Preparation and performance of thick film NTC thermistors

The aim of this study was to produce a reliable thick film temperature-sensing NTC thermistor based on spinel type structure NiMn2O4. Screen-printing and sintering procedures have been established to produce uniform ceramic NiMn2O4 films of similar to 20 mum thickness. NiMn2O4 Source powder was synthesized by calcining coprecipitated nickel manganese oxalate and then mixed with organic components and a glass phase to produce a suitable screen-printing paste. Following optimization of the paste, dense, even films were printed onto alumina substrates. The source material and the fired films were characterized using ICP, XRD, granulometry, SEM and laser reflected surface scanning. The electrical resistance was measured as a function of temperature and the conduction mechanism was found to be consistent with a hopping model.