JP3305764B2 - Method for manufacturing substrate for thermal head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a substrate for a thermal head of a thermal transfer printer. More particularly, the present invention relates to a method for manufacturing a substrate for a thermal head in which a glaze layer is formed on one or both surfaces of a ceramic substrate.

[0002]

2. Description of the Related Art In recent years, there has been a growing demand for improving the printing quality and increasing the printing speed of a thermal transfer printer. In order to meet this demand, it is essential for the thermal head substrate used in the thermal transfer printer that the surface of the glaze layer formed on the substrate surface should be smooth and free of undulations and defects, and it should be used together with the heating resistor. It is necessary to increase the contact with the thermal paper. For this reason, the formation part of the heating resistor of the glaze layer is formed as a convex ridge having a curved surface. As a method of forming such a ridged glaze layer, a glass paste is printed and baked on the entire surface of the ceramic substrate, and then a similar glass paste is printed and baked on a portion where the ridges are required. There is an indirect method of forming a ridge on the entire glaze layer. As another method, two types of glass pastes having different softening points are used. First, a glass paste having a high softening point is printed and baked on portions other than the ridge forming portions of the ceramic substrate. There is a direct method in which a glass paste having a low softening point is printed so as to have a desired height and fired to form a glaze having a ridge on the entire glaze layer. In addition, there is an increasing demand for high-definition printing and color printing, but in order to realize this demand, a convex with a small radius of curvature of preferably 5 mm or less is formed on the surface of a smooth glaze layer. In addition, it is necessary to reduce the undulation near the top of the ridge. For this purpose, a method in which the heat treatment step is performed twice has been used (for example, JP-A-2-44087).

[0003]

However, in the above-mentioned indirect method, the curvature of the ridge can be made relatively small, but the undulation near the top of the ridge is large, or the conductor must be finely wired on the ceramic substrate. On the other hand, the direct method has a feature that the conductor wiring can be formed on the surface of the smooth glaze layer and thus has few defects such as disconnection, but has a disadvantage that it is difficult to reduce the radius of curvature of the ridge. Also, in the method described in Japanese Patent Application Laid-Open No. 2-44087, the surface of the glaze layer is easily crystallized because of the two heat treatment steps, and the resistance value of the heating resistor formed on the surface of the glaze layer varies. Had become. An object of the present invention is to provide a method of manufacturing a thermal head substrate in which the surface of the glaze layer is less likely to crystallize and the resistance value of the heating resistor formed on the surface of the glaze layer is small. Another object of the present invention is to provide a method of manufacturing a substrate for a thermal head in which the waviness near the top of the ridge and the radius of curvature of the ridge are small and fine wiring of a conductor on a ceramic substrate is unnecessary. .

[0004]

As shown in FIG. 1 [SUMMARY OF THE INVENTION The present invention provides one or both sides Al ₂ O ₃ over the entire surface or surfaces partially smooth the -BaO-B ₂ O ₃ -CaO ceramic substrate 11
Forming an SiO ₂ -based glass glaze layer 12, leaving a part of the glass glaze layer 12 and removing the other part of the glass glaze layer, and forming a part of the remaining part on the ridge 13 to form the glass glaze layer 12; This is an improvement in a method of manufacturing a thermal head substrate in which a portion near the top of the ridge 13 is heat-treated at a temperature equal to or higher than the softening point of the glass to form a curved surface.
The characteristic configuration is that the heat treatment of the glass glaze layer is performed at a temperature rising rate of 40 ° C./min or more and 60 ° C. or more when the glass transition point or more.
/ Min or less and the maximum temperature is 1000 ° C. or more and 1200
° C or lower and the holding time at the maximum temperature is 10 minutes or more 2
0 minutes or less, and the cooling rate to the glass transition point after holding the maximum temperature is 40 ° C./min or more and 60 ° C./min or less.

The glass powder used as a raw material of the glass glaze layer formed on one or both surfaces of the ceramic substrate of the present invention contains Si, Ca, Ba, Al, and B as main components.
No. From this glass powder, Al ₂ O ₃ —BaO—B ₂ O ₃ —
Forming a glass glaze layer of CaO-SiO ₂ system. This
Glass glaze layer of Ru der which satisfy both insulating properties and heat resistance are required to the thermal head used in thermal transfer printers. As shown in FIG. 1 (a), a glass paste composed of a glass powder and a binder is adhered onto a ceramic substrate 11 by screen printing or spraying and fired to obtain a glass glaze layer 12 having a smooth surface. Subsequently, as shown in FIG. 1 (b), ridges 13 are partially formed on the smooth glass glaze layer 12 by dry or wet etching, polishing such as surface grinding, or the like. When forming the ridges 13 partially, the thickness of the glass glaze layer 12 to be removed by etching, polishing or the like needs to be smaller than the thickness of the glass glaze layer 12 first formed on the ceramic substrate 11. Further, as shown in FIG. 1 (c), the ridges 13 formed partially were added to the glass paste so that the viscosity thereof was 10 ^4.
At a temperature in the range of 10 ^6.5 poise, Figure 1 was heat-treated
The rectangular ridge 13 shown in (b) is rounded. The feature of the present invention lies in this heat treatment. Since crystals are likely to be generated on the surface of the glass glaze layer 12, the glass glaze
It is important that the heat treatment at a temperature equal to or higher than the glass transition point of the layer 12 is performed in the shortest possible time. Specifically, it is performed under the following conditions.

Al ₂ O ₃ —BaO—B ₂ O ₃ —CaO —Si
The temperature rise rate above the glass transition point of the O ₂ -based glass glaze layer is 40 ° C./min or more and 60 ° C./min or less, preferably 40 ° C./min or less.
It is not less than 50 ° C / min. Heating rate is 40 ° C /
When the temperature is less than 10 minutes, the surface of the glaze layer is easily crystallized. On the other hand, when the temperature exceeds 60 ° C./minute, the oxidation state of the metal element in the glaze layer changes and becomes unstable. Maximum temperature is 10
The temperature is from 00 ° C to 1200 ° C, preferably from 1000 ° C to 1100 ° C. If the maximum temperature is less than 1000 ° C., the glass powder in the glaze does not melt uniformly, while if it exceeds 1200 ° C., the surface of the glaze layer tends to crystallize, which is not preferable. The holding time at the maximum temperature is from 10 minutes to 20 minutes, preferably from 15 minutes to 20 minutes.
If the holding time is less than 10 minutes, it is difficult to fix the surface of the glaze layer in an amorphous state, while if it exceeds 20 minutes, the surface of the glaze layer is easily crystallized, which is not preferable. The cooling rate to the glass transition point after holding the maximum temperature is from 40 ° C./min to 60 ° C./min, preferably from 40 ° C./min to 50 ° C./min. If the cooling rate is less than 40 ° C./min, the surface of the glaze layer tends to crystallize, while if it exceeds 60 ° C./min, the surface of the glaze layer is hardly fixed in an amorphous state, which is not preferable.

[0007]

The heat treatment above the glass transition point is performed in the shortest possible time on the basis of the above conditions in order to make the convex stripes 13 of the glass glaze layer 12 round, so that no crystal is formed on the surface of the glass glaze layer 12. . This is because a metal element such as Ca, Ba, or Al, which is a constituent of the glass glaze layer 12, elutes and does not provide sufficient heat energy to crystallize and mature. As a result, the surface of the glass glaze layer 12 becomes smooth, and a sufficient heat storage effect can be obtained even when the heating resistor layer is formed on the ridges 13 of the glass glaze layer 12.

[0008]

The present invention will be described below in detail with reference to examples. The present invention is not limited by this embodiment. A ceramic substrate 11 having a length of 270 mm, a width of 50 mm, and a thickness of 1 mm and having an alumina content of 96% was prepared. A glass powder having a softening point of 855 ° C. (trade name: A
SF1760 (manufactured by Asahi Glass Co., Ltd.), ethyl cellulose, and terpineol are mixed to form a glass paste by screen printing to form a glass glaze layer 12. The glass glaze layer 12 is dried at 150 ° C.
It was baked at 0 ° C. for 30 minutes. The thickness of the glass paste was adjusted to be 60 μm after firing (FIG. 1 (a)). The glass glaze layer 12 has a width of 0.4 mm and a length of 270 mm,
A ridge 13 having a height of 0.04 mm was formed by surface grinding other than the ridge (FIG. 1B). Further, heat treatment was performed under the conditions of 12 shown in Table 1, and the ridges 13 were rounded. The surface of the glass glaze layer 12 after the heat treatment was observed with a microscope having a magnification of 100 to confirm whether crystals were formed on the surface. Table 1 shows the results. In addition,
When observed with a microscope, those which became white as compared with other portions of the glass glaze layer were regarded as having crystallization. (Hereafter, this page margin)

[0009]

[Table 1]

From the results in Table 1, it is found that the heat treatment conditions of Nos. 4, 8 and 12 corresponding to the examples do not crystallize the glass on the surface of the glass glaze layer as compared with the heat treatment conditions of other numbers corresponding to the comparative examples. You can see that.

[0011]

As described above, according to the present invention, the glass is formed on the surface of the glass glaze layer by performing the heat treatment after forming the ridges on the glass glaze layer under specific conditions in a short time. Does not crystallize. As a result, it is possible to manufacture a thermal head substrate having a glass glaze layer having a smooth surface without unevenness. In addition, it is possible to manufacture a thermal head substrate having a glass glaze layer having excellent insulating properties and heat insulating properties and having a large heat storage effect. In addition, when the heating resistor layer is formed on the ridge, a thermal head that does not require fine wiring of a conductive wire and has a small variation in resistance value can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a thermal head substrate showing the production of the thermal head substrate of the present invention in the order of steps.

[Explanation of symbols]

 Reference Signs List 11 ceramic substrate 12 glass glaze layer 13 ridge

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mitsuru Suda 2270 Yokoze, Yokoze-cho, Chichibu-gun, Saitama Prefecture Mitsubishi Materials Corporation Ceramics Research Laboratory (72) Koji Uchida 2270 Yokoze, Yuji-Yokoze-cho, Chichibu-gun, Saitama Mitsubishi Materials (56) References JP-A-3-175057 (JP, A) JP-A-3-251463 (JP, A) JP-A-3-251466 (JP, A) (58) Fields surveyed ( Int.Cl. ⁷ , DB name) B41J 2/335

Claims (2)

(57) [Claims] 1. An Al ₂ O ₃ —BaO—B ₂ O ₃ having a smooth surface on one or both sides of a ceramic substrate (11).
Forming a glass glaze layer (12) based on -CaO-SiO ₂ , removing a portion of the glass glaze layer (12) and removing the other portion of the glass glaze layer, thereby forming the remaining portion as a ridge (13); ), The glass glaze layer (12)
Heat-treated at a temperature equal to or higher than the softening point of the glass,
(13) In the method for manufacturing a substrate for a thermal head in which the vicinity of the top is processed into a curved surface according to (13), the heat treatment is performed at a rate of temperature rise above the glass transition point of the glass glaze layer of 40 ° C./min or more and 60 ° C./min or less. The holding time at the maximum temperature is 10 minutes or more and 20 minutes or less, and the cooling rate to the glass transition point after holding the maximum temperature is 4 minutes.
A method for manufacturing a substrate for a thermal head, which is performed at a temperature of 0 ° C./min to 60 ° C./min. 2. The method for manufacturing a substrate for a thermal head according to claim 1, wherein the maximum temperature at the time of heat-treating the glass glaze layer is from 1000 ° C. to 1200 ° C.