Years ago at another employer we found "tunnels" in the laminate that contacted adjacent traces (or even skipped a trace). They sometimes filled up with flux or water. Prior to processing, we could not detect the defect. If the panel was baked dry, it no longer shorted. These are real hard to detect, but you can look for them. ______________________________ Reply Separator _________________________________ Subject: [TECHNET] Long Term Failures in Multilayer PCBs Author: "LANE; Stephen (Collroad)" <[log in to unmask]> at INTERNET