Homebrew PCBs

"Bob Macklin" <rottenrobbie0@...> writes:
> Is the etching mask created from a laser printer conductive? Could
> the same process be used to create a solder mask.

Toner's plastic and, I think, carbon.  I tested a sample and no, it
doesn't seem to conduct.  However, it's also not heat resistant.  See:

http://www.delorie.com/electronics/alarmclock/20070705-power.html

At the center pin of U400 (lower left, the 7805), you can see the
solder went right over the toner line.  Granted, there's a lot of
solder there... quick test, as I still have that board... nope, I
tried soldering a trace that had toner on it, and the solder went
right through it as if it weren't there.

Interesting enough, the toner did survive the hotplate reflow.  I
suspect that's just because nothing was there to physically move it,
so it just re-solidified in place.