Dear Suitto

I have had some success at longer wavelengths by mixing in a
sensitiser. I have had some experience with perylene, an inexpensive
polycyclic aromatic hydrocarbon (PAH). I would start with about 0.1-1
wt% perylene. Using the 435 nm line of a mercury lamp, these became
insoluble at exposures between 300 and 600 mJ/cm2 for a film ~20 um
thick.

Perylene absorbs about a third as much light at 400 nm as 435 nm, so
there may be a more suitable sensitiser for your application (check out
naphthacene or pyrene).

Good luck,

Chris

On Monday, April 12, 2004, at 11:44  am, suitto kk wrote:

> Dear Mems-talk,
> I would like to ask if anyone have experiences with
> recording using laser lithography at 400nm? Although the
> SU-8 specs says absorbance starts below 370nm, we found
> that the recorded structures become a featureless mass
> after PEB and development. Would be great if someone can
> offer some insight. Thanks for reading.
>
> suitto
--
Christopher F. Blanford
Inorganic Chemistry Laboratory, South Parks Road, Oxford, OX1 3QR, UK
Phone: +44 (0)1865 282603; Fax: +44 (0)1865 272690
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