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SPECTANO 100 User Manual
8.2.1
Thin film electrodes or coating
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
•
Silver coating
•
Sprayed metal
•
Evaporated metal
•
Metal spattering
For more details, refer to the international standards like ASTM D150-18 (ASTM D150-11),
D-257-14, IEC 62631-2-1-2018-02 (IEC 60250) or IEC 62631-3-1.
Note:
When attaching a thin film electrode, the gap width between the guarded thin film electrode and
the guard thin film ring should be as small as possible.
8.2.2
Guard electrodes
When measuring the dielectric properties of solid materials without guarding, the measurement is
influenced by stray capacitances at the edge of the solid test material, as shown in the following figures.
Figure 8-4
Lines of electric force, unguarded electrode
1
1. This image refers to the standard ASTM D150-11.
