How to postpone turning off the work chuck or spin-station vacuum:
How to specify a duration for the blowoff:
These changes are stored as a six-digit number in Machine Variable 98, Vacuum Delays 0=No. Leading
zeros are understood, so that 501 is the same as 000501.
If the first digit is zero, do not postpone turning off the vacuum for the Left Work Chuck. If the first digit is
1 through 9, do postpone turning off the vacuum and insert a delay of this many tenths of a second between
turning off the vacuum and turning on the blowoff at the Left Work Chuck.
If the second digit is zero, retain the original Left Work Chuck blowoff duration of 0.75 seconds. If the
second digit is 1 through 9, add this many tenths of a second to the blowoff duration.
The next two digits provide the same information for the Right Work Chuck and the final two digits provide
this information for the Spin Station.
How to choose the lengths of these three delays:
Pausing the robot after it senses the wafer can be used to make sure the robot does not lift until blowoff
begins. This is the safest of the three delays to change. If the 7AF experiences robot servo faults because it
cannot lift the wafer, this is the delay to insert.
If a wafer, especially a taped wafer, refuses to lie flat when vacuum is turned off at the work chuck or the
spin station, the robot will not be able to move in and pick it up. In this situation it is necessary to postpone
turning off the chuck vacuum until the robot has already moved in. But then you must select a pause before
blowoff.
The second delay, the pause between vacuum off and blowoff on, is only needed when the vacuum off has
been postponed. The danger there is that the blowoff could begin while the vacuum has not quite been
turned off. However only a very small amount of time is needed, and a large delay serves no purpose except
to impede throughput. Furthermore, a large delay could prevent the blowoff until the robot has begun lifting.
That defeats the purpose of these delays.
The duration of the blowoff, the third delay, may be increased to insure that the blowoff remains active until
the wafer has been moved far away from the chuck. The danger of stopping blowoff too early is that the
wafer may be pulled back to the chuck. The danger of leaving blowoff active for too long a time is that
water and possibly some grind debris can be blown back onto the wafer. It is best to keep blowoff duration
to one second or less.
Experimentation has shown that certain very porous chucks are not compatible with the vacuum and blowoff
delays. These will experience a Left or Right Chuck Vacuum Abort in the grind cycle. Do not use delays
two or three with these chucks. The first delay is still available.
How to retain the original 7AF behavior and not introduce any delays:
Do not place new values into Station Coordinate Special Items D,0 or E,0 or f,0 or into Machine Variable
98.
Other Robot Macro Changes (Equipe Model 212 only)
1. A new macro named WHO has been defined. When entered from the keyboard this will display the
firmware revision of the robot controller and the 7AF software version for the macros that have been
downloaded. This macro will exist in all versions of the software starting with 5.00.
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