抄録
Lead free solder materials have been widely used for the electric circuit board. The solder joints are subjected to fatigue damage under cyclic load and creep damage under long term load. And it was known that the interaction between fatigue damage and creep damage shorten the life of solder joint. In this study, fatigue tests were carried out for Sn-3.0Ag-0.5Cu solder material at an elevated temperature varying the strain rate from 1×10^<-4>/s to 1×10^<-2>/s. As the result of tests, the life of low cycle test became longer as the strain rate is faster, and it was almost saturated at 1×10^<-3>/s. On the other hand, it discussed why the life of 1×10^<-4>/s is shorter than that of 1×10^<-3>/s from the view point of the interaction between creep and fatigue damage. As the result of discussion, the creep damage recovery under compressive stress should be counted not only fatigue damage or creep damage under tensile stress.
