To provide a method where, at the time of working a lead-free soft solder alloy into fine solder powder, the flocculation of reaction products in a matrix of solder spherical matter is avoided, and alloy components are uniformly finely dispersed into the matrix of solder spherical matter.
A solder alloy is melted in vegetable and/or animal oil having high temperature stability. The melt is introduced into an another run down vessel for oil having a temperature higher than the liquid phase temperature at least by ≥20°C, is stirred therein, and is then subjected to shearing treatment for several times by a rotor and a stator, so as to form a dispersion composed of solder spherical matter and oil. The solder spherical matter is then separated by the following settling treatment, thus the alloy components are refined and are uniformly dispersed, and the fine solder powder is produced.
SCHULZE JUERGEN
Tsuneo Mihara
Okumura Yoshimichi
Blacksmith