Operations Model 6DS-SP Planarizer
2 - 32 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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