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PN 074-550-P1C
SQC-310 Operating Manual
Figure 7-5 Over/Under damped control curve (from a positive/negative step)
Continue to adjust P and I Terms alternating between 0% power in Manual
mode and Auto mode until the steady-state response is well controlled.
Ringing does not need to be completely removed during this step if the
steady-state response is smooth; preconditioning will minimize step
changes.
When finished, slowly decrease power to 0%, and then press the Stop
button.
14 Determining Preconditioning Settings
The power level recorded as PWR
0R
is the power where deposition just
begins. Use this value for Ramp 1 power in the Film Conds menu. Use a
ramp 1 time appropriate for conditioning the source type. For Ramp 2
Power, use a power value that is slightly less than PWR
DR
. This will prevent
a large step change when entering the deposition phase.
Once PID terms are established for a material, they will typically be similar for other
materials given the same system. Only the P-Term and preconditioning power
levels may need adjustment. For best results, repeat the control loop tuning for
each new material.
If adjustment to the P-Term is not sufficient for limiting response, Slew Rate can
further limit aggressive power changes. Slew rate is Power (%) of full scale per
second. At rates below 10 Å/s, a slew rate of 1-2% per second is common for
e-beam systems. Decreasing the Filter Alpha will also limit the PID control loop
response to occasional large noise spikes, such as those seen from arcing.
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