A Comparison of Rapid Solidification Cast Versus Conventional Die Attach Soft Solders

Die attach soft solders manufactured by rapid solidification casting and by conventional methods were tested for several attributes and compared. Solders tested were Sn + 25%Ag + 10%Sb, Sn + 3.5%Ag, and Pb + 5%In + 2.5%Ag. Rapid solidification solders showed a much more refined structure than conventional solders, as well as exhibiting improved performance in wetting and mechanical strength tests. The results of our investigations showed that solder wettability was improved by about 15 percent for Sn + 3.5%Ag, to over 100-percent improvement for Sn + 25% Ag + 10%Sb and Pb + 5%In + 2.5%Ag. Solder joint shear strength was also improved by 75 percent or more for the solders tested. These results led to the conclusion that rapidly solidified Solders will yield improved performance.