EXPERIMENTAL STUDY OF THE WORKPIECE LEVEL VARIABILITY IN THROUGH-HOLES ELECTROPLATING

摘要

The acid copper plating of plated-through holes (PTHs) was studied by statistical experiments. The objectives of this study were to investigate the effects of process and product parameters on the workpiece level uniformity, and to explore the minimization of the deposit thickness variation. The parameters studied were the concentration of copper sulphate and sulphuric acid, average current density (ACD), electrode separation (ES), and the aspect ratio (CAR). Multifactor two-level factorial and the central composite rotatable five-level experiments were designed and conducted sequentially to generate statistical process models. The optimum values of ACD and ES, and the minimum variability achievable were found to increase with the corrected aspect ratio of the through-hole. Post-optimal analysis showed that the sensitivity of the optimum solution toward ACD was 2.5 times higher than the ES in PTH plating.