Analyze the Effect of Micro-Void in Package Solder on Stress Based on Monte-Carlo and Finite Element Method

The Monte-Carlo and finite element method were applied to analysis the stress of BGA package solders affected by micro-void defects. First, the size of the micro-void and its distribution were tested by computed X-ray tomography. The finite element model of BGA package was established by Abaqus finite element analysis software, and the Anand constitutive equation was used to describe the stress and strain response of solder joints to analyze the stress distribution. Based on the critical solder joint where stress was maximum, the parametric finite element model for the solder joint with stochastic distribution of micro-void size and position was established, and then to analyz the law of solder joint stress distribution combing with experimental results. The results show that the smaller the diameter of the micro-void was and the closer the micro-void get to the surface of solder joints, the larger the stress on the solder joints could be obtained.