JP2965339B2 - Manufacturing method of thermal head - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a thermal head in a thermal recording apparatus used as a print output unit of various information processing apparatuses such as a facsimile apparatus and a printer.

[Conventional technology]

The thermal recording device has low operating noise during printing, and
Since a developing and fixing process is not required unlike an electrophotographic recording apparatus, it has been widely used.

A thermal head, which is a recording head of this type of thermal recording apparatus, includes a heating element including a plurality of resistors arranged on an insulating substrate, and an electrode for supplying a current to the heating element.
By selectively causing the heating element to generate heat through the electrodes, characters or figures are recorded on a recording medium such as thermal paper or plain paper via an ink donor film.

There are two types of thermal heads, a thin-film thermal head and a thick-film thermal head, depending on the manufacturing method.

The thin-film thermal head is formed by forming the above-mentioned components such as the heating element and the electrodes on an insulating substrate by using a thin-film forming technique such as vapor deposition and sputtering.

On the other hand, a thick-film type thermal head is one in which a paste is applied on an insulating substrate by a printing technique, and the paste is baked to form components such as the heating element and the electrodes.

Japanese Patent Publication No. Sho 63-9728 discloses a conventional technique relating to a thick film type thermal head.

[Problems to be solved by the invention]

The thin-film type thermal head has the advantage that high-density and uniform printed dots can be obtained because it can form minute electrodes and heating elements, but has the disadvantage that the manufacturing equipment is large-scale and the cost is high. There is.

On the other hand, the thick-film type thermal head forms electrodes and heating elements by printing and baking paste, so the manufacturing equipment is simple and low cost, but the variation in resistance value of the heating elements is large. Therefore, there is a disadvantage that a resistance trimming process must be performed to make the print dots uniform.

Considering the wear-resistant layer (overglaze layer) of this type of thermal head, in the case of a thin film type, it is necessary to form a required wear-resistant layer of 2 μm or more using a vacuum device such as sputtering. No.

 Therefore, there is a problem that the throughput is small.

On the other hand, in the case of the thick film type, the abrasion-resistant layer has a softening point of 800.
Since glass powder (such as lead borosilicate) having a temperature of not more than ℃ is used as a raw material, its Vickers hardness is about 500 to 800, its hardness is low as a wear-resistant layer, and its surface smoothness is not good.

In order to increase the hardness, there is a method of improving the surface smoothness of the film quality by changing the firing temperature stepwise as disclosed in, for example, JP-A-63-9728.

Further, in order to improve abrasion resistance, it is common to add ceramic powder as a filler, but this reduces the surface smoothness.

Such a decrease in surface smoothness is caused by the occurrence of background streaks and the air gap between the abrasion-resistant layer and the recording medium when recording on sublimation type recording paper via thermal paper or an ink donor film. This causes dot shape irregularities and density unevenness, which is one of the causes of deteriorating the recording quality of a thick-film type thermal head.

An object of the present invention is to solve the above-mentioned problems of the prior art, without using a large-scale manufacturing apparatus used for forming a thin film,
An object of the present invention is to provide a high-quality thermal head having good abrasion resistance and surface smoothness.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a method for manufacturing a semiconductor device comprising: a glass heat storage layer (2 in FIG. 1); electrodes (common electrodes 3a and individual electrodes 3b in FIG. 1) on an insulating substrate (1 in FIG. 1); A heating resistor (resistance layer 4 in FIG. 1) and an overglaze layer are formed, and the overglaze layer is an overglaze lower layer (5 in FIG. 1) formed by printing / firing a glass paste containing a filler. And a thick film type thermal head comprising: an overglaze upper layer (6 in FIG. 1) formed by printing / firing an amorphous glass paste containing no filler; After forming the overglaze upper layer thereon, a lapping treatment for exposing a part of the overglaze lower layer is performed to thereby obtain good wear resistance and surface smoothness.

[Operation] A common electrode, an individual electrode, a resistance layer having heat generation resistance, and an overglaze layer constituting a thermal head are printed in paste form using respective constituent materials.
The layer is formed by a thick film technique formed by firing. Therefore, a large-scale apparatus used in the thin film formation technique is not required.

In addition, the overglaze lower layer is filled with irregularities generated on the surface of the overglaze lower layer by using a high-hardness material mixed with a filler such as a ceramic, and the overglaze lower layer is formed by an amorphous glass paste without filler having a good smoothness. Cover the glaze upper layer on the surface of the overglaze lower layer,
By subjecting the overglaze upper layer to a lapping treatment so that the lower portion of the overglaze is exposed mainly at a portion that slides with the recording medium, a thermal head that maintains abrasion resistance while maintaining surface smoothness can be obtained.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an explanatory view of the structure of a thermal head manufactured by one embodiment of the method of manufacturing a thermal head according to the present invention.

In the figure, 1 is an insulating substrate made of a ceramic material or the like, 2 is a glass heat storage layer, 3 is a common electrode, 4 is a resistance layer as a heating resistor, 5 is an overglaze lower layer, 6 is an overglaze upper layer, and 7a and 7b. Is a common electrode pad for connecting a power supply terminal for supplying an external current to the common electrode 3a and the individual electrode 3b, respectively, and 8 is a heating area (dot).

In this embodiment, the structure of a thermal head of a type in which a portion of a resistive layer 4 bridging between electrodes in which an individual electrode 3b is alternately arranged on a comb-shaped common electrode 3a is used as a heating region 8 will be described.

An overglaze lower layer 5 is formed by covering the upper surfaces of the resistance layer 4 and the common electrodes 3a and the individual electrodes 3b and mixing a filler such as a ceramic powder.

The overglaze upper layer 5 is polished and removed by lapping at the portion where the overglaze lower layer 5 contacts the recording medium (sliding portion) so as to be exposed from the overglaze upper layer 6.

Since the overglaze upper layer 6 does not contain a filler and is made of an amorphous glass material, the surface smoothness is good.

By coating the overglaze upper layer 6 on the surface of the overglaze lower layer 5, unevenness on the surface of the overglaze lower layer 5 can be filled, and the surface smoothness in the exposed portion can be improved.

Further, since the overglaze lower layer 5 exposed from the overglaze upper layer 6 has high hardness, it is possible to reduce abrasion due to sliding with the recording medium.

In other words, the overglaze layer in the portion corresponding to the heat generating region that slides in the strongest contact with the recording medium is made of a high-hardness material without an air gap, and is large in contact with the recording medium over a wide area. A portion of the overglaze layer is made of a material having good smoothness.

As a result, a decrease in the recording quality as in the related art is eliminated.

FIG. 2 is an explanatory view of one embodiment of a method of manufacturing a thermal head according to the present invention. Hereinafter, description will be made in accordance with the steps shown in FIGS.

First, an insulating substrate 1 made of an insulating material such as alumina is prepared. (A) A glass paste made of a glass-based material is applied to one surface of the insulating substrate 1 and fired, so that the glass heat storage layer 2 is applied. (B) Next, for example, a metal organic paste containing gold (metallo organic gold paste) is printed in a solid color, and the resultant is baked.
The AU conductor film 30 is formed. (C) A photoresist is applied on the AU conductor film 30 and dried,
This is exposed and developed through a photomask to remove unnecessary parts.
The AU conductor film is exposed.

The exposed AU conductor film is etched away by performing an etching process using, for example, an iodine-potassium iodide aqueous solution as an etching solution (photolithography etching process).

Thereafter, the common electrode 3a and the individual electrode 3b are obtained by removing the photoresist. .... (d) Ruthenium oxide thick film resistor paste (for example, GZX paste-trade name, manufactured by Tanaka Mansei Co., Ltd.) is printed in a strip shape across the formed common electrode 3a and individual electrode 3b, and this is printed. 130
After drying at a temperature of 800 ° C., the resistor 4 is formed by firing at a peak temperature of 800 ° C. ... (E) A glass paste (for example, Tanaka) in which ceramics powder such as alumina powder is mixed as a filler so as to cover the entirety of the resistor 4 and the common electrode 3a and the individual electrodes 3b except for the pad portions. Massey LS201 or ESL 4903
H, each of which is a trade name, is printed on a 400 mesh screen and fired at a peak temperature of 800 to 820 ° C. to form the overglaze lower layer 5. ...
(F) Further, an amorphous glass paste containing no filler and having a low softening point (for example, NP manufactured by Noritake Co., Ltd.)
7240, or 19449, manufactured by Sumitomo Metal Mining Co., Ltd., each of which is a trade name) is printed through a 400 mesh calender screen and fired at a peak temperature of 600 ° C. to form the overglaze upper layer 6. (G) The reason why the glass having a low softening point is used for the upper layer of the overglaze is to improve the surface smoothness of the thermal head and not to change the resistance value of the resistor of the resistance layer 4. .

FIG. 3 is an explanatory view of an example of measured values of the surface smoothness of the overglaze layer, wherein (a) shows a case where only an overglaze lower layer containing a filler is mixed, and (b) shows a case after forming an overglaze upper layer without a filler. Shows the surface roughness (Ra) of the sample.

As shown in the figure, the surface roughness of only the overglaze lower layer 5 is Ra = 0.635.

In contrast, when an overglaze upper layer made of an amorphous glass paste was formed, Ra = 0.026,
It is about 1/20 compared to the case of the overglaze lower layer only.

That is, by providing the overglaze upper layer 6, the surface smoothness of the overglaze layer is remarkably improved.

Under normal operating conditions of the thermal head, it can be used as it is, but for those requiring higher wear resistance, as shown in FIG. 2 (g), a wrapping sheet or the like is used. The overglaze upper layer 6 is wrapped so that a part of the overglaze lower layer 5 is exposed.

As a result, an excellent thermal head having good surface smoothness and improved abrasion resistance can be obtained.

In the embodiment described above, the common electrode 3a and the individual electrode 3b are alternately arranged in the main scanning direction of the thermal head, and the thermal head has a resistance layer formed in a strip shape across the common electrode 3a and the individual electrode 3b. However, the present invention is not limited to such a type of thermal head, but a thermal head of a type in which a common electrode and an individual electrode are arranged facing each other in the sub-scanning direction, and a resistance layer is formed independently for each dot. Applicable to various types of thermal heads and other existing thermal heads.

〔The invention's effect〕

As described above, according to the present invention, a thermal head with good recording quality can be obtained by forming the overglaze layer of a thermal head from a lower layer having high hardness and an upper layer having good surface smoothness. Can be.

Conventionally, there are two types of overglaze layers, but this is to form a glass layer without filler as an antioxidant film of the resistive layer in the lower layer, and abrasion-resistant glass layer with filler on the upper layer. Is formed as
The present invention is a concept completely opposite to such a conventional technique.

Further, since each constituent layer is formed by the thick film technology, there is an effect that the manufacturing equipment is simple, the productivity is good, and a thermal head of low cost and high quality can be manufactured.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram of a structure of a thermal head manufactured by one embodiment of a method of manufacturing a thermal head according to the present invention;
FIG. 2 is an explanatory view of one embodiment of a method for manufacturing a thermal head according to the present invention, and FIG. 3 is an explanatory view of an example of measured values of the surface smoothness of the overglaze layer. DESCRIPTION OF SYMBOLS 1 ... Insulating substrate, 2 ... Glass heat storage layer, 3 ... Common electrode, 4 ... Resistance layer, 5 ... Overglaze lower layer, 6 ...
... overglaze upper layer, 7a, 7b ... electrode pad, 8 ...
... heat generation area.

Claims (1)

(57) [Claims] A glass thermal storage layer, an electrode, a heating resistor, and an overglaze layer are formed on an insulating substrate, and the overglaze layer is formed by printing / firing a glass paste containing a filler. And an overglaze upper layer formed by printing / firing an amorphous glass paste containing no filler, wherein an overglaze upper layer is formed on the overglaze lower layer. A method for manufacturing a thermal head, comprising: performing a lapping process for exposing a part of an overglaze lower layer after forming a film.