Test Fixtures - Keithley 6517A User Manual

2.4.6 Test fixtures
Whenever possible, use shielded, low leakage test fixtures to
make precision measurements.
Keithley test fixtures
Keithley offers a variety of different test fixtures. The ones
that are typically used with the Model 6517A are described
as follows.
Model 8002A High Resistance Test Fixture — This test fix-
tures allows resistance measurements as high as 10
tures include:
• A 3-lug triax connector and dual binding posts make
connections to the Model 6517A simple.
• Two in-line DUT connection posts that are mounted on
a guard plate.
• Light-free environment for light sensitive DUT.
• Safety Interlock. When connected to the Model 6517A,
voltage cannot be sourced to the test fixture when the lid
is open.
• Screw terminal on test fixture chassis for connection to
safety earth ground.
Note: Figure 2-33 in paragraph 2.7.1 shows connections to
the Model 6517A and the equivalent circuit.
Model 8009 Resistivity Test Fixture — This test fixture al-
lows volume resistivity in the range from 10
and surface resistivity in the range from 10
Features include:
• A 3-lug triax connector and dual binding posts make
connections to the Model 6517A simple.
• Guarded electrodes that can accommodate samples up
the " thick and 4" × 4".
• Safety Interlock. When connected to the Model 6517A,
the V-Source goes into standby when the test fixture lid
is open.
• Screw terminal on test fixture chassis for connection to
safety earth ground.
Note: Figure 2-37 in paragraph 2.7.1 shows connections to
the Model 6517A and the equivalent circuit.
Custom built test fixtures
Two examples of custom built test fixtures are shown in Fig-
ures 2-16 and 2-17. The first is a dedicated test fixture to
source voltage and measure current to a single DUT (resis-
tance measurements). The second is a multi-purpose test fix-
ture that can be used to make any Model 6517A measurement.
These two examples illustrate the basic techniques that should
be applied when building a test fixture. These same basic tech-
niques should be used if you need to build a more complex test
fixture to accommodate your test measurement requirements.
The test fixture in Figure 2-16 assumes that ammeter input
LO is connected to V-Source LO inside the Model 6517A.
This LO-to-LO connection is controlled from the METER
CONNECT selection in the CONFIGURE V-SOURCE
menu (see paragraph 2.9.1).
The following requirements, recommendations and guide-
15
Ω. Fea-
lines are provided in order to build a quality test fixture that
is safe to use.
Test fixture chassis
1. The chassis of the test fixture should be metal so that it
can function as a shield for the DUT or test circuit
mounted inside. The chassis of the test fixture will be
connected to chassis ground of the Model 6517A via the
triax cable.
2. The test box must have a lid that closes to prevent con-
tact with live circuitry inside.
3 18
to 10 Ω-cm,
3 17
to 10 Ω/sq.
3. The test fixture chassis must have a screw terminal that
is used exclusively for connection to safety earth
ground.
NOTE
After building a test fixture you should
clean it (see Handling and Cleaning Test
Fixtures).
WARNING
Safe operation requires that a safety in-
terlock switch be used to place the V-
Source in standby when the test fixture
lid is open or ajar (see Interlock).
WARNING
To provide protection from shock haz-
ards, the test fixture chassis must be
properly connected to safety earth
ground. A grounding wire (#18 AWG or
larger) must be attached securely to the
test fixture at a screw terminal designed
for safety grounding. The other end of
the ground wire must be attached to a
known safety earth ground.
Front Panel Operation
2-15