FSL (Finishing Services Limited) out of Texas has a system for recycling both
ammoniacal and cupric.  I have some limited familiarity with both, as
customers of ours have used both, and both require a little bit better
housekeeping than using simple feed and bleed replenish.

The Cupric replenisher seems, (and this may have been user circumstance)
particularly prone to picking up resist residues, and clogging.

The ammoniacal system requires real close attention to amount of air being
drawn in, because the cuprous ion tends to build, and this slows etching.
Perhaps this really requires putting an anhydrous ammonia pH control on the
system, which then allows an excess of air to be put through the system.   An
excess of air will keep the Cuprous ion down, but also will cause the system
to lose too much ammonia, thus depressing pH.

The fax number for FSL in the US is 972-790-5376

Rudy Sedlak
RD Chemical Company

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