Homebrew PCBs

Just to report:

Someone mentioned the material advertised at:

http://renaelectronics.com/product_stencil.htm

for 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
>