Homebrew PCBs

Just like what drives pretty much everything in this universe, entropy. 
The copper ions in solution are more electronegative than aluminum 
metal. As a result electrons are transfered from aluminum to the copper 
ions. The copper atoms become neutral (metal) and the aluminum atoms 
become ions (dissolved in solution).

Why is your experiment be a failure?. You clearly determined the answer 
to your question if ferric chloride can turn an aluminum surface black.

lcdpublishing wrote:
> Hi guys,
> 
> Perhaps one of you chemistry guys knows what happened here.  While 
> etching a board, I got to thinking about how the Ferric Chloride 
> stains some metals (and wood, and other things) black.  Always one to 
> try things, I dipped an aluminum bar in the stuff for a few seconds.
> 
> When I pulled it out, it had what appears to be rust scale on it like 
> crazy!  I assume this to be bits of Copper and not rust, but I was 
> wondering if someone could explain what happened there?  I don't think 
> it was electrolysis - no electricty going through the mess.
> 
> Yet, somehow, the copper seemed to attract to the aluminum - it didn't 
> stick though.  A rinse in water removed it quickly.  The aluminum did 
> turn gray in color and not black like i had hoped - so it was a failed 
> experiment.  But, it sure was interesting and raised a few questions!
> 
> Chris
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