A Multiscale Modeling Method for the Creep Behavior of SnAg Solder Alloys

In this paper, a microstructure-dependent creep model is developed that accounts for the hierarchal microstructure at multiple length scales. The model considers three distinguishable phases in the solder alloy at two different length scales: at the larger scale Sn dendrites of micrometer size are embedded in a homogeneous eutectic phase; at a much smaller length scale the eutectic phase consists of submicron size Ag₃Sn particles embedded in a homogeneous Sn matrix. The model predictions agree well with creep test data of RE doped SnAg solders.