Multi-objective parameters optimization for stencil printing considering fluctuations in input factors

This research aims to establish a volume transfer efficiency (VTE) model of solder paste during stencil printing and achieve optimization of printing parameters to reduce manufacturing costs, scrap rate of printed circuit boards (PCBs), and environmental impact. Optimization models between VTE and printing parameters considering fluctuations in input factors have rarely been studied in solder paste stencil printing (SPSP). In this study, first, the optimization interval is proposed to be narrowed by fluctuation tolerance to improve the robustness of the optimization results. Then the response surface method (RSM) is used to find the nonlinear relationships between the VTE and the parameters of printing pressure, printing speed, separation speed, and separation distance. Next, the third-generation non-dominated sorting genetic algorithm (NSGA-III) is proposed to optimize the response model and obtain the best parameter combination. The optimal parameter combination obtained were 10.0 kg printing pressure, 10 mm/s printing speed, 1 mm/s separation speed, and 1.5 mm separation distance. Finally, to verify the validity of the model, mass production was performed with the optimal printing parameters, the process capability index C pm improved from 0.97 to 6.40, and the scrap rate of VTE decreased by 74%.