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
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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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