Inductor devices – Coil or coil turn supports or spacers – Printed circuit-type coil
Reexamination Certificate
1995-03-24
2001-07-03
Mai, Anh (Department: 2832)
Inductor devices
Coil or coil turn supports or spacers
Printed circuit-type coil
C336S083000, C336S232000
Reexamination Certificate
active
06255932
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electronic component having a built-in inductor which comprises a substrate and an inductance element provided therein, and more particularly, it relates to an electronic component having a built-in inductor which comprises an inductance element of a ferromagnetic metal.
2. Description of the Background Art Conventional electronic components comprising substrates and inductance elements provided therein are manufactured by the following methods (1) to (3):
(1) A method of providing an inductance element, which is prepared by forming a conductor in a ferrite member with conductor paste, in an unfired ceramic substrate and there-after simultaneously firing the substrate material and the conductor paste, thereby obtaining a substrate having a built-in inductance.
(2) A method of providing a ferrite layer, which is previously formed with a conductor consisting of conductor paste therein, in an unfired ceramic substrate and firing the unfired ceramic substrate with the ferrite layer and the conductor paste.
(3) A method of utilizing an inductance which is generated from a conductor provided in a substrate, without particularly employing a ferromagnetic substance.
Each of the methods (1) and (2) comprises the step of simultaneously firing the ceramic material forming the substrate and the ferrite material. Therefore, the ferrite and ceramic components are mutually diffused in the firing, to disadvantageously reduce electric characteristics. In particular, iron oxide which is contained in the ferrite material is quickly diffused to reduce insulation resistance upon diffusion in an insulating ceramics. Thus, it is necessary to suppress the reduction of insulation resistance caused by such diffusion of the iron oxide.
In the method (3) utilizing an inductance which is generated from a conductor provided in a substrate without employing a ferromagnetic substance, on the other hand, it is necessary to increase the length of the conductor part for forming the inductance, and hence the component size is inevitably increased.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an electronic component having a built-in inductor hardly causing reduction of electric characteristics such as insulation resistance, which can reduce the size of a portion forming an inductance element.
The present invention is directed to an electronic component having a built-in inductor comprising a substrate which consists of an insulating material, a conductor which is provided in the substrate, and at least one ferromagnetic metal film which is arranged in the substrate to be separated from but in proximity to the conductor.
In the electronic component having a built-in inductor according to the present invention, at least one ferromagnetic metal film is arranged in proximity to the conductor as described above, thereby forming an inductor. In this case, the ferromagnetic metal film may be arranged in the substrate to be flush with the conductor, or at least one ferromagnetic metal film may be formed in proximity to the conductor in a position opposite to the conductor surface through an insulating material layer forming the substrate. These two modes of arrangement may be combined with each other.
The inductor is formed by arranging the ferromagnetic metal film, which can be prepared from a proper ferromagnetic metal material. When the substrate is made of a ceramics material, the ferromagnetic metal film is preferably prepared from a material capable of withstanding firing of the ceramics material, such as a ferromagnetic metal film which is made of or mainly composed of Ni, for example.
While the feature of the electronic component having a built-in inductor according to the present invention resides in that the conductor and at least one ferromagnetic metal film are arranged in the substrate as described above, the substrate is not restricted to that made of ceramics, but may be made of another insulating material such as synthetic resin.
According to the present invention, at least one ferromagnetic metal film is arranged in the substrate in proximity to the conductor, to form the inductor. Namely, the inductance element is formed by arranging the ferromagnetic metal film in proximity to the conductor, whereby no ferrite member is required as a magnetic material. Therefore, the electronic component having a built-in inductor can be formed by a single substrate material, and hence no problem such as reduction of insulation resistance is caused by mutual diffusion of ceramics and ferrite when the substrate is made of ceramics, for example. Thus, it is possible to provide an electronic component having a built-in inductor which has excellent electric characteristics and reliability.
When the length of the conductor provided in the substrate of the conventional electronic component is increased for forming an induction element, the size of the inductance forming part is disadvantageously increased. According to the present invention, on the other hand, the inductor is formed by arranging the aforementioned ferromagnetic metal film, whereby it is possible to miniaturize the electronic component having a built-in inductor with no dimensional increase of the inductance element forming part.
When the ferromagnetic metal film is formed by a thin film forming method and patterned by photolithography, further, the ferromagnetic metal film can be formed in high accuracy, whereby an inductance can be accurately implemented at the designed value.
While the method of arranging the ferromagnetic metal film can be varied as described above, it is possible to implement a higher inductance when the ferromagnetic metal film is arranged in the substrate not only to be flush with the conductor but in proximity to the conductor in a position opposed to the conductor surface.
When the ferromagnetic metal film is formed by a metal film which is made of or mainly composed of Ni, further, the ferromagnetic metal film is hardly oxidized in firing even if the substrate is made of ceramics.
REFERENCES:
patent: 3731005 (1973-05-01), Shearman
patent: 4117588 (1978-10-01), Johnson
patent: 4959631 (1990-09-01), Hasagawa et al.
patent: 5349743 (1994-09-01), Grader et al.
patent: 2163603 (1986-02-01), None
patent: 44-14264 (1965-08-01), None
patent: 62-104112 (1987-05-01), None
patent: 6-151185 (1994-05-01), None
IBM Technical Disclosure Bulletin, “Etched Transvormer”, Crawford et al, vol. 8. No. 5, Oct. 5, 1965 p. 723, copy in 336-200.
Kohno Yoshiaki
Kubodera Noriyuki
Mai Anh
Murata Manufacturing Co. Ltd.
Ostrolenk Faber Gerb & Soffen, LLP
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