Stress analysis and life prediction of the solder joints amounted on the PGA packaging structure in aerospace subjected to random vibration

Abstract

Currently, SoC (System on Chip) components have been widely used in the aerospace electronic products and the PGA (Pin Grid Array) has been considered as one of the typical packaging patterns. Obviously, with the increase of the I/O density, the characteristics of the SoCs are approaching to a large volume and a heavy weight, which caused a big challenge to the packaging reliability issues. It is reported that the solder joints of the PGA packaging structure are susceptible to the random vibration. Thus, the reinforcement methods of the PGA packaging structure should be researched. Firstly, the effects of the different reinforcement methods on the typical PGA packaging structure are discussed by using the FEA simulation. The maximum stresses and the locations of the solder joints are mainly concerned and pointed out directly. From the comparison of the simulation results, it is found that the maximum stresses of the solder joints are totally located at the outer corners of the PGA packaging structures under the random vibration condition. Although the influence of the reinforcement pattern on the modals of the PCB board is small, it is seen that the reinforcing effect on the maximum stress of solder joints is remarkable. The efficient approach to improve the solder joints reliability is reinforcing at the middles and the ends of the PGA packaging structure. After that, the optimal reinforcement pattern and the sealing method are determined. Furthermore, based on the analysis results of the optimal reinforcement pattern, the classic Steinberg theory is employed to predict the life of the PGA packaging structure. It is obvious that the life of the solder joints is greatly prolonged compared to the one of the previous pattern. This approach can be recommended to solve the similar problems in the packaging industry.