Dear all,

I need to make some fine structures (rectangular ridges) over PDMS using
SU8-50 as the master moulds over Glass substrates. I am able to peel off the
PDMS with the ridge structures in the first trial with the SU8 master.
However when I am trying to reuse the master again, Their is problem in
peeling off of the PDMS and it tends to tear off at the ridge corners. In
the process the Su8 also gets spoiled with the tweezers. My ridges vary from
500um to 1500um in width and are 50 um in height. I am using the same baking
conditions for PDMS every time (120C for 2.30 hrs). I have also tried to
increase the baking time for the second trial, but it still remains a
problem. Is it some residual PDMS in the first trial that is creating
problem for the 2nd run? Do I need to clean the SU8 masters every time
after molding PDMS?... I shall be highly obliged if anybody can suggest some
easy solution to this like applying some thin layer between the two layers
before pouring PDMS over SU8... etc..

Thanks in advance to all....

Debashis Maji,