addition to the connection between the common electrode 27 and the common electrode wiring between the IC chips 32, the connection between the common electrode 27 and the common electrode wiring 61 </ b> A is provided substantially in the middle of the IC chip 32 in the longitudinal direction. As a result, an imbalance in the amount of current flowing through each heating element can be further suppressed, and printing density unevenness can be further reduced.

In addition, the number of connections between common electrodes in each physical block, the connection position, and the connection method are not particularly limited, and the same effect can be obtained as long as a plurality of physical electrodes are provided for each physical block.
For example, instead of performing connection in each physical block via the common electrode wiring 61A provided on the surface of the IC chip 32, a common electrode wiring 61C provided on the lower side of the IC chip 32 as shown in FIG. Alternatively, it may be performed via the bonding wire 63C. In this case, wire bonding can be easily performed, and the length of the bonding wire can be shortened.

  In addition, as shown in FIG. 17, the common electrode wiring 61D provided on the opposite side of the IC chip 32 from the common electrode 27 and the common electrode 27 may be connected by a bonding wire 63D straddling the IC chip 32. Good. In this case, there is an advantage that processing such as providing a common electrode wiring on the IC chip 32 is unnecessary.

  Further, in the above-described embodiment, the connection between the common electrode and the common electrode wiring is performed by wire bonding. However, the present invention is not limited to this, and is not particularly limited as long as it can be electrically connected.

  18A and 18B are a cross-sectional view and a plan view of a wiring connection portion between a head chip and a wiring board of a thermal head according to another embodiment.

  In the present embodiment, the height of the head chip 20 and the wiring substrate 30 are substantially the same, and a flip-chip type semiconductor integrated circuit 32B is mounted so as to straddle the head chip 20 and the wiring substrate 30.

  The terminal portion 26 on the individual electrode 25a connected to the heating element and the external terminal 33A are connected via pads 71 and bumps 72 on the lower surface of the IC chip 32B. Further, the IC chip 32B is provided with short-circuited pads 73 for common electrode wiring, and these pads 73 are connected to the common electrode 27 and the common electrode on the wiring board 30 through bumps 74, respectively. It is connected to the wiring 61E. By using the flip chip IC chip 32B in this way, connection by wire bonding is not necessary.

  Of course, the common electrode and the common electrode wiring may be connected by wire bonding between the flip-chip type IC chips.

  As described above, by connecting the common electrode of the head chip and the external terminal at a plurality of locations in the arrangement direction of the heating elements, it is possible to reduce printing unevenness while keeping the shape of the thermal head small. There is an effect that can be done.

  As described above, according to the present invention, it is possible to reduce the size of the head chip, improve the productivity of the substrate process, improve the handleability of the mounting process, and greatly reduce the cost. There is an effect that can be done.

It is sectional drawing and the top view of the thermal head which concerns on one Embodiment of this invention. It is a top view explaining the manufacturing process of the thermal head which concerns on one Embodiment of this invention. It is sectional drawing explaining the manufacturing process of the thermal head which concerns on one Embodiment of this invention. It is sectional drawing explaining the modification of the manufacturing process of the thermal head which concerns on one Embodiment of this invention. It is a top view explaining the modification of the manufacturing process of the thermal head which concerns on one Embodiment of this invention. It is a top view explaining the modification of the manufacturing process of the thermal head which concerns on one Embodiment of this invention. It is sectional drawing of the thermal head unit which concerns on one Embodiment of this invention. It is sectional drawing of the thermal head unit which concerns on other embodiment of this invention. It is sectional drawing explaining the effect of one Embodiment of this invention. It is sectional drawing which shows the modification of the thermal head which concerns on one Embodiment of this invention. It is sectional drawing which shows the modification of the thermal head which concerns on one Embodiment of this invention. It is sectional drawing explaining the modification of the manufacturing process of the thermal head which concerns on one Embodiment of this invention. It is sectional drawing and the top view of the wiring connection part between the head chip of the thermal head which concerns on one Embodiment of this invention, and a wiring board. It is a top view which shows the modification of the wiring structure of one Embodiment of this invention. It is sectional drawing of the modification of the wiring connection part between the head chip of the thermal head which concerns on one Embodiment of this invention, and a wiring board. It is a top view of the modification of the wiring connection part between the head chip of the thermal head which concerns on one Embodiment of this invention, and a wiring board. It is sectional drawing of the modification of the wiring connection part between the head chip of the thermal head which concerns on one Embodiment of this invention, and a wiring board. It is sectional drawing and the top view of the wiring connection part between the head chip of the thermal head which concerns on the other form of this invention, and a wiring board. It is sectional drawing of the thermal head which concerns on a prior art. It is sectional drawing of the thermal head which concerns on a prior art.

Claims (7)

  A thermal chip comprising a head chip having a heating element on one side and an electrode connected to the heating element, and a wiring board bonded to the other side of the head chip, and a semiconductor integrated circuit mounted on the wiring board In the head manufacturing method, a step of bonding a plurality of the head chips on a wiring substrate plate capable of taking a plurality of the wiring substrates, and a step of mounting a plurality of the semiconductor integrated circuits on the wiring substrate plate And a method of wiring the electrode on the head chip and the semiconductor integrated circuit, and a step of dividing the wiring board plate into a plurality of parts.   2. The method of manufacturing a thermal head according to claim 1, wherein the head chips are arranged in parallel in a plurality of vertical and horizontal rows in one direction on the wiring board plate.   3. The method of manufacturing a thermal head according to claim 2, wherein a part of the head chip is bonded in a direction orthogonal to the one direction.   4. The thermal head manufacturing method according to claim 1, wherein the wiring board plate has a long hole penetrating the plate, and an inner peripheral surface of the long hole is at least one of the wiring board. A method of manufacturing a thermal head, comprising forming an end face.   5. The thermal head manufacturing method according to claim 4, wherein in the wiring board plate, an inner peripheral surface of one of the elongated holes forms at least one end face of the plurality of wiring boards. Manufacturing method.   6. The thermal head manufacturing method according to claim 4, wherein the head chip is provided so as to straddle a peripheral portion on both sides in the width direction of the elongated hole and to be bonded to only one of the peripheral portions. A manufacturing method of a thermal head.   A thermal chip comprising a head chip having a heating element on one side and an electrode connected to the heating element, and a wiring board bonded to the other side of the head chip, and mounting a semiconductor integrated circuit on the wiring board The thermal head according to claim 1, wherein the wiring board has a long hole through which a part of the other surface of the head chip is exposed.

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