Prediction of Variability in Vibration Durability of Oligocrystalline SnAgCu Solder Joints

SnAgCu solder joint has oligocrystalline (few large grains) structure and due to body-centered tetragonal (BCT) structure, each grain shows strongly anisotropic behavior. Modelling anisotropic behavior of grain scale solder joints has been extensively researched by this group. In this paper, anisotropic grain-scale plasticity model is used to predict variability of solder joint fatigue durability under sine sweep vibration excitation. Solder experiences different levels of cyclic stress for different grain orientations. Stress-based high cycle fatigue (HCF) model (Basquin’s model) and Miner’s rule are used for determining the variability of vibration durability of solder joints for different orientations and compared with experimental results.