PURPOSE: To eliminate the scattering phenomenon of a solder and flux and to perform a good soldering by selecting the liquid which has low hygroscopic property as the solvent in the flux of paste shape and shows the behavior accorded with the aim in the temp. rising process.
CONSTITUTION: In case of soldering an electronic component, etc., the liquid having low hygroscopic property, causing no decomposition nor combination at less than the melting point of a solder and having the temp. at which an abrupt evaporation is started being higher than the melting point of the solder is selectively used as the solvent in the flux of paste shape. As for this liquid, more than one kind of the aromatic group organic heating medium of an alkyl benzene, alkyl naphthalene, etc. is used. The compounding quantity of this liquid is taken more than about 25wt% of the total solvent quantity in the flux of paste shape. The soldering is performed with a laser reflow method, etc. by using this solder paste. This method is suitable for the soldering of high precision and high accuracy.
UEHARA HARUO
NISHIMURA TETSUO
KATSUMURA SHINSUKE
NIPPON SUPERIASHIYA KK