Hi Victor,
Pattern plating does have a profound affect on crazing. Crazing is
formed first by poor drilling. The pattern plating does permeate down
the crazing producing a condition called wicking at the defect sight
next to the drilled hole. The plating solution continues deep in the
crazed glass bundles. Wicking is generally considered to end where the
copper plating ends but if you read the definition of wicking it is the
moisture penetration down the glass fibers and is not limited to where
the copper plating has occurred. The capillary action formed by the
crazing is enough to have the plating bath wick into the spaces between
the epoxy and the glass fiber. The copper plating seals the end of the
wicking trapping plating solution in the space formed by the separation
between the epoxy and the glass fibers.
The contaminant is trapped in the space between the glass fibers and the
epoxy waiting to grow into CAF.
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
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________________________________
From: [log in to unmask] [mailto:[log in to unmask]]
Sent: December 16, 2013 8:06 AM
To: Paul Reid
Cc: [log in to unmask]
Subject: RE: [TN] Crazing - the pictures
How does pattern plating effect crazing? Many oversea shops pattern
plate.
Victor,
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Paul Reid
Sent: Friday, December 13, 2013 3:09 PM
To: [log in to unmask]
Subject: Re: [TN] Crazing - the pictures
Hi Wayne,
There are a number of things that bring these boards into question. What
I am concerned with is the crazing.
I think that the fabricator has an automated plating line that requires
two passes to get the copper thickness.
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]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Wayne Thayer
Sent: December 13, 2013 1:13 PM
To: [log in to unmask]
Subject: Re: [TN] Crazing - the pictures
Hi Paul-
Nice sections.
Aren't they supposed to have the drill actually spin when they push it
through the board?
What's going on with the two layers of plating? That first layer is
more than electroless would normally put down. I guess maybe they
checked hole size reduction to see how much plating they put down,
realized they'd missed a minimum on the hole wall, and put it back into
the bath.
I tend to think of the defect you have been talking about as "heavily
damaged fibers", and think of crazing as voids/cracks within the
prepreg. I agree that I would be very concerned about the long term
reliability of these boards and would like to know how much fallout the
fabricator had due to plating shorts along these damaged fibers.
Wayne
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Paul Reid
Sent: Friday, December 13, 2013 12:49 PM
To: [log in to unmask]
Subject: [TN] Crazing - the pictures
Hi Everyone,
I finally found Steve Gregory's email address. He has kindly posted some
the pictures of the crazing that I found.
http://stevezeva.homestead.com/6494_2_1_mod.jpg
http://stevezeva.homestead.com/6494_M_001.jpg
http://stevezeva.homestead.com/6496_2_10.jpg
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]
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