Abstract: The finite element method was used to analyze the failure of solder joint for fine pitch flip chip assemblies under thermal shock ranging from -55 to 125℃. The fatigue life of critical solders was predicted based on Darveaux lifetime prediction model. The results show that the corner solder failed easiest, and the crack initiated in the solder along the accessory besides the chip, propagating from outside to inside. According to the average crack growth rate and accumulated plastic work density in solder joint, the parameters K₁, K₂, K₃, K₄ for Darveaux lifetime model were calculated to be 1 648.96, -0.234 9, 0.004 79 and -0.700 4 respectively, and the predicted fatigue life of the corner solder was 6171 cycles.