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April 2008

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Subject:
From:
Paul Reid <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Paul Reid <[log in to unmask]>
Date:
Tue, 29 Apr 2008 15:38:12 -0400
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text/plain
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text/plain (86 lines)
Hi Jack,

I believe that the condition I am seeing is crazing. Crazing is a
separation between glass fibers and epoxy. It is a site for conductive
anodic filament (CAF) growth. I have seen boards with this condition
fail due to shorting. This may not pass "HiPot" testing. 

We see crazing frequently in lead free applications. If the crazing
violates your minimum spacing requirements I believe it is rejectable. I
would bring this condition to a material review board (MRB) for
disposition.

Sincerely,

Paul Reid

Program Coordinator

PWB Interconnect Solutions Inc.
235 Stafford Rd., West, Unit 103
Nepean, Ontario
Canada, K2H 9C1

613 596 4244 ext. 229
Skype paul_reid_pwb
[log in to unmask] <mailto:[log in to unmask]>


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack Olson
Sent: Monday, April 28, 2008 11:03 PM
To: [log in to unmask]
Subject: [TN] Blue Voids

Greetings!

Once again I am caught in the middle of a bare board problem, (never the
same thing twice!) Maybe after a few more decades of failure I might
become more proficient at evaluation, but in the meantime....
Does anyone have a quick reaction to this picture?

http://frontdoor.biz/PCBportal/bluevoid.jpg

I'm told there are voids in the glass fiber bundles.
When I reported it to the manufacturer, they asked that blue dye be
applied to see the penetration. It all looks blue!
(and other areas look "bluer" than the problem area to me) The
description in IPC-A-600 is too brief to comprehend and I can't find
anything in Printed Circuits Handbook about it.
anyway,
I'm not doubting anything I've been told by "the experts", my question
is:

How would you handle this if you saw it in YOUR report?

reject?
use the boards but ask for corrective action?
process indicator but not really a problem?
not sure, but monitor with more xsec?

onward thru the fog,
Jack

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