Hi
The Pyrex wafer probably stick because the surface is too good and too
clean. Try to use graphite instead of the other Pyrex. The roughness is
caused by attack of sodium that is formed on the surface during the anodic
bonding.

Shay

-----Original Message-----
From: [email protected] [mailto:[email protected]]
On Behalf Of Roger Shile
Sent: Wednesday, June 18, 2008 6:41 PM
To: [email protected]
Subject: [mems-talk] Pyrex wafers sticking together during adodic bond

After anodic bond we had an undesirable roughness or white material on the
surface of the bonded Pyrex.  A solution to this problem was to place a
second Pyrex wafer on top of the Pyrex being bonded.  This technique worked
well for several years, but recently the two Pyrex wafers have been bonding
together.  We're using a Suss BA6 bonder 350-400 degC, 1,000 volts.  (We've
recently switched from Pyrex to
Borofloat.)

Can anyone suggest a way to prevent the glass wafers from sticking together,
or alternatively another technique to prevent the unsightly residue on the
surface of the bonded Pyrex?

Roger Shile