It depends on the aspect ration you need. In both available technologies -
ultrasonic drilling and sandblasting, you will get ~45 deg or better angles.
You can DRIE but it will contaminate the system and take many hours to open.

Shay

-----Original Message-----
From: [email protected] [mailto:[email protected]]
On Behalf Of Hui Ju
Sent: Tuesday, December 12, 2006 3:17 AM
To: [email protected]
Subject: [mems-talk] etch through hole on pyrex glass

Dear Everybody,
Hello!
Does anyone know how to make holes with a diameter of about 200 microns on
pyrex glass (7740, thickness of 200 microns)? I