Drop/Impact Stress Analysis of Solder Joints in Board Level Electronics Package

A 3-D finite element model of board level BGA package was built and the Input-G method was used to analyze dynamic solder joint stress in the package during drop/impact.Boundary condition,bolt effects of the test board and peeling stress mechanism were emphasized in current investigation.An equivalent static model that can evaluate stress quickly was proposed.The results show that bolt constraints have a significant influence on the dynamic stress in solder joints.The bolt constraints must be treated as zero horizontal dis- placement in the area the bolt acted in the numerical model.The stress in the solder joint reaches its peak at 0.4ms and the maximum peeling stress is located at the most outer corner of the package.The peeling stress is dominated by the deflection of the PCB board.The equivalent static model predicts the same stress distribu- tion in the package but overestimates the stress about 23%.