inductor

Abstract

An inductor (1) has a wire (2) having a conductor (4) and an insulating film (5) disposed on the entire circumference of the conductor (4), and a magnetic layer (3) in which the wire (2) is embedded. The magnetic layer 3 contains magnetic particles. The magnetic layer (3) has a first layer (10) in contact with the circumference of the wire (2), a second layer (20) in contact with the surface of the first layer, and an n-th layer (n is a positive number of 3 or more) in contact with the surface of the (n-1)-th layer. In two adjacent layers in the magnetic layer (3), the relative permeability of the layer closer to the wire (2) is lower than the relative permeability of the layer farther from the wire (2).

Description

Technical Field

[0001] This invention relates to an inductor. Background Technology

[0002] Inductors are known to be passive components mounted in electronic devices and used as voltage conversion components.

[0003] For example, an inductor has been proposed having a rectangular substrate body made of a magnetic material and an internal conductor made of copper embedded inside the substrate body (see, for example, Patent Document 1 below).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 10-144526 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] However, the inductor in Patent Document 1 has a drawback: insufficient DC superposition characteristics.

[0009] This invention provides an inductor with excellent DC superposition characteristics.

[0010] Solution for solving the problem

[0011] The present invention (1) includes an inductor having: wiring having conductors and an insulating film disposed on the entire circumference of the conductors; and a magnetic layer in which the wiring is embedded, the magnetic layer comprising magnetic particles, the magnetic layer having a first layer in contact with the circumference of the wiring, a second layer in contact with the surface of the first layer, ... an nth layer in contact with the surface of the (n-1)th layer (n is a positive number of 3 or more), wherein in two adjacent layers of the magnetic layer, the relative permeability of the layer closer to the wiring is lower than the relative permeability of the layer farther from the wiring.

[0012] The present invention (2) includes the inductor described in (1), wherein the wiring has a generally circular shape when viewed in cross-section.

[0013] The present invention (3) includes the inductor described in (2), wherein any one of the second to nth layers has a generally arc-shaped cross-section that shares a common center with the wiring.

[0014] The present invention (4) includes an inductor as described in any one of (1) to (3), wherein any one of the first layer to the nth layer has an extension extending from the wiring in a direction orthogonal to the direction of the extension of the wiring and the thickness direction of the magnetic layer.

[0015] The present invention (5) comprises an inductor as described in any one of (1) to (4), wherein the magnetic particles contained in the first layer have a generally spherical shape and the magnetic particles contained in the second to nth layers have a generally flat shape.

[0016] The present invention (6) includes an inductor as described in any one of (1) to (5), wherein the magnetic particles contained in at least the second layer are oriented along the outer peripheral surface of the wiring.

[0017] The effects of the invention

[0018] The inductor of this invention has excellent DC superposition characteristics. Attached Figure Description

[0019] Figure 1 A front sectional view showing one embodiment of the inductor of the present invention.

[0020] Figure 2 Indicates to Figure 1 A front sectional view illustrating the manufacturing method of the inductor shown.

[0021] Figure 3 This is a front sectional view of the inductor corresponding to the first embodiment.

[0022] Figure 4 Indicates to Figure 3 A front sectional view illustrating the manufacturing method of the inductor shown.

[0023] Figure 5 This is a front sectional view of the inductor corresponding to the second embodiment.

[0024] Figure 6 Indicates to Figure 5 A front sectional view illustrating the manufacturing method of the inductor shown.

[0025] Figure 7 express Figure 1 A front sectional view of a modified example of the inductor shown (a modified example with an extension in the second layer).

[0026] Figure 8 express Figure 1 A front sectional view of a modified example of the inductor shown (a modified example in which layers 1 through 4 are each composed of 1 layer). Detailed Implementation

[0027] <One Implementation Method>

[0028] Reference Figure 1 This describes one embodiment of the inductor of the present invention.

[0029] <Basic Forms of Inductors>

[0030] like Figure 1 As shown, the inductor 1 has a shape extending along the surface direction. Specifically, the inductor 1 has one side and another side opposite each other in the thickness direction, both of which have a flat shape along a first direction included in the surface direction and orthogonal to the direction in which the current is transmitted by the wiring 2 (described later) (corresponding to the paper depth direction) and the thickness direction.

[0031] Inductor 1 has wiring 2 and magnetic layer 3.

[0032] <Wiring>

[0033] Wiring 2 has a generally circular shape when viewed in cross-section. Specifically, wiring 2 has a generally circular shape when cut with a cross-section (first direction cross-section) orthogonal to the direction of current transmission, i.e., the second direction (transmission direction) (depth direction of the paper).

[0034] Wiring 2 has a conductor 4 and an insulating film 5 covering the conductor 4.

[0035] Conductor 4 is a conductor wire that extends relatively long in the second direction. In addition, conductor 4 has a shape that shares a central axis with wiring 2 and is approximately circular in cross-section.

[0036] Examples of materials for the conductor 4 include metallic conductors such as copper, silver, gold, aluminum, nickel, and their alloys, with copper being a preferred choice. The conductor 4 can be a single-layer structure or a multi-layer structure formed by plating (e.g., nickel) on the surface of the core conductor (e.g., copper).

[0037] The radius of the conductor 4 is, for example, 25 μm or more, preferably 50 μm or more, and also, for example, 2000 μm or less, preferably 200 μm or less.

[0038] The insulating film 5 protects the conductor 4 from chemicals and water, and also prevents short circuits between the conductor 4 and the magnetic layer 3. The insulating film 5 covers the entire outer circumferential surface of the conductor 4.

[0039] The insulating film 5 has a roughly circular shape in cross-section, sharing a central axis (center) with the wiring 2.

[0040] Examples of insulating materials for the insulating film 5 include polyvinyl alcohol formaldehyde, polyester, polyesterimide, polyamide (including nylon), polyimide, polyamideimide, polyurethane, and other insulating resins. These materials can be used individually or in combination of two or more.

[0041] The insulating film 5 can be composed of a single layer or multiple layers.

[0042] Regarding the thickness of the insulating film 5, at any position in the circumferential direction, the thickness of the insulating film 5 is approximately uniform in the radial direction of the wiring 2, for example, 1 μm or more, preferably 3 μm or more, and also, for example, 100 μm or less, preferably 50 μm or less.

[0043] The ratio of the radius of the conductor 4 to the thickness of the insulating film 5 is, for example, 1 or more, preferably 5 or more, for example, 500 or less, and preferably 100 or less.

[0044] The radius R of the wiring 2 (which is the sum of the radius of the conductor 4 and the thickness of the insulating film 5) is, for example, 25 μm or more, preferably 50 μm or more, and also, for example, 2000 μm or less, preferably 200 μm or less.

[0045] <Summary of the magnetic layer (layer structure, shape, etc.)>

[0046] The magnetic layer 3 increases the inductance of the inductor 1 and also improves its DC superposition characteristics. The magnetic layer 3 covers the entire outer peripheral surface (circumferential surface) of the wiring 2. Thus, the wiring 2 is embedded within the magnetic layer 3. The magnetic layer 3 forms the shape of the inductor 1.

[0047] Specifically, the magnetic layer 3 has a rectangular shape extending along the surface direction (the first direction and the second direction).

[0048] More specifically, the magnetic layer 3 has one side and another side opposite to each other in the thickness direction, and one side and the other side of the magnetic layer 3 respectively form one side and the other side of the inductor 1.

[0049] The magnetic layer 3 has a first layer 10 for embedding wiring 2, a second layer 20 in contact with the surface of the first layer 10, a third layer 30 in contact with the surface of the second layer 20, and a fourth layer 40 in contact with the surface of the third layer 30.

[0050] Furthermore, at the position overlapping with wiring 2 (overlapping position), layers 10, 20, 30, and 40 are arranged on both sides of wiring 2 in the thickness direction. At the position offset from wiring 2 in the projection plane along the first direction in the thickness direction, layers 10, 20, 30, and 40 are arranged on both sides of the thickness direction from the middle part (central part) of the magnetic layer 3.

[0051] The first layer 10 has a shape extending along the surface direction, having one side 11 and another side 12 facing each other in the thickness direction. Furthermore, the first layer 10 covers the entire outer peripheral surface (circumferential surface) of the insulating film 5. Thus, the insulating film 5 is embedded in the first layer 10. Therefore, the first layer 10 also has an inner peripheral surface 13 that contacts the outer peripheral surface of the insulating film 5.

[0052] The first layer 10 includes a generally arc-shaped section that shares a center with the wiring 2. Specifically, in section, the first layer 10 integrally has a first arc portion 15 on one side, a first arc portion 16 on the other side, and an extension 17.

[0053] The first arcuate portion 15 on one side is positioned on the side closer to the center of the wiring 2 in the thickness direction. In cross-section, the first arcuate portion 15 on one side is radially opposite to a region 18 on the circumferential surface of the wiring 2 on the side closer to the center of the wiring 2 in the thickness direction. One surface 11 of the first arcuate portion 15 on one side forms an arcuate surface sharing a center with the wiring 2. The central angle of the first arcuate portion 15 on one side is, for example, less than 180 degrees, preferably less than 135 degrees, and more than 30 degrees, preferably more than 60 degrees.

[0054] In cross-section, the first arcuate portion 16 on the other side is radially opposite to the other side region 19 on the circumferential surface of the wiring 2, which is on the side closer to the center of the wiring 2 in the thickness direction. The other side 12 of the first arcuate portion 16 on the other side forms an arcuate surface that shares a center with the wiring 2. The central angle of the first arcuate portion 16 on the other side is, for example, less than 180 degrees, preferably less than 135 degrees, and more than 30 degrees, preferably more than 60 degrees.

[0055] The total central angle of the first arc portion 15 on one side and the first arc portion 16 on the other side is, for example, less than 360 degrees.

[0056] Furthermore, the first arc portion 16 on the other side and the first arc portion 15 on one side are symmetrical with respect to the imaginary surface passing through the center of the wiring 2 along the surface direction.

[0057] The extension 17 has a shape that extends outward from the wiring 2 in a first direction. The first layer 10 has two extensions 17. The two extensions 17 are respectively disposed on both outer sides of the wiring 2 in the first direction. The two extensions 17 extend outward from the circumferential surface of the wiring 2 between the first arc portion 15 on one side and the first arc portion 16 on the other side in the first direction, respectively, reaching both end faces of the inductor 1 in the first direction. One side 11 and the other side 12 of the extension 17 are parallel. The extension 17 has the shape of two flat strips that extend in a second direction on both outer sides of the wiring 2 in the first direction when viewed from above.

[0058] The thickness of the first arc portion 15 on one side and the first arc portion 16 on the other side is, for example, 1 μm or more, preferably 5 μm or more, and also, for example, 1000 μm or less, preferably 800 μm or less. The thickness of the extension portion 17 is, for example, 2 μm or more, preferably 10 μm or more, and also, for example, 2000 μm or less, preferably 1600 μm or less.

[0059] The thickness of the first layer 10 is equivalent to the total thickness of the first arc portion 15 on one side and the first arc portion 16 on the other side, and also equivalent to the thickness of the extension 17. Specifically, the thickness of the first layer 10 is, for example, 2 μm or more, preferably 10 μm or more, and for example, 2000 μm or less, preferably 1600 μm or less, more preferably 1000 μm or less, and even more preferably 500 μm or less.

[0060] The ratio of the thickness of the first layer 10 to the thickness of the magnetic layer 3 (described later) is, for example, 0.01 or more, preferably 0.05 or more, more preferably 0.1 or more, even more preferably 0.2 or more, especially preferably 0.3 or more, and for example, 0.5 or less, preferably 0.4 or less.

[0061] If the ratio of the thickness of the first layer 10 to the thickness of the magnetic layer 3 is above the lower limit mentioned above, then sufficient distance between the second layer 20 and the wiring 2 can be ensured, and magnetic saturation of the second layer 20, the third layer 30 and the fourth layer 40 can be suppressed. That is, excellent DC superposition characteristics can be maintained, and layers with higher relative permeability can be arranged after the second layer 20.

[0062] The second layer 20 independently has a second layer 21 on one side and a second layer 22 on the other side.

[0063] One side of the second layer 21 contacts one side 11 of the first layer 10. The second layer 21 has a shape that follows the shape of one side 11 of the first layer 10, including a first arcuate portion 15 and two extensions 17. The second layer 21 has another side 24 that contacts one side 11 of the first layer 10, and another side 23 that is spaced apart from the other side 24 in the thickness direction. The second layer 21 also has a second arcuate portion 27 that shares a center with the wiring 2 and is generally arcuate in cross-section.

[0064] The second layer 22 on the other side is disposed opposite to the first layer 10 on the other side in the thickness direction of the second layer 21 on the other side. The second layer 22 on the other side is in contact with the other side 12 of the first layer 10. The second layer 22 on the other side has the shape of the other side 12 following the first arcuate portion 16 and the two extensions 17 of the first layer 10. The second layer 22 on the other side has a side 25 that is in contact with the other side 12 of the first layer 10 and another side 26 that is disposed at a distance from the side 25 on the other side in the thickness direction of the side 25. The second layer 22 on the other side has a second arcuate portion 28 on the other side that shares a center with the wiring 2 and is generally arcuate in cross-section.

[0065] The second layer 22 on the other side and the second layer 21 on one side are symmetrical with respect to the imaginary surface passing through the center of the wiring 2 along the surface direction.

[0066] The thickness of the second layer 20 is the total thickness of the second layer 21 on one side and the second layer 22 on the other side, for example, 1 μm or more, preferably 5 μm or more, and for example, 1000 μm or less, preferably 800 μm or less.

[0067] The ratio of the thickness of the second layer 20 to the thickness of the magnetic layer 3 (described later) is, for example, 0.01 or more, preferably 0.05 or more, and also, for example, 0.5 or less, preferably 0.4 or less.

[0068] The ratio of the thickness of the second layer 20 to the thickness of the first layer 10 is, for example, 0.1 or more, preferably 0.2 or more, and also, for example, 100 or less, preferably 10 or less.

[0069] The third layer 30 independently has a third layer 31 on one side and a third layer 32 on the other side.

[0070] The third layer 31 on one side is in contact with the second layer 21 on the other side. Furthermore, the third layer 31 on one side has approximately the same thickness throughout the first direction. The third layer 31 on one side has another side 34 that is in contact with one side 23 of the second layer 21 on one side, and another side 33 that is spaced apart from the other side 34 on the thickness direction side of the other side 34. The third layer 31 on one side has a shape that extends along the surface direction.

[0071] The third layer 32 on the other side is arranged opposite to the third layer 31 on the other side of the thickness direction, spaced apart from the first layer 10 and the second layer 20. Furthermore, the third layer 32 on the other side has approximately the same thickness throughout the first direction. The third layer 32 on the other side has a side 35 that contacts the other side 26 of the second layer 22 on the other side, and another side 36 that is arranged opposite to the side 35 on the other side of the thickness direction, spaced apart from the side 35. The third layer 32 on the other side has a shape extending along the surface direction.

[0072] The third layer 32 on the other side and the third layer 31 on one side are symmetrical with respect to the imaginary surface passing through the center of the wiring 2 along the surface direction.

[0073] The thickness of the third layer 30 is the total thickness of the third layer 31 on one side and the third layer 32 on the other side, for example, 1 μm or more, preferably 5 μm or more, and for example, 1000 μm or less, preferably 800 μm or less.

[0074] The ratio of the thickness of the third layer 30 to the thickness of the magnetic layer 3 is, for example, 0.01 or more, preferably 0.05 or more, and also, for example, 0.5 or less, preferably 0.4 or less.

[0075] The ratio of the thickness of the third layer 30 to the thickness of the second layer 20 is, for example, 0.1 or more, preferably 0.2 or more, and also, for example, 100 or less, preferably 10 or less.

[0076] The fourth layer 40 independently has a fourth layer 41 on one side and a fourth layer 42 on the other side.

[0077] The fourth layer 41 on one side is in contact with the third layer 31 on the other side. Furthermore, the fourth layer 41 on one side has approximately the same thickness throughout the first direction. The fourth layer 41 on one side has another side 44 that is in contact with one side 33 of the third layer 31 on one side, and another side 43 that is spaced apart from the other side 44 on the thickness direction side. One side 43 of the fourth layer 41 on one side is exposed on the thickness direction side.

[0078] One side 43 has a flat surface along the first direction and the second direction.

[0079] The fourth layer 42 on the other side is disposed opposite to the fourth layer 41 on the other side, separated by the first layer 10, the second layer 20, and the third layer 30. Furthermore, the fourth layer 42 on the other side has approximately the same thickness throughout the first direction. The fourth layer 42 on the other side is in contact with the third layer 32 on the other side.

[0080] The fourth layer 42 on the other side has a side 45 that contacts the other side 36 of the third layer 32 on the other side, and another side 46 that is spaced apart from the side 45 and disposed opposite to it. The other side 46 is exposed on the other side in the thickness direction. The other side 46 has a flat surface along the first direction and the second direction.

[0081] The thickness of the fourth layer 40 is the total thickness of the fourth layer 41 on one side and the fourth layer 42 on the other side, for example, 1 μm or more, preferably 5 μm or more, and for example, 1000 μm or less, preferably 800 μm or less.

[0082] The ratio of the thickness of the fourth layer 42 to the thickness of the magnetic layer 3 is, for example, 0.01 or more, preferably 0.05 or more, and also, for example, 0.5 or less, preferably 0.4 or less.

[0083] The ratio of the thickness of the fourth layer 40 to the thickness of the third layer 30 is, for example, 0.1 or more, preferably 0.2 or more, and also, for example, 100 or less, preferably 10 or less.

[0084] The thickness of magnetic layer 3 is the total thickness of layer 10, layer 20, layer 30, and layer 40. The thickness of magnetic layer 3 is, for example, at least twice the radius of wiring 2, preferably at least three times, and also, for example, less than 20 times. Specifically, the thickness of magnetic layer 3 is, for example, at least 100 μm, preferably at least 200 μm, and also, for example, less than 3000 μm, preferably less than 1500 μm, more preferably less than 950 μm, further preferably less than 900 μm, and particularly preferably less than 850 μm. Furthermore, the thickness of magnetic layer 3 is the distance between one side and the other side of magnetic layer 3.

[0085] <Relative permeability of the magnetic layer>

[0086] In layers 10, 20, 30 and 40, in two adjacent layers, the relative permeability of the layer closer to wiring 2 is lower than that of the layer farther from wiring 2.

[0087] In magnetic layer 3, by appropriately changing, for example, the type, shape, and volume ratio of magnetic particles in each layer, the relative permeability of the layer closer to the wiring 2 can be set to be lower than the relative permeability of the layer farther from the wiring 2. The detailed adjustment (processing method) will be described using the first and second embodiments.

[0088] In addition, the relative permeability was measured at a frequency of 10 MHz.

[0089] Specifically, the relative permeability of layer 10 is lower than that of layer 20. The relative permeability of layer 20 is lower than that of layer 30. The relative permeability of layer 30 is lower than that of layer 40.

[0090] Furthermore, in the first layer 10, the second layer 20, the third layer 30, and the fourth layer 40, in two adjacent layers, the ratio R of the relative permeability of the layer closer to the wiring 2 to the relative permeability of the layer farther from the wiring 2 is, for example, 0.9 or less, preferably 0.7 or less, more preferably 0.5 or less, even more preferably 0.4 or less, particularly preferably 0.3 or less, and for example, 0.01 or more.

[0091] Specifically, the ratio R1 (relative permeability of the first layer 10 / relative permeability of the second layer 20) of the relative permeability of the first layer 10 to the relative permeability of the second layer 20 is 0.9 or less, preferably 0.7 or less, more preferably 0.5 or less, even more preferably 0.4 or less, particularly preferably 0.3 or less, and for example, 0.1 or more.

[0092] The ratio R2 (relative permeability of the second layer 20 / relative permeability of the third layer 30) of the relative permeability of the second layer 20 to the relative permeability of the third layer 30 is 0.9 or less, preferably 0.88 or less, more preferably 0.85 or less, and for example, 0.1 or more, preferably 0.2 or more, more preferably 0.4 or more, even more preferably 0.5 or more, even more preferably 0.6 or more, and particularly preferably 0.7 or more.

[0093] The ratio R3 (relative permeability of the third layer 30 / relative permeability of the fourth layer 40) of the relative permeability of the third layer 30 to the relative permeability of the fourth layer 40 is 0.9 or less, preferably 0.8 or less, more preferably 0.75 or less, even more preferably 0.7 or less, and for example, 0.1 or more, preferably 0.2 or more, more preferably 0.3 or more.

[0094] The ratios R1 to R3 mentioned above can all be the same, or they can be varied. Preferably, ratio R1 is smaller than ratio R2, and ratio R2 is smaller than ratio R3.

[0095] The ratio of R1 to R2 is, for example, 0.9 or less, preferably 0.8 or less, and more preferably 0.2 or more, preferably 0.3 or more, and more preferably 0.35 or more.

[0096] The ratio of R2 to R3 is, for example, 0.8 or less, preferably 0.7 or less, and also, for example, 0.3 or more, preferably 0.5 or more.

[0097] Furthermore, in the first layer 10, the second layer 20, the third layer 30, and the fourth layer 40, in two adjacent layers, the value D obtained by subtracting the relative permeability of the layer closer to the wiring 2 from the relative permeability of the layer farther from the wiring 2 is, for example, 5 or more, preferably 10 or more, more preferably 15 or more, and for example, 100 or less.

[0098] Specifically, the value D1 (relative permeability of the second layer 20 - relative permeability of the first layer 10) obtained by subtracting the relative permeability of the first layer 10 from the relative permeability of the second layer 20 is, for example, 5 or more, preferably 10 or more, more preferably 25 or more, and, for example, 50 or less.

[0099] The value D2 (relative permeability of the third layer 30 - relative permeability of the second layer 20) obtained by subtracting the relative permeability of the second layer 20 from the relative permeability of the third layer 30 is, for example, 5 or more, preferably 10 or more, and, for example, 50 or less, preferably 40 or less, and more preferably 30 or less.

[0100] The value D3 (relative permeability of the fourth layer 40 - relative permeability of the third layer 30) obtained by subtracting the relative permeability of the third layer 30 from the relative permeability of the fourth layer 40 is, for example, 10 or more, preferably 20 or more, and also, for example, 70 or less.

[0101] In addition, the values ​​D1 to D3 mentioned above can all be the same, or they can vary.

[0102] If the ratio R (including R1 to R3) and the difference D (the value obtained by subtraction) (including D1 to D3) of the relative permeability mentioned above are above the lower limit, the DC superposition characteristics of inductor 1 can be improved.

[0103] Each layer is defined by its relative permeability.

[0104] Specifically, in magnetic layer 3, the relative permeability of the region in contact with the peripheral surface of wiring 2 (corresponding to the region of the inner peripheral surface 13 of layer 10) is measured. Then, the relative permeability is continuously measured away from wiring 2, and the region up to the point where it has the same relative permeability as initially obtained is defined as layer 10. This definition is also applied sequentially to layer 20, layer 30, and layer 40. That is, regions with the same relative permeability are defined as one layer. Furthermore, in the above description, the relative permeability measurement is performed from the inner peripheral surface 13 of layer 10, but it can also be performed, for example, from one surface 43 of layer 40.

[0105] Furthermore, as described later, each layer consists of multiple magnetic sheets (described later) (see reference). Figure 2 In the case of an imaginary line, referring to the above definition, the relative permeability of the multiple magnetic sheets used to form each layer is the same.

[0106] In addition, in the manufacturing method described later, the relative permeability of the first sheet 51, the second sheet 52, the third sheet 53 and the fourth sheet 54 used to form the magnetic layer 3 can be measured in advance and used as the relative permeability of the first layer 10, the second layer 20, the third layer 30 and the fourth layer 40.

[0107] <Materials for the Magnetic Layer>

[0108] The magnetic layer 3 contains magnetic particles. Specifically, examples of materials for the magnetic layer 3 include magnetic compositions containing magnetic particles and binders.

[0109] Examples of magnetic materials constituting magnetic particles include soft magnetic materials and hard magnetic materials. From the viewpoint of inductance and DC superposition characteristics, soft magnetic materials are preferred.

[0110] Examples of soft magnetic materials include, for instance, a single metallic body containing one metallic element in its pure state, and an alloy body, for instance, a eutectic mixture (mixture) of one or more metallic elements (first metallic element) and one or more metallic elements (second metallic element) and / or non-metallic elements (carbon, nitrogen, silicon, phosphorus, etc.). These materials can be used alone or in combination.

[0111] As a single metallic body, examples include metallic monomers composed of only one metallic element (the first metallic element). The first metallic element can be appropriately selected from, for example, iron (Fe), cobalt (Co), nickel (Ni), and other metallic elements that can serve as the first metallic element in a soft magnetic body.

[0112] Furthermore, examples of single metallic bodies include, for instance, a core containing only one metallic element and a surface layer containing partially or completely inorganic and / or organic matter that modifies the surface of the core; organometallic compounds containing the first metallic element; and forms resulting from the decomposition (thermal decomposition, etc.) of inorganic metal compounds. More specifically, examples of the latter include iron powder (sometimes called carbonyl iron powder) resulting from the thermal decomposition of an organoiron compound containing iron as the first metallic element (specifically, carbonyl iron). Furthermore, the location of the layer containing inorganic and / or organic matter that modifies the portion containing only one metallic element is not limited to the surface described above. Moreover, there are no particular limitations on the organometallic compounds or inorganic metal compounds from which single metallic bodies can be obtained; rather, appropriate selections can be made from known or conventional organometallic compounds or inorganic metal compounds that can produce single metallic bodies with soft magnetic properties.

[0113] The alloy body is a fusion of one or more metallic elements (first metallic element) and one or more metallic elements (second metallic element) and / or non-metallic elements (carbon, nitrogen, silicon, phosphorus, etc.), and there are no particular restrictions as long as it can be used as an alloy body for soft magnetic materials.

[0114] The first metallic element is an essential element in the alloy, and examples include iron (Fe), cobalt (Co), and nickel (Ni). Furthermore, if the first metallic element is Fe, the alloy is an Fe-based alloy; if the first metallic element is Co, the alloy is a Co-based alloy; and if the first metallic element is Ni, the alloy is a Ni-based alloy.

[0115] The second metallic element is an auxiliary element (auxiliary component) contained in the alloy body and is compatible (eutectic) with the first metallic element. Examples include iron (Fe) (when the first metallic element is other than Fe), cobalt (Co) (when the first metallic element is other than Co), nickel (Ni) (when the first metallic element is other than Ni), chromium (Cr), aluminum (Al), silicon (Si), copper (Cu), silver (Ag), manganese (Mn), calcium (Ca), barium (Ba), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), molybdenum (Mo), tungsten (W), ruthenium (Ru), rhodium (Rh), zinc (Zn), gallium (Ga), indium (In), germanium (Ge), tin (Sn), lead (Pb), scandium (Sc), yttrium (Y), strontium (Sr), and various rare earth elements. These elements can be used alone or in combination of two or more.

[0116] Nonmetallic elements are elements (auxiliary components) that are contained in the alloy body as an auxiliary component, and are compatible (eutectic) with the first metallic element. Examples include boron (B), carbon (C), nitrogen (N), silicon (Si), phosphorus (P), and sulfur (S). These elements can be used alone or in combination of two or more.

[0117] Examples of Fe-based alloys as alloy bodies include, for example, magnetic stainless steel (Fe-Cr-Al-Si alloy) (including electromagnetic stainless steel), iron-silicon-aluminum (Fe-Si-Al alloy) (including super iron-silicon-aluminum), permalloy (Fe-Ni alloy), Fe-Ni-Mo alloy, Fe-Ni-Mo-Cu alloy, Fe-Ni-Co alloy, Fe-Cr alloy, Fe-Cr-Al alloy, Fe-Ni-Cr alloy, Fe-Ni-Cr-Si alloy, copper-silicon alloy (Fe-Cu-Si alloy), Fe-Si alloy, Fe-Si-B (-Cu-Nb) alloy, and Fe-B -Si-Cr alloys, Fe-Si-Cr-Ni alloys, Fe-Si-Cr alloys, Fe-Si-Al-Ni-Cr alloys, Fe-Ni-Si-Co alloys, Fe-N alloys, Fe-C alloys, Fe-B alloys, Fe-P alloys, ferrites (including stainless steel ferrites, as well as soft magnetic ferrites such as Mn-Mg ferrites, Mn-Zn ferrites, Ni-Zn ferrites, Ni-Zn-Cu ferrites, Cu-Zn ferrites, Cu-Mg-Zn ferrites, Cu-Mg-Zn ferrites), Perminde cobalt-based alloys (Fe-Co alloys), Fe-Co-V alloys, Fe-based amorphous alloys, etc.

[0118] Examples of Co-based alloys as alloy bodies include Co-Ta-Zr and cobalt (Co)-based amorphous alloys.

[0119] Examples of Ni-based alloys that serve as examples of alloy bodies include, for instance, Ni-Cr alloys.

[0120] Preferably, appropriate selection is made from these soft magnetic materials to satisfy the aforementioned relative permeability of each of the first layer 10, the second layer 20, the third layer 30, and the fourth layer 40.

[0121] The shape of the magnetic particles is not particularly limited, and can include anisotropic shapes such as roughly flat (plate-shaped), roughly needle-shaped (including roughly spindle (rugby ball)-shaped), and isotropic shapes such as roughly spherical, roughly granular, and roughly blocky. The shape of the magnetic particles is appropriately selected from the above shapes to satisfy the aforementioned relative permeability of each of the first layer 10, the second layer 20, the third layer 30, and the fourth layer 40.

[0122] The average maximum length of the magnetic particles is, for example, 0.1 μm or more, preferably 0.5 μm or more, and also, for example, 200 μm or less, preferably 150 μm or less. The average maximum length of the magnetic particles can be used as the median particle size of the magnetic particles for calculation.

[0123] The volume ratio (fill rate) of the magnetic composition of the magnetic particles is, for example, 10% or more, preferably 20% or more, and also, for example, 90% or less, preferably 80% or less.

[0124] By appropriately changing the type, shape, size, and volume ratio of the magnetic particles, the relative permeability of the first layer (10), the second layer (20), the third layer (30), and the fourth layer (40) satisfies the desired relationship.

[0125] Examples of adhesives include thermoplastic components such as acrylic resins and thermosetting components such as epoxy resin compositions. Acrylic resins include, for example, carboxyl-containing acrylate copolymers. Epoxy resin compositions include, for example, epoxy resins as the main agent (cresol phenolic varnish-type epoxy resins, etc.), epoxy resin curing agents (phenolic resins, etc.), and epoxy resin curing accelerators (imidazolium compounds, etc.).

[0126] As an adhesive, the thermoplastic component and the thermosetting component can be used separately or in combination, preferably in combination.

[0127] Furthermore, a more detailed method for processing the aforementioned magnetic composition is described in Japanese Patent Application Publication No. 2014-165363, etc.

[0128] <Inductor Manufacturing Method>

[0129] Reference Figure 2 This describes the manufacturing method of the inductor 1.

[0130] To manufacture the inductor 1, firstly, prepare the wiring 2.

[0131] Next, modulate two first pieces 51, two second pieces 52, two third pieces 53, and two fourth pieces 54.

[0132] The first piece 51, the second piece 52, the third piece 53 and the fourth piece 54 have relative permeability that satisfies the following formulas (1) to (3) by changing the type, shape and volume ratio of the magnetic particles they contain.

[0133] The relative permeability of the first piece 51 is less than the relative permeability of the second piece 52 (1)

[0134] The relative permeability of the second piece 52 is less than the relative permeability of the third piece 53 (2)

[0135] The relative permeability of the third piece (53) is less than the relative permeability of the fourth piece (54) (3)

[0136] Specifically, the processing method described above is used to modulate the first piece 51, the second piece 52, the third piece 53, and the fourth piece 54 containing magnetic particles, and to adjust the relative permeability of the first piece 51, the second piece 52, the third piece 53, and the fourth piece 54.

[0137] The first sheet 51, the second sheet 52, the third sheet 53, and the fourth sheet 54 are magnetic sheets used to form the first layer 10, the second layer 20, the third layer 30, and the fourth layer 40, respectively. The sheets are formed from the above-described magnetic composition and are formed into a plate shape extending in the surface direction.

[0138] Furthermore, depending on its use and purpose, a first piece 51 can be a single layer or can be composed of multiple layers (two or more layers) (see reference). Figure 2 The same applies to the other first piece 51, and so on to each second piece 52, each third piece 53, and each fourth piece 54.

[0139] Next, the first piece 51, the second piece 52, the third piece 53, and the fourth piece 54 are arranged in this order on each side of the thickness direction of the wiring 2. Specifically, two pieces 51 are arranged to sandwich the wiring 2. The second piece 52, the third piece 53, and the fourth piece 54 are arranged away from the wiring 2 in this order relative to the first piece 51.

[0140] Specifically, the fourth piece 54, the third piece 53, the second piece 52, the first piece 51, the wiring 2, the first piece 51, the second piece 52, the third piece 53, and the fourth piece 54 are arranged sequentially on the side facing the thickness direction.

[0141] Next, for example, they are hot-pressed. In hot pressing, for example, a flat plate is used.

[0142] Therefore, as Figure 1 As shown, the first piece 51, the second piece 52, the third piece 53 and the fourth piece 54 are deformed to form the first layer 10, the second layer 20, the third layer 30 and the fourth layer 40, respectively.

[0143] In detail, for example, the first piece 51 is deformed from a plate shape into a shape having a first arc portion 15 on one side and a first arc portion 16 on the other side and embedding wiring 2, thereby forming the first layer 10.

[0144] The second piece 52 is deformed from the plate shape to have a second arc portion 27 on one side and a second arc portion 28 on the other side and follows the shape of one side 11 and the other side 12 of the first layer 10, thereby forming the second layer 20.

[0145] In addition, the third piece 53 and the fourth piece 54 form the third layer 30 and the fourth layer 40, respectively.

[0146] Furthermore, when the magnetic composition contains thermosetting components, the magnetic composition is thermoset by heating simultaneously with hot pressing or by heating after hot pressing.

[0147] This forms a magnetic layer 3 with embedded wiring 2.

[0148] An inductor 1 is thus manufactured such that it has wiring 2 and magnetic layers 3, wherein in the first layer 10, the second layer 20, the third layer 30 and the fourth layer 40 of the magnetic layers 3, in two adjacent layers, the relative permeability of the layer closer to the wiring 2 is lower than the relative permeability of the layer farther from the wiring 2.

[0149] Furthermore, the inductor 1 has a magnetic layer 3 having a first layer 10, a second layer 20, a third layer 30, and a fourth layer 40 with the aforementioned relative permeability.

[0150] Therefore, the inductor 1 has excellent DC superposition characteristics.

[0151] The reason for this speculation is that the closer to wiring 2, the lower the relative permeability, and the less likely magnetic saturation will occur.

[0152] Furthermore, in this inductor 1, since the first layer 10 has an extension 17, the absolute amount of magnetic particles (filler) that contribute to improving the DC superposition characteristics increases, thus improving the DC superposition characteristics.

[0153] (Modified Example)

[0154] In the variations, the same reference numerals are used to label the same components and processes as in the first embodiment, and detailed descriptions are omitted. Furthermore, in the variations, except for the specifically described content, the same effects as in the first embodiment can be achieved. Moreover, the first embodiment and its variations can be appropriately combined.

[0155] In one of the above embodiments, such as Figure 1 As shown, the magnetic layer 3 has layers 1 to 4, but there is no particular limitation as long as the magnetic layer 3 has n layers (n is a positive number of 3 or more). For example, the magnetic layer 3 can have layers 1 to 30 but not a fourth layer 40 (in the embodiment where n is 3), which is not shown. Alternatively, the magnetic layer 3 can also have layers 1 to 5 (in the embodiment where n is 5).

[0156] Furthermore, in one of the above embodiments, such as Figure 1 As shown, wiring 2 has a roughly circular shape when viewed in cross-section, but the cross-sectional shape is not particularly limited. For example, it can also be roughly rectangular or elliptical when viewed in cross-section, which are not shown in the figure.

[0157] In one embodiment, the extension 17 extends from the peripheral surface of the wiring 2 to the first direction end face of the inductor 1. However, for example, the extension 17 may extend from the peripheral surface of the wiring 2 to the middle portion between the peripheral surface of the wiring 2 and the first direction end face of the inductor 1 without extending to the first direction end face of the inductor 1, which is not shown.

[0158] In one embodiment, the extension 17 is disposed in the first layer 10, but the extension 17 can also be disposed in any layer of the magnetic layer 3, for example, such as Figure 7 As shown, it can also be set on the second layer, 20.

[0159] like Figure 7 As shown, the first layer 10 has a generally annular shape when viewed in cross-section. The first layer 10 has an inner circumferential surface 13 and an outer circumferential surface 14 located radially outward relative to the inner circumferential surface 13.

[0160] The second layer 10 has a second arcuate portion 27 on one side, a second arcuate portion 28 on the other side, and an extension portion 17.

[0161] like Figure 8 As shown, the second layer 20, the third layer 30, and the fourth layer 40 can each be composed of one layer.

[0162] The second layer 20 is disposed on one side 11 of the first layer 10. The second layer 20 has another side 24 that is in contact with one side 11 of the first layer 10 and a side 23 that is opposite to the other side 24.

[0163] The third layer 30 is disposed on one side 23 of the second layer 20. The third layer 30 has another side 34 that is in contact with one side 23 of the second layer and a side 33 that is opposite to the other side 34.

[0164] The fourth layer 40 is disposed on one side 33 of the third layer 30. The fourth layer 40 has another side 44 that is in contact with one side 33 of the third layer 30 and another side 43 that is opposite to the other side 44.

[0165] In addition, the third layer 30 can have a roughly arc-shaped profile when viewed in section.

[0166] Furthermore, by appropriately changing the type, shape, and volume ratio of the magnetic particles in each layer of the magnetic layer 3, the relative permeability of the layers closer to the wiring 2 in the first layer 10, the second layer 20, the third layer 30, and the fourth layer 40 can be set to be lower than the relative permeability of the layers farther from the wiring 2.

[0167] (Detailed implementation methods)

[0168] In the following embodiments, reference will be made to the first and second embodiments. Figures 3-6 This describes a specific implementation method that, by changing the type, shape, volume ratio, etc. of the magnetic particles in each layer of magnetic layer 3, sets the relative permeability of the layer closer to the wiring 2 to be lower than that of the layer farther from the wiring 2.

[0169] In addition, Figures 1-2 Magnetic particles were not depicted in the text, but... Figures 3-6 In this diagram, the shape of the magnetic particles and the orientation of the second magnetic particle are depicted for ease of understanding. However, in... Figures 3-6 The text exaggerates the shape and orientation of the magnetic particles.

[0170] (First Embodiment)

[0171] Reference Figures 3-4 The inductor 1 of the first embodiment is described below.

[0172] like Figure 3 As shown, in the inductor 1 of the first embodiment, the first layer 10 contains a first magnetic particle 61 that is generally spherical in shape, and the second layer 20, the third layer 30 and the fourth layer 40 contain a second magnetic particle 62 that is generally flat in shape.

[0173] The first magnetic particles 61 are uniformly (isotropically) dispersed in the first layer 10 without orientation. The average particle size of the first magnetic particles 61 is, for example, 0.1 μm or more, preferably 0.5 μm or more, and also, for example, 100 μm or less, preferably 50 μm or less. As the magnetic material of the first magnetic particles 61, iron powder obtained from the thermal decomposition of an organoferric compound is preferably taken as an example, and carbonyl iron powder is more preferably taken as an example (the relative permeability at 10 MHz is, for example, 1.1 or more, preferably 3 or more, and also, for example, 25 or less, preferably 20 or less).

[0174] Since the first layer 10 contains a first magnetic particle 61 with a generally spherical shape, its relative permeability can be reliably set to be lower than that of the second layer 20, which contains a second magnetic particle 62 with a generally flat shape, as described later. Furthermore, the presence of the first magnetic particle 61 with a generally spherical shape gives the inductor 1 excellent inductance. Moreover, the presence of the first magnetic particle 61 with a generally spherical shape helps suppress magnetic saturation.

[0175] The second magnetic particle 62 is oriented along the direction of each of the second, third, and fourth layers 20, 30, and 40.

[0176] Specifically, the second magnetic particle 62 is oriented in the circumferential direction of the wiring 2 in the second arc portion 27 on one side and the second arc portion 28 on the other side of the second layer 20. Furthermore, the orientation of the second magnetic particle 62 in the circumferential direction is defined as the angle between the surface direction of the second magnetic particle 62 and the tangent line of the wiring 2 that is tangent to the circumferential surface opposite to the second magnetic particle 62 on the radially inner side being 15 degrees or less.

[0177] In addition, the second magnetic particle 62 is oriented along its surface direction in the third layer 30 and the fourth layer 40.

[0178] The average maximum length of the second magnetic particle 62 is, for example, 3.5 μm or more, preferably 10 μm or more, and also, for example, 200 μm or less, preferably 150 μm or less.

[0179] As the material for the second magnetic particle 62, an Fe-Si alloy (with a relative permeability of 25 or more at 10 MHz) is preferably used.

[0180] For example, if the types of second magnetic particles 62 in layers 20, 30, and 40 are the same, the volume ratio of the second magnetic particles 62 in layers 20, 30, and 40 can be adjusted. In this case, the volume ratio of the second magnetic particles 62 in the layers closer to the wiring 2 can be set to be lower than the volume ratio of the second magnetic particles 62 in the layers farther from the wiring 2.

[0181] Furthermore, when the volume ratio of the second magnetic particles 62 in layers 20, 30, and 40 is approximately the same, the types of the second magnetic particles 62 in layers 20, 30, and 40 are changed. In this case, the type of the second magnetic particles 62 is selected such that the relative permeability of the second magnetic particles 62 in the layer closer to the wiring 2 is lower than that of the second magnetic particles 62 in the layer farther from the wiring 2.

[0182] In addition, the volume ratio and relative permeability of the second magnetic particle 62 can also be changed.

[0183] To manufacture this inductor 1, such as Figure 4 As shown, a first sheet 51 containing a first magnetic particle 61 is prepared, along with a second sheet 52, a third sheet 53, and a fourth sheet 54 containing second magnetic particles 62 with the same or different relative permeabilities in the same or different volume ratios. The second magnetic particles 62 are oriented in the planar direction in each of the second sheet 52, the third sheet 53, and the fourth sheet 54.

[0184] Then, the wiring 2 and the first to fourth pieces 54 mentioned above are hot-pressed.

[0185] Thus, in the inductor 1, the first layer 10 contains a first magnetic particle 61 with a generally spherical shape, and the second layer 20, the third layer 30 and the fourth layer 40 have second magnetic particles 62 with a generally flat shape.

[0186] In this way, the first magnetic particles 61 are isotropically arranged in the first layer 10, while the second magnetic particles 62 can be oriented in the circumferential direction in the second arc portion 27 on one side and the second arc portion 28 on the other side of the second layer 20. Therefore, the inductor 1 has both excellent DC superposition characteristics and high inductance.

[0187] Furthermore, since the second magnetic particles 62, which are generally flat in shape and contained in the second layer 20, are oriented along the outer peripheral surface of the wiring 2, the inductance of the inductor 1 is excellent.

[0188] (Second Implementation)

[0189] Reference Figures 5-6 The inductor 1 of the second embodiment is described below.

[0190] like Figure 5 As shown, in the inductor 1 of the second embodiment, the first layer 10, the second layer 20, the third layer 30 and the fourth layer 40 all contain second magnetic particles 62 with a generally flat shape.

[0191] The second magnetic particle 62 has a generally flat shape. The second magnetic particle 62 is oriented in the direction along each of the first layer 10, the second layer 20, the third layer 30 and the fourth layer 40.

[0192] Specifically, the second magnetic particle 62 is oriented in the circumferential direction of the wiring 2 in the first arc portion 15 on one side and the first arc portion 16 on the other side of the first layer 10, and is oriented in the planar direction in the extension portion 17. Additionally, the second magnetic particle 62 is oriented in the circumferential direction of the wiring 2 in the second arc portion 27 on one side and the second arc portion 28 on the other side. On the other hand, the second magnetic particle 62 is oriented along its planar direction in the third layer 30 and the fourth layer 40.

[0193] For example, when the types of the second magnetic particles 62 in layers 10, 20, 30, and 40 are the same, the volume ratio of the second magnetic particles 62 in layers 10, 20, 30, and 40 is adjusted. In this case, the volume ratio of the second magnetic particles 62 in the layers closer to the wiring 2 is set to be lower than the volume ratio of the second magnetic particles 62 in the layers farther from the wiring 2. Specifically, the ratio of the volume ratio of the second magnetic particles 62 in layer 10 to the volume ratio of the second magnetic particles 62 in layer 20 is, for example, less than 1, preferably 0.9 or less, more preferably 0.8 or less, and, for example, 0.5 or more, further preferably 0.6 or more. The same applies to the volume ratio of the second magnetic particles 62 in layers 30 and 40.

[0194] Furthermore, when the volume ratio of the second magnetic particles 62 in layers 10, 20, 30, and 40 is approximately the same, the type of the second magnetic particles 62 in layers 10, 20, 30, and 40 is changed. In this case, the type of the second magnetic particles 62 is selected such that the relative permeability of the second magnetic particles 62 in layers closer to the wiring 2 is lower than that in layers farther from the wiring 2.

[0195] Alternatively, two methods can be used: changing the volume ratio of the second magnetic particle 62 and changing the relative permeability of the second magnetic particle 62.

[0196] From the perspective that the adjustment range of the relative permeability of the first layer 10 to the fourth layer 40 is larger, the method of changing the relative permeability of the second magnetic particle 62 is preferred over the method of changing the volume ratio of the second magnetic particle 62.

[0197] On the other hand, from the viewpoint of ensuring excellent productivity, it is preferable to change the volume ratio of the second magnetic particle 62 rather than the method of changing the relative permeability of the second magnetic particle 62.

[0198] Furthermore, in both the first and second embodiments, the first embodiment is preferred. Compared to the second embodiment, the first embodiment can reliably and easily set the relative permeability of the first layer 10 to be lower than the relative permeability of the second layer 20.

[0199] In order to manufacture the inductor 1 of the second embodiment, such as Figure 6 As shown, a first sheet 51, a second sheet 52, a third sheet 53, and a fourth sheet 54 are prepared to contain second magnetic particles 62 with the same or different relative permeabilities in the same or different volume ratios. The second magnetic particles 62 are oriented in the planar direction in each of the first sheet 51, the second sheet 52, the third sheet 53, and the fourth sheet 54.

[0200] Then, the wiring 2 and the first to fourth pieces 54 mentioned above are hot-pressed.

[0201] (Another variation)

[0202] Alternatively, all layers 10 through 40 may contain, for example, isotropic magnetic particles, specifically, a first magnetic particle 61 of approximately spherical shape, which is not illustrated.

[0203] Example

[0204] The following examples and comparative examples further illustrate the present invention. However, the present invention is not limited to any particular example or comparative example. Furthermore, the specific numerical values ​​of mixing ratios (including proportions), physical property values, parameters, etc., used in the following description can be replaced with the corresponding upper limits (defined as values ​​"below" or "less than") or lower limits (defined as values ​​"above" or "exceeding") of the mixing ratios (including proportions), physical property values, parameters, etc., described in the "Detailed Embodiments" above.

[0205] Modulation Example 1

[0206] <Preparation of Adhesive>

[0207] Prepare the adhesive according to the processing method described in Table 1.

[0208] Example 1

[0209] <Example of manufacturing an inductor based on the first embodiment>

[0210] First, prepare wiring 2 with a radius of 130μm. The radius of conductor 4 is 115μm, and the thickness of insulating film 5 is 15μm.

[0211] The first piece 51, the second piece 52, the third piece 53, and the fourth piece 54 were manufactured in accordance with the types and filling rates of magnetic particles recorded in Table 2.

[0212] Prepare 4 sheets with a thickness of 60 μm for sheet 1 (51). Prepare 8 sheets with a thickness of 130 μm for sheet 2 (52). Prepare 8 sheets with a thickness of 60 μm for sheet 3 (53). Prepare 4 sheets with a thickness of 100 μm for sheet 4 (54).

[0213] Then, two fourth pieces 54, four third pieces 53, four second pieces 52, two first pieces 51, wiring 2, two first pieces 51, four second pieces 52, four third pieces 53, and two fourth pieces 54 are arranged sequentially on the side facing the thickness direction.

[0214] Next, they are hot-pressed using a flat plate press to form magnetic layer 3.

[0215] Thus, an inductor 1 having wiring 2 and a magnetic layer 3 embedded therein is manufactured. The thickness of the inductor 1 is 975 μm.

[0216] Example 2 to Comparative Example 1

[0217] The processing method of the magnetic sheet was changed according to Tables 3 to 6. Otherwise, the inductor 1 was manufactured in the same manner as in Example 1.

[0218] Furthermore, the inductor 1 in Embodiment 2 corresponds to the second embodiment (specifically, the embodiment in which the types of magnetic particles in each layer of the magnetic layer are changed).

[0219] Furthermore, the inductor 1 in Embodiment 3 corresponds to the second embodiment (specifically, the embodiment in which the content ratio (fill rate) of magnetic particles in each layer of the magnetic layer is changed).

[0220] In addition, the inductor 1 in Embodiment 4 is a second embodiment, which is an embodiment that changes both the type and the proportion (fill rate) of magnetic particles in each layer of the magnetic layer.

[0221] <Evaluation>

[0222] Evaluate the following items and record the results in Tables 2 to 7.

[0223] <Relative permeability>

[0224] The relative permeability of the first piece 51 of Examples 1 to Comparative Examples 1, the second piece 52 of Examples 1 to 4, the third piece 53 of Examples 1 to 4, and the fourth piece 54 of Examples 1 and 3 were measured using an impedance analyzer (manufactured by Agilent Technologies, "4291B") of the magnetic material testing apparatus.

[0225] <DC superposition characteristics>

[0226] Using an impedance analyzer (manufactured by Kuwagi Electronics Co., Ltd., "65120B") equipped with a DC bias test device and a DC bias power supply, a current of 10A was flowed through the wire 4 of the inductor 1 of Examples 1 to Comparative Examples 1, and the inductance descent rate was measured to evaluate the DC superposition characteristics.

[0227] The inductance decay rate is calculated based on the following formula.

[0228] [Inductance without DC bias current - Inductance with DC bias current] / [Inductance with DC bias current] × 100 (%)

[0229] [Table 1]

[0230]

[0231] [Table 2]

[0232]

[0233] [Table 3]

[0234]

[0235] [Table 4]

[0236]

[0237] [Table 5]

[0238]

[0239] [Table 6]

[0240]

[0241] [Table 7]

[0242]

[0243] Furthermore, the above-described invention is provided as an illustrative embodiment of the present invention, but this is merely illustrative and not a limiting interpretation. Variations of the invention that will be apparent to those skilled in the art are included in the foregoing claims.

[0244] Industrial availability

[0245] Inductors are used in electronic devices, etc.

[0246] Explanation of reference numerals in the attached figures

[0247] 1. Inductor; 2. Wiring; 3. Magnetic layer; 4. Conductor; 5. Insulating film; 10. First layer; 20. Second layer; 30. Third layer; 40. Fourth layer; 17. Extension; 61. First magnetic particle (approximately spherical magnetic particle); 62. Second magnetic particle (approximately flat magnetic particle).

Claims

1. An inductor, characterized in that, This inductor has the following characteristics: Wiring, the wiring having conductors and an insulating film disposed on the entire circumference of the conductors; and A magnetic layer in which the wiring is embedded. The magnetic layer contains magnetic particles. The magnetic layer has a first layer in contact with the peripheral surface of the wiring, a second layer in contact with the surface of the first layer, ..., an nth layer in contact with the surface of the (n-1)th layer (n is a positive number of 3 or more). The magnetic particles contained in the first layer are spherical in shape. The magnetic particles contained in the second to nth layers have a flat shape. In the magnetic layer, the relative permeability of the layer closer to the wiring is lower than that of the layer farther from the wiring.

2. The inductor according to claim 1, characterized in that, The wiring has a generally circular shape when viewed in cross-section.

3. The inductor according to claim 2, characterized in that, Any of the layers from the 2nd to the nth layer has a common center with the wiring and is approximately arc-shaped when viewed in cross-section.

4. The inductor according to claim 1, characterized in that, Any of the first to nth layers has an extension portion extending from the wiring in a direction orthogonal to the direction of the wiring extension and the thickness direction of the magnetic layer.

5. The inductor according to claim 1, characterized in that, At least the magnetic particles contained in the second layer are oriented along the outer peripheral surface of the wiring.

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