Kevin,
Have you tried to x-ray the area? It might help sort out the copper vs.
residue / discoloration issue.
Bruce Tostevin
Benchmark Electronics
Hudson, NH
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Kevin Glidden
Sent: Friday, September 28, 2007 10:51 AM
To: [log in to unmask]
Subject: Re: [TN] Copper Staining in PCB laminate
Thanks Ian,
Would you expect black mask to leave a copper colored residue?
If you look closely at the picture, you can see the inner layer copper
clearance from the NPH, and then the "residue" appears to be the same
exact
coloration.
Kevin Glidden
Manufacturing Engineer
Luminescent Systems Inc.
-----Original Message-----
From: Ian Hanna [mailto:[log in to unmask]]
Sent: Friday, September 28, 2007 10:50 AM
To: TechNet E-Mail Forum; Kevin Glidden
Subject: RE: [TN] Copper Staining in PCB laminate
Hello Kevin
Lets re-define 'inside'. If its mask pigment It could easily be
trapped
in the pours of the laminate on the outside surface and not easily
cleaned
off. Does it appear to be on (or very close to) the outer surface, or
does
it appear deeper in the material? I find depth-of-field on a microscope
a
useful aid in establishing relative depth of features...
If it's only a discolouration on (or close to) the surface of the
laminate I
would use the boards and lightly grill the supplier. If it appears on
the
copper or silkscreens or seems deeper inside I would demand a much more
comprehensive analysis prior to use.
Again, my first suspect would be the black soldermask -- this stuff
can be
brutal to fabricators (and I'm a fabricator that uses black mask with
regularity)
Ian
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Kevin Glidden
Sent: Friday, September 28, 2007 10:19 AM
To: [log in to unmask]
Subject: Re: [TN] Copper Staining in PCB laminate
It appears to be inside - it doesn't clean off.
Kevin Glidden
Manufacturing Engineer
Luminescent Systems Inc.
4 Lucent Drive
Lebanon, NH 03766
(603) 643-7766 x3152
-----Original Message-----
From: Ian Hanna [mailto:[log in to unmask]]
Sent: Friday, September 28, 2007 10:07 AM
To: TechNet E-Mail Forum; Kevin Glidden
Subject: RE: [TN] Copper Staining in PCB laminate
IS this staining on the surface of the laminate or does it appear to be
inside. Is there any indication of residue on the copper surface. My
first
guess would be pigment from the black solder-mask, but that's just a
first
guess...Ian
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Kevin Glidden
Sent: Friday, September 28, 2007 9:06 AM
To: [log in to unmask]
Subject: [TN] Copper Staining in PCB laminate
We recently received a shipment of PCBs where the exposed outer layer
laminate has staining that looks like copper. I have a photo -
<http://tinyurl.com/yp9za2> http://tinyurl.com/yp9za2 My question is
what
would cause this? I've never seen it before, but I am thinking
something in
the Copper plating process. The vendor is telling us it is staining but
it
is an asthetic issue only. What would cause it?
Is it
an asthetic issue only? It seems to me if the staining was caused by
some
plating chemistry, then it would effect the laminate properties,
particularly the insulation resistance.
Thanks!
Kevin Glidden
Manufacturing Engineer
Luminescent Systems Inc.
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