PTC Ceramics, positive temperature coefficient functional ceramics, are small ceramic stones with self temperature limiting characteristics.

It has fast heating response time and plateau once the predefined reference temperature is reached.

Its resistance goes up along with the increasing of temperature to reduce the current and keep the inside ceramic plate on a constant temperature.

Above the reference temperature, the semi-conducting and ferro-electrical properties of the ceramic are utilized to produce an increase in resistance of several orders of magnitude, and hence produce its self limiting properties.

The main elements of PTC thermistor are BaTiO₃，（Pb，Sr，Ca，Ba）（Ti，Sn）O₃ and V₂O₅. Via doped and modify,

It could be made into component with relevant temperature and shape.

It has constant temperature, no over-heat, little power expenditure and safety. Hence, its application covers widely in electrical industry, medical area, home appliance, oil industry and auto test, etc.