If the glass is alkali free, then it is unlikely that it will be able to
bond.  Basically, the two primary requirements for anodic bonding are:

1 - glass with an ion species (typically alkaline - Na) that can have
increased mobility when heated, and
2 - A material capable of forming an oxide (silicon becoming silicon
dioxide, for instance).

If your glass has no alkaline species, it may still contain a positively
charged ion that can be rendered mobile enough, but it is not certain.

Best Regards,
Chad Brubaker

 -----Original Message-----
From: Joachim Oberhammer
Subject: [mems-talk] Anodic Bonding Schott AF-45 to Si

anybody having tried to anodically bond AF-45 glass wafers to Si wafers?
AF-45 is alkali-free, is it thus not suitable for anodic bonding? How
does it bond compared to Corning Pyrex 7740? I heard different opinions from
experts ...