The reason of poor quality of thermistor

The application of thermistor thermistor is widely used in household appliances, electric power industry, communication, military science, aerospace and other fields, with broad prospects. What is the reason for the poor quality of thermistor?

Due to the unique grain boundary structure of thermistor, under a certain electric field, the conduction of grain boundary transiently changes from hot electron emission conduction to electron tunnel conduction, and its resistance value decreases sharply with the increase of voltage, which has excellent nonlinear volt ampere characteristics. Then, when there is over-voltage, the grain boundary electron tunnel effect can restrain the increase of over-voltage peak value and absorb part of over-voltage, so as to play a protective role for the line or equipment.

However, regardless of the application of thermistor in power lines or electronic circuits, if various types of over-voltage occur frequently, the varistor will frequently act to suppress the over-voltage amplitude and absorb and release the surge, protect the electrical equipment and components, which will inevitably lead to the performance degradation and even failure of thermistor.