JPH04122652A - Manufacture of end face thermal head - Google Patents

Abstract

PURPOSE:To make it possible to print even on a record medium which can not be folded easily by covering protruded strips formed on the surface of a substrate with a glaze layer, forming a heating element arranged along the direction to the protruded strips, an electrode connected thereto, a protective film and bonding pad on the glaze layer, and cutting off the substrate at an interstice of the protruded strips so as to stick to an end face of a support plate. CONSTITUTION:A plurality of protruded strips are formed on the surface of a substrate 2. The protruded strips are covered with a glaze layer 4. A heat element 6 arranged along the direction of the protruded strips, an electrode 12 connected thereto, a protective film 14 and a bonding pad 16 are formed on the glaze layer. The substrate is cut off at an interstice of the protruded strips, and then, it is stuck to an end face of a support plate 18. At this time, the heating element 6 is to be formed in a position deviated from the top position of the protruded strip in order to make it easy to make electrodes 6, 8, 10 patterned. Also, in order to make it easy to connect to a semiconductor integrated circuit device 22 for driving the heating element, the back face of the substrate is polished in an oblique direction such that the heating element comes to the top position of the protruded strip after the substrate is cut off.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a thermal head used in printers, facsimile machines, and the like.

(Prior Art) A general type of thermal head is a so-called planar thermal head in which a heating element is formed on the main surface of a heating substrate. The planar thermal head is easy to manufacture, whether it is a thin film thermal head or an original model thermal head.

Due to the diversification of thermal recording technology and recording media, the number of thermal transfer recordings has increased in recent years, and many of the recording media are hard and thick, such as plastic cards and price tags. In a flat thermal head, the mounting part of the driving semiconductor device is present in the paper passing range, so if you try to print on a recording medium such as a plastic card or cardboard with a flat thermal head, the hardness and stiffness of the recording medium may be affected. There is a problem that paper cannot be passed due to the strength of the paper, and printing is not possible.

Attempts to solve this problem with planar thermal heads include lowering the mounting part of the driving semiconductor device and lowering the protective cover as much as possible, but even then, plastic cards are too stiff and printing is difficult. I can't.

As a thermal head convenient for printing on recording media that are difficult to fold, such as plastic cards, a so-called edge-type thermal head in which a heating element is formed on the end surface has been developed (Japanese Utility Model Publication No. 59-59342, (See Japanese Patent Application Laid-Open No. 1985-19557, etc.).

(Problems to be Solved by the Invention) In the conventional edge-type thermal head, the heating element is formed on the end surface of the substrate, and the electrode is formed on the main surface of the substrate. Therefore, the manufacturing process of forming a patterned heating element on the end face and connecting it to the electrode on the main surface is difficult, and even if it can be manufactured, it will be expensive.

In addition, since there are only two end faces on a single board where heating elements can be formed, it is not possible to form three or more thermal heads from a single board, making it unsuitable for mass production. do not have.

The present invention provides an edge-type thermal head that can print on recording media that are difficult to fold, such as plastic cards, and improves print quality by improving contact with the recording media, in a mass-producible manner. The purpose is to provide an easy manufacturing method.

(Means for Solving the Problems) In the present invention, a plurality of protrusions are formed on the surface of a substrate, the protrusions are covered with a glaze layer, and the protrusions are arranged on the glaze layer along the direction of the protrusions. heating element, electrodes connected to it,
The method includes the steps of forming a protective film and bonding pads, cutting the substrate between the protrusions, and then attaching them to the end surface of the support plate.

In order to facilitate patterning of electrodes, etc., the heating element is formed at a position shifted from the apex position of the convex strip.

In addition, in order to facilitate connection to a semiconductor integrated circuit device, etc. that drives the heating element after pasting the substrate on which the heating element is formed on the support plate, it is necessary to cut the substrate and attach the heating element to a protruding strip. Polish the back side of the substrate diagonally so that it comes to the apex position of the part.

(Example) One embodiment will be described with reference to FIGS. 1 to 4.

As shown in FIG. 1, a plurality of protrusions are formed on the surface of a substrate 2 made of ceramic or the like. When the substrate 2 is made of ceramic, the protrusions may be formed by shaping using a mold made of plaster or the like and firing. The width of the protruding portion a is 1 to 2
It is mm.

The protruding stripes are covered with a glassy glaze layer 4.

Ta2N or TaS is applied to the entire surface of the substrate on which the convex stripes are formed.
A resistor layer such as i02 is formed, and an electrode layer such as an aluminum electrode layer or a laminated film of NiCr and Au is formed thereon. The electrode layer and the resistor layer are patterned by photolithography and etching to form a heating element, a selection electrode, and a common electrode.

FIG. 2 shows a pattern of the heating elements 6, the common electrode 8, the selection electrode 10, etc. The heating elements 6 are formed so as to be arranged in the longitudinal direction of the ridges a. FIG. 3 shows a state in which a protective film has also been formed. The heating element 6 is formed at a position offset from the apex (position on line b) of the cross section of the convex strip. The heating elements 6 are one pair of adjacent ones 6a and 6b.
They constitute heating elements for bits, and are connected by a folded electrode 12. One heating element 6a is connected to the selection electrode 10, the other heating element 6b is connected to the common electrode 8, and the heating element 6a is connected to the selection electrode 10. and the common electrode 8 are drawn out in the same direction with respect to the heating element array.

After that, a protective film 14 is formed on the entire surface. For example, Si3N is used as the protective film 14. In particular, when durability is required, SiC or 5iAQ can be used as an additional wear-resistant layer.
Form an ON film, etc.

The protective film 14 is patterned by photolithography and etching, and the protective film at the bonding pad 16 portion is removed. The bonding band 16 is also formed at a position shifted from the apex position of the convex strip.

Next, the substrate 2 is divided into protrusions one by one at positions between the protrusions (positions indicated by C in FIG. 3). The dividing method may be by cutting with a grade or laser, or by splitting.

Although the back surface of the divided substrate may be attached to the end surface of the support plate, in this embodiment, the substrate 2 is polished diagonally at the position indicated by the symbol d.

On the other hand, as shown in FIG. 4, a lint wiring board 20 is pasted on the support plate 8, and the unpolished back side of the board 2 is pasted on the end surface of the lint wiring board 20, which is used as a support plate for the board 2. Put on.

After that, the semiconductor integrated circuit device (hereinafter referred to as EC) 22 of the heating element drive 1 is die-bonded to the printed wiring board 20, and the IC 22 and the bonding/nod 16 are bonded by wire bonding, and the IC 22 and the printed wiring board 2o are bonded. Wiring is also connected using wire bonding method,
Further, the bonding pad of one common pole and the wiring of the printed wiring board 2 are also connected by the wire bonding method.

The bonding portion including the IC 22 and wires is sealed with a sealing resin 24 such as silicone or epoxy resin.

By polishing the substrate 2 diagonally at position d shown in FIG. 3, when this base cedar is attached to the end face of the support plate, the heating element 6 is positioned at the apex position of the convex strip of the substrate. This makes it possible to improve printing characteristics, and also allows the bonding pad 16 to be brought closer to the printed wiring board 20, facilitating bonding work with the IC 22.

In FIG. 4, the support plate 18 and the printed wiring board 20 are pasted together, and the divided board 2 is pasted on the end face, but since the width 3 of the board 2 is narrow, about 1 to 2 mm, the width 3 shown in FIG. In this way, only the printed wiring board 26 may be used as the support plate, and the board 2 may be attached to the end surface of the printed wiring board 26.

(Effect of the invention) In the present invention, a plurality of protrusions are formed on the surface of the substrate, but in the process of forming heating elements and electrodes, a film is formed on the surface of the substrate,
Because the pattern is applied, it can be done using the same equipment and techniques used to form planar thermal heads, facilitating patterning and facilitating the manufacturing process.

By dividing one substrate into a plurality of protruding stripes, a large number of heat generating substrates can be formed at the same time, resulting in excellent mass productivity.

By shifting the heating element from the apex position of the protruding strip, the electrode pattern can be formed on a portion close to the flat surface of the protruding strip, making patterning even easier.Also, after dividing the substrate, the back surface can be cut diagonally. By doing so, the heating element can be located near the apex of the convex stripe and the bonding pad can be brought closer to the driving IC, so that printing characteristics are improved, the bonding process is facilitated, and the yield is improved.

In this way, according to the method of the present invention, an end face type thermal head can be manufactured easily and with good mass productivity.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing a state in which protrusions are formed on a substrate and a glaze layer is formed in one embodiment, and Fig. 2 is a heating element, an electrode, and a protective film on the protrusions (the protective film is not shown). 3 is a sectional view taken along line X-X in FIG. 2, FIG. 4 is a side sectional view showing a completed thermal head according to one embodiment, and FIG. FIG. 3 is a side sectional view showing a thermal head formed according to the embodiment. 2...Substrate, 4...Glaze layer, 6...Heating element, 8...Common electrode, 1o...Selection electrode,
14... Protective film, 16... Bonding pad, 18... Support plate, 20.26... Printed wiring board, 22... Drive IC9

Claims (3)

[Claims] (1) forming a plurality of protrusions on the surface of the substrate, covering the protrusions with a glaze layer, heating elements arranged along the direction of the protrusions on the glaze layer, and electrodes connected thereto; A method for manufacturing an edge-type thermal head, which includes a step of forming a protective film and bonding pads, cutting a substrate between protrusions, and then pasting the substrate to an end surface of a support plate. (2) The method for manufacturing an end face type thermal head according to claim 1, wherein the heating element is formed at a position shifted from the apex position of the convex strip. (3) After cutting the substrate, the back side of the substrate is polished in an oblique direction so that the heating element is located at the apex position of the convex strip.
A method for manufacturing an end face type thermal head described in .