Nathan, If the design will let the silicon sag a lot, say 1 mm, when pulled by the vacuum, it will break. Usually the design is such that the oring protrudes only few tenths of a mm above the surface so the wafer will be pulled but won't break. Many chucks don't even have an oring. Just vacuum slots, radial and concentric. Since the wafer is very flat, the will be minimum or close to zero leakage between the wafer and the chuck. In any case, you want to add a liquid trap between the chuck and the pump to allow for resist or solvents that are sucked into the line to stay there so they don't reach the pump. Good luck Shay -----Original Message----- From: mems-talk-bounces+shay=mizur.com@memsnet.org [mailto:mems-talk-bounces+shay=mizur.com@memsnet.org] On Behalf Of Nathan McCorkle Sent: Friday, December 06, 2013 9:07 PM To: mems-talk Subject: [mems-talk] Vcuum chuck pressure? How to prevent wafer breaking? I am trying to build a vacuum chuck for spinning, and can't figure out if a common laboratory roughing vacuum pump would break a silicon wafer. There is some distance from the center of the chuck to the O-ring(s), but how much? And the vacuum will never apply more than 14.7 PSI (at sea level), right? This mentions silicon surviving >10000 PSI, but is that an ingot or rod or wafer, I can't tell. http://www.me.berkeley.edu/~lwlin/me119/papers/paper9.pdf -- -Nathan _______________________________________________ Hosted by the MEMS and Nanotechnology Exchange, the country's leading provider of MEMS and Nanotechnology design and fabrication services. Visit us at http://www.mems-exchange.org Want to advertise to this community? See http://www.memsnet.org To unsubscribe: http://mail.mems-exchange.org/mailman/listinfo/mems-talk _______________________________________________ Hosted by the MEMS and Nanotechnology Exchange, the country's leading provider of MEMS and Nanotechnology design and fabrication services. Visit us at http://www.mems-exchange.org Want to advertise to this community? See http://www.memsnet.org To unsubscribe: http://mail.mems-exchange.org/mailman/listinfo/mems-talk