Lidia,

I have processed SU-8 microstructures on PMMA discs without any
substantial problems. The developer did not dissolve the PMMA disc
during the development (about 6 minutes ). Still, a test has shown that
PMMA starts to get cracks if it is exposed to the standard developer
more then 30min. So, the development is complete long before any cracks
appear.

The question to be answered is the influence of the PMMAs molecular
weight to its solubility in developer. This might have a certain impact
on the selectivity during development. There is only one way to find
out: Give it a try !

Best regards,
Roger.

> ------------------------------------------------------------------------
>
> Subject:
> [mems-talk] Su-8 to PMMA selective etch
> From:
> Lidija Malic 
> Date:
> Wed, 20 Oct 2004 00:09:52 -0400 (EDT)
> To:
> [email protected]
>
>
>Hi Everyone,
>I am trying to make multimode waveguides using spin-coated PMMA as
>cladding and SU-8 as core material. I do not have much experience with
>SU-8 and I would like to know if there is a selective etchant that will
>not attack the PMMA cladding, while etching the unexposed SU-8 layer. Any
>recommendation will be of great help.
>Thanks,
>Lidia
>
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