I've found getting good resolution challenging even with a decent mask
aligner.

Good mask contact seems to be the main problem due to the edge bead and the
challenge of getting a perfect, defect free film. Maybe this is your problem
rather than the lamp?

As for your home made aligner, getting an i-line filter and an IR filter
(which would remove the heating problem) is worth considering. I once had a
very good lamp with such filters from Tamarack Scientific but they've
discontinued the smaller version and the higher power lamp they sell is
expensive.

For LED sources, Michael Breadmore's work may provide ideas (see:
http://pubs.rsc.org/en/Content/ArticleLanding/2008/LC/b800465j) but they are
focussing the LED for writing lines rather than mask exposure. Getting
enough power and collimation for mask exposures may be tricky but LEDs are
now being used in commercial systems so I guess it's possible.


On Fri, Feb 11, 2011 at 01:39, Yu Huang  wrote:

> Need suggestion on UV source making su-8 master, better to be LED.
>
> Guys. I'm having difficulty getting ultra-fine feature of su-8 master using
> our UV-aligner. We have been making features ~40 microns with no problem.
> But when I push the limit to ~10 microns, it is very difficult with our
> home-made aligner, often resulting either cracking or un-crispy structures.
> The UV source is especially lousy. The intensity is neither uniform nor
> well-focused, and generates too much heat. Can anyone recommend a good UV
> source? I was hoping any LED lamp can be used. Our layer is thin, so won’t
> need too much energy output.
>
> Thanks a lot!
>
> --
> Yu Huang
> Materials Science Program
> NITRO, Biomedical Enigineering Department
> University of Wisconsin-Madison