Matsushita Electric Industrial Co., Ltd.

Isamu Hiraoka

Hiroshi Hirayama

Yasuhiro Shindo

Isami Saito

Yukio Tsujimoto

Disclosed is a method of heat treatment of a low melting-point metal for production of spheroidal bodies formed of a low melting-point metal or alloy or heat treatment of the low-melting point metal coated on the surface of an electrode of a chip part. The method comprises the steps of placing a high boiling-point liquid, such as oil, into a tubular container disposed vertically and provided with a heater at an upper portion thereof, the high boiling-point liquid being provided with a temperature gradient ranging from a high temperature above the melting point of the metal to be subjected to heat treatment to a low temperature below the melting point thereof; and allowing the low melting-point metal or a low melting-point alloy per se or a material having the low melting-point metal or alloy on its surface to move from the high-temperature portion of the high boiling-point liquid; whereby the low melting-point metal or a low melting-point alloy per se or a material having the low melting-point metal or alloy on its surface is made to melt in the high-temperature portion and is cooled in the low-temperature portion, thereby allowing a melt or a molten portion to solidify.

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Akigawa, Japan

Isamu Hiraoka