Experimental and damage-coupled crystal plasticity constitutive study for solder ball under shear tests

The experimental and multi-scale numerical investigation for solder ball under shear loads is studied in the present work. Shear tests are conducted on Sn-1.0Ag-0.5Cu solder balls at temperatures of 25℃, 100℃, and 150℃, and velocities of 50 µm/s, 100 µm/s, and 200 µm/s, respectively. Analysis of the experimental data using the Gaussian regression approach is performed to investigate the impact of temperature and shear velocity on peak shear force. The dominated ductile fracture is then determined through analyzing fracture surface and shear force–displacement curve. Furthermore, a 2D crystal plasticity finite element (CPFE) model is proposed to illustrate the ductile fracture process of solder ball. The solder ball is postulated to be consisted of various oriented β-Sn grains, controlled by a developed damage-coupled crystal plasticity model at finite strain conditions. The validity of CPFE model is substantiated by comparing the modelling shear force–displacement curves with the corresponding experimental data. The results demonstrate that the proposed model can provide a satisfactory depiction of solder ball under shear test. The influences of damage parameters on stress–strain curve and damage evolution behavior are investigated. The evolution of damage variable and stress/strain distribution at different positions of solder ball under shear tests are discussed.