A developed crystal plasticity model for viscoplastic mechanical behavior of SAC305 solder under thermomechanical coupled cyclic loading

Abstract

In the service of electronic products, owing to thermal cycling and external additional loads, solder joints undergo thermomechanical coupled cyclic loading. To fully understand the mechanical response of Sn-based Pb-free SAC305 solder in thermomechanical fatigue, a series of mechanical experiments with different strain amplitudes, phase angles of temperature and strain, and temperature ranges was performed. Simultaneously, a crystal plasticity model was developed that introduced a thermal activation term and temperature-dependent short-range back stress. The model could reasonably predict the stress–strain response under thermomechanical coupled cyclic loading, especially in a large temperature range. Meanwhile, the cyclic softening behavior of the solder was analyzed from multiple perspectives. Finally, the model was also used to predict the ratcheting strain accumulation process for materials with different orientation textures under thermomechanical coupled cyclic loading.