JPS6229236B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a thermal head used in facsimiles, planters, etc., for thermally recording characters, figures, etc.

Conventionally, this type of manufacturing method is shown in Figures 1a to d.
The following were taken. That is, Figure 1a
As shown in FIG. 2, an organic film 2 of uniform thickness is formed on a predetermined area of the ceramic substrate 1, excluding the area where the resistor is planned, by thermocompression bonding or the like, and the resistor area surrounded by the organic film 2 is formed. The thick film resistor paste 3 is printed on the area using a screen printer and applied and filled as shown in FIG. 1b. Next, unnecessary portions of the thick film resistor paste 3 that are deposited higher than the surface of the organic film 2 are removed using a squeegee 4 shown in FIG. 1c, and then dried. After this drying, the organic film 2 is removed by means such as etching, and then the thick film paste 5 is fired at around 900°C.
A thick film resistor 6, that is, a heating resistor for thermal recording is formed (FIG. 1d).

By the way, in the conventional method of manufacturing a thermal head, the mutual adhesion coefficient at the joint between the organic film 2 and the thick film resistor paste 3 is high when the thick film resistor paste 3 is filled, and the thick film resistor paste 5 is In the third step of drying, the volume reduction of the thick film resistor paste 5 due to evaporation of the organic solvent contained in the thick film resistor paste 5 is unstable, and furthermore, in the fourth step of firing the thick film resistor paste 5. Due to unstable combustion of the organic binder contained in the thick film resistor paste 3, foaming, combustion residue, etc. occur on the surface of the thick film resistor 6. Therefore, the contact between the thick film resistor 6 and the thermal recording paper (not shown) that is fed and placed in contact with the surface of the thick film resistor 6 becomes uneven, resulting in uneven print density, uneven print dot size, etc. There were serious drawbacks as a thermal head, such as an increase in the power applied to the thick film resistor 6 and a deterioration in thermal response.

This invention was made in order to eliminate the above-mentioned conventional drawbacks. After drying the insulating substrate on which the organic film and thick film resistance paste have been applied and the unnecessary parts removed, the glass frit contained in the thick film resistance paste is removed. Pre-firing is carried out by gradually raising the temperature until it reaches around the softening temperature of To provide a method for manufacturing a thermal head that can print with low power and still provide good image quality.

An embodiment of the present invention will be described below with reference to FIG. In FIG. 2, first, as a first step, an organic film 2 is formed to a uniform thickness on a predetermined region of the ceramic substrate 1, that is, a portion other than the intended resistance region by means such as thermocompression bonding, as shown in FIG. 2a. , as a second step, a thick film resistor paste 3 is printed on the ceramic substrate 1 using a screen printer, and is applied to the resistor area surrounded by the organic film 2;
Fill (Figure 2b). Next, in the third step, unnecessary portions of the thick film resistor paste 3 are removed using a squeegee 4 and then dried (FIG. 2c). In other words, since the unnecessary parts of the resistor paste are removed before drying, even if the necessary parts are removed during the removal process and the surface of the resistor paste becomes uneven, it will be removed immediately after the resistor paste is applied.
It returns to its original state due to the surface tension of the resistance paste itself, allowing complete removal of unnecessary portions and maintaining uniformity of required portions. Next, as the fourth step, there is a forced air flow and the temperature rises at a gradual temperature rise curve of 10°C/min to 20°C/min, and the highest temperature is included in the thick film resistor paste 5. By pre-firing at a temperature below the softening temperature of the glass frit, the organic film 2 and the ethyl cellulose organic binder in the thick film resistor paste 5 are evaporated and burned to form the resistor 8 (FIG. 2d). Finally, as a fifth step, this pre-fired resistor 8 is fired at a temperature of around 900°C to form a thick film resistor 9 (second
Figure e). Commonly used thick film resistor paste 3
The temperature and volume reduction rate of the thick film resistor paste during drying and firing are shown in FIG. That is, the butyl carbitol-based organic solvent contained in the thick film resistance paste 5 evaporates at a temperature of 100°C to 200°C, and the ethyl cellulose-based organic binder contained in the paste evaporates at a temperature of 300°C to 400°C. The volume of thick film resistor paste that completes combustion at temperature is 60%~70%
drastically decreased. Further, the glass frit contained in the thick film resistor paste 5 begins to soften at temperatures between 500°C and 700°C.

Therefore, by the step of pre-baking the thick film resistor paste 5 (FIG. 2d), the thick film resistor paste 5 is
Since the organic solvent contained therein does not evaporate rapidly and the organic binder does not burn, the surface of the fired thick film resistor 9 is free from foaming, adhesion of combustion residue, etc., and has a good surface smoothness. Become. For this reason,
The printing density on the thermosensitive recording paper becomes uniform, printing can be performed with less power applied to the thick film resistor, and the thermal responsiveness of the thick film resistor improves, allowing high-speed printing.

This pre-firing also eliminates the problem of the adhesive coefficient at the joint between the organic film 2 and the thick film resistor paste 5, but in order to further enhance this resolving effect, as shown in FIGS. 3a to 3e, ceramic The first step (FIG. 3a) is to form the organic film 2 on the substrate 1. The second step (third step is to screen print, fill and apply the thick film paste 3 on the ceramic substrate 1.
Figure c) between organic film 2 and thick film resistor paste 3.
A step (FIG. 3b) of applying the adhesive material 10 to the joint portion may be added. Incidentally, it is a theory that this adhesive material 10 may be applied to the entire surface of the organic film 2 and the ceramic substrate 1.

Further, in order to prevent wear of the thick film resistor 9 due to sliding between the thick film resistor 9 and the heat-sensitive recording paper, a wear-resistant layer may be formed on and in contact with the thick film resistor 9.
Furthermore, after the thick film resistor 9 is formed, its surface may be polished to make the surface smoother more uniform.

As described above, according to the present invention, after forming an organic film and a resistive paste to a uniform thickness on predetermined areas on an insulating substrate, removing unnecessary portions of the resistive paste, and drying the resistive paste, the resistive paste is A pre-firing step is added in which the temperature is gradually raised to near the softening temperature of the glass frit contained in the resistor paste to evaporate and burn the organic film and the ethyl cellulose organic binder in the resistor paste, and then the main firing is performed. The smoothness of the surface of the fired resistor is improved, resulting in excellent image quality, low power consumption, and high speed recording.

[Brief explanation of the drawing]

1A to 1D are process diagrams for explaining the manufacturing process of a conventional thermal head, and FIGS. 2A to 2E are process diagrams for explaining the manufacturing process of a thermal head according to an embodiment of the present invention. 3a to 3e are manufacturing process diagrams showing other embodiments of the present invention, and FIG. 4 is a thick film paste volume-temperature characteristic diagram for explaining the operation of the present invention. In the figure, 1 is a ceramic substrate, 2 is an organic film, 3 and 5 are thick film resistor pastes, 9 is a thick film resistor, 1
0 is sticky material. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. A step of depositing and forming an organic film of uniform thickness on a portion of an insulating substrate other than the intended resistance area, and a resistor paste containing glass frit in the intended resistance area surrounded by the organic film. A process of depositing and filling the resistive paste, removing unnecessary parts of the deposited and filled resistor paste, forming the deposited thickness to be the same as the thickness of the organic film, and drying it. After this drying, A step of pre-firing the glass frit by gradually increasing the temperature until it reaches near the softening temperature of the glass frit. After this pre-baking, the glass frit is fired at a temperature higher than the softening temperature of the glass frit, and a resistor for thermal recording is placed in the area where the resistance is planned. A method for manufacturing a thermal head, which comprises a step of forming. 2. The method of manufacturing a thermal head according to claim 1, wherein an adhesive material is applied to at least the resistance paste bonding surface of the organic film formed on the insulating substrate.