<title>Application of composite particles to electronic devices</title>

Abstract

Electroceramic particles with electrodes of solder are prepared y a low cost and high productivity process. The electroceramic particles can be used as single particle devices, and moreover as multi-functional devices by their assembling. PTCR material is one of the electroceramics, having a positive temperature coefficient of resistivity. We prepare the PTCR particles with electrodes of solder as follows. Semiconducting barium titanate (BaTiO<SUB>3</SUB>) particles, a typical PTCR material, and solder particles are charged into a cylindrical vessel, and the vessel is rotated for several hours. The product is semiconducting BaTiO<SUB>3</SUB> coated by solder particles. The solder particles are flattened out at the surface of the core particle. The solder forms small dot-like islands, and they are isolated each other. Several applications of such kind of composite particles are described. Single particle device is a PTC thermistor, which consists of one composite particle of semiconducting BaTiO<SUB>3</SUB>. Flexible and self-thermostatic sheets can be produced by packing the composite particles between two thin electrodes. Using NTC particles instead of the semiconducting BaTiO<SUB>3</SUB> single particle devices of NTC thermistor and flexible NTC sheets can be produced. Twin particles device is a combination of a single particle PTC thermistor and a single particle NTC thermistor in series, and will be a V-type thermistor, having both PTC and NTC properties. The V-type thermistor can be obtained also by stacking the layer of PTC composite particles and that of NTC composite particles in series. It can be applied to a protective device.