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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