David,
I have tried other methods and came back to the photographic method too, overall cheaper, more reliable and faster.
I don't think you need specialized lamps or UV lamps to make this work. I use a full spectrum daylight fluorescent lamp, 15W, 16in long in a standard enclosure. This is held above a desk surface about 6inches. I have metal feet that MG Chemicals sell for this purpose, but I suspect two piles of books or a couple of pieces of 2X4 would be just as good.
For artwork, I use standard over head transparency sheets available at Office Max, Staples or similar and print direct from Eagle to my HP Laser jet. I use a small piece of acrylic sheet to hold the artwork against the board... This works just fine.
With this setup it takes between 8 and 12 minutes to expose, and is very forgiving in terms of small alignment adjustments at the start of the exposure.
I have used both positive pre-sensitised copper clad boards and negative film that is then laminated onto a blank board (slightly longer exposure needed). I use MG Chemicals products and they habve given consistent results so far.
Both methods have been extremely successful, with the pre-sensitized having slightly better results, but higher costs.
Eagle has print settings that ensure that the toner is on the right side (ie the side that touches the coating) and can also print negative artwork.
I have successfully built double sided and 6mil trace boards.
Good luck!
Mat
--- In Homebrew_PCBs@yahoogroups.com, David Griffith <dgriffi@...> wrote:
>
>
> I'm convinced now that I should give the photographic method a try and
> even try pre-sensitized boards. I'd like to do things the Right Way
> instead of going sloppo like I have been so far. That might explain my
> previous problems. Anyhow, I'll start with constructing a UV exposure
> box. The box and timer stuff seems straightforward enough, but what I'd
> really like is to make a gizmo that sandwiches the PCB and films between
> two sheets of glass or lexan. The idea is to put the things in this
> frame, adjust for registration, clamp it closed, and that's it. Insert
> into the UV box for exposure. I saw a page a couple years ago discussing
> something like this, but I can't find it anymore. Does anyone here smell
> what I'm cooking?
>
> I keep the boards small and one-sided, would a UV EPROM eraser work?
>
> --
> David Griffith
> dgriffi@...
>
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>