Strasbaugh Operator Functions
Version 1.2 - April 18, 1996 4 - 5
WAFER TRANSPORT SYSTEM
The machine uses two send elevators and two receive
elevators coupled with a three-arm two-position pick and place
assembly to provide efficient, continuous movement of wafers
through the cycle. The transport system contains the
mechanics and necessary motors, switches and sensors to
perform its operation. The logic for the transport system
resides in the main machine control.
SEND ELEVATORS AND CONVEYOR
There are two send elevators on the machine designated "Send
Elevator #1" (elevator nearest center of machine) and "Send
Elevator #2" (elevator nearest front of machine). Upon power-
up of the machine, both elevators will raise to their upper travel
limit.
FOR RELIABLE ELEVATOR OPERATION, THE ELEVATORS
AND CONVEYORS MUST BE STOPPED BEFORE THE
OPERATOR DOORS ARE OPENED.
Either or both elevators(s) may be loaded with a cassette which
is either completely or partially filled. The cassettes are
serviced in the order that they are placed on the elevators.
Upon start of an auto cycle, the first elevator will begin moving
down. The machine control checks the elevator's wafer sensor
every 3/16" to see if a wafer occupies that slot. If the slot is
vacant, the elevator continues down to examine the next slot.
When a wafer is sensed, the send conveyor is turned on and
the wafer is transported to the pick-up station. When an
elevator has reached its lower travel limit - that is, all slots are
empty - the elevator will raise to its upper travel limit. The other
elevator, if loaded with a cassette, will then go through the
same routine. This cycle will continue until there are no
cassettes in place or the auto cycle is halted.
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