JPH05201048A - Thick film type thermal head and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a thick film type thermal head and manufacture method thereof, which can reduce defects of the conductor without being influenced by the surface condition of the base, and at the same time, for which a specified conductor can be easily formed. CONSTITUTION:A glaze 11 is provided on a ceramic base 10 in the printing scanning direction, and an Au conductor 12 is formed in such a manner that the Au conductor alternately goes across the glaze 11, and a thermal resistor 14 is provided on the glaze 11, and in addition, these constituents are covered by a protective glass 15 for the title thick film type thermal head. For such a thick film type thermal head, the film thickness of the Au conductor 12a, which is on the surface of the base 10 is made thicker than the film thickness of the Au conductor 12b on the glaze 11. Therefore, the unevenness on the surface of the base 10 due to protuberances or pores is smoothed by thickening the Au conductor 12a on the base 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thick film type thermal head used in a printing apparatus such as a facsimile, a printer, a word processor, etc., and a method for manufacturing the same. The present invention relates to a thick film type thermal head characterized by being thicker than the film thickness of a conductor and a manufacturing method thereof.

[0002]

2. Description of the Related Art A thick film type thermal head used in a printing apparatus generally has a structure shown in FIG. 3 (partial external perspective view) and FIG. 4 (main part sectional view). The thick film type thermal head shown here is an insulating substrate 30 made of ceramic or the like.
A glaze 31 provided on the insulating substrate 30 in the print scanning direction, another glaze 31a provided at a constant interval from the glaze 31, and the substrate 30 and the glaze 31 so as to cross the glaze 31 alternately. The one conductor 32 and the other conductor 33 which are extended to the glaze 31
The heating resistor 34 provided above and the protective glass 35 (see FIG. 4) covering these components are provided. The conductors 32 and 33 are generally made of Au, and alternately contact the lower portion of the heating resistor 34 at equal intervals, and extend from the substrate 30 to the middle of the glaze 31.

In such a thermal head, when one conductor 32 and the other conductor 33 adjacent thereto are energized, a heating resistor for one dot located between the conductors 32, 33 is generated. Heat is generated and printing is performed.

[0004]

In the above-mentioned thermal head, the heating resistor 34 is raised from the substrate 30 by the glaze 31. This is to improve the contact condition of the heating resistor 34 with the platen roller. . In this case, the conductor 32 is the portion 32 on the substrate 30.
a and a portion 32b existing on the glaze 31 (the same applies to the conductor 33).

By the way, the Au conductors 32 and 33 are thinly formed on the surfaces of the substrate 30 and the glaze 31 by printing and firing, and then are formed by photolithography into a pattern as shown in FIG. The surface of 30 often has protrusions and pores (recesses). In such a case, during etching in photolithography, due to the influence of projections and pores, there arises a disadvantage that Au remains in a portion other than the conductor pattern or a part of the conductor pattern is lost. In particular, if the intervals between the conductor patterns are made narrower and the density is higher, the conductor patterns are more likely to be short-circuited due to the protrusions and pores.

In order to solve the above problems, it has been attempted to increase the film thickness of the conductor as a whole. However, if the Au film is simply thickened, the portion becomes too thick (particularly in FIG. 3).
Au foams at the portion surrounded by the dotted line), and it becomes impossible to form a predetermined conductor pattern. Therefore,
An object of the present invention is to provide a thick film type thermal head capable of reducing defects of a conductor and easily forming a predetermined conductor without being affected by the surface condition of a substrate, and a manufacturing method thereof. To provide.

[0007]

In order to achieve the above object, the thick film type thermal head of the present invention is a conventional thick film type thermal head in which the thickness of the conductor on the substrate is on the glaze. It is characterized by being thicker than the film thickness of the conductor.
This thermal head manufacturing method is characterized in that, in the conventional manufacturing method, there is a step of making the film thickness of the conductor on the substrate larger than the film thickness of the conductor on the glaze.

With this structure, the projections and irregularities due to the pores on the surface of the substrate are smoothed. Therefore, in photolithography performed after the formation of the conductor film, the conductor pattern is also etched at the time of etching due to resist coating failure due to the projections on the substrate surface. Not only will it not be done,
The resist is applied to the pores (recesses) more than necessary, the resist does not peel off due to development, and Au does not remain in the pores even after etching.

As a specific step of thickening the conductor on the substrate, screen-printing glass frit gold on the conductor on the substrate or repeatedly printing and firing resinate gold is shown. .. However, in the former process, the conductor can be made considerably thicker by one printing, but in the latter process, printing and firing must be repeated many times to obtain a predetermined conductor film thickness.

It is sufficient that the conductor film thickness on the substrate is thicker than the conductor film thickness on the glaze, but actually the conductor film is thickened as described in the graph of FIG. 2 in the following embodiments. Considering that the number of defects in the conductor pattern decreases, it is preferable that the thickness is at least about 1.0 μm or more.

[0011]

EXAMPLES A thick film type thermal head and a method of manufacturing the same according to the present invention will be described below based on examples. However, the external structure of the thermal head is the same as that of the conventional one shown in FIG. That is, in FIG. 1, a glaze 11 is linearly formed in the print scanning direction on an insulating substrate 10 made of ceramic or the like, and another glaze 11a is formed at a position spaced from the glaze 11 at a constant interval. There is. Board 1
On the 0, one conductor 12 is provided so as to cross the glaze 11, and on the glaze 11, a heating resistor 14 is provided along the glaze. Furthermore, these components are covered with a protective glass 15.

The conductor 12, which is a feature of the present invention, is made of Au, and the film thickness of the portion 12a on the substrate 10 is the glaze 1.
It is thicker than the film thickness of the portion 12b located above 1. Of course, one conductor 12 and the other conductor (not shown in FIG. 1)
Are staggered at equal intervals 11 as shown in FIG.
Is patterned to cross. Next, a method of manufacturing the thick film type thermal head will be briefly described. First, a glaze 11 is provided at a predetermined position on the ceramic substrate 10 along the print scanning direction, and then Au is printed and fired on the entire surfaces of the substrate 10 and the glaze 11 in the conventional manner to form an Au film. At this stage, the Au conductor 12b on the glaze 11
Is formed to have a predetermined film thickness.

Next, glass frit gold is printed on the Au film existing on the surface of the substrate 10 by screen printing so that the thickness of the Au film becomes thicker than the thickness of the Au film existing on the surface of the glaze 11. And cure. As a result, projections and depressions due to pores on the surface of the substrate 10 are smoothed. Then, in order to perform photolithography, a photoresist is applied onto the Au film on the substrate 10 having a predetermined thickness, the photoresist is cured to have an appropriate film quality, and a predetermined pattern (see the conductors 32 and 33 in FIG. 3) is baked. The photomask is brought into close contact with the surface of the photoresist, or is slightly separated for alignment. Then, it is exposed to UV light and developed with a developing solution to transfer the pattern of the photomask onto the photoresist.

Using the remaining photoresist as a protective mask, the Au film not covered with the protective mask is etched in a pattern, and then the remaining photoresist on the substrate 10 is removed. As shown in FIG. A conductor pattern is obtained. Then, the heating resistor 14 is formed on the glaze 11.
Is formed, and the whole is covered with the protective glass 15, whereby the thermal head is manufactured.

Although the above-mentioned manufacturing method relates to screen printing using glass frit gold, printing and firing using resinate gold is almost the same, and printing and firing are repeated to repeat Au on the substrate surface. After thickening the membrane,
Photolithography may be performed as described above. FIG. 2 is a graph showing that a conductor with few defects can be obtained by using the manufacturing method of the present invention. This graph shows a conductor width of 20 μm
Shows the relationship between the film thickness (μm) of the Au conductor in 1700 lines and the number of defects (pieces) generated in the conductor pattern. This shows that the number of pattern defects decreases as the conductor film thickness on the substrate increases. Therefore, also from this graph, as described above, the thickness of the Au film existing on the substrate is preferably at least about 1.0 μm or more.

[0016]

As described above, in the thick film type thermal head of the present invention, since the film thickness of the conductor on the substrate is thicker than the film thickness of the conductor on the glaze, the surface condition of the substrate ( It is not affected by projections and irregularities due to pores, has a conductor with few defects, and has high reliability. Further, since the manufacturing method of the present invention has a step of making the film thickness of the conductor on the substrate larger than the film thickness of the conductor on the glaze, in photolithography after the formation of the conductor (Au film), It is possible to easily form a conductor having no defect without causing inconvenience such as Au remaining in a pattern other than the predetermined pattern and Au loss in the predetermined pattern.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts of a thick film thermal head according to an embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the film thickness of an Au conductor and the number of defects in its conductor pattern.

FIG. 3 is a partial external perspective view of the thermal head shown in FIG.

FIG. 4 is a cross-sectional view of essential parts of a thick film thermal head according to a conventional example.

[Explanation of symbols]

 10 Ceramic Substrate 11 Glaze 12 Au Conductor 12a Au Conductor 12b on Substrate Surface Au Conductor on Glaze 14 Heating Resistor 15 Protective Glass

Claims (4)

[Claims] 1. A substrate, a glaze formed in the print scanning direction on the substrate, a conductor extending from the substrate onto the glaze so as to cross the glaze at regular intervals, and along the glaze along the glaze. A thick-film thermal head comprising a heating resistor provided on the substrate, wherein the conductor on the substrate is thicker than the conductor on the glaze. 2. A glaze is formed on a substrate in a print scanning direction, a conductor is extended from the substrate onto the glaze so as to cross the glaze at regular intervals, and a heating resistor is formed on the glaze along the glaze. In the method for manufacturing a thick film thermal head, the thick film thermal head is characterized by including the step of making the film thickness of the conductor on the substrate larger than the film thickness of the conductor on the glaze. Head manufacturing method. 3. The method for manufacturing a thick film type thermal head according to claim 2, wherein said step comprises screen-printing glass frit gold on a conductor existing on the substrate. 4. The method for manufacturing a thick film type thermal head according to claim 2, wherein the step comprises repeatedly printing and firing resinate gold on a conductor existing on a substrate.