Abstract: A finite element model of chip scale package (CSP) solder joints is established, the paper also analyzes the residual stress and strain after reflow soldering. Put solder joint height, solder joint diameter, solder joint pad diameter and solder joints pitch as input parameters, and the maximum residual stress after reflow soldering as output parameter to analyze the sensitivity of the CSP solder joints. Select the factors that have significant influence on residual stress, establish neural network with momentum term prediction model and predict the residual stress of CSP solder joints. The results show that the significant factors affect the residual stress of the CSP solder joints are the solder joint diameter, solder joint pad diameter and solder joint pitch when the confidence is 95%. The order is solder joint diameter, solder joint pad diameter and solder joint pitch. The maximum relative error of the neural network with momentum term prediction model for prediction residual stress after reflow welding of CSP solder joints is 7.93%, the average error is 3.19%, which complete the accurate prediction of the residual stress.