Dear Bob

I have had a some success with PMMA (Perspex) substrates. I have used
the 1/8" (~3mm) sheets cut into squares. They come covered with a
protective sheet of plastic which is handy when machining the sheets to
the proper size.

1. I can't say whether the structures will stick to the substrate; our
structures float off every substrate.
2. PGMEA (the developer) doesn't seem to touch the Perspex sheets. I
have only had luck dissolving them in chlorinated solvents. I have
dissolved powdered PMMA in cyclopentanone (the solvent for the SU-2000
series) and GBL (the solvent for the other SU-8 series), though, but
the rate of attack of the solvent on the sheets appears negligible.
3. The CTE is similar (SU-8 = 52ppm, PMMA = 50-90ppm).

Plus, the substrate is transparent to our exposure wavelength (and well
into the UV), and the surface is smooth enough that it doesn't scatter
our exposure beam.

Chris

On Friday, August 29, 2003, at 11:57  pm, ROBERT DAVIES wrote:

> Hello Everyone,
>
> I am new to playing with SU-8. Rather than spin coat and process on
> silicon I wish to replace the silicon wafer with a plastic substrate
> to which the SU-8. Compatibility of the SU-8 with the plastic requires
> that:
> 1        The resist must adhere to the plastic
> 2      Solvent in SU-8  and developer must not swell or dissolve the
> plastic
> 3    Plastic should expand and contract isotropically during the
> baking and cooling processes with a similar thermal expansion
> coefficient to the SU-8 (polymerised.
>
> Does anyone out there have any suggestions about a suitable plastic ?
> If you do and it is them my life gets easier.
>
> Many thanks to you all.
>
> Bob
--
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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