| 摘要 |
PROBLEM TO BE SOLVED: To effectively prevent the oxidation of the surface of solder alloy powder by forming an organic metallic compound of a metal in a solder alloy with a malonic acid on the surface of the solder alloy powder containing no lead. SOLUTION: A solder alloy powder mainly consisting of tin-zinc or tin-zinc- bismuth and containing no lead is used. The grain size of the solder alloy powder is 10-40μm, desirably, 20-40μm. The solder alloy powder mainly consisting of tin-zinc-bismuth and containing no lead is reacted with a vaporized malonic acid to form an organic compound of a metal in the solder alloy powder with the malonic acid on the solder surface. The temperature of reaction is made to 50-120 deg.C. The amount expressed in terms of malonic acid in the case that the organic metallic compound on the surface of the solder alloy powder is acid-extracted, is 0.01-1.0 wt.% of the whole solder powder. In this range, the oxidation in handling the solder powder is prevented and the generation of solder ball is suppressed, which are the protective film forming effect with the malonic acid. |
