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PN 074-550-P1C
SQC-310 Operating Manual
NOTE: TIME
SR
is typically 0.2 to 1 seconds for e-beam evaporation, 5 to 20
seconds for thermal evaporation.
When finished, slowly decrease power until there is no rate.
12 Determine the Dead Time
Slowly increase the power (%) until the desired Rate (
Å/s) is achieved.
Quickly adjust Power by 1 to 2% and measure the time between when the
power is changed and when a change in rate is observed.
The time between the change in power and when the rate starts to change
is the Dead time or D-Term parameter.
NOTE: It is common for the Dead Time of a fast source, such as an e-beam to
be very small and possibly immeasurable. In this case, the Dead Time
can be considered to be zero.
When finished, slowly decrease power to 0%.
13 Finalize Adjustments to PID Values according to control response
Set source control from Manual to Auto to activate PID control and observe
the power. The power should rise from 0% and stabilize near PWR
DR
.
If there is more than 10% overshoot in power or if the curve appears
under damped, lower the P-Term. If the time to reach PWR
DR
is
very slow (over damped), increase the P-Term (see Figure 7-5.)
A lower I-Term will increase response for over damped sources. A
higher value may reduce ringing and rate deviations seen with
under damped sources (see Figure 7-5.)
The D-Term should not need much adjustment, but if under damped
behavior is observed, increase the value. If it appears over damped,
decrease the value (see Figure 7-5.)
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