Numerical simulation and fatigue life estimation of BGA packages under random vibration loading

• The greater the random vibration loading imposed on the PCB assembly, the shorter the fatigue life of BGA will have.
• When screws fixing PCB assembly become looser, the PCB assembly is more likely to be damaged.
• The fatigue life of BGA solder joints under random vibration loading is determined Based on Miner's rule and random vibration theory.

This work investigates finite element (FE) simulation and fatigue life prediction of ball grid array (BGA) under random vibration loading. The printed circuit board (PCB) assemblies are tested under random vibration loadings. The center displacement responses of PCB assemblies and the time to failure are recorded. A three-dimensional FE model of the PCB assembly is established using ABAQUS software, and spectrum analysis specified for random vibration is performed numerically to obtain the response power spectral density (PSD) of the PCB assembly. Simulation results show good correlation with experimental data in terms of center displacement responses in actual random vibration testing, validating the effectiveness of the proposed FE model. In particular, the root mean square (RMS) values of the maximum peeling stress under different loading conditions are calculated and compared. Different pre-tightening force levels and vibration intensities are applied to study their influence on solder joint reliability. Finally, the fatigue life of BGA solder joints under random vibration loading is determined in terms of Miner's rule and random vibration theory, and it is experimentally verified that the predicted fatigue life of BGA solder joints matches the experimental results with reasonable accuracy. It is concluded that solder joints at the four outermost corners of BGA packages have higher peeling stress values than others, especially at the both sides of solder joints near PCB and BGA. The stress responses of critical solder joints increase with the increase of vibration loading. BGA packages would be more prone to damage and failure when the screws became looser. This research will provide a guide for investigating the dynamic characteristics and optimization design of PCB assemblies, and predicting the fatigue life of BGA solder joints.