JP2004165440A - Inductance element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a DC superposition characteristics while a magnetic saturation is hard to occur. <P>SOLUTION: An inductor body comprises a magnetic layer in which a plurality of ferrite sheets 1-1 to 1-n are laminated, and a conductor layer in which, being laminated in one layer within the magnetic layer, a conductor pattern 2 is printed linearly as one streak on the ferrite sheet 1-i. An end face is provided with an external electrode 4 connected to the conductor pattern 2. A non-magnetic ceramic layer 5 that covers such ferrite sheet surface as no conductor pattern 2 is provided is provided to adjoin at least one side of the conductor pattern 2. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an inductance element formed by laminating a plurality of magnetic sheets, and more particularly to an inductance element used in a power supply unit of a computer and capable of flowing a large current at a high frequency.
[0002]
[Prior art]
FIG. 6 shows a circuit example of a multi-phase (three-phase) DC / DC converter. 101 is a control IC, VB is a power supply source, 102-1 to 102-3 are switching circuits, 103 is a load such as a CPU, and 106-1 to 106-3 are capacitors.
[0003]
Since the switching circuits 102-1 to 102-3 have the same configuration, the switching circuit 102-1 will be described. The switching circuit 102-1 includes switching elements 105-1a and 105-1b connected to a driving output terminal of the control IC 101, and an inductance element 104-1.
[0004]
In the above configuration, a load current ranging from several amps to several tens of amps flows through the load 103, and at the same time, a large current also flows through the inductance elements 104-1 to 104-3.
[0005]
By the way, in the related art, the operation (switching) frequency of the control IC 101 and the switching elements 105-1a to 105-3a and 105-1b to 105-3b used in the above circuit is not so high. As the inductance elements 104-1 to 104-3 used for 1 to 102-3, those having an inductance value of about several tens of μH (microhenry) were generally used.
[0006]
In recent years, with the advance of technology, the operating frequencies of the control IC 101 and the switching elements 105-1a to 105-3a and 105-1b to 105-3b have been dramatically increased. As an inductance element used in a DC converter circuit, an inductance element having an inductance value of 1 μH or less has come to be required.
[0007]
In addition, the performance of the CPU 103 has been improved along with the control IC 101 and the switching elements 105-1 a to 105-3 a and 105-1 b to 105-3 b, and the CPU 103 has been viewed as a load of the DC / DC converter circuit. In this case, the load current becomes very large.
[0008]
[Problems to be solved by the invention]
In order to cope with the above-mentioned current situation, inductance elements described in JP-A-10-27712 and JP-A-10-12443 are known as inductance elements corresponding to a large current. In these documents, non-magnetic ceramics are buried in a magnetic layer near the coil to reduce magnetic permeability near the coil, thereby suppressing magnetic saturation and improving DC bias characteristics.
[0009]
[Patent Document 1]
JP-A-10-27712 [Patent Document 2]
JP-A-10-12443
As shown in FIGS. 8 and 9, which are sectional views taken along line II of the perspective view shown in FIG. 7, the conventional multilayered inductance element has a conductor pattern 50 covered with a magnetic layer 51. The magnetic flux 54 passes through a space between the magnetic ceramics 52 and the like. For this reason, magnetic saturation could not be suppressed efficiently, and it was difficult to improve the DC bias characteristics.
[0011]
SUMMARY OF THE INVENTION An object of the present invention is to provide an inductance element in which magnetic saturation is less likely to occur than in the conventional example described above, and which can improve DC superimposition characteristics.
[0012]
[Means for Solving the Problems]
The inductance element according to the present invention forms an inductor body by a magnetic layer in which a plurality of ferrite sheets are laminated, and a conductor layer which is laminated on one of the magnetic layers and has a conductor pattern linearly printed on the ferrite sheet. In an inductance element provided with external electrodes connected to the conductor layer on a pair of end faces of the inductor body, a ferrite sheet surface on which the conductor pattern is not provided is adjacent to at least one side of the conductor pattern. It is characterized in that a nonmagnetic ceramic layer to cover is provided.
[0013]
The inductance element according to the present invention is characterized in that a nonmagnetic ceramic layer is provided on one side of a ferrite sheet surface on which the conductor pattern is not provided, and a ferrite layer is provided on the other side, with the conductor pattern not provided. And
[0014]
An inductance element according to the present invention includes a ferrite sheet provided with a nonmagnetic ceramic layer on one side of a ferrite sheet surface on which the conductor pattern is not provided, and a ferrite layer on the other side. It is characterized in that a plurality of sheets are laminated.
[0015]
The inductance element according to the present invention forms an inductor main body by a magnetic layer in which a plurality of ferrite sheets are stacked, and a conductor layer which is stacked on one layer in the magnetic layer, and in which a conductor pattern is linearly and double-printed on the ferrite sheet. In an inductance element in which external electrodes connected to the conductor layer are provided on a pair of end surfaces of the inductor body, a ferrite layer is provided in a region sandwiched by the two conductor patterns, and the remaining conductor pattern is not provided. A non-magnetic ceramic layer covering the ferrite sheet surface is provided.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an inductance element according to the present invention will be described with reference to the accompanying drawings. In the respective drawings, the same components are denoted by the same reference numerals, and redundant description will be omitted. In the inductance element of the present invention, as shown in FIG. 1A, a plurality of ferrite sheets 1-1 to 1-n are stacked to form a magnetic layer. At the center of the ferrite sheet 1-i laminated on one layer in the magnetic layer, a conductor layer in which the conductor pattern 2 is linearly printed in a single line is provided to form the inductor body 3.
[0017]
The conductive pattern 2 is made of Ag paste and has a width of 2.5 mm and a thickness of 100 μm or a width of 1.5 mm and a thickness of 150 μm. A non-magnetic ceramic layer 5 is provided adjacent to at least one side of the conductor pattern 2 to cover the surface of the ferrite sheet 1-i on which the conductor pattern 2 is not provided. Here, the nonmagnetic ceramic layer 5 is formed by applying a ceramic paste of an alumina-based glass ceramic to one side of the surface of the ferrite sheet 1-i where the conductor pattern 2 is not provided, with the conductor pattern 2 interposed therebetween. The ferrite layer 6 is provided on the other side by applying a ferrite paste of Ni-Cu-Zn ferrite. The thicknesses of the conductor pattern 2, the nonmagnetic ceramic layer 5, and the ferrite layer 6 are the same.
[0018]
As shown in FIG. 1A, the respective sheets are laminated and fired at a temperature lower than the melting point of Ag so that Ag as the conductor pattern 2 is not melted to obtain the inductor body 3.
[0019]
The inductor body 3 has a rectangular parallelepiped shape as shown in FIG. External electrodes 4, 4 are provided on a pair of end faces of the inductor body 3 by coating or the like so as to be connected to the conductor pattern 2. In the above description, the ferrite sheets 1-1 to 1-n are Ni-Cu-Zn ferrites, each having a thickness of about 80 μm, and 5.7 mm (length) × 5.0 mm (width) obtained by laminating 30 sheets. An inductor body 3 of 2.0 mm (height) is obtained.
[0020]
FIG. 2 is a cross-sectional view of the inductance element according to the first embodiment taken along line AA of FIG. 1B. A conductor pattern 2 is provided at the center of the ferrite sheet layer denoted by reference numeral 1, a nonmagnetic ceramic layer 5 is provided on one side of the conductor pattern 2, and a ferrite layer 6 is provided on the other side. Is provided.
[0021]
In the inductance element according to the first embodiment, as shown in FIG. 3, the magnetic flux 54 is hardly passed by the nonmagnetic ceramic layer 5. For this reason, magnetic saturation can be suppressed efficiently, and the DC bias characteristics can be improved.
[0022]
According to this configuration, a structure that is stronger than the case where the air gap is provided can be obtained. In the case where an air gap is provided, an operation of forming an air gap after lamination of the sheets is required. However, in the inductance element according to the first embodiment, the nonmagnetic ceramic layer 5 is formed in the lamination step of the sheets. Since it can be formed, the production becomes extremely easy.
[0023]
In the above embodiment, the nonmagnetic ceramic layer 5 is provided on one side of the surface of the ferrite sheet 1-i where the conductor pattern 2 is not provided, and the ferrite layer 6 is provided on the other side. Although one provided ferrite sheet 1-i is laminated, a plurality of such sheets may be laminated.
[0024]
In the inductance element according to the second embodiment of the present invention, as shown in FIG. 4A, a magnetic layer is formed by stacking a plurality of ferrite sheets 1-1 to 1-n. A conductor layer on which two conductor patterns 2A and 2B are printed in a straight line with a conductor pattern 2 is provided at the center of a ferrite sheet 1-k laminated on one layer in the magnetic layer to form an inductor body 3A.
[0025]
A ferrite layer 6A is provided by applying a ferrite paste of Ni-Cu-Zn ferrite to a region sandwiched between the two conductor patterns 2A and 2B. Nonmagnetic ceramic layers 5A and 5B are provided by applying a ceramic paste of alumina-based glass ceramic to the surface of the remaining ferrite sheet 1-k where the conductor pattern 2 is not provided.
[0026]
The inductor body 3 has a rectangular parallelepiped shape as shown in FIG. FIG. 5 is a sectional view taken along line BB of FIG. 4B in the inductance element according to the second embodiment. That is, the nonmagnetic ceramic layer 5A, the conductor pattern 2A, the ferrite layer 6A, the conductor pattern 2B, and the nonmagnetic ceramic layer 5B are arranged on the surface of the ferrite sheet 1-k at the center of the cross section from the left. Other configurations are the same as those of the first embodiment.
[0027]
Also according to the inductance element according to the second embodiment, since the magnetic flux hardly passes through the non-magnetic ceramic layers 5A and 5B according to the principle described with reference to FIG. The characteristics are improved.
[0028]
In the above, one ferrite sheet 1-k on which two conductor patterns are formed is laminated, but a plurality of such sheets may be laminated. Further, a configuration having three or more conductor patterns may be adopted. In this case, a nonmagnetic ceramic layer is provided adjacent to the side of the end face side of the conductor pattern located on the end face side.
[0029]
【The invention's effect】
As described above, according to the present invention, the nonmagnetic ceramic layer is provided adjacent to the side of the conductor pattern so that the magnetic flux hardly passes, so that the magnetic saturation can be suppressed efficiently and the DC superimposition characteristics can be improved. There is an effect that it can be achieved.
[Brief description of the drawings]
FIG. 1 is an assembled perspective view showing a first embodiment of an inductance element according to the present invention.
FIG. 2 is a sectional view taken along line AA of FIG. 1 (b).
FIG. 3 is a sectional view of a main part showing characteristics of the inductance element according to the present invention.
FIG. 4 is an assembled perspective view showing a first embodiment of the inductance element according to the present invention.
FIG. 5 is a sectional view taken along line BB of FIG. 4 (b).
FIG. 6 is a diagram illustrating a circuit example of a multi-phase (three-phase) DC / DC converter to which the inductance element according to the present invention is applied;
FIG. 7 is a perspective view of a conventional inductance element.
FIG. 8 is a sectional view taken along the line II of FIG. 7;
FIG. 9 is a cross-sectional view of a main part showing characteristics of an inductance element according to a conventional example.
[Explanation of symbols]
1, 1-1 to 1-n Ferrite sheet 1-i, 1-k Ferrite sheet 2 Conductor pattern 3, 3A Inductor 4 Electrode 5, 5A, 5B Nonmagnetic ceramic layer 6, 6A Ferrite layer

Claims (4)

A magnetic layer in which a plurality of ferrite sheets are laminated, and a conductor layer laminated on one layer in the magnetic layer and having a conductor pattern linearly printed on the ferrite sheet in a straight line, form an inductor body, and a pair of end faces of the inductor body. In an inductance element provided with an external electrode connected to the conductor layer,
An inductance element, comprising: a nonmagnetic ceramic layer that covers a ferrite sheet surface on which the conductor pattern is not provided, adjacent to at least one side of the conductor pattern. The non-magnetic ceramic layer is provided on one side of the ferrite sheet surface on which the conductor pattern is not provided, and the ferrite layer is provided on the other side with the conductor pattern interposed therebetween. Inductance element. A non-magnetic ceramic layer is provided on one side of the ferrite sheet surface where the conductor pattern is not provided, and a plurality of ferrite sheets provided with a ferrite layer are laminated on the other side, with the conductor pattern interposed therebetween. The inductance element according to claim 1. A magnetic layer in which a plurality of ferrite sheets are laminated, and a conductor layer laminated on one layer in the magnetic layer and having a conductor pattern linearly and double-printed on the ferrite sheet to form an inductor body, a pair of end faces of the inductor body In an inductance element provided with an external electrode connected to the conductor layer,
A ferrite layer is provided in an area sandwiched by the two conductor patterns,
An inductance element comprising a nonmagnetic ceramic layer covering the remaining ferrite sheet surface on which the conductor pattern is not provided.

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