JPS59171191A - Method of printing thick film circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a method for printing thick film circuits using the drawing method 75.

Composition table of conventional example Problems Conventionally, the process of applying a thick film paste onto a substrate using a clean printing method or a drawing method must be performed in a constant temperature room (normal temperature fluctuation of 2 degrees Celsius or less). Is it common? This is done to prevent changes in coating thickness (particularly film thickness) caused by changes in the viscosity of thick film paste due to temperature changes, and as shown in Figure 1, the film thickness The screen printing method, which causes little change, has been effective. However, in the case of a drawing method in which thick film paste is discharged from a drawing nozzle by applying a constant pressure of 1 pressure to the thick film paste filled in a tank, the viscosity of the paste may fluctuate.
:The discharge roughness changes greatly, and as shown in FIG. 1, the film thickness also changes dramatically even when the viscosity changes due to a slight temperature change. In the conventional thermostatic chamber system that controls the ambient temperature, where the temperature fluctuations are relatively large, it is difficult to suppress the fluctuations in the paste film (7), and even if the nominal temperature fluctuation is 1°C, the actual paste temperature depends on the air flow. It is obvious that the measured paste temperature fluctuates by more than 3°C, which is influenced by many factors such as heat generated by the operation of the drawing equipment.
−) Noko. , therefore the drawing is done in a conventional constant temperature room -)
In this case, the paste film thickness varied by about 25 inches, making it difficult to obtain the desired feel.

OBJECTS OF THE INVENTION In view of the above-mentioned drawbacks, an object of the present invention is to provide a method for printing thick film circuits using a drawing method that allows uniform film thickness to be obtained and electrical characteristics to be stabilized.

Structure of the Invention The present invention involves a process of keeping the temperature fluctuation of a thick film paste within 1°C by circulating a liquid at a constant temperature around a paste reservoir, and a process of maintaining a thick film paste with a slight change in viscosity by stabilizing the temperature. It consists of a process of moving the ejecting drawing head relative to the substrate to apply a thick film paste on the surface of the substrate according to the desired pattern, and employs an unprecedented high-precision temperature control method using liquid circulation. This has the unique effect of reducing fluctuations in paste viscosity, stabilizing the paste film thickness during coating, and reducing variations in electrical characteristics.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Figure 2 shows the cross section of the drawing head and the liquid circulation path in an embodiment of the present invention, where 1 is a paste reservoir, 2 is a thick film paste, 3 is a constant temperature water circulation section, and 4 is a constant temperature water circulation section. In the apparatus, 5 indicates a drawing nozzle, and 6 indicates a float. Here, a constant temperature water circulation section 3 is provided around the outer periphery of the paste reservoir 1 filled with the thick film paste 2, and constant temperature water (25° C.±0.5° C. in the example) is circulated by a circulation device 4. . With this configuration, the temperature of thick film paste 2 is 24.5°C.
It is in the temperature range of ~25.5°C, and the temperature difference can be maintained at 1°C or less. This is because the thermal conductivity of water is extremely high compared to air, making it less susceptible to external temperature fluctuations and allowing highly accurate temperature control. As a constant temperature water circulation device, a combination of a constant temperature bath using a heater and a pump, a device combining a constant temperature mechanism using the Peltier effect and a pump, etc. can be used. Silicone oil is also used outside the water plate as a liquid (heating medium).

Higher alcohols can also be used.

Now, air pressure is applied to the thick film paste 2 in the temperature range of 24.6°C to 25.6°C via a float 6 provided to prevent solvent volatilization, and the thick film paste 2 is drawn from the drawing nozzle 6 through the X-Y The paste was discharged onto an alumina substrate 7 placed on a table (not shown), and the thick film paste was applied in a desired pattern by moving the X-Y table. Here, alumina substrate 7
The zero surface temperature was adjusted to 24° C. to 26° C. so that the temperature difference was 1.5° C. or less with respect to the thick film paste temperature.

This was done to prevent the thick film paste from changing its viscosity when it comes into contact with the alumina substrate, changing fluidity and changing the application state when the temperature difference between the alumina substrate and the thick film paste becomes large.

By stabilizing the temperature fluctuation of the thick film paste to 1° C. or less by circulating constant-temperature water as described below, the fluctuation in film thickness can be reduced to within 10%.

Effects of the Invention As described above, the present invention is capable of producing a paste by circulating a liquid at a constant temperature around the reservoir to maintain the temperature fluctuation of the thick film paste within 1°C, and then applying it onto a substrate. The film thickness can be stabilized and variations in electrical characteristics can be reduced, which has great practical effects.

[Brief explanation of the drawing]

FIG. 1 is a diagram comparing the relationship between paste temperature and film thickness between the screen IJ printing method and the drawing method, and FIG. 2 is a sectional view of the main part of the drawing head in one embodiment of the present invention. 1...Paste reservoir, 6...Drawing nozzle, 2
...Thick film paste, 6...Float,
3... Constant temperature water circulation unit, 7... Alumina substrate, 4... Constant temperature water circulation device.

Claims (1)

[Claims] A liquid at a constant temperature is circulated around the paste reservoir to maintain temperature fluctuations of the thick film paste within 1°C.4) A drawing head for discharging the thick film paste is moved relative to the substrate. A method for printing a thick film circuit which does not include the steps of applying a thick film paste on the surface of the substrate in a desired pattern.