Finite-Element Analysis and Multiobjective Optimization of Solder Joint Temperature Difference and Cooling Stress During PCBA Reflow Process

Abstract

A finite-element analysis model of a printed circuit board assembly (PCBA) was established. The model was subjected to a reflow soldering temperature profile to analyze the temperature distribution at the solder joint solidification moment and the cooling stress distribution at the end of the reflow soldering process. Validation experiments confirmed the accuracy of the simulation results. The response surface methodology (RSM) combined with the NSGA-II algorithm was employed to optimize the reflow soldering process parameters with the dual objectives of minimizing solder joint temperature difference and cooling stress. The results reveal uneven temperature distribution at the solder joint solidification onset and concentrated cooling stress due to the mismatch in thermal expansion coefficients. The optimized reflow soldering process parameters were determined as: soak time of 80 s, reflow time of 35 s, reflow temperature of $230~^{\circ }$ C, and cooling rate of $2~^{\circ }$ C/s. Simulation validation demonstrated that with the optimal reflow soldering process parameters, the solder joint temperature difference and cooling stress were reduced by $1.058~^{\circ }$ C and 1.245 MPa, respectively. The results of this study on the optimization of the reflow soldering process parameters of the PCBA have a certain degree of significance in guiding.