Magnetic core and noise filter

Abstract

Provided is a magnetic core that has high impedance relative permeability in the high frequency range. The magnetic core comprises a plurality of magnetic laminates. The magnetic laminates are formed by layering thin soft-magnetic metal strips and have a height that corresponds to the length in the short direction of the thin soft-magnetic metal strips. The magnetic laminates are stacked in the height direction with a gap therebetween.

Description

Magnetic cores and noise filters

[0001] The present invention relates to a magnetic core and a noise filter.

[0002] Magnetic cores using soft magnetic materials are used as noise filters and magnetic cores for transformers, motors, etc. Examples of soft magnetic materials include sintered ferrite, which is an oxide magnetic material; electromagnetic steel sheets; and wound or laminated ribbons of soft magnetic metals such as amorphous and nanocrystalline materials.

[0003] For example, Patent Document 1 describes that by using a core in which a closed magnetic circuit core is divided parallel to the magnetic path direction and multiple oxide magnetic bodies (sintered bodies) are directly stacked and integrated, the resonant frequency of the geometric resonance effect is increased, thereby improving the characteristics in the high frequency range.

[0004] Furthermore, for example, Patent Document 2 describes that in a core made by winding a thin ribbon of Fe-based nanocrystals, applying a magnetic field in the width direction of the ribbon during heat treatment improves the characteristics in the high frequency range.

[0005] Patent No. 3814776 Patent No. 7028290

[0006] The core described in Patent Document 1 uses a metal material with low resistance, which causes a large amount of eddy current to flow, and there is a risk that high frequency characteristics will deteriorate.

[0007] Furthermore, in the technology described in Patent Document 2, when the core is enlarged, particularly when the dimension of the ribbon in the width direction is increased, the impedance characteristics in the high frequency range of the MHz band may be degraded. Therefore, depending on the core dimensions, there is a risk that the characteristics in the high frequency range may not be improved.

[0008] On the other hand, in a magnetic core made by winding a soft magnetic metal ribbon, the impedance relative permeability in the high frequency range decreases as the dimension in the short-side length direction of the ribbon (height direction of the magnetic core) increases. Therefore, in order to obtain good high frequency characteristics for a magnetic core with a large height dimension, it was necessary to increase the external dimensions of the magnetic core.

[0009] Therefore, an object of the present invention is to provide a magnetic core having a high impedance relative permeability in the high frequency range, and a noise filter having a high noise suppression effect in the high frequency range.

[0010] As a result of intensive research conducted by the inventors to solve the above-mentioned problems, they discovered that by using a plurality of small-height laminated cores (magnetic laminated pieces) as a magnetic core having a constant height dimension formed by laminating soft magnetic metal thin ribbons and arranging the laminated cores at intervals in the height direction, it is possible to achieve a high impedance relative permeability in a frequency band of 1 MHz or more, and further, even if the height dimension of the magnetic core is increased, the above-mentioned high impedance relative permeability can be ensured. The present invention has been made based on the above-mentioned findings. That is, the gist of the present invention is as follows.

[0011] [1] A magnetic core including a plurality of magnetic laminated pieces, wherein the magnetic laminated pieces are formed by laminating soft magnetic metal ribbons, and have heights corresponding to the lengths of the soft magnetic metal ribbons in the short direction, and the magnetic laminated pieces are arranged side by side at intervals in the height direction.

[0012] [2] The magnetic core according to [1], wherein the interval between adjacent magnetic laminated pieces is 0.02 mm or more.

[0013] [3] The magnetic core according to [1] or [2], wherein the height of each of the plurality of magnetic laminated pieces is 0.5 mm or more and 20 mm or less.

[0014] [4] Each of the plurality of magnetic laminated pieces has an annular structure and an average magnetic path length of L ｍ (mm), the height is h (mm), and the radial thickness is t (mm), L ｍ The coefficient Cs calculated by / (h t) is 90.0 mm －１ The magnetic core according to any one of [1] to [3] below.

[0015] [5] The magnetic core according to any one of [1] to [4], wherein the soft magnetic metal ribbon contains an Fe-based nanocrystalline alloy.

[0016] [6] The magnetic core according to any one of [1] to [5], which is used in a frequency band of 1 MHz or more.

[0017] [7] A noise filter comprising the magnetic core according to any one of [1] to [6].

[0018] According to the present invention, it is possible to provide a magnetic core having a high relative permeability to impedance in the high frequency range, and also to provide a noise filter having a high noise suppression effect in the high frequency range.

[0019] 1 is a schematic diagram of a magnetic core according to an embodiment of the present invention and a magnetic laminated piece used in the magnetic core, and a schematic diagram of a surface (a surface formed by longitudinal sides of a soft magnetic metal thin ribbon) of the magnetic laminated piece used in the magnetic core according to an embodiment of the present invention. ａｖｅ 1 is a schematic diagram for explaining the measurement range of the magnetic laminated piece at each frequency with respect to the spacing between the magnetic laminated pieces. ｍｅａｓ / Z ｓｕｍ 10 is a plot of the impedance Z versus frequency characteristics measured in the examples for a magnetic core according to an embodiment of the present invention and a magnetic core according to a comparative example.

[0020] Hereinafter, embodiments of the magnetic core and noise filter of the present invention will be described. However, the description is intended to be an example of the present invention and does not limit the present invention in any way.

[0021] (Magnetic core) A magnetic core according to one embodiment of the present invention (hereinafter sometimes referred to as "the magnetic core of this embodiment") is a magnetic core comprising a plurality of magnetic laminated pieces, each of which is formed by stacking soft magnetic metal ribbons and has a height corresponding to the short-side length (i.e., width) of the soft magnetic metal ribbons, and each magnetic laminated piece is arranged side by side with a gap in the height direction.

[0022] That is, the magnetic core of this embodiment is configured by stacking multiple individually manufactured magnetic lamination pieces (laminated cores) in the height direction, with the magnetic lamination pieces spaced apart. This configuration reduces eddy currents generated inside the core, allowing high magnetic permeability to be maintained even in high-frequency bands of 1 MHz or higher. This configuration also blocks magnetic interactions between the magnetic lamination pieces, further suppressing impedance reduction in the high-frequency range. Therefore, the magnetic core of this embodiment has a high impedance-to-permeability ratio in the high-frequency range, even when the height dimension is increased, without the need for an increase in overall size.

[0023] Furthermore, due to the above-described effects, the magnetic core of this embodiment can be suitably used in the high frequency range, specifically in a frequency band of 1 MHz or higher. In other words, the frequency of the usage environment of the magnetic core of this embodiment is suitably 1 MHz or higher. In particular, when the magnetic core of this embodiment is used in a frequency band of 10 MHz or higher, even greater effects are achieved.

[0024] The magnetic core of this embodiment (or the multiple magnetic laminate pieces that make up the magnetic core) may be housed in a core case. The material of the core case is not particularly limited, and examples include PBT (polybutylene terephthalate), PA (polyamide), PPS (polyphenylene sulfide), ABS (acrylonitrile butadiene styrene), ASA (acrylonitrile styrene acrylic rubber), silicone resin, and silicone elastomer. By housing the magnetic core in the core case, it is possible to protect the magnetic core from external factors such as vibration, impact, and water.

[0025] In the magnetic core of this embodiment, adjacent magnetic lamination pieces may be spaced apart by providing a gap therebetween, or by the interposition of any member. Simply providing a gap can be considered to be an air layer with high electrical resistance, and high magnetic permeability can be maintained in the high frequency band. On the other hand, when providing a gap by the interposition of any member, for example, a resin material may be applied to the opposing surfaces of each magnetic lamination piece (surfaces formed by the longitudinal sides of the soft magnetic metal ribbon), or a plate material may be inserted between each magnetic lamination piece. Furthermore, adjacent magnetic lamination pieces may be integrated by being fixed with a fixture or adhesive, or may be independent without being fixed.

[0026] Furthermore, when spacing is achieved by using an optional intervening member, it is preferable to use a material with high electrical resistance as the member. By spacing each magnetic laminated piece using a material with high electrical resistance, eddy currents generated inside the core are effectively reduced, allowing high magnetic permeability to be maintained even in the high frequency band. Examples of such materials include resin materials such as acrylic resins, epoxy resins, polyethylene resins, polyimide resins, silicone resins, and silicone elastomers. The resin materials may also contain fibers such as glass or cellulose, or particles such as beads. The member may also be insulating paper made of cellulose fibers or the like.

[0027] Alternatively, when resin is impregnated between layers of the soft magnetic metal ribbons of the magnetic laminated pieces (as described below), the resin may be attached to the surface of the magnetic laminated pieces (the surface formed by the longitudinal sides of the soft magnetic metal ribbons) and then solidified and molded in that state to form the above-mentioned gap. In the magnetic core using the magnetic laminated pieces obtained in this case, a gap is formed between adjacent magnetic laminated pieces due to the presence of the resin used for impregnation.

[0028] Alternatively, to form the above-mentioned gaps, the core case may be provided with partitions or protrusions, and the magnetic lamination pieces may be housed in the core case. In this case, the adjacent magnetic lamination pieces in the magnetic core are spaced apart by the partitions or protrusions of the core case.

[0029] In the magnetic core of this embodiment, the spacing (p) between adjacent magnetic laminations may be greater than 0, but is preferably 0.02 mm or greater. A spacing (p) of 0.02 mm or greater provides sufficient insulation between the magnetic laminations, effectively suppressing eddy currents generated within the core. Furthermore, the magnetic interactions between the magnetic laminations are more effectively blocked, suppressing a decrease in impedance relative permeability in the high-frequency range of 1 MHz or greater. From the same perspective, the spacing (p) between adjacent magnetic laminations is more preferably 0.1 mm or greater, and even more preferably 1.0 mm or greater. In particular, a spacing of 0.1 mm or greater can more effectively suppress a decrease in impedance in the high-frequency range of 100 MHz or greater. While there is no particular upper limit to the spacing, an excessively large spacing increases the overall dimensions of the magnetic core, so unnecessary spacing is unnecessary. From this perspective, the spacing is preferably, for example, 20 mm or less.

[0030] The magnetic core of this embodiment includes a plurality of magnetic lamination pieces, i.e., the number of magnetic lamination pieces may be two or more. In particular, the number of magnetic lamination pieces may be, for example, three or more, five or more, or eight or more. On the other hand, the upper limit of the number of magnetic lamination pieces is not particularly limited, but may be, for example, 120 or less, 100 or less, or 80 or less.

[0031] <Soft Magnetic Metal Strip> The soft magnetic metal strip is a component constituting the magnetic laminate piece. In this embodiment, a soft magnetic metal strip having a length (width) in the short side direction corresponding to the height (h) of the magnetic laminate piece to be manufactured can be used.

[0032] Examples of soft magnetic metals include Fe—Ni based alloys (permalloys), Fe—Si based alloys (silicon steel), amorphous alloys such as Co based amorphous alloys and Fe based amorphous alloys, and Fe based nanocrystalline alloys. In particular, the soft magnetic metal ribbon preferably contains an Fe based nanocrystalline alloy. Note that the Fe based nanocrystalline alloy can be obtained, for example, by heat treating an Fe based amorphous alloy to precipitate nanocrystals inside.

[0033] When the soft magnetic metal ribbon contains an amorphous alloy or an Fe-based nanocrystalline alloy, such an alloy may be, for example, an alloy represented by the general formula: (Fe １－ａ M ａ )100-xy-z-b-c-dA ｘ M' ｙ M'' ｚ X ｂ Si ｃ B ｄ (atomic %), wherein M represents at least one element selected from Co and Ni; A represents at least one element selected from Cu and Au; M' represents at least one element selected from Ti, V, Zr, Nb, Mo, Hf, Ta, and W; M'' represents at least one element selected from Cr, Mn, Sn, Zn, Ag, In, platinum group metal elements, Mg, N, and S; X represents at least one element selected from C, Ge, Ga, Al, and P; and a, x, y, z, b, c, and d respectively satisfy 0≦a≦0.1, 0.1≦x≦3, 1≦y≦10, 0≦z≦10, 0≦b≦10, 11≦c≦17, 3≦d≦10, and 65≦100-x-y-z-b-c-d≦85.

[0034] The composition of the Fe-based nanocrystalline alloy is not particularly limited, but is preferably, in atomic percent, Cu: 0.5 to 2.0%, Nb: 1.0 to 5.0%, Si: 11.0 to 15.0%, B: 5.0 to 10.0%, with the balance being substantially Fe, provided that the properties of the present disclosure can be satisfied.

[0035] When the soft magnetic metal ribbon includes an amorphous alloy or an Fe-based nanocrystalline alloy, the thickness of the soft magnetic metal ribbon can be, for example, 10 μm or more and 30 μm or less. If the thickness of the soft magnetic metal ribbon is 10 μm or more, it is possible to suppress a decrease in strength due to the occurrence of voids or discontinuous portions on the ribbon surface, and to suppress the occurrence of deformation or breakage during stacking or winding, thereby suppressing a decrease in magnetic permeability. Furthermore, if the thickness of the soft magnetic metal ribbon is 30 μm or less, it is possible to achieve a sufficient cooling rate to form a uniform amorphous layer and prevent a decrease in magnetic permeability. From the same viewpoint, the thickness of the soft magnetic metal ribbon is more preferably 12 μm or more, even more preferably 14 μm or more, more preferably 25 μm or less, and even more preferably 20 μm or less.

[0036] <Magnetic Laminate Piece> The magnetic laminate piece is formed by laminating soft magnetic metal ribbons. The magnetic laminate piece has a height (h) corresponding to the length of the soft magnetic metal ribbons in the short-side direction. Such a magnetic laminate piece can be produced, for example, by bundling or winding into a roll (cylindrical shape) soft magnetic metal ribbons (metal foils) having a substantially constant length (width) in the short-side direction, cut to a predetermined size and shape.

[0037] The laminated soft magnetic metal ribbons 2 (metal foils) are preferably heat-treated to remove distortion during molding. In other words, the magnetic laminated pieces are preferably obtained by heat-treating laminated soft magnetic metal ribbons. When using soft magnetic metal ribbons containing an amorphous alloy, nanocrystals can be precipitated inside by heat treatment. The heat treatment temperature can be, for example, 350°C to 700°C. The heat treatment is preferably performed in an inert atmosphere such as nitrogen or argon, or in the air.

[0038] Each magnetic lamination piece used in this embodiment may have, for example, an annular structure. Such an annular structure, particularly when the magnetic lamination piece has a height (h) of a certain level or more, can also be referred to as a "tubular structure." By arranging magnetic lamination pieces having an annular structure side by side at intervals in the height direction, the magnetic core can also have an annular structure and a central axis. Furthermore, in such a magnetic core, the height direction of the magnetic lamination pieces and the direction parallel to the central axis of the annular structure are substantially the same. Examples of annular structures include a circular annular structure (having a circular cross section perpendicular to the central axis) or a structure substantially equivalent thereto, a rounded polygonal annular structure (having a rounded polygonal cross section perpendicular to the central axis) or a structure substantially equivalent thereto, and the like. Further examples of the annular structure include a perfect circular annular structure (having a perfect circular cross section perpendicular to the central axis) and an elliptical annular structure (having an elliptical cross section perpendicular to the central axis). Another example is a "racetrack shape," which is similar to an "elliptical annular structure" but differs from an "elliptical annular structure" in that it includes straight line segments.

[0039] The magnetic laminated piece having an annular structure can be produced by winding a soft magnetic metal ribbon. When the magnetic laminated piece having an annular structure is produced by winding a soft magnetic metal ribbon, the soft magnetic metal ribbons are stacked in the radial direction in the magnetic laminated piece.

[0040] Alternatively, each magnetic laminated piece used in this embodiment may have a structure in which a part of the above-mentioned annular structure is cut out, or may have a U-shaped structure.

[0041] Each magnetic lamination piece used in this embodiment preferably has a height (h) of 0.5 mm or more and 20 mm or less. In other words, the short-side length (width) of the soft magnetic metal ribbon used in each magnetic lamination piece is preferably 0.5 mm or more and 20 mm or less. If the height (h) of each magnetic lamination piece is 0.5 mm or more, the soft magnetic metal ribbon and, by extension, each magnetic lamination piece can be more easily manufactured. Furthermore, the proportion of the processed surface in the entire ribbon is reduced, thereby suppressing a decrease in impedance relative permeability due to stress and distortion caused by processing, coarsening of the structure due to processing heat, and the like. Furthermore, if the height (h) of each magnetic lamination piece is 20 mm or less, eddy currents generated inside the core can be more effectively suppressed, thereby suppressing a decrease in impedance relative permeability in the high-frequency range of 1 MHz or more. In particular, if the height (h) of each magnetic lamination piece is 15 mm or less, a decrease in impedance in the high-frequency range of 100 MHz or more can be more effectively suppressed. Furthermore, when resin is impregnated between the layers of the soft magnetic metal ribbons of the magnetic laminated pieces (described later), if the height (h) of each magnetic laminated piece is 20 mm or less, the resin can easily penetrate deep into the core, effectively suppressing distortion of the ribbons inside the core and, ultimately, a decrease in the impedance relative permeability. From the same perspective, it is even more preferable that the height (h) of each magnetic laminated piece is 10 mm or less.

[0042] When each magnetic lamination piece used in this embodiment has a circular structure, each magnetic lamination piece 1 has an average magnetic path length L ｍ (mm), the height is h (mm), and the radial thickness is t (mm), L ｍ The coefficient Cs calculated by / (h t) is 90.0 mm －１ It is preferable that the coefficient Cs is 90.0 mm or less. －１ If the coefficient Cs is 50.0 mm or less, the rigidity of the magnetic core is maintained and deformation due to its own weight or handling is unlikely to occur, so that the decrease in impedance relative permeability can be effectively suppressed. －１ More preferably, it is 10.0 mm or less. －１ On the other hand, the lower limit of the coefficient Cs is set to 1.5 mm in order to reduce the height h and increase the impedance relative permeability in the high frequency range.－１ It is preferable that the thickness is 2.6 mm or more. －１ It is more preferable that the average magnetic path length L ｍ When the outer diameter of the magnetic core is OD, the inner diameter is ID, and the height is h, L ｍ =π(OD+ID) / 2.

[0043] Each magnetic laminate piece used in this embodiment may be an integral piece as shown in Fig. 1. Alternatively, each magnetic laminate piece used in this embodiment may be configured as a split magnetic laminate piece made up of two or more laminate parts (not shown). Specifically, for example, when the magnetic laminate piece has an annular structure, the magnetic laminate piece may be configured as a split core (split magnetic laminate piece) split into at least two or more pieces in the circumferential direction to improve ease of attachment to a cable.

[0044] Furthermore, for example, when the magnetic lamination pieces have an annular structure, the magnetic lamination pieces may be configured to have discontinuous portions that are interrupted in the circumferential direction (not shown). Furthermore, in a magnetic core using a plurality of magnetic lamination pieces having such discontinuous portions, it is preferable that the discontinuous portions of adjacent magnetic lamination pieces do not overlap when viewed in the central axis direction (particularly, that they do not have overlapping portions).

[0045] 2, the magnetic laminate piece used in the magnetic core of this embodiment preferably has resin (impregnated resin in an impregnated state) 3 between the layers of the soft magnetic metal ribbons 2. By impregnating the resin 3 between the layers of the soft magnetic metal ribbons 2 of the magnetic laminate piece 1, the soft magnetic metal ribbons 2 can be fixed and their shape can be maintained.

[0046] The impregnating resin 3 may be, for example, an acrylic resin, an epoxy resin, a polyimide resin, a silicone resin, or a silicone elastomer. The glass transition temperature of the impregnating resin 3 used is preferably 85°C or higher. Recently, products using magnetic cores have been widely used for electric vehicles, and the operating temperature environment is becoming higher due to high-speed operation and high output. Therefore, high heat resistance is also required for the impregnating resin used to solidify and mold the magnetic laminated pieces. In this regard, a glass transition temperature of 85°C or higher, which is one indicator of heat resistance, can improve heat resistance. Furthermore, a glass transition temperature of 85°C or higher can prevent dimensional changes and deterioration of adhesive strength of the impregnating resin 3 due to aging in a high-temperature environment, thereby facilitating fixation of the soft magnetic metal ribbon 2 and maintaining a stable shape. Furthermore, distortion over time within the soft magnetic metal ribbon 2 can be prevented, thereby suppressing a decrease in magnetic permeability. From the same viewpoint, the glass transition temperature of the impregnating resin 3 is more preferably 125° C. or higher, even more preferably 130° C. or higher, and even more preferably 150° C. or higher. In particular, the impregnating resin 3 is preferably an epoxy resin, which can adjust the glass transition temperature by changing the curing agent, has low viscosity before curing, and has high adhesive strength with the soft magnetic metal ribbon 2 after curing.

[0047] When the magnetic laminated piece 1 has resin (impregnated resin) 3 between the layers of the soft magnetic metal ribbons 2, the filling rate of the soft magnetic metal ribbons in the magnetic laminated piece can be adjusted by the binding force when bundling the soft magnetic metal ribbons and the tension when winding them up, and can be adjusted to a range of 65 vol% to 85 vol%, for example. If the filling rate of the soft magnetic metal ribbons in the magnetic laminated piece is 65 vol% or more, the proportion of the magnetic material does not become too small, which effectively suppresses a decrease in magnetic permeability and allows the volume of the magnetic laminated piece 1 to be reduced. On the other hand, if the filling rate of the soft magnetic metal ribbons in the magnetic laminated piece is 85 vol% or less, the interlayer distance d of the soft magnetic metal ribbons 2 does not become too small, which allows the impregnated resin 3 to sufficiently penetrate between the layers of the soft magnetic metal ribbons 2, making it easier to solidify and mold.

[0048] When the magnetic laminated piece 1 has resin (impregnated resin) 3 between the layers of the soft magnetic metal ribbons 2, the total interlayer distance d of the soft magnetic metal ribbons 2 is S, and the average interlayer distance d of the soft magnetic metal ribbons 2 is d ａｖｅ The average interlayer distance between the layers of the soft magnetic metal ribbon 2 is d ａｖｅ The sum of the interlayer distances between layers that are four times or more of ４ When the sum S is ４ The ratio R ４ = S ４ It is preferable that the ratio R is 10.0% or less. When a highly heat-resistant impregnating resin 3 (for example, an impregnating resin 3 having a glass transition temperature of 85° C. or higher) is impregnated into a magnetic laminate (before impregnation), if the glass transition temperature of the resin is high, the viscosity generally tends to be high. In this case, there is a concern that the soft magnetic metal ribbon 2 is particularly likely to be distorted due to the expansion and deformation of the interlayer spaces between the layers, resulting in excessive penetration, and that thermal contraction during curing is large, resulting in a decrease in magnetic permeability. In this regard, in consideration of heat resistance, even when the above-mentioned impregnating resin 3 having a high glass transition temperature is used, the ratio R ４ = S ４ By setting the ratio R / S to 10.0% or less, it is possible to suppress the occurrence of distortion in the soft magnetic metal ribbon 2 and achieve high magnetic permeability of the magnetic laminated piece 1. ４ = S ４ By setting the ratio R / S to 10.0% or less, it is possible to achieve both good heat resistance and good magnetic permeability. ４ = S ４ / S is more preferably 5.0% or less.

[0049] The interlayer distance of the soft magnetic metal ribbons 2 in the magnetic laminated piece 1 can be measured by using an optical microscope to observe the surface of the magnetic laminated piece 1 (the surface formed by the longitudinal sides of the soft magnetic metal ribbons). Specifically, the measurement can be performed according to the procedure described in the Examples.

[0050] The viscosity of the impregnating resin 3 when impregnating the spaces between the layers of the soft magnetic metal ribbon 2 is preferably 2000 mPa·s or less. By impregnating with a relatively low viscosity as described above, it is possible to prevent the occurrence of portions where the impregnating resin 3 does not sufficiently penetrate between the layers of the soft magnetic metal ribbon 2 or portions where the impregnating resin 3 penetrates excessively by expanding or deforming the spaces between the layers of the soft magnetic metal ribbon 2, thereby suppressing a decrease in magnetic permeability due to distortion of the soft magnetic metal ribbon 2. Furthermore, by impregnating with a relatively low viscosity as described above, it is possible to prevent the occurrence of portions where the impregnating resin 3 does not sufficiently penetrate between the layers of the soft magnetic metal ribbon 2 or portions where the impregnating resin 3 penetrates excessively by expanding or deforming the spaces between the layers of the soft magnetic metal ribbon 2, thereby suppressing a decrease in magnetic permeability due to distortion of the soft magnetic metal ribbon 2. ４ = S ４ / S can be made suitable. When using an impregnating resin 3 with high viscosity, it is preferable to adjust the viscosity by adjusting the temperature or adding a diluent such as an organic solvent. From the same viewpoint, it is more preferable that the viscosity of the impregnating resin 3 when impregnating the impregnating resin 3 between the layers of the soft magnetic metal ribbon 2 be 550 mPa s or less.

[0051] The impregnation with the impregnation resin 3 is preferably carried out by heating the uncured impregnation resin 3 to room temperature to 80°C, setting the impregnation pressure to normal pressure to reduced pressure (-0.05 MPaG), and immersing the magnetic laminate piece before impregnation for 10 to 60 minutes. The temperature can be adjusted depending on the viscosity of the impregnation resin 3 used. By setting the impregnation pressure to -0.05 MPaG or more, it is possible to prevent the interlayer spaces of the soft magnetic metal ribbon 2 from expanding and deforming, thereby preventing excessive penetration, and thereby suppressing distortion of the soft magnetic metal ribbon 2 and reducing the magnetic permeability. Furthermore, by setting the impregnation pressure to -0.05 MPaG or more, the ratio R ４ = S ４ / S can be made suitable. The impregnation pressure is more preferably normal pressure. During the immersion, the impregnation liquid can be swung, convected, or vibrated to efficiently remove air bubbles generated between the layers of the soft magnetic metal ribbon 2. Furthermore, if it is difficult to impregnate the soft magnetic metal ribbon 2 with the impregnation resin 3, it is preferable to apply an organic or inorganic adhesive to the surface before laminating the soft magnetic metal ribbon 2 (metal foil).

[0052] After being impregnated with the impregnating resin 3, the magnetic laminated piece 1 can be subjected to a heat treatment to harden the impregnating resin 3. The temperature and time of the heat treatment must be set to appropriate conditions depending on the resin used, but for example, the heat treatment temperature can be 50 to 200°C and the heat treatment time can be 0.5 to 10 hours. Alternatively, the heat treatment can be performed in stages, starting from a low temperature and divided into multiple steps.

[0053] (Noise Filter) A noise filter according to one embodiment of the present invention (hereinafter sometimes referred to as the "noise filter of this embodiment") is characterized by including the magnetic core of the above embodiment. The noise filter of this embodiment uses a magnetic core that has a high impedance relative permeability in the high frequency range, and therefore has a high noise suppression effect in the high frequency range. As a result, it can be attached to power cables or bus bars of electronic devices such as automobiles, power generation / power supply equipment, communication equipment, and office / factory automation equipment, and can be used as a noise filter to suppress noise generated within these electronic devices or noise generated externally and propagating within the cables or bus bars.

[0054] The present invention will be described in more detail below with reference to examples. However, these examples are intended to illustrate the present invention and are not intended to limit the present invention in any way.

[0055] (Example 1: Data on Spacing of Magnetic Laminate Pieces) A ​​magnetic laminate piece was produced by laminating soft magnetic metal ribbons according to the following procedure. First, a molten alloy containing, in atomic percent, 1% Cu, 3% Nb, 13.5% Si, and 9% B, with the remainder being essentially Fe, was quenched by a single-roll method to obtain a ribbon-shaped Fe-based amorphous alloy (Fe-based amorphous alloy ribbon) having a width (length in the short direction) of 15 mm and a thickness of 15 μm. Next, the Fe-based amorphous alloy ribbon was wound (laminated) into a cylindrical shape to obtain a ring-shaped Fe-based amorphous alloy having an outer diameter of 37.0 mm, an inner diameter of 25.0 mm, and a height of 15 mm. The annular Fe-based amorphous alloy was placed in a heat treatment furnace maintained at 600°C under an argon atmosphere and heat-treated for 30 minutes to precipitate nanocrystals inside the Fe-based amorphous alloy, producing a magnetic laminate (before impregnation) in which the soft magnetic metal ribbon contained an Fe-based nanocrystalline alloy. The resulting magnetic laminate (before impregnation) was immersed for 20 minutes under normal pressure in a solution containing a specified ratio of epoxy resin base and curing agent, kept at 50°C, to impregnate the magnetic laminate (before impregnation) with the resin. The resin was then cured by heat treatment at 180°C in air for 8 hours, producing magnetic laminates (magnetic laminate pieces 1A and 1B) with a height of 15 mm and having an annular structure.

[0056] For the prepared magnetic laminated piece, the interlayer distance of the soft magnetic metal ribbon (Fe-based nanocrystalline alloy ribbon) was measured on the surface of the magnetic laminated piece (the surface formed by the longitudinal sides of the soft magnetic metal ribbon). Specifically, the surface of the prepared magnetic laminated piece was finished with abrasive paper of #500 to #2000, and the interlayer distance of the soft magnetic metal ribbon was measured from an image observed at 500x objective magnification using a Hirox digital microscope RH-2000. The measurement of the interlayer distance of the soft magnetic metal ribbon was performed by observing in a straight line in the thickness direction of the soft magnetic metal ribbon from the inner periphery side to the outer periphery side of the magnetic laminated piece, covering 90% of the thickness t of the magnetic laminated piece (45% radially inward and 45% radially outward from the radial center position) (see FIG. 3). The observation locations were three straight lines (three radial lines) equally spaced 120° in the circumferential direction (see FIG. 4), and the average interlayer distance d of the soft magnetic metal ribbon was measured. ａｖｅBased on the obtained interlayer distances of the soft magnetic metal ribbons, the average value d ａｖｅ More than four times (4d ａｖｅ The total interlayer distance S of the soft magnetic metal ribbons ４ The ratio S ４ As a result, the ratio R ４ = S ４ / S was 10.0% or less.

[0057] Furthermore, the impedance Z1 of the magnetic laminate piece 1A was measured at frequencies of 1 MHz, 10 MHz, and 100 MHz. Similarly, the impedance Z2 of the magnetic laminate piece 1B was measured at frequencies of 1 MHz, 10 MHz, and 100 MHz. The impedance measurements were performed using a Keysight 4294A impedance analyzer. Using a lead wire measurement fixture (16047E), a Tanaka Electric Wire H-PCV, Φ0.5 mm single lead wire was passed through the magnetic laminate piece, and the impedances Z1 and Z2 were measured in a one-turn state. Furthermore, the sum of Z1 and Z2, Z, was measured at frequencies of 1 MHz, 10 MHz, and 100 MHz. ｓｕｍ asked for.

[0058] Next, the magnetic laminate pieces 1A and 1B were arranged in contact with each other in the height direction (0 mm spacing) or at predetermined intervals (0.02 mm, 0.04 mm, 0.10 mm, 0.20 mm, 0.50 mm, 1.00 mm, 2.00 mm) (8 positions in total) to prepare a magnetic core. The impedance Z of the magnetic core at frequencies of 1 MHz, 10 MHz, and 100 MHz was measured. ｍｅａｓ was measured in the same manner as above. ｍｅａｓ / Z ｓｕｍ (%) was calculated.

[0059] FIG. 5 shows the relationship between the spacing of the magnetic laminations and Z at each frequency. ｍｅａｓ / Z ｓｕｍ The plot of Z is shown. ｍｅａｓ is the sum of Z of each magnetic laminated piece, Z ｓｕｍIdeally, the impedance should be equal to the impedance of the magnetic laminated pieces. However, when the magnetic laminated pieces were in contact with each other without any spacing, the impedance remained at around 80-85%. This is thought to be due to the increase in eddy currents and magnetic coupling caused by the contact between the two magnetic laminated pieces in the height direction. Because eddy current loss increases with increasing frequency, the impedance was lower at 100 MHz compared to 1 MHz and 10 MHz. In contrast, when the magnetic laminated pieces were spaced apart in the height direction, specifically at a spacing of 0.02 mm, the impedance improved significantly, reaching approximately 99% at 1 MHz and 10 MHz and approximately 93% at 100 MHz. When the spacing between the magnetic laminated pieces was further increased, there was little change at 1 MHz and 10 MHz, but at 100 MHz, the impedance improved to 95% at spacings of 0.10 mm or more.

[0060] (Example 2: Data on the height of the magnetic laminated piece) Except for using an Fe-based amorphous alloy ribbon having a width (length in the short direction) selected from 0.3 to 30.0 mm, a circular Fe-based amorphous alloy having an outer diameter of 37.0 mm, an inner diameter of 25.0 mm, and a height of 0.3 to 30.0 mm was obtained in the same manner as in Example 1. Next, a magnetic laminated piece having a circular structure and a height (h) selected from 0.3 to 30.0 mm was produced in the same manner as in Example 1.

[0061] The magnetic laminated pieces thus produced were subjected to measurement of the interlayer distance of the soft magnetic metal ribbons (Fe-based nanocrystalline alloy ribbons) in accordance with the same procedure as in Example 1. As a result, it was found that all of the magnetic laminated pieces used in the inventive examples had a value within the range of the ratio R ４ = S ４ / S was 10.0% or less.

[0062] The magnetic laminate pieces thus produced were selected and used so that the total height dimension (h x number) was 30 mm, as shown in Table 1, and the magnetic laminate pieces were arranged side by side in the height direction with a 0.02 mm gap (p) between them by sandwiching a 0.02 mm thick polyethylene film between them. In this way, the magnetic cores of each example were produced (the dimensions of the magnetic core, such as the outer diameter and inner diameter, were the same as those of the magnetic laminate pieces).

[0063] For the magnetic cores of each example, the impedance Z was measured at frequencies of 1 MHz, 10 MHz, and 100 MHz in the same manner as in Example 1, and the impedance Z was converted into impedance relative permeability (μrz). The results are shown in Table 1.

[0064] The conversion from impedance Z to impedance relative permeability (μrz) is μrz = Z × L ｍ / (2πμ ０ f × Ae), where μ ０ is the magnetic permeability of a vacuum, L ｍ is the average magnetic path length, f is the measurement frequency, and Ae is the effective cross-sectional area. ｍ Regarding the effective cross-sectional area Ae, when the outer diameter of the magnetic core is OD, the inner diameter is ID, and the height is h, L ｍ = π(OD+ID) / 2, Ae = (OD-ID) × h / 2 × dr, where dr is the packing rate of the magnetic material (soft magnetic metal ribbon), and the density d (g / cm) is calculated from the volume and weight of the magnetic laminated piece. ３ ) to a theoretical density of 7.3 (g / cm ３ ) and in this case it was 0.75 (75 vol%).

[0065]

[0066] Table 1 shows that the magnetic cores of Examples 2-1 to 2-8, in which multiple magnetic laminate pieces were arranged side by side at intervals in the height direction, all had high impedance relative permeability (μrz) at frequencies of 1 MHz, 10 MHz, and 100 MHz. On the other hand, the magnetic core of Comparative Example 2-1, which had a height of 30.0 mm and consisted of a single magnetic laminate piece, had a low impedance relative permeability. This is thought to be due to an increase in eddy currents and distortion of the ribbon during resin impregnation.

[0067] Furthermore, from Examples 2-1 to 2-7 in Table 1, it can be seen that when the height of the magnetic laminated pieces used is in the range of 0.5 to 20 mm, the smaller the height dimension, the higher the impedance relative permeability (μrz) in the high frequency range of 1 MHz or higher. This is because the smaller the height dimension, the smaller the eddy current. On the other hand, Example 2-8, which uses magnetic laminated pieces with a height dimension of 0.3 mm, exhibits characteristics similar to those of Example 2-2 when the height dimension is 15.0 mm, and the effect of reducing the height dimension is small. This is thought to be due to deterioration of the material during manufacturing or deformation of the magnetic laminated pieces.

[0068] (Example 3: Data on various dimensions of toroidal-shaped magnetic laminate pieces) Magnetic laminate pieces having a circular structure (toroidal shape) were produced in the same manner as in Example 2, with various conditions such as dimensions being changed as appropriate.

[0069] The magnetic laminated pieces thus produced were subjected to measurement of the interlayer distance of the soft magnetic metal ribbons (Fe-based nanocrystalline alloy ribbons) in accordance with the same procedure as in Example 1. As a result, it was found that all of the magnetic laminated pieces used in the inventive examples had a value within the range of the ratio R ４ = S ４ / S was 10.0% or less.

[0070] The magnetic laminate pieces thus produced were selected and used so that the total height dimension (h x number) was 30 mm, as shown in Table 2, and the magnetic laminate pieces were arranged side by side in the height direction with a 0.02 mm gap (p) between them by sandwiching a 0.02 mm thick polyethylene film between them. In this way, the magnetic cores of each example were produced (the dimensions of the magnetic core, such as the outer diameter and inner diameter, were the same as those of the magnetic laminate pieces).

[0071] For the magnetic cores of each example produced, the impedance Z was measured at frequencies of 1 MHz, 10 MHz, and 100 MHz in the same manner as in Example 2, and the impedance Z was converted into impedance relative permeability (μrz). The results are shown in Table 2.

[0072]

[0073] From Table 2, it can be seen that the tendency seen in Example 2 (Table 1), that the smaller the height dimension of the magnetic laminated pieces used, the higher the impedance relative permeability (μrz) in the high frequency range of 1 MHz or more, was also seen in Example 3. In other words, it can be seen that this tendency also applies to magnetic cores having various dimensions.

[0074] Example 4: Data on various dimensions of racetrack-shaped magnetic laminated pieces. A toroidal-shaped Fe-based amorphous alloy was obtained in the same manner as in Example 1, except that an Fe-based amorphous alloy ribbon having a predetermined dimension was used. Next, the toroidal-shaped Fe-based amorphous alloy was fixed with a jig to achieve the predetermined dimensions and placed in a heat treatment furnace maintained at 600°C under an argon atmosphere. Heat treatment was performed for 30 minutes to produce a racetrack-shaped magnetic laminated piece (before impregnation). The obtained magnetic laminated piece (before impregnation) was immersed for 20 minutes under normal pressure in a solution containing a mixture of a base resin and a curing agent of an epoxy resin maintained at 50°C in a specified ratio, thereby impregnating the magnetic laminated piece (before impregnation) with the resin. The resin was then cured by heat treatment at 180°C in the atmosphere for 8 hours to produce a racetrack-shaped magnetic laminated piece.

[0075] The magnetic laminated pieces thus produced were subjected to measurement of the interlayer distance of the soft magnetic metal ribbons (Fe-based nanocrystalline alloy ribbons) in accordance with the same procedure as in Example 1. As a result, it was found that all of the magnetic laminated pieces used in the inventive examples had a value within the range of the ratio R ４ = S ４ / S was 10.0% or less.

[0076] The magnetic laminate pieces thus produced were selected and used so that the total height dimension (h x number) was 30 mm, as shown in Table 3, and the magnetic laminate pieces were arranged side by side in the height direction, with a 0.02 mm gap (p) between them by sandwiching a 0.02 mm thick polyethylene film between them. In this way, the magnetic cores of each example were produced (the dimensions of the magnetic core, such as the outer diameter and inner diameter, were the same as those of the magnetic laminate pieces).

[0077] For the magnetic cores of each example produced, the impedance Z was measured at frequencies of 1 MHz, 10 MHz, and 100 MHz in the same manner as in Example 2, and the impedance Z was converted into impedance relative permeability (μrz). The results are shown in Table 3.

[0078]

[0079] From Table 3, even when the magnetic laminated piece has an elliptical ring structure, as in Example 2 (Table 1) and Example 3 (Table 2), it was observed that the smaller the height dimension of the magnetic laminated piece used, the higher the impedance relative permeability (μrz) in the high frequency range of 1 MHz or higher.

[0080] Here, the impedance Z was measured at 10 kHz and 100 kHz for the magnetic core of Inventive Example 4-18 and the magnetic core of Comparative Example 4-3, and the frequency characteristics of the impedance Z are shown in Figure 6. Although the magnetic core of Inventive Example 4-18 and the magnetic core of Comparative Example 4-3 have the same volume, Figure 6 shows that a difference is observed between Inventive Example 4-18 and Comparative Example 4-3 from 100 kHz onwards, and the difference becomes larger as the frequency increases. It can be seen that in the high frequency range of 1 MHz or higher, Inventive Example 4-18 has a significantly higher impedance Z than Comparative Example 4-3. In other words, a magnetic core obtained by using multiple magnetic laminate pieces with small height dimensions and arranging them at intervals in the height direction has a higher impedance Z than a magnetic core of the same volume, and it is thought that the difference becomes particularly large in the high frequency range of 1 MHz or higher.

[0081] As described above, according to the present invention, the performance of magnetic cores used at high frequencies is improved, and it is possible to reduce the volume and weight, which is expected to lead to the miniaturization and weight reduction of components. Note that the dimensions and shapes of the magnetic laminated pieces and magnetic cores shown in the above examples are merely examples, and are not limited to these, as they can be adapted to various dimensions and shapes.

[0082] The magnetic core of the present invention can be attached to power cables or bus bars of electronic devices such as automobiles, power generation / power supply equipment, communication equipment, and office / factory automation equipment, and can be used as a noise filter to suppress noise generated within these electronic devices or noise generated externally and propagating through the cable.

[0083] REFERENCE SIGNS LIST 1 Magnetic laminated piece 2 Soft magnetic metal thin strip 3 Resin (impregnated resin) 10 Magnetic core

Claims

1. A magnetic core comprising a plurality of magnetic laminated pieces, each of which is formed by laminating soft magnetic metal ribbons, has a height corresponding to the length of the soft magnetic metal ribbons in the short direction, and is characterized in that the magnetic laminated pieces are arranged side by side at intervals in the height direction.

2. The magnetic core according to claim 1, wherein the spacing between adjacent magnetic laminated pieces is 0.02 mm or more.

3. A magnetic core according to claim 1 or 2, wherein the height of each of the plurality of magnetic laminated pieces is 0.5 mm or more and 20 mm or less.

4. Each of the plurality of magnetic lamination pieces has a circular structure and an average magnetic path length of L ｍ (mm), the height is h (mm), and the radial thickness is t (mm), L ｍ The coefficient Cs calculated by / (h t) is 90.0 mm －１ 3. The magnetic core according to claim 1, wherein:

5. The magnetic core according to claim 1 or 2, wherein the soft magnetic metal ribbon contains an Fe-based nanocrystalline alloy.

6. The magnetic core according to claim 1 or 2, which is used in a frequency band of 1 MHz or higher.

7. A noise filter comprising the magnetic core according to claim 1 or 2.

Images