Abstract: Focusing on Ball Grid Array Package(BGA) solder joints within microsystem packaging structures, this study investigates the factors affecting fatigue life prediction using the Darveaux model under thermal cycling loading conditions. Through finite element analysis, it separately investigates the impact of crack growth correlation coefficients, viscoplastic strain energy density increments, and fracture characteristic lengths on the predictive accuracy of the Darveaux model. This study reveals the current inadequacy in considering influential factors when applying the Darveaux life model in solder joint reliability research and provides relevant recommendations for addressing these factors. Furthermore, employing a Monte Carlo sampling-based global sensitivity analysis method, it studies the sensitivity of fatigue life to material parameters within the Darveaux model under different fracture characteristic lengths. The research findings serve as a valuable reference for accurately predicting the thermal fatigue life of microsystem packaging structures under thermal cycling loads using the Darveaux model. They offer rational suggestions and a reference framework for determining these critical factors. This revised translation maintains the technical content while enhancing fluency and accuracy.