Negative Temperature Coefficient (NTC) thermistors have been widely used in temperature measurement and control due to their sensitivity to temperature changes, short response time, low price, wide temperature measurement range and good interchangeability. , voltage regulation, compensation, surge current suppression, flow rate measurement and many other fields, especially with the continuous development of modern emerging industries and the continuous improvement of new product quality, the application scope of NTC thermistors is also expanding, A large number of applications in people's daily life and work.
The ceramic chip encapsulated inside the NTC thermistor is the core of this type of electronic components. This type of NTC thermistor ceramic is generally oxidized by metal oxides of several 3d transition metals such as Mn, Ni, Co, Fe, Cu and Zn. It is a kind of inorganic functional material with spinel structure as the main crystal phase, which is formed by sintering at high temperature by using semiconductor ceramic preparation technology as raw material. The behavior of the resistance of NTC thermistors despite temperature changes is generally described by the Arrhenius formula: ρ=ρ0exp(Ea/kT). In actual use, two basic electrical parameters are generally used to represent the electrical parameters of NTC thermistors: (1) ρ25 degree , which is the resistivity at 25 degree ; (2) B value, defined as B=Ea/k , which indicates how much the resistance value changes with temperature. In the actual use of NTC thermistors, manufacturers are usually required to provide resistance value and B value products with different parameters, which requires the adjustment and design of the ceramic chip formula, so a material system with different compositions has been developed. Common material systems include Ni-Mn-O, Cu-Mn-O, Co-Mn-O binary systems and ternary or even multi-element systems composed of other elements added on this basis. These material systems can form a ceramic sintered body with a spinel structure as the main crystal phase within a certain composition range and temperature, and its resistance value and thermal constant B value can be adjusted within a certain range. These rich material systems provide sufficient and diverse formula design guarantees for the actual production of different types of NTC thermistors in the industry.
