Conventional NTC chip is generally made of NTC thermal materials made of transition metals such as manganese, iron, cobalt, nickel and copper oxides. Due to the low volatilization temperature of these transition metal oxides, it is easy to cause the volatilization of raw material components during the sintering process, which makes the final composition, product consistency and repeatability between production batches of the product difficult to control. Therefore, the room temperature resistivity of this kind of thermal material is greatly affected by sintering temperature, sintering atmosphere, cooling rate and other processes. At the same time, the widely used NTC chip with spinel structure are prone to slow redistribution of cations in tetrahedron and octahedron, resulting in structural relaxation. This relaxation phenomenon leads to the instability of electrical properties of NTC ceramic materials, which easily leads to the aging of NTC chip and affects the performance of thermistor chip such as temperature measurement precision.

With the increasing stability requirements of NTC chip in refrigeration, air conditioning, microwave equipment, automobile, optical communication, aerospace and other industries, improve the existing component system or develop a new component system is very important. In view of the above problems, EXSENSE Electronics recommend a NTC chip with nickel magnesium zinc oxide solid solution as the main component, which is prepared by changing the content of doping elements. This NTC thermistor chip has stable performance and great reliability. The material composition of this NTC chip is: [(Ni1-xZnx)1-yMgy]1-wLiwO, wherein x=0.0001~0.4, y=0~0.6, w=0~0.1. The initial raw materials are zinc oxide ZnO and basic nickel carbonate NiCO3·2Ni(OH)2·4H2O. The preparation of NTC chip is carried out according to the following process steps:

First, the initial raw materials are mixed according to the formula of Ni0.7Zn0.3O, the zinc oxide ZnO 2.4422g and nickel carbonate NiCO3·2Ni(OH)2·4H2O 8.7775g are weighed with an analytical balance;

Second, dissolve the weighed raw materials in 15% dilute nitric acid solution respectively;

Third, mix the two prepared solutions together, and use magnetic stirring heater to stir and mix evenly, heat and dry;

Fourth, the prepared precursor powder is calcined in air at heating rate of 5℃/min, calcining temperature is 1000℃, hold for 5 hours;

Fifth, the powders synthesized by calcination are prilling with pre-prepared polyvinyl alcohol aqueous solution as binder, then pressed into blank body;

Sixth, the body is sintered in the air at the sintering temperature of 1330℃, hold for 2 hours, and the heating rate is 5℃/min to obtain the NTC thermal ceramic sheet;

Seventh, electrode paste is printed on both ends of NTC thermal ceramic sheet and cured at 600℃;

Eight, the resistance-temperature characteristics of the NTC chip obtained by dicing are measured.