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Date: | Tue, 18 Mar 97 08:02:34 cst |
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I agree with the enclosed assessment on crystals in the acid
copper bath and would go as far to suggest pulling anodes
out of the acid copper bath. It is definitely NOT a case of
more is better with anodes. Many brightener systems form
their acting ingredients at the anode and require a specific
anode current density, or a ratio of anode area to cathode
area.
Has the cathode area you're plating gone down recently due
to product mix changes? Is the copper concentration in the
acid copper bath rising?
Also, check to see if your copper anodes are passivating
indicating poor connection or too much anode surface area in
the plating tank. This check is simple. Anodes pulled from
the tank should be black with anode film. If they are
copper colored or gray, connection is poor or there is too
much anode area in the tank.
Hope this helps.
Dave Sullivan
Rockwell Collins, Inc.
[log in to unmask]
______________________________ Reply Separator _________________________________
Subject: Re: Acid copper bath
Author: [log in to unmask] at ccmgw1
Date: 3/17/97 2:26 PM
Is this problem manifested by crystalization of copper on the anodes? On the
bottom of the anodes, right? Is it more prevalent on some parts than on
others? Have you looked at the anode c.d., the cathode c.d. and the
resulting anode-to-cathode ratio? Is it high or low? Have you tried anode
shielding? Have you tried different concentrations of sulfuric acid?, (this
crystalization is the "common ion" effect, sulfate being the ion).
There could be several answers but I've seen anode shielding fix it.
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