Hi Gareth, Jianhua, Silvan and others,
Thanks for all your comments and suggestions.  I have previously made =
SU-8 structures using combinations of Omnicoat, SU-8 2002, 2005 as seed =
layer and then built thicker SU-8 structures on them up to a total =
thickness of 150um without any delamination.  My dehydration process =
were as Gareth suggested.
=20
However the above were all done on SiO2 wafers. I have not tried these =
process on glass though.  Will try and let you know.
=20
Jeffrey

________________________________

From: mems-talk-bounces@memsnet.org on behalf of Jianhua Tong
Sent: Tue 10/16/2007 4:07 AM
To: gjenkins@f2s.com; General MEMS discussion
Subject: Re: [mems-talk] SU-8 on glass



if you just want to make a mold to fabricate some PDMS structure, you =
can make a
seed layer use SU8-5, or SU8-10.
Spin SU8-5 to form a 3-4 microns layer, bake, and expose to UV(without =
mask),
postbake, and develop, then bake it in oven at 175C for 2 hours. Then =
you can
spin and pattern other thick SU8 layer without adhesion problem.

Quoting Gareth Jenkins :

> Omnicoat is certainly a good idea but good adhesion is also possible
> with the following steps:
>
> Treat with conc. H2SO4 (I find this as good as Piranha and safer /
> more eco-friendly since you don't need to make it fresh each time).
> Thoroughly dehydrate. 200-220C for 30mins on a hotplate.
> Ensure even and complete crosslinking with a higher exposure dose than
> recommended.
> Take account of stress during the PEB. If large areas are being
> exposed, consider stress relief structures in the design. A lower
> temperature PEB for longer time can greatly reduce delamination
> effects.