Fatigue life estimation of FBGA memory device under vibration

This paper predicts the fatigue life of fine-pitch ball grid array (FBGA) solder joints in memory devices due to harmonic excitation through experiments and finite element analysis. Finite element models of the memory device with simplified solder joints and with detailed solder joints were developed as a global model and a local model, respectively. A global-local modeling technique was used in the finite element simulation to calculate the stress magnitude of solder joints in the memory device under vibration. Stress versus life (S-N) curve was generated for the memory devices under various vibration levels to derive the fatigue constants of solder material. The fatigue life of the memory device was then determined by using the Basquin equation and Miner’s rule. It was experimentally verified that the predicted fatigue life of the memory device under cumulative damage conditions matches the experimental results within reasonable accuracy.