Authors: Kong Hui Lee, Ph.D., George Oxx, & Mike Bixenman, Ph.D. Date Published: 5/19/2011
Abstract: The rapid implementation of lead-free alloys and miniaturization challenges assembly houses to improve yields and reduce costly defects. There are numerous challenges when converting production lines to lead-free. Three areas of concern are co-planar board finishes, noclean reflowed flux residues, and miniaturization. Thin layer PCB finishes readily corrode. Preserving the coatings that protect co-planar board finishes from oxidizing is critical to downstream yields, including rework. Flux changes impact cleaning due to greater residue, high molecular weight compounds, increased oxygen barrier, and halide-free. Higher packaging density exposes hardware to corrosive attacks as small components approach the size of corrosive metal migration. The purpose of this research paper is to present misprint cleaning process considerations learned from multiple designed experiments for preserving organic coatings over planar board finishes, removing process residues, and integrating with cleaning equipment.