JPS63179764A - Thermal recording head - Google Patents

Abstract

PURPOSE:To achieve miniaturization and to enhance the reliability of connection at low cost, by a method wherein the individual electrode on the first substrate and IC on the second substrate as well as IC on the second substrate and signal electrode wiring are respectively connected by wire bonding, and IC and the signal electrode wiring are provided on the same second substrate. CONSTITUTION:It is extremely important that electrode wiring 5 to a heat generating part 2, that is, the lead part 5a and the pad 11 of IC 7 are connected by wire bonding using a wire 14 and the terminal of the signal electrode wiring 8 on the side of IC, that is, the lead part 12 thereof and the pad 11 of IC 7 are connected by wire bonding using a wire 15. Because of such a structure that IC 7 and the signal electrode wiring 8 are together provided on the same substrate 9, the substrate, that is, a head can be miniaturized and, when only the alignment between both substrates 6, 9 is performed, connection can be performed automatically by wire bonding with good workability and good reliability. Since the lead part 5a can be allowed to approach a platen roller 17, a substrate size is further reduced to make it possible to still more attain miniaturization and cost reduction.

Description

[Detailed description of the invention] B. Industrial application fields The present invention relates to a thermal recording head.

Conventional technology A thermal recording head called a thermal head (hereinafter referred to as
Simply abbreviated as head. ) is in contact with a recording medium such as recording paper or thermal paper, either directly or via an ink film, and the heating part is selectively heated in a dot shape by an electric signal for recording. It is configured to be able to record images and the like on a recording medium.

In conventional heads, a heat generating layer is generally provided on a substrate, and a large number of opposing electrodes are formed on this layer to form a heat generating section. ) to give a signal corresponding to the desired image pattern.

However, when mounting an IC "externally", the IC requires its own placement space, and there are problems with the reliability and workability of the electrical connection to the heat generating part (usually connected by lead wire). .

Therefore, a head in which a heat generating part and an IC are provided on a common support has been proposed. For example, a heating element, a common electrode, an individual electrode, and a signal electrode are provided on an alumina substrate, and an individual electrode, a signal electrode, and an IC are provided on a tape carrier.・The signal electrodes are inner lead bonded (soldered), and the individual electrodes and signal electrodes on the tape carrier and the individual electrodes and signal electrodes on the alumina substrate are outer lead bonded (soldered) on a common heat sink. ) and are individually connected to each other.

However, in such a tape carrier system, although the size of the head is reduced, the cost of the tape carrier is high, which is disadvantageous.

As a method that is considered to be superior to this tape carrier method, a heating element, a common electrode, individual electrodes, and a signal line for IC1IC are each provided on an alumina substrate, and for example, the individual electrodes, signal lines, and IC are wire bonded. In some cases, a signal electrode provided on another flexible substrate and a signal line on an alumina substrate are connected by crimping or soldering. In this case, the end of the flexible substrate (that is, the end of the signal electrode) is overlapped with the end of the substrate on the IC side (that is, the end of the signal line to the IC), and is crimped and fixed. However, this is constructed on a common heat sink. A large number of the signal electrodes are provided on the flexible substrate, and connections between these signal electrodes are realized by a multilayer wiring structure.

However, in such heads, when trying to reduce costs by downsizing the head and making the machine in which the head is smaller and lighter, the area occupied by the IC section on the board may be reduced due to the pressure bonding of the flexible board for the signal electrodes. This is disadvantageous in that it tends to increase. Moreover, in the case of the flip-chip method, bump plating of an appropriate size must be applied to the IC pad.
As a result, it is not possible to properly align the patterns to be bonded in a short time, or the pinch or width of the same pattern cannot be made very narrow (therefore, the wiring density cannot be increased). There are limits to reducing the area.

Note that Japanese Patent Application Laid-Open No. 61-280953 discloses a method in which an alumina substrate on which a heating element, a common electrode, and an individual electrode are provided, and a flexible substrate on which an IC and a signal electrode are respectively fixed on a common heat sink. , individual electrodes and IC on alumina substrate,
A head is shown in which an IC and a signal electrode on a flexible substrate are connected by wire bonding. Even in this case, since the signal electrodes are provided on a flexible substrate separate from the IC, the bonding position will shift if the positional accuracy is not improved when fixing the IC and flexible substrate on the heat sink. However, such precise fixation is generally difficult. Furthermore, since positional accuracy between the alumina substrate, IC, and flexible substrate must be achieved, bonding accuracy is likely to be insufficient.

OBJECTS OF THE INVENTION An object of the present invention is to provide a thermal recording head that is small in size, low in cost, and has good connection reliability.

24 Structure of the Invention That is, the present invention provides a first base body provided with a heat generating part and individual electrode wiring to the heat generating part, an integrated circuit device for operating the heat generating part, and a signal electrode to the integrated circuit device. and a second base body provided with wiring on a common support, the connection between the individual electrode wiring and the pad of the integrated circuit device, and the connection between the signal electrode wiring and the pad of the integrated circuit device. These are related to thermal recording heads in which wire bonding is used.

E, Example The present invention will be explained in detail below.

1 to 4 show an embodiment in which the present invention is applied to a line type head. According to this head 1,
An alumina substrate 6 on which the individual heating elements 3 constituting the heating section 2, a common electrode 4, and individual electrode wiring 5 to the heating section are provided, and a flexible printed circuit board 9 on which the IC chip 7 and the signal electrode wiring 8 are provided. are fixed on an aluminum heat sink 10 which is a common support. in this case,
A glaze layer exists directly below the heat generating part 2, but this is not shown. Further, in the substrate 9 on which the IC 7 is mounted, the number of bonding pads 11 of the IC 7 is shown in a simplified diagram (this also applies to the wiring 5 of the substrate 6). Also, only one IC7 is shown for ease of understanding.

The signal electrode wiring 8 is formed between the cover film 9a and the base film 9b of the substrate 9, and its end portion 12 is led out to the surface of the substrate 9 via a through hole, and a terminal is provided at one end of the substrate 9. 8a.

Although not shown in the drawings, the signal electrode wirings 8 are separated from each other or connected to each other by a multilayer wiring structure. Board 9
A part of the board 6 is superimposed under the substrate 6, and an adhesive 13 is applied thereto.
(the shaded area in Figure 3) is applied and fixed with adhesive.

Note that the back surface of the substrate 9 is fixed to the heat sink 10 using double-sided tape or adhesive.

In the above, the end portion 5a (that is, the lead portion) of the individual electrode wiring 5 to the heat generating portion 2 and the pad 11 of the IC 7 are wire-bonded by the wire 14, and the IC
The end portion 12 (i.e., lead portion) of the side signal electrode wiring 8 and the I
It is extremely important that the pad 11 of C7 is wire-bonded with the wire 15. This will be explained in detail along with the head work process.

First, as clearly shown in FIG. 3, a substrate 6 provided with the above-mentioned heat generating part 2 and both electrode wirings 4.5 is created by a known thin film or metallizing technique, and on the other hand, the signal electrode wiring 8.
A substrate 9 is prepared.

Then, with the IC 7 mounted on the substrate 9, an adhesive 13 is applied, and both substrates 6 and 9 are bonded together on the heat sink 10 along their edges. Next, between the individual electrodes on the substrate 6! 5
and the pad 11 of the IC 7 on the substrate 9, and further between the pad 11 of the IC 7 on the substrate 9.
The upper signal electrode wiring 8 and the pad 11 of the IC 7 are connected by wires 14 and 15, respectively, as described above. Next, the wire bonding part and the IC part are sealed with resin as shown by the dashed line 16 in FIG. 2, and then bonded to the heat sink 10. In this example, as shown in FIG. 1, since the lead position (or number) of the individual electrode wiring 5 and the pad position (or number) of the IC 7 are aligned in the pad row direction, the lead is connected to the IC 7.
They are placed close together over the length of the .

As mentioned above, the head of this embodiment does not use the conventional film carrier system, but instead uses the individual electrode wiring 5, IC 7, and
Since the C7 and the signal electrode wiring 8 are directly connected to each other by wire bonding, and the IC 7 and the signal electrode wiring 8 are both provided on the same substrate 9, the substrate (and by extension the head)
In addition to being able to miniaturize the substrates 6 to 9, as long as the two substrates 6 to 9 are aligned, they can be automatically connected by wire bonding with good workability and reliability.

Further, as shown in FIG. 4, a recording paper and an ink film (indicated together as a dashed line 18 in the figure) are placed between the platen roller 17 and the head 1 at the heat generating section 2.
When performing recording by sandwiching the printed circuit board 9 at the positions shown in FIG. Advantageously, it is approximately at the same level as the lower surface of. In other words, the protrusion on board 6 is IC7.
However, since it is only the lift of the wire 14, even if the distance between the platen roller 17 and the lead part 5a is reduced when the head is mounted on the machine, the sealing resin 16 will not be a problem and the wire 18 can be removed. It can be transported well. On the other hand, when the IC 7 is mounted on, for example, an alumina substrate 6 as shown in FIG. In addition to the elevation of the IC 7, the height of the IC 7 is added, and therefore the height of the sealing resin 16 itself becomes larger than that shown in FIG. Therefore, it is necessary to position the sealing resin 16 quite far from the platen roller 17 (in other words, it is necessary to increase the distance between the lead part 5a and the heat generating part 2).
If platen rollers 17 of the same shape are used, the size of the head will be larger than that shown in FIG.

Conversely, the head of this embodiment shown in FIG.
Since a can be brought closer to the platen roller 17, the substrate size can be further reduced to achieve further miniaturization and cost reduction.

6 to 8 show other embodiments in which the present invention is applied to a line system.

In the case of the head 21 of this example, as shown in FIG.
When the pad numbers (#1 to #64) of the pads 7 are not aligned with the lead numbers (#1 to #64) of the lead portion 5a as in the example of FIG. The pads are arranged and bonded with wires 14 in correspondence with the pad numbers. Therefore, as clearly shown in FIG. 8, a plurality of bonding wires 14 (two in the example shown) are placed vertically in the same position between the individual electrode wiring 5 and the pad 11 of the IC 7. Become. Even in this case, the IC7 is connected to the board 6
Since there is no upward protrusion, the height of the sealing resin 16 is lower than that shown in FIG. 5.

9 and 10 show an embodiment in which the present invention is applied to a serial type head.

In this head 31, a glaze layer 30 of silicon oxide, for example, is provided linearly on an insulating substrate (for example, a ceramic substrate made of alumina, etc.) 36 fixed to an aluminum heat sink 40, and a glaze layer 30 of silicon oxide, for example, is provided in a straight line, and 24 glaze layers are usually formed across the glaze layer 30. A heating element (for example, tantalum nitride) 33 is arranged. One side of each of these heating elements 33 is connected to a common electrode 34 made of, for example, aluminum or gold, and the other side is connected to an individual electrode 35 of, for example, aluminum or gold, so that a signal to be sent to the heating part 32 is sent from the individual electrode 35. I have to. The common electrode 34 and the individual electrodes 35 are bonded to the pads 11 of the IC 7 mounted on the flexible substrate 39 by wires 14 near a heat dissipation section 40a provided at the end of the heat dissipation plate 40. This flexible substrate 39 is made up of a cover film 39a and a base film 39b, and similarly to the substrate 9 of FIG.
is bonded to the pad 11 of the IC board by a wire 15, and the other end (not shown) is led out as a terminal similarly to 8a in FIG.

Since such a serial type head 31 is constructed based on the present invention, it is different from the conventional product in which the signal electrode wiring 38 is simply used as a lead and is thermocompressed onto the individual electrode wiring 35 (however, the IC is externally attached). Compared to the above, the area occupied by the IC section is reduced, mounting and connection thereof are easier, and bonding reliability is improved.

Although the present invention has been illustrated above, the above-mentioned example can be further modified based on the technical idea of the present invention.

For example, the arrangement, shape, layer structure, material, etc. of the heat generating part and the rc part may be changed in various ways. The material, shape, etc. of each board used may be changed. For example, as the board 9 on which the IC is mounted, in addition to a flexible printed circuit board, a normal hybrid board, a glass epoxy board, etc. can also be used. Also,
Of course, the present invention can also be applied to a device that directly records on thermal paper.

As described above, the present invention provides wires between the individual electrodes on the first substrate and the IC on the second substrate, and between the IC on the second substrate and the signal electrode wiring. Since they are connected to each other by bonding, and the IC and signal electrode wiring are provided on the same second base, the head itself can be made smaller and lower in cost.
As long as the first base body and the second base body are aligned, it is possible to automatically connect the first base body and the second base body with good workability (and high reliability) by wire bonding.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which FIG. 1 is a plan view of a part of a line-type thermal recording head, FIG. 2 is a sectional view taken along the line ■-■ in FIG. 1, and FIG. Figure 1 is an exploded perspective view of Figure 1, Figure 4 is a sectional view of the main part when the head is in use, Figure 5 is a sectional view of the main part when the head is used for comparison, and Figure 6 is a part of another line-type thermal recording head. Fig. 7 is a schematic diagram showing the correspondence between leads and IC pads, Fig. 8 is a sectional view taken along the line ■-■ in Fig. 6, and Fig. 9 is a plan view of a portion of a serial type thermal recording head. FIG. 10 is a sectional view taken along the line X--X in FIG. 9. In addition, in the symbols shown in the drawings, 1.21.31...Head 2.32...Heating part 3.33...Heating element 4.34...Common electrode 5.35... ...Individual electrode wiring 5a ...Lead part 6.9.36.39 ...Substrate 7 ...IC chip 8.38 ...Signal electrode wiring 10.40 ...Heat sink (Support) 11
...Pad 12.42 ...End portion 13 ...Adhesive 14.15 ...Wire 16 ...Sealing resin 17 ...Platen roller 18
...Recording paper and ink film. Agent Patent attorney Aisaka Youngest brother 1 N Figure 2 5a 8 j ″”5 'Ja
? :51 (J Figure 7]] 7 8 Figure 9 Figure 10

Claims (1)

[Claims] 1. A first base body provided with a heat generating part and individual electrode wiring to the heat generating part, and a second base body provided with an integrated circuit device for operating the heat generating part and signal electrode wiring to this integrated circuit device. on a common support, and the connection between the individual electrode wiring and the pad of the integrated circuit device and the connection between the signal electrode wiring and the pad of the integrated circuit device are performed by wire bonding, respectively. Thermal recording head.