フリップチップ接合用はんだ材のせん断特性

抄録

Shear test has been carried out with same solders as those used in the previous paper in order to investigate the relation between thermal fatigue life of flip chip joints and shear properties of several solders. Shear strength decreased as the temperature changed from 23°C to 100°C in almost solders. However, in the case of pure indium, shear strength decreased little by changing the temperature. Indium and indium based solders such as In-48Sn and In-3Ag showed an excellent ductility under the conditions employed in this study. Fractography demonstrated that the fracture was mainly caused by the creep deformation. It is found that the lower the creep strength of solders, the longer their thermal fatigue life. The fact that parameter γ/τ (steady state shear rate/steady state shear stress) at 23°C is proportional to the thermal fatigue life strongly suggests that the latter can be predicted from the former.