JPH0729719A - Noise absorber and noise filter - Google Patents

Abstract

PURPOSE:To realize a noise absorber and a small noise filter both more enhanced in performance by a method wherein one or more granular magnetic substances specified in grain diameter are dispersed in a non-magnetic insulator. CONSTITUTION:A noise filter is formed through such a method that a structure composed of a non-magnetic insulator 2 and a film of magnetic substance 1 bonded to the single side or both the sides of the insulator 2 is rolled into a single-layered or multilayered cylinder. The magnetic substance 1 is formed of NiFe and CoZrNb, and the non-magnetic insulator 2 is formed of SiO2. One or more granular substances of grain diameter 0.1 to 10 times as large as a skin depth are so dispersed in the non-magnetic insulator 2 as to be separated from each other by a distance of 50nm or above. By this setup, a noise absorber enhanced in performance taking advantage of an eddy current lass can be obtained, and furthermore a small noise filter can be also obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise absorber and a noise filter, and more particularly to a small noise filter.

[0002]

2. Description of the Related Art The relative permeability μ _r (f) of a magnetic material is expressed by the following equation.

Μ _r (f) = μ _r '(f) -jμ _r "(f) where μ _r ' corresponds to effective relative permeability, μ _r " corresponds to loss, and j = ( -1) ^1/2 and f are frequencies.

A noise filter using a magnetic material utilizes the noise absorption effect due to the loss of the magnetic material and is required to have high impedance and resistance to noise. Therefore, it is necessary that | μ _r | and μ _r "be large as a noise absorber. In the electromagnetic environment problem, for example, 30 to 1000, which corresponds to the broadcasting frequency of television, is used.
Noise of MHz is regarded as a problem, and it is desired to realize a noise filter that exhibits an excellent noise absorption effect in this frequency band.

FIG. 12 shows frequency characteristics of a typical relative permeability (μ _r '(0) = 1500) of a ferrite magnetic material which is a conventional material (Kennosuke Ueno, "Electromagnetic Environmental Engineering Information" p.152, Issued June 30, 1992, extra, Mimatsu Data System). Relative permeability of ferrite-based magnetic material μ
_{Between r} '(0) and the upper limit frequency f _c (defined by the frequency at which μ _r "has a peak), the limiting rule of μ _r ' (0) × f _c = 5.6 GHz (1) holds, This is due to the fact that ferrite uses magnetic resonance loss as magnetic material loss (Satoshi Konkakaku: “Physics of magnetic materials (bottom)” p.325, Shokabo). The dashed line in FIG. 12 shows the limit line of the equation (1).
Equation (1) shows that the values of | μ _r | and μ _r "are uniquely determined when the frequency characteristics of the ferrite-based magnetic material are set so that μ _r " is large in a specific frequency band. means. Therefore, in order to increase the noise absorption effect, there is a problem that the size of the component is increased in addition to increasing the volume of the component. FIG. 13 shows the shape of a noise filter that uses a ferrite magnetic material as a noise absorber, and FIG. 14 shows the frequency characteristics of its impedance. Here, the size of the noise filter is d = 10 mm, t
= 4 mm, a l = 30mm, | Z | impedance, R represents the resistance, X _L is the reactance. As a practical noise filter, an impedance of several tens Ω to 100 Ω is required, and it can be seen from FIG. 14 that this condition is satisfied, but the component size is considerably larger than other electronic components. ing.

[0006]

SUMMARY OF THE INVENTION The present invention has been proposed to solve the above-mentioned drawbacks, and an object of the present invention is to provide a higher performance noise absorber and a smaller noise filter.

[0007]

In order to solve the above problems, the noise absorber of the present invention has a granular magnetic material having a particle size of 0.1 to 10 times the skin depth in a non-magnetic insulator. Body 1
It is characterized by being dispersed at intervals of not less than 50 nm and not less than 50 nm.

Further, the noise filter of the present invention is characterized in that a structure in which a non-magnetic insulator is bonded to one side or both sides of a film-shaped magnetic body is wound in a cylindrical shape more than once. . Alternatively, in the non-magnetic insulator, the skin depth of 0.
One or more granular magnetic bodies having a grain size of 1 to 10 times 5
It is characterized in that the noise absorbers dispersed at intervals of 0 nm or more are wound in a single cylinder or more.

[0009]

According to the present invention, the noise absorbing effect due to the eddy current loss of the magnetic body can be efficiently utilized, so that a high-performance noise absorbing body and a small noise filter can be realized.

The noise filter of the present invention is manufactured by forming a non-magnetic insulator on one or both sides of a film-shaped magnetic material and winding it in a tubular shape in a single layer or a plurality of layers. Alternatively, in the non-magnetic insulator, one or more granular magnetic bodies having a grain size of 0.1 to 10 times the skin depth are dispersed at a spacing of 50 nm or more, and a single or plural noise absorbers are cylindrically formed. It is made by stacking and winding.

[0011]

The present invention will be described in more detail with reference to the following examples.

(Embodiment 1) FIG. 1 is a view showing an embodiment of a noise filter of the present invention, in which a magnetic body 1 as shown in FIG. 2 has a film shape, and one side of the magnetic body 1 (see FIG. (A)) or a structure in which a non-magnetic insulator 2 is bonded to both surfaces (FIG. 2 (b)), and the structure is formed by winding one or a plurality of layers in a cylindrical shape.

The structure of FIG. 2 has an ion beam sputter (I
BS) method. The sputtering conditions were an operating vacuum degree of 1 × 10 ⁻⁴ Torr (using Ar as a sputtering gas), an acceleration voltage of 1 KV, and a substrate temperature of 160 ° C.
The target is a CoZr-based amorphous alloy for magnetic material (eg, CoZrNb [film composition: 87, 5, 8 at
%]), NiFe alloy (film composition: 82.5, 17.5a
t%), SiO ₂ was used for the non-magnetic insulator, and glass (Corning No. 0211) was used for the substrate. To obtain a large relative magnetic permeability, Ni is used as a magnetic material.
When Fe was used, film formation was performed in a magnetic field by applying a magnetic field of about 100 Oe. When CoZr-based amorphous alloy was used, after film formation in a magnetic field, heat treatment was performed in a rotating magnetic field.

In order to produce a cylindrical noise filter, the structure produced on the substrate as described above was peeled from the substrate, and a sheet-shaped product was rolled into a cylindrical shape.

In addition to the above-mentioned IBS method, an RF sputtering method, a magnetron sputtering method, a vapor deposition method, a plating method, a roll method, a coating method, a screen printing method, a rolling method, or the like may be used as another manufacturing method. The effect of can be obtained.

As a method of forming a cylindrical shape, in addition to using the sheet peeled from the substrate as described above, a film-shaped magnetic material is directly formed on a flexible non-magnetic insulator sheet such as polyimide. There is a method of forming it and rolling it into a cylindrical shape.

FIG. 3 is a schematic view of FIG. 2 (a) and (b).
It is a diagram illustrating a relationship between the relative magnetic permeability and the thickness t _m of the magnetic body 1. NiFe and CoZrNb are used as the magnetic body 1, and SiO ₂ (0.1 μm thick) is used as the non-magnetic insulator 2.
It was used.

In FIG. 3, the relative magnetic permeabilities μ _r 'and μ _r "are standardized by the static relative magnetic permeability μ _r ' (0), and t _m is standardized by the skin depth δ. The skin depth δ is δ = [2ρ _m / (2πfμ _r '(0) μ using the electric resistivity ρ _m of the magnetic substance, μ _r ' (0), the frequency f, and the magnetic permeability μ _{0 of the} vacuum. ₀ )] ^1/2 (2) In the case of NiFe, μ _r '(0) = 2500, ρ
_m = 20 μΩcm, and for CoZrNb μ _r '(0) =
5000, ρ _m = 120 μΩcm. As shown in FIG. 3, μ _r "has a large value due to the eddy current loss when t _m / δ is in the range of 0.1 to 10. Therefore, large μ _r "
It can be seen that it is effective to set t _m to be 1/10 to 10 times the thickness of δ in order to realize

In FIGS. 2A and 2B, the magnetic body 1
As μ _r '(0) = 5000, ρ _m = 120 μΩcm, t _m
4 shows the frequency characteristic of relative permeability when CoZrNb of 2 μm is used and SiO ₂ (0.1 μm thickness) is used as the non-magnetic insulator 2. δ is 0.4 to 1.4 μm at 30 to 1000 MHz, and t _m is δ / 10 ≦ t _m ≦ 10.
δ is satisfied. μ _r '(0) = 5000, f _c = 15M
From Hz, the product μ _r '(0) × f _c becomes 75 GHz,
It is 10 times or more compared with the equation (1). As a result, 30-1
At 000 MHz, | μ _r |, μ _r "has a value larger than the value in the ferrite-based magnetic body of FIG.

Next, in FIGS. 2A and 2B, as the magnetic body 1, μ _r '(0) = 5000, ρ _m = 120 μΩc
FIG. 5 shows the impedance frequency characteristics of the noise filter formed as shown in FIG. 1 using CoZrNb of m, t _m = 2 μm and SiO ₂ (0.1 μm thickness) as the non-magnetic insulator 2. The size of the noise filter is d = 3 mm, t
= 60 μm and l = 10 mm. In this embodiment, 30
~ 1000MHz impedance is several tens to 300Ω
This is equivalent to the conventional part shown in FIG. 14, and the part volume could be reduced to about 1/10 ² .

(Embodiment 2) FIG. 6 shows an embodiment of the magnetic particle dispersion type noise absorber of the present invention, in which one or a plurality of magnetic bodies 1 are granular and the granular magnetic bodies 1 are non-magnetic insulators. It is dispersed in 2. The size of the magnetic body 1 is 1/10 to 10 times the skin depth, and the magnetic bodies are placed by the non-magnetic insulator 2 at a distance of 50 nm or more.

The magnetic particle-dispersed noise absorber was prepared by the ion beam sputtering (IBS) method. The sputtering conditions are: operating vacuum degree: 1 × 10 ⁻⁴ Torr (using Ar as a sputtering gas), accelerating voltage: 1 kV, substrate temperature: 160
℃ was made. The target is a CoZr-based amorphous alloy (for example, CoZrNb [film composition: 87, 5, 8 at
%]) And a composite target of SiO ₂ or Ni
Fe alloy (film composition: 82.5, 17.5 at%) and Si
A composite target with O ₂ is used, and glass (Co
running No. 0211) was used. In order to obtain a large relative magnetic permeability, when NiFe is used as a magnetic material, film formation is performed in a magnetic field by applying a magnetic field of about 100 Oe, while when a CoZr-based amorphous alloy is used as a magnetic material, a magnetic field is increased. After the intermediate film formation, heat treatment was performed in a rotating magnetic field. In order to produce a cylindrical noise filter, a method was used in which the noise absorber produced on the substrate as described above was peeled from the substrate and formed into a sheet shape, which was rolled into a cylindrical shape.

As other manufacturing methods, besides the above IBS method, RF sputtering method, magnetron sputtering method, vapor deposition method, roll method, coating method, screen printing method, and magnetic particles are mixed in a non-magnetic insulating paste. The same effect can be obtained by using the method. Further, as a method of forming a cylindrical shape, in addition to using the sheet peeled from the substrate as described above, a method of using a sheet deposited on a cylindrical substrate, a method of hollowing out a bulk shape into a cylindrical shape, a paste shape There is a method of molding the product into a cylindrical shape from the beginning.

FIG. 7 is a diagram showing the relationship between the relative magnetic permeability of the magnetic body 1 of FIG. 6 and the particle size d _m . NiF as the magnetic body 1
e and CoZrNb, SiO ₂ was used as the non-magnetic insulator 2, and the distance between the magnetic substances was 0.1 μm.

In FIG. 7, the relative magnetic permeabilities μ _r 'and μ _r "are standardized by the static relative magnetic permeability μ _r ' (0), and d _m is standardized by the skin depth δ. In NiFe, μ _r '(0) =
2500, ρ _m = 20 μΩcm, for CoZrNb μ _r '
(0) = 5000 and ρ _m = 120 μΩcm. As shown in the figure, μ _r "has a large value due to the eddy current loss when d _m / δ is in the range of 0.1 to 10. Therefore, to realize a large μ _r " d _m It can be seen that it is effective to set the thickness to 1/10 to 10 times.

Next, as the magnetic material 1, μ _r '(0) = 250
0, ρ _m = 20 μΩcm, NiFe, non-magnetic insulator 2
As a result, the frequency characteristic of relative permeability was measured by using SiO ₂ as the material and varying the distance d _n between the magnetic materials. The results are shown in Fig. 8.
Here, the grain size d _m of NiFe was set to 50 nm. The skin depth of NiFe in this frequency band is 0.16 to
It is 1.6 μm, and the NiFe particle size of 50 nm is sufficiently smaller than this. Therefore, if SiO ₂ maintains the electrical insulation between NiFe, the magnetic resonance frequency of NiFe is 650M.
Up to Hz, μ _r 'is constant and μ _r "has a low value.
If d _n is as small as 5 nm, μ _r 'from around 30 MHz
, And a sharp increase in μ _r ", resulting in incomplete electrical insulation. On the other hand, 650 at d _n = 50 nm.
Μ _r 'is constant up to MHz, electrical insulation is almost maintained, and when d _n = 100 nm, the insulation effect becomes more reliable. As described above, in order to maintain the electrical insulation between the magnetic bodies, it is effective to set the distance between the magnetic bodies to 50 nm or more.

In FIG. 6, as the magnetic body 1, μ _r '(0) =
CoZ of 5000, ρ _m = 120 μΩcm, d _m = 2 μm
FIG. 9 shows the frequency characteristic of relative permeability when rNb is SiO ₂ as a non-magnetic insulator. Where d _n
= 0.1 μm. δ is 30 to 1000 MHz and 0.
4 to 1.4 μm, and d _m satisfies δ / 10 ≦ d _m ≦ 10δ. Also, μ _r '(0) = 5000, f _c = 15
From MHz, the product _{μ r '(0) × f} c is a 75 GHz (1)
It is 10 times more than the formula. As a result, 30 to 1000
In MHz, | μ _r |, μ _r "has a larger value than that in the ferrite-based magnetic body of FIG.

FIG. 10 shows an embodiment of a noise filter using the noise absorber of FIG. FIG. 10 shows the noise absorber of FIG. 6 which is formed by winding a single or plural layers in a cylindrical shape.

FIG. 11 shows frequency characteristics of impedance in the noise filter of FIG. Here, the magnetic body 1
As μ _r '(0) = 5000, ρ _m = 120 μΩcm, d _m
= 2 μm of CoZrNb as a non-magnetic insulator
₂ was used and d _n = 0.1 μm. δ is 30 to 1000
0.4-1.4 μm at MHz, d _m δ / 10 ≦
d _m ≦ 10δ is satisfied. The size of the noise filter is d = 3 mm, t = 60 μm, 1 = 10 mm. Three
The impedance of 0-1000MHz is several tens to 300
Ω is equivalent to that of the conventional component shown in FIG. 14, and at this time, the component volume could be reduced to about 1/10 ² .

The magnetic substance 1 is made of Fe, Ni, C.
On the other hand, an alloy-based magnetic material based on o is used as the non-magnetic insulator 2, and SiO ₂ , AlN, Al ₂ O ₃ , BN and Ti are used as the non-magnetic insulator 2.
Even if N, SiC, polyimide, rubber or the like is used, the same effect as described above can be obtained.

As described above, according to the present invention, it becomes possible to reduce the size of parts as compared with the conventional noise filter.

[0032]

As described above, according to the present invention,
A high-performance noise absorber utilizing eddy current loss can be obtained,
Furthermore, it becomes possible to provide a small noise filter.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment of a noise filter of the present invention.

FIG. 2 is a schematic diagram showing details of a noise filter of the present invention.

FIG. 3 is a graph showing the dependence of relative permeability on the thickness of a magnetic layer.

FIG. 4 is a graph showing frequency characteristics of relative permeability.

FIG. 5 is a graph showing frequency characteristics of impedance.

FIG. 6 is a conceptual diagram showing an embodiment of the noise absorber of the present invention.

FIG. 7 is a graph showing the dependency of relative magnetic permeability on the particle size of magnetic material.

FIG. 8 is a graph showing frequency characteristics of relative permeability when the distance between magnetic bodies is changed.

FIG. 9 is a graph showing frequency characteristics of relative permeability.

FIG. 10 is a schematic view showing another embodiment of the noise filter of the present invention.

FIG. 11 is a graph showing frequency characteristics of impedance.

FIG. 12 is a graph showing frequency characteristics of relative permeability in a conventional material (ferrite magnetic material).

FIG. 13 is a schematic diagram showing an example of a conventional noise filter.

FIG. 14 is a graph showing impedance frequency characteristics of a conventional material (ferrite magnetic material).

[Explanation of symbols]

 1 magnetic substance, 2 non-magnetic insulator.

Claims (3)

[Claims] 1. A skin depth of 0.1 to 0.1 in a non-magnetic insulator.
One or more granular magnetic materials having a particle size 10 times, 50n
A noise absorber characterized by being dispersed at an interval of m or more. 2. A noise filter comprising a structure in which a non-magnetic insulator is bonded to one surface or both surfaces of a film-shaped magnetic material, and the structure is wound in a cylindrical shape in a single layer or more. 3. A skin depth of 0.1 to 0.1 in a non-magnetic insulator.
One or more granular magnetic materials having a particle size 10 times, 50n
A noise filter characterized in that a noise absorber, which is dispersed at intervals of m or more, is wound in a cylindrical shape in a single layer or more.