How to select NTC Thermistor

The NTC meaning is a negative temperature coefficient, refers to the negative temperature coefficient of semiconductor materials or components, the so-called NTC Thermistor is a negative temperature coefficient thermistor device. It is based on metal oxides, such as manganese, cobalt, nickel and copper as a main material, and the ceramic manufacturing process made​​. These metal oxide materials have semiconductor properties, because the conductive way completely similar germanium, silicon and other semiconductor materials. The temperature is low, the number of these oxide material carriers (electron and hole) less, so its resistance value is high; as the temperature increases, the number of carriers increases, so the resistance value is lowered. The range of variation of the NTC thermistor at room temperature 10O ~ 1000000 ohms, the temperature coefficient of -2% to -6.5%. NTC thermistor are widely used for temperature measurement, temperature control, temperature compensation.

NTC is the resistance exponential relationship is reduced as the temperature rises, the phenomenon and material having a negative temperature coefficient thermistor. The material is sufficiently mixed with manganese, copper, silicon, cobalt, iron, nickel, zinc, and the like of two or more metal oxides, molding and sintering process is made of a semiconductor ceramic having a negative temperature coefficient, can be made (NTC) thermistor. Ratio, sintering atmosphere, sintering temperature, and the structural state of the resistivity and material constants with the material composition varies. Now also appears to the silicon carbide, selenium, tin, tantalum nitride, etc. as the representative of the non-oxide-based NTC thermistor material.

Most NTC thermistor semiconductive porcelain spinel structure or other structure of oxide ceramics, having a negative temperature coefficient, the resistance value can be approximately expressed as: where RT, RT0 is the temperature T, T0 when the resistance value, Bn The material constants. Ceramic grain changes due to temperature changes in the resistivity, which is determined by the semiconductor properties.