Thermal Treatment of Aerosol Deposited NiMn2O4 NTC Thermistors for Improved Aging Stability

This paper examines the influence of a short-term thermal treatment of aerosol deposited negative temperature coefficient (NTC) thermistor films on the NTCR characteristics and their long-term stability with different electrode materials. An aerosol deposition of a spinel-based NiMn2O4 powder on alumina substrates with screen-printed AgPd and Au interdigital electrode structures was performed. Themanufactured components of the typical size of 1206 were tempered in amoderate temperature range of 200 degrees C to 800 degrees C and aged for 1000 h at 125 degrees C in air. Based on R-T measurements in a high-precision silicone oil thermostat bath and high temperature XRD analyses, the influence of the thermal treatment was analyzed and discussed. A 60-min tempering at 400 degrees C proved to be optimal, as both the NTCR parameters and their ageing stability could be significantly improved. The findings are explained.