JP4630620B2 - Noise removal device - Google Patents

Description

  The present invention relates to a noise removal device for removing high-frequency noise from a signal line or the like.

  In digital devices such as mobile phones and personal computers, the signal processing speed has been increased with the increase in functionality, and there are many digital devices using a CPU whose clock frequency exceeds 1 GHz. In a digital circuit having a clock frequency exceeding several hundred MHz, high-frequency noise is generated not only in the fundamental wave band but also in a GHz band where harmonics appear. Therefore, it is necessary to remove high-frequency noise in a wide band of several hundred MHz to several GHz. .

A high-Q inductor element is generally used as a device for removing high-frequency noise, but this type of device has a characteristic that produces a much higher impedance only in a specific frequency band than in other frequency bands. Therefore, in order to remove high-frequency noise in a wide band of several hundreds of MHz to several GHz, a plurality of devices having different peak characteristics must be used in combination, increasing the burden associated with circuit design.
JP 2000-156622 A

  In the current situation as described above, the noise removal device required by circuit designers has such a characteristic that even if the peak impedance is reduced, the impedance can be sufficiently expected to have a noise removal effect in a wide frequency band. Yes, it is possible to stably obtain the targeted noise removal effect in a wide frequency band with a single device by using a device having such impedance characteristics, and greatly reduce the burden associated with circuit design. it can.

  The present invention was created in view of the above circumstances, and an object thereof is to provide a noise removal device that can stably obtain a noise removal effect in a wide frequency band with a single device. .

  In order to achieve the above object, the noise removal device of the present invention is made of a magnetic material having a resonance frequency of magnetic permeability of 100 MHz or more, and has a cross-sectional outer shape between two square column portions rather than a cross-sectional shape of the square column portion. From a core having a small shaft portion, a coil formed by winding a coil wire on the shaft portion of the core so as to have a predetermined space between the wires, and an insulating material having a lower dielectric constant than the magnetic material constituting the core Formed, covering the coil so as to be filled between the coil wires existing on the shaft portion of the core, and being formed in a quadrangular prism portion at both ends of the core, and an exterior formed so that the external shape is a quadrangular prism shape, It is characterized by comprising a pair of external electrodes in electrical communication with each end of the coil.

  According to the present invention, it is possible to stably obtain a noise removal effect in a wide frequency band with one device.

  The above object and other objects, structural features, and operational effects of the present invention will become apparent from the following description and the accompanying drawings.

  First, the structure of a noise removal device to which the present invention is applied will be described with reference to FIGS. In the following description, the left-right direction in FIG. 1 is referred to as the device length, the left-right direction in FIG. 2 as the device width, and the up-down direction in FIG. 2 as the device height.

  1 is a view of the noise removal device as viewed from one side in the width direction, FIG. 2 is a view of the noise removal device shown in FIG. 1 as viewed from one side in the length direction, and FIG. 3 is a line aa in FIG. 4 is a cross-sectional view taken along the line bb of FIG. 1, in which 10 is a device, 11 is a core, 12 is a coil, 13 is an exterior, and 14 is a pair of external electrodes.

  The core 11 is made of a magnetic material having a permeability resonance frequency of 100 MHz or more. Here, the resonance frequency is μ = μ ′ + jμ ″ (μ is the magnetic permeability, μ ′ is a real component of the magnetic permeability that can follow the magnetic field, and jμ ″ is an imaginary component of the magnetic permeability that can not follow the magnetic field and is delayed by 90 degrees). In the equation, the frequency at which the imaginary component jμ ″ of the magnetic permeability reaches a peak.

As a magnetic material having a magnetic resonance resonance frequency of 100 MHz or more, Ni—Zn spinel ferrite, Y-type or Z-type hexagonal ferrite having a resonance frequency higher than that of spinel ferrite, and the like can be preferably used. In addition, Ni—Zn—Cu based spinel ferrite may be used for adjusting the sinterability, and the sinterability can be adjusted by adding Bi ₂ O ₃ , SiO ₂ or the like. Furthermore, an oxide such as CoO, Mn ₂ O ₃ , MgO, or Cr ₂ O ₃ may be added to finely adjust the characteristics.

Ni-Zn spinel ferrite can be adjusted in magnetic permeability and frequency characteristics by adjusting the composition such as Fe ratio and Ni / Zn ratio. The preferred Fe ratio in the case of using the Ni-Zn-based spinel ferrite is 40 mol% or more as Fe ₂ O _3, loss of Fe ratio exceeds 49.5 mol% is increased, and is less than 46 mol% permeability Therefore, it is desirable to use a material having an Fe ratio in the range of 46 to 49.5 mol%. The resonance frequency can be changed by the Ni / Zn ratio, and the resonance frequency can be increased by increasing the Ni / Zn ratio. A preferable Ni / Zn ratio is 1 or more, but it is desirable to use a Ni / Zn ratio of 4 or more.

  The magnetic material constituting the core 11 is a composite magnetic material in which a predetermined amount of the ferrite magnetic powder or other magnetic powder is contained in a nonmagnetic inorganic insulator or nonmagnetic organic insulator. It can also be used. Incidentally, when the resonance frequency of the magnetic permeability is not 100 MHz, sufficient impedance characteristics cannot be obtained in the high frequency band.

  Further, the core 11 has two rectangular column parts 11a symmetrically at both ends, and a shaft part 11b having a smaller sectional outline than that of the rectangular column part 11a is coaxially disposed between the two rectangular column parts 11a. Have on. The cross sections of the two quadrangular columnar portions 11a are square or have a shape similar thereto, and the cross section of the shaft portion 11b is circular or have a shape approximate to this. In the drawing, the boundary surface between the two quadrangular columnar portions 11a and the shaft portion 11b is formed by a surface orthogonal to the center line of the core 11, but the boundary surface is a surface that forms an acute angle with the center line of the core 11. Three-dimensionally, it may be formed in a truncated cone shape whose outer shape gradually decreases from the quadrangular prism portion 11a toward the shaft portion 11b. Moreover, the recessed part 11a1 in which a cross section forms trapezoid shape or a rectangular shape is provided in the bottom face of the two square pillar parts 11a along the length direction. There are no particular restrictions on the length of the two quadrangular columnar portions 11a and the length of the shaft portion 11b of the core 11, but the length of the shaft portion 11b is a length that allows the coil 12 to be configured with a predetermined number of turns and pitch. Can be secured. Further, the diameter D of the shaft portion 11b of the core 11 is within a range of 0.3T <D <0.9T, preferably 0.5T, where T is the height of the rectangular column portion 11a at both ends of the core. Like that.

  The coil 12 is made of a wire in which a conductive wire is covered with an insulating material, and is configured by winding the coil wire on the shaft portion 11 b of the core 11 a predetermined number of times. The conductive wire of the coil wire can be used as long as it has a predetermined resistivity, but Cu-based, Ni-based, and Ag-based wires are preferably used. Any insulating material for the coil wire can be used as long as it has insulating properties, but plastics such as polyurethane and polyester are preferably used.

Moreover, the coil wire which comprises the coil 12 is not wound closely, but is wound so that there may be a predetermined space between the wires (space winding). The number N of turns of the coil 12 is in the range of B / {A + (A / 2)} ≧ N ≧ B / 3A, where B is the length of the shaft portion 11b and A is the diameter of the conductive wire of the coil wire. It is preferable to be within. The space between the coils 12 is set to 1/2 to 3 times the diameter of the coil wire, and preferably 0.8 times the diameter of the coil wire.

  Furthermore, the one end 12a of the coil 12 is inserted into the recess 11a1 of one square column 11a and flattened so as to match the depth of the recess 11a1, and the other end 12a is formed on the other square column 11a. It is inserted into the recess 11a1 and crushed flat so as to match the depth of the recess 11a1.

  The exterior 13 is made of an insulating material, covers the coil 12 so as to be filled between the wires of the coil 12 existing on the shaft portion 11b, and is formed so that the external shape is a quadrangular prism shape. Are parallel to or approximate to the four side surfaces of the quadrangular prism portion 11a. The exterior 13 is made of an insulating material having a dielectric constant smaller than that of the magnetic material constituting the core 11, and specifically, Ni—Zn spinel ferrite powder, Mn—Zn spinel ferrite powder, hexagonal ferrite powder, metal magnetic powder. It is made of a magnetic powder-containing plastic in which at least one of them is contained in an insulating plastic material such as an epoxy resin in an amount of 30 to 90 wt%, preferably 65 wt%. For the metal magnetic powder, permalloy, sendust, pure iron or the like can be suitably used. In this case, in order to obtain the smoothness of the exterior surface, it is preferable to use the one having a maximum particle size of 20 μm or less, more preferably metal. A magnetic powder having an oxide film formed on the surface thereof is used.

  The pair of external electrodes 14 is formed with a substantially uniform thickness so as to continuously cover a part of the bottom surface and the end surface of each quadrangular column portion 11 a, and each external electrode 14 is electrically connected to each end portion 12 a of the coil 12. Is conductive. In consideration of the case where the device 10 is mounted on a substrate or the like, the bottom surface portion of each external electrode 14 protrudes downward from the bottom surface portion of the exterior 13. Each external electrode 14 is made of a metal such as Ag, Cu, Ni, Sn, or an alloy thereof, and has a single layer or a multilayer structure. There is no particular limitation on the thickness of the external electrode 14. The external electrode 14 may be continuously provided on the end surface of each square column portion 11a and four surfaces adjacent to the end surface, but preferably, the bottom surface of each square column portion 11a and a part of the end surface are continuously provided. The height of the portion that wraps around the end face is set to 1/4 to 1/2 of the height of the quadrangular prism portion 11a.

  5 to 10 show various verification data when the above-described device 10 is created in 1608 size (reference values of length, width, and height are 1.6 mm, 0.8 mm, and 0.8 mm), respectively. FIG. 11 shows the impedance characteristics of the device.

FIG. 5 shows verification data of the core material. Here, the core 11 has a composition ratio of 47 mol% of Fe ₂ O ₃ , 40 mol% of NiO, 2 mol% of ZnO, and 6 mol% of CuO. The impedance characteristic of a ferrite (magnetic material having a magnetic permeability resonance frequency of 100 MHz or more) is shown by a solid line, and the impedance characteristic of a core 11 made of alumina not containing ferrite powder is shown by a broken line.

  As can be seen from FIG. 5, when the core 11 is made of alumina containing no ferrite powder (see the broken line), the core 11 shows a strong impedance characteristic in which the impedance rapidly increases in the vicinity of 7.5 GHz. In the case of the Ni—Zn-based spinel ferrite (see solid line), resonance points appear at two locations near 3.0 GHz and 9.0 GHz, and a relatively flat impedance characteristic is exhibited in a wide frequency band.

  FIG. 6 shows verification data of the diameter of the shaft portion of the core 11. Here, the impedance characteristic of the shaft portion 11b having a diameter of 0.5T (T is the height of the quadrangular column portion 11a) is represented by a solid line. The impedance characteristic of the portion 1b having a diameter of 0.9T or more is shown by a solid line. Incidentally, in the 1608 size, the reference value of the height T of the quadrangular columnar portion 11a is 0.8 mm, so the shaft diameter in the case of 0.5T is 0.4 mm, and the shaft diameter in the case of 0.9T is 0. 72 mm.

  As can be seen from FIG. 6, when the shaft 11b has a diameter of 0.9T or more (see the broken line), the impedance suddenly increases near 1.0 GHz, but the shaft 11b has a diameter of 0. In the case of .5T (see solid line), resonance points appear at two locations near 3.5 GHz and 9.0 GHz, and a relatively flat impedance characteristic is exhibited in a wide frequency band.

  FIG. 7 shows the verification data of the winding form of the coil 12. Here, a coil wire having a diameter of 50 μm is wound with 6 turns so that a space between wires of 40 μm (= 50 μm × 0.8) is vacant. The impedance characteristic of the thing is represented by a solid line, and the impedance characteristic of the same coil wire rod that is closely wound with 6 turns so that the space between the wires is zero is represented by a broken line.

  As can be seen from FIG. 7, the closely wound type (see the broken line) shows the impedance characteristic where the resonance point appears near 1.5 GHz, but the space wound type (see the solid line) shows the vicinity of 1.5 GHz and around 8.5 GHz. Resonance points appear at two locations and a relatively flat impedance characteristic in a wide frequency band.

  FIG. 8 shows verification data of the number of turns of the coil 12. Here, the impedance characteristic of the coil 12 having 8 turns is represented by a solid line, and the impedance characteristic of the coil 12 having 4 turns is represented by a broken line. It is represented.

  As can be seen from FIG. 8, when the number of turns is 4 (see the broken line), resonance points appear at two locations near 3.0 GHz and 9.5 GHz, but the impedance increases rapidly around 9.5 GHz. The characteristic is shown, but when the number of turns is 8 (see solid line), resonance points appear at two places near 3.0 GHz and 9.0 GHz, and a relatively flat impedance characteristic is shown in a wide frequency band.

  FIG. 9 shows the verification data of the exterior material. Here, the impedance characteristics of the exterior 13 made of an epoxy resin containing 65 wt% of the same Ni—Zn spinel ferrite powder as the core 11 are represented by a solid line, and the ferrite powder is contained. Impedance characteristics of the non-epoxy resin are represented by broken lines.

  As can be seen from FIG. 9, the package 13 made of an epoxy resin containing a ferrite powder ratio (see the broken line) shows a strong impedance characteristic in which the impedance rapidly increases in the vicinity of 9.5 GHz. In the case of the epoxy resin containing (see solid line), resonance points appear at two locations near 2.0 GHz and 8.0 GHz, and a relatively flat impedance characteristic is exhibited in a wide frequency band.

  FIG. 10 shows verification data of the electrode configuration. Here, the external electrode 14 is provided so as to continuously cover the bottom surface and a part of the end surface of each quadrangular columnar portion 11a, and the height of the portion that wraps around the end surface is shown. The impedance characteristic of the rectangular column portion 11a that is 3/8 of the height is represented by a solid line, and the impedance of the external electrode 14 provided continuously on the end surface of each square column portion 11a and the four surfaces adjacent to the end surface is shown. The characteristic is represented by a broken line. Incidentally, in the 1608 size, the reference value of the height of the quadrangular columnar portion 11a is 0.8 mm, so that the height of the wraparound portion when the height is 3/8 is 0.3 mm.

  As can be seen from FIG. 10, each of them has similar impedance characteristics in which resonance points appear at two locations near 3.0 GHz and 8.0 GHz, but the external electrode 14 has a bottom surface and an end surface of each square column portion 11a. The one provided continuously in a part (see solid line) can obtain a high impedance in a wide frequency band.

FIG. 11 shows each component adopted in the data verification of FIGS.
Core material: Fe ₂ O ₃ of 47 mol%, NiO of 40 mol%, 2 mol% of ZnO, Ni-Zn-based spinel ferrite shank diameter and the C uO and 6 mol% composition ratio: 0.4 mm
-Winding form: Space winding and the number of windings: 8 so that the space between the wires of the coil wire 50mm in diameter is 40μm.
-Exterior material: Epoxy resin containing 65 wt% of Ni-Zn-based spinel ferrite powder-Electrode form: The height of the portion that wraps around the end face in a form that continuously covers the bottom face and part of the end face of each square pillar 11a Is 0.3mm
The impedance characteristic of the device 10 of 1608 size configured by combining

  As can be seen from FIG. 11, the device 10 does not have a characteristic that generates a much higher impedance than the other frequency bands only in a specific frequency band, and has two locations near 3.0 GHz and 8.0 GHz. Since it has an impedance characteristic that shows a gentle gradient in a wide band of several hundreds of MHz to several GHz with a resonance point appearing in a single device, it is possible to stably obtain the desired noise removal effect in a wide frequency band with one device It is.

  The basis for the appearance of such an impedance characteristic is not clear, but it goes without saying that the basic structure of the device 10 itself described with reference to FIGS. 1 to 4 is involved, and FIGS. It is thought that each component explained in the above is involved. Therefore, when the same device as the device 10 is produced in another size, for example, 1005 size (reference values of length, width, and height are 1.0 mm, 0.5 mm, and 0.5 mm) or 0603 size ( Even when the standard values of length, width, and height are 0.6 mm, 0.3 mm, and 0.3 mm), the same effect can be obtained by adopting the same basic structure and each component. Is possible.

  1 to 4, the shaft 11b of the core 11 has a circular cross-sectional outer shape. However, as shown in FIG. 12, the cross-sectional outer shape of the quadrangular column 11a is between two rectangular columns 11a. The core 11 may have a shaft section 11b ′ having a smaller cross-sectional outer shape and having a square cross section or a shape similar to this. In this case, since the coil 12 is formed by winding the coil wire on the shaft portion 11b ', the design philosophy relating to the diameter of the shaft portion 11b may be applied to the diameter of the inscribed circle of the shaft portion 11b'.

It is the figure which looked at the noise removal device to which this invention is applied from the one surface side of the width direction. It is the figure which looked at the noise removal device shown in FIG. 1 from the one surface side of the length direction. It is the sectional view on the aa line of FIG. It is the bb sectional view taken on the line of FIG. It is a figure which shows the verification data of a core material. It is a figure which shows the verification data of the axial part diameter of a core. It is a figure which shows the verification data of the coil | winding form of a coil. It is a figure which shows the verification data of the winding number of a coil. It is a figure which shows the verification data of an exterior material. It is a figure which shows the verification data of an electrode form. It is a figure which shows the impedance characteristic of the device of 1608 size comprised combining each component employ | adopted by the data verification of FIGS. It is the figure which looked at the noise removal device which made the axial part shown in FIGS. 1-4 the square pillar shape from the one surface side of the length direction.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Device, 11 ... Core, 11a ... Quadratic prism part, 11b, 11b '... Shaft part, 12 ... Coil, 13 ... Outer casing, 14 ... One pair of external electrodes.

Claims (5)

A core made of a magnetic material having a resonance frequency of magnetic permeability of 100 MHz or more, and having a shaft portion between two square column portions, the shaft portion having a smaller cross-sectional shape than the cross-sectional shape of the square column portion;
A coil configured by winding a coil wire on the shaft portion of the core so as to have a predetermined space between the wires;
It is made of an insulating material whose dielectric constant is smaller than that of the magnetic material that makes up the core. The coil is covered so that it is filled between the wires of the coil existing on the shaft part of the core, and the external shape is a quadrangular prism. The exterior,
A pair of external electrodes formed on the rectangular pillars at both ends of the core and electrically connected to each end of the coil ;
A resonance point appears at two different frequencies in the GHz band, and has an impedance characteristic showing a gentle gradient in a high frequency band including the GHz band.
A noise removing device characterized by that. The outer package is made of a plastic containing magnetic powder containing 30 to 90 wt% of at least one of Ni—Zn spinel ferrite powder, Mn—Zn spinel ferrite powder, hexagonal ferrite powder, and metal magnetic powder.
The noise removal device according to claim 1. The cross section of the shaft portion of the core is circular or quadrangular, and the diameter D is 0 when the diameter of the circular cross section or the diameter of the inscribed circle of the cross sectional quadrangle is D and the height of the square pillars at both ends of the core is T. In the range of 3T <D <0.9T,
The noise removal device according to claim 1 or 2, characterized in that When the number of turns of the coil is N, the length of the shaft portion of the core is B, and the diameter of the conductive wire of the coil wire is A, the number of turns N is B / {A + (A / 2)} ≧ N ≧ Within the range of B / 3A,
The noise removal device according to claim 1 or 2, characterized in that The pair of external electrodes has a form continuously covering the bottom surface and part of the end surface of the quadrangular column at both ends of the core.
The noise removal device according to claim 1 or 2, characterized in that

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