LAMINATED AND GRAIN BOUNDARY INSULATED TYPE SEMICONDUCTIVE CERAMIC CAPACITOR AND METHOD OF PRODUCING THE SAME.

摘要

A laminated and grain boundary insulated type semiconductor ceramic capacitor which normally works as a capacitor absorbing noises of low voltages and noises of high frequencies and works as a varistor when high voltage pulses or static electricity noises are applied thereto. The material of the ceramic capacitor is chiefly Sr(1-x)CaxTiO3 by which the material and the internal electrode material can be baked simultaneously in the process of production. A method of producing the same is also disclosed. The reason why the both materials can be simultaneously baked is as follows. A component for changing a material into a semiconductor is added to a Ti-excess of Sr(1-x)CaxTiO3; Mn and Si components are further added which turn into MnO2 and SiO2 respectively during the step of baking; and accordingly grain boundary insulated semiconductor for capacitors is easily obtained only through re-oxidation without the conventional step of surface diffusion of metal oxides. Further, according to the invention, the compact after lamination is calcined in advance in the air to obtain a laminated ceramic capacitor with a varistor function. Problems such as breakage in the internal electrode, delamination, cracks, low density after sintering, and nonhomogeneity of structure of the sintered body are suppressed as far as possible. The capacitor exhibits remarkable improvement in electric characteristics such as capacity, voltage non-linear exponential alpha , varistor voltage and in reliability. The invention exhibits the greatest features in the material composition and process in regard to the above two points.