At 06:09 PM 2/7/97 -0500, you wrote:
>Has anyone done a historical study on TOC uses for copper plating baths?
>
>Does one obtain useful information about contaminant buildup, or is
>liquid chromatography the way to go?
>
>Thank you.
>
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Over time I think we have tried every method for controlling our copper
baths. Our supplier (Mac Dermid) recommends TOC as a method for quantifying
contaminate levels in copper plating. We have found it to be helpful in
determining when to carbon treat. I believe Pete Dzioba of MacDermid has
done this study.

A few years back I was convinced that HPLC was the way to monitor and
control copper plating. Unfortunately, we were never able to get consistent
readings on a bath more than a few weeks old. As I recall, there were three
distinct peaks on the HPLC graphs. A large copper sulfate peak, a peak of
fresh (unactivated) brightner and a peak for active and spent brightner.
Once the bath was more than a few weeks old, the base of the peaks widened
and we were not able to successfully seperate and quantify them. It has
proven to be a very useful tool during carbon treat though. You can tell
when the bath is clean because you only have one peak. Also, after you have
transferred the bath to the plating tank and are dummy plating you can tell
when the brightner is activated because the fresh peak shrinks, and the
active peak grows. I don't fully understand this but we found there was a 5
or 6 hour lag time for brightner to become active. When we started up baths
with just hull cells, we usually ended up with too much brightner after a
fews days. The HPLC at least verified that and gave us a visual indicator of
when it was active.
  This is probably more info than you wanted, but we have found that no
single control method is sufficient. We use CVS for plating efficiency and
wetter quantity, TOC as a measure of contaminants, HPLC for monitoring the
quality of carbon treat and bath start-up, and of course there is no
substitute for the old stand-bys, hull cell analysis and tensile and
elongations. 

Regards,
David Arivett
>
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