At that  thickness, 400+ microns, you may not want to use resist to do molding.
Even the thickest SU-8 will probably not spin-coat to 400 microns with decent
uniformity (at least that is my experience with thick SU-8).  If you insist on
using SU-8, then you will likely have to use the thickest SU-8 available (see
Microchem.com) and spin-coat multiple layers.  Keep in mind that the SU-8 will
be very difficult to deal because of its extremely high viscosity (it will
probably be worse than honey).  You may want to consider etching silicon molds
with DRIE, which will allow you to etch as deeply as you want into a silicon
wafer in a relatively short time span.

David Fozdar

University of Texas at Austin
Department of Mechanical Engineering
Center for Nano Molecular Science and Technology (CNM)

Quoting "Peng Li (Paul)" :

> Dear all,
>
> Where can I find some detailed information about high aspect SU-8 molding?
> I find I have to do multi-layer molding if I want to make mold depth
> larger than 400um.