Electricity: electrical systems and devices – Electrostatic capacitors – Fixed capacitor
Reexamination Certificate
2000-08-18
2002-04-09
Dinkins, Anthony (Department: 2831)
Electricity: electrical systems and devices
Electrostatic capacitors
Fixed capacitor
C361S310000, C361S321400, C361S321500, C029S025410
Reexamination Certificate
active
06370014
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a monolithic ceramic electronic component such as a laminated capacitor, and a method for manufacturing the same. In more detail, the present invention relates to a monolithic ceramic electronic component having a structure in which the adhesion between internal electrode and ceramic has been improved, and a method for manufacturing the same.
2. Description of the Related Art
Monolithic ceramic electronic components comprise a structure in which one or more internal electrodes are disposed within a sintered ceramic body. Monolithic ceramic electronic components known in the art include a laminated capacitor and laminated ceramic multilayer substrate.
A sintered ceramic body in which ceramic layers are laminated via internal electrodes is used for a monolithic ceramic electronic component. Adhesion between the internal electrode and the ceramic layer is aggressively required to be high in this sintered ceramic body. When the adhesive property between the ceramic layer and internal electrode is insufficient, an interlayer peeling phenomenon called delamination occurs, or a plating liquid invades the ceramic sintered body while forming external electrodes, sometimes resulting in peeling between the internal electrode and ceramic.
Occurrence of delamination as described above causes a decrease of insulation resistance, or deterioration of electrical characteristics required for use as electronic components such as capacitors.
Accordingly, various methods for improving the adhesive property has been attempted including forming perforation holes through the internal electrode to enhance the adhesive property between the ceramic layers at the upper and lower parts of the internal electrode, or mixing the same ceramic material as used in the ceramic sintered body into an electrode paste for forming the internal electrode to allow the ceramic in the internal electrode to diffuse toward the ceramic sintered body during firing.
However, the shape of the internal electrode turns out to be complicated in the ceramic electronic components manufactured by forming the perforation holes through the internal electrode, thus failing to obtain sufficient electrical characteristics.
Although the adhesive property between the internal electrode and ceramic is enhanced to some extent when the ceramic has been mixed with the internal electrode paste to allow the ceramic to diffuse toward the ceramic sintered body during firing, the adhesion between the internal electrode and the ceramic has been not always sufficient.
SUMMARY OF THE INVENTION
Accordingly, the object of the present invention is to provide a method for manufacturing a highly reliable monolithic ceramic electronic component in which the adhesive property between the internal electrode and the ceramic is effectively enhanced to decrease the occurrence of the interlayer peeling phenomenon such as delamination, and a method for manufacturing the same.
In accordance with the first aspect, the present invention provides a method for manufacturing a monolithic ceramic electronic component comprising the steps of: preparing a non-fired ceramic green chip comprising at least one layer of an internal electrode while containing a metallic compound that forms a compound by forming a solid solution with or by reacting with the internal electrode during firing; firing the green chip to allow the metal constituting the metallic compound to form a solid solution with the internal electrode or to react with the internal electrode to form a compound; and forming external electrodes on the outer surfaces of the sintered body.
In a second aspect, the present invention also provides a method for manufacturing a monolithic ceramic electronic component comprising the steps of: preparing a non-fired ceramic green chip comprising at least one layer of internal electrodes while containing a metallic compound that segregates on an internal electrode or at the periphery the internal electrode during firing the internal electrodes; obtaining a ceramic sintered body by firing the ceramic green chip while allowing the metallic compound to segregate on an internal electrode or at the periphery of the internal electrode; and forming external electrodes on the outer surfaces of the sintered body.
In the present invention according to the first and second aspects, the metallic compound containing a metal that forms a solid solution with the internal electrode or reacts with the internal electrode to form a compound, or a metallic compound that segregates on or at the periphery of the internal electrode is allowed to contain during forming internal electrodes in the ceramic in the step for preparing the ceramic green chip, thereby enhancing adhesive property between the internal electrode and the ceramic.
Although the method for manufacturing the ceramic electronic component according to the first and second aspects of the present invention can be applied for manufacturing various laminated ceramic components without any restrictions, it may be applied in the method for manufacturing a ceramic capacitor according to a specified aspect of the present invention. The ceramic green chip to be used in obtaining a laminated ceramic capacitor comprises a plurality of the internal electrodes being laminated via the ceramic layer, and has a structure in which the plural internal electrodes alternately extend along the direction of thickness to a pair of the end faces of the ceramic green chip in opposed relation one another.
The present invention also provides a monolithic ceramic electronic component obtained by the method for manufacturing the monolithic ceramic electronic component according to the present invention, comprising: a ceramic sintered body; at least one layer of internal electrodes disposed within the ceramic sintered body; and external electrodes formed on the outer surfaces of the ceramic sintered body and electrically connected to the internal electrodes, wherein the metal constituting the metallic compound contained in the ceramic forms a solid solution with the internal electrode or reacts with the internal electrode to form a compound in the ceramic sintered body.
The present invention further provides a monolithic ceramic electronic component obtained by the method for manufacturing the monolithic ceramic electronic component according to the present invention, comprising: a ceramic sintered body; at least one layer of internal electrodes disposed within the ceramic sintered body; and external electrodes formed on the outer surfaces of the ceramic sintered body and electrically connected to the internal electrodes, wherein the metallic compound contained in the ceramic sintered body is segregated on the internal electrode or at the periphery of the internal electrode.
Examples of the monolithic ceramic electronic component according to the present invention may include, without being restrictive, a monolithic ceramic electronic component wherein a plurality of the internal electrodes are disposed so as to be laminated along the direction of thickness via the ceramic layer, the internal electrodes being alternately extending along the direction of thickness to end faces of the ceramic green chip in opposed relation one another, and wherein a pair of the external electrodes are formed on the end faces of the ceramic sintered body in opposed relation one another.
Details of the embodiments according to the present invention will be described hereinafter.
First Embodiment
A non-fired ceramic green chip is prepared at first in the method for manufacturing a monolithic ceramic electronic component according to the first embodiment of the present invention. The non-fired ceramic green chip comprises at least one layer of the internal electrodes as well as a metallic compound containing a metal that forms a solid solution with the internal electrode or react with the internal electrode to form a compound during firing.
Electrode materials constituting the internal electrode are
Dinkins Anthony
Murata Manufacturing Co. Ltd.
Ostrolenk Faber Gerb & Soffen, LLP
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