Great answer Mr. Stern.

May I add that what is done with the spent etchant can also dramatically
effect cost of stripping.

With Ammoniacal, the spent is always returned, usually at the cost to the
generator, to the supplier of etchant.   Cupric, regenerated with either
Chorine, or Hydrogen Peroxide has the POSSIBILITY of becoming a commercial
source of Cupric Chloride, (at least of spent etchant from the PCB industry),
and thus can become a source of revenue.

I qualify this heavily, as the EPA has trouble dealing with treating
(hazarous) wastes as raw materials for other processes.

Rudy Sedlak
RD Chemical Company

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