JPH0632930B2 - Method of manufacturing thermal head - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a thermal head for a thermal printer, which is widely used as a print output device in various office automation equipment, and in particular, a method for manufacturing a thick film type thermal head. Regarding

[Background of the Invention]

The thermal head formed by the thick film technology is easy and inexpensive to manufacture, but the heating resistor formed by printing and firing the resistance paste has a contour along its outline due to the printing accuracy limit of screen printing. And fine undulations (unevenness)
It is undeniable that the occurrence of

FIG. 3 is an enlarged plan view of an essential part showing such a conventional thick film type thermal head. In the figure, reference numeral 1 denotes a substrate made of ceramic or the like, and a glass layer functioning as a heat storage layer is formed on at least a region where a heating resistor is to be formed on the surface of the substrate. 2 ... 3 ... are common electrodes and individual lead electrodes that are alternately formed at equal intervals, and each of the common electrodes 2 ... Is connected to a wide connection pattern electrode 2A. Each of the electrodes 2, 2A and 3 is formed into a desired shape by, for example, printing and firing a thick film Au paste, and then etching by a photolithographic technique, and the thickness thereof is set to several μm. 4 is
A heating resistor formed so as to cross the common electrodes 2, ... And the individual lead electrodes 3 ,.
It is formed by printing ₂ series resistance paste,
Its thickness is about 5 to 30 μm.

The heating resistor 4 has the common electrodes 2 and 2 adjacent to each other.
Each of the common electrodes 2 is divided into areas to be the heating areas S corresponding to one dot (in FIG. 3, only one heating area S corresponding to one dot is hatched).
By selectively energizing between the individual lead electrodes 3 and the individual lead electrodes 3, a desired heat generating region generates heat, and publicly known thermal printing is performed.

However, in the above configuration, since the heating resistor 4 whose outer shape is determined by screen printing is used as it is, fine waviness occurs on both sides of the long side of the strip-shaped heating resistor 4 as shown in FIG. For this reason, the above-described heat generation regions S cannot maintain the desired outer shape. Therefore, the thermally printed dots (printed output) are not uniform and are likely to be disturbed at the edge of each dot, which gives a certain limit to the improvement of print quality. The cause of the above-mentioned undulation is bleeding of the resistance paste from the pattern edge of the mesh for screen printing, the viscosity of the resistance paste,
Alternatively, this is due to the existence of the thickness of the electrodes 2 and 3 below the heating resistor 4, and this undulation is difficult to avoid in manufacturing.

Therefore, it is conceivable to remove the undulating portion of the heating resistor 4 by laser trimming and shape the long sides of the heating resistor 4 into a straight line, but laser trimming can be used to make the heating low antibody of a considerable thickness have a considerable length. It is difficult to apply it to mass production and leads to a large increase in cost, and the heating resistor 4 cannot be chemically etched at present.

[Object of the Invention]

The present invention has been made in view of the above circumstances, and an object thereof is to eliminate the above-mentioned conventional drawbacks, and the outer shape of the heating resistor is substantially linear, which greatly contributes to improvement of print quality.
Another object of the present invention is to provide a method of manufacturing a thermal head that is easy to manufacture.

[Outline of Invention]

The above object of the present invention is to set a shape of a strip-shaped heating resistor by a step of depositing a photosensitive resin thin film on a substrate on which a glass layer is deposited, and by exposing and etching the photosensitive resin thin film. The step of forming a narrow groove window corresponding to the above, the step of printing the resistor paste on both sides of the narrow groove window and the long sides of the narrow groove window and drying, and burning the photosensitive resin thin film. At the same time, the steps of firing the resistance paste and the steps of removing the heating resistor portion outside the narrow groove window in the fired heating resistor are substantially achieved by a method of manufacturing a thermal head.

According to a preferred embodiment of the present invention, the film thickness of the photosensitive resin thin film is 0.5 μm to 2 μm, and the film pressure of the heating resistor is 5 to 20 μm.

Further, according to a preferred embodiment of the present invention, the width of the removed heating resistor portion is 0.05 mm or more.

Further, according to a preferred embodiment of the present invention, the heat generating resistor portion to be removed is removed so as to be adhered to an adhesive tape and peeled off.

Further, according to a preferred embodiment of the present invention, the glass layer on the substrate is a crystallized glass layer at least at a portion in contact with the heating resistor.

Example of Invention

The present invention will be described below with reference to the embodiments shown in FIGS. 1 and 2. 1 (a), (b), and (c) are enlarged cross-sectional views of an essential part for explaining a manufacturing process, and FIG.
It is a plan view of relevant parts corresponding to the drawings, and in FIG. 1, the dimensional relationship of each layer does not correspond to the actual dimensional relationship for convenience of illustration. Further, in each of the drawings, the same reference numerals are given to those corresponding to the conventional example.

Reference numeral 1 denotes a substrate made of ceramic or the like, and a glass layer 5 is formed on a portion of the surface thereof corresponding to at least a region where the heating resistor 4 is to be formed, and the surface of the glass layer 5 is polished. The glass layer 5 is formed on the entire surface of the substrate 1 in each example, and the amorphous glass layer 5 is formed.
It has a two-layer structure of a and a crystallized glass layer 5b. That is, first, on the substrate 1, SiO ₂ , Al ₂ O ₃ , CaO
Printing a glass paste containing ₃ or the like as a main component,
By baking at 1000 ° C., the amorphous glass layer 5
a is formed. The amorphous glass 5a has a smaller thermal conductivity than the crystallized glass layer 5b, functions as a main component of the heat storage layer, and is set to have a thickness of about 20 to 50 μm.
On the amorphous glass layer 5a, a glass paste such as Ba, TiO ₂ or the like, to which a material serving as a nucleus for crystallization at the time of firing is added [eg, an Electro-Science Laboratorie]
s, Hnc made by Inc, or Tanaka Matsusei Co., Ltd.
Manufactured by LS301 etc.] and then baked at around 950 ° C., and its composition is crystallized in this baking and cooling process. This crystallized glass layer 5b is the same as 850 of the heating resistor 4.
To ensure high temperature firing at a temperature of ℃ or above with high reliability, there is no risk that the amorphous glass layer 5a may diffuse into the heating resistor 4 during the firing process of the heating resistor 4. In addition, when removing an unnecessary portion of the heating resistor 4 which will be described later, there is no possibility that the unnecessary portion will sag down and firmly adhere to the crystallized glass layer 5b. Since the crystallized glass layer 5b does not function as a main body of the heat storage layer, it is set to have a thickness of 3 to 25 μm.

Thus, when the glass layer 5 has a two-layer structure of the amorphous glass layer 5a and the crystallized glass layer 5b, the thickness of the entire glass layer 5 is reduced, and the number of screen printing / firing steps can be reduced. High-temperature firing of the heating resistor 4 can be reliably assured, and details of this are omitted here, but if necessary, the applicant's application for registration of a utility model dated June 18, 1985, See the name "Thermal Head".

On the glass layer 5 formed as described above, a thick film Au paste is screen-printed on a necessary area, baked, and etched by a photolithographic technique to etch the electrodes 2, ... 3 ... is formed. The film thickness of each of the electrodes 2, 2A, 3 is set to 1 to 5 μm, and in the embodiment, the film thickness is 3 μm, and the width of the common electrode 2 ... Two, two
The pitch between them is set to about 0.2 mm.

A photosensitive resin thin film 6 is deposited by spinner coating on the entire surface of the glass layer 5 on which the electrodes 2, 2A and 3 are formed, or on the area where the heating resistor 4 is to be formed and its periphery by a spinner coating. After being dried. Further, the film thickness of the photosensitive resin thin film 6 is preferably, for the reason described below,
It is set to 0.5 to 2 μm. This photosensitive resin can be selected as appropriate, for example, in the embodiment,
OMR83 manufactured by Tokyo Ohka Kogyo Co., Ltd. is used.

After that, the photosensitive resin thin film 6 is selectively exposed and etched by a known photo process to form a narrow groove window 6a corresponding to the set shape of the narrow heating resistor 4 to be formed.
Is provided.

Then, on the glass layer 5 exposed in the narrow groove window 6a and on both long sides of the narrow groove window 6a connected to the glass layer 5, for example, Ru.
An O ₂ -based resistance paste is applied to a predetermined thickness by screen printing, and then dried at about 150 ° C. This resistance paste has an average width W _{2 of a} portion protruding from the set width W ₁ of the heating resistor 4 (in other words, the width of the narrow groove window 6a).
However, the thickness is preferably 0.05 mm or more. The reason for doing this is that the above-mentioned “waviness” that occurs in screen printing is almost completely within this range,
Further, the heating resistor portion 4 protruding from the narrow groove window 6a described later.
This is because, when removing a (hereinafter referred to as the removed portion 4a), the removed portions 4a are connected to each other to facilitate removal by the adhesive tape. The resistance paste is set so that the thickness of the heating resistor 4 after firing is preferably 5 to 20 μm. That is, if the film thickness of the heating resistor 4 is 5 μm or more, it has a resistance value sufficient to function as a heating element, and if the film pressure of the heating resistor 4 is 20 μm or less, a heating resistor described later will be described. This is because the step of removing the removed portion 4a of No. 4 can be performed with high reliability. (This is because the bonding force between the heat generating resistor 4 remaining on the glass layer 5 and the removed portion 4a does not become so large.) In FIG. 1 (a), the resistance paste is printed and dried by the above-described process. Shows the closed state. From this state, the heating resistor 4 is then fired at 850 to 900 ° C., whereby the photosensitive resin thin film 6 is burned and vaporized (blown) to reach the state shown in FIG. 1 (b). . In this state, the lower surface of the removed portion 4a is not substantially joined to the glass layer 5, and an adhesive tape (not shown) is pressed against the upper surface of the entire heating resistor 4 (the entire portion including the removed portion 4a). By peeling it off, only the removed portion 4a is removed so as to be peeled off by the adhesive tape, and as shown in FIG. 1 (c), the heating resistor 4 is placed on the glass layer 5 within the set width W ₁ described above. Will be left.

The reason why the removed portion 4a is easily peeled off by the adhesive tape as described above is that the photosensitive resin thin film 6 that burns at about 350 to 450 ° C. first shrinks before burning in the firing process of the heating resistor 4 described above. Then, the removed portion 4 on the upper part
A stress is applied to a so as to separate it from the main body of the exothermic low antibody 4 that should be left (this may cause cracks 7 to occur in the planned removal line portion), and burning of the photosensitive resin thin film 6 In the process (at this point, the heating resistor 4 is not yet completely burned), a so-called “lift-off effect” occurs due to the burning of the components of the photosensitive resin thin film 6 and weakens the removed portion 4a above it. Conceivable.
Further, it is necessary that the bonding force between the body portion of the heating resistor 4 and the glass layer 5 remaining on the glass layer 5 is larger than the bonding force between the body portion of the heating resistor 4 and the removed portion 4a. In this respect, the film thickness of the heating resistor 4 also becomes an important factor for peeling / removing, and as described above, the film thickness was found to be appropriate to be 20 μm or less according to experiments.

Further, the film thickness of the photosensitive resin thin film 6 is also an important factor for peeling / removing the removed portion 4a, and according to the experiment, it was found that the effect is small when the film thickness is 0.5 μm or less. Further, when the film thickness of the heating resistor 4 is reduced, the upper limit of the film pressure of the photosensitive resin thin film 6 also becomes a problem, and when the film thickness of the heating resistor 4 is, for example, 5 to 6 μm, If the film thickness of the photosensitive resin thin film 6 is not less than 2 μm,
Due to the above-mentioned "lift-off" action, there is a possibility that the end of the main body portion of the heating resistor 4 that should be left may be skipped together with the photosensitive resin thin film 6.

Further, if the upper layer of the glass layer 5, that is, the side of the heating resistor 4 is the crystallized glass layer 5b as in the embodiment, the removed portion 4a becomes the glass layer 5b after the photosensitive resin thin film 6 is blown. Even if they come into contact with each other, unlike the amorphous glass, there is no fear that they will diffuse and strongly bond to the removed portion 4a, which is convenient. Of course, even if the glass layer in contact with the heating resistor 4 is amorphous glass, the present invention can be applied. According to experiments, in this case, a part of the free end of the removed portion 4a is a very small amount, rarely glass. Although it remains on the layer, it can be completely removed by the step of retrying the adhesive tape, etc. Further, in the first place, a part of the free end of the removed portion 4a remains in a very small amount so that a small amount is left between the adjacent common electrodes 2 and 2 described above. Since it does not extend over the distance, there is no practical problem.

(Experimental Example 1) As in the above-described embodiment, the material, the method, and the dimensions of the above-described embodiment are obtained by depositing the crystallized glass layer 5b on the upper layer and the amorphous glass layer 5a on the lower layer on the substrate 1. After depositing the electrodes with, a photosensitive resin, [OMR8 manufactured by Tokyo Ohka Kogyo Co., Ltd.
3] was used to form the photosensitive resin thin film 6 with a thickness of 1 μm.
A thin groove window 6a having a width of 0.3 mm was formed on the photosensitive resin thin film 6, and a RuO ₂ -based resistance paste was applied by screen printing, and baked at 870 ° C. The thickness of the heating resistor 4 is 10
.mu.m, the width of each of the removed portions 4a was set to 0.1 mm. After this, peel off the removed portion 4a with adhesive tape.
When removed, a strip-shaped heating resistor 4 having substantially straight long sides was formed as shown in FIG. The linear portion of this low-pyrogenic antibody 4 is within ± 5 μm or less from the desired reference line, and exhibits extremely good linearity. When thermal printing was performed using this thermal head, the dots were arranged in a very good manner. It was confirmed that the data was obtained.

(Experimental Example 2) The film thickness of the photosensitive resin thin film 6 is set to 1.5 μm, and the heating resistor 4 is used.
As a result of performing a trial production in the same manner as in Experimental Example 1 except that the film thickness of 15 is set to 15 μm, the linear portion of the heating resistor 4 which is also left is within ± 5 μm from the desired reference line, and good heat is generated. Print data was obtained.

〔The invention's effect〕

As described above, according to the present invention, it is possible to form a straight line on both sides of the long side of the strip-shaped heating resistor by a manufacturing method suitable for mass production, and a shape in which each heating area for one dot is evenly arranged. Therefore, it has an effect of greatly contributing to the improvement of the print quality.

[Brief description of drawings]

1 and 2 relate to an embodiment of the present invention, and FIGS. 1 (a), (b), and (c) are schematic cross-sectional views of a main part for explaining a manufacturing process, and FIG. FIG. 3 is a plan view of an essential part showing a conventional example. 1 ... Substrate 2 ... Common electrode 3 ... Individual lead electrode 4 ... Heating resistor 4a ... Removed part 5 ... Glass layer 5a ... Amorphous glass layer 5b ... Crystallized glass layer 6 ... Photosensitive Thin resin film 6a ... Slit window

Claims (5)

[Claims] 1. A step of depositing a photosensitive resin thin film on a substrate on which a glass layer is deposited, and a step of exposing and etching the photosensitive resin thin film to meet a preset shape of a strip-shaped heating resistor. A step of forming a narrow groove window, a step of printing the resistance paste on both sides of the narrow groove window and the long sides of the narrow groove window and drying, and burning the photosensitive resin thin film, A method of manufacturing a thermal head, comprising: a step of firing the resistance paste; and a step of removing a portion of the fired resistor that is outside the narrow groove window in the fired resistor. 2. The film thickness of the photosensitive resin thin film is 0.5 to 2 .mu.m.
m, and the film thickness of the heating resistor is 5 to 20 μm. The method of manufacturing a thermal head according to claim 1, wherein the film thickness is 5 to 20 μm. 3. The method for manufacturing a thermal head according to claim 1, wherein the average width of the removed heating resistor portion is 0.05 mm or more. 4. The method of manufacturing a thermal head according to claim 1, wherein the removed heat generating resistor portion is removed by an adhesive tape. 5. The thermal head according to claim 1, wherein the glass layer on the substrate is a crystallized glass layer at least in a portion in contact with the heating resistor. Production method.