Homebrew PCBs

--- In Homebrew_PCBs@yahoogroups.com, Robert Hedan <robert.hedan@...> 
wrote:
>
> Ok,
> 
> 
> So I googled and found this link:
> http://www.qsl.net/iz7ath/web/02_brew/14_howto/02_clor/index.htm
> 
> This guy regenerates ferric chloride, but that contradicts this link 
> from
> the muriatic acid thread:
> http://www.smallsolar.org/workshop/etchant/index.htm
> 
> - Copper Chloride has one important benefit that the other commonly 
> used
> etchant chemicals (Ferric Chloride and Ammonium Persulphate) don't 
> have:
> when it "wears out" it can be regenerated.
> 
> So, before I nuke my back yard, can I regenerate ferric chloride?  
> And if
> so, what would be a 'relatively' safe procedure?
> 
> Robert
> :)
>

I regenerated Ferric Chloride with just muriatic acid at first. The 
result didn't etch as fast as new etchant, but worked. Eventually, 
however, I found that beauty supply strength H2O2 (40 Volume = 12% 
strength) would regenerate it far better. You can find it at Sally 
Beauty Supply if you are in the US, you may have difficulty finding 
anything over 20 volume elsewhere, try hairdresser and beauty supply 
shops that have hair products. I use about 32 oz per 2 gallons of 
etchant, so divide that up to find out how much to use. You should 
still add a little acid to keep the pH low. Maybe about a half a cup 
to a cup. I don't measure in much detail.

Using the H2O2 will produce a LOT of foam and some heat, so make sure 
the etchant is in a sturdy container (I use a 5 gal bucket inside 
another 5 gal bucket) and don't add it too fast or it will 'boil 
over'. The resulting etchant works faster than fresh etchant from 
Radio Shack.