Thermal and Electrical Characteristics of Thick Film Overcurrent Protector with Self‐recovery

Abstract

A thick film overcurrent protector with self‐recovery has been developed using carbon black graft polymer. Carbon black graft polymer, henceforth called CG, is a thick film PTC thermistor material in which a polymer forms a three‐dimensional network structure around carbon blacks by graft‐copolymerising vinyl monomers. Since the CG material gives a large and stable positive temperature coefficient of resistance depending on the copolymer material, due to the difference of thermal expansion coefficient between carbon blacks and polymer, the stable thick film overcurrent protector with self‐recovery can be realised by using the CG material. The overcurrent protector utilises the dynamic current‐time characteristics of the CG element. When a very large current flows through the CG element, the temperature rises by self‐heating, and the resistance of the element increases dramatically; as a result it restrains the current at a lower level. Since this element is not destroyed after excess current flow, it can be used repeatedly, unlike a metal fuse. In this paper, the manufacturing process and thermal and electrical characteristics of the CG overcurrent protector are investigated, including an analysis of these characteristics.

Citation

Sorimachi, Y., Tsubata, I. and Miyauchi, S. (1988), "Thermal and Electrical Characteristics of Thick Film Overcurrent Protector with Self‐recovery", Microelectronics International, Vol. 5 No. 1, pp. 42-45. https://doi.org/10.1108/eb044309