Measurements of Inelastic Strain Evolution of Single Solder Grain Subject to Nominal Shear Loading

Abstract

A novel E-shaped symmetric configuration is proposed and implemented to document deformation evolutions of single-grain solder joints with different orientations. The configuration is fabricated from two metals with different coefficient of thermal expansions to produce precisely-controlled shear-dominant loading to solder joints when subjected to a thermal excursion. Cooling rates during solder solidification are controlled to produce joints with a large single grain of Sn-based Pb-free solder. Moire interferometry is employed to measure the detailed in-situ deformations of single grain solder joints during a thermal cycle of −40 °C to 125 °C. The results are analyzed to provide the history of grain orientation-dependent inelastic strain evolutions. The results are aimed at calibrating and verifying the anisotropic constitutive models developed for Sn-based Pb-free solder alloys.