Multiaxial mechanical behavior of 63Sn-37Pb solder

Predicting solderability and the mechanical performance of complex solder joints requires constitutive equations that relate multiaxial stressing to the mechanical response of the solder. To address this need, the authors have investigated the effects of uniaxial tension and pure shear on the elastic, plastic, and fracture behavior of 63Sn-37Pb solder. Using standard tensile specimens, stress-strain curves were recorded at effective engineering strain rates between 0.0002 and 0.2 s ^-1. From these curves, young´s modulus, 0.2% offset yield strength, ultimate tensile strength, and elongation to fracture were determined. Using similar torsion specimens, tests to examine shear behavior were conducted. From these tests, shear modulus, shear yield strength, and ultimate shear strength were determined for effective strain rates between approximately 0.0001 and 0.02 s^-1. little or no effect of strain rate on Young´s modulus or shear modulus was observed. The plastic properties (yield and ultimate strengths) in both tension and shear are strongly rate dependent and agree with the von Mises multiaxial yield theory. Fracture behavior (e.g. ductility) is strongly rate dependent