JPS62233266A - Manufacture of thermal head - Google Patents

Abstract

PURPOSE:To prevent a resist from cracking and obtain a thermal head having high reliability by providing a partial glaze layer in the vicinity of the peripheral part of a substrate. CONSTITUTION:A substrate 101 is provided with shallow grooves 102 for splitting. Next, a partial glaze layer 103 is provided by screen printing. In this case, a partial glaze layer 103' is provided also at a peripheral part. A tantalum nitride layer is then deposited by sputtering. A heat generating resistor layer 104 is patterned by the application of a resist, exposure, etching and releasing of a resist pattern. After depositing a nichrome layer of 500Angstrom thick and a gold layer by sputtering, an electrode conductor layer 105 is similarly patterned. Then, a silicon oxide layer and a tantalum pentoxide layer are provided as a protective layer 106 by sputtering. A thermal head thus produced has an extremely high reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a thermal head, and in particular, to a method for manufacturing a thermal head.
The present invention relates to a method for forming multiple thermal heads from a single substrate.

(Prior art and its problems) Conventionally, a thin film type thermal head S is shown in Fig. 1.
As shown, a heat generating resistor layer 3 is formed on a ceramic substrate 1 having a glaze layer 2 formed on its surface, and a pair of S conductor layers 4 as a pair of M resistors are further formed on top of the ceramic substrate 1. The surface is covered with ralI5. By applying a voltage to the electrodes, a current of m flows through the portion of the heating resistor layer (heating region > 3A) existing between the electrodes and generates heat, and the heat is transmitted through the protective film 5 as shown in FIG. Gotoku, flat platen F
The color is transmitted to the recording paper P held between the two, and color development occurs.

However, in such a thermal head, the heat generating area 3A has a recessed structure corresponding to the thickness of the conductive layer 4.
The recording paper may not be able to make good contact with the heat generating area 3A, resulting in a problem of poor printing characteristics.

Therefore, as shown in FIG. 4, a serial type thermal head has been proposed in which a partial glaze layer 11 is disposed below the heat generating area 30A and the heat generating area is made convex. (Unexamined Japanese Patent Publication No. 56-159176) With this structure, the recording paper comes into good contact with the heat generating area 30A, so that high quality printing is possible.

By the way, such thermal heads are usually fabricated in several tens on one substrate at the same time, and then divided later.

For example, first, screen printing is performed on a ceramic substrate 10 on which a scribe line C consisting of a shallow groove is formed.
After forming the partial glaze layer 11 as shown in FIG. 5, forming a thin film resistor layer, patterning the heating paper layer by photolithography, forming a thin film conductor layer, and patterning and protecting the electrodes by photolithography. After forming a film, a large number of thermal heads are fabricated. Thereafter, it is divided along the scribe line C to form individual serial type thermal heads.

As described above, the process of forming a thin film thermal head requires at least two photolithography processes. In this photolithography process, the photomask must be brought into close contact with the substrate in order to maintain pattern accuracy when exposing the resist after applying the resist to the substrate on which the partial glaze layer has been formed.

However, when the resist is brought into close contact with the resist, cracks may occur in the convex portion where the partial glaze layer 11 is present, particularly in the outer portion 11', which may cause the heating resistor layer to split or reduce the pattern size. This caused a decrease in yield.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to prevent the occurrence of resist cracking in a photolithography process and to increase the manufacturing yield of thermal heads.

[Means for solving problems]

Therefore, in the present invention, a partial glaze layer is also formed in advance on the outer periphery of the substrate, which is the area that will eventually be removed.

[For production]

By forming a partial glaze layer on the outer periphery of the substrate, most of the cracks in the resist when it comes into contact with the photomask during the exposure process will occur on the partial glaze layer on the outer periphery, which is the cutout area, making it difficult to use. There will be almost no cracking of the resist at the desired locations.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIGS. 1A to 1Q are diagrams showing the manufacturing process of a serial type thermal head according to an embodiment of the present invention.

First, as shown in FIG. 1(a), shallow dividing grooves (scribe lines) 102 are formed on an alumina substrate 101 with a thickness of 0.64 mm and a size of 52 x 52 (aha).

Next, as shown in FIGS. 1(b) and 1(C), a partial glaze layer 103 is formed by screen printing. At this time, a partial glaze layer 103' is also formed on the outer periphery. (FIG. 1(b) corresponds to an enlarged view of the A-A cross section in FIG. 1(C).) Subsequently, a tantalum nitride (Ta2N) layer with a thickness of 500 nm is deposited by sputtering. Then, through resist coating, exposure, etching, and peeling off of the resist pattern by photolithography, the heating resistor layer 104 is formed.
pattern. (FIG. 1(d)) Furthermore, a nichrome (NiCr) layer with a thickness of 500 mm and a layer of 1.5. Similarly, an electrode conductor layer 10 is formed by photolithography using a bond on which a gold<Au) layer of m is deposited.
Butter 5.

Then, a silicon oxide (SiO□) film with a film thickness of 2p and a tantalum pentoxide<TaTa203) 1 with a film thickness of 8s are formed as a protective film 106 by sputtering (see FIG.
f)).

After 16 thermal heads are formed on the alumina substrate in this way, it is cut into pieces along the scribe line 102. (FIG. 1(g)) The thermal head thus formed follows the pattern design and is extremely reliable, and the manufacturing yield has also been significantly improved compared to the conventional one.

In the example, eight partial glaze layers 103' were added to the outer periphery of the substrate, but the number, position, shape, etc. of the partial glaze layers 103' are not limited to the example. It may be added as appropriate.

Further, it goes without saying that the material of each layer is not limited to the examples and can be changed as appropriate.

〔effect〕

As explained above, according to the method of the present invention, since the partial glaze layer is also formed near the outer periphery of the substrate, resist cracks occur in the functional area, that is, the element forming area, and pattern accuracy deteriorates. There is no decrease in yield due to the decrease, and it becomes possible to provide a highly reliable thermal head.

[Brief explanation of drawings]

Figures 1 (a) to (9) are manufacturing process diagrams of a thermal head according to an embodiment of the present invention, Figure 2 is a diagram showing a normal IIIW type thermal head, and Figure 3 is a diagram showing a manufacturing process using the same thermal head. 4 is a diagram showing an improved example of the same thin film type thermal head, and FIG. 5 is a diagram showing a part of the manufacturing process (after forming a glaze layer) of the thermal head shown in FIG. 4. It is. 101... Alumina substrate, 102... Scribe substrate, 103, 103'... Partial glaze layer, 104...
...Heating resistor layer, 105... Electrode conductor layer, 106.
...Protective layer. Figure 1 (e) Figure 1 (f) Figure 1 (9) Figure 1 (C)

Claims (1)

[Claims] In a method for manufacturing a thermal head in which a large number of thermal heads are formed on one substrate and then divided into a plurality of pieces, a glaze layer is partially formed in a pattern forming area prior to forming a heating resistor layer. In this method, a glaze layer is additionally formed on the outer periphery of the substrate, which is the ablation area.