1. Field of the Invention
The present invention concerns a dielectric ceramic composition mainly comprising barium titanate (BaTiO3) and a multi-layer ceramic capacitor using the same and, particularly, a multi-layer ceramic capacitor having internal electrodes formed of Ni or an Ni alloy and an electrostatic capacity with less temperature dependence.
2. Description of Related Art
For multi-layer ceramic capacitors used for electronic equipment such as portable equipment and telecommunication equipment, demand for reduction of size and increase of the capacitance has increased more and more. Such small-sized multi-layer ceramic capacitors having large capacity includes a multi-layer ceramic capacitor in which the internal electrode is constituted with Ni, for example, as shown in JP-A-2001-39765. Such a multi-layer capacitor can provide a multi-layer capacitor that satisfies an X7R property (satisfying the rate of permittivity change within ±15% within a temperature range of from -55° C. to 125° C. with 25° C. as a reference), having a permittivity of 2500 or higher, and having excellent reliability even when it is lamellated.
However, reliability under severe circumstances has been required in recent years for such multi-layer ceramic capacitors depending on the application use. For example, the multi-layer ceramic capacitors have been used for car-mounted electronic equipment such as electronic engine control units and anti-lock brake systems mounted in engine rooms of cars. In such car-mounted electronic equipment, since a stable operation is demanded under conditions of a low temperature lower than −20° C. or higher than +130° C., good temperature stability even under such conditions has been required also for the multi-layer ceramic capacitors used for the car-mounted electronic equipment.
For coping with such a demand, a dielectric ceramic composition and a multi-layer ceramic capacitor satisfying the X8R property (rate of permittivity change within ±15% within a temperature range of from -55° C. to 150° C. with 25° C. as a reference) are proposed in, for example, JP-A-2005-272263.
However, the dielectric ceramic composition and the multi-layer ceramic capacitor described above involved a problem that a sufficient specific resistance can not always be obtained in a case of further reducing the thickness of dielectric ceramics between internal electrodes for further reducing the size and increasing the capacitance. Particularly, they involved a problem that the specific resistance is not sufficient under a high temperature circumstance exceeding 125° C.