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1995

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Subject:
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Date:
Fri, 6 Oct 95 16:05:01 CDT
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Background:

We had a PWA fail in the field after approximately 6-7 months.  The unit
was powered on approximately 1000-2000 hours.  Analysis of the PWA
revealed a short had developed between two parallel traces underneath an
IC.  The traces are .006" wide and .010" apart.  The short was not visible
(even under a microscope).  The short was approximately 2 1/2 ohms in
value.  Once a razor was run between the traces the short was eliminated
and the PWA was functional once again.

Someone I spoke to at a PWB Fabricator suggested it might have been
dendritic growth.

Questions:

What is dendritic growth?  
Does causes it on a PWA?
Where can I get more information about it?
Can it be attributed to the PWB fabrication?


Any and all assistance is GREATLY APPRECIATED!


Best Regards,

Mark Lettang
3M
[log in to unmask]
(507)359-0418



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