JP2002359125A - Inductor component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inductor component that can obtain the maximum bias effect by the minimum number of turns without requiring any need for securing clearance. SOLUTION: At the outer periphery of a band- or rod-like conductor 13, at least two cores 11 and 12 are combined for forming a closed magnetic circuit. At least at one place in the closed magnetic circuit, the cores are combined via a permanent magnet 14. In the conductor, both ends may be formed in plate shapes having widths being wider than a center section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inductor component having a magnet inserted into a gap of a magnetic core.
The present invention relates to an inductor component used for various electronic devices, switching power supplies, and the like.

[0002]

2. Description of the Related Art Conventionally, an inductor component used for a switching power supply or the like is constituted by inserting a permanent magnet 72 into a gap of an EE type magnetic core (magnetic core) 71 as shown in FIG. Here, the size 74 of the magnetic gap varies to some extent, and the thickness 75 of the permanent magnet 72 also varies to some extent due to the unevenness of the magnet surface.
Therefore, in order to prevent the permanent magnet 72 from entering the magnetic gap of the EE type magnetic core 71, the magnetic core 71
Sufficient clearance 76 is secured between the magnet and the permanent magnet 72.

[0003]

However, in the above-mentioned conventional inductor component, the clearance becomes a magnetic resistance, which is an obstacle for obtaining the maximum bias effect. That is, when a permanent magnet is inserted into the gap of the EE-type magnetic core, it is necessary to ensure sufficient clearance. Therefore, inserting a magnet thinner than the gap amount has a disadvantage that the bias effect is reduced. Increasing the bias amount by inserting a thick magnet increases the gap, lowers the inductance value, and necessitates increasing the number of turns. This is an obstacle to realizing a small size.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an inductor component which can obtain a maximum bias effect with a minimum number of turns and without requiring a clearance.

[0005]

The inductor component according to the present invention is characterized in that a closed magnetic circuit is formed by combining two or more cores around the outer periphery of a strip-shaped or rod-shaped conductor, and a permanent magnet is inserted into the joint of the cores. Since the thickness of the magnet becomes the gap amount, a magnet having a thickness equal to the gap amount can be inserted, and the maximum bias effect can be obtained. The increase in the magnetic flux density due to the bias effect can reduce the number of turns, thereby greatly contributing to a reduction in loss of the inductor component and a reduction in size and weight. It is desirable to reduce to the minimum number of turns.

In the inductor component of the present invention, the permanent magnet is made of at least one kind selected from a polyamideimide resin, a polyimide resin, an epoxy resin, a polyphenylene sulfide resin, a silicon resin, a polyester resin, an aromatic polyamide resin, and a liquid crystal polymer. Resin specific coercive force is 10KOe or more, Tc is 500 ° C or more, powder average particle size is 2.
5-25 μm and Zn, Al, Bi, Ga, In, Mg, Pb, Sb,
And rare earth magnet powder coated with at least one metal or an alloy thereof of Sn is dispersed, the resin content is 30% or more by volume, and the specific resistance is 0.1 Ωcm or more. . However, the rare earth magnet powder used for this permanent magnet has a composition of SmCo, and specifically, the composition Sm (Co
_bal. Fe _0.15-0.25 Cu _0.05-0.06 Zr _0.02-0.03 ) It is preferable that the particle size is _7.0-8.5 , and the maximum particle size is 50 μm or less.

Thus, the Curie temperature Tc is applied to the permanent magnet.
By using the SmCo-based magnet powder having a high intrinsic coercive force Hc, the initial characteristics can be maintained without loss of the coercive force Hc and demagnetization even when placed in a heating state in the reflow soldering process. . Also, by kneading the SmCo-based magnet powder with the resin at a volume ratio of 30% or more, it is possible to increase the specific resistance, and it is possible to greatly reduce the eddy current loss of the permanent magnet.

Further, in the inductor component of the present invention,
550 ° C at softening point of 220 ° C or higher for SmCo-based magnet powder
If coated with the following inorganic glass, or if the metal or alloy coated on the SmCo-based magnetic powder is coated with a nonmetallic inorganic compound having a melting point of at least 300 ° C. or more, oxidation over time progresses and demagnetization occurs. Can be prevented. It is preferable that the amount of the inorganic glass or the nonmetal compound added is in the range of 0.1 to 10% by volume. In addition, as an embodiment, SmC
If an o-based magnet powder is magnetically anisotropic by orienting in the thickness direction with a magnetic field, and a permanent magnet having a magnetization magnetic field of 2.5 T or more and a center line average roughness Ra of 10 μm or less is produced, It can be effectively applied in various fields as an inductor component.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an inductor component according to a first embodiment of the present invention will be described in detail with reference to FIGS. FIG. 1 is a diagram showing a configuration of an inductor component according to a first embodiment of the present invention,
(A) is an assembled perspective view, and (b) is a cross-sectional view of (a), showing directions of magnetic flux lines generated by a magnetic field generated by a current flowing through a conductor and a magnetic field generated by a permanent magnet.

The illustrated inductor component has a U-shaped core 11.
And an I-shaped core 12, a conductor 13, and a permanent magnet 14. As shown in FIG. 1B, the magnetic flux generated by the magnetic field due to the current flowing in the conductor 13 flows in the direction of the solid arrow (reference numeral 15), and the permanent magnet 14
The magnetic flux generated by the magnetic field due to the dashed arrow (reference numeral 16)
Flows in the direction of

The U-shaped core 11 and the I-shaped core 12 used herein are made of Mn-Zn ferrite and have a magnetic path length of 2.
0 cm and an effective area of 0.5 cm ² . The dimensions of the combined core are 20 mm × 10 mm × 5 mm. ^Two permanent magnets 14 each having a thickness of 50 μm and a cross-sectional area of 0.5 cm ² are used, and SmCo is used as a raw material powder. The specific contents will be described later in detail.

The conductor 13 is formed by stamping a copper plate into a predetermined shape and applying a solder plating. The DC resistance is 0.35 mΩ. The permanent magnets 14 are arranged at two places where the U-shaped core 11 and the I-shaped core 12 are in contact with each other. The direction of the permanent magnet 14 is the conductor 13
Is determined to generate a magnetic field in the opposite direction to the magnetic field generated by
The core is assembled and joined by tape or adhesive. FIG. 5 shows the result of the measurement of DC superposition.

In FIG. 5, a solid line 51 indicates a case where the permanent magnet 14 is inserted, and a solid line 52 indicates a case where the permanent magnet 14 is not inserted. As is apparent from the results, the permanent magnet 14 improved the DC superposition by about 35%.

Next, an inductor component according to a second embodiment of the present invention will be described in detail with reference to FIGS. FIGS. 2A and 2B are diagrams showing a configuration of an inductor component according to a second embodiment of the present invention, wherein FIG. 2A is a perspective view of the completed assembly, FIG. 2B is a sectional view of FIG. FIG. 4 is a diagram showing the directions of magnetic flux lines generated by a magnetic field generated by a current flowing through the magnetic field and a permanent magnet.

The illustrated inductor component has an L-shaped core 27.
And a permanent magnet 24 composed of a magnetic core composed of a magnetic core and an I-shaped core 22, and finally assembled as shown in FIG. As shown in FIG. 2B, the magnetic flux generated by the magnetic field due to the current flowing through the conductor 23 flows in the direction of the solid arrow (reference numeral 25), and the permanent magnet 24
The magnetic flux generated by the magnetic field due to the dashed arrow (reference numeral 26)
Flows in the direction of

The L-shaped core 27 and the I-shaped core 22 used here are made of Mn-Zn ferrite and have a magnetic path length of 2.
0 cm and an effective area of 0.5 cm ² . The dimensions of the combined core are 20 mm × 10 mm × 5 mm. The permanent magnet 24 has a thickness of 100 μm and a cross-sectional area of 0.5 cm ² , and has a single shape, and SmCo is used as a raw material powder.

The conductor 23 is formed by stamping a copper plate into a predetermined shape and performing solder plating. The DC resistance is 0.35 mΩ. The permanent magnet 24 is disposed only on one side where the L-shaped core 27 and the I-shaped core 22 are in contact, and the direction is determined so as to generate a magnetic field in a direction opposite to the magnetic field generated by the conductor 23. The core is assembled and joined by tape or adhesive. FIG. 6 shows the result of the measurement of DC superposition.

In FIG. 6, a solid line 61 indicates a case where the permanent magnet 24 is inserted, and a solid line 62 indicates a case where the permanent magnet 24 is not inserted. As is clear from the results, the DC bias was improved by about 35% by the permanent magnet 24.
When irreversible demagnetization by reflow soldering heat and demagnetization by oxidation are performed, a DC superimposition characteristic as shown by 63 in FIG. 6 is obtained.

Next, an inductor component according to a third embodiment of the present invention will be described in detail with reference to FIG.
FIGS. 3A and 3B are views showing the configuration of an inductor component according to a third embodiment of the present invention, wherein FIG. 3A is a perspective view of the completed assembly, and FIG. .

The illustrated inductor component has a U-shaped core 31.
And an I-shaped core 32, a conductor 33, and a permanent magnet 34. Both ends of the conductor 33 are wider and flatter than the central part thereof, and serve as terminals to be mounted on a substrate.
The wide portion of the conductor 33 restricts the movement of the core and facilitates the assembling work of the core, and the flat portion improves the mounting stability of the inductor component.

In any of the first to third embodiments, the magnetic core is a combination of U-shaped cores or a L-shaped core.
The present invention can be implemented in various forms in which an equi-closed magnetic path is formed by a combination of U-shaped cores or the like, and is not particularly limited to the above-described one. FIGS. 4A and 4B show some modified examples. In FIG. 4, 41 is a U-shaped core, 42
Is an I-shaped core, 43 is a conductor, and 44 is a permanent magnet.

The permanent magnet has a specific holding force of 10 KO.
e, a rare earth magnet powder having a Curie temperature Tc of 500 ° C. or more and a powder average particle size of 2.5 to 50 μm dispersed in a resin having a volume of 30% or more, and having a specific resistance of 0.1 Ω.
cm or more is preferred.

[0023] More preferably, the composition of the rare earth magnet powder _{is Sm (Co bal. Fe 0.10 -0.25} Cu
_0.05-0.06 Zr _0.02-0.03 )
_7.0-8.5 , and the type of resin used for the permanent magnet is polyamide-imide resin, epoxy resin, polyphenylsulfite resin, silicon resin, polyimide resin,
Aromatic nylon, and formed of any one or a composite of liquid crystal polymer, the surface of the rare earth magnet powder,
0.1-10% by volume ratio Zn, Al, Bi, Ga, I
One of n, Mg, Pb, Sb, and Sn, or an alloy is coated or a composite is formed. The magnet powder is subjected to a surface treatment with a dispersing material such as a silane coupling material or a titanium coupling material before being mixed with the resin.

In order to obtain higher characteristics, the permanent magnet is magnetically anisotropic by magnetic field orientation in the thickness direction when the permanent magnet is manufactured. By magnetizing, an excellent DC superimposition characteristic can be obtained, and a magnetic core without deterioration of the core loss characteristic can be formed.
This is because the magnet properties required to obtain excellent DC superimposition characteristics are not the energy products, but the intrinsic holding power,
Therefore, even if a permanent magnet having a high specific resistance is used, a sufficiently high DC superimposition characteristic can be obtained if the intrinsic coercive force is high. The permanent magnet desirably has a center line average roughness Ra of 10 μm or less.

Further, the softening point of the rare earth magnet powder is 220 ° C.
It is preferable to coat with an inorganic glass having a temperature of at least 550 ° C. In that case, the volume of the inorganic glass is set to 0.1 to 10% by volume.

The rare earth magnet powder may be coated with a metal or an alloy and then with a nonmetallic inorganic compound having a melting point of at least 300 ° C. In that case, the metal or alloy may be 0.1 to 10% by volume ratio, or the addition amount of the metal or alloy and the inorganic compound may be 0.1 to 10% by volume ratio.

Further, the magnetic core may be made of a silicon steel plate or amorphous.

Conventionally, a closed magnetic circuit is formed by combining two or more cores on the outer periphery of a strip-shaped or rod-shaped conductor, and a gap is secured by sandwiching an insulating sheet at the joint of the cores. In each of the inductor components, the bias is applied by replacing the insulating sheet with a permanent magnet. Therefore, there is no restriction that the clearance must be secured due to the dimensional variation of the center leg gap of the magnetic core and the dimensional variation of the permanent magnet.

[0029]

As described above, according to the present invention,
By securing the clearance due to the gap dimensional variation and the permanent magnet thickness variation, it is possible to provide an inductor component in which the bias effect does not decrease. As a result, it is possible to reduce the size and the loss of the inductor component.

[Brief description of the drawings]

1A and 1B show an inductor component according to a first embodiment of the present invention, wherein FIG. 1A is an overall perspective view, and FIG. 1B is a cross-sectional view of FIG.

2A and 2B show an inductor component according to a second embodiment of the present invention, wherein FIG. 2A is an overall perspective view, and FIG. 2B is a cross-sectional view of FIG.

3A and 3B show an inductor component according to a third embodiment of the present invention, wherein FIG. 3A is an overall perspective view, and FIG. 3B is a side view showing a state where the inductor component is mounted on a substrate.

FIG. 4 shows a modification of the inductor component of FIGS. 1 to 3,
(A) is a sectional view of one example, and (b) is a sectional view of another example.

FIG. 5 is a graph showing a measurement result of DC superposition in the inductor component of FIG. 1;

FIG. 6 is a graph showing a measurement result of direct current superposition in the inductor component of FIG. 2;

7A and 7B show a conventional inductor component, in which FIG. 7A is an overall perspective view, and FIG. 7B is an enlarged view of a gap portion.

[Explanation of symbols]

11, 31, 41 U-shaped core 12, 22, 32, 42 I-shaped core 13, 23, 33, 43 Conductor 14, 24, 34, 44 Permanent magnet 15, 25 Magnetic field due to current flowing in conductor 16, 26 Permanent magnet 27 L-shaped core 37 Substrate 51, 61 DC superposition when bias is applied 52, 62 DC superposition when bias is not applied 63 DC irreversible demagnetization due to reflow solder heat and demagnetization due to oxidation Superposition 71 EE type magnetic core 72 Permanent magnet 73 Middle leg of EE type magnetic core 74 Gap width 75 Magnet thickness 76 Clearance

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // H01F 38/02 H01F 37/02 (72) Inventor Kazuyuki Okita 6-7 Koriyama, Koriyama, Taihaku-ku, Sendai City, Miyagi Prefecture No. 1 Tokin Co., Ltd. F-term (reference) 5E040 AA03 BC01 CA01 HB06 NN01 NN12 NN18 5E041 AA02 AB01 AB02 BD03 CA01 5E070 AA11

Claims (14)

[Claims] 1. A closed magnetic circuit is formed by combining two or more cores around an outer periphery of a strip-shaped or rod-shaped conductor, and the core is combined with a core via a permanent magnet at at least one position in the closed magnetic circuit. Inductor components. 2. A closed magnetic path is formed by combining two or more cores on the outer periphery of a strip-shaped or rod-shaped conductor whose both ends are wider than a central part, and a permanent magnetic path is formed in at least one or more places in the closed magnetic path. An inductor component, wherein a core is combined via a magnet. 3. The inductor component according to claim 1, wherein forming is performed such that both ends of the conductor serve as connection terminals to a substrate. 4. The permanent magnet is unique to at least one resin selected from a polyamideimide resin, a polyimide resin, an epoxy resin, a polyphenylene sulfide resin, a silicone resin, a polyester resin, an aromatic polyamide resin, and a liquid crystal polymer. Coercive force is more than 10KOe, Tc
Is 500 ° C or more, powder average particle size is 2.5 to 25 μm, and Z
n, Al, Bi, Ga, In, Mg, Pb, Sb, and a rare earth magnet powder coated with at least one kind of metal or an alloy thereof among Sn, and the resin content is 30% by volume. % Or more, and the specific resistance is 0.1 Ωcm or more.
The inductor component according to any one of the above. 5. The composition of the rare earth magnet powder is Sm ( _Cobal. F.
e _0.15-0.25 Cu _{0.05-0 .06} Zr _0.02-0.03) inductor component according to claim 4, wherein a _7.0-8.5. 6. The inductor component according to claim 4, wherein said rare-earth magnet powder is coated with an inorganic glass having a softening point of 220 ° C. or more and 550 ° C. or less. 7. The inorganic glass has a volume ratio of 0.1 to 10%.
7. The inductor component according to claim 6, wherein 8. The inductor component according to claim 4, wherein said rare earth magnet powder is coated with a metal or an alloy and then coated with a non-metallic inorganic compound having a melting point of at least 300 ° C. or higher. 9. The method according to claim 9, wherein the metal or alloy has a volume ratio of 0.1.
9. The inductor component according to claim 8, wherein the amount is 10%. 10. The inductor component according to claim 8, wherein the amount of addition of the metal or alloy and the inorganic compound is 0.1 to 10% by volume. 11. The inductor according to claim 4, wherein said rare-earth magnet powder is magnetically anisotropic by being oriented in a thickness direction by a magnetic field when the permanent magnet is manufactured. parts. 12. The permanent magnet has a magnetizing magnetic field of 2.5T.
The inductor component according to any one of claims 1 to 11, which is as described above. 13. The permanent magnet has a center line average roughness.
The inductor component according to claim 1, wherein Ra is 10 μm or less. 14. The core is made of MnZn or NiZn.
The inductor component according to any one of claims 1 to 13, wherein the inductor component is a magnetic core made of a system ferrite, a silicon steel plate, or an amorphous.