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Section 4: Basic measurements
Cancelling test fixture leakage current
Significant leakage in the test fixture can corrupt a resistance measurement. This leakage current can
be cancelled by performing a REL on the current component of the resistance measurement. The
following procedure assumes that steps 1 through 7 of the preceding resistance measurement
procedure have been performed. Perform the following steps to cancel leakage current:
1. With the V-source in standby, remove the DUT from the test fixture.
2. Select the amps function (I) and then disable zero check; also make sure that REL is disabled
(REL indicator off).
3. Press OPER to source the programmed V-source level to the test fixture.
4. Select the lowest possible measurement range to display the current reading; this reading is the
leakage current in the test fixture.
5. Press REL to zero the reading; this cancels the leakage current reading.
6. Press OPER to place the V-source in standby and enable zero check.
7. Perform the following steps to establish the amps REL value for the ohms function:
a.
Press CONFIG and then R to display the CONFIGURE OHMS menu.
b.
Select the AMPSREL menu item.
c.
Select YES to establish the amps REL value.
d.
Use the EXIT key to back out of the menu structure.
8. Re-install the DUT in the test fixture.
9. Select the ohms function (R) and proceed to step 8 of the resistance measurement procedure.
Resistivity measurements
The Model 6517B can make surface resistivity measurements from 103 to 1017 ohms and volume
resistivity measurements from 103 to 1018 ohm-cm.
Typical resistivity test fixtures (such as the Keithley Instruments Model 8009) use circular electrodes.
In order to use these test fixtures, the insulator sample must be large enough such that all the
surfaces of the electrodes make contact with the sample. When using the Model 8009 test fixture, you
do not have to make any calculations. For volume resistivity, you only need to know the thickness (in
mm) of the sample. The Model 6517B automatically performs the calculation and display the reading.
4-22
Model 6517B Electrometer Reference Manual
6517B-901-01 Rev. C / August 2015
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