Homebrew PCBs

On Thu, 12 Oct 2006 00:07:24 +0200, Philip Pemberton  
<ygroups@...> wrote:

>
> Lye? As in sodium hydroxide, the stuff you use to develop PCB  
> photoresist?
> Might work, but the real attraction of carbonate is that it's pretty much
> harmless (it's used as a food additive, and sodium bicarbonate, aka
> bicarbonate of soda, is a derivative of carbonate) and produces less  
> froth,
> foam and CO2 than bicarbonate of soda. Plus carbonate is cheaper and  
> better
> for dealing with FeCl spills - it's a powder so it'll soak up FeCl and
> neutralise it at the same time.
> IIRC, the trick is to add the carbonate until the solution is slightly
> alkaline, then pour the resulting mess through a coffee filter to catch  
> the
> sludge. Pour the liquid away (it's just water and sodium salts IIRC), and
> dispose of the filter 'in accordance with local laws' so to speak - that  
> ends
> up being covered in fairly pure iron and copper. If you wanted, you could
> (theoretically) split that apart and make up a solid copper/iron lump  
> over
> time, then sell it to a scrap dealer once you've got enough (note how  
> high
> copper prices are these days).


Ok, what about lime (from the builders yard)?

ST