Homebrew PCBs

DaveC <davec2468@...> writes:
> I'm confused: you use LESS hcl and the reaction was faster? I thought 
> the acid is what increased (using more) or decreased (using less) the 
> speed of the reaction, no?

Reactions run fastest when all the parts needed are present in
sufficient quantities.  Pure HCl will *not* etch copper!  You also need
an oxidant!  (amusingly enough, pure HCL *will* take the tarnish off
copper, as the tarnish is pre-oxidized copper) The H2O2 provides an
oxidant, so you need enough of that also.  In a CuCl etchant, the CuCl
is itself an oxidizer and acid, but you still need HCl to provide
additional Cl atoms for it to work.