I agree not enough info. You've asked a question that raises many more questions. However, shooting from the hip and dark memories from far in the past... If woven glass polymide then think polymide = brittle. So how about drill quality? That is to say, what about leakage currents due to crazing and moisture/chemical intrusion into dielectric along he damaged glass/resin interface? CAF? cheers, Dwight Mattix At 02:03 PM 3/23/2004 +0000, Graham Naisbitt wrote: >David > >This is another really misleading statement: > > > > BTW Omega meters are NOT to be used to determine if you have ionic > > contamination. > > Only to used used to detect variations in conductivity from one > > "batch/production run" to another. > > >These instruments were intended to detect ionic contaminants on the surfaces >under test. You measure the resistivity or conductivity of the test solution >(IPA/Water) before testing and again after testing - any change to the >resistivity or conductivity is what in your opinion? > >What is true, is that these machines were only ever intended to be used as a >process control method. Ask Dr Jack Brouse. >-- >Regards Graham Naisbitt > >[log in to unmask] > >Cell: 079 6858 2121 >Office: +44 (0)1252 813706 > >Concoat Limited - Engineering Reliability in Electronics > >NEW Additional Web address: www.conformalcoating.com > >www.concoat.co.uk www.concoatsystems.com > > > > > > > > > Polyimide is well known as a moisture absorbent. I suspect this will be > > a factor in your problem. > > > > David A. Douthit > > Manager > > LoCan LLC > > > > > > > > Russell Burdick wrote: > > > >> Here's a question for all you electrical fans...( ha, ha, ha, not > >> those type > >> of shorts) > >> > >> We are getting high resistance shorting on multilayer polyimide only > >> boards. > >> Inner layers test out with no problem. Immediately after outer layer etch > >> there are the shorts. Omega meter testing shows no ionic contamination at > >> this stage. Baking prior to ET reduces the number of shorts, although > >> after > >> a few days the shorts are back. Construction of board is foil copper at > >> lamination, not cap-core. > >> > >> As usual, any and all help is greatly appreciated. > >> > >> Russ > >> > >> _________________________________________________________________ > >> Free up your inbox with MSN Hotmail Extra Storage. 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