The Effect of Electric-Thermal-Vibration Stress Coupling on the Reliability of Sn-Ag-Cu Solder Joints

The damage of the package structure, caused by the multi-stress coupling of various environmental factors, can lead to the failure of the electronic device. Therefore, through the finite element method, the reliability analysis of three kinds of lead-free Sn-Ag-Cu solders (SAC105, SAC305, SAC405) in ball grid array (BGA) packaging was conducted under the conditions of thermoelectric coupling and random vibration, respectively. The results indicate that, according to the modified Coffin–Mason model, SAC405 has the largest plastic strain range and the shortest fatigue lifetime under thermoelectric coupling. As a counterpart, SAC105 has the smallest plastic strain range and the longest lifetime. However, under random vibration load, by addressing the Miner linear damage rule, the empirical formula of Manson high cycle fatigue and Steinberg’s three band theory, the fatigue lifetime of SAC405 is the longest, which is twice as much as SAC105 and SAC305. Furthermore, based on the linear damage superposition approach, the fatigue lifetime is predicted as SAC305 < SAC105 < SAC405 under multi-stress coupling of electric, thermal and random vibration conditions. These results will provide theoretical support for improving the application reliability of packaging in complex environments.