JP2022172333A - inductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide high performance inductors with a low resistance and a high Q value, which can reduce the size and thickness of an inductor in a power supply component such as high-frequency DC/DC converter to reduce a high-frequency loss due to the skin effect and proximity effect of a coil.

SOLUTION: In an inductor having a coil with a wound conductor wire having a coil conductor portion with a rectangular cross section and a magnetic body covering the coil, a non-magnetic insulator is disposed at a position corresponding to a central portion of one or both of long sides of the rectangular cross section between the non-magnetic insulator and the magnetic body in at least one of the coil conductor portions, Further, at both ends of the coil conductor portion, the magnetic body is in contact with the coil conductor portion and covers the coil conductor portion.

SELECTED DRAWING: Figure 3

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present invention relates to inductors used in electronic circuits, and more particularly to inductors used in power supply components such as DC/DC converters.

2. Description of the Related Art In recent years, the miniaturization of electronic devices typified by notebook computers and mobile phones has progressed, and the demand for compact power sources such as DC/DC converters is increasing. Along with this, the size and weight of inductors to be mounted are also being reduced, and planar/thin-film inductors and multilayer chip-type compact inductors using semiconductor manufacturing technology and micromachining technology are being studied.

A conventional inductor has a structure in which a magnetic body covers a conductor portion of a coil, as described in Patent Document 1 and Patent Document 2, for example. This is because the magnetic shielding effect of the magnetic material allows the magnetic material to avoid the magnetic flux that interlinks with the coil conductor, and suppresses the occurrence of eddy currents due to the skin effect and proximity effect inside the coil conductor, thereby reducing copper loss. It is for

Japanese Patent Application Laid-Open No. 2001-267155 Japanese Patent Application Laid-Open No. 2003-347122

However, when the DC/DC converter is operated at a high frequency, the relative magnetic permeability of the magnetic material decreases, and magnetic flux tends to leak from the magnetic material to the coil in conventional inductors. For this reason, there has been a problem that the AC resistance is large due to the copper loss, and a high Q value cannot be obtained.

Therefore, in view of the above circumstances, the present invention makes it possible to reduce the size and thickness of inductors in power supply parts such as high-frequency DC/DC converters, reduce high-frequency loss due to the skin effect and proximity effect of coils, and reduce resistance. It is an object of the present invention to provide a high-performance inductor with a high Q value.

An inductor according to a first aspect of the invention is an inductor having a coil around which a conductor wire having a rectangular cross section is wound and a magnetic material covering the coil, wherein at least one of the coil conductors includes the magnetic A non-magnetic insulator is provided at a position corresponding to the central portion of one or both of the long sides of the rectangular cross section between the coil conductor and the magnetic body at both ends of the coil conductor. It is characterized in that it has a structure covering the coil conductor portion in contact therewith.

According to a second invention, in the inductor according to the first invention, the coil is a planar spiral coil wound in a spiral shape.

According to a third aspect of the invention, in the inductor according to the first aspect of the invention, the coil is a spirally wound flat wound coil.

According to a fourth invention, in the inductor according to the first invention, the coil is a spirally wound helical coil.

According to a fifth aspect of the invention, in the inductor according to the first aspect of the invention, the coil is formed on a flexible substrate.

The inductor according to a sixth invention is the inductor according to any one of the first to fifth inventions, wherein the width of the non-magnetic insulator in the long side direction of the rectangular cross section of the coil conductor portion is the rectangle of the coil conductor portion. It is characterized by being 0.4 times or more and less than 1 time the length of the long side of the cross section.

According to a seventh invention, in the inductor according to the first invention, the coil conductor portion has a laminated structure of a conductor and an insulator.

According to the first to fourth inventions, the non-magnetic insulator is provided between the coil conductor and the magnetic body on at least one long side of the rectangular cross section of the coil conductor, so that the magnetic body is connected to the coil. Magnetic flux leakage, especially magnetic flux leakage to the edge portion of the coil conductor can be suppressed. Therefore, it is possible to suppress the generation of eddy current inside the coil conductor and reduce the copper loss due to the skin effect and the proximity effect. Thereby, AC resistance can be lowered and a high Q value can be obtained.

According to the fifth invention, by forming the coil on the flexible substrate, the size and thickness of the inductor can be easily reduced.

According to the inductor of the sixth invention, by setting the width of the non-magnetic insulator within a predetermined range (0.4 to 1 times the width of the coil conductor), the non-magnetic insulator can be A higher Q value can be obtained than a conventional inductor without a magnetic insulator.

According to the inductor of the seventh aspect of the invention, the coil conductor portion has a laminated structure of conductors and insulators, and the coil conductor portion is formed of a plurality of conductor portions, thereby further suppressing the effects of eddy currents due to the skin effect and the proximity effect. be able to.

FIG. 2 is a schematic plan view of coils of inductors according to first, second and third embodiments (portions of magnetic bodies and non-magnetic insulators are omitted). 1 is a schematic cross-sectional view of an inductor according to a first embodiment; FIG. It is a cross-sectional schematic diagram of an inductor according to a second embodiment. It is a cross-sectional schematic diagram of an inductor according to a third embodiment. It is a figure (plan view) explaining the analysis model of a coil. It is a calculation result of inductor characteristics (dw dependence of AC resistance R) according to the third embodiment. It is a calculation result of inductor characteristics (dw dependence of inductance L) according to the third embodiment. FIG. 10 is a calculation result of inductor characteristics (dw dependence of Q value) according to the third embodiment; FIG. It is a calculation result of inductor characteristics (dt dependence of AC resistance R) according to the third embodiment. It is a calculation result of inductor characteristics (dt dependency of inductance L) according to the third embodiment. FIG. 10 is a calculation result of inductor characteristics (dt dependence of Q value) according to the third embodiment; FIG. Schematic top view of a coil of an inductor according to a fourth embodiment (portions of magnetic bodies and non-magnetic insulators are omitted) Cross-sectional schematic diagram of an inductor according to a fourth embodiment Schematic top view of coil of inductor according to fifth embodiment (portions of magnetic material and non-magnetic insulator are omitted) Cross-sectional schematic diagram of an inductor according to a fifth embodiment Calculation results of inductor characteristics (dw dependence of AC resistance R) according to the fifth embodiment Calculation results of inductor characteristics (dw dependence of inductance L) according to the fifth embodiment Calculation results of inductor characteristics (dw dependence of Q value) according to the fifth embodiment It is a figure explaining the manufacturing process of the inductor of an Example. 4A and 4B are photographs of conductors, composite cores and inductors of examples. 1 is a schematic diagram of the right side of a cross-section of an example inductor; FIG. 4 is a photograph of a composite core of a comparative example; It is a schematic diagram of the right side of the cross section of the inductor of the comparative example. It is the frequency characteristic of the AC resistance R of the example and the comparative example. It is the frequency characteristic of the inductance L of an example and a comparative example. It is the frequency characteristic of the Q value of the example and the comparative example.

Hereinafter, inductors according to embodiments of the present invention will be described based on the drawings, but the present invention is not limited to the embodiments described here.
<First Embodiment>

FIG. 1 is a schematic plan view of only coil portions of inductors according to first, second and third embodiments. Portions of the magnetic material and the non-magnetic insulator are omitted and not shown. The coil is a planar spiral coil in which a conductor wire having a coil conductor portion 1 with a rectangular cross section is spirally wound. Although the number of coil turns is 4, it is not limited to this number of turns. The conductor wire may be not only a rectangular wire but also a litz wire obtained by twisting a plurality of wires and having a substantially rectangular cross section. The coil is made of a metal such as aluminium, copper or Manganin® (an alloy of copper, manganese and nickel).

FIG. 2 is a schematic cross-sectional view of the inductor according to the first embodiment. A magnetic body 2 and a non-magnetic insulator 3 are added to the AA' section of FIG. The coil conductor portion 1 is covered with the magnetic material 2. A non-magnetic insulator is placed in contact with the surface of the upper long side of the coil conductor portion 1, that is, between the coil conductor portion 1 and the magnetic material 2 on the upper surface of the coil. 3 are placed. In this embodiment, the non-magnetic insulator 3 is arranged between all the coil conductors 1 and the magnetic body 2 on the upper surface of the coil. It may be arranged between bodies 2 . Since it is a spiral coil, the long side direction of the rectangular cross section of the coil conductor portion 1 is perpendicular to the z-axis direction, ie, coincides with the radial direction (r direction). Therefore, the width of the nonmagnetic insulator in the long side direction of the rectangular cross section of the coil conductor corresponds to the radial width of the coil, and the length of the long side of the rectangular cross section of the coil conductor corresponds to the radial width of the coil. Equivalent to. The width of the nonmagnetic insulator in the long side direction of the rectangular cross section of the coil conductor portion is equal to or less than the length of the long side of the rectangular cross section of the coil conductor portion. ) is less than or equal to the width of the coil of the coil conductor portion 1 in the radial direction (r direction). The magnetic body 2 can be made of a magnetic composite material containing iron-based amorphous magnetic powder such as FeSiCrB, ferrite, electromagnetic steel sheet, sendust, permalloy, Ni-based or Fe-based ferromagnetic material, or the like. The non-magnetic insulator 3 can be composed of SiO2, alumina, polymeric resin material, or a gas such as air or argon. Here, a non-magnetic insulator means an insulating substance that is not ferromagnetic but paramagnetic or diamagnetic and has a resistivity of 10 ⁸ Ωm or more.

In the first embodiment, the magnetic material 2 is filled and arranged between the coil conductor portions 1 and 1 . As a result, the magnetic flux at both ends of the coil conductor portion 1 is attracted to and induced by the magnetic material 2 having a high relative magnetic permeability, and magnetic flux concentration at both ends of the coil conductor portion 1 can be avoided. Further, a magnetic body 2 is arranged on the coil conductor portion 1 with a non-magnetic insulator 3 interposed therebetween. As a result, the distance between the magnetic bodies 2 facing each other through the coil conductor portion 1 is increased, and the magnetic resistance is increased. Therefore, in the first embodiment, due to the action described above, it is possible to suppress the generation of eddy currents in the coil, suppress the increase in AC resistance, and obtain a high Q value.

At this time, the width of the coil of the non-magnetic insulator 3 in the radial direction (r direction) is preferably 0.4 to 1 times the width of the coil of the coil conductor portion 1 in the radial direction (r direction). This is because a high Q value can be obtained.

Also, the coil may be formed on a non-magnetic substrate. At this time, the substrate can be a flexible substrate in order to obtain impact resistance.

Furthermore, the coil conductor portion 1 may be composed of a laminated structure of a conductor and an insulator. This is because the effects of eddy currents due to the skin effect and proximity effect can be suppressed.
<Second Embodiment>

FIG. 3 is a schematic cross-sectional view of an inductor according to a second embodiment. A magnetic body 2, a first non-magnetic insulator 31 and a second non-magnetic insulator 32 are added to the AA' section of FIG. In comparison with the first embodiment, the first non-magnetic insulator 31 and the second non-magnetic insulator 32 are arranged on both long sides (sides perpendicular to the z-axis) of the cross section of the coil conductor portion 1. there is That is, the second nonmagnetic insulator 32 is arranged between the coil conductor portion 1 and the magnetic body 2 not only on the first nonmagnetic insulator 31 on the upper surface of the coil but also on the lower surface. The widths in the radial direction (r direction) of the coil of the first nonmagnetic insulator 31 and the second nonmagnetic insulator 32 arranged on the upper and lower surfaces of the coil are both ). The magnetic body 2 can be made of a magnetic composite material containing iron-based amorphous magnetic powder such as FeSiCrB, ferrite, electromagnetic steel sheet, sendust, permalloy, Ni-based or Fe-based ferromagnetic material, or the like.

In the second embodiment, the first non-magnetic insulator 31 and the second non-magnetic insulator 32 are arranged on both the top surface and the bottom surface of the coil conductor portion 1, respectively. The distance between the magnetic bodies 2 facing each other via the magnetic insulator 31 and the second non-magnetic insulator 32 is further increased compared to the first embodiment, and the magnetic resistance is increased. As a result, magnetic flux leakage from the magnetic body 2 at the central portion of the coil conductor portion 1 can be reduced, an increase in AC resistance can be suppressed, and a higher Q value can be obtained.

At this time, the widths in the radial direction (r direction) of the coil of the first nonmagnetic insulator 31 and the second nonmagnetic insulator 32 arranged on the upper surface and the lower surface of the coil are both It is preferably 0.4 to 1 times the width in the (r direction). This is because a high Q value can be obtained.

Also, the coil may be formed on a non-magnetic substrate, and the coil conductor portion 1 may have a laminated structure of a conductor and an insulator.
<Third Embodiment>

FIG. 4 is a schematic cross-sectional view of an inductor according to a third embodiment. A magnetic body 21, a magnetic body 22, a first non-magnetic insulator 31, a second non-magnetic insulator 32 and a substrate 4 are added to the AA' section of FIG. In the inductor according to the third embodiment, the substrate 4 is inserted between the magnetic bodies 21 and 22 in addition to the second embodiment. It has a structure in which the body is divided into two parts, the magnetic body 21 and the magnetic body 22 , and the magnetic body 21 and the magnetic body 22 face each other with the substrate 4 interposed therebetween.

In FIG. 4, the magnetic body 21 and the magnetic body 22 are composed of a magnetic composite material containing iron-based amorphous magnetic powder such as FeSiCrB, ferrite, electromagnetic steel sheet, sendust, permalloy, Ni-based, Fe-based ferromagnetic materials, etc. be able to. The non-magnetic insulator 31 and the non-magnetic insulator 32 can be made of SiO2, alumina, polymeric resin material, or the like. Further, the substrate 4 is non-magnetic (paramagnetic or diamagnetic instead of ferromagnetic), and is flexible and made of a plastic material such as polyimide or polyethylene terephthalate (PET) in order to secure impact resistance and facilitate handling. It can be a substrate.

The widths of the first nonmagnetic insulator 31 and the second nonmagnetic insulator 32 in the radial direction (r direction) of the coil of the coil conductor portion 1 are both the same as in the second embodiment. ). Preferably, the width of the coil of the first nonmagnetic insulator 31 and the second nonmagnetic insulator 32 in the radial direction (r direction) is the width of the coil of the coil conductor portion 1 in the radial direction (r direction). 0.4 to 1 times.

Furthermore, the coil conductor portion 1 may be composed of a laminated structure of a conductor and an insulator.
(Electromagnetic field analysis)

In order to explain the effect of the third embodiment, calculation results of electromagnetic field analysis by the finite element method will be explained. As software for electromagnetic field analysis, electromagnetic field analysis software ANSYS Maxwell (manufactured by ANSYS) was used to calculate inductor characteristics (AC resistance R, inductance L, Q value). Table 1 summarizes the analysis conditions.

FIG. 5 is a diagram (plan view) for explaining an analysis model of the coil. However, the magnetic material, the non-magnetic insulator and the substrate are omitted and not shown. The coil conductor is assumed to be a copper material with a resistivity of 1.72×10 ⁻⁸ Ωm. It is a spiral planar coil with four turns. The outer diameter (diameter) OD of the coil is 22.4 mm, the inner diameter (diameter) ID is 3.4 mm, the pitch is 0.5 mm, the width of the coil conductor in the radial direction of the coil is 2 mm, and the thickness of the coil conductor 1 is 70 μm.

FIG. 4 corresponds to the AA' cross-sectional view of FIG. Although the magnetic material, the non-magnetic insulator and the substrate are omitted in FIG. 5, the magnetic material, the non-magnetic insulator and the substrate are additionally shown in FIG. 4 in addition to the coil. In FIG. 4, the film thickness of the substrate 4 is 37 μm (=film thickness of the substrate itself 25 μm+adhesive layer 12 μm), the film thicknesses of the first magnetic body 21 and the second magnetic body 22 are equal, and the coil conductor portion 1 and the first magnetic body 21, the second magnetic body 22, the non-magnetic insulator 31, the non-magnetic insulator 32 and the substrate 4 have a total thickness of 0.8 mm. Furthermore, in FIG. 4, both the widths in the radial direction (r direction) of the coils of the first nonmagnetic insulator 31 and the second nonmagnetic insulator 32 are set to "dw", and the first nonmagnetic insulator 31 and the second 2 The thickness of the non-magnetic insulator 32 is also equal and set to "dt".

6 to 8 are calculation results of the dw dependence of the AC resistance R, inductance L and Q value of the inductor according to the third embodiment, respectively. 9 to 11 are the calculation results of the dt dependence of the AC resistance R, inductance L and Q value of the inductor according to the third embodiment.

From FIGS. 6 to 8, as dw increases, the inductance L decreases, but the AC resistance R also decreases and the Q value increases. is larger than when dw=0 mm. Further, from FIG. 8, when dw is 0.4 to 1 times the width of the coil conductor portion 1 (when dw is 0.8 mm or more and 2 mm or less), the Q value for any dt is dw= It is larger than when it is 0 mm.

Moreover, when dt is 0.1 mm or more, the Q value becomes maximum for each dt when dw is around 1.8 mm. This corresponds to the case where the first magnetic body 21 and the second magnetic body 22 cover both ends of the coil conductor portion 1 by approximately 0.1 mm.
<Fourth Embodiment>

FIG. 12 is a schematic top view of only the coil portion of the inductor according to the fourth embodiment. Portions of the magnetic material and the non-magnetic insulator are omitted and not shown. The coil is a coil in which a conductor wire having a coil conductor portion 1 with a rectangular cross section is spirally wound. , is a flat-wound coil in which the long side of the rectangular cross section of the coil conductor portion 1 is parallel to the z-axis. A flat-wound coil is formed by winding a conductor wire (coil conductor portion 1) having a rectangular cross section so as to be laminated in the radial direction, but the conductor wire (coil conductor portion) is not limited to a rectangular wire. The conductor wire may be a Litz wire having a substantially rectangular cross section. The coil is made of a metal such as aluminium, copper or Manganin® (an alloy of copper, manganese and nickel).

FIG. 13 is a schematic cross-sectional view of an inductor according to a fourth embodiment. A magnetic body 2 and a non-magnetic insulator 3 are added to the AA' cross section of FIG. Although the number of coil turns is 4, it is not limited to this number of turns. A magnetic body 2 covers the coil conductor portion 1 , and a non-magnetic insulator 3 is arranged between the innermost and outermost peripheral surfaces of the coil and the magnetic body 2 .

In this embodiment, a non-magnetic insulator 3 is inserted between the magnetic body 2 and is in contact with the inner peripheral surface of the innermost coil conductor portion 1 and the outer peripheral surface of the outermost coil conductor portion 1. there is The width of the nonmagnetic insulator 3 in the long side direction (z-axis direction) of the rectangular cross section of the coil conductor portion 1 is equal to or less than the length of the long side of the rectangular cross section of the coil conductor portion. At this time, the width of the non-magnetic insulator 3 is preferably 0.4 to 1 times the length of the long side of the coil conductor. This suppresses leakage of magnetic flux from the magnetic material to the coil conductor at the innermost and outermost circumferences of the coil, suppresses the generation of eddy current inside the coil conductor, The loss can be reduced and the Q factor can be increased. Note that the coil conductor portion 1 may have a laminated structure of a conductor and an insulator.

The arrangement of the non-magnetic insulators 3 is not limited to that of this embodiment. For example, the non-magnetic insulator 3 is arranged between the coil conductor 1 and the magnetic body 2 in contact with not only the innermost and outermost circumferences of the coil, but also the other part of the long side of the coil conductor 1. may be It may also be arranged between all coil conductor portions. The magnetic body 2 can be made of a magnetic composite material containing iron-based amorphous magnetic powder such as FeSiCrB, ferrite, electromagnetic steel sheet, sendust, permalloy, Ni-based or Fe-based ferromagnetic materials, and the like. The non-magnetic insulator 3 can be composed of SiO2, alumina, polymer resin material, or a gas such as air or argon.
<Fifth Embodiment>

FIG. 14 is a schematic top view of only the coil portion of the inductor according to the fifth embodiment. Portions of the magnetic material and the non-magnetic insulator are omitted and not shown. The coil is a helical coil in which a conductor wire having a coil conductor portion 1 with a rectangular cross section is spirally wound. When the conductor wire is a flat wire, the helical coil is also called an edgewise coil, but the conductor wire (coil conductor portion) is not limited to the flat wire. The conductor wire may be a Litz wire having a substantially rectangular cross section. The coil is made of a metal such as aluminium, copper or Manganin® (an alloy of copper, manganese and nickel).

FIG. 15 is a schematic cross-sectional view of an inductor according to a fifth embodiment. A magnetic body 2 and a non-magnetic insulator 3 are added to the AA' cross section of FIG. Although the number of coil turns is 4, it is not limited to this number of turns. The coil conductor portion 1 is covered with the magnetic material 2, and the third non-magnetic insulator 33 is inserted and arranged between the magnetic material 2 on the top surface and the bottom surface of the coil. A fourth non-magnetic insulator 34 is also arranged between the coil conductors.

In the helical coil of FIG. 15, the long side direction of the rectangular cross section of the coil conductor portion 1 coincides with the direction perpendicular to the z-axis, that is, the radial direction (r direction). On the top and bottom surfaces of the coil, the width of the third non-magnetic insulator 33 in the long side direction (radial direction perpendicular to the z-axis) of the rectangular cross section of the coil conductor portion is the same as the long side of the rectangular cross section of the coil conductor portion 1. less than or equal to the length. The radial width of the third non-magnetic insulator 33 is preferably 0.4 to 1 times the length of the long side (radial length) of the rectangular cross section of the coil conductor portion 1 . In this embodiment, the radial width of the fourth non-magnetic insulator 34 is equal to the length of the long side (radial length) of the rectangular cross section of the coil conductor. The radial width of the nonmagnetic insulator 34 may be less than the length of the long side of the rectangular cross section of the coil conductor portion 1 . The radial width of the fourth nonmagnetic insulator 34 is preferably 0.4 to 1 times the length of the long side of the rectangular cross section of the coil conductor portion 1 . As a result, leakage of magnetic flux from the magnetic body to the coil conductor can be suppressed, eddy current generation inside the coil conductor can be suppressed, copper loss due to the skin effect and proximity effect can be reduced, and the Q value can be increased. can. The magnetic body 2 can be made of a magnetic composite material containing iron-based amorphous magnetic powder such as FeSiCrB, ferrite, electromagnetic steel sheet, sendust, permalloy, Ni-based or Fe-based ferromagnetic material, or the like. The magnetic insulators 33 and 34 can be made of SiO2, alumina, polymeric resin material, or a gas such as air or argon.

In the fifth embodiment, the nonmagnetic insulators are arranged on all long sides of the rectangular cross section of the coil conductor portion 1, but the present invention is not limited to this embodiment. For example, the space between the coil conductors may be filled with the magnetic material 2 without the fourth non-magnetic insulator 34 . Also, the coil conductor portion 1 may have a laminated structure of a conductor and an insulator.

Furthermore, in the fifth embodiment, the long side direction of the rectangular cross section of the coil conductor portion is the radial direction of the coil, but the present invention is not limited to this embodiment. A helical coil having a structure in which a space between the coil conductor portions is filled with a magnetic material and the long side direction of the rectangular cross section of the coil conductor portion is the z-axis direction of the coil may be used. In this case as well, the width of the non-magnetic insulator, which is inserted between the magnetic body and in contact with the coil conductor, in the long side direction of the rectangular cross section of the coil conductor is equal to the length of the rectangular cross section of the coil conductor. It is equal to or less than the length of the side, preferably 0.4 to 1 times the length of the long side of the rectangular cross section of the coil conductor. As a result, leakage of magnetic flux from the magnetic body to the coil conductor can be suppressed, and generation of eddy current inside the coil conductor can be suppressed to increase the Q value.
(Electromagnetic field analysis)

In order to explain the effects of the fifth embodiment, calculation results of electromagnetic field analysis by the finite element method will be explained. The analysis conditions are basically as shown in Table 1, but the current is 4.9A, which is different from the value in Table 1 (0.6A).

In FIG. 15 (as described above, the magnetic body 2 and the non-magnetic insulators 33 and 34 are added to the AA' section of the coil in FIG. 14), the coil conductor has a resistivity of 1.72. It is a 4-turn helical coil made of a copper material of ×10 ⁻⁸ Ωm. The outer diameter (diameter) OD of the coil is 18 mm, the inner diameter (diameter) ID is 8 mm, the radial width of the coil conductor is 5 mm, the film thickness (z-axis direction) of the coil is 0.1 mm, and the distance between the coil conductors. (The thickness of the fourth non-magnetic insulator 34 in the z-axis direction) is 0.105 mm. The coil of the magnetic body 2 has a width of 10 mm in the radial direction (r direction) and a height of 10 mm in the z-axis direction. The film thickness of the third nonmagnetic insulator 33 in the z-axis direction is "dt", and the width of the coil of the third nonmagnetic insulator 33 in the radial direction (r direction) is "dw".

16 to 18 are calculation results of dw dependence when dt changes for the AC resistance R, inductance L and Q value of the inductor according to the fifth embodiment. 16 to 18, when dt is not 0 mm, the inductance L decreases as dw increases, but the AC resistance R also decreases and the Q value increases. When dt is 2 mm or less, the Q value is larger than when dt is 0 mm in the range of dw of 4.8 mm or less.

Also, when dt is 1 mm, the Q value becomes maximum when dw is around 4.4 mm. This corresponds to the case where the magnetic body 2 covers both the top and bottom surfaces of the coil by 0.3 mm.

Examples of inductors according to the present invention will be described below, but the present invention is not limited to the examples described here.
<Example>

19A and 19B are diagrams for explaining the manufacturing process of the inductor of the example.

First, a polyimide-coated copper plate is etched with an etching printer to remove unnecessary polyimide, and two coil-shaped conductors having an inner diameter of 8 mm, an outer diameter of 18 mm, a width of 5 mm, and a thickness of 0.105 mm are produced.

In addition, FeSiCrB amorphous alloy (manufacturer: Epson Atmix Corporation, model number: AW2-08 (no insulation treatment), average particle size: 2.6 μm (spherical)) magnetic powder and epoxy (manufacturer: Taiyo Kinko Co., Ltd., A magnetic composite material is prepared by mixing a binder of Duralco 4460) at a volume filling rate of 57 vol %. This is placed in a predetermined mold and sintered at 120° C. for 4 hours to produce two rectangular parallelepiped composite cores of 20 mm (width)×20 mm (back)×5 mm (height). Next, the surfaces of the two composite cores are milled to form grooves corresponding to the coil-shaped conductors. The groove has a shape in which two stages are depressed at portions corresponding to the outer circumference and the inner circumference of the conductor, respectively, and the conductor can be fitted by using the groove at the first stage as a stopper. The depth of the first stage groove is 0.5 mm, and the depth of the second stage groove is 0.5 mm.

Two composite cores with conductors fitted in the grooves of the first stage are joined together on the conductor side to assemble the inductor. At this time, a 1mm-thick PET sheet having the same shape as the conductor is sandwiched between the two conductors facing each other to form a coil conductor part with a layered structure (sandwich structure) of conductor/PET sheet (insulator)/conductor. do. Two conductors facing each other through the PET sheet are energized in the same direction, and the number of turns of the coil is one. Also, the second stage groove is a gap as a non-magnetic insulator.

FIG. 20 is a photograph of (a) a coil-shaped conductor, (b) a composite core having two grooves, and (c) an inductor assembled by bonding two composite cores.

FIG. 21 is also a schematic diagram of the right side of the cross-section of the example inductor through the center of the coil and parallel to the side of the composite core. The depth (0.5 mm) of the second stage groove corresponds to the thickness of the air gap of the non-magnetic insulator. The radial width of the nonmagnetic insulator air gap is 4.8 mm, which is 0.2 mm narrower than the width (5 mm) of the coil conductor.
<Comparative example>

Next, a comparative example will be described. In a comparative example, an inductor without a gap of a non-magnetic insulator and an insulator between conductors in a coil conductor portion is manufactured. The coil-shaped conductor is prepared by etching a copper plate with polyimide in the same manner as in the example. The conductor has an inner diameter of 8 mm, an outer diameter of 18 mm, a width of 5 mm and a thickness of 0.105 mm. In addition, the composite cores are two rectangular parallelepiped composite cores of 20 mm (width) × 20 mm (depth) × 5 mm (height) that were produced in the same manner as in the example, and the surfaces were milled to correspond to the coil-shaped conductor. grooves. As for the groove, unlike the example, only a single step groove with a depth of 0.5 mm is formed. Furthermore, a conductor with a thickness of 0.105 mm was fitted into the groove in each of the two composite cores, and the same magnetic composite material (mixed material of FeSiCrB amorphous alloy and epoxy, volume filling rate 57 vol%) as that prepared in the example was applied to the composite core. Apply with a squeegee to the surface of the conductor and the step of the conductor. Then, these two composite cores are joined together on the conductor side to assemble the inductor. At this time, currents flow in the same direction through the two conductors facing each other through the magnetic composite material, and the number of turns of the coil is one.

FIG. 22 is a photograph of a composite core coated with a magnetic composite material after the conductor is embedded. Also, FIG. 23 is a schematic diagram of the right side of the cross section of the inductor of the comparative example passing through the center of the coil and parallel to the side surface of the composite core.
(Inductor characteristics)

24 to 26 show the frequency characteristics of AC resistance R, inductance L and Q value measured for the inductors of Example and Comparative Example, respectively. An impedance analyzer (manufactured by Agilent, model number 4294A) was used for the measurement. From FIGS. 24 to 26, it can be seen that in the frequency range of 100 kHz to 10 MHz, the AC resistance R of the example is lower than that of the comparative example, and the Q value of the example is also higher than that of the comparative example. . Table 2 shows a comparison at 5 MHz.

The inductor according to the present invention can be used as an inductor in a power supply such as a DC/DC converter.

1 coil conductor 2 magnetic body 21 first magnetic body 22 second magnetic body 3 nonmagnetic insulator 31 first nonmagnetic insulator 32 second nonmagnetic insulator 33 third nonmagnetic insulator 34 fourth nonmagnetic insulator 4 substrate

Claims (7)

An inductor having a coil wound with a conductor wire having a coil conductor portion with a rectangular cross section and a magnetic body covering the coil,
At least one of the coil conductors is provided with a non-magnetic insulator at a position corresponding to the center of one or both long sides of the rectangular cross section between the magnetic body and the magnetic body, and
The inductor, wherein the magnetic body covers the coil conductor portion in contact with the coil conductor portion at both ends of the coil conductor portion. 2. The inductor according to claim 1, wherein the coil is a planar spiral coil that is spirally wound. 2. The inductor of claim 1, wherein the coil is a spirally wound flat wound coil. The inductor according to claim 1, wherein the coil is a spirally wound helical coil. 2. The inductor according to claim 1, wherein said coil is formed on a flexible substrate. The width of the non-magnetic insulator in the long side direction of the rectangular cross section of the coil conductor portion is 0.4 times or more and less than 1 time the length of the long side of the rectangular cross section of the coil conductor portion. 6. The inductor according to any one of items 1 to 5. 2. The inductor according to claim 1, wherein the coil conductor portion has a laminated structure of a conductor and an insulator.

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