Measurement of the thermal diffusivity of electrically nonconducting substrates

An apparatus was built up for measuring the thermal diffusivity of thin (equal or bigger than 500 mym), electrically nonconducting substrates. The apparatus is based on the method of Angström. The ratio of amplitudes and the phase difference of temperature waves at the upper and bottom side of a periodically heated substrate are measured. The detection of temperature is done by sputtered Ni-temperature sensors. Results are shown from measurements on Al2O3 and AlN substrates.