Most xray film is designed to work with "screens" in a cassette. The
screens, located both on the front and rear of the cassette convert
the xrays to visible light to expose the emulsion (on both sides of
the film). There are, however, non screen films that can be exposed
by xrays directly.
Mark
At 06:59 PM 9/10/2010, you wrote:
> >I've got access to an XRay developer machine and was wondering about
> >this... The Film is pretty large so If at all possible I could make a PCB
> >1' by 1'
> >or bigger but thats the biggest size of paper we got...
>
> Maybe...
> -Since the silver halides in x-ray film retain their inherent
>blue/UV sensitivity, you'd be able to expose the film without having to
>blast them with the x-ray machine. They may also have a sensitivity to
>green or other wavelengths, see package notes regarding phosphor screens,
>etc.
>
> -Most (not all) x-ray film has a sensitized emulsion on both sides
>of the film. This helps to increase density and contrast to improve
>viewability. This may be an advantage, or may not.
>
> -X-ray film tends to be fairly high-contrast, which would be useful
>for litho masks (the thing you'll use for your pcb exposure), although it
>may not be dense/black enough.
>
> -X-ray films typically have a pretty thick substrate, which makes
>for easier handling but could cause problems with double-sided emulsions
>and fine circuit traces. If you want to remove some emulsion from one
>side, straight chlorine bleach will eat it right off developed or not.
>
> -You ∗will∗ have to experiment with both exposure and development
>times, but x-ray developer chemistry is very similar to, if not the same
>as, regular black/white film chemistry. The fixer might be a little
>stinkier. Cut up a sheet and try different exposure/development times.
>
> You'll probably get better results with clear film than any sort of
>paper.
>
> If you can get the film, especially if they toss it because there's
>a code date (it's most likely still good), give it a try. The main
>difference between x-ray and photo film is the sensitization to x-ray
>wavelengths, and I have shot 8x10 x-ray film in a big camera. It ∗did∗
>tend to be a bit grainy, so film resolution (the finest detail that the
>film can render) might come into play.
>
>∗∗∗
> Craig, I'm not sure who, if anyone, is still making litho film, but
>if you can get hold of some surplus imagesetting film it should do the
>trick. The backing tends to be thin, but it has very high resolution and
>nice density - it's litho film, after all. I have some of the red
>sensitive stuff (RLD = "red laser diode"), and dealing with the big roll
>in the dark green safelight (aka: the green darkness) is kind of a pain
>but better than total darkness.
>
> -Gary
>
>
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