Appendix 3 Unstable Measurement Values
A7
Appendix
(10)Non-Four-Terminal Measurements
The four-terminal method requires that four probes be connected to the
DUT.
By measuring as shown in Fig.10, the measured resistance includes that
of the contacts between the probes and DUT. Typical contact resistance
is several milliohm with gold plating, and several tens of milliohm with
nickel plating. With measurement values of several k this would not
seem to be a problem, but if a probe tip is oxidized or dirty, contact resis-
tance on the order of a k is not unusual.
To maximize the opportunity for proper measurements, emulate the four-
terminal method as close as possible to the contact points of the DUT.
(Fig.11)
Figure. 10 Two-Terminal
Measurement
Figure. 11 Four-Terminal
Measurement
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