JP2002313632A - Magnetic element and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily obtain a small-sized high-performance magnetic element with small variation. SOLUTION: This magnetic element has a bobbin which is constituted at least of magnetic powder, an organic resin, and a coil and incorporates the coil and a second magnetic material which is brought into contact with the bobbin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic element used for an inductor, a choke coil, a transformer and the like of an electronic device and a method of manufacturing the same.

[0002]

2. Description of the Related Art As electronic devices become smaller and thinner, there is a strong demand for parts and devices used in these devices to be made smaller and thinner. On the other hand, LSIs such as CPUs are becoming faster and more integrated, and a power supply circuit supplied thereto may be supplied with a current of several A to several tens A. Therefore, for inductors such as choke coils used in these devices, in addition to the demand for miniaturization, it is necessary to realize low heat generation by lowering the resistance of the coil conductor and to minimize the decrease in inductance due to DC superposition. Have been. Further, the operating frequency is increasing, and it is required that the loss at the high frequency be low. Further, it is strongly demanded to reduce the cost of parts, and it is necessary to assemble component components having a simple shape in a simple process. That is, it is required to supply a magnetic element which can be used at a large current and a high frequency and is as small and thin as possible at a low cost.

As a desired characteristic of a magnetic material used in such a magnetic element, the higher the saturation magnetic flux density, the better the DC superimposition characteristic is. The higher the magnetic permeability, the higher the inductance value is obtained, but the magnetic saturation is more likely to occur, so that the DC superposition characteristics deteriorate. For this reason, it is a problem that it is too low, but the higher the value, the better it is, and it is selected depending on the application. Further, it is desirable that the electric resistivity is high and the magnetic loss is low. Materials actually used are broadly classified into ferrite and metal magnetic systems. Ferrite material itself has high permeability, low saturation magnetic flux density, high electrical resistance,
Low magnetic loss. The metal magnetic system, the material itself,
High magnetic permeability, high saturation magnetic flux density, low electric resistance and high magnetic loss.

[0004] As inductors actually used,
The most common method is to use an EE type or EI type ferrite core and coil. In this method, since the ferrite material has a high magnetic permeability and a low saturation magnetic flux density, if it is used as it is, the decrease in inductance due to magnetic saturation is large, and the DC superimposition characteristics are deteriorated. Therefore,
In order to improve the direct current superimposition characteristic, a gap is usually provided somewhere in the magnetic path of the core to reduce the apparent magnetic permeability. However, in this method, when driven by an alternating current, the core vibrates in the gap portion, and noise noise is generated. Further, since the saturation magnetic flux density remains low even if the magnetic permeability is lowered, there is a problem that the DC superposition characteristic is worse than that of the metal magnetic material.

Next, as a core material, an Fe—Si—Al alloy having a higher saturation magnetic flux density than ferrite, Fe—N
In a method using an i-based alloy or the like, these metallic materials are
Since the electric resistance is low, the operating frequency is several hundred K recently.
As the frequency becomes higher from Hz to MHz, the eddy current loss increases and cannot be used as it is. For this reason, a thin magnetic material is laminated through an insulating layer, or a powder magnetic material is molded at a high density, a so-called dust core, or a composite magnetic material in which magnetic powder is dispersed in resin. Is being developed.

Among these, the method of laminating a thin metal magnetic material via an insulating layer has a high saturation magnetic flux density, but requires a gap due to high magnetic permeability, and can be used at high frequencies. Since such a thin body needs to be sufficiently thin, there is a problem that the cost is high and a complicated shape cannot be produced. To obtain a sufficiently high saturation magnetic flux density and a practically high magnetic permeability, the dust core must
It is necessary to fill by applying a very high pressure of about 30 t / cm ^2, which requires a special high-strength mold,
In addition, it is difficult to produce a complicated shape. Further, there is a problem that insulation is necessary because the electric resistance itself is low.

On the other hand, the composite magnetic material can be made of an insulator, and has a feature that a magnetic path cross-sectional area can be increased by embedding a coil conductor therein, and it is relatively easy to manufacture. And has the feature of being low cost. For this reason, conventionally, ferrite powder or metal magnetic powder is mixed with a resin, placed in a mold in which a coil is inserted, and solidified (JP-A-54-163354, JP-A-63-186409, Kaihei 1-25
3906, JP-A-2-226799, JP-A-4-83320, etc.) have been proposed. However, the composite magnetic material has a problem that the saturation magnetic flux density is lower than that of the magnetic material powder itself, and the magnetic permeability is extremely lower than that of ferrite or dust core, and a large inductance value cannot be obtained.

In order to compensate for the disadvantage of the composite magnetic material having an extremely low magnetic permeability, it has been proposed to further improve the characteristics by using a composite magnetic material in combination with a plurality of magnetic materials. A coil is inserted into a cup-shaped magnetic material core, and the inside of the cup is filled with a composite magnetic material (Japanese Utility Model Application Laid-Open No. Sho 59-33216), or a coil is wound around a ferrite core with a brim, and this is mixed with magnetic powder and resin. Dipped in a mixture of materials (Japanese Unexamined Patent Publication No.
No. 36213), a ferrite sintered body which is wound and then covered with a composite magnetic material (Japanese Patent Laid-Open No.
Japanese Patent Application Laid-Open No. Hei 9-84648), two sheets of magnetic metal thin bodies laminated are prepared, a planar coil is disposed between the two sheets, and the magnetic powder is fixed with an adhesive dispersed therein. -270334) is said to be effective for miniaturization of inductors. Although a miniaturization is not intended, a transformer in which a planar coil is arranged between two ferrite thin plates and fixed with an adhesive in which ferrite powder is dispersed (Japanese Unexamined Patent Application Publication No. 6-34
No. 2725) has been proposed.

[0009]

However, these methods using a combination of a normal magnetic material and a composite magnetic material are characterized in that the normal magnetic material and the composite magnetic material are integrated. There has been a problem that the characteristics of the obtained elements vary greatly due to the effect of resin shrinkage during integration and the displacement of the built-in coil.

[0010] In addition, when a high pressure is applied to the composite magnetic material at the time of fabrication to increase the packing ratio of the magnetic material powder inside the composite to obtain higher characteristics, pressure is also applied to a normal magnetic material. There has been a problem that ordinary magnetic materials are cracked or cracked, resulting in deterioration of characteristics.

[0011]

In order to solve the above-mentioned problems, a magnetic element according to the present invention comprises a bobbin having a built-in coil, which comprises at least a magnetic powder, an organic resin and a coil, and is in contact with the bobbin. And a second magnetic material. At this time, it is desirable that the bobbin containing the coil has a hole, and a part of the second magnetic body inserted into the hole of the bobbin is inserted. The magnetic powder constituting the bobbin may be ferrite, but it is a metal magnetic material and further contains at least one other insulating material, and the filling rate of the metal magnetic material is 70% by volume or more and 90% by volume or less. Is desirable.

Usually, the bobbin refers to a core or a frame made of resin or the like around which the coil is wound. As described here, the member containing the coil, which is composed of at least a magnetic powder, an organic resin, and a coil, does not wind the coil around it as a normal bobbin, but has a role of supporting the coil, Since it plays the same role as a bobbin wound with, it is called a bobbin here.

[0013] The method for producing a magnetic element of the present invention comprises at least a mixing step of mixing an organic resin with the magnetic powder;
Forming the mixture obtained in the mixing step into a bobbin of a predetermined shape while incorporating a coil by an injection molding method or a transfer molding method, and a step of combining the bobbin with a second magnetic body. Or a step of sieving the mixture of the magnetic powder and the organic resin into granules, a step of pressing the granules in a mold into a bobbin of a predetermined shape while incorporating a coil, and a step of forming the bobbin and the second And a step of combining with a magnetic material.

[0014]

Embodiments of the present invention will be described below. Hereinafter, only the primary winding, an example of a magnetic element used for a choke coil or the like will be described. However, the present invention is not limited to this, and may be used for a transformer or the like requiring a secondary winding. The effect is exhibited.

(Embodiment 1) A magnetic element according to the present invention comprises:
It is composed of at least two types, a composite magnetic bobbin with a built-in coil and a second magnetic body. First, a composite magnetic bobbin with a built-in coil is composed of at least a magnetic powder, an organic resin, and a built-in coil, and further contains one or more types of insulating materials as necessary. .

As the magnetic material powder, ferrite magnetic material such as MnZn ferrite or NiZn ferrite, or metal magnetic powder containing Fe, Ni or Co as a main component can be used. Ferrites are desirable when used in transformers and the like because they have the characteristics of easily increasing the electrical resistance and having low magnetic loss. On the other hand, a metal-based material is originally desirable for use in a choke coil or the like because it has a high saturation magnetic flux density and a high filling density can be obtained by pressure molding. Specific examples of the metal magnetic material include Fe powder, Fe-Si, Fe-
Si-Al, Fe-Ni, Fe-Co, Fe-Mo-N
An i-based alloy or the like can be used. However, the magnetic element F
When the amount of sub-components other than e, Ni, and Co increases, the saturation magnetic flux density decreases and the metal powder itself hardens. Therefore, these sub-components total 10 wt% or less, more preferably 6 wt%.
% Or less is good.

However, with a metal powder consisting of only a magnetic metal, the electric resistance value and the withstand voltage may be insufficient.
From this point, Si, Al, Cr, Ti, Zr, Nb,
When metal magnetic powder containing Ta in a total amount of 10 wt% or less is used, these components become concentrated and contained in a natural oxide film which is very slightly present on the surface, and the resistance value of the insulating film and It is desirable because the withstand voltage is improved. Also,
Al, Cr, Ti, Zr, Nb, and Ta are more desirable because they also improve rust resistance. In addition to these, O, C, M
Even if components such as n and P are contained in the raw material metal or mixed in the production process of the magnetic metal powder, there is no problem as long as the amount is small. Note that a mixture of ferrite-based magnetic powder and metal-based magnetic powder may be used.

When a metal magnetic powder is used, the insulation resistance may be insufficient depending on the filling rate even with the above composition. At this time, the resistance is increased by using another kind of insulating material. The insulating method includes: 1) adding a silicon compound, an organic titanium compound, water glass, etc. to cover the surface of the magnetic powder; 2) treating the metal magnetic powder with an acid or heating in the presence of oxygen; Then, an insulating oxide film is formed on the surface. 3) Dispersing the insulating powder to reduce the probability of contact between the metallic magnetic powders to increase the electric resistance. Of these, the powder addition method is the easiest to implement. As a powder that has a great effect when actually used,
The shape is plate-like or needle-like, boron nitride, talc, mica, zinc oxide, titanium oxide, silicon oxide, aluminum oxide, iron oxide, barium sulfate, etc.
Fluororesin (such as tetrafluoroethylene) powder and stearates are desirable.

The volume fraction of these insulating particles in the whole magnetic material is 1 to 20% by volume, more preferably 1 to 20% by volume.
0 volume percent or less is good. If it is less than this, the electric resistance is too low, and if it exceeds this, the magnetic permeability and the saturation magnetic flux density become too low, which is disadvantageous. It should be noted that these insulating substances are not usually required if the magnetic powder is ferrite-based, but they are effective when used to further improve the dielectric strength.

Any organic resin can be used as long as it has a binding property. However, the organic resin has a role of solidifying the entire composite magnetic bobbin as a molded body and incorporating a coil. Therefore, it is desirable to use a thermosetting resin. Epoxy resin, phenol resin, silicone resin, etc. can be used as the thermosetting resin,
In order to improve the dispersibility with the metal magnetic powder, a small amount of a dispersant or the like may be added. Further, a small amount of a plasticizer or the like may be appropriately added.

The shape of the conductor coil incorporated in the composite magnetic bobbin may be a round wire, a rectangular wire, a foil wire, or the like, depending on the structure and application, and the required inductance and resistance. As the material of the conductor, a low resistance is desirable, so that copper or silver, usually copper may be used. It is desirable that the surface be covered with an insulating resin.

The mixing ratio of the magnetic powder and the resin in the composite magnetic bobbin may be changed according to the type of the magnetic powder and the final filling ratio. That is, resin volume% ≦
100-magnetic material powder filling volume%-insulating material volume%. When ferrite is used for the magnetic powder, the filling volume% is about 65 to 70% at the upper limit, and when the amount of resin is small, voids are reduced. Therefore, the volume may be increased to about 20 to 50% by volume. When the magnetic powder is a metal-based material, if the pressure molding is performed, the filling rate can be further increased. Therefore, it is better that the amount of the resin is small, but if the amount is too small, the strength is reduced. , More preferably 10% by volume or more. On the other hand, the upper limit may be changed according to the target filling rate of the metal magnetic powder.

As a molding method of the mixture of the magnetic powder and the resin component, two types of molding methods, injection molding or transfer molding, and pressure molding from a powder state can be considered. The former injection molding or transfer molding is selected when it is not necessary to increase the filling rate of the magnetic powder so much or when it is desired to make the shape slightly complicated. In these molding methods, it is desirable to make the amount of resin relatively large. Injection molding is generally performed when a thermoplastic resin is used, in which a mixture of a magnetic powder and a resin component is heated to a liquid state, and is injected into a low-temperature mold and solidified. On the other hand, transfer molding is generally performed when a thermosetting resin is used, and a liquid mixture of a magnetic powder and a resin component is poured into a heated mold and solidified. A composite magnetic bobbin with a built-in coil is obtained by inserting a coil and, if necessary, a terminal portion into the mold in advance.

The latter pressure molding from the powder state is selected when it is desired to increase the filling ratio of the magnetic powder as much as possible. In this molding method, it is desirable to use a thermosetting resin with a relatively small amount of resin. In this case, the powder is filled in a mold and molded by applying a pressure of about 1 to 10 t / cm ² . Next, the obtained molded body is heated to cure the resin. However, the resin may be cured by simultaneously raising the temperature to the curing temperature of the thermosetting resin during pressure molding in a mold. A composite magnetic bobbin with a built-in coil is obtained by inserting a coil and, if necessary, a terminal portion into the mold in advance.

In this method, when the metal magnetic powder is used, the metal is plastically deformed, so that a high filling rate can be obtained. However, if the filling rate is too high, the electrical resistivity will decrease even if an insulating material is mixed. May be changed. The upper limit of the filling rate is 90%
It is about.

In this molding method, it is necessary that the mixture of the magnetic powder and the resin be filled in the mold without forming a large gap, so that good flow is desired. Therefore, the mixture of magnetic powder and resin, such as by once passing through a mesh,
Granulated granules are easier to use because the flowability of the powder is improved. Here, the granules are a plurality of metal magnetic powders that are softly bound by a resin, and the fluidity increases as the particle diameter becomes larger than the particle diameter of the metal magnetic powder itself. The granule size is naturally larger than the particle diameter of the metal magnetic powder, and is about several mm or less, usually 1 m.
m or less is good.

With respect to the mixing of the metal magnetic powder and the insulating powder, both may be mixed in advance, and then the organic resin component may be mixed, or all three may be mixed at once, but part of them may be mixed. After mixing with the metal magnetic powder, and then mixing the organic resin component and sizing the mixture into granules, the remaining insulating powder may be mixed.

Next, the second magnetic material is desired to have a high magnetic permeability, a high saturation magnetic flux density and excellent high frequency characteristics. Materials that can actually be used include:
Sintered ferrite such as MnZn ferrite or NiZn ferrite, Fe powder, Fe-Si-Al alloy, Fe-
A dust core obtained by solidifying a magnetic metal powder such as a Ni-based alloy with a binder such as a silicone resin or glass and densifying it to a filling rate of about 90% or more is exemplified. Among them, the ferrite sintered body has high magnetic permeability, excellent high frequency characteristics, and low cost, but has a low saturation magnetic flux density. The dust core has a high saturation magnetic flux density and can secure high frequency characteristics to some extent, but has a lower magnetic permeability than ferrite. Therefore, depending on the application,
You can choose from these. Note that one inductor may be used in combination of two or more types of second magnetic material, for example, a NiZn ferrite sintered body and a dust core.

Next, an embodiment of the present invention will be described with reference to the drawings. 1 and 2 are a perspective view and a sectional view showing an example of a composite magnetic bobbin incorporating a coil according to the present invention. FIGS. 3, 4 and 5 are a perspective view and a sectional view showing an example of the magnetic element of the present invention.
1A to 5, (a) is a perspective view of a magnetic element,
FIG. 2B is a cross-sectional view taken along the line AA ′ of FIG.

FIG. 1 shows a case where the magnetic bobbin has no hole, and FIG. 2 shows a case where the magnetic bobbin has a circular through hole as the hole. In FIG. 1, a coil 11 is embedded in a composite magnetic body 12, a terminal is drawn out to the surface of the composite magnetic body 12, and an electrode 13 is provided.
Is provided. FIG. 2 also has the same structure as FIG. 1, except that a hole 14 is provided so as to pass through the center of the coil.

FIG. 3 shows an example of the magnetic element of the present invention manufactured using the composite magnetic bobbin of FIG. A flat second magnetic body 15 is adhered to the upper and lower surfaces. FIGS. 4 and 5 show examples of the magnetic element of the present invention produced using the composite magnetic bobbin of FIG. In the case of FIG. 4, a plate-shaped second magnetic body and a second magnetic body having a pillar portion that can be inserted into the through hole of FIG. 2 are used, and both are in direct contact at the end of the hole. In the case of FIG. 5, two second magnetic bodies having a pillar portion in the center and U-shaped ends are used, and both are in direct contact outside the composite magnetic bobbin. An air gap 16 is provided in the through hole at the center of the bobbin, so that the bobbin does not directly contact.

In the structures shown in FIGS. 3 and 4, most of the magnetic flux passing through the second magnetic body also passes through the composite magnetic body, and does not have a closed magnetic circuit structure including only the second magnetic body.
In the structure of FIG. 5, if the air gap 16 is not provided and the second magnetic body is in direct contact, a closed magnetic circuit structure including only the second magnetic body is obtained. With such a closed magnetic circuit structure, since the magnetic permeability of the second magnetic body is much higher than that of the composite magnetic body, the magnetic flux concentrates on the second magnetic body, and the effect of using the composite magnetic bobbin is reduced. Therefore, the second
It is desirable that the magnetic circuit composed of only a magnetic material does not form a closed magnetic circuit, and has a structure in which an air gap or a gap formed by a composite magnetic material exists. Also, considering the leakage of magnetic flux to the outside of the element, it is desirable that this gap be located inside the outer surface of the element, and therefore, it is desirable that the gap be located in a hole provided in the composite magnetic bobbin. Note that the structure in which the air gap in FIG. 5 is filled with the composite magnetic material may be used.

The composite magnetic bobbin and the second magnetic body may be fixed by an arbitrary method such as an adhesive or a tape from the outside. The point that such an assembling process is necessary is that, after winding a coil around a conventional magnetic material, filling the coil portion with a paste made of a magnetic material and a resin,
This embodiment is disadvantageous in some aspects as compared with a method of integrally forming a similar structure by curing a resin. However, in the method of integrally manufacturing, the characteristics of the obtained element vary greatly due to curing shrinkage of the resin at the time of integration, displacement of the built-in coil, or variation in the amount of paste, etc. As a result, it is difficult to fine-tune the characteristics later, and there is a problem that if the deviation of the characteristics is extremely large, the whole must be discarded.

On the other hand, in this embodiment, the composite magnetic bobbin is first manufactured and then combined with the second magnetic body, so that the size and the like of the second magnetic body and the gap width to be inserted are adjusted. By the method, the characteristics can be fine-tuned, and even if there is an extremely large deviation in the characteristics, only the portion of the composite magnetic bobbin needs to be discarded. As a result, the yield is improved and the cost is reduced. There is an advantage.

In the case where the second magnetic body is manufactured integrally, when the thin second magnetic body is used in order to manufacture a small-sized one, the second magnetic body may be cracked due to shrinkage stress when the resin is cured. Also, if a high pressure is applied to increase the filling ratio of the magnetic material in the composite portion to improve the characteristics, it is inevitable that a pressure is applied to the second magnetic material. Cracks or cracks occur, deteriorating the characteristics. Regarding these points, in the present embodiment, even if the shrinkage stress at the time of curing the resin and the filling rate of the magnetic material in the composite portion is increased by applying a high pressure, a force is not applied to the second magnetic material. Thus, it is possible to obtain a high-performance magnetic element without breaking the second magnetic body.

The structures shown in FIGS. 3, 4 and 5 show only some examples of the embodiment of the present invention, and the present invention is not limited to these embodiments. Even if the shape or winding method or the arrangement of the second magnetic body changes,
Even if a transformer requires a secondary winding, the effect can be obtained without any problem if the requirements of the present invention are satisfied.

[0037]

Embodiments of the present invention will be described below. In addition,
In the embodiment, the case where a thermosetting epoxy resin is used as the resin is shown. However, as described above, almost the same results can be obtained with other resins.

Example 1 As magnetic metal powder, 93% Fe-3.5% Si-3.5% C having an average particle size of about 15 μm was used.
r powder was prepared. After adding 2% by weight of talc powder to the metal magnetic powder and mixing, 3.5% by weight of epoxy resin was added and mixed well, and the mixture was granulated through a mesh. Next, using a 1 mm diameter coated copper wire, the inner diameter was 5.5.
A 2.5-turn coil having a 2-mm stack length of 2.5 mm was prepared. Part of the granulated powder is placed in a mold with a 12.5 mm square, 4.5 mm square cylinder at the center, pressed lightly, and then the coil is inserted so that it fits in the center cylinder. And press-formed at a pressure of 3.5 t / cm ² . after that,
After removing from the mold, the epoxy resin was cured by heating at 160 ° C. for 1 hour to obtain a composite bobbin with a built-in coil having a structure shown in FIG. The outer size of the obtained bobbin was 12.5 × 12.5 × 2.2 mm, and the filling rate of the metal powder was 73% by volume.

Next, 50% Fe-50% having a particle size of 20 μm.
1 weight percent of silicon resin is added to Ni powder,
After molding at 0 t / cm ² , it was annealed in nitrogen to produce a 12.5 × 12.5 ×
A dust core having a column having a diameter of 1.0 mm and a diameter of 4.3 mm at the center was prepared. By combining the dust core with the composite bobbin with a built-in coil, a magnetic element having a structure shown in FIG. 4 and having a size of 12.5 × 12.5 × 4.2 mm was manufactured. The inductance of this magnetic element is 0A
And 20A, 2.5 μH, 1.
It was as large as 8 μH and the current value dependence was small. The electric resistance of the coil conductor was 3.0 mΩ. For comparison, insert the dust core into a 12.5 mm square mold,
A small amount of the granulated powder described above, a coil, a granulated powder, and a dust core were placed on top of it, and an attempt was made to mold the whole unit. It was impossible.

Example 2 A MnZn ferrite powder having an average particle size of about 1 μm was prepared as a magnetic powder. 20% by weight of an epoxy resin was added to this powder and mixed well to form a paste. In addition, a transformer coil having 12 turns on the primary side and 24 turns on the secondary side was prepared using a coated conductor having a diameter of 0.2 mm. Using the paste and the coil, the outer size is 8 × by the transfer molding method.
A composite magnetic bobbin having a size of 8 × 1.6 mm, a through hole having a diameter of 3.1 mm at the center, and a built-in coil was produced. Next, the sheet thickness is 0.7 mm and the outer size is 8 × 8.
mm, there was a magnetic leg at the center, and the diameter of the magnetic leg was 3 mm, and the total thickness of the central magnetic leg was 1.5 mm. From the core and the magnetic bobbin, a transformer having an outer shape of 8 × 8 × 3 mm was produced. 2 for comparison
Using a number of MnZn ferrite cores,
A 3 mm square drum core was prepared, and the same winding was applied to this core.
A sample having almost the same structure was prepared by filling the winding portion and curing the resin by heating. In addition, a similar sample was prepared using a plastic bobbin without a built-in coil, but the bobbin portion wasted space. Turns, secondary side 18 turns, outer shape 11.5 × 8 × 3
mm.

When these three types of transformers were compared with each other, cracks were observed in the ferrite when the rectangular drum core was wound and then filled with the above-mentioned ferrite-containing paste. This is presumably because the ferrite had a small thickness of 0.7 mm, and was stressed due to shrinkage during curing of the resin and cracked. In the case of using a normal plastic bobbin, the inductance value on the primary side / secondary side is 15 μH / 60 μH, and the DC superimposed current is 1 A.
When flowing, the drop was considerably reduced to 14 μH / 42 μH on the secondary side having 18 turns. On the other hand, in the case of the present invention, no crack was observed, the primary side / secondary side inductance value was as large as 22 μH / 88 μH, and the size was 21 μH / 73 μH even when the superimposed DC current was applied at 1 A. Despite its small size and large number of turns, it did not change much.

[0042]

According to the structure of the magnetic element of the present invention, a coil bobbin, which was conventionally a wasteful space in terms of characteristics, becomes a magnetic composite and has a large magnetic path cross-sectional area, so that a small, high-performance magnetic element can be obtained. Can be In addition, variations in characteristics at the time of manufacturing can be reduced, and characteristics can be easily adjusted after manufacturing.

Further, when the metal magnetic powder is used as the composite magnetic material, there is no fear that the second magnetic material is damaged even if the filling ratio is high by high-pressure molding, so that the characteristics can be further improved. It is.

As described above, the present invention is excellent as a magnetic element such as an inductor, a choke coil, and a transformer used for various electronic devices, and has great industrial value.

[Brief description of the drawings]

FIG. 1A is a perspective view of a composite magnetic bobbin with a built-in coil (when the magnetic bobbin does not have a hole) according to an embodiment of the present invention. FIG. Cross section with line

FIG. 2A is a perspective view of a composite magnetic bobbin having a built-in coil (when the magnetic bobbin has a circular through hole as a hole) in the embodiment of the present invention. Sectional view along line AA '

3A is a perspective view of a magnetic element according to an embodiment of the present invention manufactured using the composite magnetic bobbin shown in FIG. 1, and FIG. 3B is a sectional view taken along line AA ′ in FIG. Sectional view

4A is a perspective view of a magnetic element according to an embodiment of the present invention manufactured using the composite magnetic bobbin shown in FIG. 2; FIG. 4B is a perspective view taken along line AA ′ of FIG. Sectional view

5A is a perspective view of a magnetic element according to another embodiment of the present invention manufactured using the composite magnetic bobbin shown in FIG. 2, and FIG. 5B is an AA ′ line of FIG. Cross section at

[Explanation of symbols]

 Reference Signs List 11 coil 12 composite magnetic material 13 terminal electrode 14 hole 15 second magnetic material 16 mating surface 17 air gap

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinya Matsutani 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. Terms (reference) 5E044 BA01 5E062 FF02 5E070 AA01 AA11 AB02 BA11 BB03 CA12 DA13

Claims (12)

[Claims] 1. A magnetic element, comprising: a bobbin including at least a magnetic powder, an organic resin, and a coil, and including a coil, and a second magnetic body in contact with the bobbin. 2. A bobbin including at least a magnetic powder, an organic resin, and a coil and having a hole therein with the coil incorporated therein, and a second magnetic body having at least a part thereof inserted into the hole of the bobbin. The magnetic element according to claim 1, comprising: 3. The magnetic element according to claim 1, wherein a gap is formed in the magnetic circuit made of the second magnetic material. 4. The magnetic element according to claim 2, wherein a gap is formed in the magnetic circuit made of the second magnetic material, and the gap is located in a hole of a bobbin containing the coil. . 5. The method according to claim 1, wherein the magnetic powder constituting the bobbin is ferrite.
Item 7. A magnetic element according to item 1. 6. The method according to claim 1, wherein the magnetic powder forming the bobbin is a metal magnetic material.
Item 7. A magnetic element according to item 1. 7. The magnetic element according to claim 5, wherein the bobbin further contains one or more kinds of insulating substances. 8. The magnetic element according to claim 7, wherein said insulating substance is a solid powder. 9. The solid powder of one or more selected from boron nitride, talc, mica, zinc oxide, titanium oxide, silicon oxide, aluminum oxide, iron oxide, barium sulfate, fluororesin, and stearate. 9. The magnetic element according to claim 8, wherein: 10. The magnetic element according to claim 6, wherein the magnetic material filling ratio of the bobbin is 70% by volume or more and 90% by volume or less. 11. A mixing step of mixing an organic resin with at least a magnetic powder, and forming the mixture obtained in the mixing step into a bobbin having a predetermined shape while incorporating a coil by an injection molding method or a transfer molding method. A method for manufacturing a magnetic element, comprising: a step of combining the bobbin with a second magnetic body. 12. At least a mixing step of mixing an organic resin with the magnetic powder, a step of sieving the mixture obtained in the mixing step into granules, and incorporating a coil into the granules with a mold. Press-forming a bobbin of a predetermined shape while
Combining the bobbin and a second magnetic body.