Homebrew PCBs

"Kim Vellore" <kimvellore@...> writes:
> Wondering why this would be faster than dipping the board in FeCl

Read the Pulsar site for the full details, but basically, the key is
that the "spent" FeCl is quickly replaced by "fresh" FeCl at the
copper surface.  You get similar results with spray etching, for the
same reason.

When FeCl hits copper, it quickly reacts - but leaves the spent FeCl
there, blocking further reaction.  The faster you can get the spent
FeCl away from the copper, the faster the etch goes.