Hi Sharon Can be a bunch of stuff. first and foremost, it definitely indicates a bad or iffy board. Insulation = insulation faults / current leakage between nets I have seen: voids or faults in the laminate which could be filled with process fluids conductive fibers in the prepreg or cores, that was weird !!! simple spacing violations from a PTH to a core or signal good idea to investigate what the actual cause is, may lead you to discover stuff you definitely want to know. A good indicator is the actual resistance level at which the leakage fault occurs and if you get consistent readings.. what insulation level are you testing at ? 10 Meg ? / 50 Meg ? / 100 Meg Insulation faults are usually bad news which you want to investigate. Wolfgang > -----Original Message----- > From: Sharon [SMTP:[log in to unmask]] > Sent: Thursday, April 06, 2000 7:19 AM > To: [log in to unmask] > Subject: [TN] insulation problem > > We had few boards that at the electrical test show : "Insulation". > > Does anybody know what can be the reason for that ? > > P.S .