Wheel Wear Detection
Wheel wear measurement and functionality has been expanded. The exact behavior is different if the machine
is set for grinding AlTiC and alternative materials (Machine Variable 82, ATC Grinder) or its default state,
silicon grinding. The conditions that are detected will be identical, but in the case of silicon grinding, the
operator information is presented as a warning, asking that maintenance be notified, but to continue grinding.
When the conditions are detected while grinding alternative materials, a strong message is presented to
change the wheel, the send cassettes are disabled and the turrets are locked to prevent additional material
being presented to the machine. The condition is cleared in both cases by changing the offending wheel.
Wheel wear is now checked every time material is ground on the right work chuck. Wheel wear
measurements only use the right probe and reference data. As in previous releases, the amount of wheel wear
is compared to the Machine Variables Coarse Wear Lim microns (variable 25) and Fine Wear Lim
microns (variable 35). If this amount is exceeded, a wear limit message is put on the screen. In the case of
AlTiC and alternative materials grinding, the send cassettes are disabled and the turrets are locked.
A new optional check is made, wheel wear per wafer. This is set with Machine Variables Coarse Max
Whl/Wafer (variable 26) and Fine Max Whl/Wafer (variable 36), with the default, 0.0, turning off the
check. Set the maximum amount of wheel wear per wafer allowed (microns) in these variables. The
comparison value is cleared every time the Main Menu is traversed. Therefore, the first wafer will provide a
“mark” for the current amount of wheel wear and subsequent wear (at the right chuck only) will be compared
to the last grind (or “polish”). ). If this amount is exceeded, a wear per wafer limit message is put on the
screen. In the case of AlTiC and alternative materials grinding, the send cassettes are disabled and the turrets
are locked.
Also, Wheel Wear is now reported via GEM. Variable ID number 139 is used to report Coarse Wheel Wear
and Variable ID number 140 is used to report Fine Wheel Wear. Because the numbers can be undefined, the
value of -1.0e6 is the value signifying an undefined response. An undefined response is usually due to the
wheel being unreferenced.
Dress Frequency
The entry “Dress Frequency” in the wheel dress recipes has been implemented. Setting this number to 0 will
disable the feature. The exact behavior is different if the machine is set for grinding AlTiC and alternative
materials (Machine Variable 82, ATC Grinder) or its default state, silicon grinding. On starting a machine
from being upgraded, this value should be actually entered for both the coarse and fine wheel recipes. This
will confirm the correct entry, reset the count and store the correct state in the recipe.
After the given number of wafers, a wheel dress message will be issued. In the case of AlTiC and alternative
materials grinding, the send cassettes are disabled and the turrets are locked.
Fine Polish Capability (Force Profile Grinding)
For grinding AlTiC and alternative materials (Machine Variable 82, ATC Grinder), a new mode of operation
has been implemented for the fine grind/polish step. If in AlTiC mode, the Edit Recipe Screen will label the
Fine recipe side as “Force in LBS.” The three steps are now programmed for force, not target thickness!
The Lift step is still programmed in the number of microns to lift after the dwell step.
The sequence for fine grind/polish will now approach the wafer as before, but will feed at the step “rate” until
the programmed force is achieved. Then the next feed rate will be used until the next force goal is reached.
After the step 3 force goal is reached, the force is reduced to the Fine Dwell LBS (variable 55) and the dwell
step is completed.
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