Investigation of long-term drift of NTC temperature sensors with less than 1 mK uncertainty

Long-term drift of temperature sensors is critical to applications requiring high reliability. However, documentation and knowledge regarding long-term stability is limited. Usually manufacturers promulgate drift margins down to 10-20 mK/year, while the performance of the sensors might be much better. For some advanced industrial applications, which demand drift rates down to a few mK/year, this information is inadequate. In this paper, we present our investigation of the long-term drift of a few sets of small footprint, off-the-shelf NTC (negative temperature coefficient) temperature sensors, based on an extremely stable test setup guaranteeing stability of better than 1 mK between two calibration intervals. The results show that the SMD type sensor from Murata manufacturing (NCP15XH103D03RC), intriguingly, is the most stable sensor among the sensors tested with a drift rate of 0.492 mK/year peak-to-peak. Most of the other sensors tested have drift rates of lower than 1 mK/year, making them suitable for temperature sensing applications requiring long-term stabilities in the mK range.