Homebrew PCBs

Investigating photo emulsions, I may have found a good way to coat 
blank PCBs with the emulsion. 

There's a device used for silkscreen preparation called a 'scoop-
coater'. These hold a small quantity of the emulsion and are drawn 
over the silkscreen frame to coat it evenly. You may need to do some 
shimming to adjust the gap between the edge of the unit and the PCB 
to get a thin coating. They're available in various lengths and are 
reasonably low in price.


Regards, Bob


--- In Homebrew_PCBs@yahoogroups.com, "hjf2k2" <drgenio@h...> wrote:
> Hi all, i've been testing a way to make photo etching cheap'n easy.
I
> went to a Screen-print shop and bought photosensitive emulsion, the
> cheapest type. I mixed the components and painted the emulsion on
the
> copper. Then I let it dry overnight in a (pitch) dark place.
> On a transparency I printed the negative of my circuit and placed
the
> transparency, toner side to the emulsion and placed it under a
> fluorescent lamp for 7 minutes or so. I removed the board and
nothing
> seemed to change, until I ran some water over the board, and with a
> hair brush  for babies (the softer-than-hair type) i helped the 
water.
> The exposed areas dried up but the rest washed with water. GREAT
> precision, SMD quality. Then I let the board again now in the sun 
to
> totally burn the emulsion and it was ready for etching, warm (hot)
> ferric chloride.
> 
> Hope that helps.
> Some day I'll try the AZO-based emulsion, but that one needs UV 
curing.