Estimation of thickness, complex bulk permittivity and surface conductivity using interdigital dielectrometry

Experiments that are based on theoretical techniques for deducing continuum parameters from the gain-phase response of interdigital electrodes are described. They demonstrate the use of 50- mu m- or 1-mm-wavelength interdigitated electrodes for the absolute measurement of (1) the thickness and voidage of a layer formed by the sedimentation of 41- mu m particles in transformer oil; (2) the thickness and high-frequency bulk permittivity of plasma-deposited bromobenzene and vacuum-deposited parylene, the former in-situ; (3) the complex permittivity of transformer oil without and with a parylene passivation layer to prevent the adsorption of water; (4) the dispersion of oil-impregnated paper having a finite thickness; and (5) the surface conductivity due to adsorption of water on a silicon dioxide substrate. The frequency range for (3)-(5) is 0.005 Hz to 10 kHz. Difficulties that are apparently due to charging effects on the integrated circuitry are discussed.<
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