JPH11186045A - Noise removal part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a noise removal part for a based structure which is able to remove high frequency noise more accurately. SOLUTION: This noise removal part includes a beaded structure, having magnetic members 1 and 2 and conductors 3, 4 and 5 penetrating through the magnetic members, and also includes a grounding electrode 6 provided on substantially full outer surfaces of the magnetic members except for end faces for the lead-out to the outside of the conductors and not contacted with the conductors. Thereby a noise filter can be provided which is of a distribution constant type and of a simple structure, which is capable of reliably removing high frequency noise.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise removing component, and more particularly to a technique for forming a distributed constant type noise filter having excellent high frequency characteristics using a bead structure.

[0002]

2. Description of the Related Art In recent years, with the demand for digitalization of various electronic devices and stricter regulations on noise, demand for noise removing components has been rapidly increasing. Also, the frequency of electronic devices has been rapidly increasing, such as the frequency of a clock in a CPU of a personal computer, and the necessity of removing noise up to a high frequency band has been increasing.

There are many types of noise removing components such as capacitors. Among them, beads are ground (G
ND) High frequency noise components can be removed simply by inserting them in series into signal lines or power supply lines without considering patterns, and because the structure is simple, inexpensive and compact,
Widely used as noise removal components.

FIG. 9 is a perspective view showing a schematic appearance of a conventional bead, and FIG. 10 is a perspective view schematically showing each component of the bead of FIG. FIG. 11 is a schematic equivalent circuit diagram of the beads of FIG. The conventional beads 30 shown in these figures have two cores 1 made of a magnetic material such as ferrite.
And 2 and three lead frames 3 to 5 made of metal or the like sandwiched between the cores 1 and 2.

[0005] In the beads 30 having such a configuration, the lead frames 3 to 5 are mounted in accordance with grooves provided in at least one of the cores 1 and 2, for example, the core 2.
The lead frames 3 to 5 are sandwiched by the steps (2) and (2), and are bonded to each other with an adhesive. The beads 30 are of an array type in which three beads are one product, but the number of beads to be combined, that is, the number of lead frames sandwiched between cores can be any number other than three. . In addition to a structure in which a lead frame is sandwiched between two cores, for example, a structure in which a lead frame is inserted into one core having a hole may be adopted.

Conventional beads having such a structure are as follows:
Utilizing the high-frequency high-frequency impedance characteristics of the magnetic material such as ferrite that constitutes the core, unnecessary high-frequency noise in signals that pass through the lead frame can be absorbed by the magnetic material, thus effectively removing noise. be able to.

[0007]

However, the conventional beads are inductance elements, and function as so-called lumped element elements. For this reason, due to the frequency characteristics of the magnetic permeability (μ) of the magnetic material constituting the core, the noise removing effect can be exhibited only up to the resonance frequency. In general, the resonance frequency of the ferrite used for the core of the bead is about 1 GHz at the maximum, so that the conventional bead has a frequency of 1 GHz.
It is difficult to accurately remove noise having a frequency exceeding z, and it has not been possible to completely cope with higher frequencies of electronic devices.

SUMMARY OF THE INVENTION An object of the present invention is to provide a noise elimination component that can more accurately remove high-frequency noise in view of such conventional problems.

Another object of the present invention is to further enhance the noise removing effect of the beads in a high frequency band.

[0010]

In order to achieve the above object, according to the first aspect of the present invention, a noise removing component is a bead comprising a magnetic material and at least one conductor penetrating the inside of the magnetic material. And a ground electrode provided on the outer surface of the magnetic material of the bead structure so as to surround the conductor and not to contact the conductor. As a result, it is possible to provide a noise removing component having excellent attenuation characteristics in a high frequency band.

Further, according to the invention described in claim 2, according to claim 1
In the noise elimination component according to (1), the number of conductors passing through the inside of the magnetic body is plural. Thus, the noise removing component can have an array structure.

According to the third aspect of the present invention, in the first aspect,
Or in the noise removing component according to any one of
The ground electrode is configured to be provided in at least a half or more area of the outer surface of the magnetic body other than the end face from which the conductor is taken out. This makes it possible to improve the attenuation characteristics in a high frequency and a wide band.

[0013] According to the fourth aspect of the present invention, in the first aspect,
Or in the noise removing component according to any one of
The ground electrode is configured to be provided on substantially the entire outer surface of the magnetic body other than the end face from which the conductor is taken out. As a result, the attenuation characteristics in a high frequency and a wide band can be made extremely excellent.

According to a fifth aspect of the present invention, the noise elimination component includes a laminate of at least one linear internal electrode layer and magnetic layers provided above and below the internal electrode layer.
Terminal electrodes are provided on the outer surface of the laminate, on both sides of which the internal electrode layers are respectively extracted to the outside, and are respectively connected to both ends of the internal electrode layer, and on the outer surface of the laminate, A ground electrode provided so as to surround the internal electrode layer and not to contact the terminal electrode. This makes it possible to provide a small laminated component noise elimination component having excellent attenuation characteristics in a high frequency band. It is easy to downsize the product and mount it on a board.

According to the invention described in claim 6, in claim 5,
In the noise elimination component according to (1), the number of the internal electrode layers is plural. Thus, the noise removing component can have a small array structure.

According to the seventh aspect of the present invention, in the fifth aspect,
Or in the noise removing component according to any one of the above items 6,
The ground electrode is configured to be provided in at least a half or more region of the outer surface of the laminate other than the surface on which the terminal electrode is provided. This makes it possible to improve the attenuation characteristics in a high frequency and a wide band.

According to the invention described in claim 8, in claim 5.
Or in the noise removing component according to any one of the above items 6,
The ground electrode is configured to be provided on substantially the entire outer surface of the laminate other than the surface on which the terminal electrodes are provided. As a result, the attenuation characteristics in a high frequency and a wide band can be made extremely excellent.

According to the ninth aspect of the present invention, in the fifth aspect,
9. The noise removing component according to any one of items 8 to 8, further comprising a reinforcing cover that covers a periphery of the laminate having a ground electrode provided on an outer surface. Thereby, mechanical strength can be increased. For this reason,
It is possible to accurately prevent damage to the noise removing component when mounting on a printed wiring board or when the board is bent.

According to the tenth aspect of the present invention, in the noise removing component according to the ninth aspect, the reinforcing cover is configured to have conductivity. This makes it possible to connect the ground electrode to the ground via the reinforcing cover.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a noise removing component according to the present invention will be described with reference to the drawings. FIG. 1 shows the first embodiment of the present invention.
It is a perspective view which shows the schematic structure of the noise removal component which concerns on 2nd Embodiment. FIG. 2 is a perspective view schematically showing components of the noise removing component of FIG.

The noise removing component 10 shown in these figures
In order that the ground (GND) electrode or the ground electrode 6 (hatched portion in FIG. 1) is on the outer surfaces of the bonded and integrated cores 1 and 2 and surrounds the lead frames 3 to 5, Except that they are provided so as not to come into contact with the beads 5 to 5, they have substantially the same configuration as the conventional beads 30 shown in FIG.

As shown in FIG. 1, the ground electrode 6 is provided on the upper surface, the bottom surface, and almost the entire left and right side surfaces of the substantially hexahedral noise removing component 10, but is not in contact with the lead frames 3 to 5. To prevent contact, lead frame 3 ~
5 is not provided on the front surface and the rear surface of the noise removing component 10 projecting to the outside. The ground electrode 6 is grounded by, for example, being connected to a ground pattern or the like on the printed wiring board when the noise removing component 10 is mounted on the printed wiring board. There is also.

The ground electrode 6 is formed by, for example, applying or printing a conductive paste to each of the cores 1 and 2 before assembling the noise removing component 10 and baking it as necessary. In this case, if the ground electrode 6 is formed so as to extend also to at least a part of the bonding surface where the core 1 and the core 2 are bonded, and the core 1 and the core 2 are bonded with a conductive adhesive or solder, It is more preferable because the conductivity between the ground electrodes 6 formed on the cores 1 and 2 can be reliably ensured, and the outer periphery of the noise removing component 10 can be reliably covered with the ground electrode 6. .

Also, after a magnetic material such as ferrite is electrolessly plated, cutting or cutting is performed to produce cores 1 and 2 having a ground electrode 6 formed in a predetermined region on the surface.
The noise removing component 10 can also be assembled. The ground electrode 6 may be formed by combining printing and plating. In some cases, the ground electrode 6 is connected to the noise removing component 1.
After the assembling of No. 0, it can be formed by a printing method or a plating method. If the ground electrode 6 is formed after assembling the noise removing component 10, conductivity between the ground electrodes 6 formed on the cores 1 and 2 can be easily and reliably secured.

FIG. 3 shows a schematic equivalent circuit diagram of the noise elimination component 10 of the present embodiment having such a configuration. The equivalent circuit of the noise removing component 10 is a so-called distributed constant type circuit, and functions as a distributed constant type noise filter.
Therefore, high-frequency noise can be more accurately removed as compared with the conventional beads 30 in which the ground electrode 6 is not provided on the outer peripheral portion of the core.

FIG. 4 is a graph showing frequency characteristics of the conventional example and this embodiment. A noise removing component 10 in which the ground electrode 6 is provided on almost the entire outer surface other than the surface where the lead frame protrudes as shown in FIG. 1 (corresponding to the entire surface of the ground electrode in FIG. 4)
A noise removing component (corresponding to the ground electrode half in FIG. 4) in which the width of the ground electrode 6 of the noise removing component 10 in FIG. 1 is reduced to about half and the area of the ground electrode is reduced to about half, and no ground electrode is provided. 9 shows the frequency dependence of the attenuation for each of the conventional beads 30 of FIG. 9 (corresponding to no ground electrode of FIG. 4).

Although all have an attenuation effect at 400 MHz or higher, it can be seen that the provision of the ground electrode provides extremely high attenuation in a high frequency and wide band. The effect of improving the attenuation characteristics by providing the ground electrode is particularly remarkable in a frequency band around 1 GHz to 2 GHz. Also, the larger the area of the ground electrode provided,
The effect of improving the attenuation characteristics at high frequencies is great.

The noise elimination component 10 of this embodiment has the ground electrode 6 formed on almost the entire outer surface of the noise elimination component other than the surface on which the lead frame protrudes.
Because it has high attenuation characteristics in high frequency and wide band,
High frequency noise can be more accurately removed. Also, since the structure is simple, it can be manufactured small and inexpensively.

Further, when the ground electrode 6 is provided on the entire outer surface other than the surface on which the lead frame of the noise elimination component protrudes as in this embodiment, the patterning of the pattern is more effective than the provision of the ground electrode 6 partially. The ground electrode 6 can be saved because it can save time
Is easy to form. Therefore, it is also advantageous in terms of manufacturing cost.

FIG. 5 is a perspective view showing a schematic structure of a noise removing component according to a second embodiment of the present invention. FIG. 6 is a perspective view conceptually showing each component of the noise elimination component of FIG. The noise removing component 21 shown in these figures
Unlike the noise removing component 10 shown in FIG. 1, the component is formed by a laminating method.

The noise removing component 21 of the present embodiment comprises a magnetic material 11 such as ferrite laminated and fired, and three line electrodes 12 to 1 linearly penetrating the magnetic material 11.
4. A ground electrode 15 provided on the outer surface of the magnetic body 11 so as to surround the line electrodes 12 to 14, and an input / output provided on each of the leading ends of both ends of the line electrodes 12 to 14 in the magnetic body 11. Terminal electrodes 16-18.

The terminal electrodes 16 to 18 provided on the front and rear surfaces of the magnetic body 11 are connected to both ends of the line electrodes 12 to 14, respectively, to facilitate connection to an external circuit. The ground electrode 15 is grounded by, for example, being connected to a ground pattern on the printed wiring board when the noise removing component 21 is mounted on the printed wiring board. There is also. The ground electrode 15 is connected to the terminal electrodes 16 to 16 of the magnetic body 11.
Preferably, it is formed on almost the entire outer surface other than the surface on which 18 is formed. Also, for insulation, between the terminal electrodes 16 to 18 and between the ground electrode 15 and the terminal electrode 16.
A gap is formed between.

A method for manufacturing the noise removing component 21 having such a configuration will be described. First, magnetic material powder such as ferrite is kneaded with a resin, a solvent, or the like, and magnetic sheets 19 and 20 are formed by sheet molding. Next, a conductive paste is printed on a predetermined region on the magnetic sheet 19 to form the line electrodes 12 to 14. After laminating the magnetic material sheet 20 thereon, if necessary, pressure is applied by thermocompression bonding or the like to produce a laminate.

In this case, a large number of laminated blocks may be produced by using a wide sheet for the magnetic material sheet and printing the line electrode layer in each of a large number of sections of one sheet. Further, if the magnetic sheets are laminated and then cut at a predetermined position, a large number of laminated bodies can be manufactured at once. In addition to the sheet method, for example, the magnetic material layer 19, the line electrode layers 12 to 14, and the magnetic material layer 20 may be sequentially printed by a printing method to produce a laminate block.

By firing this laminate at a predetermined temperature for a predetermined time, an integrated fired body or sintered body 11 is obtained. A conductive paste is applied or printed on a predetermined region of the surface of the obtained sintered body on the side from which the line electrodes 12 to 14 are taken out to form terminal electrodes 16 to 18, and the terminal electrodes 16 to 18 are formed.
The ground electrode 15 is formed by applying or printing a conductive paste so as not to make contact with. Further heating in the furnace,
The baking of the ground electrode 15 and the terminal electrodes 16 to 18 is performed. Thereby, the noise removing component 21 can be manufactured.

In addition to the method of forming the ground electrode 15 and the terminal electrodes 16 to 18 after the production of the sintered body, for example, the ground electrode 15 or the terminal electrodes 16 to 18 may be formed on the surface of the laminate before firing.
18 may be formed and fired together with the magnetic sheet.
Alternatively, the ground electrode layer 15, the magnetic layer 19, the line electrode layers 12 to 14, the magnetic layer 20, and the ground electrode layer 15 are sequentially printed to form a laminate block, cut and fired, and then the terminal electrode 16 To 18 may be formed. In some cases, the noise removing component 21 can be manufactured by forming a conductor layer corresponding to the ground electrode on the magnetic sheet in advance and laminating the conductor layer.

The noise removing component 21 of the present embodiment also functions as a distributed noise filter by forming the ground electrode 15 on the outer surface. Further, similarly to the noise removing component 10 of FIG. 1, high attenuation characteristics in a high frequency and a wide band can be obtained, so that high frequency noise can be accurately removed. Furthermore, since it can be manufactured by a lamination method, mass production is possible. Further, the product can be easily reduced in size, weight, surface mounting, and design change. Since the structure is simple, it can be manufactured at low cost.

FIG. 7 is a perspective view showing a schematic structure of a noise removing component according to a third embodiment of the present invention. FIG. 8 is a perspective view conceptually showing each component of the noise elimination component of FIG. The noise elimination component 25 of the present embodiment has substantially the same configuration as the noise elimination component 21 of the second embodiment described above, except that the noise elimination component 25 has the reinforcing cover 22 that covers the entire noise elimination component. Further, the present invention can also be applied to the noise removing component 10 of the first embodiment.

In general, when the number of lead frames or line electrodes is large, the L dimension of the noise removing component as shown in FIG. 7 becomes longer. If the L dimension is long, a large force is applied to both ends of the noise removing component when the noise removing component is mounted on a printed wiring board or due to the bending of the board after mounting. For this reason, the input / output terminals of the noise elimination component may be damaged, or the noise elimination component itself may be broken.

In the noise removing component 25 of the present embodiment, the reinforcing cover 22 is placed on the outer peripheral portion of the noise removing component, that is, the outer peripheral portion of the magnetic body portion 11 having the ground electrode 15 formed on the outer surface. For this reason, the mechanical strength can be increased, and damage to the noise removing component can be accurately prevented. The reinforcing cover 22 is formed by selecting a material such as a metal such as iron, ceramics, or a resin in consideration of strength and the like, and processing the material into a predetermined shape.

It is more preferable that the reinforcing cover 22 has conductivity. If the reinforcing cover 22 has conductivity, it has a shielding effect, and the ground electrode 15 on the outer surface of the magnetic body 11 should be connected to the ground pattern of the printed wiring board via the reinforcing cover 22. Can be. In FIG. 7, only the upper surface and the left and right side surfaces of the noise removing component are covered by the reinforcing cover 22, but the bottom surface and the like can be covered if necessary. The same effect can be obtained even if the reinforcing cover 22 is put on the noise removing component 10 of FIG.

Although specific embodiments have been described, the present invention provides
Any configuration is possible as long as a ground electrode is provided so as to surround a conductor penetrating the inside of the magnetic body on the outer surface of the magnetic body,
It is not limited to the above embodiment. As a method for forming the ground electrode, any of the methods commonly used for forming electrodes, such as coating, printing, and plating, can be used. Further, the present invention is not limited to the array type in which the lead frame or three line electrodes are used as one product, and the number of combinations can be set arbitrarily. The present invention can also be applied to a single noise removal component or a composite component combined with a capacitor or the like.

[0043]

As described above, according to the first to fourth aspects of the present invention, there is provided a noise elimination component or a distributed constant type noise filter having a simple structure and extremely excellent attenuation characteristics in a high frequency band. be able to.

According to the fifth to eighth aspects of the present invention, it is possible to provide a small-sized laminated component noise elimination component having extremely excellent attenuation characteristics in a high frequency band. Since it is a small laminated component, it is easy to miniaturize the product, mass-produce it, and mount it on a board.

According to the ninth aspect, the mechanical strength of the noise removing component can be improved. For this reason, it is possible to appropriately prevent damage to the noise removing component when mounting on a printed wiring board or when the board is bent.

According to the tenth aspect, the ground electrode can be connected to the ground via the reinforcing cover.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a schematic external appearance of a noise removing component according to a first embodiment of the present invention.

FIG. 2 is a perspective view schematically showing components of the noise elimination component of FIG. 1;

FIG. 3 is a schematic equivalent circuit diagram of the noise removing component of FIG.

FIG. 4 is a graph showing the frequency dependence of the attenuation.

FIG. 5 is a perspective view illustrating a schematic structure of a noise removing component according to a second embodiment of the present invention.

FIG. 6 is a perspective view conceptually showing each component of the noise elimination component of FIG. 5;

FIG. 7 is a perspective view showing a schematic structure of a noise removal component according to a third embodiment of the present invention.

FIG. 8 is a perspective view conceptually showing components of the noise removal component of FIG. 7;

FIG. 9 is a perspective view showing a schematic appearance of a conventional bead.

FIG. 10 is a perspective view schematically showing components of the conventional bead of FIG. 9;

FIG. 11 is a schematic equivalent circuit diagram of the conventional bead of FIG. 9;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 core 2 core 3 to 5 lead frame 6 ground electrode 10 noise removing component 11 magnetic material 12 to 14 line electrode 15 ground electrode 16 to 18 terminal electrode 19 magnetic material sheet 20 magnetic material sheet 21 noise removing component 22 reinforcing cover 25 noise Removal parts 30 beads

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Kuniho Watanabe 1-1-13 Nihonbashi, Chuo-ku, Tokyo Inside TDK Corporation

Claims (10)

[Claims] A bead structure including a magnetic body and at least one conductor penetrating the inside of the magnetic body; and an outer surface of the magnetic body of the bead structure, surrounding the conductor, and And a ground electrode provided so as not to contact the conductor. 2. The noise elimination component according to claim 1, wherein a plurality of conductors penetrate the inside of the magnetic body. 3. The magnetic recording medium according to claim 1, wherein the ground electrode is provided in a region of at least half of an outer surface of the magnetic body other than an end surface for taking out the conductor to the outside. Noise removal parts. 4. The magnetic recording medium according to claim 1, wherein the ground electrode is provided on substantially the entire outer surface of the magnetic body other than an end surface for taking out the conductor to the outside. Noise removal parts. 5. A laminate of at least one linear internal electrode layer and magnetic layers provided above and below the internal electrode layer, and both ends of the internal electrode layer on the outer surface of the laminate are provided. A terminal electrode provided on a surface to be respectively taken out to the outside and connected to both ends of the internal electrode layer, and on the outer surface of the laminate, surrounding the internal electrode layer, and the terminal electrode A noise removing component, comprising: a ground electrode provided so as not to come into contact with the ground electrode. 6. The noise elimination component according to claim 5, wherein the internal electrode layer includes a plurality of internal electrode layers. 7. The laminate according to claim 5, wherein the ground electrode is provided in a region of at least half of the outer surface of the laminate other than the surface on which the terminal electrodes are provided. The noise removal component described. 8. The method according to claim 5, wherein the ground electrode is provided on substantially the entire outer surface of the laminate other than the surface on which the terminal electrodes are provided. The noise removal component described. 9. The noise elimination component according to claim 5, further comprising a reinforcing cover that covers a periphery of the multilayer body having a ground electrode provided on an outer surface thereof. 10. The noise removing component according to claim 9, wherein the reinforcing cover has conductivity.