Just to report:
Someone mentioned the material advertised at:
http://renaelectronics.com/product_stencil.htmfor use making stencils. I bought some and can report that it works
well, much better than I had expected. The price seems a little high,
but not compared to $180 for a steel stencil. At $10 (3 sheets in a
$30/pack) it makes good sense for small-scale users.
I blew the first attempt (my mother claims that I have a congenital
defect inherited from my father that prevents me from following
directions, my wife just says that I am an idiot). I probably mixed
the developer too strong.
But the second try was almost perfect. I made a print on transparency
film of the PDF file they provide of shaft encoders, and four of the
six came out perfect, two were slightly over-bitten (sp?) & lost some
interrupter partitions at the periphery. All cut free of the primary
sheet cleanly.
I have never used FeCl2 on Steel before, & had no idea it could be
chemically machined with such fine detail under simple conditions.
There are a few details that were unclear to me on Rena's website.
This is what I did:
I just sandwiched the printout against the sensitized material with a
(sort of) clean piece of Plexiglas 1/4 inch (6.35 mm) thick and
exposed it at 7 inches (180 cm) from a two bulb 24 inch florescent
'shop-light' fixture with two 20 W bulbs (one a grow light 'broad
spectrum', one a standard kitchen & bath - just what I had) for 10 to
15 minutes.
I am suspicious that 15 min was too long, and 10 was too short.
Systematic (that will be the day) testing would probably perfect the
process.
Then it is just develop & etch. I don't know if the development needs
to be done in the dark or not. I did for the first couple of minutes.
Just don't forget to take the protective plastic layer off - it just
doesn't work that way.
-- Dave
--- In
Homebrew_PCBs@yahoogroups.com, Markus Zingg <homebrew-pcb@...>
wrote:
>
> Hi group
>
...
>
> I hope this helps others. Enjoy!
>
> Markus
>