The present invention relates to laminated inductors including magnetic layers and conductive patterns alternately laminated, and, more particularly, to a laminated inductor including mixed layers having a magnetic portion and a nonmagnetic portion.
Many inductance elements, each obtained by winding a coil conductor around a magnetic core, have been generally used in circuits of electronic components. In recent years, a laminated inductor is often used instead of such an inductance element to meet a miniaturization demand.
In general, in a laminated inductor, magnetic layers and conductive patterns are alternately laminated and the conductive patterns are electrically connected to one another such that that conductive patterns function as a coil conductor. However, when a direct current is applied to such a laminated inductor, an inductance value rapidly reduces as a result of an occurrence of magnetic saturation at magnetic substances in accordance with the increase in current. That is, DC superposition characteristics deteriorate.
Japanese Unexamined Patent Application Publication No. 2006-318946 (Patent Document 1) discloses a laminated inductor including a magnetic gap portion obtained by replacing a part of a magnetic layer with a nonmagnetic substance. Using the configuration of a laminated inductor disclosed in Patent Document 1, it is possible to suppress magnetic saturation at the time of application of a direct current to the laminated inductor and improve DC superposition characteristics.
The present disclosure provides a laminated inductor capable of obtaining more sufficient and excellent DC superposition characteristics and suppressing external magnetic leakage.
In an embodiment of a laminated inductor according to the disclosure, magnetic layers and conductive patterns are alternately laminated, and the conductive patterns are electrically connected to one another and function as a coil conductor. The laminated inductor includes a plurality of first mixed layers each obtained by forming a first portion between ones of the conductive patterns overlapping in a lamination direction and a second portion that is inside the coil conductor and is connected to the first portion with a nonmagnetic material and a plurality of second mixed layers each obtained by forming the first portion between ones of the conductive patterns overlapping in the lamination direction and a third portion that is outside the coil conductor and is connected to the first portion with the nonmagnetic material. The plurality of first mixed layers and the plurality of second mixed layers are formed as different layers.
In another embodiment of a laminated inductor according to the disclosure, magnetic layers and conductive patterns are alternately laminated and the conductive patterns are electrically connected to one another and function as a coil conductor. The laminated inductor includes plural first mixed layers and plural second mixed layers. Each first mixed layer includes a nonmagnetic material portion inside the coil conductor. Each second mixed layer each includes a nonmagnetic material portion outside the coil conductor. The plural first mixed layers and the plural second mixed layers are formed as different layers.
In a more specific embodiment of a laminated inductor according to the disclosure, the plural first mixed layers may be positioned nearer to a center of the laminated coil conductor in the lamination direction than the plural second mixed layers.
In another more specific embodiment of a laminated inductor according to the disclosure, the plural first mixed layers and the plural second mixed layers may be positioned symmetrically with respect to a center of the laminated coil conductor in the lamination direction.
The inventors realized that in the laminated inductor disclosed in Patent Document 1, the magnetic gap portion made of a nonmagnetic substance is disposed only outside a coil conductor. Accordingly, it is effective to a certain extent for the improvement of DC superposition characteristics, but sufficient DC superposition characteristics cannot be obtained. In addition, the amount of external magnetic leakage in the laminated inductor disclosed in Patent Document 1 is increased because many magnetic gaps are formed outside the coil conductor.
Exemplary embodiments of the present disclosure that can address these shortcomings will now be described with reference to the accompanying drawings. In the drawings, the same reference numeral is used to represent the same component or the same part so as to avoid repeated explanation.
In the following exemplary embodiments, a conductive material having silver or a silver alloy as a major component is used to form a conductive pattern, a magnetic material made of Ni—Cu—Zn ferrite is used to form a magnetic layer, and a nonmagnetic material made of Cu—Zn ferrite is used to form first and second mixed layers. It is to be noted, however, that the above-described materials are for illustrative purposes only.
The first mixed layer 3 is obtained by replacing a part of a magnetic material with a nonmagnetic material. More specifically, as illustrated in
The second mixed layer 4 is obtained by replacing a part of a magnetic material with a nonmagnetic material. More specifically, as illustrated in
The first mixed layer 3 and the second mixed layer 4 are formed as different layers, that is, are in different levels.
By configuring the laminated inductor 10 as described previously, it is possible to suppress concentration of magnetic gap portions and prevent local magnetic saturation. Accordingly, excellent DC superposition characteristics can be obtained. Furthermore, the amount of external magnetic leakage can be reduced.
Like in the first exemplary embodiment, in this embodiment, it is possible to suppress concentration of magnetic gap portions and prevent local magnetic saturation.
According to this embodiment, as compared with the first and second exemplary embodiments, it is possible to more effectively suppress concentration of magnetic gap portions and prevent local magnetic saturation.
In the fourth exemplary embodiment illustrated in
As is apparent from this graph, the amount of reduction in an inductance value with the increase in an applied direct current in the case of (c), (d), and (e) is lower than that in the case of (a) and (b). Therefore, according to embodiments consistent with the present disclosure, it is possible to suppress concentration of magnetic gap portions and prevent local magnetic saturation. As a result, excellent DC superposition characteristics can be obtained.
In embodiments according to the disclosure, a first mixed layer obtained by forming a portion inside a coil conductor with a nonmagnetic material and a second mixed layer obtained by forming a portion outside the coil conductor with the nonmagnetic material are laminated as different layers. Accordingly, as compared with a structure in which a nonmagnetic substance is formed only outside a coil conductor, the concentration of magnetic gap portions is suppressed and local magnetic saturation can be prevented. As a result, excellent DC superposition characteristics can be obtained. In addition, external magnetic leakage can be suppressed.
Embodiments according to the disclosure can be useful in applications that utilize a laminated inductor, and, in particular, can have an advantage in suitability for obtaining excellent DC superposition characteristics and suppressing external magnetic leakage.
It should be understood that the above-described embodiments are illustrative only and that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the disclosure. The scope of the invention should be determined in view of the appended claims and their equivalents.
Number | Date | Country | Kind |
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2009-012157 | Jan 2009 | JP | national |
The present application is a continuation of International Application No. PCT/JP2009/070975, filed Dec. 16, 2009, which claims priority to Japanese Patent Application No. 2009-012157 filed Jan. 22, 2009, the entire contents of each of these applications being incorporated herein by reference in their entirety
Number | Date | Country | |
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Parent | PCT/JP2009/070975 | Dec 2009 | US |
Child | 13188650 | US |