Electricity: electrical systems and devices – Electrostatic capacitors – Fixed capacitor
Reexamination Certificate
1999-04-29
2001-02-20
Kincaid, Kristine (Department: 2831)
Electricity: electrical systems and devices
Electrostatic capacitors
Fixed capacitor
C361S306300, C361S309000, C361S310000
Reexamination Certificate
active
06191932
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a monolithic capacitor, and more particularly, relates to a monolithic capacitor which is effectively applicable for use in a high-frequency circuit.
2. Description of the Related Art
A conventional type of monolithic capacitor relating to the present invention is described in Japanese Unexamined Patent Publication No. 2-256216, etc. This type of monolithic capacitor has an arrangement in which an equivalent series inductance (ESL) is reduced for use in a high-frequency band.
In this arrangement, a plurality of first and second internal electrodes, each of which is mutually opposing through a specified dielectric layer, respectively form a plurality of extensions, which are extended onto at least one of the two opposing sides of a capacitor itself so as to form external terminal electrodes corresponding to the respective extensions; and the external terminal electrodes are disposed on the sides of the capacitor in such a manner that a plurality of first external terminal electrodes connected to a plurality of the extensions of the first internal electrode and a plurality of second external terminal electrodes connected to a plurality of the extensions of the second internal electrodes are alternately positioned.
For instance, when current flows from the first external terminal electrodes to the second external terminal electrodes, magnetic flux, the direction of which depends on the current direction, is induced; thereby, a self-inductance is produced. However, as described above, since the respective first and second external terminal electrodes are alternately positioned, the magnetic flux induced by the current is effectively offset in parts where the first and second external terminal electrodes are located adjacent to each other so that occurrence of magnetic flux can be reduced, resulting in reduction in equivalent series inductance.
On the other hand, the arrangement above has a problem: since no external terminal electrodes are positioned on two opposing end faces of the capacitor, it is expected that there is substantially no offset effect of magnetic flux near the two end faces, thus causing a hindrance to a further reduction in ESL.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an improved monolithic capacitor, which can more effectively achieve reduction in ESL.
This invention provides a monolithic capacitor including a body of a rectangular-parallelepiped form defined by a length dimension, a width dimension, and a thickness dimension: having (1) a first main surface and a second main surface which are mutually opposing and defined by the length dimension and the width dimension, a first side and a second side which are mutually opposing and defined by the length dimension and the thickness dimension, and a first end face and a second end face which are mutually opposing and defined by the width dimension and the thickness dimension, in which the length dimension is longer than the width dimension; (2) a plurality of dielectric layers extending in the direction of the main surfaces; and (3) at least one pair of a first internal electrode and a second internal electrode mutually opposing through a specified dielectric layer so as to form a capacitor unit.
In order to solve the problem described above in the conventional art, this monolithic capacitor provides the following arrangement:
The first internal electrode forms a first extension which is extended onto at least one of the first side and the second side and a second extension which is extended onto the first end face; a first external terminal electrode which is electrically connected to the first extension is disposed on at least one of the first side and the second side onto which the first extension is extended; and a second external terminal electrode which is electrically connected to the second extension is disposed on the first end face onto which the second extension is extended.
The second internal electrode forms a third extension which is extended onto at least one of the first side and the second side and a fourth extension which is extended onto the second end face; a third external terminal electrode which is electrically connected to the third extension is disposed on at least one of the first side and the second side onto which the third extension is extended; and a fourth external terminal electrode which is electrically connected to the fourth extension is disposed on the second end face onto which the fourth extension is extended.
In this arrangement, each width of the second extension and the fourth extension is longer than that of the first extension and the third extension, and is not shorter than {fraction (1/9)} of each width of the first internal electrode and the second internal electrode.
Preferably, each width of the second extension and the fourth extension is not shorter than ⅕ of each width of the first internal electrode and the second internal electrode.
In addition, preferably, at least one of the first extension and the third extension includes a plurality of extensions; at least one of the first external terminal electrode and the third external terminal electrode is disposed at multiple locations on at least one of the first side and the second side to be connected to each corresponding one of the extensions; and the first external terminal electrode and the third external terminal electrode are alternately positioned thereon.
Furthermore, preferably, at least one of the first extension and the third extension includes extensions which are extended onto both the first side and the second side; and at least one of the first external terminal electrode and the third external terminal electrode is disposed on both the first side and the second side so as to be connected to each corresponding one of the extensions.
Moreover, when the capacitor itself is seen in a certain direction in the order of the first end face, the first side, the second end face, and the second side, it is preferable that the first or second external terminal electrode which is connected to the first or second extension formed on the first internal electrode and the third or fourth external terminal electrode which is connected to the third or fourth extension formed on the second internal electrode be alternately positioned.
Moreover, preferably, the first internal electrode is opposing the second internal electrode at a plurality of locations so as to form a plurality of capacitor units, which are mutually connected in parallel by the first through fourth external terminal electrodes.
REFERENCES:
patent: 4831494 (1989-05-01), Arnold et al.
patent: 5815367 (1998-09-01), Asakura et al.
patent: 5822174 (1998-10-01), Yamate et al.
patent: 6038121 (2000-03-01), Naito et al.
patent: 2256216 (1990-10-01), None
Kondo Takanori
Kuroda Yoichi
Naito Yasuyuki
Taniguchi Masaaki
Kincaid Kristine
Murata Manfacturing Co., Ltd.
Ostrolenk Faber Gerb & Soffen, LLP
Thomas Eric
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