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 .