Typically , the problem we found using LPI on via holes is not removing the residual LPI from the holes during the developing process . This problem occurs randomly and I believe it is resulting from the pressure variabilites in using the hand squeegee process for applying the LPI. This should be corrected by using automatic screening equipment which would provide a more consistent and uniform coating . [log in to unmask] ______________________________ Reply Separator _________________________________ Subject: [TN] Liquid Photo Imagible Solder Mask and Vias Author: "TechNet Mail Forum." <[log in to unmask]>, [log in to unmask] at CCGATE