OPTIMIZATION OF WELDING CONDITIONS FOR SOLAR CELL BUS BAR THROUGH EXPERIMENTAL DESIGN

This study is based on T Solar Cell Company. The company received customer complaints of the insufficient peeling strength caused by inappropriate welding processes, and these complaints later led to substantial compensation for customers. The company subsequently determined the optimized bus bar welding condition through the design of experiments (DOE) of the cell welding ribbon before mass production, which enabled the production line to further enhance their output yield after product launch. Because a solar cell module is expensive and not easy to rework, scrapping the entire solar cell module can cause high loss for a company. In the semiconductor industry, wafers and die units are extraordinarily costly; thus, DOE methodology can be applied to semiconductor industries to reduce process waste, improve output, and promote corporate competitiveness. In this study, the top three process factors affecting the quality of welding performance, namely iron welding temperature, heating-plate temperature, and welding time, were selected for DOE analysis, and each factor constituted three levels in the DOE construction. The results of statistical analysis revealed whether it had a normal distribution and referable value by verifying the results by employing an analytic model. The significance of the interactions between the three factors and between two factors was clarified. The effect of all three independent main factors on the output peeling strength was investigated. Subsequently, optimized welding conditions were determined using DOE analysis. Furthermore, a regression model was employed to prove the correlation between peeling strength and the solar cell module yield both before and after improvement. Suggestions for improvement made on the basis of the results of this study can be applied to corporate industries in the future for development and reference purposes in the solar cell industry. © 2022, Chinese Society for Quality. All rights reserved.