Nippon Steel Corporation

Hisao Kuribayashi

Tomohiro Uno

Yasuhide Ohno

Osamu Kitamura

Yasuhiro Suzuki

Tadakatsu Maruyama

Tosiharu Kikuchi

A method of producing soft fine metal spheres for semiconductor packaging from a material selected from soft metals and soft alloys. A plurality of fine wires made of the material are arranged in parallel on a flat base plate. Each of the wires has a diameter of not more than 100 .mu.m. The fine wires are cut into wire chips having an equal mass relative to each other and a chip length/chip diameter ratio between 5 and 100 by utilizing a cutting jig having cutting edges which are arranged at a constant pitch. The resulting wire chips are arranged so that the chips are spaced apart a minimum distance sufficient to prevent the chips from merging when melted. The resulting spaced-apart wire chips are heated to a temperature up to but not exceeding 100.degree. C. above the melting point thereof, thereby forming the chips into molten spheres. The resulting molten spheres are cooled, thereby forming solid spheres having a diameter within about 5% of a desired diameter.

Growing community of inventors

Kitakyushu, Japan

Hisao Kuribayashi