--- In
Homebrew_PCBs@yahoogroups.com, DJ Delorie <dj@...> wrote:
>
>
> "fenrir_co" <fenrir@...> writes:
> > since I etch brass sheet and not PCBs
>
> Could you elaborate on this a bit? I'm thinking of etching my own
> solder paste stensils for my next project.
>
I etch through brass sheet (hobby stores carry 4" x 10" sheets) in
.005" and .010" thickness. I've done .016" and .032" but it takes WAY
too long and there's massive amount of undercutting.
Usually I only transfer to one side and spray paint the other side
with oil based (not acrylic/latex) paint from a can (specifically,
Rust Oleun's cheaper 'Painter's Touch'). Red makes a good contrast
against the brass to see how well the etching is going. I suspend the
brass sheet face down in a tray of etchant using a sheet of acrylic
with 'feet' and slide-in runners made of more acrylic superglued onto
it so I don't have to do any taping or such to hold it up. With fresh
etchant the .005" takes about an hour, hour and a half, double the
time then take a little off for the thicker ones. Once it's done I use
a little bit of acetone which makes the paint bubble, let it dry just
a little and you can lift it right off.
Don't spraypaint until 2 days before you plan on etching. Earlier than
that and the paint won't be dry underneath. Longer than a few weeks,
the paint will be difficult to remove.
(deleted/reposted on the group page to correct the brass sheet size.
Forgot the zero)