Research On Manufacting Process And Properties Of Starting Chips

Along with the deep research on electronic ceramic for more than half a century, Positive Temperature Coefficient thermistor appears as a novel type of semiconductor component which has temperature-sensitive characteristics(hereinafter called PTC). It is developed at the base of BaCO3 ceramic material series. Temperature compensation, over current\over heat protection, heating, degaussing, and motor starting can be realized by using PTC, which has widespread applications in household appliances(such as color TV/color monitor, refrigerators, air-conditioning, heaters, etc.), communication equipment, aerospace and other fields. In a word, PTC is another important application in electronic ceramics field besides capacitors and piezoelectric devices.Motor starting PTC pellet, which has replaced traditional starting reply, is utilized in the refrigerator motor starting circuit with so many advantages such as simple structure, no contact point, no noise, reliable work, long service life and so on.This paper presents manufacturing process of PTC pellet, failure mechanism of PTC pellet, and summarizes PTC pellet failure modes. The author proposes that crystalline grain refinement, uniform PTC pellet, dense and uniform silver electrode surface, and electrode thickness are key parameters to improve pellet quality and reliability. Firstly, through evaluation plan of material mixing, forming, sintering, chemical nickel plating and silver electrode printing, optimization of process parameter and method is decided. Meanwhile, evaluation scheme is formulated based on physical and electrical parameters. Finally, with the aid of test result evaluation, effectiveness of adjustment is judged and optimized parameter is decided. In addition, failure analysis and process parameter optimization is helpful to improve PTC pellet manufacture level and quality reliability.