Inductor

Abstract

An inductor 1 comprises: a plurality of wires 2; a first magnetic layer 3 containing first magnetic particles 31 and covering the plurality of wires 2; a second magnetic layer 4 laminated on the first magnetic layer 3 and containing second magnetic particles 41 having a relative permeability higher than that of the first magnetic particles 31; and a third magnetic layer 5 laminated on the second magnetic layer 4 and containing third magnetic particles 51 having a relative permeability higher than that of the second magnetic particles 41. The relative permeability of the second magnetic layer 4 is higher than the relative permeability of the first magnetic layer 3, and the relative permeability of the third magnetic layer 5 is higher than the relative permeability of the second magnetic layer 4. The thickness T3 of the third magnetic layer 5 is greater than the respective thicknesses T1 and T2 of the first magnetic layer 3 and the second magnetic layer 4.

Description

inductor

[0001] The present invention relates to an inductor.

[0002] 2. Description of the Related Art Conventionally, as an inductor component built into a wiring board, there is known an inductor component that includes a magnetic substrate having a through hole and a through-hole conductor formed in the through hole of the magnetic substrate (see Patent Document 1 below).

[0003] Japanese Patent Application Laid-Open No. 2019-129278

[0004] Further improvements in the performance of inductor components built into wiring boards are desired.

[0005] In this regard, in the inductor described in Patent Document 1, since a through-hole conductor is formed in a through hole of a magnetic substrate, it is difficult to optimize the structure of the magnetic substrate, which makes it difficult to improve the performance of the inductor component.

[0006] The present invention provides an inductor that can improve performance.

[0007] The present invention [1] includes an inductor comprising: a plurality of wirings extending in a first direction and aligned in a second direction perpendicular to the first direction; a first magnetic layer containing first magnetic particles and covering the plurality of wirings in a third direction perpendicular to both the first direction and the second direction; a second magnetic layer stacked on the first magnetic layer in the third direction and containing second magnetic particles having a higher relative magnetic permeability than the first magnetic particles; and a third magnetic layer stacked on the second magnetic layer in the third direction and containing third magnetic particles having a higher relative magnetic permeability than the second magnetic particles, wherein the relative magnetic permeability of the second magnetic layer is higher than that of the first magnetic layer, the relative magnetic permeability of the third magnetic layer is higher than that of the second magnetic layer, and the thickness of the third magnetic layer is greater than that of each of the first magnetic layer and the second magnetic layer.

[0008] According to this configuration, a plurality of magnetic layers (first magnetic layer, second magnetic layer, and third magnetic layer) having different properties are arranged around the wiring.

[0009] Specifically, the wiring is covered with a first magnetic layer containing first magnetic particles, and a second magnetic layer having a relative permeability higher than that of the first magnetic layer is arranged around the first magnetic layer, and a third magnetic layer having a relative permeability higher than that of the second magnetic layer and thicker than the first and second magnetic layers is arranged around that.

[0010] Therefore, the DC bias characteristics are ensured by the first magnetic layer having a low relative magnetic permeability, while the inductance can be increased by the second magnetic layer and the third magnetic layer.

[0011] As a result, the performance of the inductor can be improved.

[0012] The present invention [2] includes the inductor according to the above [1], wherein the thickness of the first magnetic layer is thinner than the thickness of each of the second magnetic layer and the third magnetic layer.

[0013] With this configuration, by making the first magnetic layer thinner than the second and third magnetic layers, it is possible to achieve a compact design while maintaining inductance. More specifically, it is possible to ensure high inductance per unit length of the wiring, while also achieving a balance between the DC bias characteristics and inductance.

[0014] The present invention [3] includes the inductor of [1] or [2] above, wherein the first magnetic particles are made of iron and have a spherical shape, the second magnetic particles are made of an Fe—Si alloy and have a flat shape, and the third magnetic particles are made of an Fe—Si—Al alloy and have a flat shape.

[0015] With this configuration, the first magnetic layer ensures DC bias characteristics, while the second and third magnetic layers can further increase inductance.

[0016] The present invention [4] includes the inductor according to the above [3], wherein the second magnetic particles are made of a heat-treated Fe—Si alloy, and the third magnetic particles are made of a heat-treated Fe—Si—Al alloy.

[0017] With this configuration, the inductance can be further increased by the second magnetic layer and the third magnetic layer.

[0018] The present invention [5] includes the inductor of any one of [1] to [4] above, wherein the inductor has a first surface and a second surface opposite the first surface in the first direction, and each of the plurality of wirings has, in the first direction, a first end exposed at the first surface and a second end exposed at the second surface.

[0019] According to this configuration, the conductor pattern of the wiring board can be connected to the first end and the second end of the wiring.

[0020] The present invention [6] includes the inductor of any one of [1] to [5] above, wherein the wiring comprises a conductor and an insulating layer disposed between the conductor and the first magnetic layer and covering the circumferential surface of the conductor.

[0021] The present invention [7] includes the inductor according to any one of the above [1] to [6], further comprising a cover layer laminated on the third magnetic layer.

[0022] According to this configuration, the cover layer can protect the magnetic layers (first magnetic layer, second magnetic layer, and third magnetic layer).

[0023] The present invention [8] includes the inductor according to the above [7], wherein the cover layer contains fourth magnetic particles.

[0024] With this configuration, the fourth magnetic particles in the cover layer can also increase the inductance.

[0025] The present invention [9] includes an inductor according to any one of the above [1] to [8], which has a first surface, a second surface opposite to the first surface in the first direction, a side surface disposed between the first surface and the second surface in the first direction, and a corner portion at which the first surface or the second surface is connected to the side surface, and the corner portion has an arc shape.

[0026] With this configuration, chipping of the corners can be prevented.

[0027] According to the inductor of the present invention, the performance of the inductor can be improved.

[0028] FIG. 1 is a perspective view of an inductor according to one embodiment of the present invention. FIG. 2A is a cross-sectional view of the inductor shown in FIG. 1, taken along line A-A in FIG. 2B. FIG. 2B is a cross-sectional view of the inductor shown in FIG. 1 at the center in the first direction. FIG. 3 is an enlarged view of a portion surrounded by a dashed line in FIG. 2B. FIG. 4 is a cross-sectional view of the inductor shown in FIG. 2B taken along line B-B. FIG. 5 is an explanatory diagram illustrating a mode of use of the inductor shown in FIG. 1. FIG. 6 is an explanatory diagram illustrating a method of manufacturing the inductor shown in FIG. 1.

[0029] 1. Inductor The inductor 1 will be described with reference to FIGS.

[0030] As shown in FIG. 1 , the inductor 1 has a substantially rectangular parallelepiped shape. In a first direction, the inductor 1 has a first surface S1 and a second surface S2 opposite the first surface S1. The first direction is the direction in which the wiring 2 extends. The wiring 2 will be described later. The inductor 1 further has a plurality of side surfaces S3, S4, S5, and S6, a plurality of corners C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, and C12, and a plurality of tops V1, V2, V3, V4, V5, V6, V7, and V8.

[0031] The first surface S1 is one side of the inductor 1 in the first direction. The first surface S1 extends in the second and third directions. The second direction is the direction in which the multiple wirings 2 are arranged. The second direction is perpendicular to the first direction. The third direction is perpendicular to both the first and second directions.

[0032] The second surface S2 is the other surface of the inductor 1 in the first direction. The second surface S2 is disposed apart from the first surface S1 in the first direction. The second surface S2 extends in the second direction and the third direction.

[0033] Sides S3, S4, S5, and S6 are arranged between the first surface S1 and the second surface S2 in the first direction. Side S3 is one side of the inductor 1 in the second direction. Side S3 extends in the first direction and the third direction. Side S4 is the other side of the inductor 1 in the second direction. Side S4 is arranged away from side S3 in the second direction. Side S4 extends in the first direction and the third direction. Side S5 is one side of the inductor 1 in the third direction. Side S5 extends in the first direction and the second direction. Side S6 is the other side of the inductor 1 in the third direction. Side S6 is arranged away from side S5 in the third direction. Side S6 extends in the first direction and the second direction.

[0034] The first surface S1 and the side surface S3 are connected at a corner C1. The corner C1 extends in the third direction. The second surface S2 and the side surface S3 are connected at a corner C2. The corner C2 extends in the third direction. The first surface S1 and the side surface S4 are connected at a corner C3. The corner C3 extends in the third direction. The second surface S2 and the side surface S4 are connected at a corner C4. The corner C4 extends in the third direction. The first surface S1 and the side surface S5 are connected at a corner C5. The corner C5 extends in the second direction. The second surface S2 and the side surface S5 are connected at a corner C6. The corner C6 extends in the second direction. The first surface S1 and the side surface S6 are connected at a corner C7. The corner C7 extends in the second direction. The second surface S2 and the side surface S6 are connected at a corner C8. The corner C8 extends in the second direction. The side surfaces S3 and S5 are connected at a corner C9. The corner C9 extends in the first direction. The side surfaces S4 and S5 are connected at a corner C10. The corner C10 extends in the first direction. The side surfaces S3 and S6 are connected at a corner C11. The corner C11 extends in the first direction. The side surfaces S4 and S6 are connected at a corner C12. The corner C12 extends in the first direction.

[0035] Each of the corners C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, and C12 has an arc shape, or in other words, each of the corners C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, and C12 is chamfered.

[0036] By each of the corners C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, and C12 having an arc shape, chipping of each of the corners C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, and C12 can be prevented.

[0037] Corners C1, C5, and C9 are connected at vertex V1. Corners C2, C6, and C9 are connected at vertex V2. Corners C3, C5, and C10 are connected at vertex V3. Corners C4, C6, and C10 are connected at vertex V4. Corners C1, C7, and C11 are connected at vertex V5. Corners C2, C8, and C11 are connected at vertex V6. Corners C3, C7, and C12 are connected at vertex V7. Corners C4, C8, and C12 are connected at vertex V8.

[0038] Each of the apexes V1, V2, V3, V4, V5, V6, V7, and V8 has an arc shape, that is, each of the apexes V1, V2, V3, V4, V5, V6, V7, and V8 is chamfered.

[0039] By each of the apexes V1, V2, V3, V4, V5, V6, V7, and V8 having an arc shape, chipping of each of the apexes V1, V2, V3, V4, V5, V6, V7, and V8 can be prevented.

[0040] As shown in FIG. 2A, the length L1 of the inductor 1 in the first direction is, for example, 1.5 mm or less, preferably 1.3 mm or less, and for example, 0.7 mm or more.

[0041] The length L2 of the inductor 1 in the second direction is not limited and is, for example, 10 mm or less, preferably 5 mm or less, and is, for example, 3 mm or more.

[0042] As shown in FIG. 2B, the length L3 of the inductor 1 in the third direction is, for example, 2.0 mm or less, preferably 1.5 mm or less, and for example, 0.5 mm or more.

[0043] The inductance (Ls) of the inductor 1 at 10 MHz is, for example, 5 nH / mm or more, or preferably 10 nH / mm or more. There is no upper limit to the inductance (Ls).

[0044] The inductance is measured by the method described in the examples below.

[0045] The DC bias characteristic of the inductor 1 can be evaluated by the inductance reduction rate. The inductance reduction rate of the inductor 1 is, for example, 30% or less, preferably 25% or less. There is no lower limit to the inductance reduction rate.

[0046] The inductance reduction rate is measured by the method described in the examples below.

[0047] The Q value of the inductor 1 at 10 MHz is, for example, 15 or more, or preferably 20 or more. There is no upper limit to the Q value.

[0048] The Q value is measured by the method described in the Examples below.

[0049] As shown in FIGS. 2B and 3, the inductor 1 includes a plurality of wirings 2, a first magnetic layer 3, two second magnetic layers 4, two third magnetic layers 5, and a cover layer 6.

[0050] (1) Wiring As shown in FIG. 2A , each of the multiple wirings 2 extends in a first direction. Each of the multiple wirings 2 has a first end 2A and a second end 2B in the first direction. The first end 2A and the second end 2B can be used as external terminals of the inductor 1. Specifically, the first end 2A is exposed on the first surface S1. The first end 2A is exposed only from the first surface S1. That is, the first end 2A is not exposed on the second surface S2 or the side surfaces S3, S4, S5, and S6. By being exposed on the first surface S1, the first end 2A can be used as an external terminal of the inductor 1. Similarly, the second end 2B is exposed on the second surface S2. The second end 2B is exposed only from the second surface S2. That is, the second end 2B is not exposed on the first surface S1 or the side surfaces S3, S4, S5, and S6. The second end 2B is exposed to the second surface S2 and can be used as an external terminal of the inductor 1.

[0051] The first end 2A does not have to be exposed on the first surface S1. An electrode (an electrode usable as an external terminal of the inductor 1) that is electrically connected to the first end 2A may be provided on the first surface S1. The electrode may include at least one layer selected from the group consisting of a copper-containing layer, a nickel-containing layer, a tin-containing layer, and a gold-containing layer. The electrode may protrude outward from the first surface S1 in the first direction. Similarly, the second end 2B does not have to be exposed on the second surface S2. An electrode (an electrode usable as an external terminal of the inductor 1) that is electrically connected to the second end 2B may be provided on the second surface S2.

[0052] As shown in Fig. 2B, the multiple wires 2 are arranged in the center of the inductor 1 in the third direction. The multiple wires 2 are aligned in the second direction. The multiple wires 2 are arranged at intervals from each other in the second direction. Each of the multiple wires 2 has a substantially cylindrical shape. The diameter of the wires 2 is, for example, 150 µm to 350 µm, preferably 200 µm to 300 µm.

[0053] As shown in FIG. 3 , each of the plurality of wirings 2 includes a conductive wire 21 and an insulating layer 22 .

[0054] The conductor 21 extends in a first direction. The conductor 21 has a generally cylindrical shape. Examples of materials for the conductor 21 include metal conductors. Examples of metal conductors include copper, silver, gold, aluminum, nickel, and alloys thereof. A preferred material for the conductor 21 is copper. The conductor 21 may have a single-layer structure or a multi-layer structure. The multi-layer conductor 21 has, for example, a core made of the above-mentioned metal conductor (e.g., copper) and a plating layer (e.g., nickel plating layer) covering the surface of the core.

[0055] The diameter of the conducting wire 21 is, for example, 100 μm to 300 μm, or preferably 150 μm to 250 μm.

[0056] The insulating layer 22 covers the outer surface of the conductive wire 21. The insulating layer 22 is disposed between the conductive wire 21 and the first magnetic layer 3. The insulating layer 22 insulates the conductive wire 21 from the first magnetic layer 3.

[0057] Examples of materials for the insulating layer 22 include insulating resins. Examples of insulating resins include polyvinyl formal, polyester, polyesterimide, polyamide (including nylon), polyimide, polyamideimide, and polyurethane. The insulating resins may be used alone or in combination of two or more. The insulating layer 22 may be composed of a single layer or multiple layers. Preferably, two or more types of insulating resins are used in combination. In other words, the insulating layer 22 preferably has a multi-layer structure. If the insulating layer 22 has a multi-layer structure, it is possible to improve the insulation properties and electromigration resistance.

[0058] The insulating layer 22 has a thickness of, for example, 5 μm to 30 μm, or preferably 10 μm to 20 μm.

[0059] (2) First Magnetic Layer As shown in FIG. 2B, the first magnetic layer 3 is disposed in the center of the inductor 1 in the third direction. The first magnetic layer 3 extends in the second direction. As shown in FIG. 2A, the first magnetic layer 3 extends in the first direction. The first magnetic layer 3 extends in the first direction from the first surface S1 to the second surface S2 of the inductor 1.

[0060] As shown in FIG. 2B , the multiple wirings 2 are disposed within the first magnetic layer 3. The first magnetic layer 3 covers the multiple wirings 2 in the second and third directions. The first magnetic layer 3 covers the entire periphery of each of the multiple wirings 2. The first magnetic layer 3 does not cover the first end 2A (see FIG. 2A ) and the second end 2B (see FIG. 2A ) of each of the multiple wirings 2.

[0061] As shown in FIG. 3, the first magnetic layer 3 has a first portion 3A and a second portion 3B.

[0062] The first portion 3A overlaps with the wiring 2 in the third direction. The first portion 3A covers the wiring 2 in the third direction. The first portion 3A extends along the circumferential surface of the wiring 2. The first portion 3A has a substantially arc shape.

[0063] The second portion 3B is disposed between the two wirings 2 in the second direction. The second portion 3B covers the wirings 2 in the second direction. The second portion 3B does not overlap with the wirings 2 in the third direction. The second portion 3B is continuous with the first portion 3A and extends in the second direction.

[0064] The relative permeability of the first magnetic layer 3 is lower than the relative permeability of the second magnetic layer 4 and the relative permeability of the third magnetic layer 5. The relative permeability is measured at a frequency of 10 MHz.

[0065] The thickness T1 of the first magnetic layer 3 is smaller than the thickness T2 of the second magnetic layer 4 and the thickness T3 of the third magnetic layer 5 .

[0066] The "thickness T1 of the first magnetic layer 3" is half the total thickness T0 of the first magnetic layer 3 in the cross section of the end of the inductor 1 in the second direction, as shown in Fig. 4. The cross section shown in Fig. 4 corresponds to line B-B in Fig. 2B, and extends in the third direction without passing through the wiring 2.

[0067] Furthermore, the "thickness T2 of the second magnetic layer 4" is the thickness of the second magnetic layer 4 in the cross section of the end of the inductor 1 in the second direction (the cross section shown in FIG. 4).

[0068] Furthermore, the "thickness T3 of the third magnetic layer 5" is the thickness of the third magnetic layer 5 in the cross section of the end of the inductor 1 in the second direction (the cross section shown in FIG. 4).

[0069] That is, the first magnetic layer 3 has the lowest relative magnetic permeability among the first magnetic layer 3, the second magnetic layer 4 and the third magnetic layer 5, and is also the thinnest.

[0070] Therefore, it is possible to obtain an inductor that has a high inductance value and good DC superposition characteristics.

[0071] Specifically, the relative permeability of the first magnetic layer 3 is, for example, 5 to 30, or preferably 7 to 20.

[0072] The thickness T1 of the first magnetic layer 3 is in the range of, for example, 10 μm to 100 μm, or preferably 30 μm to 70 μm.

[0073] If the sum of the thickness T1 of the first magnetic layer 3, the thickness T2 of the second magnetic layer 4, and the thickness T3 of the third magnetic layer 5 is 100%, the thickness T1 of the first magnetic layer 3 is, for example, 3% to 20%, preferably 6% to 15%.

[0074] As shown in FIG. 3, the first magnetic layer 3 contains a binder 30 and first magnetic particles 31 .

[0075] Examples of the binder 30 include a thermosetting resin and a thermoplastic resin.

[0076] Examples of thermosetting resins include epoxy resins, phenolic resins, melamine resins, thermosetting polyimide resins, unsaturated polyester resins, polyurethane resins, silicone resins, etc. From the viewpoints of adhesiveness, heat resistance, etc., epoxy resins and phenolic resins are preferred.

[0077] Examples of thermoplastic resins include acrylic resins, ethylene-vinyl acetate copolymers, polycarbonate resins, polyamide resins (such as 6-nylon and 6,6-nylon), thermoplastic polyimide resins, saturated polyester resins (such as PET and PBT), etc. Acrylic resins are preferred.

[0078] Preferably, the binder 30 is a combination of a thermosetting resin and a thermoplastic resin, and more preferably, a combination of an acrylic resin, an epoxy resin, and a phenolic resin.

[0079] The first magnetic particles 31 are not oriented but are uniformly (isotropically) dispersed in the first magnetic layer 3. Examples of materials for the first magnetic particles 31 include soft magnetic materials and hard magnetic materials. From the viewpoint of inductance, the soft magnetic material is preferable as the material for the first magnetic particles 31.

[0080] Examples of soft magnetic materials include single metal bodies containing one type of metal element in a pure substance state, and alloy bodies that are eutectic bodies (mixtures) of one or more types of metal elements (first metal elements) and one or more types of metal elements (second metal elements) and / or non-metal elements (carbon, nitrogen, silicon, phosphorus, etc.). These can be used alone or in combination.

[0081] The single metal body may be, for example, a metal element consisting of only one type of metal element (first metal element). The first metal element may be selected from iron (Fe), cobalt (Co), nickel (Ni), and other metal elements that can be contained as the first metal element in a soft magnetic body.

[0082] Furthermore, examples of the single metal body include a core containing only one type of metal element and a surface layer containing an inorganic and / or organic substance that modifies part or all of the surface of the core, such as a form obtained by decomposing (e.g., thermally decomposing) an organometallic compound or inorganic metal compound containing the first metal element. More specifically, the latter form includes iron powder (sometimes referred to as carbonyl iron powder) obtained by thermally decomposing an organoiron compound (e.g., carbonyl iron) containing iron as the first metal element. The location of the layer containing the inorganic and / or organic substance that modifies the portion containing only one type of metal element is not limited to the surface as described above. The organometallic compound or inorganic metal compound from which the single metal body can be obtained is not particularly limited and can be appropriately selected from known or commonly used organometallic compounds or inorganic metal compounds that can be used to obtain a single metal body of a soft magnetic material.

[0083] The alloy body is a eutectic of one or more metal elements (first metal elements) and one or more metal elements (second metal elements) and / or non-metal elements (carbon, nitrogen, silicon, phosphorus, etc.), and is not particularly limited as long as it can be used as an alloy body of a soft magnetic material.

[0084] The first metal element is an essential element in the alloy body, and examples thereof include iron (Fe), cobalt (Co), nickel (Ni), etc. If the first metal element is Fe, the alloy body is an Fe-based alloy, if the first metal element is Co, the alloy body is a Co-based alloy, and if the first metal element is Ni, the alloy body is a Ni-based alloy.

[0085] The second metallic element is an element (secondary component) secondarily contained in the alloy body, and is a metallic element that is compatible (eutectic) with the first metallic element, and examples thereof 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 (B), and the like. Examples of the rare earth elements include Ba (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 may be used alone or in combination of two or more.

[0086] The non-metallic element is an element (secondary component) secondarily contained in the alloy body, and is a non-metallic element that is compatible (eutectic) with the first metallic element, such as boron (B), carbon (C), nitrogen (N), silicon (Si), phosphorus (P), sulfur (S), etc. These may be used alone or in combination of two or more.

[0087] Examples of Fe-based alloys that are examples of alloy bodies include magnetic stainless steel (Fe—Cr—Al—Si alloy) (including electromagnetic stainless steel), sendust (Fe—Si—Al alloy) (including super sendust), 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, silicon copper (Fe—Cu—Si alloy), Fe—Si alloy, Fe—Si—B(—Cu—Nb) alloy, Fe—B—Si—Cr alloy, Fe—S Examples of the ferrite include an i-Cr-Ni alloy, an Fe-Si-Cr alloy, an Fe-Si-Al-Ni-Cr alloy, an Fe-Ni-Si-Co alloy, an Fe-N alloy, an Fe-C alloy, an Fe-B alloy, an Fe-P alloy, ferrite (including stainless steel ferrite, and soft ferrites such as Mn-Mg ferrite, Mn-Zn ferrite, Ni-Zn ferrite, Ni-Zn-Cu ferrite, Cu-Zn ferrite, and Cu-Mg-Zn ferrite), permendur (an Fe-Co alloy), an Fe-Co-V alloy, and an Fe-based amorphous alloy.

[0088] Examples of the alloy body, such as a Co-based alloy, include Co-Ta-Zr and cobalt (Co)-based amorphous alloys.

[0089] An example of the alloy body, a Ni-based alloy, is a Ni-Cr alloy.

[0090] The material of the first magnetic particles 31 is selected from the above-mentioned soft magnetic materials and hard magnetic materials so as to impart a desired relative magnetic permeability to the first magnetic layer 3 .

[0091] The first magnetic particles 31 are preferably made of iron. Examples of the first magnetic particles 31 made of iron include iron powder obtained by thermal decomposition of an organic iron compound, and more preferably carbonyl iron powder (relative permeability at 10 MHz: for example, 1.1 or more, preferably 3 or more, and for example, 25 or less, preferably 20 or less). The first magnetic particles 31 preferably have a spherical shape. When the first magnetic particles 31 are spherical, the inductance value of the inductor 1 can be increased. Furthermore, when the first magnetic particles 31 are spherical, the fluidity of the first magnetic layer 3 can be ensured during the manufacture of the inductor 1. Therefore, during the manufacture of the inductor 1, the formation of voids around the wiring 2 can be suppressed, and the wiring 2 can be suppressed from being pushed by the first magnetic layer 3 and being bent. As a result, the inductor 1 can be easily manufactured. Furthermore, when the first magnetic particles 31 are spherical, magnetic saturation can be suppressed.

[0092] The average particle diameter (D50) of the first magnetic particles 31 is, for example, 0.1 μm or more, preferably 0.5 μm or more, more preferably 2 μm or more, and for example, 100 μm or less, preferably 50 μm or less, more preferably 10 μm or less.

[0093] The "average particle size (D50)" refers to the volume-based average particle size (D50) measured using a laser diffraction particle size distribution analyzer (LS 13 320, manufactured by Beckman Coulter, Inc.).

[0094] The volume ratio of the first magnetic particles 31 in the first magnetic layer 3 is, for example, 50% to 70% by volume, or preferably 55% to 65% by volume.

[0095] (3) Second Magnetic Layer As shown in FIG. 3 , the second magnetic layer 4 is stacked on the first magnetic layer 3 in the third direction. Specifically, one second magnetic layer 4A of the two second magnetic layers 4 is disposed on one side of the first magnetic layer 3 in the third direction, and the other second magnetic layer 4B of the two second magnetic layers 4 is disposed on the other side of the first magnetic layer 3 in the third direction. One second magnetic layer 4A covers one surface of the first magnetic layer 3 in the third direction. The other second magnetic layer 4B covers the other surface of the first magnetic layer 3 in the third direction. The second magnetic layer 4 extends in the second direction. Also, as shown in FIG. 4 , the second magnetic layer 4 extends in the first direction. The second magnetic layer 4 extends from the first surface S1 to the second surface S2 of the inductor 1 in the first direction.

[0096] The relative permeability of the second magnetic layer 4 is lower than that of the third magnetic layer 5 and higher than that of the first magnetic layer 3. The thickness T2 of the second magnetic layer 4 is thinner than the thickness T3 of the third magnetic layer 5 and thicker than the thickness T1 of the first magnetic layer 3.

[0097] Specifically, the relative permeability of the second magnetic layer 4 is, for example, 30 to 70, or preferably 45 to 65.

[0098] The thickness T2 of the second magnetic layer 4 is in the range of, for example, 20 μm to 200 μm, or preferably 30 μm to 150 μm.

[0099] If the sum of the thickness T1 of the first magnetic layer 3, the thickness T2 of the second magnetic layer 4, and the thickness T3 of the third magnetic layer 5 is 100%, the thickness T2 of the second magnetic layer 4 is, for example, 5% to 30%, preferably 8% to 20%.

[0100] As shown in FIG. 3, the second magnetic layer 4 contains a binder 40 and second magnetic particles 41 .

[0101] The binder 40 may be the same resin as the binder 30 described above.

[0102] The second magnetic particles 41 have a higher relative magnetic permeability than the first magnetic particles 31. The second magnetic particles 41 are oriented in the second magnetic layer 4 in the direction in which the second magnetic layer 4 extends. In other words, the second magnetic particles 41 are oriented in the second direction and the first direction in the second magnetic layer 4.

[0103] The above-described soft magnetic materials and hard magnetic materials can be used as the material of the second magnetic particles 41. The material of the second magnetic particles 41 is selected from the above-described soft magnetic materials and hard magnetic materials so as to impart a desired relative magnetic permeability to the second magnetic layer 4.

[0104] The second magnetic particles 41 are preferably made of an Fe—Si alloy. More preferably, the second magnetic particles 41 are made of a heat-treated Fe—Si alloy. The second magnetic particles 41 preferably have a flat shape. This allows the flat second magnetic particles 41 to be oriented along the outer periphery of the wiring 2, thereby increasing the inductance of the inductor 1.

[0105] The average particle diameter (D50) of the second magnetic particles 41 is, for example, 3.5 μm or more, preferably 10 μm or more, more preferably 30 μm or more, and for example, 200 μm or less, preferably 150 μm or less, more preferably 45 μm or less.

[0106] The volume ratio of the second magnetic particles 41 in the second magnetic layer 4 is, for example, 40% to 60% by volume, or preferably 45% to 55% by volume.

[0107] (4) Third Magnetic Layer As shown in FIG. 3 , the third magnetic layer 5 is stacked on the second magnetic layer 4 in the third direction. Specifically, one third magnetic layer 5A of the two third magnetic layers 5 is disposed on one side of one second magnetic layer 4A in the third direction, and the other third magnetic layer 5B of the two third magnetic layers 5 is disposed on the other side of the other second magnetic layer 4B in the third direction. One third magnetic layer 5A covers one second magnetic layer 4A. The other third magnetic layer 5B covers the other second magnetic layer 4B. The third magnetic layer 5 extends in the second direction. Also, as shown in FIG. 4 , the third magnetic layer 5 extends in the first direction. The third magnetic layer 5 extends from the first surface S1 to the second surface S2 of the inductor 1 in the first direction.

[0108] The relative permeability of the third magnetic layer 5 is higher than the relative permeability of the first magnetic layer 3 and the relative permeability of the second magnetic layer 4. The thickness T3 of the third magnetic layer 5 is greater than the thickness T1 of the first magnetic layer 3 and the thickness T2 of the second magnetic layer 4.

[0109] Specifically, the relative permeability of the third magnetic layer 5 is, for example, 70 to 150, or preferably 90 to 130.

[0110] The thickness T3 of the third magnetic layer 5 is in the range of, for example, 100 μm to 500 μm, or preferably 200 μm to 400 μm.

[0111] If the sum of the thickness T1 of the first magnetic layer 3, the thickness T2 of the second magnetic layer 4, and the thickness T3 of the third magnetic layer 5 is 100%, the thickness T3 of the third magnetic layer 5 is, for example, 30% to 95%, preferably 50% to 90%.

[0112] As shown in FIG. 3, the third magnetic layer 5 contains a binder 50 and third magnetic particles 51 .

[0113] The binder 50 may be the same resin as the binder 30 described above.

[0114] The third magnetic particles 51 have a higher relative magnetic permeability than the second magnetic particles 41. The third magnetic particles 51 are oriented in the extension direction of the third magnetic layer 5 in the third magnetic layer 5. In other words, the third magnetic particles 51 are oriented in the second direction and the first direction in the third magnetic layer 5.

[0115] That is, the first magnetic particles 31 are isotropically dispersed in the first magnetic layer 3, while the second magnetic particles 41 are oriented in the second and first directions in the second magnetic layer 4, and the third magnetic particles 51 are oriented in the second and first directions in the third magnetic layer 5. Therefore, the inductor 1 can achieve both excellent DC bias characteristics and high inductance.

[0116] The above-described soft magnetic materials and hard magnetic materials can be used as the material of the third magnetic particles 51. The material of the third magnetic particles 51 is selected from the above-described soft magnetic materials and hard magnetic materials so as to impart a desired relative magnetic permeability to the third magnetic layer 5.

[0117] The third magnetic particles 51 are preferably made of an Fe—Si—Al alloy. More preferably, the third magnetic particles 51 are made of a heat-treated Fe—Si—Al alloy. The third magnetic particles 51 have a flat shape. This allows the flat-shaped third magnetic particles 51 to be oriented along the outer periphery of the wiring 2, thereby increasing the inductance of the inductor 1.

[0118] The average particle diameter (D50) of the third magnetic particles 51 is, for example, 3.5 μm or more, preferably 10 μm or more, more preferably 30 μm or more, and for example, 200 μm or less, preferably 150 μm or less, more preferably 60 μm or less.

[0119] The volume ratio of the fifth magnetic particles 51 in the third magnetic layer 5 is, for example, 45 to 65% by volume, or preferably 50 to 60% by volume.

[0120] (5) Cover Layer The cover layer 6 is disposed on the side surfaces S5 and S6 (see FIG. 1) of the inductor 1. The cover layer 6 is not disposed on the first surface S1 (see FIG. 1), the second surface S2 (see FIG. 1), or the side surfaces S3 and S4 (see FIG. 1). The cover layer 6 is laminated on the third magnetic layer 5 in the third direction. The cover layer 6 is made of a resin 60. The resin 60 of the cover layer 6 may be the same as or different from the binder of each of the magnetic layers described above. Preferably, the hardness of the cover layer 6 is higher than the hardness of each of the magnetic layers described above. A preferred example of the resin 60 is an epoxy resin. The cover layer 6 may contain at least one of fourth magnetic particles 61 and non-magnetic particles. The fourth magnetic particles 61 may be the same as the first magnetic particles 31.

[0121] When the cover layer 6 contains the fourth magnetic particles 61 , the volume ratio of the fourth magnetic particles 61 in the cover layer 6 may be the same as the volume ratio of the first magnetic particles 31 in the first magnetic layer 3 .

[0122] 2. Usage of the Inductor Next, usage of the inductor 1 will be described with reference to FIG.

[0123] 5, the inductor 1 is built into the circuit board C. Specifically, the inductor 1 is disposed in an opening in the base material S of the circuit board C. With the inductor 1 built into the circuit board C, the wiring 2 extends in the thickness direction of the circuit board C. A first end 2A of the wiring 2 is connected to a conductor pattern P1 on one side of the thickness direction of the circuit board C. A second end 2B of the wiring 2 is connected to a conductor pattern P2 on the other side of the thickness direction of the circuit board C.

[0124] 3. Inductor Manufacturing Method Next, a method for manufacturing the inductor 1 will be described with reference to FIG.

[0125] The manufacturing method of the inductor 1 includes a sheet manufacturing step, a laminating step, a cutting step, and a polishing step.

[0126] (1) Sheet Manufacturing Process In the sheet manufacturing process, as shown in FIG. 6, a first magnetic sheet 11, a second magnetic sheet 12, a third magnetic sheet 13, and a cover sheet 14 are produced.

[0127] The first magnetic sheet 11 is a sheet for producing the first magnetic layer 3. The first magnetic sheet 11 is formed in a sheet shape from a composition containing, for example, a thermosetting binder 30 (specifically, a combination of a thermosetting resin and a thermoplastic resin) and first magnetic particles 31. The first magnetic sheet 11 is in an uncured state. When the first magnetic particles 31 are spherical, the first magnetic particles 31 are uniformly dispersed in the first magnetic sheet 11.

[0128] The second magnetic sheet 12 is a sheet for producing the second magnetic layer 4. The second magnetic sheet 12 is formed in a sheet shape from a composition containing, for example, a thermosetting binder 40 (specifically, a combination of a thermosetting resin and a thermoplastic resin) and second magnetic particles 41. The second magnetic sheet 12 is in an uncured state. When the second magnetic particles 41 have a flat shape, the second magnetic particles 41 are oriented in the direction in which the second magnetic sheet 12 extends.

[0129] The third magnetic sheet 13 is a sheet for producing the third magnetic layer 5. The third magnetic sheet 13 is formed in a sheet shape from a composition containing, for example, a thermosetting binder 50 (specifically, a combination of a thermosetting resin and a thermoplastic resin) and third magnetic particles 51. The third magnetic sheet 13 is in an uncured state. When the third magnetic particles 51 have a flat shape, the third magnetic particles 51 are oriented in the direction in which the third magnetic sheet 13 extends.

[0130] The cover sheet 14 is a sheet for producing the cover layer 6. The cover sheet 14 is formed in a sheet shape from a composition containing, for example, an epoxy resin 60 and fourth magnetic particles 61.

[0131] (2) Stacking process Next, in the stacking process, the wiring 2 is sandwiched between two first magnetic sheets 11, the second magnetic sheet 12 is stacked on top of the first magnetic sheet 11, and the third magnetic sheet 13 is stacked on top of the second magnetic sheet 12.

[0132] Note that multiple identical magnetic sheets may be stacked to adjust the thickness of each magnetic layer to the desired thickness. For example, multiple first magnetic sheets 11 may be stacked to adjust the thickness of the first magnetic layer 3 to the desired thickness. In this case, the second magnetic sheet 12 is stacked on top of the stack of multiple first magnetic sheets 11. Multiple second magnetic sheets 12 and third magnetic sheets 13 may also be stacked.

[0133] Next, the obtained laminate (a laminate of the wiring 2 and each magnetic sheet) is heat-pressed. At this time, a release sheet or cushion film (not shown) can be used between the laminate and the heat press device as appropriate. For example, a flat plate press is used for the heat press. Preferably, an isostatic press is used for the heat press. By isostatic pressing, each magnetic sheet and the wiring 2 can be isotropically heat-pressed, thereby improving the conformability between the wiring 2 and each magnetic sheet. For example, the method described in JP 2021-028929 A can be used for the isostatic press.

[0134] By hot pressing, the first magnetic layer 3 is formed from the first magnetic sheet 11, the second magnetic layer 4 is formed from the second magnetic sheet 12, and the third magnetic layer 5 is formed from the third magnetic sheet 13.

[0135] The cover sheet 14 is then placed on top and heat-pressed again to form the cover layer 6. When forming the cover layer 6, the heat-pressing is preferably performed without using isostatic pressing. By performing the heat-pressing without using isostatic pressing, a smooth cover layer 6 can be placed on the side surfaces S5, S6 of the inductor 1, thereby improving the smoothness of the side surfaces S5, S6 of the inductor 1. The cover sheet 14 can also be heat-pressed simultaneously with the magnetic sheets.

[0136] As a result, a sheet having the wiring 2 and the magnetic layers (first magnetic layer 3, second magnetic layer 4, and third magnetic layer 5) covering the wiring 2 is completed.

[0137] (3) Cutting Step Next, in the cutting step, the inductor 1 described above is cut out from the sheet obtained in the lamination step. Cutting can be performed by punching, blade dicing using a dicing blade, or laser dicing. Covering the magnetic layer with the cover layer 6 can prevent the cut-out inductor 1 from having poor appearance.

[0138] (4) Polishing Step Next, in the polishing step, the cut inductor 1 is polished. Examples of polishing methods include barrel polishing and blast polishing. In the case of barrel polishing, the corners C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, and C12 and the peaks V1, V2, V3, V4, V5, V6, V7, and V8 are rounded. In the case of blast polishing, the corners C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, and C12 and the peaks V1, V2, V3, V4, V5, V6, V7, and V8 are not rounded, and the edges of each side can be maintained.

[0139] This completes the manufacturing of the inductor 1.

[0140] 4. Effects and Benefits (1) According to the inductor 1, as shown in FIG. 3, a plurality of magnetic layers (first magnetic layer 3, second magnetic layer 4, and third magnetic layer 5) having different properties are arranged around the wiring 2.

[0141] Specifically, the wiring 2 is covered with a first magnetic layer 3 containing first magnetic particles 31, and a second magnetic layer 4 having a relative permeability higher than that of the first magnetic layer 3 is arranged around the first magnetic layer 3, and a third magnetic layer 5 having a relative permeability higher than that of the second magnetic layer 4 and thicker than the first magnetic layer 3 and the second magnetic layer 4 is arranged around that.

[0142] Therefore, the DC bias characteristics are ensured by the first magnetic layer 3 having a low relative magnetic permeability, while the inductance can be increased by the second magnetic layer 4 and the third magnetic layer 5 .

[0143] As a result, the performance of the inductor 1 can be improved.

[0144] (2) In the inductor 1, as shown in FIG. 4, the thickness T1 of the first magnetic layer 3 is smaller than the thickness T2 of the second magnetic layer 4 and the thickness T3 of the third magnetic layer 5.

[0145] This allows the inductor 1 to be made smaller while ensuring the inductance of the inductor 1 .

[0146] (3) According to the inductor 1, the first magnetic particles 31 are made of iron and have a spherical shape, the second magnetic particles 41 are made of an Fe—Si alloy and have a flat shape, and the third magnetic particles 51 are made of an Fe—Si—Al alloy and have a flat shape.

[0147] Therefore, the first magnetic layer 3 ensures the DC bias characteristics, while the second magnetic layer 4 and the third magnetic layer 5 can further increase the inductance of the inductor 1 .

[0148] (4) In the inductor 1, the second magnetic particles 41 are made of a heat-treated Fe—Si alloy, and the third magnetic particles 51 are made of a heat-treated Fe—Si—Al alloy.

[0149] Therefore, the second magnetic layer 4 and the third magnetic layer 5 can further increase the inductance of the inductor 1 .

[0150] (5) According to the inductor 1, as shown in FIG. 2A, each of the wirings 2 has, in the first direction, a first end 2A exposed to the first surface S1 and a second end 2B exposed to the second surface S2.

[0151] Therefore, as shown in FIG. 5, the conductor pattern P1 can be connected to the first end 2A of the wiring 2, and the conductor pattern P2 can be connected to the second end 2B of the wiring 2.

[0152] This allows the inductor 1 to be built into the circuit board C.

[0153] (6) As shown in FIG. 3, the inductor 1 includes the cover layer 6 laminated on the third magnetic layer 5 .

[0154] Therefore, the magnetic layers (first magnetic layer 3, second magnetic layer 4, and third magnetic layer 5) can be protected by the cover layer 6. Furthermore, since the magnetic layers are covered by the cover layer 6, the occurrence of poor appearance of the cut-out inductor 1 can be suppressed.

[0155] (7) According to the inductor 1, as shown in FIG. 3, the cover layer 6 contains the fourth magnetic particles 61.

[0156] Therefore, the fourth magnetic particles 61 in the cover layer 6 can also increase the inductance of the inductor 1 .

[0157] (8) According to the inductor 1, the corners C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, and C12 have an arc shape.

[0158] Therefore, chipping of the corners C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, and C12 can be prevented.

[0159] Next, the present invention will be described based on examples and comparative examples. The present invention is not limited by the following examples. Furthermore, specific numerical values ​​of physical properties, parameters, etc. used in the following description can be replaced with the upper limit values ​​(numerical values ​​defined as "equal to or less than") or lower limit values ​​(numerical values ​​defined as "equal to or greater than") of the corresponding physical properties, parameters, etc. described in the above "Description of the Invention."

[0160] 1. Manufacturing of Inductor (1) Example First, 24.5 parts by mass of epoxy resin (main component), 24.5 parts by mass of phenol resin (hardening agent), 1 part by mass of imidazole compound (hardening accelerator), and 50 parts by mass of acrylic resin (thermoplastic resin) were mixed to prepare a binder for the magnetic sheet. The density of the binder for the magnetic sheet was 1.092 g / cm ３ It was.

[0161] Next, the obtained binder for the magnetic sheet was blended with the magnetic particles listed in Table 1 in the volume ratios (theoretical values ​​based on the blending) listed in Table 1, and mixed to produce the first magnetic sheet, the second magnetic sheet, and the third magnetic sheet (sheet manufacturing process).

[0162] Next, multiple wires with a diameter of 260 μm were arranged horizontally at intervals and sandwiched between first and second magnetic sheets, and a second magnetic sheet was placed on top of the first magnetic sheet, followed by a third magnetic sheet on top of the second magnetic sheet, to obtain a laminate.

[0163] Next, the obtained laminate was isostatically pressed using a dry laminator (manufactured by Nikkiso Co., Ltd.) as an isostatic pressing device under the conditions described in paragraphs

[0183] to

[0186] of JP-A-2021-028929.

[0164] Next, a cover sheet (epoxy resin) was placed on the laminate after isostatic pressing, and then plate-pressed.

[0165] As a result, an inductor sheet was completed, which had a plurality of wirings, magnetic layers (first magnetic layer, second magnetic layer, and third magnetic layer) covering the wirings, and a cover layer (lamination step).

[0166] The density of the magnetic particles, the volume ratio of the magnetic particles in each magnetic layer (actual measured value), the density of each magnetic layer, and the relative permeability of each magnetic layer are shown in Table 1. The thickness of each magnetic layer is shown in Table 2. The thickness of each magnetic layer was adjusted by stacking multiple identical magnetic sheets.

[0167] Next, inductors were cut out from the resulting inductor sheet using a dicing blade (cutting step).

[0168] Next, the cut inductor was subjected to barrel polishing (polishing step).

[0169] Inductors were obtained in the same manner as in Example 1, except that the thickness of each magnetic layer was adjusted to the thickness shown in Table 2 by changing the number of magnetic sheets.

[0170]

[0171] Spherical Fe (carbonyl iron powder, D50: 5 μm) Flat FeSi (Fe-Si alloy, D50: 40 μm) Flat FeSiAl (Fe-Si-Al alloy, D50: 45 μm)

[0172]

[0173] 2. Performance Evaluation of Inductors (1) Inductance The "inductance at a frequency of 10 MHz" of the inductor 1 in each example and comparative example was measured. The measured inductances are shown in Table 2. An impedance analyzer (manufactured by Agilent, "4291B") was used for the measurement.

[0174] (2) DC Superposition Characteristics Using an impedance analyzer (manufactured by Kuwaki Electronics Co., Ltd., "65120B") equipped with a DC bias test fixture and a DC bias power supply, a current of 5 A was passed through the wiring 2 (i.e., the conductor 21) of the inductor 1 of each example and each comparative example, and the inductance reduction rate was measured to evaluate the DC superposition characteristics.

[0175] The inductance reduction rate was calculated based on the following formula: The calculated inductance reduction rates are shown in Table 2. The lower the inductance reduction rate, the better the DC bias characteristics.

[0176] [Inductance without DC bias current applied - Inductance with DC bias current applied] / [Inductance with DC bias current applied] x 100 (%) (3) Q Factor The Q factor of the inductor 1 in each example and comparative example was measured. The measured Q factors are shown in Table 2. An impedance analyzer (manufactured by Agilent, "4291B") was used for the measurement.

[0177] In Examples 1 to 4, high inductance per unit length of wiring is ensured, and the DC bias characteristics and inductance are balanced, while the Q value is also ensured. On the other hand, in Comparative Example 1, the inductance reduction rate is large and the DC bias characteristics are not satisfied. In Comparative Example 2, the inductance value is insufficient. Note that the above invention is provided as an exemplary embodiment of the present invention, but this is merely an example and should not be interpreted as limiting. Modifications of the present invention that are obvious to those skilled in the art are included within the scope of the claims below.

[0178] The inductor of the present invention can be used, for example, as a built-in component in a circuit board.

[0179] REFERENCE SIGNS LIST 1 inductor 2 wiring 2A first end 2B second end 3 first magnetic layer 4 second magnetic layer 5 third magnetic layer 6 cover layer 21 conducting wire 22 insulating layer 31 first magnetic particle 41 second magnetic particle 51 third magnetic particle 61 fourth magnetic particle S1 first surface S2 second surface S3 side C1 corner T1 thickness of first magnetic layer T2 thickness of second magnetic layer T3 thickness of third magnetic layer

Claims

1. An inductor comprising: a plurality of wirings extending in a first direction and aligned in a second direction perpendicular to the first direction; a first magnetic layer containing first magnetic particles and covering the plurality of wirings in a third direction perpendicular to both the first and second directions; a second magnetic layer stacked on the first magnetic layer in the third direction and containing second magnetic particles having a higher relative magnetic permeability than the first magnetic particles; and a third magnetic layer stacked on the second magnetic layer in the third direction and containing third magnetic particles having a higher relative magnetic permeability than the second magnetic particles, wherein the relative permeability of the second magnetic layer is higher than that of the first magnetic layer, the relative permeability of the third magnetic layer is higher than that of the second magnetic layer, and the thickness of the third magnetic layer is greater than that of each of the first and second magnetic layers.

2. The inductor according to claim 1, wherein the thickness of said first magnetic layer is thinner than the thickness of each of said second magnetic layer and said third magnetic layer.

3. The inductor of claim 1, wherein the first magnetic particles are made of iron and have a spherical shape, the second magnetic particles are made of an Fe-Si alloy and have a flat shape, and the third magnetic particles are made of an Fe-Si-Al alloy and have a flat shape.

4. The inductor according to claim 3, wherein the second magnetic particles are made of a heat-treated Fe-Si alloy, and the third magnetic particles are made of a heat-treated Fe-Si-Al alloy.

5. The inductor according to claim 1, wherein the inductor has a first surface and a second surface opposite the first surface in the first direction, and each of the plurality of wirings has a first end exposed to the first surface and a second end exposed to the second surface in the first direction.

6. The inductor according to claim 1, wherein the wiring comprises: a conductive wire; and an insulating layer disposed between the conductive wire and the first magnetic layer and covering the circumferential surface of the conductive wire.

7. The inductor of claim 1, further comprising a cover layer laminated on said third magnetic layer.

8. The inductor of claim 7, wherein the cover layer contains fourth magnetic particles.

9. The inductor according to claim 1, comprising: a first surface; a second surface opposite the first surface in the first direction; a side surface disposed between the first surface and the second surface in the first direction; and a corner portion connecting the first surface or the second surface to the side surface, the corner portion having an arc shape.

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