Yoshi, I can't say if it is smooth enough for your particular application since I don't know it. However, it should be fairly smooth. I would etch a substrate and then evaluate it through microscope inspection and what other inspection tools you might have. If the Pyrex is not homogenous, the surface is rough, but I would think Pyrex is homogenous. Ed -----Original Message----- From: mems-talk-bounces@memsnet.org [mailto:mems-talk-bounces@memsnet.org] On Behalf Of Yoshi.Sakata_Gmail Sent: Friday, April 04, 2008 7:16 PM To: 'General MEMS discussion' Subject: RE: [mems-talk] Pyrex isotropic etching Hi Ed, Thank you for your suggestion. Is the surface etched using "BOE" still smooth enough? I will put Au electrode on the surface. Regards, Yoshi