[sdiy] Two more questions

Robert Kent hanuman at ccsi.com
Wed Aug 7 08:10:24 CEST 2002

On Tue, 6 Aug 2002, Steve Begin wrote:
> I made a circuit a long time ago from an old magazine, I used a
> permanent marker on copper and then etched it, but I don't have
> a steady hand and it was sloppy, some parts were thin, some were
> thick, etc.  The etching where you use light sensitive chemicals
> seems to be way too much work but maybe it's easier than it sounds.
> I've also seen rub-on decals which I'm guessing are used instead
> of a marker.

  I feel the dry transfers, which you can find at Radio Shack
(part #276-1490) yield the best results attainable by the hobbyist,
period. I've never seen a photo-etched board produced by an individual
that comes close. And unlike any other method I can think of, little
to no skill or practice is required for a high-quality board. (For
the resist stage, anyway.)

  I must temper my bold words with the admission of why most people
don't use or even mention this product: laying down the transfers
is a tedious, time-consuming process which must be duplicated in
its entirety for multiples of the same board. (Unless you scan or
photocopy the board when you're done to make a photomask. ^_^)
Registration for double-sided boards is pretty much impossible.
Board layout should be finalized on paper before you start.

  Anyway, for smaller boards with a few ICs like guitar effects
and such, I prefer to use the decals and touch up with a resist
pen as a reasonably fast way to just get the board done.

  Note that Radio Shack's resist pen appears to be an un-branded
Sharpie marker. They smell the same, anyway. (...)

> Vero board looks like it could get sloppy in inexperienced hands.

  I find that PCBs are much more reliable, since it's such a pain
to re-work screwups that I'm motivated to triple-check schematic
against layout every step of the way. ^_^

  A note to address the topic of cutting PCB material: it's my
understanding that the dust created by machining glass epoxy PCBs
can cause lung damage similar to Asbestosis. I would recommend
any cutting or drilling be done outside, using some sort of
respiratory protection. The preferred method of cutting PCB stock
is of course a board shear. I'm sure a guillotine paper cutter
with a sharp blade would work pretty well. I personally use a
cheap nibbling tool (Radio Shack part #64-823), but this is
time-consuming and destroys a 1/4" strip of material.

  Best of luck!

--Robert Kent
  hanuman at ccsi.com

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