Random vibration simulation and analysis of PoP solder joints with different structure parameters

This paper aims to examine the effect of relative structure parameter on stress under random vibration. Firstly, the PoP device and PCB was modeled by using ANSYS 12.0. Then, to explore the stress and strain distribution of PoP solder joints under random vibration loading, power spectrum analysis was performed for PCB assembly. Lastly, focusing on the bottom package structure size, various parameters such as solder joints diameter and height, PCB thickness, etc, were considered to see the effect on interconnect reliability. The results show that, the maximum stress of bottom package (SPBGA) occurs at the corners of the outer solder joints array, while for the top package (VFBGA), the maximum stress is located at the corners of the innermost solder joint array, and the maximum stress of top package is also the maximum stress of the global assembly, which indicates the critical solder joints is most prone to failure. In addition,it´s also found, the maximum stress at SPBGA critical solder joints increases with increasing SPBGA solder joint height and PCB thickness, while decreases with increasing solder joints diameter. Combination height of SPBGA molding compound and VFBGA solder joints is proportional to the maximum stress of top package while inversely proportional to the maximum stress of bottom package.