JP2018120800A - Wire for coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a short wire for coil having low loss and excellent productivity.SOLUTION: A wire for coil includes a short conductor and a magnetic layer covered on an outer periphery of the conductor, in which the magnetic layer includes a resin and a plurality of magnetic particles dispersed in the resin, the magnetic particles have maximum diameter/equivalent circle diameter of 1.0 or larger and smaller than 1.5. However, the equivalent circle diameter is obtained in such a manner that a contour shape of the magnetic particles in a cross section of the magnetic layer is specified, and a diameter of a circle having the same area as the area surrounded by the contour is obtained, and the maximum diameter is the largest length of the magnetic particles in the contour shape.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a coil wire.

  Patent Document 1 includes a conductor and a magnetic layer formed on the outer periphery of the conductor, and the magnetic layer includes a resin and magnetic particles having a flat cross-sectional shape dispersed in the resin. Is disclosed. Further, it is disclosed that the manufacturing method of the coil wire includes an application step of applying a resin coating in which magnetic particles are dispersed to the outer periphery of the conductor, and a baking step of baking the coating applied to the conductor. . In the above coating process, the thickness of the coating is adjusted by passing the conductor coated with the coating through the coating die, and the coating process and the baking process are repeated until the thickness of the magnetic layer reaches a predetermined thickness. Is going.

JP 2016-46090 A

  Development of a short coil wire is desired. The method for manufacturing a coil wire disclosed in Patent Document 1 is suitable for manufacturing a long coil wire, and there is room for further improvement in manufacturing a short coil wire.

  Then, it is set as one of the objectives to provide the short coil wire which is low loss and excellent in productivity.

The coil wire according to the present disclosure is:
Comprising a short conductor and a magnetic layer coated on the outer periphery of the conductor;
The magnetic layer includes a resin and a plurality of magnetic particles dispersed in the resin,
The magnetic particles have a maximum diameter / equivalent circle diameter of 1.0 or more and less than 1.5.
However, the equivalent circle diameter is the diameter of a circle having the same area as the area surrounded by the contour, specifying the contour shape of the magnetic particles in the cross section of the magnetic layer, and the maximum diameter is It is the maximum length of the magnetic particles in the contour shape.

  The coil wire has a low loss and is short and excellent in productivity.

It is explanatory drawing which shows the coil wire rod of Embodiment 1 typically. It is a schematic perspective view which shows the wire material for coils of Embodiment 2. It is a schematic perspective view which shows an example of the wire material for coils of Embodiment 3. It is a schematic sectional drawing which shows the wire for coils of FIG. It is a schematic sectional drawing which shows another example of the wire material for coils of Embodiment 3. It is a schematic block diagram which shows the measurement circuit used for the measurement of the loss of the wire material for coils in the test example 1. FIG.

[Description of Embodiment of the Present Invention]
In order to manufacture a short coil wire with high productivity, the present inventors examined injection molding of a resin in which magnetic particles are dispersed around a short conductor. In the case of injection molding, a conductor is placed in a mold, a mixture of magnetic particles and resin is injected into the mold, the mixture is formed on the outer periphery of the conductor to a predetermined thickness, and the resin is then added. By solidifying, a coil wire provided with a magnetic layer having a predetermined thickness can be easily obtained.

  However, when a magnetic layer is injection-molded using flat magnetic particles as disclosed in Patent Document 1, the magnetic layer exhibits a function as a magnetic shield that shields an external magnetic field to a conductor. I found it difficult. Therefore, when the magnetic particles in the magnetic layer were examined, there was a variation in the arrangement direction of the major axis and the minor axis of each magnetic particle, and the volume content of the magnetic particles in the magnetic layer was low. all right. That is, when flat magnetic particles are used, in the mixture of magnetic particles and resin at the raw material stage, the magnetic particles exist in various directions in the resin, and the mixture is injected into the mold. Thus, it is considered that it is difficult to control the orientation of the magnetic particles in one direction only by solidifying the resin. The inventors of the present invention have made various studies on a configuration that is excellent in productivity, has a high volume content of magnetic particles in the magnetic layer, and has a high magnetic shielding effect by the magnetic layer. As a result, by using magnetic particles having a nearly spherical shape, it is possible to obtain a coil wire with a high volume content of magnetic particles in the magnetic layer even when the magnetic layer is injection molded. Got. The contents of the embodiments of the present invention will be listed and described below.

(1) A coil wire according to an embodiment of the present invention is:
Comprising a short conductor and a magnetic layer coated on the outer periphery of the conductor;
The magnetic layer includes a resin and a plurality of magnetic particles dispersed in the resin,
The magnetic particles have a maximum diameter / equivalent circle diameter of 1.0 or more and less than 1.5.
However, the equivalent circle diameter is the diameter of a circle having the same area as the area surrounded by the contour, specifying the contour shape of the magnetic particles in the cross section of the magnetic layer, and the maximum diameter is It is the maximum length of the magnetic particles in the contour shape.

  Since the maximum diameter / equivalent circle diameter of the magnetic particles in the magnetic layer is 1.0 or more and less than 1.5, the coil wire has a shape close to a spherical shape. The volume content of the magnetic particles in the magnetic layer can be increased regardless of the arrangement direction. Due to the high volume content of the magnetic particles in the magnetic layer, when an external magnetic field (alternating magnetic field) is applied, the magnetic flux of the magnetic field can be concentrated in the magnetic layer and flow into the conductor. Magnetic flux to be reduced. That is, the magnetic material layer functions as a magnetic shield for the conductor, eddy currents generated in the conductor can be suppressed, and eddy current loss generated in the conductor can be reduced.

  Further, since the magnetic wire has a nearly spherical shape, the coil wire has a high volume content of the magnetic particles in the magnetic layer even when the magnetic layer is injection molded. Is obtained. That is, when magnetic particles close to a sphere are used, in the mixture of the magnetic particles and the resin at the raw material stage, the magnetic particles are likely to be densely and uniformly dispersed in the resin, and the mixture is placed in the mold. This is because by injecting and solidifying the resin, the magnetic particles are densely dispersed in the resin regardless of the arrangement direction. In the case of injection molding, a conductor is placed in a mold ⇒ a mixture of magnetic particles and resin is injected into the mold ⇒ a coil wire having a magnetic layer of a predetermined thickness is obtained by solidifying the resin. Easy to get. Therefore, a short coil wire provided with a magnetic layer composed of magnetic particles close to a spherical shape is excellent in productivity.

  (2) As one form of the said wire material for coils, it is mentioned that the average particle diameter of the said magnetic body particle is 5 micrometers or more and 500 micrometers or less.

  When the average particle size of the magnetic particles is 5 μm or more, it is easy to increase the volume content of the magnetic particles in the magnetic layer. On the other hand, when the average particle diameter of the magnetic particles is 500 μm or less, the magnetic particles are easily dispersed uniformly in the resin.

  (3) As one form of the said wire material for coils, it is mentioned that the volume content rate of the said magnetic body particle in the said magnetic body layer is 60 volume% or more and 90 volume% or less.

  When the volume content of the magnetic particles in the magnetic layer is 60% by volume or more, the saturation magnetic flux density in the magnetic layer can be increased, and the magnetic flux can sufficiently flow through the magnetic layer. Therefore, the magnetic flux linked to the conductor can be reduced more effectively, and the magnetic shield effect can be enhanced. In addition, since the volume content of the magnetic particles in the magnetic layer is 60% by volume or more, it is easy to arrange fine magnetic particles between coarse magnetic particles, and the magnetic layer is projected in the thickness direction. In this case, the region where the magnetic particles do not exist is reduced, and the magnetic flux passing through the magnetic particles can be reduced. On the other hand, when the volume content of the magnetic particles in the magnetic layer is 90% by volume or less, it is easy to realize a state in which the magnetic particles are uniformly dispersed in the resin, and the flow of the resin during molding such as injection molding And filling property can be improved.

  (4) As one form of the coil wire, the magnetic layer has a relative permeability of 10 or more.

  When the relative permeability of the magnetic layer is 10 or more, the magnetic flux can flow more through the magnetic layer, the magnetic flux interlinked with the conductor can be more effectively reduced, and the magnetic shielding effect can be further enhanced. .

  (5) As one form of the said coil wire, the said magnetic body layer is comprised with the partial magnetic body layer formed intermittently with the clearance gap in at least one direction of the longitudinal direction and the circumferential direction of the said conductor. Can be mentioned.

  When the magnetic layer is composed of a partial magnetic layer, the coil wire includes a region (exposed region) where the magnetic layer does not exist in a part of the outer periphery of the conductor. Since the magnetic material constituting the magnetic layer is a metal such as iron, even if an eddy current is generated in the magnetic layer itself by providing an exposed region, the eddy current flows along the longitudinal direction of the conductor. Or an eddy current flowing in the circumferential direction of the conductor can be reduced. Further, by dividing the magnetic layer by the exposed region, even if an eddy current flows in the magnetic layer, the range can be limited, and loss due to the eddy current can be reduced.

  (6) As one form of the coil wire material in which the magnetic layer is composed of a partial magnetic layer, the magnetic layer is a plurality of portions formed intermittently with a gap in the longitudinal direction of the conductor. It is provided with a magnetic layer, and the gap may be more than 0% and not more than 10% with respect to the length of the partial magnetic layer along the longitudinal direction of the conductor.

  Since the magnetic layer is composed of a plurality of partial magnetic layers formed in the longitudinal direction of the conductor, the coil wire has an area (exposed region) in which the magnetic layer does not exist with a predetermined gap in the longitudinal direction of the conductor. ). By providing the exposed region with a predetermined gap in the longitudinal direction of the conductor, it is possible to reduce the flow of eddy current along the longitudinal direction of the conductor. If the gap between adjacent partial magnetic layers (the length along the longitudinal direction of the conductor in the exposed region) is too large, the magnetic shielding effect by the magnetic layer is reduced. Therefore, the gap between the adjacent partial magnetic layers is more than 0% and 10% or less with respect to the length in the longitudinal direction of the conductor in the partial magnetic layer, so that the magnetic flux interlinked with the conductor by the magnetic layer. As a result, the eddy current generated in the conductor can be suppressed and the eddy current generated in the magnetic layer itself can be reduced.

  (7) As one form of the coil wire material in which the magnetic layer is a partial magnetic layer, the conductor is a flat conductor, and is arranged along the longitudinal direction of the flat conductor to constitute the flat conductor. When a set of four opposing surfaces is a first pair of surfaces and a second pair of surfaces, both surfaces constituting the first pair of surfaces are from the ridge line with one surface constituting the second facing surface to the other surface. And at least one surface constituting the second facing surface is an exposed surface from which the rectangular conductor is exposed over the entire surface, and the coated surface It is mentioned that the end surface on the exposed surface side of the magnetic material layer covered with is flush with the exposed surface.

  In the case where the conductor is a flat conductor, the ratio of the conductor cross-sectional area in the cross-section of the coil wire can be increased by forming at least one surface constituting the second facing surface of the conductor as an exposed surface. The magnetic layer may be provided in a region that is susceptible to magnetic flux from an external magnetic field, for example, a region that is substantially parallel to the magnetic flux. That is, the coil wire is arranged so that the first pair of surfaces is substantially parallel to the magnetic flux and the second pair of surfaces is substantially perpendicular to the magnetic flux, thereby allowing the magnetic flux from the external magnetic field to be reduced. It is possible to sufficiently flow through the magnetic layer coated on the first pair of surfaces.

[Details of the embodiment of the present invention]
Hereinafter, a specific example of a coil wire according to an embodiment of the present invention will be described with reference to the drawings. In the figure, the same reference numerals indicate the same names. In FIGS. 1 to 5, the thickness of the magnetic layer is exaggerated for easy understanding. About a conductor and a magnetic body layer, a shape, thickness, width, length, etc. may differ from actuality.

Embodiment 1
A coil wire 1A according to Embodiment 1 will be described with reference to FIG.
The coil wire 1 </ b> A according to Embodiment 1 includes a short conductor 10 and a magnetic layer 20 that covers the outer periphery of the conductor 10. The magnetic layer 20 includes a resin 21 and a plurality of magnetic particles 22 dispersed in the resin 21. The coil wire 1A of the first embodiment is characterized in that the magnetic particles 22 in the magnetic layer 20 satisfy a maximum diameter / equivalent circle diameter of 1.0 or more and less than 1.5, that is, a shape close to a sphere. One. The enlarged view of FIG. 1 shows a state in which magnetic particles of similar sizes are almost aligned for convenience of explanation, but actually, magnetic particles of various sizes are randomly dispersed in the magnetic layer. .

〔conductor〕
The conductor 10 is a portion through which a current mainly flows in the coil wire 1A.

-Composition It is preferable that the conductor 10 contains at least 1 type of metal selected from the metal, especially the copper which is excellent in electroconductivity, copper alloy, aluminum, and aluminum alloy. The conductor 10 including the metals listed above has a high conductivity, and therefore can pass a predetermined current with low loss. From the viewpoint of reducing the loss, copper or a copper alloy is preferable, and from the viewpoint of reducing the weight, aluminum or an aluminum alloy is preferable. The metals listed above are generally non-magnetic materials.

Here, “copper” is pure copper containing 99.9% by mass or more of Cu. Specific examples include tough pitch copper, deoxidized copper (eg, phosphorus deoxidized copper), and oxygen-free copper (OFC).
The “copper alloy” herein is a copper-based alloy containing 50% by mass or more, preferably 90% by mass or more of Cu, and containing an additive element other than Cu. Examples of the additive element of the copper alloy include Sn, Zr, Fe, Zn, Ag, Cr, P, Si, Mn, Ti, Mg, and Ni.
Here, “aluminum” is pure aluminum containing 99 mass% or more of Al.
Here, the “aluminum alloy” is an aluminum-based alloy containing 50% by mass or more, preferably 90% by mass or more of Al and containing an additive element other than Al. Examples of the additive element of the aluminum alloy include Si, Cu, Mg, Zn, Fe, Mn, Ni, Ti, Cr, Ca, Zr, and Li.
In addition, any metal may contain inevitable impurities.

  The content of the additive element may be set as appropriate depending on the type of the additive element as long as desired conductivity is obtained. The total content of additive elements is, for example, 0.1% by mass or more and 30% by mass or less, and further 0.1% by mass or more and 5.0% by mass or less. From the viewpoint of increasing the electrical conductivity, it is preferable that the content of the additive element is small. When the content of the additive element is large, the strength and the like are excellent.

  The conductor 10 preferably has a low oxygen and hydrogen content. When the magnetic layer 20 is provided immediately above the outer periphery of the conductor 10 and the conductor 10 and the magnetic layer 20 are in direct contact, if the conductor 10 contains a large amount of oxygen or hydrogen, the oxygen or hydrogen is magnetic. This is because it may diffuse into the body layer 20 and the ductility and magnetic characteristics of the magnetic layer 20 may be impaired. The oxygen content of the conductor 10 is preferably, for example, 50 ppm or less, and more preferably 10 ppm or less by mass ratio. The hydrogen content of the conductor 10 is preferably, for example, 10 ppm or less, and more preferably 5 ppm or less by mass ratio. For the measurement of the oxygen content, for example, infrared spectroscopy can be used. For measurement of the hydrogen content, for example, an inert gas melting method can be used. In addition, an inert gas melting-infrared absorption method and the like can be mentioned. In consideration of conductivity, low loss, ductility, maintenance of characteristics of the magnetic layer 20, etc., the constituent material of the conductor 10 contains almost no impurities such as oxygen and hydrogen among pure copper, particularly pure copper, and has the highest purity. Oxygen copper is preferred.

-Structure The constituent metal of the conductor 10 is preferably a fine crystal structure because of its excellent mechanical properties. Specifically, the average crystal grain size satisfies 200 μm or less. When the average crystal grain size of the constituent metal is 200 μm or less, the conductor 10 having excellent mechanical properties such as strength (yield stress and 0.2% yield strength) and ductility (breaking elongation) can be obtained. Here, the average crystal grain size is an average crystal grain size measured in accordance with the cutting method described in “Method for testing grain size of drawn copper products” defined in JIS H 0501 (1986). The average crystal grain size is measured by taking a cross section of the coil wire 1A and observing the crystal structure of the cross section of the conductor 10 with a microscope. The average crystal grain size is 100 μm or less, and further 50 μm or less, and the lower limit is not particularly limited. From the viewpoint of production, the average crystal grain size is 1 μm or more.

-Shape The shape of the conductor 10 can be selected as appropriate. FIG. 1 shows a round wire conductor having a circular cross-sectional shape. Round wire conductors are easy to bend and have excellent coil formability. A rectangular conductor having a rectangular cross-sectional shape can easily obtain a coil having a high space factor. In addition, the cross-sectional shape of the conductor 10 includes various shapes such as an elliptical shape, a racetrack shape, a polygonal shape such as a triangular shape and a hexagonal shape. The outer shape of the coil wire 1 </ b> A is similar to the outer shape of the conductor 10, for example, is substantially similar.

-Size The conductor 10 has a short length. Specifically, the length in the longitudinal direction of the conductor 10 is 10 mm to 300 mm, 30 mm to 250 mm, and 100 mm to 200 mm.

The cross-sectional area of the conductor 10 can be appropriately selected according to the current value, for example. For example, in an application in which a large current of 2 A or more flows, the cross-sectional area can be 0.4 mm ² or more, further 0.5 mm ² or more, 0.8 mm ² or more. For low current applications, the cross-sectional area can be less than 0.4 mm ^{2 and even} less than 0.3 mm ² . In the case where the conductor 10 is a round wire conductor as shown in FIG. 1, the diameter may be about 0.5 mm or more and 8 mm or less. In the case of a flat conductor, the length of the short side of the cross section is about 0.2 mm to 5 mm, and the length of the long side is about 0.5 mm to 10 mm.

-Conductivity It is preferable that the conductor 10 has a low loss so that a current can flow with a high conductivity. Specific conductivity includes 70% IACS or more, 80% IACS or more, 90% IACS or more.

[Magnetic layer]
The magnetic layer 20 mainly functions as a magnetic shield that prevents or reduces the magnetic flux from the external magnetic field from passing through the conductor 10. Specifically, the magnetic layer 20 has an effect of reducing the magnetic flux linked to the conductor 10 by flowing a magnetic flux due to the external magnetic field when an external magnetic field is applied to the coil wire 1A. The magnetic layer 20 includes a resin 21 and a plurality of magnetic particles 22 dispersed in the resin 21. The higher the volume content of the magnetic particles 22 in the magnetic layer 20, the higher the magnetic shielding effect. In increasing the volume content, one of the characteristics is that the magnetic particles 22 have a nearly spherical shape.

<resin>
The resin 21 functions as a binder for the plurality of magnetic particles 22 and holds the magnetic particles 22 in a dispersed state. Examples of the resin 21 include polyimide resin, polyamide imide resin, polyester imide resin, polyurethane resin, polyester resin, polyolefin resin, polyamide resin, polyether sulfone resin, polyphenylene sulfide resin, polyether ketone resin, polytetrafluoroethylene resin, poly An insulating resin such as an etherimide resin may be used. Since the resin 21 has electrical insulation, the magnetic layer 20 can be provided with an electrical insulation function.

<Magnetic particles>
Composition The magnetic particles 22 preferably contain at least one metal selected from iron, cobalt, nickel, iron alloys, and iron compounds. The magnetic particles 22 containing the metals listed above have a high saturation magnetic flux density and a high magnetic shielding effect.

Here, “iron”, “cobalt”, and “nickel” contain 99.5 mass% or more of Fe, Co, and Ni, respectively.
The “iron alloy” herein is an iron-based alloy containing 50% by mass or more, preferably 90% by mass or more of Fe and containing an additive element other than Fe. Examples of the additive element of the iron alloy include Si, Ni, Al, Co, and Cr. Specifically, silicon steel (Fe—Si alloy), permalloy (Fe—Ni alloy), permendur (Fe—Co alloy), Sendust (Fe—Si—Al alloy), iron amorphous, etc. Is mentioned. The total content of the additive elements is 1.0% by mass or more and 20% by mass or less, and further 2.0% by mass or more and 18% by mass or less.
Examples of the “iron compound” include iron oxide (iron oxide) such as ferrite (Fe ₂ O ₃ ), FeO, and Fe ₃ O ₄ .
In addition, any metal may contain inevitable pure substances.

-Shape The magnetic particles 22 satisfy a maximum diameter / equivalent circle diameter of 1.0 to less than 1.5. Here, the equivalent circle diameter, as shown in FIG. 1, specifies the contour shape of the magnetic particles 22 in the cross section of the magnetic layer 20, and the diameter of a circle having the same area as the area surrounded by the contour. It is. In addition, the cross section of the magnetic body layer 20 can employ | adopt arbitrary cross sections, and the longitudinal cross section along the longitudinal direction of 1 A of coil wires may be sufficient, and the cross section orthogonal to the longitudinal direction may be sufficient. The maximum diameter is the maximum length of the magnetic particles 22 in the contour shape. The closer the maximum diameter / equivalent circle diameter is to 1.0, the closer the magnetic particles are to a true sphere. In order to determine the area within the contour of the magnetic particles, for example, the magnetic particles are observed with a microscope, and the area within the contour is calculated from the magnetic particles in the observed image by image processing or the like.

  Since the magnetic particles 22 have a nearly spherical shape, the volume content of the magnetic particles 22 in the magnetic layer 20 can be increased. This is because, in the magnetic powder composed of a plurality of magnetic particles 22, if the powder has the same weight, the spherical particles can reduce the bulk of the powder irrespective of the arrangement direction compared to non-spherical particles such as flat shapes. . Since the bulk of the powder is small, the volume content of the magnetic particles 22 in the magnetic layer 20 can be increased without applying high pressure when forming the magnetic layer 20 on the outer periphery of the conductor 10. The maximum diameter / equivalent circle diameter of the magnetic particles 22 is preferably closer to 1.0, more preferably 1.3 or less, 1.2 or less, and particularly preferably 1.1 or less.

  In addition, since the magnetic particles 22 have a nearly spherical shape, even if the magnetic particles 22 are in contact with each other, the magnetic particles 22 are only substantially in point contact and hardly come into surface contact. When the contact area between the magnetic particles 22 dispersed in the resin 21 increases, there is a problem that eddy currents easily flow between the magnetic particles 22. Therefore, it is easy to reduce the flow of eddy current due to the point contact between the magnetic particles 22.

-Size It is preferable that the magnetic particles 22 have an average particle size of 5 μm or more and 500 μm or less. When the average particle diameter of the magnetic particles 22 is 5 μm or more, the volume content of the magnetic particles 22 in the magnetic layer 20 can be easily increased. On the other hand, when the average particle diameter of the magnetic particles 22 is 500 μm or less, the magnetic particles 22 are easily dispersed uniformly in the resin 21. The average particle diameter of the magnetic particles 22 is the diameter of the equivalent circle diameter extracted for 1000 or more magnetic particles 22 present for each observation image, and the average value of 10 or more observation images is the average particle diameter. And The lower limit of the average particle diameter of the magnetic particles 22 is 10 μm or more, 30 μm or more, 60 μm or more, 70 μm or more. The upper limit of the average particle diameter of the magnetic particles 22 is 300 μm or less, 200 μm or less, 150 μm or less, or 100 μm or less.

  The magnetic particles 22 may be a mixture of a plurality of types of particles (coarse particles and fine particles) having different particle sizes. By doing so, fine magnetic particles are arranged between coarse magnetic particles, and when the magnetic layer 20 is projected in the thickness direction, a region where the magnetic particles 22 do not exist is reduced. By doing so, it can reduce that the magnetic flux from an external magnetic field passes between the magnetic body particles 22, and the magnetic flux linked to the conductor 10 can be reduced. The coarse magnetic particles have an average particle size of 100 μm to 300 μm, and more preferably 150 μm to 250 μm. The fine magnetic particles have an average particle size of 30 μm to 60 μm, and further 35 μm to 55 μm.

-Volume content The volume content of the magnetic particles 22 in the magnetic layer 20 is preferably 60% by volume or more and 90% by volume or less. When the volume content of the magnetic particles 22 in the magnetic layer 20 is 60% by volume or more, the saturation magnetic flux density in the magnetic layer 20 can be increased, and the magnetic flux can sufficiently flow through the magnetic layer 20. it can. Therefore, the magnetic flux linked to the conductor 10 can be reduced more effectively. In addition, since the volume content of the magnetic particles 22 in the magnetic layer 20 is 60% by volume or more, the fine magnetic particles 22 can be easily arranged between the coarse magnetic particles 22, and the magnetic layer 20. Is projected in the thickness direction, the area where the magnetic particles 22 do not exist is reduced, and the magnetic flux passing between the magnetic particles 22 can be reduced. On the other hand, since the volume content of the magnetic particles 22 in the magnetic layer 20 is 90% by volume or less, it is easy to realize a state where the magnetic particles 22 are uniformly dispersed in the resin 21, and molding such as injection molding is performed. Sometimes the flowability and filling property of the resin 21 can be improved. Here, the volume content of the magnetic particles in the magnetic layer is determined by measuring the area ratio of the magnetic particles 22 in the magnetic layer 20 from the microscopic observation image of the cross section of the magnetic layer 20. The area ratio of 22 is regarded as the volume content. The volume content of the magnetic particles 22 in the magnetic layer 20 is more preferably 65% by volume to 85% by volume, and particularly preferably 68% by volume to 80% by volume.

<Thickness of magnetic layer>
The average thickness of the magnetic layer 20 is preferably 60 μm or more and 300 μm or less. When the average thickness of the magnetic layer 20 is 60 μm or more, a magnetic path cross-sectional area in the magnetic layer 20 can be sufficiently secured, and a magnetic flux can sufficiently flow through the magnetic layer 20. As the average thickness of the magnetic layer 20 increases, a magnetic flux can flow more through the magnetic layer 20, and it is more preferably 100 μm or more, and particularly preferably 150 μm or more. On the other hand, if the average thickness of the magnetic layer 20 is too thick, there is a risk of loss due to eddy current loss in the magnetic layer 20, and the coil wire 1A is enlarged. Therefore, the average thickness of the magnetic layer 20 is preferably 300 μm or less. Here, the average thickness of the magnetic layer is an average value of the thicknesses measured along the circumferential direction of the magnetic layer 20. Here, the average value of the thicknesses measured at four or more points at equal intervals in the circumferential direction of the magnetic layer 20 is used.

<Arrangement of magnetic layer>
The magnetic layer 20 is provided at least in a region (interlinkage region) that is susceptible to magnetic flux from an external magnetic field. As the interlinkage region, (1) when there is a member that can be arranged close to the coil and can generate a magnetic flux (including leakage magnetic flux), for example, a magnetic core where the coil is placed, a magnet that is placed close to the coil, etc. (2) When a plurality of coil wires 1A are arranged in parallel, for example, when arranged in the axial direction of the spiral coil, or in the radial direction of the spiral coil In the case of being arranged in parallel, an area on the side of the adjacent coil wire material, and the like can be mentioned. In this example, the magnetic layer 20 is provided over the entire outer periphery excluding both end faces of the conductor 10.

<Structure of magnetic layer>
The magnetic layer 20 may have a single layer structure or a multilayer structure of two or more layers. In the case of a multilayer structure, the material of the resin and magnetic particles constituting each layer, the volume content of the magnetic particles in each layer, and the like can be varied.

<Area ratio of magnetic layer>
The area ratio of the magnetic layer 20 in the cross section of the coil wire 1A, specifically, the cross sectional area of the magnetic layer 20 relative to the cross sectional area of the conductor 10 and the magnetic layer 20 in the cross section of the coil wire 1A. The ratio (area ratio) is 3% or more and 40% or less. When the area ratio is 3% or more, a magnetic path area in the magnetic layer 20 can be sufficiently secured, and a magnetic flux can be sufficiently passed through the magnetic layer 20. On the other hand, when the area ratio is 40% or less, eddy current that can be generated in the magnetic layer 20 itself can be reduced. The area ratio is preferably 10% or more and 25% or less. When a plurality of magnetic layers 20 are provided, the area ratio is the sum of the cross-sectional areas of the plurality of magnetic layers 20.

<Physical properties of magnetic layer>
The higher the relative permeability of the magnetic layer 20 is, the higher the magnetic shielding effect is, so that it is preferably 10 or more, and more preferably 15 or more. Moreover, since the magnetic shielding effect is enhanced as the saturation magnetic flux density of the magnetic layer 20 is higher, it is preferably 0.5T or more, and more preferably 1.0T or more. The saturation magnetic flux density and relative permeability of the magnetic layer 20 typically depend on the constituent material of the magnetic layer 20.

[Other configurations]
The coil wire 1A can include an insulating layer (not shown) on the outer periphery of the conductor 10. As an arrangement form of the insulating layer, a form α (disposed on the outer side in the radial direction) of the magnetic layer 20 Hereinafter, this insulating layer may be referred to as an outer insulating layer), form β disposed between the conductor 10 and the magnetic layer 20 (hereinafter, this insulating layer may be referred to as an intervening insulating layer), outer insulation A form γ in which both the layer and the intervening insulating layer are disposed, and a form δ in which an intermediate insulating layer is disposed between the magnetic layers 20 when the plurality of magnetic layers 20 are provided. Typically, in the forms α and γ, the outer insulating layer forms the outermost layer of the coil wire 1A, and in the form β, the magnetic layer 20 forms the outermost layer of the coil wire 1A.

  The coil formed of the coil wire 1 </ b> A having the outer insulating layer can achieve insulation between the coil and its surrounding members and insulation between adjacent coil wires by the outer insulating layer. A coil formed of the coil wire 1 </ b> A including the intervening insulating layer and the intermediate insulating layer can achieve insulation between the conductor 10 and the magnetic layer 20 and insulation between the magnetic layers 20 by these insulating layers. . By this insulation, even if an eddy current is generated in the magnetic layer 20 itself, the eddy current can be prevented from flowing to the conductor 10 or the lower magnetic layer 20.

  The constituent material of the insulating layer includes an insulating resin. Specifically, polyimide resin, polyamide imide resin, polyester imide resin, polyurethane resin, polyester resin, polyolefin resin, polyamide resin, polyether sulfone resin, polyphenylene sulfide resin, polyether ether ketone resin, polytetrafluoroethylene resin, poly Examples include ether imide resins. In addition, these resin may be used independently and may be used in combination of 2 or more type.

  The thickness of the insulating layer can be appropriately selected according to the magnitude of the current flowing through the conductor 10. For example, the thickness of the insulating layer is 5 μm or more and 500 μm or less, and further 5 μm or more and 100 μm or less. Particularly, the lower limit is 30 μm or more and 50 μm or more. The insulating layer can have a single-layer structure or a multilayer structure including two or more layers. In the case of a multilayer structure, the material of each layer can be made different.

  The coil wire 1 </ b> A may include a lubrication layer (not shown) in which an additive such as a lubricity improver is blended in the outermost layer. In addition, the coil wire 1 </ b> A includes an adhesion layer in which an additive such as an adhesion improver is blended between the conductor 10 or the magnetic layer 20 and the insulating layer (intervening insulating layer, outer insulating layer, intermediate insulating layer). (Not shown) may be provided. Or, among the insulating layers, the outer insulating layer that forms the outermost layer of the coil wire 1A is mixed with an additive such as a lubricity improver to improve the lubricity, or the adhesion improver is added to the insulating layer. You may mix | blend an agent and may improve adhesiveness.

  Examples of the lubricity improver include paraffins such as liquid paraffin and solid paraffin, various waxes, and lubricants such as polyethylene resin, fluororesin, and silicone resin. Examples of the constituent material of the lubricating layer include those obtained by binding the lubricant with a binder resin. Examples of the binder resin include the insulating resin described in the section of the insulating layer. The constituent material of the lubricating layer is preferably an amide-imide resin to which lubricity is imparted by adding paraffin or wax. Adhesion improvers include, for example, acetylenes (such as 1-hexyne), alkynols (such as propargyl alcohol and 1-hexyn-3-ol), aldehydes (such as benzaldehyde and cinnamic aldehyde), and amines (laurylamine, N , N′-dimethylcetylamine, trimethylcetylammonium promide, etc.), mercaptans (eg cetyl mercaptan, 2-mercaptoimidazole, 5-amino-1,3,4-thiadiazole-2-thiol), thioureas (thio) Urea, phenylthiourea, etc.), melamine and the like. Among these mercaptans, 2-mercaptoimidazole has a great effect of improving adhesion.

[Production method of coil wire]
The coil wire 1 </ b> A is obtained by injection molding a resin 21 in which a plurality of magnetic particles 22 are dispersed on the outer periphery of the conductor 10. The coil wire manufacturing method includes preparing a conductor, preparing a mixture of resin and magnetic particles, arranging a conductor in a mold, and filling the mold with the mixture. And an injection molding process for solidifying.

-Preparation process In a preparation process, the conductor processed into the predetermined | prescribed shape and dimension and the mixture which disperse | distributed several magnetic body particle | grains (magnetic body powder) in resin are prepared.

  A conductor can be manufactured by plastically processing a conductor material into a short wire having a predetermined shape and size. The material of the conductor can be typically manufactured by a process such as casting → hot working (rolling, forging, extrusion) → cold working (rolling, wire drawing), and appropriate heat treatment.

  The mixture is obtained by charging a resin and magnetic powder into a mixing container and stirring with a stirrer. The magnetic powder (magnetic particles) has a shape close to a spherical shape as described above. The magnetic powder preferably has a density ratio represented by (apparent density / true density) × 100 and more than 45% and 70% or less. Here, the apparent density is a density obtained based on JIS Z 2504 “Metal powder—apparent density test method”, and the true density is a density in which only the volume occupied by the substance itself is a volume for density calculation. It is. If there are no cavities inside individual magnetic particles, the true density can be regarded as the specific gravity of the constituent metal of the magnetic powder. In addition to the magnetic particles having a nearly spherical shape, the mixture satisfies the above range of the density ratio of the magnetic powder, so that the bulk of the powder can be reduced regardless of the arrangement direction of the magnetic powder. The volume content of the magnetic powder can be increased. The resin is preferably prepared by adjusting the viscosity at the time of mixing to 100 mPa · s to 100 Pa · s. By doing so, it can suppress that magnetic body powder precipitates and a magnetic body powder and resin are isolate | separated, and it can be in the state which disperse | distributed several magnetic body particles uniformly in resin. More preferably, the viscosity at the time of mixing of the resin is 1 Pa · s to 50 Pa · s. The viscosity of the resin can be adjusted by changing the temperature of the resin according to the type of resin.

-Placement process In the placement process, conductors are placed in the mold. In that case, a conductor is arrange | positioned so that a predetermined | prescribed clearance gap may be formed between the coating surface where the magnetic body layer is coat | covered among the surfaces of a conductor, and a metal mold | die. A magnetic layer is formed on the outer periphery of the conductor by filling the gap with a mixture during injection molding described later.

-Injection molding process In the injection molding process, the mold is filled with the mixture and solidified. For filling the mixture, the mixture may be simply poured into the mold, the inside of the mold may be pressurized to a low pressure, or the inside of the mold may be decompressed. Finally, by solidifying the resin, a coil wire provided with a magnetic layer having a predetermined thickness can be obtained. When the magnetic layer is injection molded, the magnetic layer has a parting line (not shown) at the position where the mold is divided and a gate mark on which the shape of the injection port for injecting the mixture into the mold is transferred. (Not shown) may be formed.

  In this example, the magnetic layer is provided over the entire outer periphery excluding both end faces of the conductor, but the magnetic layer is intermittently provided with a gap in at least one of the longitudinal direction and the circumferential direction of the conductor. In some cases (see Embodiment 2 and Embodiment 3), the mixture may be filled only in the region where the magnetic layer is provided.

  When the insulating layer is provided, the insulating layer may be covered by so-called two-color molding of the coil wire material obtained by injection molding of the magnetic material layer.

[Use]
The coil wire 1A can be used for an electric device including a coil, for example, a motor, a transformer (transformer), a reactor, and the like.

<< Embodiment 2 >>
With reference to FIG. 2, the coil wire 1B of Embodiment 2 is demonstrated.
The coil wire 1B according to the second embodiment includes a plurality of (three in this example) partial magnetic layers 200 in which the magnetic layer 20 is intermittently formed with gaps 30 in the longitudinal direction of the conductor 10. Is done. That is, in the coil wire 1 </ b> B of the second embodiment, in the outer periphery of the conductor 10, an exposed region (a part of the conductor 10 in the longitudinal direction is covered with the magnetic layer 20 and the other part is not covered with the magnetic layer 20). It is composed of a gap 30). The coil wire 1B of the second embodiment is different from the coil wire 1A of the first embodiment in that the magnetic layer 20 is composed of a plurality of partial magnetic layers 200.

  By providing the gap 30 in the magnetic layer 20, the magnetic material constituting the magnetic layer 20 (partial magnetic layer 200) is a metal such as iron, and an eddy current is generated in the magnetic layer 20 itself. However, it is possible to reduce the eddy current flowing along the longitudinal direction of the conductor 10. In addition, by dividing the magnetic layer 20 by the exposed region, even if an eddy current flows through the magnetic layer 20, the range can be limited, and loss due to the eddy current can be reduced. The effect of reducing the eddy current by providing the gap 30 in the magnetic layer 20 is easily obtained when the average thickness of the magnetic layer 20 is 150 μm or more, and further 200 μm or more.

The gap L ₂ between the partial magnetic layers 200 is preferably such that the interval L ₂ is more than 0% and 10% or less with respect to the length L ₁ of the partial magnetic layer 200. By spacing L ₂ of the gap 30 is 0% of the length L ₁ of the partial magnetic layer 200, an exposed area having no magnetic layer 20 in the longitudinal direction of the conductor 10, partial magnetic layer 200 itself Even when an eddy current is generated in the conductor 10, the eddy current can be reduced from flowing along the longitudinal direction of the conductor 10. On the other hand, the spacing L ₂ of the gap 30 is less than 10% of the length L ₁ of the partial magnetic layer 200, an eddy current generated in the conductor 10 to reduce the magnetic flux interlinked with the conductor 10 of a magnetic material layer 20 Can be suppressed. The interval L _{2 of the} gap 30 is preferably 1% or more and 8% or less and 2% or more and 7% or less with respect to the length L ₁ of the partial magnetic layer 200.

  In this example, the partial magnetic layer 200 is continuously formed in the circumferential direction of the conductor 10, but may be formed intermittently with a gap in the circumferential direction.

  The coil wire 1B is obtained by injection molding a resin 21 (see FIG. 1) in which a plurality of magnetic particles 22 are dispersed on the outer periphery of the conductor 10 in the same manner as the coil wire 1A of the first embodiment. . Therefore, the magnetic layer 20 having a desired shape can be easily formed by making the mold have a desired shape.

<< Embodiment 3 >>
A coil wire 1C according to the third embodiment will be described with reference to FIGS.
In the coil wire 1 </ b> C of the third embodiment, the magnetic layer 20 is intermittently formed with a gap in the circumferential direction of the conductor 10. Specifically, the conductor 10 is a flat conductor, and a set of four opposing faces that are arranged along the longitudinal direction of the flat conductor to constitute the flat conductor is defined as a first pair 10a and a second face 10b, respectively. At least one surface constituting the second facing surface 10b is constituted by the exposed surface 14 from which the conductor 10 is exposed over the entire surface. Both surfaces constituting the first pair of surfaces 10a include a covering surface 12 on which the magnetic layer 20 is coated from a ridge line with one surface constituting the second pair surface 10b to a ridge line with the other surface. 3 and 4 show a form in which one surface constituting the second facing surface 10b is constituted by the exposed surface 14, and FIG. 5 shows that both surfaces constituting the second facing surface 10b are constituted by the exposed surface 14. The form is shown. In the coil wire 1C of the third embodiment, the conductor 10 is a flat conductor, and at least one of the opposing surfaces (second facing surface 10b) constituting the flat conductor (conductor 10) is formed by the exposed surface 14, that is, a magnetic body. The layer 20 is different from the coil wire 1A of the first embodiment in that the layer 20 does not exist over the entire surface of at least one of the opposing surfaces (second facing surface 10b) constituting the flat conductor (conductor 10).

  The magnetic layer 20 may be provided in a region that is susceptible to a magnetic flux from an external magnetic field, for example, a region that is substantially parallel to the magnetic flux (arrows shown in FIGS. 4 and 5). In this case, the magnetic layer 20 is present on at least the first pair of surfaces 10a among the four surfaces that are arranged along the longitudinal direction of the rectangular conductor and constitute the flat conductor, so that the first pair of surfaces 10a substantially with respect to the magnetic flux. By arranging the coil wire 1C so as to be parallel to each other, the magnetic flux from the external magnetic field can be sufficiently passed through the magnetic layer 20, and the magnetic flux linked to the conductor 10 can be reduced. That is, the covering surface 12 of the first pair of surfaces 10a is a parallel surface with respect to the magnetic flux, and the exposed surface 14 of the second facing surface 10b is an intersecting surface with respect to the magnetic flux. Since the magnetic layer 20 is absent on at least one surface constituting the second facing surface 10b, the conductor 10 can be made larger by the absence of the magnetic layer 20, so that the conductor breakage in the cross section of the coil wire 1C can be increased. The area ratio can be increased.

  The end surface on the exposed surface 14 side of the magnetic layer 20 covered with the coated surface 12 is flush with the exposed surface 14 (see FIGS. 4 and 5). By doing so, the coil wire 1C has a smooth outer surface in the circumferential direction, and the contour shape in the cross section is rectangular.

  The coil wire 1C is obtained by injection molding a resin 21 (see FIG. 1) in which a plurality of magnetic particles 22 are dispersed on the outer periphery of the conductor 10 in the same manner as the coil wire 1A of the first embodiment. . Therefore, by setting the mold to a desired shape, at least one surface of the second facing surface 10b of the conductor 10 is defined as an exposed surface 14 so that the contour shape in the cross section of the coil wire 1C is rectangular. In addition, the magnetic layer 20 can be easily formed on the other coated surface 12.

  In this example, the magnetic layer 20 covered with the covering surface 12 is formed continuously in the longitudinal direction of the conductor 10, but may be formed intermittently with a gap in the longitudinal direction. .

  The present invention is not limited to these exemplifications, but is defined by the scope of the claims, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims.

[Test Example 1]
Prepare coil wires with different magnetic layer specifications by injection molding resin with dispersed magnetic particles on the outer periphery of the conductor to form a magnetic layer, and apply a magnetic field from the outside. I investigated the loss.

[Sample preparation: Sample No. 1-1 to 1-3, 1-11]
First, a conductor and a magnetic material constituting the magnetic layer were prepared.
As a conductor, a rectangular conductor made of oxygen-free copper and having a length of 3 mm, a width of 1 mm, and a length of 50 mm was prepared.
As magnetic materials, a magnetic powder made of a Fe-6.5 mass% Si alloy and a polyphenylene sulfide (PPS) resin were prepared. As the magnetic powder, those having a diameter ratio represented by the maximum diameter / equivalent circle diameter of magnetic particles shown in Table 1 were used. Since the magnetic layer of this example is molded at a low pressure as described later, the maximum diameter / equivalent circle diameter of the magnetic particles of the raw material powder and the maximum diameter / equivalent circle diameter of the magnetic particles in the obtained magnetic layer are Substantially the same. A method of obtaining the maximum diameter / equivalent circle diameter will be described later. Table 1 shows the saturation magnetic flux density (Bs) of the magnetic particles in each sample. The saturation magnetic flux density of the magnetic particles was obtained by filling a magnetic powder in a holder and measuring a magnetic flux density-magnetic field curve using a vibrating sample magnetometer (BHV-5, manufactured by Riken Denshi Co., Ltd.). Further, Table 1 shows the density ratio represented by (apparent density / true density) × 100 of the magnetic powder in each sample. Here, the apparent density of the magnetic powder was determined based on JIS Z 2504 “Metal powder—apparent density test method”.
The magnetic material powder and the resin were mixed at a volume ratio of 7: 3 to obtain a magnetic material (mixture).

  Next, the conductor is placed in a mold. At this time, a predetermined gap was provided between the coated surface and the mold so that the entire surface except the end surface of the conductor was coated with the magnetic layer.

  The magnetic material was filled and solidified in the gaps in the mold, a magnetic layer was formed on the outer periphery of the conductor, and a polyamide-imide insulating layer (thickness 30 μm) was further formed on the outer periphery. .

[Measurement of cross-sectional shape of magnetic particles]
The cross section of the magnetic layer in the cross section of the coil wire of each sample was observed with an optical microscope, and from the photographed micrograph, the diameter ratio (maximum diameter / equivalent circle diameter) and average particle diameter of the cross section of the magnetic particles were determined. It was measured. The diameter ratio of the magnetic particles is determined by extracting 1000 or more magnetic particles from the micrograph, specifying the contour shape of each magnetic particle, and determining the diameter of a circle having the same area as the area surrounded by the contour. The equivalent diameter was determined, the maximum length of the magnetic particles in the contour shape was set as the maximum diameter, the maximum diameter / equivalent circle diameter of each magnetic particle was determined, and the average value thereof was determined. Further, the average particle diameter of the magnetic particles (magnetic powder) was determined as an average value in 10 or more photomicrographs, with the equivalent circle diameter as the particle diameter. The results are shown in Table 1.

[Measurement of volume content of magnetic particles]
The cross section of the magnetic layer in the cross section of the coil wire of each sample was observed with an optical microscope, and the volume content of the magnetic particles was measured from the photographed micrograph. For the volume content of the magnetic particles, the total cross-sectional area of the magnetic particles occupying the cross-sectional area of the magnetic layer was measured, the area ratio was determined, and this was regarded as the volume content. The results are shown in Table 1.

[Measurement of magnetic layer thickness]
The cross section of the magnetic layer in the cross section of the coil wire of each sample was observed with an optical microscope, and the thickness of the magnetic layer was measured from the photographed micrograph. The thickness of the magnetic layer was measured at four or more points (at least four points including the central portion of each side of the rectangular conductor) at equal intervals in the circumferential direction over the entire circumference of the magnetic layer, and the average value was obtained. . The results are shown in Table 1.

[Measurement of magnetic properties]
The relative magnetic permeability μ and the saturation magnetic flux density Bs were measured using the coil wire of each sample as a sample and using a BH curve tracer “BHS-40S10K” manufactured by Riken Denshi Co., Ltd. The results are shown in Table 1.

(Measurement of loss)
The measurement circuit shown in FIG. 6 was configured, and the loss in the coil wire of each sample was examined using this measurement circuit. A measurement circuit 100 shown in FIG. 6 includes a C-shaped magnetic core 110 having a gap 111 formed therein, a primary coil 121 and a secondary coil 122 wound around the magnetic core 110, and a signal generator 131. H analyzer 130 is provided. The coil wire of each sample is inserted as a measurement sample S into the gap 111 of the magnetic core 110. An excitation signal is generated from the signal generator 131 of the BH analyzer 130, an excitation current i ₁ is passed through the primary coil 121 via the amplifier 132, and an alternating magnetic field is generated in the gap 111. From the AC resistance component obtained by measuring the exciting current i ₁ flowing through the resistor 133 and the induced voltage V ₂ generated at both ends of the secondary coil 122 when the measurement frequency and magnetic flux density of the AC magnetic field are changed, the measurement system Find the loss. Here, a comparative sample consisting only of a copper wire having substantially the same material, shape and size as the conductor wire in the coil wire of each sample and having no magnetic layer is prepared. Also measure the loss. The loss of the coil wire of each sample was evaluated as a relative value (%) with respect to 100 as the loss in the comparative sample having no magnetic layer, and the results are shown in Table 1.

  As shown in Table 1, the sample No. 1 in which the diameter ratio of the magnetic particles is less than 1.5. In 1-1, 1-2, and 1-3, it was found that the volume content of the magnetic particles in the magnetic layer was 60% by volume or more, and the loss ratio was reduced to 80% or less. This is because the magnetic particles have a shape close to a spherical shape, and therefore exist in the resin regardless of the arrangement direction of the magnetic particles, and when the magnetic layer is projected in the thickness direction, the magnetic particles do not exist. This is thought to be due to the reduction of In particular, in the raw material stage, Sample No. using a magnetic powder having a high density ratio of 60 was used. In 1-2 and 1-3, it was found that the volume content of the magnetic particles in the magnetic layer was 70% by volume or more, and the loss ratio could be further reduced to 67% or less. Furthermore, it was found that the loss ratio can be reduced to 50% as the thickness of the magnetic layer is increased. On the other hand, Sample No. with a magnetic particle diameter ratio of 1.5. 1-11 shows that the volume content of the magnetic particles in the magnetic layer is as low as 31% by volume, and the loss ratio can be reduced only by 95%, which makes it difficult to exhibit the function as a magnetic shield by the magnetic layer. It was. This is because the magnetic particles are non-circular, and when the magnetic layer is projected in the thickness direction due to variations in the arrangement direction of the magnetic particles, a region where no magnetic particles exist is formed. it is conceivable that.

[Test Example 2]
Sample No. 1 in Test Example 1 In 1-2 and 1-3, the wire rod for a coil constituted by a plurality of (three in this example) partial magnetic layers each of which is formed intermittently with a gap in the longitudinal direction of the conductor. In addition, samples with different gap ratios between the partial magnetic layers were prepared, and the loss when a magnetic field was applied from the outside was examined. Sample No. 2-1, sample No. 1-2, the same as Sample No. Sample No. 2-4 Same as 1-3. The clearance rate, is that the ratio of the distance L ₂ of the gap to the length L ₁ of the partial magnetic layer (see Figure 2). Table 2 shows the thickness, gap ratio, and loss ratio of the magnetic layer of each sample. The loss ratio was measured in the same manner as in the first embodiment.

  As shown in Table 2, it was found that even when the magnetic layer was composed of a plurality of partial magnetic layers, the loss ratio could be reduced to 70% or less if the gap ratio was 10% or less. In particular, it was found that when the thickness of the magnetic layer is 300 μm, the loss ratio can be further reduced by providing a gap with a gap ratio of 10% or less as compared with the case where no gap is provided. This is because if the magnetic layer is thick, the eddy current flowing in the partial magnetic layer itself increases, so by providing a gap between the magnetic layers, the eddy current can be effectively reduced. Conceivable. On the other hand, when the thickness of the magnetic layer is 100 μm, the eddy current flowing through the partial magnetic layer itself is smaller than that when the thickness of the magnetic layer is 300 μm. The effect is considered small. When the thickness of the magnetic layer is 100 μm, the loss ratio increases as the gap ratio between the partial magnetic layers increases, which is considered to be due to a decrease in the magnetic shielding effect by the magnetic layer. As described above, depending on the thickness of the magnetic material layer, by providing a gap between the magnetic material layers, an exposed region in which the magnetic material layer does not exist is formed in the longitudinal direction of the conductor, so eddy currents are generated in the partial magnetic material layer itself. Even if it occurs, it is considered that the eddy current can be prevented from flowing along the longitudinal direction of the conductor.

[Test Example 3]
Sample No. 1 in Test Example 1 In 1-2, the coil wire material which is arranged along the longitudinal direction of the rectangular conductor and is formed of an exposed surface which does not cover the magnetic layer over the entire surface of the four surfaces constituting the rectangular conductor. The loss when applying a magnetic field was investigated. The magnetic layer coated on the coated surface is formed continuously in the longitudinal direction of the conductor. At this time, when the set of four opposing surfaces constituting the rectangular conductor is a first pair of surfaces and a second pair of surfaces, respectively, the first pair of surfaces is substantially parallel to the magnetic flux, and the second surface is against the magnetic flux. The rectangular conductors were arranged so as to substantially intersect. In other words, the first pair of surfaces are parallel surfaces with respect to the magnetic flux (upper and lower surfaces in FIGS. 4 and 5), and the second pair of surfaces are cross surfaces with respect to the magnetic flux (the left and right surfaces in FIGS. 4 and 5). Table 3 shows the arrangement of the magnetic layers and the loss ratio. The loss ratio was measured in the same manner as in the first embodiment.

  As shown in Table 3, it is found that the loss ratio can be reduced to 54% or less when both the first pair of surfaces are coated surfaces (the magnetic layer is coated) and at least one of the second surfaces is an exposed surface. It was. On the other hand, it was found that when at least one of the first pair of surfaces is an exposed surface, the loss ratio can be reduced only to 85% even if both of the second facing surfaces are coated surfaces. In particular, it has been found that when both of the first pair of surfaces are exposed surfaces, the loss ratio cannot be reduced at all. From this, it is understood that, in a flat conductor, it is possible to expose the entire surface intersecting with the magnetic flux by providing the magnetic layer on the surface substantially parallel to the magnetic flux. It was. By providing the conductor with an exposed surface, the ratio of the conductor cross-sectional area in the cross section of the coil wire can be increased.

1A, 1B, 1C Coil wire 10 Conductor 10a First pair 10b Second face 12 Covered surface 14 Exposed surface 20 Magnetic layer 200 Partial magnetic layer 21 Resin 22 Magnetic particles 30 Gap 100 Measurement circuit S Measurement sample (for coil wire)
110 Magnetic Core 111 Gap 121 Primary Coil 122 Secondary Coil 130 BH Analyzer 131 Signal Generator 132 Amplifier 133 Resistance

Claims (7)

Comprising a short conductor and a magnetic layer coated on the outer periphery of the conductor;
The magnetic layer includes a resin and a plurality of magnetic particles dispersed in the resin,
The magnetic particles have a maximum diameter / equivalent circle diameter of 1.0 to less than 1.5.
However, the equivalent circle diameter is the diameter of a circle having the same area as the area surrounded by the contour, specifying the contour shape of the magnetic particles in the cross section of the magnetic layer, and the maximum diameter is It is the maximum length of the magnetic particles in the contour shape.   The coil wire according to claim 1, wherein an average particle diameter of the magnetic particles is 5 μm or more and 500 μm or less.   3. The coil wire according to claim 1, wherein a volume content of the magnetic particles in the magnetic layer is 60 volume% or more and 90 volume% or less.   The wire material for a coil according to any one of claims 1 to 3, wherein the magnetic layer has a relative permeability of 10 or more.   5. The magnetic material layer according to claim 1, wherein the magnetic material layer includes a partial magnetic material layer that is intermittently formed with a gap in at least one of a longitudinal direction and a circumferential direction of the conductor. The coil wire described in 1. The magnetic layer includes a plurality of partial magnetic layers formed intermittently with gaps in the longitudinal direction of the conductor,
The wire for a coil according to claim 5, wherein the gap is more than 0% and not more than 10% with respect to the length of the partial magnetic layer in the longitudinal direction of the conductor. The conductor is a flat conductor,
When a set of four opposing surfaces arranged along the longitudinal direction of the flat conductor to constitute the flat conductor is a first pair and a second, respectively,
Both surfaces constituting the first pair of surfaces include a covering surface on which the magnetic layer is coated from a ridge line with one surface constituting the second facing surface to a ridge line with the other surface,
At least one surface constituting the second facing surface is composed of an exposed surface where the flat conductor is exposed over the entire surface,
7. The coil wire according to claim 5, wherein an end surface of the magnetic layer covered by the covering surface on the exposed surface side is flush with the exposed surface.

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