Homebrew PCBs

Personally, I've had exceptional results using the sponge method with
Ferric Chloride on both toner transfer (with the TRF layer) and
photo-resist.  In fact I consistently get better results with
photo-resist than w/ toner.  As long as I'm paying attention I get
very little if any undercutting.  Just my 2 cents.

--- In Homebrew_PCBs@yahoogroups.com, "Andrew" <andrewm1973@...> wrote:
>
> 
> > > "Andrew" <andrewm1973@> writes:
> > > I have not yet.  I am scared that the little ~6
> > > thou tracks will get scratched.
> 
> > DJ Delorie wrote:
> > Pulsar does recommend the TRF layer to protect the
> > toner if you're going to use a sponge.  It's a
> > thin film that sticks to the toner to seal it and
> > add some physical protection as well.
> 
> Probably won't help me as I am one of those photo
> zealots.
> 
> I think until I get spray etching happening I will
> just stick to Ferric Chloride on boards with <8 thou
> dimensions.  The CuCl just undercuts more from
> my expereince.
> 
> > Perhaps a test board would be useful?  I've got
> > one here I use for such things:
> >         http://www.delorie.com/pcb/
> > scroll down to "Goodies" and download the bloat
> > test board (pcb, pdf, gerber).  It's got various
> > traces and spacing, plus various annulus sizes,
> > from 12 mils down to 1.
> 
> Thanks - Will have a look at the bloat plugin.
> 
> I only just converted to gEDA/PCB last week and
> am only just getting up to speed on it and learing
> how to draw footprints and symbols at present.
> (And I will probably be one of the people you
> scream at for doing heavy symbols)
> 
> Going to give your teardrop plugin a go as soon as
> I have drawn a real PCB.
> 
> http://www.thehacktory.com/Simple-IR-RX-Prototype-V1p4-Top.jpg
> 
> Is a picture of the final ever board I will
> draw with old protel for DOS.  Down at this 
> size the imperial back end that only went to
> 1000ths made things frustrating.  All the traces
> and clearances should have been 0.2mm but the SW
> randomly made them about 6 or 7thou on print out.
> 
> The three packages shown are
> 
> A SC75-6 package with 0.5mm pitch (easy)
> A Motor driver in a DFN10 with 0.5mm pitch (easy)
> ATMega48 in a QFN28_4_EP that has 0.45mm pitch
> 
> That last 0.05mm makes a difference.
>