JPS596482B2 - How to form porcelain electrodes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming electrodes on ceramics for providing electrodes on the surface of ceramic semiconductors or the like by thermal spraying or the like.

Conventionally, as a method of forming ohmic electrodes on a ceramic semiconductor, a method of thermally spraying aluminum, zinc, soot, copper, brass, etc. onto the surface of a ceramic semiconductor is widely known.

By the way, as the applications of porcelain semiconductors expand (e.g., porcelain semiconductors are required to have a high level of dimensional accuracy in terms of their shape and dimensions, processing such as polishing and grinding after firing the porcelain becomes necessary.

However, even if the processed portion is thermally sprayed, the adhesive strength of the electrode will be reduced.

It was found that the cause of this was that the process-altered layer became brittle due to the accumulation of microcracks and distortions due to thermal shock during thermal spraying.

That is, as shown in FIG. 1A, a process-affected layer 2 in which crystals are destroyed due to processing is formed on the surface of the ceramic semiconductor 1, and metal is thermally sprayed onto this process-affected layer 2, as shown in FIG. 1B. When the electrode 3 is formed on the surface of the ceramic semiconductor 1, microcracks and distortions become large due to thermal shock during thermal spraying, and the process-affected layer 2 becomes extremely brittle.

Therefore, when performing a peel test, the electrode 3 can be easily removed as shown in Figure C.
peels off from the ceramic semiconductor 1.

Similar disadvantages occur, for example, in the case of electroless nickel plating on porcelain.

In view of the above points, the present invention provides a method for forming electrodes on porcelain that makes it possible to form electrodes with sufficient adhesive strength by re-firing the porcelain after processing to eliminate the process-affected layer and then providing the electrode on the porcelain. This is what we are trying to provide.

Hereinafter, a method for forming a ceramic electrode according to the present invention will be explained according to comparative examples and examples.

Comparative Example 1 A 3 mm thick barium titanate ceramic semiconductor substrate was prepared, and aluminum was sprayed onto the surface by arc spraying without any processing.

Then, adhesive tape (T-4000 manufactured by Sony Chemical ■) was applied to half of the surface of the sprayed electrode, and as a result of peeling off the adhesive tape and conducting a peel test, no peeling occurred on the electrode.

Comparative Example 2 A 3 mvtq barium titanate ceramic semiconductor substrate was prepared and finished to a thickness of 2.5 mm by lap polishing.

Aluminum was then sprayed onto the surface by direct arc spraying without re-firing.

Next, as a result of performing a peel test under the same conditions as Comparative Example 1,
The electrode was completely peeled off.

Comparative Example 3 A barium titanate ceramic semiconductor substrate with a thickness of 3 mm was prepared,
This was finished to a thickness of 2.5 mrn by lap polishing.

This polished substrate was heat-treated at 700°C for 5 minutes (
(refired).

Then, aluminum was sprayed onto the surface by arc spraying.

Next, as a result of performing a peel test under the same conditions as Comparative Example 1,
Most of the electrodes were peeled off.

Comparative Example 4 A barium titanate ceramic semiconductor substrate that had been processed in the same manner as in Comparative Example 3 was heat treated at 800° C. for 5 minutes, and then aluminum was sprayed onto the surface by arc spraying.

Then, as a result of performing a peel test under the same conditions as Comparative Example 1,
Most of the electrodes were peeled off.

Example 1 A barium titanate ceramic semiconductor substrate that had been processed in the same manner as in Comparative Example 3 was heat treated at 900°C for 5 minutes, and then aluminum was sprayed onto the surface by arc spraying.

Then, as a result of performing a peel test under the same conditions as Comparative Example 1,
Part of the electrode peeled off.

Example 2 A barium titanate ceramic semiconductor substrate that had been processed in the same manner as in Comparative Example 3 was heat treated at 1000° C. for 5 minutes, and then aluminum was sprayed onto the surface by arc spraying.

Then, as a result of performing a peel test under the same conditions as Comparative Example 1,
The electrode did not peel off.

Example 3 The heat treatment was performed at 1100° C., but the same results as in Example 2 were obtained.

Example 4 The heat treatment was performed at 1200'C, but the same results as in Example 2 were obtained.

According to the above embodiment, by re-firing the barium titanate-based ceramic semiconductor substrate for about 5 minutes and then performing thermal spraying,
It can be seen that the adhesive strength of the electrode can be improved.

That is, according to Example 1, the adhesive strength could be greatly improved to such an extent that only a part of the electrode was peeled off, and furthermore, according to Example 2,
According to samples 4 to 4, results equivalent to those of Comparative Example 1 in which no processing was performed were obtained.

That is, as shown in FIG. 2A, a process-affected layer 2 is formed on the surface of the ceramic semiconductor 1 in which the crystals are destroyed due to processing, but by re-firing, as shown in FIG. The process-affected layer 2 is removed by the thermal energy.

Therefore, even if the electrode 3 is formed by spraying metal onto the surface of the ceramic semiconductor 1 as shown in FIG. G
).

Therefore, according to the present invention, thermal spraying with a sufficiently strong adhesive force can be applied even to surfaces that have been subjected to severe abrasive processing, such as rapid grinding of porcelain with coarse powder.

Furthermore, in the past, it was necessary to preheat the surface to be sprayed during thermal spraying in order to soften thermal shock and increase strength, but this is no longer necessary, which improves work efficiency.

Furthermore, oxidation of the sprayed metal during heating was a problem;
Since you don't have to worry about that, you can choose from a wide range of metal types.

The method for forming electrodes on porcelain according to the present invention includes 1. metal spraying on porcelain. It is particularly effective in arc spraying, where the temperature of the porcelain body does not rise and the thermal shock is large, but it can also be effective in improving adhesive strength in electroless nickel plating, vapor deposition, ion blating, etc.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a conventional method for forming electrodes on porcelain, and FIG. 2 is an explanatory drawing showing a method for forming electrodes on porcelain according to the present invention. 1... Ceramic semiconductor, 2... Process-affected layer, 3... Electrode.

Claims (1)

[Scope of Claims] 1. A method for forming electrodes on porcelain, which comprises processing the porcelain and then re-firing it in a heat treatment at a temperature of 900° C. or more and 1200° C. or less, and then providing an electrode on the surface of the porcelain. 2. The method for forming electrodes on porcelain according to claim 1, wherein the porcelain is a barium titanate-based ceramic semiconductor. 3. The method for forming electrodes on porcelain according to claim 1, wherein the electrodes are provided on the surface of the porcelain by thermal spraying of aluminum.