This study addresses the identification and improvement of a defect-reducing process step in plated-through-hole (PTH) technology of printed circuit board (PCB) assemblies. The process step discussed is a step in which the substrates are baked prior to assembly. While this step is developed to address defect problems faced by both OEMs and contract manufacturers alike, this paper discusses an experiment designed to improve the effect of the baking step that was performed at a PCB contract manufacturing facility. Furthermore, due to the tremendous variations in product complexity, a relatively new statistical process control chart which tracks defects per millions of opportunities (DPMO), was used to help evaluate the results.