Dielectric ceramic composition and ceramic capacitor

Details Dielectric ceramic composition and ceramic capacitor Dielectric ceramic composition and ceramic capacitor

2001-06-29

2003-12-02

Brunsman, David (Department: 1755)

Compositions: ceramic

Ceramic compositions

Titanate, zirconate, stannate, niobate, or tantalate or...

C501S138000, C501S139000, C361S321200, C361S321400, C361S321500

Reexamination Certificate

active

06656865

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a dielectric ceramic composition and a ceramic capacitor fabricated using the same, and more particularly, to a dielectric ceramic composition having excellent temperature characteristics and a long life-time and to a ceramic capacitor comprising a dielectric layer formed from said composition.
BACKGROUND OF THE INVENTION
A ceramic capacitor generally consists of a sintered body in the form of a chip, and a pair of external electrodes formed on both terminals of the chip. The sintered body is a multi-layered material wherein several dielectric layers and internal electrodes are alternately laminated. In such a multilayer capacitor, adjacent two internal electrodes are aligned with one dielectric layer sandwitched therebetween and are each electrically connected to the external electrodes.
As a material for forming a dielectric layer of a ceramic capacitor, there has been hitherto employed, e.g., a reduction resistive dielectric ceramic composition comprising barium titanate (BaTiO
3
) as a major component, and a rare earth metal element as an additional component. Further, as a material for forming an internal electrode of a ceramic capacitor, a sintered conductive paste comprising, e.g., a Ni metal powder as a major component has been employed.
The sintered body of a ceramic capacitor may be prepared by overlaying a green ceramic sheet and an internal electrode pattern alternately and intimately to provide a multi-layered chip, evaporating a binder component from the chip, sintering the chip at a high temperature of about 1200~1300° C. under a non-oxidizing atmosphere and then subjecting the sintered chip to a re-oxidization under a weakly oxidizing atmosphere.
Recently, there exists a need to develop electronic parts as well as electronic machines having enhanced electrical properties. Particularly, in case of a ceramic capacitor, many efforts have been made to improve the temperature and life-time characteristics.
SUMMARY OF THE INVENTION
It is, therefore, a primary object of the invention to provide a dielectric ceramic composition having improved temperature characteristics and a long life-time.
It is a second object of the invention to provide a ceramic capacitor comprising a dielectric layer formed from the inventive dielectric ceramic composition.
In accordance with an aspect of the present invention, there is provided a dielectric ceramic composition comprising a sintered body containing ceramic particles having a core/shell structure (hereinafter, “core/shell structured particles”) in an amount of 15% or more based on the total ceramic particles of the sintered body, the core/shell structured particle being composed of a core portion, which is a BaTiO
3
crystal, and a shell portion surrounding the core, which is made of a solid solution containing BaTiO
3
as a major component.
Further, in accordance with the present invention, there is provided a ceramic capacitor comprising at least one dielectric ceramic layer formed from the inventive dielectric ceramic composition, and at least two internal electrodes between which the dielectric ceramic layer is inserted.


REFERENCES:
patent: 5790367 (1998-08-01), Mateika et al.
patent: 0877399 (1998-11-01), None

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