Maintenance Model 6DS-SP Planarizer
4 - 16 Version 4.0 - February 1998
SPINDLE DOWN FORCE ASSEMBLY
The spindle raise force assembly function is determined by springs located inside
the raise force air cylinder. The springs move the piston which retracts the air
cylinder rod, pulling on the back end of the lever arm. The lever then raises the
spindle.
The spindle down force assembly consists of the spindle drive assembly, a lever
arm, an air cylinder, a load cell, and an electro-pneumatic regulator. (This
structure is identical for both the left and right spindles.)
The air cylinder is the origin of the force applied to the spindle drive assembly and
wafer carrier. A series of connecting rods and a lever arm transmit the force of the
air cylinder to the spindle drive assembly. The load cell senses the amount of
applied force on the spindle drive assembly and wafer carrier and generates an
analog voltage signal proportional to the amount of force. This signal is amplified
and transmitted to the control computer through an analog input channel. The
control computer receives the information and compares it to the programmed
value of required spindle down force. The control computer regulates the applied
force by regulating the air flow to the air cylinder with the electro-pneumatic
regulator. The control computer generates an analog voltage signal for the electro-
pneumatic regulator, and the regulator adjusts the air pressure in proportion to the
voltage level of the signal. Together the control computer, load cell, and electro-
pneumatic regulator form a closed loop controller to maintain the downward
spindle force within 2% of the programmed force value in pressure mode.
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