JP2003059727A - Magnetic core and inductance component using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic core having a superior DC superimposing characteristic, core loss characteristic, and oxidation resistance. SOLUTION: In this magnetic core 3, the bonded magnet 1 inserted as a DC magnetic bias impressing magnet into a gap formed in the magnetic path of the center core of an EE-shaped core 2 made of an Mn-Zn-based ferrite is improved. In addition, the total amount of resins used in this core 3 including a binder is set to an appropriate value (>=20 vol.%) after the surface of Sm2 Co17 magnet powder having excellent magnetic characteristics as rare-earth magnet powder is coated with an epoxy resin at a volumetric ratio of 1.0-15%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic core provided with a DC magnetic bias applying magnet which is mainly applied to a choke coil or a transformer for high frequency switching power supplies and the like, and an inductance component using the magnetic core.

[0002]

2. Description of the Related Art Conventionally, good DC superposition characteristics have been required for magnetic cores used in choke coils and transformers. In particular, ferrite or dust cores are used for magnetic cores used for high frequency magnetic cores. Has been done.

Generally, a magnetic core made of ferrite has a characteristic that the initial permeability is high and the saturation magnetic flux density is small, and a dust core has a characteristic that the initial magnetic permeability is low and the saturation magnetic flux density is high. The magnetic core according to (4) is often used as an EE core having a shape in which they are butted against each other by inserting a gap between the middle legs of a pair of E cores, and the dust core is often used as a toroidal shape.

Even in the field of development of magnetic cores using such magnetic cores, it is indispensable to reduce the size of electronic components in accordance with the demand for smaller electronic devices in recent years. However, in such miniaturization, it is strongly demanded that the magnetic characteristics have a higher magnetic permeability with a larger superimposed magnetic field.

In order to improve the DC superposition characteristic, it is usually necessary to select a magnetic core having a high saturation magnetization, that is, a magnetic core which is not magnetically saturated in a high magnetic field. Since it is inevitably determined by the composition of, and it cannot be increased indefinitely, a large amount of labor has been conventionally spent to improve the saturation magnetization slightly. The current situation is that the DC superimposition characteristics have not expanded as much as expected.

As a means for solving such a problem, there has been a method of forming a magnetic core by forming a gap at one or more places of a magnetic path in a magnetic core and inserting and mounting a permanent magnet into one of the gaps. Is being considered. In the case of the magnetic core having such a structure, the result for improving the DC superposition characteristic can be obtained, but on the other hand, when a metal sintered magnet is used as the permanent magnet, the core loss of the magnetic core is significantly increased. The present situation is that no magnet having magnetic characteristics that can withstand practical use has been obtained, since problems such as looseness or the use of ferrite magnets may cause the DC superposition characteristics to become unstable.

Therefore, as a means for solving such a problem, for example, in the technique disclosed in Japanese Patent Laid-Open No. 50-133453, a permanent magnet is inserted and mounted in the gap of the magnetic core used in the magnetic core. It has been proposed to use a bond magnet obtained by mixing a rare earth magnet powder having a high magnetic force and a binder and then compression-molding the mixture magnet. With such a structure, it is possible to improve the DC superposition characteristics and the temperature rise of the magnetic core. I am supposed to.

[0008]

SUMMARY OF THE INVENTION A magnetic core using a bond magnet obtained by mixing a rare earth magnet powder having a high coercive force and a binder in a permanent magnet inserted and mounted in the gap of the magnetic core and then compression-molding the mixture. In this case, the DC superposition characteristics are certainly improved, but the demands for the improvement of the power conversion efficiency for the recent high frequency switching power supplies are becoming more severe, or choke coils and transformers are required. Even with respect to the magnetic cores used, it is considered that the merit of magnetic properties cannot be judged by simply measuring the temperature, and the excellent core loss property is also considered as an indispensable criterion. In consideration of the current situation, the core loss characteristics are actually measured according to the results of actually measuring the core loss characteristics with the core loss measuring device. There is a problem that has deteriorated.

In addition, for example, it has been recently demanded that an inductance component as an electronic component is of a surface mounting type, and a magnetic material of a permanent magnet provided in a magnetic core used for the inductance component has an oxidation resistance. Required to have.

The present invention has been made to solve the above problems, and its technical problem is to provide a magnetic core having excellent DC superposition characteristics and core loss characteristics and oxidation resistance, and a magnetic core using the same. The purpose is to provide the same inductance components as before.

[0011]

According to the present invention, the intrinsic coercive force H _{c is applied} to at least one of the gaps in the magnetic core having a gap at one or more locations in the magnetic path.
Is 7.9 × 10 ⁶ A / m or more, the Curie temperature T _c is 500 ° C. or more, and the average particle size is 2.5.
A bond magnet as a magnet for applying a DC magnetic bias, which is composed of a rare earth magnet powder of ˜50 μm and a resin containing a resin coating film formed in advance on the surface of the rare earth magnet powder in a volume ratio of 1.0 to 15%, is inserted and mounted. A magnetic core configured as described above is obtained.

Further, according to the present invention, in the above magnetic core, a magnetic core is obtained in which the resin coating is formed by repeating coating formation.

Further, according to the present invention, in any one of the magnetic cores described above, the surface of the rare earth magnet powder is previously made of Zn, Al, Bi, G before the resin coating is formed.
A magnetic core coated with at least one of a, In, Mg, Pb, Sb and Sn or an alloy thereof can be obtained.

In addition, according to the present invention, in the above magnetic core, the total amount of the resin containing the resin coating in the bonded magnet is 20 vol% or more and the specific resistance is 1 Ω.
A magnetic core of cm or more is obtained.

On the other hand, according to the present invention, in the inductance component using any one of the above magnetic cores, at least one turn of winding is wound around the bond magnet mounted in the gap of the magnetic core. An inductance component having a winding part formed by

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Examples of the magnetic core of the present invention and an inductance component using the same will be given below.
A detailed description will be given with reference to the drawings.

First, an outline of the technical development of the magnetic core of the present invention will be briefly described. In the present invention, as a result of repeated studies on a permanent magnet to be inserted and attached to at least one of the gaps in the magnetic core having a gap at one or more places in the magnetic path, a specific coercive force H _c at a specific resistance of 1 Ω · cm or more is obtained. It has been found that when a magnet powder having a magnetic field of 7.9 × 10 ⁶ A / m or more is used, an excellent direct current superposition characteristic can be obtained, and a magnetic core without deterioration of core loss characteristics can be constructed. This is because the magnet characteristics required to obtain excellent DC superposition characteristics are the intrinsic coercive force H rather than the maximum energy product (BH) _max.
Located _c, due to the discovery that sufficiently high direct current superimposition characteristic A high intrinsic coercive force H _c be used high specific resistivity magnetic powder.

A permanent magnet having a high specific resistance and a high intrinsic coercive force H _c is generally obtained by a bond magnet obtained by mixing rare earth magnet powder with a binder and then compression-molding it. Any composition having a high _c magnetic powder can be applied. Types of rare earth magnet powder are SmCo-based, NdFeB-based, SmFeN
Although it is a system, the intrinsic coercive force H _c is currently 7.9 × 10 ⁶ in consideration of the reflow conditions and the oxidation resistance for the purpose of use.
A / m or more and a Curie temperature T _c of 500
It is limited to Sm ₂ Co ₁₇ based magnet powder having a temperature of not less than 0 ° C. and an average particle size of 2.5 to 50 μm.

Further, in order to improve the oxidation resistance of the bonded magnet inserted into the gap in the magnetic core used in the magnetic core of the present invention, the volume ratio of 1.0 is previously applied to the surface of the Sm ₂ Co ₁₇ system magnet powder. Includes a resin film formed by coating in an amount of ˜15%, and the total amount of the resin composed of the resin film and the binder in the bonded magnet is 20 vo by volume.
It is preferably 1% or more, and in this case as well, the specific resistance is set to 1 Ω · cm or more. The resin coating here is preferably formed by repeating coating formation.

Further, the surface of the Sm ₂ Co ₁₇ system magnet powder is
Prior to forming the resin coating, Zn, A
It is preferable to coat with at least one of l, Bi, Ga, In, Mg, Pb, Sb and Sn or an alloy thereof.

In addition, as the material of the magnetic core, any material having a soft magnetic property suitable for a choke coil or a transformer is effective, but in general, MnZn is used.
-Based or NiZn-based ferrite, dust core, silicon steel sheet,
Since amorphous or the like is used, they may be arbitrarily selected. The shape of the magnetic core is not particularly limited, and any shape such as a toroidal core, an EE type core, an EI type core can be applied. In any case, a gap is provided in at least one location of the magnetic path of these cores, and the bond magnet having the above-described configuration is inserted and mounted in the gap. The gap length provided in the magnetic path of the core is not particularly limited, but if the gap length is too narrow, the DC superimposition characteristics will deteriorate, and if the gap length is too wide, the magnetic permeability will decrease too much. It will be decided automatically if consideration is given to the disadvantage.

The following will specifically describe the magnetic core and the inductance component using the magnetic core, including some manufacturing steps thereof, including some examples.

(Example 1) In Example 1, first, the average particle size of rare earth magnet powder for obtaining a bonded magnet was about 5 μm.
with Sm ₂ Co ₁₇ magnet powder of m, the Sm ₂ Co ₁₇
A resin coating made of an epoxy resin is formed on the surface of the system magnet powder at a volume ratio of vol% of 0.5, 1.0, 2.0, 5.
A mixture was obtained by kneading the epoxy resin using a pressure kneader so as to form a coating as 0, 10.0, 15.0, 20.0, and then mixing this mixture with 15
The lump obtained by curing at 0 ° C. was crushed with a raikai machine to be pulverized. However, it was difficult to disintegrate the sample in which the resin film made of the epoxy resin was formed by coating at a volume ratio of 20.0 vol%, so that it could not be pulverized.

Next, with respect to each sample of the Sm ₂ Co ₁₇ magnet powder coated with these resin coatings, an epoxy resin was applied to each sample so that the total amount of the resin was 50% by volume. After mixing the binder according to 1., the die was molded in a non-magnetic field to produce a bonded magnet for each sample.

On the other hand, the magnetic core made of Mn-Zn ferrite material as the magnetic core has a magnetic path length of 7.5 cm and an effective area of 0.74.
cm EE type core was prepared, and a gap of 1.5 mm was applied to the center of the EE type core, and the EE type core was processed to have a height of 1.5 mm in conformity with the cross section of the center side of the EE type core. After the bond magnet according to each sample was magnetized in the magnetic path direction with a pulse magnetic field of about 10 T, the bond magnet according to each sample was inserted and mounted in the gap of the EE type core to manufacture the magnetic core according to each sample.

FIG. 1 is a perspective view showing an external configuration of the magnetic core 3 according to the first embodiment of the present invention manufactured in this manner. The magnetic core 3 is configured by inserting and mounting the bond magnet 1 according to each of the samples described above into the gap formed in the magnetic path of the core of the EE type core 2.

Incidentally, the magnetic core 3 thus obtained is, as shown in the side view of FIG. 2, the bond magnet 1 mounted in the gap of the EE type core 2 which is the magnetic core of the magnetic core 3. An inductance component 5 is formed by winding a winding of at least one turn around the periphery and providing the winding portion 4.

Table 1 shows the demagnetization rate (%) obtained by measuring the flux of the bonded magnet according to each sample before and after the reflow.
The result of examination of Sm ₂ Co ₁₇
It is shown in comparison with a bonded magnet manufactured by the same procedure except that no coating is formed on the surface of the system magnet powder. Further, Table 2 shows the results of measuring the specific resistance of the bonded magnets of the respective samples before and after the reflow, except that a resin coating as a comparative example is not formed on the surface of the Sm ₂ Co ₁₇ system magnetic powder. It is shown in comparison with a bonded magnet manufactured by a similar procedure.

[0029]

[Table 1]

[Table 2] However, the reflow condition is that the bonded magnets of each sample were held as a reflow furnace in a constant temperature bath at 270 ° C. for 30 minutes, cooled to room temperature and left for 2 hours.
The measurement results of the flux and the specific resistance in Table 2 include the measurement results before and after such reflow.

From Tables 1 and ₂ , if the coating amount (resin coating amount) of the resin coating on the Sm ₂ Co ₁₇ type magnet powder is 1 vol% or more in volume ratio, the demagnetization rate (core loss) without changing the flux. It can be seen that the specific resistance can be improved.

FIG. 3 shows a magnetic core formed by inserting and mounting a bond magnet, which is formed by coating the resin coating of each sample here on the surface of Sm ₂ Co ₁₇ system magnet powder, into the EE type core gear. Frequency characteristic of permeability μ of frequency f
Due to the relationship of magnetic permeability μ [-] with respect to [kHz], a bond magnet in which a resin film as a comparative example is not formed on the surface of Sm ₂ Co ₁₇ system magnet powder is inserted and mounted in the EE type core gearup. The magnetic core and the bonded magnet are shown in comparison with a magnetic core (AirGAP) configured without inserting and mounting the magnetic core and the bonded magnet into the EE type core.

From FIG. 3, the frequency characteristic of permeability μ is
It can be seen that the one having the higher specific resistance extends to the high frequency band (note that the data of coating 15 vol% almost overlaps the data of coating 10 vol% in FIG. 3 and is difficult to determine). Further, the DC superposition characteristic shows the same tendency as that of the flux, and it was confirmed that the permeability μ can be extended up to a high magnetic field by inserting and mounting a bond magnet formed by coating a resin film.

In Example 1 above, the specific resistance was high when the coating amount (resin coating amount) of the resin coating on the Sm ₂ Co ₁₇ system magnet powder was 1 vol% or more,
The oxidation resistance and the demagnetization rate are improved and a magnetic core with good characteristics can be obtained, as compared with the case of using a bond magnet in the case where the resin coating is not formed by coating the Sm ₂ Co ₁₇ type magnet powder, and further the resin coating It was found that if the amount was 20 vol% or more, it could not be pulverized and it was difficult to carry out (apply).

(Example 2) In Example 2, first, as the rare earth magnet powder for obtaining the bonded magnet, the same average particle size as in Example 1 was used with respect to the Sm ₂ Co ₁₇ based magnet powder having an average particle size of about 5 μm. 3 wt% of Zn metal powder having a particle size of about 5 μm was mixed, and heat treatment was performed for 2 hours in an Ar atmosphere at a temperature of 500 ° C., so that the surface of the Sm ₂ Co ₁₇ based magnet powder was coated with Zn. ₂ Co ₁₇ magnet powder was obtained.

Next, the Sm ₂ Co ₁₇ type magnet powder was kneaded with an epoxy resin in an amount of 1.0 vol% with stirring, and the resulting kneaded product was cured at 150 ° C. and then crushed by a liquor machine to be powdered. I went.

Furthermore, the same process as described above is applied to this powder.
In other words, that is, by kneading the epoxy resin with 1.0 vol% with stirring.
After curing the resulting kneaded material at 150 ° C, use a raikai machine.
By repeating the process of crushing and pulverizing,
Zn coated with Sm₂Co ₁₇On the surface of the magnetic powder
Resin that forms a resin coating with a epoxy resin
Coating is carried out step by step from 1 to 5 times,
Make sure to sample every resin coating
For each sample of each powder obtained by
Epoxy resin so that the volume is 50% by volume
After mixing the binder according to
As a result, a bonded magnet according to each sample was manufactured.

These bond magnets were processed into the same shape as in Example 1 and magnetized with a pulse magnetic field of about 10 T, and then the bond magnets of each sample were inserted and mounted in the gaps of the EE type core. A magnetic core according to the sample was manufactured.

Table 3 shows the demagnetization rate (%) obtained by measuring the flux of the bonded magnet according to each sample here before and after the reflow.
The result of examination of Sm ₂ Co ₁₇
Volume ratio of 1.0, 2.0,
It is shown in comparison with the bonded magnet in which the coating was formed only once at 5.0 vol%. Further, Table 4 shows the results obtained by measuring the specific resistance of the bonded magnet according to each sample here before and after the reflow, and showing the resin coating as a comparative example with Sm ₂ C.
1.0,2 each volume on the surface of the o ₁₇ based magnetic powder.
It is shown in comparison with the bonded magnet in which the coating was formed only once at 0,5.0 vol%. Incidentally, the bonded magnet according to each sample, which is a comparative example here, corresponds to the one described in the first embodiment, and is therefore merely a comparative example in the second embodiment.

[0039]

[Table 3]

[Table 4] Also, the reflow conditions here are the same as in the case of Example 1, and the measurement results of the flux in Table 3 and the specific resistance in Table 4 include the measurement results before and after the reflow.

From Tables 3 and 4, although almost no difference in flux was observed, the specific resistance was improved as the number of resin coatings was increased, and the resin coating was repeatedly performed even with the same resin coating amount. It can be seen that higher results will be obtained. Also here, the bonded magnet (of this embodiment) according to each sample is inserted and mounted in the gearup of the EE type core to form the magnetic core according to each sample, and the magnetic permeability μ is the same as in the case of the first embodiment. As a result of measuring the frequency characteristics of, it was confirmed that the permeability μ of the sample having a high specific resistance extends to a high frequency.

In Example 2 described above, if the resin film coating (resin coating) is repeatedly formed on the Sm ₂ Co ₁₇ magnet powder whose surface is previously coated with Zn, the resin film is formed once. It was found that a magnetic core having a higher specific resistance than that of the above case and having excellent specific resistance and demagnetization rate (core loss) with good characteristics can be obtained.

(Example 3) In Example 3, first, as the rare earth magnet powder for obtaining the bonded magnet, the same average particle size as in Example 2 was used with respect to the Sm ₂ Co ₁₇ system magnet powder having an average particle size of about 5 μm. 3 wt% of Zn metal powder having a particle size of about 5 μm was mixed, and heat treatment was performed for 2 hours in an Ar atmosphere at a temperature of 500 ° C., so that the surface of the Sm ₂ Co ₁₇ based magnet powder was coated with Zn. ₂ Co ₁₇ magnet powder was obtained.

Next, the kneaded material obtained by stirring and kneading the Sm ₂ Co ₁₇ type magnet powder with an epoxy resin in an amount of 10 vol% was cured at 150 ° C. and then crushed by a liquor machine to be pulverized. It was As a result, a resin coating for forming a resin coating of an epoxy resin on the surface of the Sm ₂ Co ₁₇ based magnet powder, the surface of which was previously coated with Zn, was applied.

Further, the total amount of the resin in the resin-coated powder is 2% in volume ratio.
A binder made of an epoxy resin was mixed so as to be 0, 30, 40, and 50, and then a die-molding was performed in a non-magnetic field to produce a bonded magnet for each sample.

These bond magnets were processed into the same shape as in Example 1 and magnetized with a pulse magnetic field of about 10 T, and then the bond magnets of the respective samples were inserted and mounted in the gaps of the EE type core. A magnetic core according to the sample was manufactured.

Table 5 shows the demagnetization rate (%) obtained by measuring the flux of the bonded magnet according to each sample before and after the reflow.
The result of examination of Sm ₂ Co ₁₇
It is shown in comparison with a bonded magnet manufactured by the same procedure except that no coating is formed on the surface of the system magnet powder. Further, Table 6 shows the results of measuring the specific resistance of the bonded magnets of the respective samples before and after the reflow, except that the resin coating as a comparative example was not formed on the surface of the Sm ₂ Co ₁₇ system magnet powder. It is shown in comparison with a bonded magnet manufactured by a similar procedure.

[0047]

[Table 5]

[Table 6] However, the reflow conditions here are also the same as in the case of Example 1, and the measurement results of the flux in Table 5 and the specific resistance in Table 6 include the measurement results before and after such reflow.

From Tables 5 and 6, there is almost no difference in the flux, but the total amount of the entire resin is 20 v in terms of volume ratio.
It can be seen that even a sample with ol% can obtain a specific resistance of 1 Ω · cm or more. Although not shown in the table, it was found that when the total volume of the entire resin was 20 vol% or less, the specific resistance was 1 Ω · cm or less. Further, here as well, the bonded magnet (of this embodiment) according to each sample is inserted and mounted in the gearup of the EE type core to form the magnetic core according to each sample, and the magnetic permeability μ is the same as in the case of the first embodiment. As a result of measuring the frequency characteristics and DC superposition characteristics, the DC superposition characteristics extend up to a high magnetic field when the total amount of resin is small regardless of the presence or absence of resin coating, and the resin coated samples are transparent. It was confirmed that the frequency characteristic of magnetic susceptibility μ extends to high frequencies. In particular, it was found that the frequency characteristic of the magnetic permeability μ became remarkable when the total amount of the resin was 20 vol% as in the case of the specific resistance.

In Example 3 described above, the Sm ₂ Co ₁₇ magnet powder whose surface was previously coated with Zn was coated with a resin film (resin coating), and then the total amount of the resin was adjusted to an appropriate amount. , The specific resistance is higher than in the case where the resin film is not formed, and the total amount of the resin can be reduced while maintaining the specific resistance of 1 Ω · cm or more, which is excellent with excellent specific resistance and demagnetization rate (core loss). It was found that a characteristic magnetic core can be obtained.

(Example 4) In Example 4, first, as a rare earth magnet powder for obtaining a bonded magnet, the same average particle size as in Example 2 was used with respect to Sm ₂ Co ₁₇ based magnet powder having an average particle size of about 5 μm. 3 wt% of Zn metal powder having a particle size of about 5 μm was mixed, and heat treatment was performed for 2 hours in an Ar atmosphere at a temperature of 500 ° C., so that the surface of the Sm ₂ Co ₁₇ based magnet powder was coated with Zn. ₂ Co ₁₇ magnet powder was obtained.

Next, a polyamide imide resin having a solid content ratio of 15% was added to the Sm ₂ Co ₁₇ magnet powder by NMP.
The volume ratio of the solution diluted 0 times to the resin solid content is 10
The kneaded product obtained by kneading with a pressure kneader so as to have a vol% is preliminarily dried under the condition of a temperature of 80 ° C. so as to volatilize the solvent, and the lump obtained here is removed by a liquor machine. After crushing and pulverizing with, temperature condition 200 ℃
And heat treated for 30 minutes. As a result, a resin coating was formed on the surface of the Sm ₂ Co ₁₇ type magnet powder, the surface of which was previously coated with Zn, to form a resin film of a polyamideimide resin.

Further, a binder of PAI resin was mixed with the resin-coated powder so that the total amount of the resin was 50% by volume, and a slurry having a viscosity of about 300 P was obtained. Thick film 100, 200, 500μ with a doctor blade
The bonded magnet according to each sample was manufactured by processing so as to have a sheet shape of m.

These bond magnets were processed into a shape to be inserted and mounted in the gap of the EE type core in the same manner as in Example 1, magnetized with a pulse magnetic field of about 10 T, and then the gap of the EE type core (here, (Thick films 100, 200, and 500 μm in thickness are prepared), and the bond magnets of each sample are inserted and attached to produce magnetic cores of each sample.

Table 7 shows the results obtained by measuring the specific resistance of the bonded magnets of the respective samples before and after the reflow, except that the resin coating as a comparative example was not formed on the surface of the Sm ₂ Co ₁₇ magnet powder. Is shown in comparison with a bonded magnet manufactured by the same procedure.

[0055]

[Table 7] However, the reflow conditions here are the same as in the case of Example 1, and the measurement results of the specific resistance in Table 7 include the measurement results before and after the reflow.

From Table 7, the resin coating is Sm₂Co₁₇System magnet
Bonded magnet with no coating formed on the surface of stone powder
In contrast, while the specific resistance decreases due to the decrease in film thickness,
Sm resin coating₂Co₁₇Coating on the surface of magnetic powder
In the case of the formed sample, even if the film thickness is 100 μm,
It can be seen that a specific resistance of Ω · cm or more can be obtained. Also here
Then, only the specific resistance of the bonded magnet was described, but the examples
As in the case of 1, the magnetic core is configured and the frequency of permeability μ
When the characteristics were measured, the resin coating was Sm₂Co ₁₇System magnet
Permeability μ of the sample formed by coating on the powder surface
It has been confirmed that the frequency characteristics of (1) extend to high frequencies.

In Example 4 above, the resin coating was Sm ₂ C
o If the total amount of resin after coating on the surface of the _17- based magnet powder is adjusted to an appropriate amount and the film thickness of the bond magnet is selected and specified within a predetermined range, the resin coating will be Sm ₂ C
o It is possible to obtain a sheet-shaped bonded magnet having a higher specific resistance than when a coating is not formed on the surface of _17- based magnet powder, and to obtain a magnetic core having excellent specific resistance and demagnetization ratio (core loss). I understood.

In Examples 2 to 4 described above, the case where Zn was used as the metal powder with which the surface of the Sm ₂ Co ₁₇ system magnet powder was coated in advance before the coating of the resin coating was formed was described. Other metals can also be applied, for example, Al, Bi, Ga, I
The same effect can be obtained by using at least one of n, Mg, Pb, Sb and Sn, or an alloy thereof.
Further, regarding the resin material, in each of the examples, a case where an epoxy resin or an amide imide resin is used as a resin coating material coated on the surface of the Sm ₂ Co ₁₇ system magnet powder, and a case where an epoxy resin or a PAI resin is used as a binder is used. As described above, any other resin material having heat resistance can be applied.

[0059]

As described above, according to the magnetic core of the present invention, the bond magnet as the DC magnetic bias applying magnet which is inserted and mounted in the gap formed in the magnetic path of the magnetic core is improved, and the rare earth element is improved. Sm ₂ with excellent magnetic properties as a magnet powder
A resin coating film is previously formed on the surface of the Co ₁₇ magnet powder at a volume ratio of 1.0 to 15%, and the total amount of the resin including the binder is set to an appropriate amount. _Since the surface of the ₂ Co ₁₇ magnet powder is coated with a low melting point metal or its alloy, excellent DC superposition characteristics and core loss characteristics,
Also, a magnetic core having oxidation resistance can be obtained. As a result, even in the case of a high frequency inductance component having a winding part formed by winding at least one turn of winding around the bond magnet mounted in the gap of the magnetic core in this magnetic core, Application as an implementation type is effective.

[Brief description of drawings]

FIG. 1 is a perspective view showing an external configuration of a magnetic core according to a first embodiment of the invention.

2 is a side view showing an inductance component configured by winding a winding around the magnetic core shown in FIG. 1. FIG.

FIG. 3 is formed by inserting and mounting a bond magnet formed by coating a resin coating according to each sample of Example 1 described in FIG. 1 on the surface of Sm ₂ Co ₁₇ system magnet powder into a gearup of an EE type core. The frequency characteristic of the magnetic permeability of the magnetic core is Sm
_{2 A} magnetic core configured by inserting and mounting a bond magnet without coating formed on the surface of Co ₁₇ type magnet powder into the EE type core gearup and a bond magnet configured without inserting and mounting the bond magnet into the EE type core gearup. It is shown in comparison with a magnetic core.

[Explanation of symbols]

1 Bond magnet 2 EE type core 3 magnetic core 4 winding part 5 Inductance parts

Continued front page    (72) Inventor Haruki Hoshi             6-7-1, Koriyama, Taihaku-ku, Sendai City, Miyagi Prefecture             Tokin Co., Ltd. (72) Inventor Keita Isoya             6-7-1, Koriyama, Taihaku-ku, Sendai City, Miyagi Prefecture             Tokin Co., Ltd. F-term (reference) 5E062 CC04 CD05 CG07                 5E070 BA08 BB03 BB05

Claims (5)

[Claims] 1. An intrinsic coercive force H _c is 7.9 × 10 ⁶ A / m or more with respect to at least one of the gaps in a magnetic core having a gap at one or more locations in a magnetic path, and Curie temperature T _c is 500 ° C. or higher,
And a rare earth magnet powder having an average particle size of 2.5 to 50 μm,
A volume ratio of 1.0 to 15% was previously applied to the surface of the rare earth magnet powder.
2. A magnetic core comprising a bonded magnet as a magnet for applying a DC magnetic bias, which is made of a resin containing a resin film formed by coating. 2. The magnetic core according to claim 1, wherein the resin coating film is formed by repeating the coating formation. 3. The magnetic core according to claim 1 or 2, wherein the surface of the rare earth magnet powder is previously formed of Zn, Al, Bi, Ga, before forming the coating of the resin film.
A magnetic core characterized by being coated with at least one of In, Mg, Pb, Sb and Sn or an alloy thereof. 4. The magnetic core according to claim 3, wherein a total amount of the resin containing the resin coating in the bonded magnet is 20 vol% or more and a specific resistance is 1 Ω.
A magnetic core having a size of at least cm. 5. The inductance component using the magnetic core according to claim 1, wherein at least one turn is made around the bond magnet mounted in the gap of the magnetic core. An inductance component comprising a winding portion formed by winding a winding wire.