Effect and experiment of screw locations on BGA viscoplastic fatigue life

This paper establishes a packaging module of multichip with lead-free solder ball SAC305. BGA solder ball adopt nonlinear Anand viscoplasticity constitute formula. With the change factor of five screw locations, the dangerous solder ball position and stress-strain hysteresis curve are obtained through simulation with applying thermal cycling condition and screw prestress under the IPC9701 standard. Based on Coffin-Manson equation, the fatigue life of dangerous solder ball and the trend curve of solder ball life with the screw locations are deduced. And through experiments, the conclusion of the simulation is verified.