Compositions – Magnetic – Iron-oxygen compound containing
Reexamination Certificate
1998-12-23
2001-04-03
Koslow, C. Melissa (Department: 1755)
Compositions
Magnetic
Iron-oxygen compound containing
C252S062590, C252S062610, C252S062620, C310S155000, C336S234000
Reexamination Certificate
active
06210596
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic ceramic composition and to inductor elements using the composition.
2. Description of the Related Art
A magnetic ceramic composition typically contains ferrite as a primary component. Japanese patent Application Laid-Open (kokai) No. 1-110708, for example, discloses a magnetic ceramic composition containing ferrite and borosilicate glass. This publication also discloses inductors, such as chip inductors and LC complex elements, which make use of the magnetic ceramic composition as a magnetic substance. These inductors are constituted by laminated elements containing inner conductors.
According to the above publication, a magnetic ceramic composition containing ferrite and borosilicate glass provides chip inductors and ferrite-sintered bodies which have enhanced mechanical strength, can be sintered at a low temperature and are endowed with high frequency characteristics. Also, the above publication indicates that when LC complex elements are to be obtained, the above composition does not cause warping or separation even when the composition is co-sintered with an inductive material.
However, use of the above-mentioned composition containing ferrite and borosilicate glass tends to allow migration of inner conductors, which leads to the problems of insulation deterioration in the resultant inductor elements and an increase in direct current resistance.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a magnetic ceramic composition and inductor elements using the composition which resolve the above-mentioned problems.
In one aspect of the present invention, there is provided a magnetic ceramic composition containing ferrite serving as a primary component, and a sintering aid. The composition is characterized in that the sintering aid contains no boron, so as to solve the aforementioned technical problems.
In the composition of the present invention, the sintering aid preferably has the following composition: about 2-45 mol % Li
2
O, about 5-40 mol % RO (wherein R is at least one of Ba, Sr, Ca, and Mg), and about 30-70 mol % (Ti, Si)O
2
(wherein SiO
2
accounts for at least 15 mol %).
Preferably, the sintering aid content of the magnetic ceramic composition of the present invention is about 0.05-30 parts by weight with respect to 100 parts by weight of ferrite.
In one specific embodiment of the present invention, at least a fraction of the sintering aid comprises silicate glass.
Also preferably, the magnetic ceramic composition of the present invention further contains about 0.01-10 parts by weight of Bi
2
O
3
with respect to 100 parts by weight of ferrite.
In the cases described above, i.e., in cases in which the composition contains Bi
2
O
3
and at least some fraction of the sintering aid is silicate glass, a portion of Bi
2
O
3
may be present as a component of the silicate glass.
In the magnetic ceramic composition of the present invention, the ferrite is preferably a Ni-based ferrite, Ni-Zn-based ferrite or Ni-Cu-Zn-based ferrite.
In another aspect of the present invention, there is provided an inductor element in which the above-described magnetic ceramic composition is used as a magnetic substance.
Particularly, the present invention is advantageously applied to an inductor element in the form of a laminated element which contains an inner conductor.
REFERENCES:
patent: 4238342 (1980-12-01), Im et al.
patent: 4357251 (1982-11-01), Johnson, Jr. et al.
patent: 2712257 (1978-09-01), None
patent: 1110708 (1989-04-01), None
patent: 2-009767 (1990-01-01), None
Takaoka Tatsuru
Takenaka Kazuhiko
Koslow C. Melissa
Murata Manufacturing Co. Ltd.
Ostrolenk Faber Gerb & Soffen, LLP
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