Etching with Ammonium persulphate

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Joined: 31/12/2012
Location: New Zealand
Posts: 8850
Posted: 07:38am 31 Dec 2021      

Just use the 1:5 ratio.
Ignore the copper cm-squared.
Just have enough volume to cover the PCB as mentioned by phil99 above.

Ammonium Persulphate solution MUST be heated to work.
If you try to use it at less then about 70'C, it will not etch at all.
You will need some kind of heating bath.
70'C to about 90'C works well, anything hotter then that will cause extreme excitation of the fluid, and will probably etch away the pattern you want.
A digital thermometer is your friend here, as you can then keep track of the temperature of the water bath.

I used an old hotplate, with an old frypan 3/4 filled with water, and boil that up.
Put your etch bath into the hot water, and agitate/monitor.
It will NOT etch if not heated, but I said that before.

Used it LOTS of times for home-brew PCB's, and always worked fine.
MUCH cleaner and less staining then Ferric Chloride.
But now I get ALL my PCB's from PCB houses, so I don't really bother with etching at home anymore.