Properties of thin films of Kanthal

Abstract

Vacuum deposited thin films of a Fe-Cr-Al alloy known as Kanthal have been investigated for their evaporation characteristics, composition, structure and electrical properties like electrical resistivity, temperature coefficient of resistance (TCR), thermo-emf and Hall effect. Some of the results and observations have been compared with those for the films of a Ni–Cr alloy known as Nichrome which is widely used for making commercial thin film resistors. It is shown that for making thin film resistors, Kanthal is more advantageous than Nichrome in some respects. The main advantages offered by Kanthal over Nichrome are (i) longer filament source life, (ii) higher resistivity and (iii) better evaporation characteristics yielding Kanthal films with compositions close to that of the initial charge. Other electrical characteristics like TCR and thermopwer are similar for the films of both Kanthal and Nichrome. The films showed small thermo-emf. against Al contacts below 300°C. The sign of the Hall effect was positive.