Dear Kevin Thank you for the reply. Our major concern is the surface roughness of the cavity. I'm actually not sure about the surface finish quality of a machined cavity. But We are looking at sub-micron roughenss. Thanks Best Leo On 8/30/07, K.P.Nichols@utwente.nlwrote: > Is there any particular reason that you need to use SU-8? If there isn't, this sounds like something that could be made in a machine shop out of a wide variety of materials. You might want to consider that first, as a 700 micron "film" will give you lots of problems. -- Xiaoguang "Leo" Liu Birck Nanotechnology Center, Purdue University, 1205 W.State Street, West Lafayette, IN, 47906 USA liu79@purdue.edu