PCB Etchant bath
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To create a good to excelant printed circuit board, it is essential that it be emersed in a heated
etchant solution of either ammonia persulfate or feric cloric acid. Ideally, this container would
be made of glass or molded plastic. If a pump is used to fill and drain the unit, the pump must
not have seals or any metal parts which would be effected by the acidic solutions. Because these
solutions have a ph at or below 7 they are safe to dispose of in small quantities in the normal
household drainage system.
The heater is usually a test-tube style bath heater available at the local electronics supply
house. Use of the heater reduces the risks of the etchant under cutting the circuit traces due
to long exposure to the acid.
Using a small air pump blowing into a tube which is submersed into the solution and is filled
with tiny holes supplies a slight agitating action to assist in the process. Another method is
to use a small ultra-sonic vibrator which is afixed to the bath enclosure.