Deformation behavior of solder alloys under variable strain rate shearing & creep conditions

Abstract

The rate-dependent deformation behavior of Sn3.8Ag0.7Cu Pb-free alloy and Sn-Pb eutectic alloy under constant and variable shearing strain rates and creep conditions was studied systematically with thin-walled specimens using a biaxial servo-controlled tension-torsion material testing system. The shearing tests were conducted at strain rates between 10 -6 /sec to 10 -1 /sec. Variable strain rate tests were also conducted for sudden strain rates change and stress relaxation to study the post-yielding flow stress dependency on stress. Shearing creep tests were carried at room temperatures under a variety of stress level. It is believed that such a fundamental study of deformation behavior of solder alloys under complex stress conditions is important to understand effects of soldering processes and microstructures on solder interconnect reliability, and also to implement sophisticated 3-D time-dependent nonlinear FEM analyses on electronic packages and assemblies.