| Summary: | A novel three-stage process to produce NTCR sensors is presented. In this process, an uncalcined powder mixture of NiO and Mn<sub>2</sub>O<sub>3</sub> was deposited onto an alumina substrate via aerosol co-deposition (AcD). Then, an electrode structure was screen-printed onto the surface and the composite film was sintered in a multifunctional temperature treatment. Thereby, the sintering of the electrode, the formation of the NiMn<sub>2</sub>O<sub>4</sub> spinel and the removal of film strains took place simultaneously. This enabled a significant reduction in energy demand and workload. The manufactured sensors, both as first prototypes, as well as miniaturized chip components, were characterized by a single-phase cubic NiMn<sub>2</sub>O<sub>4</sub> spinel structure, mechanical stability and electrical properties that were similar to those of classical NiMn<sub>2</sub>O<sub>4</sub> bulk ceramics or tempered aerosol deposited (AD) NiMn<sub>2</sub>O<sub>4</sub> films. Particularly noteworthy was the high reproducibility and low variation of the NTCR parameters, such as the specific resistivity at 25 °C <i>ρ</i><sub>25</sub>, the electrical resistance at 25 °C <i>R</i><sub>25</sub> and the thermistor constant <i>B</i>. The NTCR parameters were as aging-stable as for NiMn<sub>2</sub>O<sub>4</sub> bulk ceramics or tempered NiMn<sub>2</sub>O<sub>4</sub> AD-films and could even be further improved by thermal post-treatment.
|
|---|