The thermistor is a type of sensitive component and is divided into a positive temperature coefficient thermistor (PTC) and a negative temperature coefficient thermistor (NTC) according to the temperature coefficient. The positive temperature coefficient thermistor (PTC) has a higher resistance value at higher temperatures, and the lower the resistance value of the negative temperature coefficient thermistor (NTC) at higher temperatures, they belong to the semiconductor device. The main characteristics of the thermistor are high sensitivity; wide operating temperature range; small size; easy to use; easy to process into complex shapes; mass production; good stability and strong overload capability.