JP2009061625A - Thermal head and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a thermal head which prevents a sealing resin from leaking onto a heat sink and avoids the risk of failures of wire appearance and wire disconnection in the thermal head wherein a head substrate and a printed circuit board are arranged and bonded to be fixed on the heat sink, and a wire bonding part connecting a plurality of discrete electrodes of the head substrate with a plurality of driving elements of the printed circuit board is sealed by the sealing resin, and to obtain its manufacturing method. <P>SOLUTION: In the thermal head and its manufacturing method, after widths in the longitudinal direction of the head substrate and the printed circuit board are set narrower than a width in the same direction of the heat sink, at least an adhesive for the head substrate among the adhesive for the head substrate for bonding fixing the head substrate on the heat sink and an adhesive for the printed circuit board for bonding fixing the printed circuit board on the heat sink is exposed on the heat sink at both ends in the longitudinal direction of a boundary part between the head substrate and the printed circuit board. Both end parts in the longitudinal direction of the sealing resin are positioned on and at least inside the exposed adhesive for the head substrate. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a thermal head mounted on, for example, a thermal transfer printer and a manufacturing method thereof.

The thermal head includes a plurality of heating resistors that generate heat when energized, and performs a printing operation by applying thermal energy generated by the plurality of heating resistors to the print medium. Conventionally, a head substrate having a plurality of heating resistors, a common electrode commonly connected to one end of the plurality of heating resistors, and a plurality of individual electrodes respectively connected to the other ends of the heating resistors, And a printed circuit board having a plurality of driving elements for energizing and controlling a plurality of heating resistors through a plurality of individual electrodes of the head board, and the head board and the printed circuit board are provided for heat dissipation. It is bonded and fixed on the aluminum heat sink. The plurality of individual electrodes on the head substrate and the plurality of drive elements on the printed circuit board are each wire bonded, and the wire bonding portion is sealed with a resin material. As the sealing resin, a resin material whose viscosity is lowered by heating, such as an epoxy resin material, is used in order to fill the wire bonding portion without any gap.
JP 2004-58541 A JP 2004-106293 A JP 2005-280204 A

  In the thermal head having the above structure, it is ideal that both end portions of the sealing resin extending in the longitudinal direction of the head substrate and the printed circuit board (alignment direction of the plurality of heating resistors) fit into the head substrate and the printed circuit board. Is. However, the sealing resin is made of a resin material whose viscosity decreases by heating, and it is difficult to strictly control the amount of the sealing resin, so that it may leak from both ends of the head substrate and the printed circuit board onto the heat sink. It was. And if it leaks on the heat sink, the wire in the wire bonding part will be exposed, and the sealing resin on the heat sink will be placed in a high temperature environment, causing cracks and wire breakage. There was a cause.

  The present invention is based on the above problem awareness, a plurality of heating resistors that generate heat by energization, a common electrode commonly connected to one end of the plurality of heating resistors, and a second end of each heating resistor, respectively. A head substrate having a plurality of connected individual electrodes; a printed circuit board having a plurality of drive elements for controlling energization to a plurality of heating resistors of the head substrate; and bonding the head substrate and the printed circuit board adjacent to each other And a sealing resin for sealing a wire bonding portion connecting a plurality of individual electrodes of the head substrate and a plurality of driving elements of the printed circuit board. It is an object of the present invention to provide a thermal head and a method for manufacturing the same that do not leak upward and do not cause a wire appearance defect and a wire disconnection defect.

  The thermal head of the present invention is a head substrate adhesive for bonding and fixing the head substrate on the heat sink after setting the width in the longitudinal direction of the head substrate and the printed circuit board to be narrower than the width in the same direction of the heat sink. Among the adhesives for the printed circuit board for adhering and fixing the agent and the printed circuit board on the same heat sink, at least the adhesive for the head board at both longitudinal ends of the boundary between the head board and the printed circuit board It is exposed on the heat radiating plate, and both end portions in the longitudinal direction of the sealing resin are positioned on at least the head substrate.

  The method of manufacturing a thermal head according to the present invention includes the step of setting the longitudinal width of the head substrate and the printed circuit board to be narrower than the width of the heat sink in the same direction; A step of adhering and fixing the head substrate on the heat radiating plate in a state where the adhesive is exposed on the heat radiating plate at both longitudinal ends of the boundary between the head substrate and the printed circuit board; A step of bonding and fixing a printed wiring board adjacent to the substrate; a step of wire bonding a plurality of individual electrodes of the head substrate and a plurality of individual electrodes of the printed circuit board; and the wire bonding portion and the exposed head substrate And a step of forming a sealing resin across the adhesive.

  The adhesive for the printed circuit is also preferably exposed on the heat sink at both longitudinal ends of the printed circuit board, and the both ends of the sealing resin are preferably positioned on at least the head substrate.

  In a preferred aspect of the adhesive for a head substrate, a planar core having a longitudinal portion along the longitudinal direction of the head substrate and orthogonally extending portions extending in the lateral direction of the head substrate at both ends of the longitudinal portion. Apply in a letter shape.

  The present invention includes an adhesive for a head substrate for adhering and fixing a head substrate on a heat sink and an adhesive for a head substrate at least of an adhesive for a printed circuit substrate for adhering and fixing a printed circuit board on the same heat sink. Since both ends of the boundary between the two substrates are exposed on the heat sink, and both ends in the longitudinal direction of the sealing resin are positioned on at least the head substrate, at least the end of the sealing resin on the head substrate Can be determined (stopped). That is, since the sealing resin does not leak onto the heat radiating plate, it is possible to obtain a thermal head in which there is no possibility of occurrence of defective wire appearance or broken wire. In the present invention, leakage of the sealing resin is prevented by using an adhesive that adheres and fixes the head substrate (and the printed circuit board) onto the heat sink, so that man-hours and costs are not increased.

  1 and 2 show an example of the structure of a thermal head H1 as an object of the present invention. The thermal head H <b> 1 includes a head substrate 10 and a printed circuit board 30 that are bonded and fixed on the aluminum heat radiating plate 1. The head substrate 10 and the printed circuit board 30 are disposed on the surface 1a of the aluminum heat sink 1 with the one end face contact surfaces 10a and 30a in contact with each other.

  The head substrate 10 includes a convex portion formed on one end of the substrate on a substrate 11 made of alumina or a ceramic material, and a flat portion having a uniform thickness extending from the convex portion to the other end of the substrate. , A plurality of heating resistors 13 formed on the convex portion of the glaze layer 12, and the planar size of each heating resistor 13 covering the surface of each heating resistor 13 ( Insulating barrier layer 14 defining resistance length L and resistance width W), electrode layer 15 energizing a plurality of heating resistors 13, and polishing resistance for protecting insulating barrier layer 14 and electrode layer 15 from contact with a platen or the like A wear protection layer 17 is provided. FIG. 2 is a schematic plan view of the head substrate 10 alone. The plurality of heating resistors 13 are a part of the resistance layer 13 ′ formed on the glaze layer 12 and are arranged at predetermined intervals in the Y direction (the longitudinal direction of the head substrate 10 and the printed circuit board 30). ing.

  The electrode layer 15 is formed on the entire surface of the resistance layer 13 ′ and the insulating barrier layer 14, and then is formed with an open portion 15 c that exposes the surface of the insulating barrier layer 14. The electrode layer 15 includes a common electrode 15a connected to one end in the resistance length direction of all the heating resistors 13 and a plurality of individual electrodes connected to the other end in the resistance length direction of each heating resistor 13 through the open portion 15c. It is separated from the electrode 15b. Each individual electrode 15b is formed with an electrode pad 16 for wire bonding. The electrode layer 15 and the electrode pad 16 are made of, for example, Al.

  The printed circuit board 30 is provided separately from the head substrate 10 and connects a plurality of drive elements 31 that control energization to the plurality of heating resistors 13 and a circuit system including the drive elements 31 to the outside. A pattern land portion (not shown) is provided. The driving element 31 is provided for each heating resistor 13 and is arranged at one end of the printed circuit board 30 on the side in contact with the head substrate 10.

  The electrode pads 16 of the plurality of individual electrodes 15b of the head substrate 10 and the plurality of driving elements 31 of the printed circuit board 30 are connected to the head substrate 10 and the printed circuit board 30, the head substrate adhesive 23 for the head substrate, and the printed circuit board. After being bonded and fixed on the aluminum heat radiating plate 1 through the adhesive 24 for bonding, bonding is performed by the Au bonding wire 33 beyond the boundary 40 between the two substrates. The bonding portion including the individual electrode 15b, the electrode pad 16, the drive element 31, and the Au bonding wire 33 is sealed with a sealing resin 34 made of, for example, an epoxy resin. Each drive element 31 is also connected to the circuit system of the printed circuit board 30 by an Au bonding wire 33.

  The present embodiment is characterized by a structure (procedure) for bonding and fixing the head substrate 10 and the printed circuit board 30 to the aluminum heat sink 1 and a sealing structure by a sealing resin 34 in the thermal head H1 having the above basic structure. . As shown in the middle of FIG. 3, the width R (the length in the Y direction) of the head substrate 10 and the printed circuit board 30 is substantially the same, and is smaller than the width Q (the same) of the aluminum heat sink.

  The head substrate adhesive 23 for bonding and fixing the head substrate 10 to the aluminum heat radiating plate 1 is an adhesive resin having elasticity that absorbs thermal conductivity and thermal strain. For example, alumina beads are mixed with a silicon-based adhesive. It has become. The head substrate adhesive 23 is applied as uniformly as possible to the lower surface of the head substrate 10, thereby improving the heat dissipation of the head substrate 10 and preventing color unevenness. The printed circuit board adhesive 24 for bonding and fixing the printed circuit board 30 on the aluminum heat radiating plate 1 is made of, for example, a silicon-based adhesive.

  FIG. 3 shows an embodiment of the bonding step of the head substrate adhesive 23 and the printed circuit board adhesive 24 and the sealing resin forming step with respect to the aluminum heat sink 1. As shown in the upper part of FIG. 3, the head substrate adhesive 23 applied to the head substrate bonding region of the aluminum radiator plate 1 includes a longitudinal portion 23 a along the longitudinal direction of the head substrate 10, and the longitudinal portion 23 a. Are formed in a U-shape having orthogonally extending portions 23b extending in the short direction of the head substrate 10 at both ends thereof. The length S of the orthogonal extension portion 23b is set to be greater than the length s in the short direction of the head substrate 10 (S> s), and the overall width P of the head substrate adhesive 23 is as follows. It is set larger than the width Q of the head substrate 10. Further, in this embodiment, the head substrate adhesive 23 is at least on the head substrate, that is, on the inner side of the aluminum heat radiating plate 1 due to its shape retention force, and the width P thereof is the width of the aluminum heat radiating plate 1. Slightly smaller than Q. 3 and 4 depict the thicknesses of the head substrate adhesive 23 and the printed circuit board adhesive 24 exaggerated.

On the other hand, the printed circuit board adhesive 24 applied to the printed wiring board bonding region of the aluminum heat sink 1 is applied in a straight line by a width slightly longer than the width in the longitudinal direction of the printed circuit board 30.

  When the head substrate 10 is correctly positioned and bonded onto the symmetrical U-shaped head substrate adhesive 23, the longitudinal portion 23a of the head substrate adhesive 23 spreads on the lower surface of the head substrate 10, The orthogonally extending portion 23 b is exposed on the aluminum heat sink 1 at both ends in the longitudinal direction of the head substrate 10. This exposed portion is referred to as an exposed adhesive 23c for the head substrate. The height of the head substrate exposed adhesive 23 c does not exceed the height (thickness) of the head substrate 10. The exposed adhesive 23c for the head substrate extends outside the boundary 40 between the head substrate 10 and the printed circuit board 30 and extends in a direction perpendicular to the boundary 40 across both substrates.

  On the other hand, the printed circuit board adhesive 24 for bonding the printed circuit board 30 onto the aluminum heat sink 1 spreads on the lower surface of the printed circuit board 30 and extends outside the boundary 40 between the head substrate 10 and the printed circuit board 30. . However, the exposure amount is small as compared with the head substrate exposed adhesive 23c. In this way, the head substrate 10 and the printed circuit board 30 are bonded to the bonding regions of the aluminum heat sink 1 so that the contact surfaces 10a and 30a are in close contact with each other when viewed macroscopically.

  Next, as described above, the electrode pads 16 of the plurality of individual electrodes 15b of the head substrate 10 and the plurality of driving elements 31 of the printed circuit board 30 bonded to the aluminum heat radiating plate 1 are connected to an Au bonding wire according to a conventional method. Bonding is performed by 33. Specifically, for example, by applying ultrasonic vibration to the surface of the electrode pad 16 of each individual electrode 15b to destroy the surface oxide film, and forming an alloy layer of Al and Au on the electrode pad 16, the electrode The pad 16 and the Au bonding wire 33 are connected. Similarly, an electrode pad (not shown) of each drive element 31 and an Au bonding wire 33 are connected.

  Thereafter, the bonding portion between the electrode pad 16 of the individual electrode 15b and the electrode pad of each drive element 31 is sealed with an appropriate amount of sealing resin 34 made of, for example, epoxy resin. Then, both ends in the longitudinal direction of the sealing resin 34 are exposed to the head substrate exposed adhesive 23c (and the printed circuit board exposed adhesive) of the head substrate adhesive 23 as schematically shown in the lower part of FIG. 3 and FIG. It stays on the agent 24) and does not leak onto the aluminum heat sink 1. FIG. 4 shows an ideal end shape of the sealing resin 34 with a solid line, and an example of the shape when the sealing resin 34 leaks onto the head substrate exposed adhesive 23c is shown with a chain line 34 ′. . Thus, even if the sealing resin 34 leaks onto the aluminum heat sink 1, the head substrate exposed adhesive 23 c prevents this, so that the wire appearance is poor, and the head substrate adhesive on the aluminum heat sink 1. It is possible to prevent the occurrence of cracks due to leakage of the wire 23 and the wire breakage due to the occurrence of cracks.

  In the above-described embodiment, the printed circuit board adhesive 24 also protrudes from both sides of the printed circuit board 30. However, the printed circuit adhesive 24 may not protrude. Further, the head substrate adhesive 23 has a U-shape in the illustrated embodiment, but is exposed on the aluminum heat sink 1 at both ends in the longitudinal direction of the boundary 40 between the head substrate 10 and the printed circuit board 30. If it is possible, it does not have to be U-shaped.

  In the above embodiment, the real edge type head substrate 10 is used. However, the present invention is applied to a thermal head using a partial glaze type or full glaze type head substrate, and a thermal head using a silicon head substrate. It can also be applied to the head.

It is sectional drawing which shows the structural example of the thermal head made into the object of this invention. It is a top view which shows the head board | substrate (except an abrasion-resistant protective layer) of FIG. It is a top view which shows the adhesion process with respect to the heat sink of the head board | substrate and printed circuit board of the thermal head by this invention, and the formation process of sealing resin. FIG. 4 is a schematic cross-sectional view taken along line IV-IV in FIG. 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Aluminum heat sink 10 Head substrate 11 Substrate 12 Glaze layer 13 Heating resistor 13 'Resistance layer 14 Insulating barrier layer 15 Electrode layer 15a Common electrode 15b Individual electrode 15c Opening part 16 Electrode pad 17 Wear-resistant protective layer 23 Adhesion for head substrate Agent 23a Longitudinal portion 23b Orthogonal extension 23c Head substrate exposed adhesive 24 Printed substrate adhesive 30 Printed circuit board 31 Drive element 33 Au bonding wire 34 Sealing resin H1 Thermal head

Claims (8)

A head substrate having a plurality of heating resistors that generate heat when energized, a common electrode commonly connected to one end of the plurality of heating resistors, and a plurality of individual electrodes respectively connected to the other end of each heating resistor ;
A printed circuit board comprising a plurality of drive elements for controlling energization to the plurality of heating resistors of the head substrate;
A heat radiating plate for adhering and fixing the head substrate and the printed circuit board adjacent to each other; and a sealing resin for sealing a wire bonding portion connecting the plurality of individual electrodes of the head substrate and the plurality of driving elements of the printed circuit board ;
In the thermal head with
The longitudinal width of the head substrate and the printed circuit board is set to be narrower than the width in the same direction of the heat sink,
Among the adhesive for the head substrate for bonding and fixing the head substrate on the heat sink and the adhesive for the printed circuit board for fixing the printed circuit board on the heat sink, at least the adhesive for the head substrate is: Exposed on the heat sink at both longitudinal ends of the boundary between the head substrate and the printed circuit board,
A thermal head characterized in that both end portions in the longitudinal direction of the sealing resin are positioned on at least the head substrate. 2. The thermal head according to claim 1, wherein the printed circuit adhesive is exposed on the heat sink at both ends in the longitudinal direction of the printed circuit board, and the both ends of the sealing resin are positioned at least on the head substrate. Thermal head. 3. The thermal head according to claim 1, wherein the adhesive for the head substrate includes a longitudinal portion along the longitudinal direction of the head substrate, and orthogonally extending portions extending in the lateral direction of the head substrate at both ends of the longitudinal portion. A thermal head having a planar U-shape. 4. The thermal head according to claim 1, wherein the head substrate adhesive is applied on the heat sink wider than the width of the heat sink. 5. A head substrate having a plurality of heating resistors that generate heat when energized, a common electrode commonly connected to one end of the plurality of heating resistors, and a plurality of individual electrodes respectively connected to the other end of each heating resistor ;
A printed circuit board comprising a plurality of drive elements for controlling energization to the plurality of heating resistors of the head substrate;
A heat radiating plate for adhering and fixing the head substrate and the printed circuit board adjacent to each other; and a sealing resin for sealing a wire bonding portion connecting the plurality of individual electrodes of the head substrate and the plurality of driving elements of the printed circuit board ;
In the manufacturing method of the thermal head provided with
Setting the longitudinal width of the head substrate and the printed circuit board to be narrower than the width of the heat sink in the same direction;
In a state where an adhesive for a head substrate for adhering and fixing the head substrate on the heat sink is exposed on the heat sink at both longitudinal ends of the boundary between the head substrate and the printed circuit board, the heat sink Adhering and fixing the head substrate thereon;
Adhering and fixing a printed wiring board on the heat sink adjacent to the head substrate;
Wire bonding the plurality of individual electrodes of the head substrate and the plurality of individual electrodes of the printed circuit board; and straddling the wire bonding portion and the exposed head substrate adhesive, Forming a stop resin;
A method of manufacturing a thermal head, comprising: 6. The thermal head manufacturing method according to claim 5, wherein the printed circuit adhesive is exposed on the heat sink at both ends in the longitudinal direction of the printed circuit board, and both ends of the sealing resin are at least the head substrate. A manufacturing method of the thermal head located above. 7. The thermal head manufacturing method according to claim 5, wherein the head substrate adhesive extends in a longitudinal direction of the head substrate along a longitudinal direction of the head substrate and in a lateral direction of the head substrate at both end portions of the longitudinal direction portion. The manufacturing method of the thermal head currently apply | coated to the planar U shape which has an orthogonal extension part. 8. The method of manufacturing a thermal head according to claim 5, wherein the head substrate adhesive is applied on the heat sink wider than the width of the heat sink.

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