LAMINATED SEMICONDUCTOR CERAMIC CAPACITOR WITH VARISTOR FUNCTION AND METHOD FOR MANUFACTURING THE SAME

摘要

A component body is obtained by alternately laminating and sintering a plurality of semiconductor ceramic layers formed of a SrTiO3-based grain boundary insulated semiconductor ceramic and a plurality of internal electrode layers. The average grain diameter of crystal grains is 1.0 ∝m or less and a coefficient of variation representing variations in a grain diameter of the crystal grains is 30% or less. To prepare the semiconductor ceramic an Sr compound, a Ti compound and a donor compound are weighed in predetermined amounts and mixed/pulverized. A calcined powder is prepared and a dispersant is added with an acceptor compound to the calcined powder. The resulting mixture is wet-mixed and a heat-treated powder is prepared. The heat-treated powder is formed into slurry and subjected to a filter treatment. The filtered slurry is used to prepare a semiconductor ceramic. The resulting laminated semiconductor ceramic capacitor has a varistor function having excellent durability, which can suppress a reduction of insulating properties and ensure desired electrical characteristics even when ESD occurs repeatedly.

主权项

1. A semiconductor ceramic capacitor, comprising:
a sintered ceramic body having a plurality of alternately stacked semiconductor ceramic layers and internal electrode layers, the semiconductor ceramic layers comprising SrTiO3, each semiconductor ceramic layer having crystal grains with an average grain diameter Dave equal to or less than 1.0 μm and a coefficient of variation CV of the grain diameter of the crystal grains of the semiconductor ceramic layer which is 30% or less, wherein CV is a ratio of a standard deviation a to the average grain diameter Dave expressed as a percentage; and external electrodes on opposite surfaces of the sintered ceramic body and electrically connect to the internal electrodes.