**3.1 Microwave sintering of NTC thermistor ceramics**

Because of integrity and uniformity of microwave heating, the NTC thermistors of depending on uniformity and densification may show uniform microstructure during microwave sintering. A dense microstructure is necessary to obtain a good reproducibility of the electrical characteristics of the ceramic[7]. During microwave sintering, in addition to heating, the rise in temperature is accompanied by an increase in grain diameter and a consequent decrease in the porosity during densification[8].Consequently, microwave sintering can enhance the densification and improve uniformity of NTC thermistors.
