Homebrew PCBs

(below)

--- Robert Hedan <robert.hedan@...> wrote:

> Ok,
> 
> I finally got around to reading the thread about
> muriatic acid and wondered
> if I could do something with the spent FeCl I have
> been accumulating.  I was
> planning on bringing it to the annual domestic waste
> collection done by the
> city, but I'd prefer to recycle it if at all
> possible.
> 
> 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
> :)

If you add muriatic (hydrochloric) acid and oxygenate
it converts to copper chloride. Looking at the
reactions described in

http://artmondo.net/printworks/articles/ferric.htm,
http://www.p-m-services.co.uk/ferric_chloride.htm and
http://members.optusnet.com.au/~eseychell/PCB/etching_CuCl/index.html

you'll find that with excess acid the iron turns into
insoluble ferric hydroxide (rust) and falls out as
sludge. What's left is the regeneratable CuCl2.

I did this myself for my etch tank so I know it works.
In the beginning it seems quite messy due to the rust
depositing on the walls and bottom of the tank but
careful decanting and a good scrub takes care of it.

- YD.


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