Homebrew PCBs

dkesterline wrote:

> 
> I tried this and my results were less than stellar. The negative 
> terminal collected particulate copper (kinda looked like a sponge, 
> but just dust, wiped off easily) and the negative terminal did erode 
> some (about 1 hour). In the end my etchant looked like brown mud. 
> Then I tried etching with it and it seemed slower than before I did 
> it.

If you have potential too high then your change all your ions. 
I.e. you get hydrogen ions (+1 charge) and copper ions (+2 
charge) attracted to the negative terminal because that's where 
electrons are being feed. Simultaneous deposition of hydrogen gas 
and copper metal make you a messy sponge.
Lower the cell potential so hydrogen no longer evolves and you 
get only copper.

On the opposite side your anode will attract negative ions 
(anions) i.e. chloride (-1 charge) and hydroxide (-1 charge).
But you have iron anode material, and electrons are being sucked 
away from the surface. The result is iron becomes iron ions (+3 
or +2 charge). The chloride ions don't get a chance to give up 
their electrons because the iron does it so much easier. The 
hydroxide may do it a little bit and so you might get some oxygen 
gas evolving.

Electrochemistry is a nightmare to understand.

I wouln't expect results, at best you can plate out all the 
copper and finish up with saturated ferrious chloride solution.


Adam