Plastic and nonmetallic article shaping or treating: processes – Outside of mold sintering or vitrifying of shaped inorganic... – Of magnetic article or component
Reexamination Certificate
1999-12-02
2001-04-17
Fiorilla, Christopher A. (Department: 1731)
Plastic and nonmetallic article shaping or treating: processes
Outside of mold sintering or vitrifying of shaped inorganic...
Of magnetic article or component
C264S612000, C264S613000
Reexamination Certificate
active
06217820
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of manufacturing a ferrite sintered body, and in particular relates to a method of manufacturing a ferrite sintered body which is suitable for use as an inductor such as a laminated chip inductor.
2. Description of the Related Art
Conventionally, various kinds of ferrite have been used as materials for manufacturing inductors such as a magnetic core material and a laminated chip inductor.
In the case of a laminated chip inductor, generally, ferrite layers and electrically conductive material patterns are laminated successively, a coil consisting of the electrically conductive material patterns laminated and combined together are formed between the ferrite layers so as to obtain a laminated body. Then, the laminated body is sintered so as to be formed into a sintered body. Further, external terminals are formed on the sintered body in a manner such that they are connected to the electrically conductive material patterns, thereby producing the desired product. In general, as a ferrite material for forming the laminated chip inductor, there have been in use a series of Ni—Cu—Zn ferrite materials and a series of Ni—Zn ferrite materials. As an electrically conductive material, Ag has been in practical use since it has a large electric conductivity.
With the development of a trend in which electronic devices are made compact in size but have improved performances and increased functions, there has been a demand that the ferrite parts for use in forming the electronic devices should also be made compact in size and be made to have further improved performance.
In order to meet the above requirements, a commonly used method in a case of an inductor material for use in forming a laminated chip inductor, for example, is for a glass to be added to the ferrite raw material, and various experiments have been conducted in order to improve various performances. However, the situation is still that it is difficult to sufficiently improve some ferrite properties such as &mgr;i (initial magnetic permeability) and Q (inverse of dielectric loss tan &dgr;).
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a method of producing a ferrite sintered body having a high &mgr;i and a high Q, suitable for use as a kind of inductor such as a laminated chip inductor.
In order to achieve the above object, a method of manufacturing a ferrite sintered body according to the present invention is characterized in that B
4
C is added in a ferrite raw material, followed by a firing treatment.
Further, the method is characterized in that the B
4
C is added in the ferrite raw material, and Mn or a Mn compound is further added into the ferrite raw material, followed by a firing treatment.
Moreover, the method is characterized in that the B
4
C is added in the ferrite raw material in an amount of about 10 to 3000 weight ppm.
Further, the method is characterized in that the amount of Mn or Mn compound added in the ferrite raw material is about 100 to 5000 weight ppm calculated as Mn
2
O
3
.
Moreover, the method is characterized in that the ferrite raw material contains at least two elements selected from the group consisting of Ni, Cu and Zn.
Further, the method is characterized in that the ferrite raw material has a composition in which Fe
2
O
3
is about 45.0 to 50.0 mol %, ZnO is 0 to about 50.0 mol %, and CuO is 0 to about 20.0 mol %, with the balance being NiO.
In addition, the method is characterized in that the ferrite sintered body is for use as an inductor.
As may be understood from the above description, by adding B
4
C in the ferrite raw material followed by a firing treatment, it is possible to obtain a ferrite sintered body having a high &mgr;i and a high Q.
In particular, using Ni—Cu—Zn ferrite and firing at a temperature of 870° C., it is possible to obtain a ferrite sintered body suitable for use as an inductor whose &mgr;i is 450 or more and whose Q is 80 or more.
Further, by adding either Mn or Mn compound in addition to the above B
4
C in the ferrite raw material, a ferrite sintered body suitable for use as a kind of inductor such as a kind of laminated chip inductor is obtained which has further higher &mgr;i and Q, a high volume resistivity and is capable of preventing a deterioration of insulating resistance which is possibly caused due to a migration of internal electrodes.
For the purpose of illustrating the invention, there is shown in the drawings several forms which are presently preferred, it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.
REFERENCES:
patent: 5770534 (1998-06-01), Hong
patent: 6113843 (2000-09-01), Aoki et al.
Ajichi Hideo
Kodama Takashi
Konoike Takehiro
Kurobe Junji
Nakamura Akihiro
Fiorilla Christopher A.
Murata Manufacturing Co. Ltd.
Ostrolenk Faber Gerb & Soffen, LLP
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