DOE OPTIMIZATION OF SAC 305 LEAD-FREE WAVE SOLDERING AND SPRAY FLUXER USING SELECTIVE SOLDERING PALLET

摘要

Wave soldering, for the first time, a SAC 305 Lead-Free Alloy on a 12 layer, 0.092 inches thick board using a selective soldering pallet is no simple task. When switching from lead-tin eutectic wave soldering to lead-free wave soldering a good way to gain understanding of the process and process window is to perform a detailed Design of Experiment of the process parameters. This paper will detail the steps required to optimize the wave soldering process for lead-free wave soldering. Two statistically designed experiments were used for the optimization experiment. A Hardin-Sloane I-Optimal 4 factor matrix was used for the wave soldering factors using 18 trials [6]. A Hardin-Sloane I-Optimal 3 factor matrix using 13 trials was used to optimize the spray fluxer settings [6]. This paper will show how to utilize DOE techniques to achieve the optimal process window with minimal trials, cost and time for lead- free wave soldering. This paper will cover the response outputs of PTH solder hole fill and wetting showing cross- section results of both trials representing “bad” and “good” points in the matrix. This study generated very unique PTH solder voiding phenomena and will be studied using the DOE model and discussed. The sweet-spot optimum for the response factors will be shown demonstrating the power of DOE process optimization.