Thin Film Electrodes Or Coating; Guard Electrodes - Omicron Lab SPECTANO 100 User Manual

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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

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

1. This image refers to the standard ASTM D150-11.

Lines of electric force, unguarded electrode

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