Sensitivity study of temperature and strain rate dependent properties on solder joint fatigue life

Tensile tests of 63Sn/37Pb solder were carried out at various strain rates over a wide range of temperatures to study the effect of strain rates and testing temperatures on the mechanical properties of solder. A statistical method incorporating multiple linear regression was also employed successfully and a set of empirical formulae was derived to describe the effects of temperature and strain rate quantitatively. These mechanical properties were applied to finite element analysis to study the sensitivity of these material properties on the fatigue life of solder joints in a plastic ball grid array (PBGA) package. From this study, the strain rate effect on solder response to different ramp rates during thermal cycling or thermal shock reliability tests can be modeled in finite element analysis.