Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

Hello all!

Searched part of the archives (this search engine isn't real good)
and couldn't find assistance with the folowing:

I've recently started using photoresist after using toner transfer
and plotting direct plotting since I finally have to use SMDs and
double sided PCBs. Did my first test run today and have a few questions:

Once I peeled off the backing paper, I found that the edge of the
board wasn't covered in photoresist - in some places a strip of up to
an inch of copper wasn't covered in resist. Is this normal??

I presume that if the exposure time is correct then once developed
you get clean copper where etching is to occur? My test board on the
longest exposure time I've tried (~8mins) still had a touch of green
on the etched areas of the board and they handn't appeared to be
touched when I etched in Amonium Persulphate.

Is the resist still UV sensitive post developing in sodium
metasillicate?

Should I etch in low-light conditions or once developed I can the
etch in 'normal' bright sunlight and/or leave lying around in
sun/florescent lighting for a couple of hours before etching?

Thanks for your help

Trev.

By the way - I'mm currently printing my artwork via Lexmark inject
to two copies of acetate transparencies. Matching both copies of each
side then exposing using a 2nd hand UV light box and through a glass
sandwich. ie glass, 2 x component artwork, PCB, 2 x solder side
artwork, glass, UV lightbox. The glass sheets I'm using don't
actually fit in the lightbox, so I'm resting them on the lip of the
box which moves the artwork about 1 inch above the box's glass surface.

I'm thinking of using tracing paper primarily for cost reasons
though - any thoughts??