INFICON Maxtek PM-700 Plating Monitor - Manual (Page 31)

PM-700 SERIES PLATING MONITOR
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4.4.2.1.2 Sample
This mode is used to increase the crystal's range. In the Sample mode the plating
rate is monitored on a sampled basis. Between samples the rate established during
the last sample is displayed and the displayed thickness value is increased at the
displayed rate to show the assumed substrate thickness buildup. Plating of the
probe crystal is halted by applying enough deplating current to the crystal to hold
the plating rate at zero. Should the Probe fail, the failure will be enunciated, but
the displayed thickness will continue to increase on the basis of the last valid rate
sample. Parameters are provided to allow the user to set the duration of the
sample period and the interval between sample periods.
4.4.2.1.3 Sample with Deplate
This mode is identical to the Sample mode except that the Probe crystal will be
electrolytically deplated between samples. The amount of deplating is established
by the user as a percentage of the amount plated during the sample. The rate of
deplating is set by the amount, which must be deplated, and the time between
samples.
4.4.2.2 Dual Probe Measurement Modes
The following measurement modes require two probes and, therefore, require the
use of a Dual Probe model.
4.4.2.2.1 Auto Probe Swap
The Auto Probe Swap mode can be applied to all three of the Single Probe
measurement modes. In the Auto Probe Swap mode a second probe is installed in
the bath. While the active probe monitors the bath, the second probe is held in
standby. In the event of a failure of the active probe, the monitor will auto-
matically switch to the second, or standby, probe. If the standby probe requires
initializing, it will be initialized with a preplate cycle, prior to the swap. During
the time it takes the unit to switch over to the second probe, the rate display is
held at the last valid rate value and the displayed thickness continues to buildup at
the displayed rate.
4.4.2.2.2 Alternating Measurement mode
In this mode two probes are used to provide continuous monitoring. Usage of the
two probes is alternated. While one probe is monitoring the bath the second probe
is being deplated. The percentage of deplate between plating cycles is established
by the user. The rate at which the two probes are alternated is determined by the
Sample Interval parameter. The alternate probe is changed back to the plate mode
10 seconds before the probes are switched. This is done so when the probes are
switched, the plating rate is stabilized on the new probe. In the event that one of
the probes fails, the monitor reverts to the single probe Sample with Deplate
mode.
4.4.2.2.3 Dual Probe Measurement mode