Operation and Maintenance Manual Model 7AA Wafer Grinder
7 - 24 Version 1.2 - April 18, 1996
DETERMINING WORK CHUCK
POSITION
The work chuck position data defines the work chuck coordinate for
each grinding wheel. This data should represent the position where
the center of rotation of the work chuck is in line with the center of
the rim of each grinding wheel. This position is determined at the
factory and should not require change. In the event of removal of the
work chuck carriage servo motor the home position will require
recalibration. However, the relative positions of each work chuck
position to the home position is constant.
To determine work chuck position requires grinding a wafer far
enough off center to produce an unground circle in the wafer center.
The coarse wheel should be used for this test. By noting the work
chuck position for this test and measuring the circle diameter the
correct work chuck position can be calculated. In order to prevent
interference between the work chuck and finish wheel it is best to
use a position larger than the actual position. After completing this
test the correct work chuck position can be calculated as follows:
actual position = test position - d/2 - .062"
where d = center circle diameter in inches
After determining the correct work chuck position for the coarse
wheel the finish wheel work chuck position should be calculated
using the following formula:
finish wheel chuck pos'n = coarse wheel chuck pos'n - 3.312
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