JPS5814779A - Thermal head for heat-sensitive recording - Google Patents

Abstract

PURPOSE:To maintain the degree of flatness of a substrate for heating elements even when temperature is changed, by a method wherein the adhesion between the substrate for heating elements and a base is accomplished by a curable resin for a central part and by an adhesive for a peripheral part, in a thermal head having a substrate for heating elements and a substrate for a multilayer wiring part separated from each other. CONSTITUTION:A substrate 4 for heating elements having the heating elements, a common electrode, individual electrodes and the like provided thereon and a substrate 5 for multilayer wiring which has conductors for multilayer wiring provided thereon are held by adhering to surface parts 11, 12 of the base 10 for the head. In this case, an adhesive tape is applied to adhering parts 11a of the surface part 11 to which the substrate 4 is adhered, while a curable resin is coated on adhering parts 11b of the surface part 11. Accordingly, the dgree of flatness of the surface of the heating elements is made to conform to the degree of flatness of the adhering surface part 11 of the base 10 for which the degree of flatness is preliminarily secured, and it is unnecessary to add a substrate for compensating for the degree of flatness. In addition, a stopper 14 may be provided for reinforcing the adhering parts 11b.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal recording nozzle, and particularly relates to a substrate forming a heating element and a substrate forming a multilayer wiring part of a semiconductor device for driving the heating element. The present invention relates to an adhesive structure between a heating element substrate and a base of a heat-sensitive recording head, which are separated and integrated and held on one base.

As is well known, the thermal recording method is applied in various fields as a method for obtaining maintenance-free hard copies.

Among these various types of thermal heads, those in which a large number of heating elements are arranged in a row have come to be used very often in facsimile machines, but an important problem with the four seats of this type of head is the low temperature of the head. It's the price.

In a thermal head that has many heating elements arranged in a row,
In order to conveniently drive the heating element, various semiconductor devices (semiconductor devices) are connected in series with the heating element. Currently, ICs such as diodes, thyristors, shifters, registers, latches, and transistors are used as semiconductor devices. In any of these semiconductor devices, multiple wirings are required for terminals other than the terminals connected to the heating element of the semiconductor device.

When using diodes in semiconductor devices, one end of the diode is commonly connected in the case of the so-called common diode method. It becomes necessary.

In order to reduce the price of various thermal heads such as
Although approaches can be taken from various viewpoints, the heating element is formed using conventional thin film formation technology. In the case of a so-called thin-film thermal head, a heating element forming substrate and a multilayer wiring substrate are formed separately, and when semiconductor devices are mounted, these two substrates are held together on a thermal head base. It has been proposed to reduce the cost of forming a heating element substrate to less than μ.

In a thermal head for heat-sensitive recording having such a configuration,
The cost of forming the multilayer wiring board and the cost of maintaining the heating element board and the multilayer wiring board together are two factors that increase the cost.

However, in contrast to the method in which the heating element and the multilayer wiring section are formed on one substrate, in the above method, the heating element substrate size is less than A, so the heating element formation process, that is, the thin film formation of the heating element and electrode , The effect of doubling the capacity of the manufacturing equipment for pattern formation of the heating element and electrodes, and formation of the wear-resistant layer &:J: , The cost reduction effect for the head as a whole is extremely large.

The present invention provides a heating element substrate and a base that rationally process iIn generated when bonding the two substrates to a base after separating and forming the heating element substrate and multilayer wiring substrate. The present invention relates to the adhesive structure of the present invention.

In order to facilitate understanding of the present invention, problems with conventional thermal heads for heat-sensitive recording will be explained below with reference to the drawings.

FIG. 1 is a wiring diagram of a heating element and a diode when a separate diode is used as a semiconductor device, where 1 is a heating element, 2 is a diode, and 3 is a multilayer wiring section.

FIG. 2 shows an example of the structure of the head corresponding to FIG. 1.

In FIG. 2, 4 represents the heating element 1 and the common electrode 6a.

The substrate 6 on which the individual electrodes 6b are formed is a multilayer wiring substrate, and on the multilayer wiring substrate 5, a multilayer wiring conductor 9 is formed. Generally, a wear-resistant layer is formed on the top of the heating element 1, but this wear-resistant layer is omitted in FIG. 2a is a semiconductor chip on which a plurality of diodes (five in the case of FIG. 2) are formed, and each diode is supported by flexible electrically insulating films 7a and 7b. Straight and L-shaped leads sa, sb
is led.

A method of attaching leads to the semiconductor chip 2a to the leads sa and sb held by the above-mentioned flexible films 7a and 7b.'
The ceremony is carried out by a method known as the film carrier method. A thermal head corresponding to FIG. 1 is formed by connecting the other ends of the straight and L-shaped leads connected to the semiconductor chip to the individual electrodes 6b of the heating element and the multilayer wiring conductor 9, respectively.

However, this connection is made after the heating element substrate 4 and the multilayer wiring substrate 6 are integrated into the head base 1o. For the heating element substrate, an alumina substrate or the like with a glass layer formed on the surface is suitable due to the properties required of the heating element, and for the multilayer wiring board 6, a printed circuit board or the like, which is cheaper than the alumina substrate, is used. . Head base 1o
For this purpose, a metal plate (iron plate, aluminum plate, etc.) is used in consideration of the ease of mounting the head on the device.

In order to manufacture the head shown in Fig. 2, when bonding the heating element substrate 4 and the head base 1o, the heating element forming surface (actually the surface of the 1ffiJ wear layer) on the heating element substrate should be made as perfectly flat as possible. It is surprisingly difficult to meet this requirement (this requirement is necessary for complete contact between the recording paper and the heating element).

A configuration conventionally used for this purpose is shown in FIG.

In FIG. 3, 13 is the same alumina substrate as the heating element substrate 4. As shown in FIG. 3, if the heating element substrate 4 and the flatness compensation substrate 13 are adhered to the upper and lower surfaces of the head base 10,
Regardless of the difference in thermal expansion coefficient between the head base 1o and the heating element substrate 4, the flatness of the surface of the wear-resistant layer due to temperature rise during adhesion or during use of the head can be maintained within a range that does not affect thermal recording.ぢ1; Do it.

However, this configuration has problems such as the fact that it is troublesome to add the flatness compensation substrate 13 during actual head manufacture, or the presence of the flatness compensation substrate 13 becomes an obstacle when fixing the head. There are disadvantages0.In addition, by using a softer material than the heating element substrate for the multilayer wiring board, such as a printed circuit board, the influence on the flatness of the heating element can be reduced0. ” In a thermal head that is divided into a heating element board and a multilayer wiring board, which are like two, the effects on the leads of the semiconductor element connected between these two boards, or the lead connection part (disconnection, lead deviation, etc.) is small, and
The present invention provides a thermal head for thermosensitive recording having a structure in which a heating element base and a head base are bonded together to ensure the flatness of a heating element substrate.

Embodiments of the present invention will be described below with reference to the drawings.

In the following description, the same parts as those of the follower's thermal head for heat-sensitive recording are given the same numbers.

FIG. 4 shows a heating element board according to an embodiment of the present invention, and similarly to the above example, 4 is a heating element board, 5 is a base for multilayer wiring, and 1o is a head base. However, on the heating element substrate 4 and the multilayer wiring board, if the semiconductor device connected to the heating element is a diode, or in the case of other semiconductor devices as shown in FIG. Although conductor patterns suitable for the device are formed, these conductor patterns are not directly related to the present invention and are therefore omitted in FIG.

In FIG. 4, the heating element substrate 4 and the multilayer wiring substrate 6 are adhesively held on surfaces 11 and 12 of the head base 1o. In this embodiment, this adhesive, especially the adhesive part 11, is
As shown in the figure, it is divided into two parts 11a and 11b, and different adhesives are applied to these parts. That is, an adhesive (non-hardening type) tape is applied to the adhesive part 11a, a curable resin is applied to the adhesive part 11b, and the heating element substrate 4 is held in contact with electricity. With such an adhesive structure, the flatness of the heating element surface can be reduced by the adhesive part 9 of the head base whose flatness has been ensured in advance.
: The flatness can be made to conform to the flatness of 11, and the substrate 13 for ensuring the flatness as shown in the conventional example shown in FIG.

The area of the adhesive part 11b of the heating element substrate is determined by heat treatment during adhesion between the heating element base 4 and the head base 1o (particularly when adhering with a curable resin), or by heat treatment during thermal recording between the heating element substrate and the head. The size should be such that warping of the flatness of the heating element due to temperature changes such as a rise in the temperature of the base will not be a problem.

Due to these temperature changes, the difference in elongation between the heating element substrate and the base is the adhesive part 11! In the portion L, there is a deviation in the xy plane in FIG. 4, but this deviation is absorbed by the adhesive, and the flatness of the heat generating element is kept within a range that does not cause problems in recording.

On the other hand, when bonding the multilayer wiring board 5, even if the entire bonding surface 12 is bonded with a curable resin by using a printed circuit board, the effect on the flatness of the heating element is minimal. . If a material similar to that of the heating element substrate is used as the multilayer wiring board 5, the effect on flatness can be avoided by adhesion similar to that of the heating element substrate in Fig. 4. .

In a head with an adhesive structure as shown in FIG. 4, the strength of the adhesive part 11b is determined against shear stress in the y direction or xr plane that is generated on the adhesive surface due to contact abrasion with paper during thermal recording. It is effective to provide the stopper 14 for reinforcement. The shape of this stopper 14 can be configured in various shapes depending on the actual shape of the head.

In this way, there are various deformations in the actual head, but
The heating element board and head base are connected using a hardening adhesive (e.g. Ebogishi type) in the center of the heating element board and an adhesive adhesive around it (
The basic idea of the present invention is to make the flatness of the heating element equal to the flatness of the base by adhering it to the head base using an adhesive (usually called adhesive tape), and to prevent this flatness from changing with temperature. be.

As explained above, the present invention separates the heating element substrate and the multilayer wiring board, and integrates the heating element and the heating element driving device into one unit. This provides a very useful bonding structure between the heating element substrate and the head base, and also has the following effects.

]) Freedom of Selection of Head Base According to the present invention, the necessary flatness can be ensured even when there is a large difference in the coefficient of thermal expansion between the heating element substrate and the head base. That is, an inexpensive and lightweight substrate such as AI can be used as the head base, which helps reduce the weight of the entire head.

In contrast, in the conventional configuration shown in FIG.
If a J base is used, the substrate may peel off due to insufficient strength of the adhesive.

11) Rationalization of the head manufacturing process In actual thermal heads, various heat dissipating fins and the like are often attached as a measure against the rise in head temperature during thermal recording.

In this case, if the heating element substrate and the multilayer wiring substrate are separated and these two substrates are directly bonded to a head base that also serves as a heat dissipation effect, it becomes difficult to design a device for connecting leads of a semiconductor device.

In contrast, in the present invention, -1=11, the device design described above is facilitated by attaching various heat dissipating fins after performing the adhesion shown in FIG. 4 and the lead connection for mounting the semiconductor device on the head. Become. Of course, this problem does not need to be considered in the case of a thermal head in which the heating element board and the multilayer wiring board are not separated, but the separation is carried out for the purpose of reducing the manufacturing cost of the heating element board. It is well understood that the present invention is useful in a head configured as shown in FIG.

It has also been experimentally confirmed that the reliability of the lead connection of a semiconductor device in a head having an adhesive structure as shown in FIG. 4 is almost the same as that in the case shown in FIG.

[Brief explanation of drawings]

FIG. 1 is a basic circuit diagram of a thermal head for heat-sensitive recording, FIG. 2 is a diagram showing the actual structure of the thermal head, FIG. 3 is a perspective view showing the structure of a conventional thermal head for heat-sensitive recording, and FIG. FIG. 4 is an exploded perspective view of a thermal head for heat-sensitive recording according to an embodiment of the present invention. 4... Heating element board, 6... Base for multilayer wiring, 1°...° Head base, 11.11 &, 11
b, 12'...Adhesive part.

Claims (2)

[Claims] (1) In a thermal head for thermosensitive recording in which a heating element substrate on which a heating resistor is formed and a multilayer wiring board on which a multilayer wiring portion of a semiconductor device is formed are fixed to a head base, the heating element A thermal head for heat-sensitive recording, characterized in that a substrate is adhered to the head base using a plurality of adhesives of different types. (2) The thermal head for heat-sensitive recording according to claim 1, characterized in that a curable adhesive and a non-curable adhesive are used as the adhesive.