Hi.

Do you need to pattern the top layer so that it really needs to be a
photoresist? Otherwise there are some very nice and thin epoxies that are
pretty stable in water environments. Have a look at Epoteks products.

/mikael

-----Original Message-----
From: mems-talk-bounces+evander=stanford.edu@memsnet.org
[mailto:mems-talk-bounces+evander=stanford.edu@memsnet.org] On Behalf Of
Binh Tran
Sent: Sunday, January 30, 2011 7:24 PM
To: mems-talk@memsnet.org
Subject: [mems-talk] Water resistance trouble of SU-8

Hi all,

My work is to make the biological sensor, in which the sensing part must
be immersed in the media solution for several days. I used the SU-8 2002,
2um thickness, cover on the top of gold pad to create some electrodes and
the trouble comes.

SU-8 2002 seems not stable in the aqueous environment. Some SU-8 portions
peeled off and the gold pad might contact with the media solution at the
unexpected area. They made my electrical signal goes wrong.

Does anyone have experience in photoresist in aqueous environment ? Is
there another kind of photoresist can help  ?

Thank you for reading.

Binh Tran
MS Candidate - Nano System
Kyungwon University - Korea