Numerical Simulation of Impact Response of Board-Level Packaging Structure

Board-level drop responses are critical to evaluate the mechanical reliability of solder joints to serve as electrical and mechanical connections in electronic devices to resist failure due to drop impact. In this paper, by applying the elastoplastic constitutive models of solder materials and polymer materials in the BGA packaging structure, drop impact simulations of board-level packaging structure are performed according to the new version of JEDEC revised in 2016, JESD22-B111A for the drop test standard for portable electronic products. Particularly, the Input-G method is adopted, using a semi-sinusoidal acceleration pulse load with a peak of 1500G and a pulse time of 0.5 ms. The overall finite element model establishes a 1/4 model thanks to the symmetry of the board-level packaging structure. According to the simulation results, we explored the failure mode of the solder joint and polymer layer. At the same time, the mechanical reliability of different solder joints in the packaging structure is also discussed according to the production requirements. The results show that the solder joint far away from the center point of the PCB board is subjected to the greatest stress, which is the most vulnerable solder joint. It is found that the stress component in the vertical direction plays a leading role, which can be treated as the peeling stress. Peeling stress is the major reason to cause the crack occurrence and propagation in the solder joint, which is the main failure mode for solder joint. Under the same load, three BGA models with different solder joint distributions are compared.