JP2757378B2 - Heating resistor forming method for thermal head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention (1) Field of Industrial Application The present invention relates to the heat generation of a thermal head for a thermal recording device used in a thermal printer or facsimile as an output device of a word processor, a personal computer or the like. The present invention relates to a method for forming a resistor.

(2) Conventional Technology Conventionally, as the thermal head, there is a so-called thick-film thermal head in which a plurality of common electrode connecting portions and individual electrodes arranged in a staggered manner are connected by a band-shaped heating resistor. In this thick film type thermal head, the heating resistor is usually formed by a conventionally known thick film forming technique using screen printing. However, in the thick-film type thermal head, since the common electrode connection portion and the individual electrodes are arranged in a staggered manner, it is necessary to form both of these electrodes at a density twice as high as the print dot density. It has been difficult to improve the printing resolution by increasing the dot density.

In order to solve the above-mentioned problem, a so-called thin-film thermal head has been known in which a plurality of common electrode connecting portions and individual electrodes disposed to face each other are connected by a plurality of heating resistors. According to this thin-film thermal head, since the electrodes need only be formed at a density equal to the print dot density, the print dot density can be increased. In this thin-film thermal head, the heating resistor is usually formed using a conventionally known thin-film forming technique. However, in this thin film forming technique, a resistive layer is formed on the entire surface of an insulating substrate by vacuum deposition or sputtering, and a resist layer having a resister forming pattern is formed on the resistive layer surface by photolithography, followed by etching. Since a plurality of heat generating resistors are formed, there is a problem that not only the manufacturing equipment becomes large but also the number of manufacturing steps is large as compared with the case where the heat generating resistors are formed using the conventional thick film forming technique.

In order to solve the above-described problems when the heating resistor is formed by the thick film and thin film forming methods,
For example, there is a method of forming a heating resistor using a printing technique as disclosed in JP-A-53-55039. In this method, a plurality of resistive element forming openings of a resist layer are filled with a resistive layer forming paste by printing, and then dried to form individual resistive layers in each of the openings. The layer is fired to form a plurality of heating resistors on the surface of the insulating substrate. According to this forming method, a heating resistor having a raised surface peripheral portion can be obtained.

In addition, as another source for solving the above problems, the 8A
FIG. 13 to FIG. 13 propose a method of forming a heating resistor using a printing technique such as excitation. Next, the outline of the formation method will be described.

8A and 8B, a common electrode 01 having a plurality of common electrode connection portions 01a arranged in the main scanning direction X at appropriate intervals, and a predetermined interval from each of the connection portions 01a. First, a resist layer 05 having a plurality of resistor formation openings 04 is formed on the surface of an insulating substrate 03 on which a plurality of individual electrodes 02 arranged opposite to each other are formed. Next, as shown in FIGS. 9A and 9B, a resist layer forming paste is printed on the surface of the resist layer 05 along the row of the openings 04, and the paste is applied to the openings 04 more than the surface of the resist layer 05. The filling is performed so that the height of the resistive layer is higher than that of the resistive layer. This wrapping step
This is performed as shown in FIGS. That is, the lapping tape T fed in the direction of arrow A by the pressing roller R and the feeding means (not shown) is used to
The resistance layer 06 is wrapped by pressing against the surface. in this case,
The wrapping tape T is attached to the insulating substrate 03 together with the pressing roller R.
Is reciprocated in the sub-scanning direction Y at a predetermined speed,
The insulating substrate 03 is reciprocated in the main scanning direction X at a predetermined speed.

At the time of the lapping, since the resistance layer 06 is formed higher than the surface of the resist layer 05 forming the resist pattern, for a while after the start of the lapping, a portion of the resistance layer 06 higher than the surface of the resist layer 05 is formed. Be ground. Then, when the lapping progresses and the surface heights of the resistive layer 06 and the resist layer 05 become the same (see the two-dot chain line in FIG. 10), the unsintered resistor 07 is formed in each of the openings 04. Is done. When lapping is continued thereafter, the resist layer 05 is also ground together with the unsintered resistor 07.

When the resist layer 05 and the unsintered resistor 07 are ground together, if the lapping resistance (grinding resistance) of the resist layer 05 is smaller than that of the unsintered resistor 07, the resist layer 05 Since the grinding speed is higher than the grinding speed of the green resistor 07, it is ground as shown by the solid line in FIG.
In this case, the surface of the unsintered resistor 07 formed in each of the openings 04 after the completion of the lapping is finished in a curved shape with a slightly raised central portion.

When the resist layer 05 and the non-sintered resistor 07 are ground, if the lapping resistance of the resist layer 05 is greater than that of the unsintered resistor 07, the resist layer
Since the grinding speed of 05 is lower than the grinding speed of the green resistor 07, it is ground as shown in FIG. 11, so that each green resistor 07 formed in each opening 04 after the lapping is completed. The surface is finished in a shape having a protrusion on the periphery.

After the completion of the lapping operation on the resistance layer 06 and the non-sintered resistor 07 as described above, the non-sintered resistor 07 in the opening 04 is sintered and the resist layer 05 is
Is removed to form a plurality of heating resistors on the surface of the insulating substrate 03.

(3) Problems to be Solved by the Invention Incidentally, each of the heating resistors formed by the heating resistor forming method using the above-described printing technique has a protrusion or a projection on the surface thereof. The protrusions or protrusions are small and are of such a degree that they could not be noticed in the past.However, when thermal recording paper is pressed against such a heating resistor having protrusions or protrusions on the surface, thermal printing is performed. In addition, the recording paper is not evenly hit against the surface of the heating resistor. For this reason, fading is likely to occur in printing, and a difference in resistance value occurs between the central portion and the peripheral portion of the heating resistor.
There has been a problem that color unevenness occurs in printing and it is difficult to perform thermal printing on thermal recording paper clearly. Further, the surface of the heating resistor is coated with a wear-resistant layer, but if a heating resistor having a protrusion on the peripheral edge of the surface is coated as shown in FIG. There is also a problem that the layer becomes thicker, which increases the heat capacity and increases power consumption.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to form the surface of a heating resistor to be flat.

B. Configuration of the Invention (1) Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a method for forming a plurality of openings for forming a resistor and a peripheral portion thereof in a resist layer formed on a surface of an insulating substrate. The filled resistance layer forming paste is dried to form a resistance layer, the resistance layer is wrapped to form a green resistor in each of the openings, and then the green resistor is fired. A method of forming a heating resistor for a thermal head, comprising removing the resist layer and forming a plurality of heating resistors on the surface of the insulating substrate, wherein a lapping step is provided after firing the unsintered resistor to make the surface flat. The above-mentioned heat generating resistor is formed.

(2) Function In the present invention, after sintering the unsintered resistor formed using the lapping step and removing the resist layer, the lapping step is further provided, so that the surface of the heating resistor is formed very flat. can do.

(3) Embodiment One embodiment of a method for forming a heating resistor of a thermal head according to the present invention will be described below with reference to FIGS. 1A to 7.

First, as shown in FIGS. 1A and 1B, a band-shaped common electrode main body portion 4a and a main electrode portion 4a are formed on the surface of an insulating substrate 3 in which a glaze thermal resistance layer 2 is formed on the surface of a substrate main body portion 1 made of alumina ceramic. Numerous common electrode connections extending from 4a in a comb shape
A common electrode 4 having a common electrode 4b and a large number of individual electrodes 5 arranged opposite to the common electrode connecting portion 4b at a predetermined interval are formed.

Next, as shown in FIGS. 2A and 2B, a photoresist is applied to the surface of the insulating substrate 3 on which the common electrode 4 and the individual electrode 5 are formed, and a mask (not shown) is covered, and then exposed and developed. As a result, a resist layer 7 having a large number of resistor forming openings 6 is formed.

Next, as shown in FIGS. 3A and 3B, a paste for forming a resistance layer is printed in a strip shape along the row of the openings 6 for forming the resistor, and the paste is formed so as to be higher than the surface of the resist layer 7. Each of the openings 6 for forming a resistor is filled. Subsequently, the resistor layer forming paste is dried to form a belt-shaped resistor layer 8. In this embodiment, the resist layer 7 is a resistive layer 8
It is formed from a material having a higher lapping strength (grinding resistance) than that of the material.

Next, the resistance layer 8 is wrapped. This lapping process is performed in the same manner as in the above-described conventional example shown in FIGS.

By the way, at the time of the ramping step, a wrapping tape T whose number indicating the abrasive grain roughness is # 1000 to # 3000 is used. The number of the lapping tape T is determined by a balance between the time required for lapping and the degree of finishing of the lapping surface (ground surface). For example # 1000
Using wrapping tape T (with abrasive grains) reduces lapping time, but the lapping surface is rough and finished, and # 3000 wrapping tape T (thing with fine abrasive grains)
When is used, the lapping time becomes longer, but the lapping surface is finished smoothly. Then, after rough lapping is performed for a predetermined time using a wrapping tape T of # 1000,
If the final lapping is performed using the lapping tape T of 00, it is possible to finish the lapping surface smoothly while shortening the lapping time.

Since the resistance layer 8 is formed higher than the surface of the resist layer 7 during the above-described lapping step, a portion of the resistance layer 8 higher than the surface of the resist layer 7 is ground for a while after the start of the lapping. When the lapping progresses and the surface heights of the resistive layer 8 and the resist layer 7 become the same, the resistive layer 8 is divided into unsintered resistors 9 in the respective resistor forming openings 6. Thereafter, when the lapping is continued, the resist layer 7 is also ground together with the unsintered resistor 9.

When the resist layer 7 and the unsintered resistor 9 are ground together, the resist layer 7 has a higher lapping resistance than the unsintered resistor 9, so that the center of the unsintered resistor 9 is Lapping is performed while being cut so as to be lower than the surface height of the resist layer 7. When the lapping is completed, as shown in FIGS. 4A and 4B, protrusions 9a are formed on the peripheral edge of the surface of the unsintered resistor 9 in each opening 6 of the resist layer 7.

Next, as shown in FIGS. 5A and 5B, the insulating substrate 3 on the surface of which the resist layer 7 and the large number of unsintered resistors 9 and the like are formed is placed in a sintering furnace (not shown) and heated. 7 is removed from the substrate 3 by burning, and the unsintered resistor 9 is fired to form a plurality of sintered resistors 10 at predetermined positions on the substrate 3. As shown in FIG. 5B, the sintered resistor 10 has a projection 10a on the periphery of the surface.

Next, the surface of the sintered resistor 10 is wrapped in the same manner as the above-described lapping process of the resistance layer 8 and using the same lapping device. Then, the protrusion 10a is removed,
A plurality of heating resistors 11 having a flat surface are formed on the surface of the insulating substrate 3. Heating resistor 11 formed as described above
Have a uniform surface height (thickness),
Therefore, there is no variation in the resistance value between the heating resistors 11.

Next, as shown in FIG. 7, the surface of the heating resistor 11 is coated with an abrasion-resistant layer 12 made of glaze. In this case, since the surface of the heating resistor 11 is flat, the wear-resistant layer 12 is coated with a constant thickness.

According to the above-described embodiment, since the lapping step is provided after the resist layer is removed so that the surface of the heating resistor 11 is flattened, the lapping step is performed before the resist layer is removed. Therefore, it is not necessary to prepare a new device for flattening the surface of the heating resistor 11.

As described above, one embodiment of the method of forming a heating resistor of a thermal head according to the present invention has been described in detail. However, the present invention is not limited to the above-described embodiment, but deviates from the present invention described in the claims. Various small design changes can be made without doing so.

For example, in the present embodiment, an example in which the resistance layer 8 is ground with the wrapping tape T during the lapping step has been described, but an appropriate grinding means other than the wrapping tape T can be used.

C. Effects of the Invention According to the above-described present invention, the resist layer is removed by firing the unsintered resistor having a very small surface protrusion or protrusion formed using the lapping step, and then further performing the lapping step. Provided. In the first lapping step, the protrusions and protrusions on the surface of the green resistor are very small, so that in the subsequent lapping step, the surface of the heating resistor can be formed very flat in a short step. it can. Therefore, it is possible to perform clear thermal printing on the recording paper without causing a variation in the resistance value between the heating resistors and preventing the thermal recording paper from hitting the paper against the heating resistors. When the surface of the heating resistor is coated with a wear-resistant layer, the wear-resistant layer can be coated with an appropriate constant thickness.

[Brief description of the drawings]

1A to 7 are views showing a procedure of an embodiment of a method of forming a heating resistor of a thermal head according to the present invention, and FIGS. 8A to 11 are procedures of a conventional method of forming a heating resistor of a thermal head. FIG. 12 and FIG. 13 are explanatory views of a lapping step of the heating resistor. 3 ... insulating substrate, 6 ... opening for resistor formation, 7 ... resist layer, 8 ... resistance layer, 9 ... unsintered resistor, 11 ...
Heating resistor

Claims (1)

(57) [Claims] 1. A resistive layer forming paste filled in a plurality of resistive element forming openings (6) of a resist layer (7) formed on the surface of an insulating substrate (3) and a peripheral part thereof is dried to form a resistive layer. Forming a layer (8), wrapping the resistance layer (8) to form a green resistor (9) in each of the openings (6), and then forming the green resistor (9); Baking the resist layer (7) and removing the resist layer (7) to form a plurality of heating resistors (11) on the surface of the insulating substrate (3). (9) A method for forming a heating resistor for a thermal head, wherein a lapping step is provided after baking to form the heating resistor (11) having a flat surface.