JPS625859A - Manufacture of thermal head - Google Patents

Abstract

PURPOSE:To provide a thermal head in which resistance of individual heating resistors is extremely stable, by a method wherein an insulating substrate is so bent that a heating resistor row is located on a substantially flat top surface, the substrate is mounted on and fixed to a heat-releasing base, and driving elements are mounted on the substrate at predetermined positions. CONSTITUTION:The heating resistor substrate 39 is so bent that the other side thereof is disposed on the inside and a row of heating resistors 33 are located on the substantially flat top surface. In this case, a part 413 to be bent of a metallic sheet 30 is removed by etching or the like to make the part flexible, followed by bending, whereby a wiring 341 is prevented from being opened due to cracking or the like. This process also prevents the row of the heating resistors 33 from being distorted, so that the uniform resistance of the resistors 3 can be maintained. The substrate 39 is mounted on and adhered to the metallic member 41 so that the row of the resistors 33 is located on the substantially flat top surface 411 of the member 41 while parts corresponding to the wiring parts 341, 342 are located at the bent pats 413 of the member 41.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a thermal head and a method for manufacturing the same, and particularly to a heating resistor portion thereof.

[Technical background of the invention and its problems] It is well known that thermal heads are used in facsimiles and other recording devices. This thermal head is required to be able to accurately and quickly record characters and images, and the recording apparatus in which this thermal head is assembled is also required to be compact.

Conventionally, such a miniaturized thermal head was developed in Japanese Patent Application Laid-open No. 5
It was discovered in Japanese Patent No. 7-131576. In this publication, 1. a resistive heating element divided into required patterns is formed on a synthetic resin film by photo-etching or other methods, a wiring section is provided on this resistive heating element, and the center of the resistive heating element is connected from a straight apex to both directions. A thermal head formed on a roof-like sloped surface is shown.

By the way, when the present inventor experimented with a prototype of the thermal head disclosed in this publication, it was found that it was not suitable for practical use due to the following points. That is, significant problems were presented in terms of uniformity of the resistance value of the heating resistor and its lifespan. In other words, the thermal head disclosed in this publication requires bending at the resistance portion. This causes distortion in the resistance value of the heat generating resistor, resulting in a large change in the resistance value of the heat generating resistor. The present inventor attempted to control the distortion in the resistance value of this heating resistor, but since the range of values in which this distortion changes is large,
It was impossible to keep it within a practical range. In addition, in severe cases, cracks occurred in the resistor section, and wire breakage occurred in the resistor section.

In addition, in this thermal head, since the resistance portion was straightened to form a slope, the life of the heating element during use of the thermal head was significantly shortened, resulting in a problem of lack of reliability.

[Purpose of the invention]

The present invention has been made in view of the problems of the prior art described above, and an object of the present invention is to provide a thermal head in which the resistance value of each heating resistor is extremely stable, and a method for manufacturing the same.

[Summary of the invention]

In order to achieve the above-mentioned object, a thermal spatula 1-
And its manufacturing method involves coating a heat-resistant organic resin on the surface of a metal plate to form an insulating substrate, forming a heating resistor array and a wiring section on this resin, and then applying the heating resistor array to the insulating substrate. The insulating substrate is bent and placed and fixed on a heat-dissipating substrate so that it is located on a substantially flat top surface, and a driving element is placed at a predetermined position on this insulating substrate.

This prevents undesired resistance value distortion from occurring in the heating resistor, making it possible to perform extremely stable printing.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 3.

In FIG. 1, the metal plate (30) has a thickness of approximately 0.1 mm, for example.
A varnish-like heat-resistant resin such as UFILEX-5 (trade name: Super heat-resistant polyimide, manufactured by Bukosan Co., Ltd.) is applied to the surface of an iron plate of mm in diameter using a spinner method or the like. By heating and curing this.

Flexible insulating substrate made of super heat-resistant polyimide (
37) is obtained. Vacuum deposited on one surface of it.

This g! Wiring portions (341), (342) connected to both ends of each of the rows of thermal resistors (33), a common electrode (351) and an external circuit connection portion (352) electrically connected to the wiring portion (341). ), and a drive circuit connection part (35,) to which a drive element to be described later is connected is formed between the wiring part (341) and the wiring part (341). Thereafter, Ta
2O.

A wear-resistant protective film (not shown) is attached to complete the heat generating resistor substrate (39). In addition, in Figure 1, (3
8) is a position where a drive element (40) consisting of an IC or the like, which will be described later, is fixed.

The heating resistor substrate (39) described above is bent so that the other surface (the surface opposite to the main surface on which the row of heating resistors (33) is arranged) faces inward, as shown in FIG. The heating resistor (33) row is made to have a substantially flat top surface. At this time, if the bent portions (41, 3) of the metal plate (30) are removed by etching or the like and bent to make it flexible, it is possible to prevent the wiring (34□) from opening due to cracks or the like. Further, in this case, distortion does not occur in the row of heat generating resistors (33), so that a uniform resistance value of the heat generating resistors (33) can be maintained.

Thereafter, as shown in FIG. 3, a metal member (41) having a substantially rectangular cross section and having good thermal conductivity made of aluminum, iron, copper, alloys mainly composed of these, etc. is prepared.

A row of heating resistors (33) is arranged on the substantially flat top surface (4L,) of this metal member (41) at the bent part (41,) and the wiring part (3).
The heating resistor substrate (39) is placed and bonded so that the corresponding parts of 4,) and (34□) are located. At this time, it is important to adhere a portion corresponding to the drive circuit portion to the substantially flat side surface (41□) of the metal member (41). It is also desirable to fill this bent portion (413) with an adhesive member from the viewpoint of improving strength. In addition, a groove (50) is formed in the part of the metal member (41) corresponding to the heating resistor board (39) as shown in the figure.
By forming , the metal member (41) and the heat generating resistor board (
39) will be prevented from being misaligned.

Next, the drive element (40) is fixed at the position (38), and the electrodes of the drive element (40) are connected to the wiring part (34□) and the external connection circuit connection part (35,) using bonding wires (
42), the thermal head of this embodiment is completed. Of course, the heating resistor (3
3) An insulating protective film is provided in the vicinity of the group, and an organic resin protective layer is provided on the drive element and the connection wire.
It is omitted in the drawings and description.

According to this embodiment, the heating resistor (33) row is a metal member (
Because it is located on the almost flat top surface (41□) of 41),
Unlike the thermal head disclosed in JP-A-57-131576, the heating resistor (33) is not bent, and the resistance value of each heating resistor (33) is no longer distorted, resulting in extremely stable heat generation. The resistance value of the resistor (33) is obtained. This allows each heating resistor (3
Since the print density obtained from 3) becomes constant, extremely stable printing can be performed.

Furthermore, since the heating resistor (33) is located on the substantially flat top surface (UZ), it is possible to prevent cracks from occurring in one row of heating resistors (33), and even breakage of the heating resistor (33) row. can be prevented.

Further, according to this embodiment, the heating resistor (33) row, the wiring portion (34□), (34□), the common electrode (35□), the external circuit connection portion (35□), and the drive circuit connection portion ( 35,)
However, a flat super heat-resistant organic resin substrate (37) was prepared in advance.
can be formed in high density on one surface of the film using thin film technology. Furthermore, there are few wirings such as bonding wires in the wiring portions (341) and (34□). Moreover, the super heat-resistant organic resin substrate (37) can be formed thin and uniformly, and the heat from the heating resistor (33) row can be quickly transferred to the metal member (41).
) can be released to the outside through the heat exchanger, making it possible to make the thermal characteristics uniform. Furthermore, since the thermal head is miniaturized, there is an effect that the recording device can also be miniaturized.

〔Effect of the invention〕

As described above, the present invention has the following effects.

(2) Since the heating resistor rows are arranged on a flat surface, that is, a substantially flat top surface of the heat dissipating base, the resistance values of the individual heating resistors do not differ. This stabilizes the density of the print from each heating resistor, making it possible to perform extremely stable printing.

(2) Since the heating resistor array and the drive circuit section are formed of a flat substrate, high density is possible.

■ Wiring such as bonding wires between the heating resistor array and the drive circuit section can be reduced.

(a) It is possible to provide a thermal head that can be made extremely compact as a recording device.

■ A heat-resistant organic resin film is applied to a metal plate using a spinner method, etc., so a thin and uniform insulating film can be obtained.

■ Since all the shoulder members are used as a heat dissipation board, the heat dissipation characteristics are good and the high-speed thermal response is good.

(2) Unlike conventional thermal heads, the thermal head of the present invention forms wiring, etc. on a flat substrate by photo-etching, so that general photo-etching equipment can be used as is.

■ Since an expensive ceramic substrate is not used, an inexpensive thermal head can be provided.

[Brief explanation of the drawing]

1 to 3 are diagrams showing one embodiment of the present invention,
Fig. 1 is a partially cutaway perspective view showing a state in which a heating resistor array, wiring section, and drive circuit section are formed on a super heat-resistant organic resin substrate laminated on a metal plate, and Fig. 2 is a partially cutaway perspective view of the heating resistor shown in Fig. 1. FIG. 3 is a simplified perspective view of the main part of the completed thermal head, with a part cut away. (30)...Metal plate (33)...Heating resistor (34□), (3'!2)...Wiring part (35□)...
・Common electrode (35□)...External circuit connection part (353)...Drive circuit connection part (37)...Super heat-resistant organic resin substrate (39)...Heating resistor substrate (40)...・Drive element (4I)...Metal member (42)...Bonding wire representative Patent attorney Norihiko Ken Yudo Ogo Norio Figure 1 Figure 2 Figure 8

Claims (7)

[Claims] (1) An insulating substrate made of a heat-resistant organic resin adhered to a metal plate, a row of heating resistors arranged on the heat-resistant organic resin layer on the insulating substrate, and electrically connected to the row of heating resistors. wiring section,
and a driving element electrically connected to the wiring portion, and a heat dissipating base on which the insulating substrate surface is placed, the heat dissipating base having a substantially flat top surface and a substantially flat side surface. A thermal head, characterized in that the heating resistor array is located on the top surface of the heat dissipating base, and the driving element is located on a side surface of the heat dissipating base. (2) The thermal head according to claim 1, wherein the material of the heat dissipating base is metal. (3) The thermal head according to claim 1, wherein the heat-resistant organic resin is made of ultra-heat-resistant polyimide. (4) The thermal head according to claim 2, wherein the metal plate is made of aluminum, iron, copper, or an alloy mainly composed of these. (5) The thermal head according to claim 1, wherein at least a protective layer is disposed on the heating resistor array. (6) Forming an insulating substrate from a heat-resistant organic resin layer obtained by applying and curing a varnish-like heat-resistant organic resin on one main surface of a metal plate; a step of laminating a heating resistor layer and a wiring layer on the heating resistor layer and a wiring layer; a step of forming a heating resistor part and a wiring part from the heating resistor layer and the wiring layer; the insulating substrate along the shape of the heat dissipating base so that the heat dissipating substrate is located; and the step of placing a driving element at a predetermined position on the insulating substrate. A method for manufacturing a thermal head. (7) The step of mounting and fixing the insulating substrate along the shape of the heat dissipating substrate so that the heat generating resistor portion is located on the substantially flat top surface of the heat dissipating base is carried out at the bent portion of the insulating substrate. The metal plate corresponding to the heat dissipating base is removed, and the bent portion is bent so that the heating resistor portion is located on the substantially flat top surface of the heat dissipating base, and the insulating substrate is placed and fixed on the heat dissipating base. 7. The method of manufacturing a thermal head according to claim 6, further comprising the step of: