Homebrew PCBs

> Leon wrote:
>
> I've just noticed something that might be
> useful to other people using pre-coated
> boards.
> 
> I was using up some rather old off-cuts
> while I waited for some new material to
> arrive, without much success. The new
> material arrived this morning and I
> noticed that the faint yellow pattern on
> the resist after UV exposure was much
> more noticeable than it had been on the
> old stock.

Leon,

At least with the brand I have they will
still work years out of date.

The issue is that they loose a lot of
sensitivity and a little bit of contrast.

As long as your photo tool is nice and
dark just try increasing the exposure
time and see how you go.  As an example
2 year out of date boards with a vellum
photo-tool will take me 10 minutes where
as fresh stock will be about 3 minutes.