Active solid-state devices (e.g. – transistors – solid-state diode – Combined with electrical contact or lead – Of specified material other than unalloyed aluminum
Reexamination Certificate
2001-05-14
2002-12-10
Nelms, David (Department: 2818)
Active solid-state devices (e.g., transistors, solid-state diode
Combined with electrical contact or lead
Of specified material other than unalloyed aluminum
C257S781000
Reexamination Certificate
active
06492733
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to laminated electronic components, and specifically a laminated electronic component comprising a composite obtained by integrally sintering a plurality of laminated magnetic layers in which a plurality of inductance elements, or an inductance element and a capacitance element are constituted in the interior of the composite.
2. Description of the Related Art
Various ferrite materials have been used as various magnetic core materials or materials for constituting laminated electronic components such as monolithic inductors owing to excellent electrophotographic characteristics.
In particular, in laminated electronic components such as monolithic inductors, silver or a material primarily composed of silver is used as a material for internal conductors; hence, magnetic layers constituting composites provided in the laminated electronic components must be simultaneously sinterable with Ag contained in the internal conductors. Thus, Ni—Cu—Zn-based ferrite materials, which can be sintered at a temperature below the melting point (960° C.) of Ag, are generally used as ferrite materials constituting the magnetic layers.
In a laminated electronic component, such as a monolithic inductor, obtained by simultaneously sintering a plurality of laminated magnetic layers composed of a Ni—Cu—Zn-based ferrite material and internal conductors containing Ag, the internal conductors are covered by the magnetic layers, generating no leakage magnetic flux and suppressing crosstalk. Thus, this has advantages, such as applicability to high-density packaging and high robustness, and is used in various fields.
In recent years, with reduction in size and weight, higher performance, and functional versatility of various electronic devices, reduction in size and weight and higher performance are highly required for electronic components used in these electronic devices, and high reliability are also required for ensuring the performance.
Regarding reliability, it is important that various electronic devices maintain the properties at, for example, high temperature and high humidity, supposing the use in various environments.
When a conventional ferrite material is, however, used in laminated electronic components having structures which generate potential differences, such as a laminated electronic component constituting a plurality of inductance elements or an inductance element and a capacitance element, migration of the internal conductor readily occurs and insulating resistance readily decreases in use under severe environments such as high temperature and high humidity, as described above.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a laminated electronic component which can solve the above-mentioned problems.
The present invention is directed to a laminated electronic component comprising a composite obtained by integrally sintering a plurality of laminated magnetic layers, an internal conductor being formed in the interior of the composite, the internal conductor and the magnetic layers constituting, at least one electrical element, such as an inductor or a capacitor, or a plurality of electrical elements, such as a plurality of inductance elements, or an inductance element and a capacitance element. In order to solve the above-mentioned technical problems, briefly speaking, it is characterized in that a specific amount of Mn compound is contained in a Ni—Cu—Zn ferrite which is the primary component in the composition of the magnetic layer.
In particular, the magnetic layers are characterized by having a primary component comprising 45 to 50 mole percent Fe
2
O
3
, 0 to 33 mole percent ZnO, and 6 to 20 mole percent CuO, and the balance being NiO, and a Mn compound wherein the Mn compound is contained in an amount of 0.01 to 2.0 weight percent as MnO in the composition.
The present invention is particularly advantageously applicable when the internal conductors contain Ag.
The laminated electronic component in accordance with the present invention can have various specific structures. For example, in the laminated electronic component, the internal conductor is provided with a plurality of internal conductors and a plurality of external terminal electrodes, each is electrically connected to each end of each of the plurality of internal conductors on outer surfaces of the composite. Alternatively, the internal conductor is provided with an internal conductor and at least one pair of opposing capacitor electrodes.
According to the present invention, as described above, a Mn compound is contained in an amount of 0.01 to 2.0 weight percent as MnO in the composition of the magnetic layer; hence, migration barely occurs when Ag is used in internal conductors, a superior sintered state is achieved at a firing temperature which enables simultaneous sintering with the Ag-containing internal conductors, and a monolithic electronic composite having superior reliability at high temperature and high humidity is thereby obtainable.
Accordingly, the present invention can be applied to monolithic electronic components provided with a plurality of inductance elements, for example, a monolithic electronic component in which an internal conductor is provided with a plurality of inductance conductors and a plurality of external terminal electrodes electrically connected to both ends of each of the plurality of inductance conductors, or monolithic electronic components provided with inductance elements and capacitance elements, for example, a monolithic electronic component in which an internal conductor is provided with an inductance conductor and at least one pair of opposing capacitor 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.
Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings.
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Kodama Takashi
Konoike Takehiro
Nakamura Akihiro
Tomono Kunisaburo
Murata Manufacturing Co. Ltd.
Nguyen Thinh
Ostrolenk Faber Gerb & Soffen, LLP
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