Study On Negative Temperature Coefficient Thermistor For Suppressing Surge Current Applies

NTC (Negative Temperature Coefficient) thermistor for inhibiting surge currentcan protect all kinds of circuit, such as conversion power supply, switching powersupply, UPS power supply, all kinds of electric heater, electronic energy-saving lamps,electronic ballast and other electronic device power supply; and can be used forprotecting all kinds of picture tube, monitor, incandescent lamp and other lighting lamps.With the fast development of modern industry and electronic industry, the demands forelectronic components are getting higher accordingly.This paper will introduce some basic process researches, which are designed toimprove the stability and reliability of this product. It covers adding some impurities(such as Co3O4, ZrO2, SiO2) to Mn-Ni-Cu-O system, which will change the surfacemorphology of the NTC thermistor for inhibiting surge current. Also, optimizing theprocessing technique of traditional NTC thermistor products is included, which canreduce the production cycle, production cost and enhance the market competitive power.This paper will present the electrical properties, surface morphology, particle size,stability and reliability of the Mn-Ni-Cu-O system added some impurities, where themain basic process researches are as follows:1、Find out different situations which are applicable to each system by testingdifferent NTC thermistor formulas with high temperature solid state reaction method,and comparing products’ stability, reliability and processing technique in each system.2、Optimize the processing technique of traditional NTC thermistor products, thuscancel the sensitization and sophisticated steps of former production process. In thisway, we can reduce energy consumption, production cycle, fund employment rate, andenhance the market competitive power.3、Test studied products properties, including maximum steady state current,maximum allowable electric capacity, temperature shock, room temperature storage,high temperature storage and so on; and compare any properties of products preparedwith different formulas and different processing techniques.4、 Discuss effects which all test item have on properties of products and characterization for properties of products.5、Add some Co3O4to Mn-Ni-Cu-O system, thus improve durability of maximumsteady state current. After1000h, the changing rate of R25is in±15%, while thechanging rate of R25in former formula is±（20~30）%.6、Add some ZrO2and SiO2to Mn-Ni-Cu-O system, thus reduce resistivity by（10~15）%. The properties of high temperature storage and room temperature storageare changed obviously.Finally, these researches improve the stability and the reliability of products byoptimizing formula system and improving processing technique, and reduce productioncost by canceling the heat treatment of chip. Improved products have made continuouslot production，all of their technical indicators meet the design requirements, and theirquality is in the leading domestic level.