반복적인 굽힘에 따른 FBGA 메모리 모듈의 피로 수명 예측

Abstract

In this research, the fatigue life of fine-pitch ball grid array (FBGA) solder joints in memory modules was predicted by the bending experiment and the finite element analysis. Four-point bending test was performed by JEDEC standard to determine fatigue life of a memory module with five packages. Finite element model of the memory module was developed and analyzed under various displacement levels by using direct integration method. Strain under cyclic bending was measured and compared with simulation results for validation of the finite element model of the memory module. A global-local modeling technique was used in finite element simulation to calculate the strain response of the solder joints, and Coffin-Manson equation was developed by experimental and simulation methods. Then, the fatigue life of memory modules was predicted under cumulative damage condition by using the Miner’s rule and compared with experimental results. Experimental results show that predicted fatigue life of the memory module matches with experimental results closely.