Homebrew PCBs

On 22/03/2012 16:30, Dave wrote:
> A number of years ago, I had done some rough calculations and a
> bit of empirical testing (which turned out mostly unsatisfactorily),
> involving electrolytically regenerating spent Ferric Chloride
> solution. My approach involved electrolytically depositing the
> Copper out of the solution, and replacing it with Iron. The
> electrolytic deposition of the Copper did work (I ended up with
> some beautiful looking "Copper trees".), and the Iron anode
> did dissolve. There was little (if any) Chlorine gas evolved.
> But, I'm not real sure that the Iron that was dissolved formed
> Ferric Chloride, or some other allotrope (e.g., Ferrous Chloride,
> etc.). However, it may be worthy of further study.
>
> Note that one of the problems with etching Copper with Ferric
> Chloride solution is that the result is a Copper Chloride, as well
> as a Ferric Hydroxide (that brown, muddy looking stuff). The
> Ferric Hydroxide has to be removed from the active area of etching,
> or it'll clog up the etching process.

Cupric chloride is a good etchant, so you didn't need to remove the 
copper! You just needed to add some HCl and bubble air through it, or 
use some H2O2 to oxidise the mixture.

Leon
-- 
Leon Heller
G1HSM