Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

You could paint the unused side with clear lacquer or polyurethane, etch
the trace side, then
make an isolation drill bit. Where ever you need a through-hole item,
drill the hole from the trace side, then on the
other lacquered side use the isolation bit to scrape/make a pad on the
other side.

This way the lacquered side can also be a big ground plane and wont need
to be etched away, wasting etchant.

2 ways to make a isolation bit:
1) if you are good with a dremel, use a disc or grinding bit and grind
the tip of a spare drill bit so that the cutting edge is slightly a W
with the center able to go into the tiny hole, and the outer W legs able
to cut the pad. Be careful or it will cut all the way thru.

2) Use a large enough drill bit that can be centered in the hole, but
the V of the cutting edges is wide enough to give about a 1/16" or 1.5mm
wide insulating crater in the the PCB. Turn the drill bit by hand or
carefully in a drill press.
-Lee