Homebrew PCBs

johnwhitneyfiat wrote:
> I have been off the group for a while and I'm sure this was covered.  
> In the direction for making etchant from Hydrogen Peroxide and Muratic 
> Acid, it says that you can regenerate with a bubbler.  How long does 
> this take?  I know it will depend on the amount and the area that was 
> etched, but is there a rule of thumb to make it work. I do have to day 
> that I make a small bathch and it worked great on a sample board.
> 


Many factors involved, it could be 15 minutes or 2 days. Obviously the 
more air that contacts the solution the quicker all the Cu(1+) converts 
to Cu(2+). So more air, and smaller bubbles are two factors you can 
control to increase speed. My etching solution seems to foam a little, 
which *dramatically* increases the regeneration speed. Maybe add a drop 
of dishwashing detergent ?
If your doing air regeneration, then make sure fee HCl concentration is 
 > 1 Molar or 5% wt, and specific gravity is above 1.30 , which 
corresponds to about 140 grams/liter of dissolved copper. Having less of 
these two parameters and you compromise etch speed.