PURPOSE: To apply wetting property to the solder base, and prevent oxidation when melting, by coexisting phosphorus in a solder base of which principal components are Pb and Sn or In, mixing with a specified content of phosphorus.
CONSTITUTION: As the solder base to be used, for example, Pb-Sn alloy, Pb-Sn-Ag alloy, Pb-Sn-Sb alloy, and Pb-In alloy may be useful. The coexisting conditions for phosphorus include the method of adding by forming mother alloy with one componet of the solder base, and the method of directly adding phosphorus into the solder base. The solder is melted so that the phosphorous content may be 2W 50ppm. In this method, oxidation of solder base may be prevented, the amount of intermetallic compound included between the joining face and the metal to be joined when joining may be restrained to a minimum, and drop of joining characteristics may be lessened.
HORI AKIO
HIRATE NAOYUKI
