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May 2008

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Subject:
From:
Victor Hernandez <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
Date:
Tue, 20 May 2008 10:43:08 -0500
Content-Type:
text/plain
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text/plain (149 lines)
Keith,

   Can you share any information on CAF.

Victor,

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Barbara Burcham
Sent: Tuesday, May 20, 2008 10:16 AM
To: [log in to unmask]
Subject: Re: [TN] Blue Voids

Interesting, very very interesting.

I received a technical presentation from Keith Larson at DDi this week
and when I saw this post and looked at the photos, I recalled a photo
that I had seen in the DDi paper by Gil White of a cross section of a
plated hole. 
It was in the section about Conductive Anodic Filament Growth (CAF), and
I quote, 

"Conditions that contribute CAF: 
De-lamination of the glass polymer interface resulting from: 
	Excessive temperature (I.e. 260deg.C for standard FR-4)
	Thermal cycling
CAF is accelerated by:
	Moisture
	Applied potential (higner potential accelerates the process)

Their photo shows the same smeared appearance across the hole and says
the smears are copper migration along glass fibers. 

I have copied Keith into this email so that he can respond. I think they
may have the answer to this thread.
Or, contact Keith at this email address to get the paper or reach Gil
White.
[log in to unmask]

Regards,
Barbara Burcham

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack Olson
Sent: Tuesday, May 20, 2008 9:36 AM
To: [log in to unmask]
Subject: Re: [TN] Blue Voids

Well, since our supplier hadn't seen this condition in their
microsections,
and the independent lab used different equipment (Scanning Electron
Microscope
and Differential Interference Contrast photography), the question became
whether
the supplier's lab could even see the condition if it was present.

The independent lab still has the sample panel with the known condition,
and
they
agreed to send back half of the panel so the supplier can experiment
with
it.
In the meantime, our company issued a corrective action request so we
get
some
kind of follow-up on the results.

Thanks to everyone who looked at the evidence and sent their opinion.
http://frontdoor.biz/PCBportal/bluevoid.jpg

p.s. I think its kind of fun to do this (especially when it is not MY
company's sample)
Maybe we should have more community "case studies", I find the group
feedback to be very educational, especially when the descriptions in
IPC-A-600
are vague.

Thanks again.
onward thru the fog,
Jack

-----Original Message-----

What became of this issue?   I have not seen any more threads of e-mail.

Victor,

From: TechNet [mailto:[log in to unmask]] On Behalf Of [log in to unmask]
Sent: Tuesday, April 29, 2008 9:59 PM
To: [log in to unmask]
Subject: Re: [TN] Blue Voids

Are the voids in the glass bundle or between the glass bundle and the
resin?
If the former, you have a glass supplier problem (not all the weaving
assistant burned off?)-- if the latter, then I would suspect incorrect
pH in the
adhesion promoter application bath.


Bill  Kenyon
Global Centre Consulting
3336 Birmingham Drive
Fort Collins, CO  80526
Tel: 970.207.9586   Cell:  970.980.6373

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