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April 2008

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Subject:
From:
Gabriela Bogdan <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Gabriela Bogdan <[log in to unmask]>
Date:
Tue, 29 Apr 2008 20:34:22 +0300
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Forget the dye and check for the paper
Measles in Printed Wiring Boards in
http://www.ipc.org/ContentPage.aspx?Pageid=4.1.0.5.
You can download the paper free.
It is one of the first papers on base material defects in printed circuits.
In my opinion you are dealing with CRAZING of the glass fibers and the 
requirements are not so clearly stated in IPC-STD-600 and IPC-STD-610.
You are right that the matter is "foggy".
Usually it is not considered a major failure, but you decide according to 
your application, or you may perform some environmental tests.
Under humidity, temperature and current copper may migrate along the glass 
fibers and cause shorts in dense circuits.
www.smta.org/files/SMTA_Boston_pbfree_ddi.pdf
Maybe you have also "hollow fibres"?
I saw this article and found it interesting
www.dfrsolutions.com/Assets/2001_HollowFibers_Hillman.Rogers.pdf
Gaby
----- Original Message ----- 
From: "Jack Olson" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, April 29, 2008 6:03 AM
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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