SOLDER PASTE COMPOSITION, SOLDER PRECOATING METHOD AND MOUNTED SUBSTRATE

摘要

The present invention relates to a solder paste composition used for precoating an electrode surface with solder. A first solder paste composition is contains a solder powder and a flux, and a metallic powder made by metallic species different from metallic species constituting the solder powder and metallic species constituting the electrode surface in a rate of 0.1% by weight or more and 20% by weight or less based on a total amount of the solder powder. A second solder paste composition contains a deposition solder material which deposits the solder by heating and a flux, and a metallic powder comprising metallic species different from metallic species constituting a metallic component in the deposition solder material and metallic species constituting the electrode surface in a rate of 0.1% by weight or more and 20% by weight or less based on a total amount of the metallic component in the deposition solder material. When these solder paste compositions are evenly applied onto an electronic circuit substrate for precoating, such a solder that does not generate any swollen portion, solder-lacking portion and variability in a height thereof can be formed irrespective of a shape of a pad.