JP7059594B2 - Soft magnetic materials, cores and inductors - Google Patents

Description

The present invention relates to soft magnetic materials, cores and inductors.

In recent years, along with the high-density mounting and high-speed processing of electronic devices, there is a demand for smaller and higher output inductors, and this miniaturization has increased the volume of the inductor core (core made of magnetic material). Since it decreases, it tends to cause a decrease in inductance and deterioration of DC superimposition characteristics (inductance at the time of DC current load).

Therefore, there is a demand for a core that does not cause a decrease in inductance and deterioration of DC superimposition characteristics even when the size is reduced, that is, a soft magnetic material having high magnetic permeability and excellent DC superimposition characteristics.

As inventions relating to conventional soft magnetic materials, for example, the soft magnetic materials, cores and inductors described in Patent Document 1 are known. The soft magnetic material is an insulating coating of a first soft magnetic metal powder having a particle size of 20 μm or more and 50 μm or less, a second soft magnetic metal powder having a particle size of 1 μm or more and 10 μm or less, and a resin. It is a soft magnetic material containing. The ratio of the mass% of the first soft magnetic metal powder to the mass% of the second soft magnetic metal powder is A: B, and A + B = 100, 15 ≦ A ≦ 35 and 65 ≦ B ≦. 85.

Japanese Unexamined Patent Publication No. 2014-204108

In the technique of Patent Document 1, the ratio of the second soft magnetic metal powder having a particle size of 1 μm or more and 10 μm or less, which is a fine powder, is higher than that of the first soft magnetic metal powder having a particle size of 20 μm or more and 50 μm or less, which is a coarse powder. Due to the large configuration, the filling rate of the soft magnetic material cannot be sufficiently increased. When the core was produced with the same configuration as in Patent Document 1, the magnetic permeability was small, and it was insufficient to obtain a high magnetic permeability and good DC superimposition characteristics that could meet the recent demand for miniaturization.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a soft magnetic material, a core, and an inductor having high magnetic permeability and excellent DC superimposition characteristics.

The soft magnetic material of the present invention contains a soft magnetic metal powder and a resin, and the soft magnetic metal powder is composed of a particle group α and a particle group β, the peak intensity of the particle group α is IA, and the volume of the particle group α. Is Vα, the peak intensity of the particle group β is IB, the volume of the particle group β is Vβ, and the minimum intensity existing between the particle group α and the particle group β is IC, the intensity ratio IC / IA is 0. It is characterized by having a volume ratio of .12 or less and a volume ratio of Vα / Vβ of 2.0 or more and 5.1 or less. However, in the particle size distribution of the soft magnetic metal powder, the particle group α is a particle group containing the maximum peak intensity, and the peak particle size PA of the particle group α is larger than the peak particle size PB of the particle group β. .. Further, when the peak intensities of the particle group α are set to IA1, IA2, ..., IAx (x is 1 or more) in descending order, the peak intensity IA of the particle group α is set to IA1 and the peak particle size PA of the particle group α is set. Let it be PA1. Further, when the peak intensities of the particle group β are set to IB1, IB2, ..., IBy (y is 1 or more) in descending order, the peak intensity IB of the particle group β is set to IB1 and the peak particle size PB of the particle group β is set. Let it be PB1.

That is, there are few particles having an intermediate particle size between the particle group α and the particle group β. Therefore, the small particle size particles of the particle group β can be efficiently filled in the voids formed between the large particle size particles of the particle group α. In addition, the filling rate of the soft magnetic particles in which the particle group α and the particle group β are combined can be increased. As a result, it is presumed that high magnetic permeability and good DC superimposition characteristics could be obtained. However, the action is not limited to this.

The peak particle size PA of the particle group α is preferably 60 μm or less. Within this range, it is presumed that the DC superimposition characteristic is improved, the distribution state of the resin portion and the void portion becomes a structure state in which segregation is difficult to occur, and the structure in the sample becomes uniform. However, the action is not limited to this.

The soft magnetic metal powder constituting the particle group α is a metal containing Fe or Fe, and is preferably coated with an insulating material. By using Fe or a metal containing Fe having a high saturation magnetization, there is a tendency that the magnetic permeability is high and the DC superimposition characteristic is good. Further, by covering with an insulating material, the DC superimposition characteristic tends to be improved. The coating referred to here means covering a part or all of the particles.

The core according to one embodiment of the present invention is characterized in that it is made of the soft magnetic material.

The inductor according to one embodiment of the present invention is characterized by including the core.

According to the present invention, it is possible to provide a soft magnetic material, a core and an inductor having high magnetic permeability and excellent DC superimposition characteristics.

The figure which shows the particle size distribution (frequency distribution) of the soft magnetic material of Example 5. The figure which shows the particle size distribution (frequency distribution) of the soft magnetic material of Example 15. The figure which shows the particle size distribution (frequency distribution) of the soft magnetic material of the comparative example 1. The figure which shows the particle size distribution (frequency distribution) of the soft magnetic material of the comparative example 3. It is a conceptual diagram for demonstrating the internal structure of a thin film inductor. It is a conceptual diagram for demonstrating the appearance of a thin film inductor.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments. Further, the components in the following embodiments include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those that are in a so-called equal range.

The soft magnetic material of the embodiment contains a soft magnetic metal powder and a resin, and the soft magnetic metal powder is composed of a particle group α and a particle group β, and has a peak intensity of the particle group α of IA and a volume of the particle group α. When Vα, the peak intensity of the particle group β is IB, the volume of the particle group β is Vβ, and the minimum intensity existing between the particle group α and the particle group β is IC, the intensity ratio IC / IA is 0. It is characterized in that the volume ratio Vα / Vβ is 12 or less and the volume ratio is 2.0 or more and 5.1 or less. However, in the particle size distribution of the soft magnetic metal powder, the particle group α is a particle group containing the maximum peak intensity, and the peak particle size PA of the particle group α is larger than the peak particle size PB of the particle group β. .. Further, when the peak intensities of the particle group α are set to IA1, IA2, ..., IAx (x is 1 or more) in descending order, the peak intensity IA of the particle group α is set to IA1 and the peak particle size PA of the particle group α is set. Let it be PA1. Further, when the peak intensities of the particle group β are set to IB1, IB2, ..., IBy (y is 1 or more) in descending order, the peak intensity IB of the particle group β is set to IB1 and the peak particle size PB of the particle group β is set. Let it be PB1. Then, the point having the minimum intensity IC existing between the particle group α and the particle group β is defined as C, and the particle size thereof is defined as PC.

Peaks A1, A2, ..., Ax (x is 1 or more), B1, B2, ..., By (y is 1 or more), and point C are obtained by measurement by, for example, a laser diffraction / scattering method. It can be determined from the volume-based particle size distribution, and the peak particle sizes PA1, PA2, ..., PAx (x is 1 or more), PB1, PB2, ..., PBy (y is 1) from the peaks and points. IA1, IA2, ..., IAx (x is 1 or more), IB1, IB2, ..., IBy (y is 1 or more), particle size PC at point C, and strength IC can be calculated. .. Further, in the volume-based particle size distribution, the volume Vα of the particle group α and the volume Vβ of the particle group β can be calculated by setting the particle group α on the large particle size side and the particle group β on the small particle size side from the PC.

FIG. 1 is an example of a particle size distribution showing a typical embodiment of the present invention. In FIG. 1, Vα / Vβ is 2.0 or more and 5.1 or less, and the voids formed between the large particle size particles of the particle group α are efficiently filled with the small particle size particles of the particle group β. It is possible to increase the filling rate of the soft magnetic particles in which the particle group α and the particle group β are combined. When the intensity ratio IC / IA is larger than 0.12 as shown in FIG. 2, particles having an intermediate size between the particle group α and the particle group β increase, so that a high filling rate cannot be obtained. Further, when the volume ratio Vα / Vβ is larger than 5.1, the small particle size particles of the particle group β are insufficient and voids are likely to be formed, and when the volume ratio Vα / Vβ is smaller than 2.0, the particle group It is presumed that the small particle size particles of β become excessive and these particles cause a decrease in the filling rate.

The intensity ratio IC / IA is more preferably 0.008 or more and 0.08 or less, and further preferably 0.01 or more and 0.06 or less. When the strength ratio IC / IA is small, a high filling rate tends to be obtained, but when it is 0.003 or less, a decrease in the filling rate is seen.

The volume ratio Vα / Vβ is preferably 2.5 or more and 4.4 or less, and more preferably 3.0 or more and 4.0 or less. With such a configuration, the filling rate is high, and there is a tendency that deterioration of the special current superimposition characteristic can be suppressed.

The peak particle size PA of the particle group α is preferably 60 μm or less, and the DC superimposition characteristic tends to deteriorate as the peak particle size PA increases, and the magnetic permeability tends to decrease as the peak particle size PA decreases. Be done. From the viewpoint of magnetic permeability and DC superimposition characteristics, the peak particle size PA of the particle group α is more preferably 10 to 60 μm, still more preferably 15 to 60 μm. The peak particle size of the powder used in the particle group α can be adjusted by removing coarse particles and fine powder by classification.

As the particles of the particle group α, particles produced by an atomizing method such as a water atomizing method or a gas atomizing method can be used. Generally, it is easier to obtain particles with a high circularity when the gas atomizing method is used, but even when the water atomizing method is used, particles with a high circularity can be obtained by appropriately adjusting the spraying conditions and the like.

The soft magnetic metal powder constituting the particle group α is preferably Fe or a metal containing Fe (including an alloy), and the surface is preferably coated with an insulating material. Examples of the Fe-containing metal include Fe-B-Si-Cr-based, Fe-Si-Cr-based, Fe-Ni-Si-Co-based, and Fe-Si-B-Nb-Cu-based amorphous alloys. .. In addition, as the insulating coating material, a compound containing one or more kinds selected from phosphate glass, MgO, CaO and ZnO, an aqueous solution containing boric acid or an aqueous dispersion and a mixed boron compound, and titanium alkoxides are used. Any coating material such as formed titanium oxide and silicon oxide can be selected.

Further, the soft magnetic metal powder constituting the particle group α may be used by mixing a plurality of metal particles. For example, particles made of Fe and particles made of Fe—B—Si—Cr-based amorphous alloy whose surface is insulated and coated with a boron compound can be mixed and used.

The peak particle size PB of the particle group β is preferably 0.5 μm to 5 μm, more preferably 0.7 μm to 4 μm, and even more preferably 0.7 μm to 2 μm from the viewpoint of improving the filling rate of the soft magnetic metal particles. preferable. The peak particle size of the powder used for the particle group β can be set to a desired peak particle size by removing coarse particles and fine powder by classification and adjusting the particle size distribution.

The particles of the particle group β are particles produced by an atomization method such as a water atomization method or a gas atomization method, particles of several μm produced by the carbonyl method, and submicrons prepared by a spray pyrolysis method, as in the particle group α. Particles and the like can be used.

As the soft magnetic metal powder constituting the particle group β, a metal (including an alloy) containing Fe or Fe can be used, and the composition may be different from that of the particle group α. Examples of the metal containing Fe include Fe—Ni based alloys. As for the particle group β, particles whose surface is covered with an insulating material can be used as in the case of the above-mentioned particle group α. As the insulating coating material, any coating material such as the above-mentioned material can be selected.

Further, the soft magnetic metal powder constituting the particle group β may be used by mixing a plurality of metal particles in the same manner as in the above-mentioned particle group α.

In the soft magnetic material of the present embodiment, the insulating property between the soft magnetic particles is maintained by the resin, but by using the powder obtained by applying the insulating treatment to the particle surface of the soft magnetic particles themselves, the insulating property is further improved. Excellent DC superimposition characteristics can be obtained, and even more preferable insulating properties, withstand voltage and DC superimposition characteristics can be obtained when used as an inductor.

Further, the soft magnetic material of the present embodiment preferably contains 65 to 83 wt% of particles of the particle group α, 15 to 30 wt% of particles of the particle group β, and 1.5 to 5 wt% of the resin. With this configuration, the space between the particles of the particle group α and the particles of the particle group β can be filled with the resin, and the voids can be reduced.

Examples of the resin include various organic polymer resins such as silicone resin, phenol resin, acrylic resin and epoxy resin, but the resin is not particularly limited thereto. One of these can be used alone, or two or more of them can be used in combination. Further, if necessary, a known curing agent, cross-linking agent, lubricant or the like may be blended. Further, a liquid resin or a resin dissolved in an organic solvent may be used, but a liquid epoxy resin is preferable.

On the other hand, the soft magnetic material of the present embodiment is preferably used as a paste capable of printing and coating, and the viscosity of the paste can be adjusted with a solvent, a dispersant or the like, if necessary.

The core of the present embodiment can be produced by filling a paste containing the above-mentioned soft magnetic material in a mold having an arbitrary shape and heat-curing it. When it contains a volatile component such as a solvent, it can be produced by drying it in a semi-cured state, pressurizing it, and then heat-curing it. Since the particle size of the soft magnetic metal powder does not change in the production of the core, the particle group α and the particle group β maintain the particle size distribution in the above-mentioned soft magnetic material even in the state of the core.

The core of this embodiment can be used for various types of inductors such as thin film inductors, laminated inductors, and wound inductors. As an example, the configuration of a thin film inductor is shown. FIG. 5 is a conceptual diagram of the internal structure of the element body 5 of the thin film inductor 10, and FIG. 6 is a conceptual diagram of the appearance of the thin film inductor 10. Reference numeral 1 in FIG. 5 is a substrate using a material that can be arbitrarily selected from resin, ceramic, ferrite, and the like, and a spiral inner conductor 2 made of silver or copper is formed on the upper and lower surfaces thereof. The conductors on the upper and lower surfaces are connected by through holes formed in the substrate 1. Further, reference numeral 3 is a magnetic layer, which is the core of the present embodiment. Reference numeral 4 in FIG. 6 is an external electrode connected to the internal electrode of reference numeral 2, and the surface of the silver base electrode is nickel-plated and tin-plated on the surface.

Next, a method for manufacturing a thin film inductor will be described as an example of the inductor.

A spiral internal electrode is formed on the upper and lower surfaces of the resin substrate by a sputtering method or a photolithography method. Further, the paste-like soft magnetic material of the present embodiment is printed on the substrate surface to form a magnetic layer, which is then heat-cured at a temperature of 150 to 200 ° C. to form a mother substrate on which a plurality of spiral-shaped internal electrodes are formed. obtain. A plurality of internal electrode patterns are formed on this mother substrate, and the chips are divided into individual chips through a cutting process using a slicer, and barrel polishing or the like is performed so that the internal electrodes and the external electrodes can be easily connected. The chip thus obtained is fixed with the surface where the internal electrode is exposed facing up, and the external electrode is formed by a thin film process such as sputtering. Further, the thin film inductor can be manufactured through the steps of nickel plating and tin plating on the surface of the external electrode.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

As a soft magnetic metal powder, it is made of a spherical Fe-2.5 mass% B-6.4 mass% Si-2.1 mass% Cr-based amorphous alloy produced by a water atomization method, and its surface is insulated and coated with phosphate glass. The average particle size D50 is 72.9 μm (D10: 27.8 μm, D90: 173 μm), 56.4 μm (D10: 21.3 μm, D90: 134 μm), 51.8 μm (D10: 19.7 μm, D90: 124 μm, respectively). ), 49.0 μm (D10: 26.5 μm, D90: 87.2 μm), 47.5 μm (D10: 17.9 μm, D90: 113 μm), 21.8 μm (D10: 8.2 μm, D90: 52.1 μm) , 19.6 μm (D10: 9.4 μm, D90: 30.8 μm), 9.1 μm (D10: 3.8 μm, D90: 21.6 μm), average grain size of carbonyl iron powder prepared by the carbonyl method. Powder with a diameter D50 of 3.2 μm (D10: 1.9 μm, D90: 5.1 μm) and 1.3 μm (D10: 0.7 μm, D90: 2.0 μm), respectively, and iron powder produced by the spray thermal decomposition method. A powder having an average particle size D50 of 0.52 μm (D10: 0.30 μm, D90: 0.84 μm) was prepared.
The above "Fe-2.5 mass% B-6.4 mass% Si-2.1 mass% Cr" means that B is 2.5 mass%, Si is 6.4 mass%, and Cr is 100 mass% as a whole. Is 2.1 mass%, indicating that the balance is Fe. The same applies to the following examples.
(Example 1)
The soft magnetic metal powder of Example 1 in which powders having an average particle size D50 of 9.1 μm and 0.52 μm as particle group α and particle group β, respectively, are blended at a weight ratio of 35:10 to obtain the peak particle size in Table 1. Got Next, 2.5 wt% of a liquid epoxy resin was added, an organic solvent was added, and the mixture was sufficiently kneaded while adjusting the viscosity to obtain a paste-like soft magnetic material of Example 1. Further, a paste-like soft magnetic material is filled in a mold having a toroidal-shaped groove, dried in a semi-cured state and pressed, then taken out from the mold and further thermoset in a constant temperature bath to have an outer diameter. A toroidal-shaped core of Example 1 having a thickness of 15 mm, an inner diameter of 9 mm, and a thickness of 0.7 mm was obtained.

(Examples 2 to 4)
Example 1 except that powders having an average particle size D50 of 21.8 μm and 1.3 μm as the particle group α and the particle group β are blended in weight ratios of 30:10, 40:10, and 23:10, respectively. Under the same conditions, the soft magnetic powders, soft magnetic materials, and cores of Examples 2, 3 and 4 were obtained.

(Examples 5 to 7, 9, Comparative Examples 4, 5)
As the particle group α and the particle group β, powders having an average particle size D50 of 47.5 μm and 1.3 μm, respectively, in weight ratios of 27:10, 35:10, 45:10, 20:10, 50:10, 15 :, respectively. The soft magnetic powders, soft magnetic materials, and cores of Examples 5, 6, 7, 9 and Comparative Examples 4 and 5 were obtained under the same conditions as in Example 1 except that they were blended in 10.

(Example 8)
The soft magnetism of Example 8 under the same conditions as in Example 1 except that powders having an average particle size D50 of 47.5 μm and 3.2 μm as the particle group α and the particle group β are mixed at a weight ratio of 40:10, respectively. Powders, soft magnetic materials, and cores were obtained.

(Example 10)
The soft magnetism of Example 10 under the same conditions as in Example 1 except that powders having an average particle size D50 of 51.8 μm and 1.3 μm, respectively, were blended as the particle group α and the particle group β at a weight ratio of 33:10. Powders, soft magnetic materials, and cores were obtained.

(Example 11)
The soft magnetism of Example 11 under the same conditions as in Example 1 except that powders having an average particle size D50 of 56.4 μm and 1.3 μm as the particle group α and the particle group β are mixed at a weight ratio of 33:10, respectively. Powders, soft magnetic materials, and cores were obtained.

(Example 12)
The soft magnetism of Example 12 under the same conditions as in Example 1 except that powders having an average particle size D50 of 72.9 μm and 1.3 μm as the particle group α and the particle group β were mixed at a weight ratio of 40:10, respectively. Powders, soft magnetic materials, and cores were obtained.

(Examples 13 and 15)
Powders having an average particle size D50 of 49.0 μm, 19.6 μm, 1.3 μm, and 0.52 μm as the particle group α and the particle group β, respectively, in weight ratios of 27: 33: 12: 8, 33: 327: 12 :, respectively. The soft magnetic powder, soft magnetic material, and core of Examples 13 and 15 were obtained under the same conditions as in Example 1 except that they were blended in 8.

(Example 14, Comparative Example 1)
Powders having an average particle size D50 of 49.0 μm, 19.6 μm, 3.2 μm, and 1.3 μm as the particle group α and the particle group β at 28:30:12: 8, 27:33:12: 8 in weight ratio. The soft magnetic powder, soft magnetic material, and core of Example 13 and Comparative Example 1 were obtained under the same conditions as in Example 14 except that they were blended.

(Comparative Example 2)
The soft magnetic material and core of Comparative Example 2 were obtained under the same conditions as in Example 1 except that only the powder having an average particle size D50 of 1.3 μm was used as the soft magnetic metal powder.

(Comparative Example 3)
The soft magnetic material and core of Comparative Example 3 were obtained under the same conditions as in Example 1 except that only a powder having an average particle size D50 of 47.5 μm was used as the soft magnetic metal powder.

(Example 16)
Except for the following, the soft magnetic metal powder, soft magnetic material, and core of Example 16 were obtained under the same conditions as in Example 1. That is, in Example 16, the average particle size D50 made of a spherical Fe-2.5 mass% B-6.4 mass% Si-2.1 mass% Cr-based amorphous alloy produced by the water atomization method as the particle group α is 45. .2 μm (D10: 16.9 μm, D90: 114.0 μm) powder, carbonyl iron powder prepared by the carbonyl method as the particle group β, with an average particle size D50 of 1.3 μm (D10: 0.7 μm, D90: 2). A powder of .0 μm) was prepared, and the particle group α and the particle group β were mixed at a weight ratio of 40:10.

(Example 17)
The surface is made of a spherical Fe-2.5 mass% B-6.4 mass% Si-2.1 mass% Cr-based amorphous alloy produced by the water atomization method as the particle group α, and the surface is insulated and coated with silica. The soft magnetic metal powder, soft magnetic material, and core of Example 17 were obtained under the same conditions as in Example 16 except that the powder of 23.6 μm (D10: 8.8 μm, D90: 57.0 μm) was used. ..

(Example 18)
The surface is made of a spherical Fe-6.5 mass% Si-2.5 mass% Cr-based amorphous alloy produced by the water atomization method as the particle group α, and the surface is insulated and coated with phosphate glass. The average particle size D50 is 43. The soft magnetic metal powder, soft magnetic material, and core of Example 18 were obtained under the same conditions as in Example 16 except that a powder of 6 μm (D10: 16.2 μm, D90: 79.2 μm) was used.

(Example 19)
The surface is made of a spherical Fe-44 mass% Ni-2.1 mass% Si-4.5 mass% Co-based amorphous alloy produced by the water atomization method as the particle group α, and the surface is insulated and coated with phosphate glass. The soft magnetic metal powder, soft magnetic material, and core of Example 19 were obtained under the same conditions as in Example 16 except that the powder having a D50 of 23.0 μm (D10: 8.1 μm, D90: 56.7 μm) was used. rice field.

(Example 20)
Except for the following, the soft magnetic metal powder, soft magnetic material, and core of Example 20 were obtained under the same conditions as in Example 16. That is, in Example 20, it is made of a spherical Fe-13.0 mass% Si-9.0 mass% B-3.0 mass% Nb-1.0 mass% Cu-based amorphous alloy produced by the water atomization method as the particle group α. The surface is insulated and coated with phosphate glass, and a powder having an average particle size of D50 of 21.8 μm (D10: 8.0 μm, D90: 51.9 μm) is used, and the particle group α and the particle group β are weight-ratio. At 35:10.

(Example 21)
Except for the following, the soft magnetic metal powder, soft magnetic material, and core of Example 21 were obtained under the same conditions as in Example 16. That is, in Example 21, the surface is made of a spherical Fe-2.5 mass% B-6.4 mass% Si-2.1 mass% Cr-based amorphous alloy produced by the water atomization method as the particle group α, and the surface is a phosphate. The surface is insulated with silica, consisting of a powder having an average particle size D50 of 47.5 μm (D10: 17.9 μm, D90: 113 μm) insulated and coated with glass, and carbonyl iron powder prepared by the carbonyl method as the particle group β. A powder having an average particle size D50 of 1.3 μm (D10: 0.8 μm, D90: 2.2 μm) was prepared, and the particle group α and the particle group β were blended at a weight ratio of 30:10.

(Example 22)
The average particle size D50, which is made of Fe-50mass% Ni-based alloy produced by the spray thermal decomposition method as the particle group β and whose surface is insulated and coated with silica, is 0.8 μm (D10: 0.5 μm, D90: 1.3 μm). ) Was used, and the soft magnetic metal powder, soft magnetic material, and core of Example 22 were obtained under the same conditions as in Example 21.

(Example 23)
Same as Example 16 except that a powder having an average particle size D50 of 38.2 μm (D10: 9.4 μm, D90: 92.5 μm) composed of spherical Fe produced by the water atomization method is used as the particle group α. The soft magnetic metal powder, soft magnetic material, and core of Example 23 were obtained under the conditions of.

The measurement conditions for the particle size distribution measurement method, the filling rate of the soft magnetic gold powder, the magnetic permeability of the toroidal-shaped core, and the DC superimposition characteristics are as follows.

(Measurement of particle size distribution)
Add water, powder, and dispersant, disperse with a homogenizer (manufactured by Nippon Seiki Co., Ltd.), and peak A1, A2, ... ..., Ax (x is 1 or more), B1, B2, ..., By (y is 1 or more), and point C were determined. From the peaks and points, peak particle sizes PA1, PA2, ..., PAx (x is 1 or more), PB1, PB2, ..., PBy (y is 1 or more) and peak intensities (frequency) IA1, IA2 ,. ..., IAx (x is 1 or more), IB1, IB2, ..., IBy (y is 1 or more), particle size PC at point C, and intensity (frequency) IC were calculated. Further, in the volume-based particle size distribution, the volume Vα of the particle group α and the volume Vβ of the particle group β were calculated by setting the particle group α on the large particle size side and the particle group β on the small particle size side from the PC.
When the particle size distribution of the obtained soft magnetic material and the soft magnetic metal powder contained in the core was measured in the same manner, the same particle size distribution as that of the soft magnetic metal powder before being used for the soft magnetic material and the core was obtained. ..

(Filling rate of soft magnetic metal powder)
The density was measured by the Archimedes method using a toroidal-shaped core, and was determined from the specific gravity of various materials.

(Measurement conditions for magnetic permeability)
Toroidal core size: outer diameter: 15 mm x inner diameter: 9 mm x thickness: 0.7 mm
Measuring instrument: E4991A (manufactured by Agilent) RF impedance / material analyzer Measurement frequency: 3MHz

(Measurement conditions for DC superimposition characteristics)
Toroidal core size: outer diameter: 15 mm x inner diameter: 9 mm x thickness: 0.7 mm
Number of windings: 30 times Measuring instrument: 4284A (manufactured by Agilent) Precision LCR meter Frequency of high frequency signal: 100kHz
The DC superimposition characteristic was evaluated by the rate of decrease in the inductance value when the DC bias current was changed from 0 A to 10 A.

Table 1 shows the peak particle sizes PA1, PA2, PB1, PB2, peak intensity IA, IB, minimum intensity IC, intensity ratio IC / IA, and volume ratio Vα / Vβ of the particle groups α and β calculated from the particle size distribution measurement. The results of the filling rate, the magnetic permeability, and the inductance reduction rate of the soft magnetic powder measured from the toroidal-shaped core are shown.

In Examples 1 to 23 of Table 1, the intensity ratio IC / IA is 0.12 or less and the volume ratio Vα / Vβ is 2.0 or more and 5.1 or less between the particle group α and the particle group β in each sample. The above condition was satisfied, and the magnetic permeability showed a high value exceeding 30.

According to Table 1, in Comparative Examples 1, 4 and 5, the intensity ratio IC / IA is 0.12 or less and the volume ratio Vα / Vβ is 2.0 or more and 5.1 or less between the particle group α and the particle group β. The filling rate of the soft magnetic metal powder was low, and the magnetic permeability was less than 30. In particular, in a sample having a single particle size distribution having only a particle group α as in Comparative Examples 2 and 3, the filling rate of the soft magnetic metal powder when made into a toroidal core cannot exceed 70 vol%, and at 3 MHz. The magnetic permeability was also 20 or less.

In Examples 2, 5, 6, 13, 15, 20, and 21, the intensity ratio IC / IA is 0.01 or more and 0.06 or less, the volume ratio Vα / Vβ is 3.0 or more and 4.0 or less, and the filling is performed. The ratio exceeded 81 vol%, the magnetic permeability also showed a high value exceeding 39, the special current superimposition characteristic was good, and the inductance reduction rate was 33% or less.

In Examples 11 and 12 in which the particle size PA of the peak of the particle group α exceeds 60 μm, the relative permeability shows a relatively high value as shown in Table 1, but the rate of decrease in inductance exceeds 40%. Deterioration of DC superimposition characteristics begins to be noticeable. However, when the peak particle size PA of the particle group α was 60 μm or less, relatively good DC superimposition characteristics were obtained. It is presumed that the cause of the deterioration of the DC superimposition characteristic is largely due to the non-uniformity of the structure in the sample. This is because, as the peak particle size PA of the particle group α increases, the voids formed in the sample also tend to increase, and it is presumed that the distribution state of the resin portion and the void portion is in a textured state in which segregation is likely to occur. Because.

For the representative samples of the soft magnetic materials shown in Table 1, the particle size distribution maps of the samples are shown in FIGS. 1 to 4.

FIG. 1 is a diagram showing a particle size distribution (frequency distribution) of Example 5. The particle group α has a relatively broad particle size distribution, but since the peak particle size PA (52.3 μm) of the particle group α and the peak particle size PB (1.3 μm) of the particle group β are separated, the particles The minimum intensity IC existing between the group α and the particle group β becomes small, the filling rate of the soft magnetic metal powder at this time becomes as high as 82.6 vol%, and the magnetic permeability also shows a high value of 41.4. rice field.

FIG. 2 is a diagram showing a particle size distribution (frequency distribution) of Example 15. The particle group α has a relatively broad particle size distribution having two peaks, but the peak particle size PA (52.3 μm) of the particle group α and the peak particle size PB (1.3 μm) of the particle group β are separated. Therefore, the minimum intensity IC existing between the particle group α and the particle group β becomes small, the filling rate of the soft magnetic metal powder at this time becomes as high as 81.8 vol%, and the magnetic permeability is also 40.1. Showed a high value.

FIG. 3 is a diagram showing a particle size distribution (frequency distribution) of Comparative Example 1. The particle group α has a broad particle size distribution having two peaks, and the peak particle size PA is as small as 18.5 μm. Therefore, although the peak particle size PB of the particle group β is 3.3 μm, which is a relatively small soft magnetic metal powder, the particle group α and the particle group β are close to each other, and the particle group α and the particle group β The minimum intensity IC existing between them became large and the intensity ratio IC / IA exceeded 0.12. At this time, the filling rate of the soft magnetic metal powder was 74.7 vol%, which was lower than that of the examples, and the magnetic permeability was also a low value of 23.2.

FIG. 4 is a diagram showing a particle size distribution (frequency distribution) of Comparative Example 3. Only the particle group α did not have the minimum strength IC, and the filling rate of the soft magnetic metal powder at this time was 68.8 vol%, which was lower than that of the examples, and the magnetic permeability was also a low value of 19.5.

Since the soft magnetic material of the present invention has high magnetic permeability and excellent DC superimposition characteristics, it can be widely used for electric / magnetic devices such as inductors and various transformers, and various devices, equipments, systems, etc. equipped with them. Is.

1 Substrate 2 Internal conductor 3 Magnetic layer 4 External electrode 5 Element body 10 Thin film inductor

Claims (5)

A soft magnetic material containing soft magnetic metal powder and resin.
In the volume-based particle size distribution obtained by measurement by the laser diffraction / scattering method,
The soft magnetic metal powder is composed of a particle group α and a particle group β, the peak intensity of the particle group α is IA, the volume of the particle group α is Vα, the peak intensity of the particle group β is IB, and the volume of the particle group β. When the minimum intensity existing between Vβ, the particle group α and the particle group β is taken as IC, the intensity ratio IC / IA is 0.12 or less, and the volume ratio Vα / Vβ is 2.5 or more and 5.1 or less. Next,
In the particle size distribution of the soft magnetic metal powder, the particle group α is a particle group containing the maximum peak intensity, and the peak particle size PA of the particle group α is larger than the peak particle size PB of the particle group β.
The peak particle size PB of the particle group β is 0.5 to 5 μm, and the peak particle size PB is 0.5 to 5 μm.
When the peak intensities of the particle group α are IA1, IA2, ..., IAx (x is 1 or more) in descending order, the peak intensity IA of the particle group α is IA1 and the peak particle size PA of the particle group α is PA1. ,
When the peak intensities of the particle group β are IB1, IB2, ..., IBy (y is 1 or more) in descending order, the peak intensity IB of the particle group β is IB1 and the peak particle size PB of the particle group β is PB1. A soft magnetic material characterized by The soft magnetic material according to claim 1, wherein the peak particle size PA of the particle group α is 60 μm or less. The soft magnetic material according to claim 1 or 2, wherein the soft magnetic metal powder constituting the particle group α is a metal containing Fe or Fe and is coated with an insulating material. A core made of the soft magnetic material according to any one of claims 1 to 3. An inductor comprising the core according to claim 4.

Images