Intermediate strain rate dependant mechanical properties for lead-free solders

Lead-free solders have strain rate dependent mechanical properties. In this work we report the elastic modulus and yield strength of several lead-free solder alloys at different strain rates. They are SnAgCu (with Ag 1 to 4% and Cu at 0.5%, namely SAC105, SAC205, SAC305 and SAC405), SAC-X (X=In, Ni and Bi), SnCu, SnCu-X and SnAg alloys. The intermediate strain rate tests (10^-3-10¹ 1/sec) were conducted by using Nanoindentation continuous stiffness measurement (CSM) technique. For Sn3.8Ag0.7Cu solder alloy, the properties were studied at a range of strain rate from low strain rate (10^-3 ~10⁰ 1/sec) using uni-axial tensile test. The effects of strain rate on the stress strain behavior for leadfree Sn3.8Ag0.7Cu solder are presented. For all the tests conducted, the higher the strain rate the higher the elastic modulus and yield stress of the solder; the higher strain rate, the higher the yield stress.