On Tue, 2009-06-09 at 20:43 +0000, Ken Stuempges wrote:
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> Howdy all
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> Is there much difference between these two as far as etching goes - -
> Time, Temperature, etc? Both are listed for use in etching PC boards.
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I am far from being the most knowledge person here to answer you, and
never used either of those etchants . But if my answer helps...
About difference, the ammonium persulfate SHOULD be faster than sodium
persulfate. But is harder to get. I have also found potassium persulfate
as oxygen adder to swimming pools, it should also etch copper (slowly)
but never tried and no one ever report such thing.
Basically persulfates in water seems to decay in sulfate and oxygen
compound that will etch your copper, so mixing an acid and hydrogen
peroxide will get you at the same point, but cheaper and easier to get.
If you mix sulfuric acid with hydrogen peroxide it etches copper, using
hydrochloric acid will be faster. The sulfuric based is easier to make a
correct disposal, but hydrochloric can be easily regenerated.
Most people will say, use cupric chloride instead. Is the best etchant
you can get. You start with hydrochloric acid and hydrogen peroxide and
make a few boards until it get a green color. And next time bubble some
air there and it will be ready to use again. In the long term it will
get dark, hazardous to use and not etch at all, you will need to add a
tiny bit of it with more hydrochloric acid, and give the remaining to
your friends or arranje a correct disposal for it (suggestions welcome).
See the best reference in the matter
http://members.optusnet.com.au/~eseychell/PCB/etching_CuCl/or just google for cupric chloride etch
> I found Sodium Persulfate to be half the price of Ammonium Persulfate
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> Ken
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