Study on the volume effect of mechanical behavior of Cu/Sn/Cu microscale solder joints considering crystal anisotropy

Abstract

In order to investigate the mechanical behavior of microscale solder joints more accurately, the volume effect of mechanical behavior of line-type Cu/Sn/Cu solder joints under tensile load was investigated by finite element analysis (FEA) in this study. Considering the crystal anisotropy, the elastic constants C ij of β-Sn single crystal were served as the anisotropic material property and input into the FEA software. As a comparison, isotropic analysis of β-Sn was carried out based on the isotropic assumption. Simulation results demonstrate maximum von Mises stress and maximum damage equivalent stress increase with the increase of solder matrix height in both anisotropic and isotropic cases. In addition, the maximum values of the von Mises stress and damage equivalent stress considering crystal anisotropy are much larger than those based on the isotropic assumption. The position of maximum von Mises stress is always located near the outside area of the solder matrix with the increase of solder matrix height in both anisotropic and isotropic cases. The position of maximum damage equivalent stress is changed and closer to the center for a solder matrix with a larger height in the case of isotropy. Comparing to the isotropic results, the position of maximum damage equivalent stress is always situated near the outside of the solder matrix considering crystal anisotropy. The simulation results illuminate that the volume effect and crystal anisotropy have an obvious effect on the magnitude and distribution of von Mises stress and damage equivalent stress in the solder matrix.