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SPECTANO 100 User Manual
8.2.1
Thin film electrodes or coating
8.2.2
Guard electrodes
26
A simple solution to avoid high pressure on the material sample and to improve
the contact between sample material and electrode is the measurement with thin
film electrodes or an additional coating surface.
Thin film electrodes or a coating surface between material sample and
electrodes improve the contact which increases current flow and reduces the
signal-to-noise ratio also when using low test voltages. The measurement error
caused by the current flow along the material sample surface at the
non-contacted areas is less than using rigid metal electrodes. There are several
types of thin film electrode or coating materials, such as:
•
Metal foil
•
Conductive paint
•
Fired on silver
•
Sprayed metal
•
Evaporated metal
•
Metal spattering
For more details, refer to the international standards like ASTM D150-11 or
IEC 60250.
Note: When attaching a thin film electrode, the gap width between the guarded
ng a thin film electrode, the gap w
thin film electrode and the guard thin film ring should be as small as practical.
e and the guard thin film ring sho
des
es
When measuring the dielectric properties of solid materials without guarding, the
measuring the dielectric properti
ring the dielectric pr
measurement is influenced by stray capacitances at the edge of the solid test
asurement is influenced by stray
t is influenced
material, as shown in
material, as shown in the following figures.
hown
the f
the followin
Figure 8-4
Lines of electric force, unguarded electrode
1. This image is seen in the standard ASTM D150-1.
he international standards like AS
rnational standards
m electrode, the gap
he guard thin film ri
h thin
and
reduces the
s the
easurement error
ement error
ce at the
he
odes. There are several
re are severa
a
as:
1
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