JP2003217941A - Inductance element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of reduction in conversion efficiency of an inductance element using a conventional metal magnetic powder, the reduction being caused by increased loss, when the inductance element is used for a DC/DC converter and so on, and the inductance element increasing a current resistance of a coil due to a low magnetic permeability of a magnetic substance. <P>SOLUTION: The inductance element comprises an insulating magnetic substance 20, which is formed by pressing metal magnetic powder and an adhesive agent, at least a single coil 10 having a winding part 11 and a core part 12, which are embedded in the magnetic substance 20, and a plurality of leads 13 and 14 drawn from the winding part 11, a winding core 30 wound by an amorphous magnetic foil band in a spiral manner, and a plurality of terminal electrodes 40 which conduct to the leads 13 and 14 of the coil and are exposed to the outside. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC / DC integrated in a portable electronic device such as a notebook computer and a video camera.
The present invention relates to a surface mount type inductance element suitable as a circuit element such as a DC converter.

[0002]

2. Description of the Related Art An inductor is used in which a coil is embedded inside a dust core obtained by pressure-molding a metal magnetic powder to which a binder is added. This inductor has a structure in which the terminal electrode is in direct contact with the dust core, so that the insulating property of the magnetic metal powder is required. For this reason, the surface of the particles of the magnetic metal powder is subjected to a chemical insulation treatment, further coated with a bonding agent, and then the magnetic metal powder is pressure-molded.

[0003]

If the thickness of the insulating coating of the particles of the metal magnetic powder is increased in order to secure high insulation, the effective magnetic permeability will be significantly reduced. In order to secure a certain inductance by using the magnetic material having the reduced magnetic permeability, it is necessary to increase the number of turns of the coil. As a result, the DC resistance of the coil increases and DC / DC
When used in a converter or the like, there is a problem that the loss increases and the conversion efficiency decreases. Therefore, an object of the present invention is to increase the effective magnetic permeability while ensuring the insulation between terminals, reduce the DC resistance even with a high inductance, and improve the conversion efficiency.

[0004]

The inductance element of the present invention comprises an insulating magnetic body formed by pressure-molding metal magnetic powder and a bonding agent, and a winding portion and a winding embedded in the magnetic body. At least one coil having a winding core portion surrounded by a wire portion and a plurality of lead portions derived from the winding portion, a winding core formed by winding an amorphous magnetic foil strip in a spiral shape, and conducting to the lead portion of the coil. A plurality of terminal electrodes exposed to the outside are provided, and the winding core is embedded in the magnetic body and arranged in the winding core.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention applied to a surface mount type inductor is shown in FIGS. The coil 10 has a cylindrical winding portion 11 in which a wire having a circular cross section is wound in multiple layers,
It has a winding core portion 12 surrounded by a winding portion 11 and lead portions 13 and 14 led out from both ends of the winding portion 11, respectively. Coil 10
Is embedded inside the magnetic body 20. Core of coil 10
A cylindrical winding core 30 in which a high magnetic permeability amorphous magnetic foil strip is spirally wound is attached to the coil 12. This volume core
30 is also embedded inside the magnetic body 20.

The pair of terminal electrodes 40, which are partially embedded in the magnetic body 20 and fixed, have the remaining portions exposed to the outside extending along the surface of the magnetic body 20 from the side surfaces to the bottom surface.
The lead portions 13 and 14 of the coil 10 are connected to different terminal electrodes 40 inside the magnetic body 20 by means such as welding.

The magnetic body 20 is made of metal magnetic powder such as iron or sendust or permalloy which is wrapped with a bonding agent made of a thermosetting resin or a thermoplastic resin.
140 ° C after pressure molding at a pressure of about 2 tons per
It is heated and cured at about the same temperature. The particles of the metal magnetic powder of the magnetic body 20 are subjected to an insulation treatment, and the magnetic body 20 is insulative. Carbonyl iron powder having a small average particle size is suitable for the magnetic body 20.

Since the amorphous magnetic material has an amorphous shape, it has a very high magnetic permeability, and the magnetic permeability of the winding core 30 formed of the amorphous magnetic foil strip is 100 times the magnetic permeability of the magnetic material 20. It becomes the above value. Therefore, the effective magnetic permeability of the entire inductor is significantly improved as compared with the case where only the insulating magnetic body 20 is used for the magnetic body portion.

FIG. 3 shows another embodiment of the present invention.
A coil 50 made of a rectangular wire is used instead of the round wire. The coil 50 includes a winding portion 51 in which a rectangular wire is edgewise wound, a winding core portion 52 surrounded by the winding portion 51, and lead portions 53 and 54 at both ends of the winding portion 51. Lead part 53, 54
Has a structure in which it is led out from the two side surfaces of the magnetic body 20 to serve as a terminal electrode as it is. The winding method of the rectangular wire is not limited to the edgewise winding, and may be a spiral shape.

As the coil, it is also possible to use a so-called outer-outer winding coil in which both ends are pulled out from the outermost circumference. FIG. 4 shows an example of the outer-outer winding coil, in which the wire is wound in opposite directions from the center of the wire.
It has a column structure. This coil 60 has a single rectangular wire continuously wound in two layers in upper and lower layers, and has lead portions at both ends.
63 and 64 are located on the outermost circumference.

When the coil is wound outside-outside, the lead portion at the beginning of winding does not overlap the winding portion, which is effective in reducing the thickness of the inductance element as a whole. The outer-outer winding coil may have a multi-stage structure of three or more stages, and may be formed by a round wire instead of the rectangular wire. Although the above embodiments have been described by taking the example of the inductor, the inductance element of the present invention may be configured as a transformer by providing a plurality of coils.

[0012]

According to the structure of the present invention in which the winding core having a high magnetic permeability is embedded in the winding core of the coil, the effective magnetic permeability of the entire inductance element can be increased while ensuring the insulation between the terminal electrodes. . As a result, the number of turns of the coil can be reduced and a thick and short wire can be used to reduce the DC resistance.
When used in a / DC converter or the like, it is possible to significantly reduce the loss.

[Brief description of drawings]

FIG. 1 is a front sectional view of an inductor showing a first embodiment of the present invention.

FIG. 2 is a perspective view of the inductor.

FIG. 3 is a front sectional view showing a second embodiment of the present invention.

FIG. 4 is a plan view showing another embodiment of the coil.

5 is a sectional view taken along line AA of FIG.

[Explanation of symbols]

10 coils 11 winding part 12 winding core 20 magnetic material 30-roll core

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01F 37/00 H01F 27/24 C (72) Inventor Michiya Nakazawa 18 Gomigaya, Tsurugashima City, Saitama Prefecture Toko Co., Ltd. Saitama Plant (72) Inventor, Victory, Chibahara 18 Gomigaya, Tsurugashima City, Saitama Prefecture Toko Co., Ltd. Saitama Plant F-term (reference) 5E043 AB02 EA01

Claims (5)

[Claims] 1. An insulating magnetic body formed by pressure-molding a metal magnetic powder and a bonding agent, a winding portion embedded in the inside of the magnetic body, a winding core portion surrounded by the winding portion, and a winding. At least one coil having a plurality of lead portions derived from the wire portion, a winding core formed by spirally winding an amorphous magnetic foil strip, and a plurality of terminal electrodes that are electrically connected to the lead portions of the coil and exposed to the outside An inductance element in which a winding core is embedded in a magnetic body and arranged in a winding core portion. 2. The inductance element according to claim 1, wherein the metallic magnetic powder is carbonyl iron powder. 3. The inductance element according to claim 1, wherein the coil is an outer-outer winding. 4. The inductance element according to claim 1, wherein the coil wire is a rectangular wire. 5. The inductance element according to claim 4, wherein a part of the lead portion of the coil also serves as the terminal electrode.