JP2002141230A - Thin core and inductive device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively provide a thin core having a high saturated magnetic flux density, a proper frequency characteristics, and a superior mechanical strength. SOLUTION: This thin core is constituted by alternately laminating a plurality of soft magnetic metallic films 2 and a plurality of layers of a composite magnetic material 3, prepared by uniting magnetic material powder by using resin as a binder upon another and integrating the laminate. The material, used for forming the films 2, includes a crystalline iron- or cobalt-based soft magnetic alloy, microcrystalline iron- or cobalt-based soft magnetic alloy, pure iron, ferrosilicon, etc. The soft magnetic material power includes the powder of pure iron, ferrosilicon, ferro-aluminum, iron-nickel alloy, carbonyl iron, a monocrystalline spherical metal magnetic material coated for insulation, etc., and the monocrystalline powder of an oxide-based magnetic material, such as ferrite, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin core using a composite magnetic material and an inductive device such as a coil, a common mode choke coil, a transformer, and a coil for a flat motor using the same. TECHNICAL FIELD The present invention relates to a thin core that can also secure an objective strength and an inductive device using the same.

[0002]

2. Description of the Related Art As a conventional thin core, there has been one constituted by the following technology.

(1) As shown in FIG. 6, a nonmagnetic insulating layer or an adhesive is formed on the surface of a thin metal magnetic film 41 such as an amorphous magnetic alloy (amorphous) or a microcrystalline magnetic alloy (trade name: Finemet). The layer 42 is formed, and a plurality of layers are laminated.

(2) As shown in FIG. 7, a resin-based composite magnetic material is used (JP-A-4-58753, JP-A-7-2
No. 35410).

(3) As shown in FIG. 7, a thin core is made of ferrite.

(4) As shown in FIG. 7, a dust core made of a metallic magnetic material is used.

[0007]

The thin cores constructed by the techniques (1) to (4) have the following disadvantages.

[0008] Regarding (1), the production process is complicated, expensive, and its use is limited. The frequency characteristics are good as compared with the case where a bulk metal magnetic material is used, but are significantly inferior as compared with ferrite or the like. The usable frequency is usually 10 kHz or less.

Regarding (2), although the frequency characteristics are good, the saturation magnetic flux density is small. Increasing the density using metal-based magnetic material powder increases the saturation magnetic flux density, but this time the strength is reduced, making it difficult to make the core thinner

Regarding (3), the frequency characteristics are good, but the saturation magnetic flux density is small and the core is thick. It is easy to crack when thinned.

Regarding (4), since there is basically conduction between the magnetic material powders, the frequency characteristics are poor. Since the temperature is increased during sintering, dimensional accuracy is poor.

[0012] A first object of the present invention is to solve the above problems,
An object of the present invention is to provide a low-cost core having a high saturation magnetic flux density, good frequency characteristics, and excellent mechanical strength.

A second object of the present invention is to provide an inductive device, such as a thin coil having excellent frequency characteristics and mechanical strength, a common mode choke coil, a transformer, and a coil for a flat motor, by using the above thin core. Is to provide.

Other objects and novel features of the present invention will be clarified in embodiments described later.

[0015]

In order to achieve the above object, a thin core according to the invention of claim 1 of the present application comprises one or both of a metal soft magnetic film and a metal soft magnetic fiber cloth. And a composite magnetic body formed by combining a magnetic material powder with a resin as a binder.

The thin core according to the invention of claim 2 of the present invention is the thin core according to claim 1, wherein the magnetic material powder in the composite magnetic material is a metal-based magnetic material powder, an insulating-coated spherical single-crystal metal magnetic material powder or an oxide-based magnetic material powder. It is a single crystal powder of a magnetic material.

According to a third aspect of the present invention, there is provided the thin core according to the first or second aspect, wherein the ratio of the magnetic material powder in the composite magnetic body is 70% by weight or more.

An inductive device according to the invention of claim 4 of the present application is formed by combining one or both of a metal-based soft magnetic film and a cloth of a metal-based soft magnetic fiber with a magnetic material powder using a resin as a binder. It is characterized by comprising a thin core in which a composite magnetic material is laminated and integrated, and a coil conductor.

According to a fifth aspect of the present invention, in the inductive device according to the fourth aspect, on the composite magnetic body,
The coil conductor is characterized by forming one or more conductor layers.

According to a sixth aspect of the present invention, in the inductive device according to the fourth or fifth aspect, a plurality of the coil conductors are provided so as to be electromagnetically coupled to each other.

According to a seventh aspect of the present invention, in the inductive device according to the fourth or fifth aspect, the thin core constitutes a stator yoke of a flat motor, and the coil conductor constitutes a stator coil. Features.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a thin core according to the present invention and an inductive device using the same will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention, in which a thin core is formed. As shown in this figure,
The thin core 1 is composed of a metal-based soft magnetic film 2 and a composite magnetic material 3 formed by combining magnetic material powder with a resin as a binder.
Are laminated and integrated in layers.

The metal-based soft magnetic film 2 includes:
Films such as iron-based or cobalt-based amorphous soft magnetic alloys (amorphous), iron-based or cobalt-based microcrystalline soft magnetic alloys (trade name: Finemet), pure iron, silicon iron, and the like can be given.

It is preferable that the thickness of the metal-based soft magnetic film 2 is as small as possible as long as the mechanical strength can be guaranteed. The thickness is more advantageous when only the mechanical strength is considered, but the frequency characteristics of the eddy current loss deteriorate in inverse proportion to the square of the thickness.

The composite magnetic body 3 is prepared by compression molding by mixing a soft magnetic material powder and a resin binder. The composite magnetic body 3 is subjected to compression molding with the metal-based soft magnetic film 2 stacked. Thereby, lamination and integration can be performed so as to be mutually layered.

Examples of the soft magnetic material powder include pure iron, iron silicon, iron aluminum, iron nickel alloy, carbonyl iron, and CSC (Coated Single Crystal). , And a single crystal powder of an oxide-based magnetic material such as ferrite.

In the composite magnetic body 3, it is preferable to use a metal-based soft magnetic material powder as the soft magnetic material powder because the saturation magnetic flux density is high. Use of CSC powder is preferable because the saturation magnetic flux density is improved, the loss of the magnetic material is reduced, and the insulation resistance at the grain boundaries is significantly improved, so that the frequency characteristics are improved. Further, the use of a single crystal of an oxide-based magnetic material is preferable because the insulation resistance is the highest and the loss of the magnetic material is smaller than that of a polycrystalline material.

As the resin binder for molding the soft magnetic material powder, epoxy, polyimide, liquid crystal polymer and the like are preferable, but the content of the binder must be as low as possible. The powder is 70% by weight or more and the resin binder is 30% by weight or less. If the soft magnetic material powder is less than 70% by weight, the magnetic properties are significantly reduced, which is not preferable. If possible, the content of the resin binder is more preferably 2% by weight or less.

The resin material used as the binder preferably has no filler in order to increase the filling ratio of the soft magnetic material powder. Further, it is preferable that the viscosity is as low as possible.

According to the thin core described in the first embodiment, the following effects can be obtained.

(1) In general, the saturation magnetic flux density of a magnetic core is proportional to the density of a magnetic material. Therefore, in order to improve the saturation magnetic flux density, it is necessary to increase the density. Drops and breaks easily. In order to compensate for this, in the present embodiment, the metal-based soft magnetic film 2 is used as a strength member. Although a structure using a non-magnetic strength member such as glass cloth or polyimide is also conceivable, in this case, the effective saturation magnetic flux density decreases. When a metal-based soft magnetic film is used, the saturation magnetic flux density of the film itself is large, so that the effective saturation magnetic flux density does not decrease. Also,
Since the film has appropriate flexibility, it can be combined with the composite magnetic material 3 which is a plastic material to enhance the mutual goodness like a reinforced concrete and to have a structure having good mechanical strength characteristics. .

(2) In the composite magnetic body 3, by using a resin as a binder, the processing temperature is greatly reduced as compared with the dust core, so that the dimensional accuracy of the core is improved. Further, since the soft magnetic material particles do not sinter, the insulation resistance at the grain boundaries increases, and the frequency characteristics are improved.

In the first embodiment, the metal soft magnetic material film is laminated with the composite magnetic material. However, instead of the film, a cloth material woven with the same metal soft magnetic material fiber is used. (Such as a cross). In this case, improvement in flexibility and improvement in frequency characteristics can be expected. The diameter of the fiber is, for example, 5 to 20 μm.

FIGS. 2 and 3 show a second embodiment of the present invention, in which one or both of a metal soft magnetic film and a metal soft magnetic fiber cloth and a resin are used as a binder. 1 shows a coil as an inductive device using a thin core obtained by laminating and integrating a composite magnetic material.

In these figures, reference numeral 11 denotes a lower thin core, and a composite magnetic material 13 using a resin as a binder is provided on one side of a metal-based soft magnetic film (or a cloth of a metal-based soft magnetic fiber) 12. The layers are laminated and integrated, and the material is as described in the first embodiment. The composite magnetic body 13 has a center pole portion 13a and an outer peripheral portion 13b.
Or another composite magnetic body is integrated as the center pole portion 13a and the outer peripheral portion 13b.

An insulating layer 14 made of epoxy resin is formed on the composite magnetic body 13, and two spiral first and second coil conductor layers 15 and 16 are further formed on the insulating layer 14 in FIG.
It is formed as shown in FIGS. However, an epoxy resin interlayer insulating layer 17 is provided between the coil conductor layers 15 and 16, and the coil conductor layers 15 and 16 are interconnected by via holes 18 to form a coil conductor 20. One end of the coil conductor 20 is connected to an external electrode 25a formed on the outer peripheral portion of the lower thin core 11, and the other end is connected to the external electrode 25b.

When the coil conductor 20 is formed on the composite magnetic body 13, the composite magnetic body 13 has a lower magnetic permeability than the metal soft magnetic film 12 such as an amorphous soft magnetic alloy. The layer 13 is preferable because it has an appropriate magnetic resistance and magnetic flux is prevented from being concentrated on the metal-based soft magnetic film 12.

After the formation of the coil conductor 20, the external electrodes 2
The upper thin core 19 having the shape as shown in FIG.
3b is bonded and integrated (adhered) to the upper end surface. The upper thin core 19 is the same as the lower thin core 11 except that there is no center pole portion and no outer peripheral portion.

According to the second embodiment, by forming the first and second coil conductor layers 15 and 16 on the thin core 11, a thin coil having good mechanical strength can be manufactured. In addition, since the thin core 11 has good frequency characteristics and a high saturation magnetic flux density, it is possible to realize a high-performance thin coil with good frequency characteristics and low magnetic saturation.

The method of forming the coil conductor is preferably a method other than the winding of a wire. This is because it is desired to make the entire coil thin. The following are examples of the construction method.

(1) A coil conductor portion prepared by a normal printed multilayer board construction method (such as a subtractive construction method) is attached to a thin core composite magnetic body. (2) Form a coil conductor layer directly on the composite magnetic body with a thin core by the build-up method. (3) The coil conductor layer is formed by the pattern plating method in the above (2). That is, a method of forming a resist wall on both sides of the conductor pattern and performing a plating process is adopted. (4) HAP method (high aspect method) in which plating is isotropic in (2) above. For example, JP-A-11-204
No. 337, and JP-A-11-204361, in which a pattern of a plating underlayer is formed by a photolithography technique, and then a mushroom-shaped plating layer in section is expanded. (5) A pattern in which both sides of a thin core are patterned by the HAP method. (6) HAP pattern laminated by build-up method.

It is preferable that the coil conductor portion is made of a high aspect conductor, because the space factor is improved, the thickness of the coil conductor portion can be suppressed, and the height of the entire inductive device can be suppressed.

In the second embodiment, one coil conductor 20 is manufactured by connecting the coil conductor layers 15 and 16 of each layer with a via hole. However, a plurality of coil conductors are provided so as to be electromagnetically coupled to each other. Thus, it is clear that a thin transformer and a common mode choke coil can be configured.

FIG. 4 shows a third embodiment of the present invention, in which one or both of a metal soft magnetic film and a metal soft magnetic fiber cloth, and a composite magnetic material using a resin as a binder. 2 shows a coil as an inductive device using a thin core obtained by laminating and integrating the above. In this figure, reference numeral 21 denotes a lower thin core, which is a metallic soft magnetic film (or a metallic soft magnetic fiber cloth) 12
The composite magnetic body 13 using a resin as a binder is laminated and integrated on both sides in a layered manner, and the material is as described in the first embodiment. The composite magnetic body 13 on one side has a center pole portion 13a and an outer peripheral portion 13b integrally, or another composite magnetic body has a center pole portion 13a.
And the outer peripheral portion 13b. The upper thin core 29 has the same configuration (however, the center pole portion and the outer peripheral portion are not required).

The other structure, operation and effect are the same as those of the second embodiment, and the same or corresponding portions are denoted by the same reference characters and description thereof is omitted.

FIG. 5 shows a fourth embodiment of the present invention.
In this case, as an inductive device using a thin core formed by laminating and integrating one or both of a metal-based soft magnetic film and a cloth of a metal-based soft magnetic fiber and a composite magnetic material using a resin as a binder, the flat device is flat. The example which comprised the coil device (stator) for motors is shown. Here, the thin core 31 constituting the stator yoke is made of a metal-based soft magnetic film (or a cloth of a metal-based soft magnetic fiber) 3.
2, a composite magnetic body 33 using a resin as a binder is laminated and integrated in layers, and the material is as described in the first embodiment. The composite magnetic body 33 has center pole portions 33a at equal angular intervals around the shaft 43.
Or another composite magnetic body is integrated as the center pole portion 33a. A stator coil (armature coil) 40 formed by laminating a plurality of coil conductor layers is provided around each center pole portion 33a.

The non-magnetic or magnetic housing portion 42 of the ball bearing 41 is fixed to the thin core 31, and the ball bearing 4
The shaft 43 is rotatably supported inside 1. A rotor yoke 44 is fixed to one end of the shaft 43 and a hub 45 is fixed to the other end, respectively.
The rotor permanent magnet 50 is fixed to the rotor 4, and the rotor rotates to face the stator. These constitute a brushless DC motor.

According to the fourth embodiment, the overall structure is simple and thin, and the eddy current loss is almost suppressed, so that a highly efficient thin motor can be constructed. In this case, the stator coil is built up directly on the stator yoke,
It is preferable to use the P method.

[0050]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a thin core according to the present invention and an inductive device using the same will be described in detail with reference to embodiments.

Example 1 An anneal-processed amorphous soft magnetic alloy film having a thickness of 20 μm was formed to a thickness of 0.2 mm by mixing carbonyl iron powder with 2% by weight of an epoxy resin as a binder.
By hot pressing, a thin I-core formed by laminating a composite magnetic material on an amorphous soft magnetic alloy film was formed. On this, an insulating layer having a thickness of 10 μm was formed with epoxy resin, and further, two spiral coil conductor layers were formed thereon.
The state at this time is shown in FIGS. The cross-sectional shape of the spiral conductor layer is 120 μm in height and 90 μm in width.
m, and the conductor spacing is 10 μm. The interlayer insulating layer is epoxy resin, the thickness is 10 μm, and the diameter of the via hole is 50 μm.
m. The center pole and the outer periphery were filled with carbonyl iron powder mixed with 5% by weight of epoxy resin, and then an upper core as shown in FIG. 2 (C) was adhered. The material of the upper core is the same as that of the lower core, and the amorphous magnetic alloy film side is the upper side (outer side).

The outer shape of the coil thus constructed was 3.5 × 3.5 × 0.8 mm in thickness and showed good characteristics.

Although the embodiments of the present invention have been described above, it is obvious to those skilled in the art that the present invention is not limited to the embodiments and various modifications and changes can be made within the scope of the claims. There will be.

[0054]

As described above, according to the present invention,
A thin core having excellent saturation magnetic flux density and frequency characteristics, excellent in mechanical strength, and an inductive device using the same can be realized at low cost.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a thin core according to a first embodiment of the present invention.

FIG. 2 is a plan view showing a coil as an inductive device using a thin core according to a second embodiment of the present invention.

FIG. 3 is a sectional view taken along the line III-III of FIG. 2;

FIG. 4 is a side sectional view showing a coil according to a third embodiment of the present invention.

FIG. 5 is a side sectional view of a flat motor coil device as an inductive device using a thin core according to a fourth embodiment of the present invention.

FIG. 6 is a side sectional view showing one example of a conventional magnetic core.

FIG. 7 is a side sectional view showing another example of a conventional magnetic core.

[Explanation of symbols]

 1, 11, 19, 21, 29, 31 Thin core 2, 12, 32 Metal-based soft magnetic film 3, 13, 33 Composite magnetic body 14, 17 Insulating layer 15, 16 Coil conductor layer 20 Coil conductor 25a, 25b External Electrode 40 Stator coil 50 Permanent magnet

Claims (7)

[Claims] 1. One or both of a metal-based soft magnetic film and a metal-based soft magnetic fiber cloth and a composite magnetic body obtained by bonding a magnetic material powder with a resin as a binder are laminated and integrated. Characterized by a thin core. 2. The magnetic material powder in the composite magnetic body,
The thin core according to claim 1, wherein the core is a metal-based magnetic material powder, an insulating-coated spherical single-crystal metal-based magnetic material powder, or an oxide-based magnetic material single-crystal powder. 3. The thin core according to claim 1, wherein the ratio of the magnetic material powder in the composite magnetic body is 70% by weight or more. 4. A thin type in which one or both of a metal soft magnetic film and a metal soft magnetic fiber cloth and a composite magnetic material obtained by binding a magnetic material powder with a resin as a binder are laminated and integrated. An inductive device comprising a core and a coil conductor. 5. The coil conductor is formed by forming one or more conductor layers on the composite magnetic body.
The inductive device as described. 6. The inductive device according to claim 4, wherein a plurality of said coil conductors are provided so as to be electromagnetically coupled to each other. 7. The inductive device according to claim 4, wherein the thin core forms a stator yoke of a flat motor, and the coil conductor forms a stator coil.