JP2884513B1 - Noise absorbing element using composite magnetic material - Google Patents

Abstract

Abstract: PROBLEM TO BE SOLVED: To improve a frequency characteristic of impedance by using a composite magnetic material containing Si-Fe-based metal magnetic powder as a main component, and to improve GH from a MHz band conducting on a line.
Electromagnetic interference noise in the z band can be suppressed. SOLUTION: A conducting wire 2 is provided so as to penetrate a composite magnetic body 1 mainly composed of a Si-Fe-based metal magnetic powder.
The composite magnetic body 1 is a molded composite magnetic material obtained by mixing and kneading a Si—Fe-based metal magnetic powder and a thermoplastic resin powder as a binder, and heating and molding the mixture into a cylindrical shape. If necessary, a means for integrating the composite magnetic body 1 and the conductor 2 is added.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an element for suppressing electromagnetic interference noise (noise) in a line,
It is possible to suppress unnecessary electromagnetic interference noise from the MHz band to the GHz band, which is generated in the printed circuit board of electronic equipment such as digital equipment and conducted on the lines of power supply system, signal system, control system, etc. The present invention relates to a noise absorbing element using a composite magnetic material capable of preventing electromagnetic interference noise from the MHz band to the GHz band from entering from outside through each line into a circuit in a printed circuit board.

[0002]

2. Description of the Related Art Conventionally, unnecessary electromagnetic interference noise generated in a printed circuit board of an electronic device and conducted on lines of a power supply system, a signal system, a control system, and the like is suppressed, and a printed circuit board is externally provided through the above-described lines. Lead-through type (lead wire insertion / penetration structure) or surface mount type (conductor insertion / penetration structure) or silver paste applied as a through conductor on the noise absorbing element to prevent intrusion into internal circuits Ferrite bead filters). The lead-through type is disclosed in Japanese Utility Model Publication No. 57-58747, and the surface mount type is described in a product catalog of the present applicant.

FIGS. 17 and 18 show examples of use of this type of noise absorbing element. FIG. 17 shows a clock signal generating circuit 20.
FIG. 18 shows an example in which the noise absorbing element 30 is inserted between the inverter logic elements 21 and 22. FIG.

[0004]

In recent years, as the operation of a circuit in a printed circuit board of an electronic device has become higher in frequency, the frequency component of the electromagnetic interference noise derived has been extended to the GHz band. In the case of a conventional ferrite bead filter using ferrite, samples A, B, and C shown in FIG.
As can be seen from the example of frequency characteristics of the complex relative magnetic permeability (μr′−jμr ″) of ferrite, frequency dispersion of magnetic permeability occurs in the MHz band, and the real part (μr) of the ferrite complex relative magnetic permeability reaches the GHz band. ′) And the imaginary part (μr ″) disappear, and as can be seen from the frequency characteristic of the impedance of the ferrite bead filter in FIG. As a result, there is a problem that the function of suppressing electromagnetic interference noise in the GHz band is considerably deteriorated.

[0005] In view of the above, the present invention improves the frequency characteristics of impedance by using a composite magnetic material containing Si-Fe-based metal magnetic powder as a main component, and improves the frequency characteristics from the MHz band that is conducted on the line. An object of the present invention is to provide a noise absorbing element using a composite magnetic material capable of suppressing electromagnetic interference noise in the GHz band.

[0006] Other objects and novel features of the present invention will be clarified in embodiments described later.

[0007]

In order to achieve the above object, a noise absorbing element using the composite magnetic material of the present invention comprises:
A conductor is provided so as to penetrate a magnetic body at least partially composed of a composite magnetic material mainly composed of a Si-Fe-based metal magnetic body powder.

[0008] In the noise absorbing element using the composite magnetic material, a part of the magnetic material may be made of ferrite.

[0009] The molded body of the composite magnetic material may be provided so as to cover at least a part of the ferrite.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a noise absorbing element using a composite magnetic material according to the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show a first embodiment of the present invention, which constitutes a lead-through type bead filter. In these figures, 1 is a composite magnetic material,
Reference numeral 2 denotes a round conductive wire having a circular cross section as a through conductor, and the composite magnetic body 1 serving as a main element of the bead filter is made of Si-Fe
-Based metallic magnetic powder (scale shape, width 10 μm, length 40 ~
This is a molded body of a composite magnetic material obtained by mixing and kneading a thermoplastic resin (for example, a polyester-based resin) powder as a binder and heating and molding into a cylindrical shape. Here, as the composite magnetic body 1, a molded body of the composite magnetic material may be integrally molded directly around the round conductor 2 by a plastic molding method and fixed to the round conductor 2,
After a molded body of a composite magnetic material is prepared in advance so as to have a through hole for conducting wire insertion, the conducting wire 2 may be inserted into the through hole of the molded body.

The upper limit of the weight ratio of the Si-Fe-based flaky metal magnetic powder in the composite magnetic material 1 is limited to 80% of the magnetic powder and 20% of the binder powder due to restrictions on the molding surface of the plastic molding method. The rank is the target. In addition,
The lower limit of the mixing ratio of the magnetic powder must be 50% by weight or more in order to secure a sufficient attenuation. If the amount is less than 50% by weight, the properties as a magnetic material are greatly reduced.

FIG. 3 shows the complex relative magnetic permeability (μr ′) of the composite magnetic material obtained by heating and molding by the plastic molding method using 80% of the Si-Fe-based flaky metal magnetic material powder and 20% of the binder powder. −jμr ″). FIG.
9, the frequency dispersion of the magnetic permeability can be shifted to the higher frequency side,
The use of Si-Fe-based flake-shaped metal magnetic material powder can increase the values of μr ′ and μr ″, and
It is suitable for use in the z band. The complex relative magnetic permeability (μr′−jμr ″) shown in FIG. 3 is required to show as large a value as possible up to a high frequency region in terms of attenuation in the GHz band, and the real number of the complex relative magnetic permeability at 1 GHz is required. The part μr ′ is preferably 3 or more, and the imaginary part μr ″ is preferably 2 or more.

FIG. 4 shows that a cylindrical composite magnetic material having an outer diameter of 3.5 mm and a length of 6.0 mm is connected to a lead wire having a wire diameter of 0.65φ by the Si.
-Fe-based flaky metal magnetic powder 80%, binder 20%
It is a frequency characteristic of impedance when heated and molded at a compounding ratio of, and it can be seen that a bead filter that suppresses conducted electromagnetic interference noise in the GHz band can be realized.

Although the first embodiment does not specifically refer to a structure for integrating the molded composite magnetic body 1 and the round conductor 2 with each other, for example, FIGS. 7 can be adopted.

FIG. 5 shows a second embodiment of the present invention.
The composite magnetic body 1 is fixed to the round conductor 2 by inserting the round conductor 2 into the composite magnetic body 1 previously formed into a cylindrical shape with a through hole and forming the flat portion 3 in the round conductor 2. doing. The material of the composite magnetic body 1 is the same as that of the first embodiment.

FIG. 6 shows a third embodiment of the present invention.
The composite magnetic body 1 is formed into a round conductor 2 by inserting a round conductor 2 into a composite magnetic body 1 previously formed into a cylindrical shape with a through hole and applying an adhesive 4 to both end surfaces of the composite magnetic body 1. It is fixed for. The material of the composite magnetic body 1 is the same as that of the first embodiment.

FIG. 7 shows a fourth embodiment of the present invention.
The round conducting wire 2 is inserted into the composite magnetic body 1 previously formed into a cylindrical shape with a through hole, and the eyelets 5 are inserted from both sides of the round conducting wire 2 to fit into both ends of the through hole of the composite magnetic body 1. Thus, the composite magnetic body 1 is fixed to the round conductor 2.
The material of the composite magnetic body 1 is the same as that of the first embodiment.

FIGS. 8 to 10 show a fifth embodiment of the present invention, which constitutes a surface mount type bead filter. In these figures, reference numeral 11 denotes a composite magnetic body, 12 denotes a rectangular conducting wire having a rectangular cross section, and the composite magnetic body 11 serving as a main element of the bead filter is provided around the rectangular conducting wire 12 in a chip shape (a rectangular parallelepiped shape). I have. This composite magnetic body 1
The material of 1 is the same as that of the first embodiment. In addition, the composite magnetic body 11 may be formed and fixed by integrally molding a molded body of a composite magnetic material directly around the rectangular conductor 12 by a plastic molding method, or may have a slit-shaped through hole for inserting the rectangular conductor in advance. After preparing the chip-shaped molded body of the composite magnetic material so as to have, the rectangular conductor 12 may be inserted into the slit-shaped through hole of the molded body. The portions of the rectangular conductor 12 extending to both sides of the composite magnetic body 11 are formed on the surface-mounting terminals by L-shaped bending.

The fifth embodiment has an advantage that it can be surface-mounted on a printed circuit board surface.

FIG. 11 shows a sixth embodiment of the present invention, which constitutes a surface mount type bead filter. In this figure, 11 is a composite magnetic body, 15 is a through conductor penetrating through the center of the composite magnetic body, and the composite magnetic body 11 which is a main element of the bead filter has a chip shape ( (A rectangular parallelepiped shape). The material of the composite magnetic body 11 is the same as that of the first embodiment. Further, the composite magnetic body 11 may be formed and fixed by integrally molding a molded body of a composite magnetic material directly around the through conductor 15 by a plastic molding method, or a slit-shaped through hole for inserting a through conductor may be formed in advance. After producing the chip-shaped molded body of the composite magnetic material so as to have the same, the through conductor 15 may be inserted into the slit-shaped through hole of the molded body. External electrodes 16 as surface mounting terminals connected to the through conductors 15 are formed on both ends of the composite magnetic body 11 by plating or the like.

In the case of the sixth embodiment, it is convenient to reduce the outer diameter.

FIGS. 12 and 13 show a seventh embodiment of the present invention, in which a ferrite bead is added to form a magnetic material through which a conductor penetrates into a lead-through type in which a composite magnetic material and ferrite are combined. It shows a bead filter. In these figures, 1 is a cylindrical composite magnetic body, 2 is a round conductor having a circular cross section, 6 is a cylindrical ferrite bead, and the round conductor 2 is a composite magnetic body 1 and a ferrite bead 6 adjacent thereto. Penetrates both. The material of the composite magnetic body 1 is the same as that of the above-described first embodiment, and the fixing of the composite magnetic body 1 and the ferrite beads 6 to the round conducting wire 2 has, for example, the configuration shown in FIGS. be able to.

In the seventh embodiment, the composite magnetic body 1
And the impedance obtained from the complex relative permeability of the ferrite bead 6 are added to increase the impedance in a wide frequency range from the MHz band to the GHz band, and from the MHz band to the GHz band. Over a wide frequency range. FIG. 14 illustrates the effect of the combined structure of the composite magnetic body 1 and the ferrite beads 6. In the case where the sample has an inner diameter of 0.65 mm, an outer diameter of 3.5 mm, and a length of 6 mm, a sample having a ferrite as a whole can be used. It can be seen that the combined structure of the half of the composite magnetic material and the ferrite exhibits higher impedance from the MHz band to about 2 GHz as compared with the sample in which the whole is a composite magnetic material.

FIG. 15 shows an eighth embodiment of the present invention, which constitutes a lead-through type bead filter to which ferrite beads are added. In these figures, 1 is a composite magnetic material, 2 is a round conducting wire having a circular cross section, and 6 is a ferrite bead. The composite magnetic material 1 is made of a composite magnetic material so as to cover the outer peripheral surface and both end surfaces of the ferrite bead 6. The molded body is integrally molded around the round conductor 2. The material of the composite magnetic body 1 is the same as that of the first embodiment, and the ferrite beads 6 are fixed to the round conductor 2 by directly molding the composite magnetic body 1 around the round conductor 2. The structure can also serve as a double.

The composite magnetic body 1 may cover the entire ferrite bead 6 or may cover only a part thereof.

In the eighth embodiment, too,
The electromagnetic interference noise suppressing effect can be exhibited in a wide frequency range from the band to the GHz band.

FIG. 16 shows a ninth embodiment of the present invention, which constitutes a surface mount type bead filter to which ferrite beads are added. In this figure, 11 is a composite magnetic material, 12 is a rectangular conductor having a rectangular cross section, 13 is a rectangular ferrite bead, and the composite magnetic material 11 is a rectangular conductor 12.
The molded body of the composite magnetic material is integrally molded in a substantially rectangular cylindrical shape around the rectangular conducting wire 12 so as to cover the outer periphery and both end surfaces of the ferrite beads 13 penetrated by. The material of the composite magnetic body 11 is the same as that of the first embodiment,
By directly molding the composite magnetic body 11 around the rectangular conductor 12, a structure that also serves to fix the ferrite beads 13 to the rectangular conductor 12 can be obtained.

The composite magnetic body 11 may cover the entire ferrite bead 13 or may cover only a part thereof.

In the ninth embodiment, in addition to the effects of the eighth embodiment, there is an advantage that it can be surface-mounted on a printed circuit board.

It is also possible to adopt a structure in which a rectangular cylindrical composite magnetic material and a rectangular cylindrical ferrite bead which are separately molded in advance into the rectangular conductor 12 are inserted as shown in FIGS. The ferrite beads used in the present invention are preferably Ni-Zn-based or the like suitable for use in a high frequency band.

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.

[0033]

As described above, according to the noise absorbing element using the composite magnetic material according to the present invention, the following effects can be obtained.

(1) A bead filter having a high impedance value in the GHz band can be formed. In other words, in the GHz band,
The composite magnetic material having a large imaginary part (μr ″) of the complex relative magnetic permeability (a molded product of a composite magnetic material mainly composed of a Si—Fe-based metal magnetic material powder), which is related to the absorption of electromagnetic interference noise, provides resistance. A bead filter rich in components (= ωμr ″ Lo) can be formed.

(2) Further, by combining with a ferrite bead filter having a high impedance value in the MHz band, a bead filter having a high impedance value in a wide band that covers the MHz band to the GHz band can be realized.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment of a noise absorbing element using a composite magnetic material according to the present invention.

FIG. 2 is a front sectional view of the same.

FIG. 3 is a graph showing a frequency characteristic of a complex relative magnetic permeability of the composite magnetic material used in the first embodiment.

FIG. 4 is a graph illustrating frequency characteristics of impedance of the noise absorbing element according to the first embodiment.

FIG. 5 is a front view showing a second embodiment of the present invention.

FIG. 6 is a front view showing a third embodiment of the present invention.

FIG. 7 is a front sectional view showing a fourth embodiment of the present invention.

FIG. 8 is a front view showing a fifth embodiment of the present invention.

FIG. 9 is a plan view of the same.

FIG. 10 is a side view of the same.

FIG. 11 is a perspective view showing a sixth embodiment of the present invention.

FIG. 12 is a perspective view showing a seventh embodiment of the present invention.

FIG. 13 is a front sectional view of the same.

FIG. 14 is a graph showing frequency characteristics of impedance of a noise absorbing element in which a ferrite and a composite magnetic body are combined.

FIG. 15 is a front sectional view showing an eighth embodiment of the present invention.

FIG. 16 is a front sectional view showing a ninth embodiment of the present invention.

FIG. 17 is a circuit diagram showing an example of using a high-frequency noise absorbing element.

FIG. 18 is a circuit diagram showing another usage example of the high-frequency noise absorbing element.

FIG. 19 is a graph showing a frequency characteristic of a complex relative magnetic permeability of ferrite.

FIG. 20 is a graph showing frequency characteristics of impedance of a conventional noise absorbing element using ferrite beads.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 11 Composite magnetic body 2 Round conductor 3 Flat part 4 Adhesive 5 Eyelet 6, 13 Ferrite bead 12 Rectangular conductor 15 Through conductor 16 External electrode

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshiki Sasaki 1-1-13 Nihonbashi, Chuo-ku, Tokyo TDK Corporation (72) Inventor Yoshiaki Akachi 1-13-1 Nihonbashi, Chuo-ku, Tokyo (56) References JP-A-9-82528 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01F 1/20 H01F 17/04

Claims (3)

(57) [Claims] 1. A composite magnetic material comprising a magnetic material at least partially composed of a composite magnetic material containing Si—Fe-based metal magnetic material powder as a main component and having a conductor penetrated therethrough. Noise absorbing element. 2. The noise absorbing element using a composite magnetic material according to claim 1, wherein a part of said magnetic body is made of ferrite. 3. The noise absorbing device using a composite magnetic material according to claim 2, wherein a molded body of the composite magnetic material is provided so as to cover at least a part of the ferrite.