I suspect it is a small short. Is CAF possible in polyimide flex? I
thought it only occured in stranded materials such as FR-4 and its
variants. Can anyone clarify this?
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Wayne Thayer
Sent: Tuesday, May 08, 2007 12:04 PM
To: [log in to unmask]
Subject: Re: [TN] Strange one?
I think maybe you removed the smoking gun, as Chuck is indicating, by
having too much current during test. If you have more of these types of
defects you should be able to detect their presence at much lower
currents so that hopefully you can see the nasty little bugger which was
responsible. I presume the boards were continuity tested post
manufacture, and the shorts developed later. What was done to the
boards in the interim. Biased humidity perhaps? If that's the case,
could be CAF.
Wayne Thayer
>>> [log in to unmask] 5/8/2007 12:53:38 pm >>>
Iian,
Stop fixing small shorts with your hi pot tester. Wow, Big flash and
the short is gone leaving you on pic 1 a delaminated area and on pic 2
the
burnt remains.
Bet if you look real close you will find a sliver of metal or a copper
fiber.
Chuck Brummer
3M Manufacturing Engineer
8357 Canoga Ave.
Canoga Park, CA 91304-2605
(818) 734-4930
"Braddock, Iain" <[log in to unmask]> Sent by: TechNet
<[log in to unmask]>
05/08/2007 09:23 AM
Please respond to
TechNet E-Mail Forum <[log in to unmask]>; Please respond to "Braddock,
Iain" <[log in to unmask]>
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Subject
[TN] Strange one?
Hi all,
Stevie G has been kind enough to post a couple of pics of a flexi
anomaly I've come across.
Been having problems with some flexi-rigid boards failing at Ins/Cons
test due to insulation breakdown - tested at 200v.
Had the lab do some exploratory work and the guys have come up with
these pics. along with the fact that the Polyimide was conductive
around the areas highlighted on the pics. but only localised. The Lab
view seems to be that something was left on the board during
fabrication
and caused the problem; they have their suspicions but would like to
know if anyone else has encountered a similar problem.
http://stevezeva.homestead.com/files/Flex_Problem_1.JPG
<http://stevezeva.homestead.com/files/Flex_Problem_1.JPG>
http://stevezeva.homestead.com/files/Flex_Problem_2.JPG
<http://stevezeva.homestead.com/files/Flex_Problem_2.JPG>
Regards,
Iain.
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