Prostat PRF-922B, User Manual

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11
Rev. 2 / 3-18-2019
PRF-922B Miniature Two-Point Probe Set
charges on its surface. The Operator should also be properly grounded to avoid body charges in fl uencing
the measurement.
The metal test bed is connected to the resistance instruments posi ve (+) terminal, which provides volt-
age to the test bed during the measurement. The micro probe shielded cable with installed BNC/Banana
Adapter is connected to the resistance instruments nega ve (-) terminal. The nega ve terminal provides
the current from the DUT to the instrument circuit, which calculates and displays the resistance of the
material or DUT. Proper measurement setup is shown below in Figure 10.
Figure 10: Measurement setup for probe measurement of a material or device as described in ANSI/ESD
STM11.13
Figure 7 shows the classic setup for measurement of a material’s resistance in accordance with ANSI/
ESD STM11.12 Volume Resistance. It also provides an indica on of the material’s probable resistance to
ground (Rtg) when in use and while in contact with a grounded conduc ve surface. Note that this mea-
surement is not an actual Rtg measurement. It is simply an indica on that the material or DUT may be
Groundable, depending on its measured resistance characteris cs.
VI. Resistance to Ground (Rtg) Measurements
Rtg measurements are made on installed materials, or assemblies while used in the manufacturing pro-
cess. ESD control materials and tools are intended to func on while properly grounded. Rtg measurement
con
fi rms the material is (a) actually grounded, and (b) the total resistance of the material when grounded
is within the ESD program requirements. There are many process elements that must be con fi rmed as
grounded and within program requirements using Rtg. Examples of are:
• Floors, worksurfaces, chairs, carts
• Device trays when loaded into equipment
• Cri cal equipment parts, tools, assembly
fi xtures
• …and many others
Rtg measurements are made with the posi ve (+) instrument lead connected directly to the facility’s
equipment ground system (or auxiliary ground, if used), and the test probe connected to the instruments
nega ve (-) terminal as previously described above. During the measurement, test voltage is applied to
the ground system and current is measured on the installed material or device under test by the single
point probe.
O en, Rtg measurement is described as a “system measurement” that includes addi onal materials,
objects, devices and connec ons in series with the device under test and ground. Examples of Rtg system
measurements are described below.