Homebrew PCBs

> John Popelish wrote:
> <snip>
> If you float the board, copper side
> down on the surface of ferric chloride
> etchant, the etching process proceeds
> almost straight up.  The loaded
> etchant is more dense than fresh, so a
> convection cell forms that provides
> fresh etchant to the center of the
> slot (or hole) between two edges of
> resist, and the loaded etchant slides
> down along both sides, preventing
> undercutting, till the copper is
> etches all the way through.  I have
> used this technique to etch holes with
> a diameter equal to the copper
> thickness, and slots narrower than the
> copper thickness.  The sides of the
> remaining copper traces are smooth and 
> almost perpendicular to the board
> surface.
> <snip>

I will give this a try with some CuCl on
the weekend and see if it works with that
and what I think of it.