Polyurethane conformal coating process for a printed wiring board

摘要

A cost-effective process for preventing mealing of a polyurethane conformal coating applied to a printed wiring board is described. The process includes utilizing a liquid photoimagable solder mask for protecting the circuitry within the board prior to applying the polyurethane conformal coating. The process further includes applying the polyurethane coating within a controlled maximum thickness of 0.0015 inches for preventing vesication of the conformal coating. Additionally, a manufactured printed circuit substrate incorporating these steps is described.