The 7AA universal chuck
Design to accommodate multiple wafer sizes on the 7AA without switching chuck sizes. If the original chuck is compared to newer chuck designs almost all backgrind chucks now are made out of a solid ceramic with porous ceramic inserts. The outer edge of the wafer is supported by and area of ceramic which doesn’t apply vacuum. A few mm in from the edge the porous vacuum ring provides the vacuum to hold the wafer down on the chuck. One of the primary reasons for this was to reduce the particulates which are drawn into the porous section of the backgrind chuck and vacuum system. This type of design also reduces the amount of CFM of vacuum needed during operation and provides a more consistent vacuum.
Other advantages are:
· Less particulates on the tape or device side of the wafer.
· During flushing of the chuck less particulates are flush back on the backside of the wafer when removed by PP2.
· The TTV is more consistent over longer periods of time since less particulates are getting in the porous part of the chuck.
· Less chuck grinding less wheel wear.
The Universal chuck kit consists of the following components:
· Universal Chuck assembly
· Ceramic dressing stone
· Water Regulator and Digital gauge
· Instructions for installation
· Plumbing Diagraph 110336A1 which should be used in conjunction with the original 7AA print 110336