Catherine,
Does this happen with inner layers, finished multilayers or double-sided
boards?
It may be due to pin holes in the copper foil but that hasn't been a problem
with European/Usa made foil for a long time.
One way to determine whether it's a foil or process problem would be to put
some panels through a desmear process before etching, if they etch clean
then there are residues on the copper.
It's also possible to check for contaminants on copper after cleaning by
doing a cleanliness test using silver nitrate (I think), clean copper will
oxidise but if there are any contaminants such as resin spots they will show
up bright.

If you contact me off Technet we can discuss further

Geoff Layhe
Lamar Group

-----Original Message-----
From: Catherine Smith [mailto:[log in to unmask]]
Sent: Tuesday, January 27, 2004 6:15 PM
To: [log in to unmask]
Subject: [TN] Low level shiny copper spots after cupric chloride etching


Hello, can anybody help me please?  We are getting low level (up to 5
microns high) copper spots left on inner layer panels after the cupric
chloride etch.  It happens on most kinds of laminate.  We have put panels
through our chemical clean line and the etch only and the effect is still
there.  Leaving out the chemical clean line or pumicing the panels first
still leaves the spots.  The surface is shiny copper and sometimes there
appears to be some residue which we believe to be organic from a slight
carbon peak on an EDAX scan.  We found some sticky residue on the rollers
in the etcher which we removed, but the problem didn't go away.  We run at
4N HCl and 520mV, regenerating with hydrogen peroxide.
Has anyone experienced this before?  Did you discover where the organic
residue came from and the best way to remove it?

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