Development of Highly Sensitive Temperature Sensor Using Ni foil

Abstract

This paper describes the development of a highly sensitive Ni foil temperature sensor. The element structure of the Ni foil temperature sensor is constructed from Ni foil with approx.3 μm in thickness bonded on to crystallized glass with epoxy resin and measures just 0.7×8.0×0.3 mm, yet its resistance value is 1 kΩ. A fine pattern is fabricated in the Ni foil using photo etching technology. The size of the sensing part of the stainless steel protective tube, which houses the Ni sensing element, is a mere, Φ1×30 mm. Optimal conditions for the main manufacturing processes of the sensor were determined by examining the crystal structure and stress on the Ni foil using an X-ray diffractometer, X-ray stress analyzer and SEM. Ni temperature sensors fabricated using these optimal conditions exhibited high sensitivity and stable performance. TCR is 6600ppm/°C between 0°C and 100°C, the same as pure Ni wire, and is stable at room temperature with a drift of ±0.005°C/year. After calibration this temperature sensor is highly accurate with a fast thermal response time. Therefore the Ni foil temperature sensor is applied to precision manufacturing, semiconductor and other industries where high accuracy is demanded.