Homebrew PCBs

I used AP for years it worked out great for me.  The solution doesn't keep too long so I would just make up what I needed for that job. Heating is the key, it doesn't work unless it's hot.  Also, a few ppm of HgCl2 really increases the etching speed but that adds a toxic element to the mix, but doesn't take much at all.  These days, Hg is one of those bad actor metals, though I must admit to haveing quite a few milligrams in my teeth and played with a few Hg covered pennies.  Unless you have a proper and legal spent etchant disposal process it's use is not advised.

Craig 

--- In Homebrew_PCBs@yahoogroups.com, Tom Biery <judsquare@...> wrote:
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> Can someone please tell me why not just use Amonium Persulfate.  It seems freely available, that is what I am using and it works fine, I find that if maintained at a temperature of 120 degF the etching is complete in 20 minutes.  What am I missing?
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