This sounds like normal behaviour for SU-8. On cross-linking, a lot of
stress will be in the film which would lead to bending and it can be quite
brittle if all the solvent has been baked out of it.

Things you could try are:

   less softbake to retain some solvent and improve flexibility

   over-expose with UV to ensure even cross-linking throughout the film

   a low-temperature PEB to reduce stress.

Hope that helps.

On 27 September 2011 00:08, sumit kalsi  wrote:

> Dear All,
>
> I want to use a sheet of SU8 (<=50um) in my design, hence I have used LOR
> for releasing it from the glass substrate. But after the release, SU8 sheet
> (50um) was curved and it was not flexible (it broke when i tried bringing
> the two edges of SU8 sheet square together). Is it supposed to be behaving
> this way? Has anyone had any experience on this? Thanks a ton in advance!
>
>
> Kind Regards,
> Sumit