It would seem that vent regulation could be used to control pH; however,
what then happens to the fine control of chlorides?  The reason this is
asked is vendor etchant contains varied amounts of ammonia gas (i.e.,
control of one means loss to the other?).

How about ammonia gas controllers and oxygen input devices with fixed vents
for chloride regulation?  Where are these purchased?

Thanks,
Paul Wilson

-----Original Message-----
From:   Sarah Boutwell [SMTP:[log in to unmask]]
Sent:   Thursday, August 26, 1999 11:44 AM
To:     [log in to unmask]
Subject:        [TN] etching pH controllers

Hello everybody
I would like to add a pH control system to my ammoniacal copper etcher that
would open and close a vent based on the pH of the bath.  Does anyone know
of a company that supply me with something like that?
Thanks


Sarah Boutwell
Manufacturing Engineer
Johnson Matthey Advanced Circuits
[log in to unmask]
612-684-5079

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