inductor

Abstract

To provide an inductor having a high inductance and an excellent DC superposition characteristic, and furthermore having an excellent Q value.SOLUTION: An inductor 1 comprises: first wiring 21 and second wiring 22; a first magnetic layer 31 containing a nearly spherical magnetic particle; a second magnetic layer 51 containing a nearly flat magnetic particle; and a third magnetic layer 71 containing the nearly flat magnetic particle. A relative magnetic permeability of the second magnetic layer 51 and that of the third magnetic layer 71 are higher than the relative magnetic permeability of the first magnetic layer 31. A fourth surface 54 of the first magnetic layer 31 includes a second recessed portion 60. A sixth surface 74 of the third magnetic layer 71 includes a fourth recessed portion 80.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an inductor. [Background technology]

[0002] BACKGROUND ART Conventionally, an inductor has been known that includes a plurality of conductors and a magnetic layer that covers the conductors (see, for example, Patent Document 1).

[0003] In Patent Document 1, an inductor is obtained by stacking a ferrite green sheet on top of another ferrite green sheet on which a plurality of conductors are arranged, and then firing these. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-144526 Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, inductors are required to have high inductance, excellent DC bias characteristics, and an excellent Q value.

[0006] However, the inductor described in Patent Document 1 cannot satisfy the above requirements.

[0007] The present invention provides an inductor that has high inductance, excellent DC bias characteristics, and an excellent Q value. [Means for solving the problem]

[0008] The present invention [1] provides a first magnetic layer having first wiring and second wiring adjacent to each other with a gap therebetween, a first surface continuing in a surface direction, a second surface spaced apart from the first surface in a thickness direction and continuing in the surface direction, and an inner surface located between the first surface and the second surface and contacting an outer surface of the first wiring and an outer surface of the second wiring, the first magnetic layer containing substantially spherical magnetic particles and a resin; a second magnetic layer having a third surface contacting the first surface and a fourth surface spaced apart from the third surface in the thickness direction and containing substantially flat magnetic particles and a resin; and a third magnetic layer having a fifth surface contacting the second surface and a sixth surface spaced apart from the fifth surface in the thickness direction and containing substantially flat magnetic particles and a resin, the magnetic constant is higher than the relative magnetic permeability of the first magnetic layer, the third surface has a first recess recessed from a first opposing portion opposing the first wiring in the thickness direction and a second opposing portion opposing the second wiring in the thickness direction, between the first opposing portion and the second opposing portion; the fourth surface has a second recess recessed from a third opposing portion opposing the first opposing portion in the thickness direction and a fourth opposing portion opposing the second opposing portion in the thickness direction, between the fourth opposing portion and the third opposing portion; the fifth surface has a third recess recessed from a fifth opposing portion opposing the first wiring in the thickness direction and a sixth opposing portion opposing the second wiring in the thickness direction, between the fifth opposing portion and the sixth opposing portion; and the sixth surface has a fourth recess recessed from a seventh opposing portion opposing the fifth opposing portion in the thickness direction and an eighth opposing portion opposing the second opposing portion in the thickness direction.

[0009] This inductor includes a first magnetic layer containing substantially spherical magnetic particles, and second and third magnetic layers containing substantially flat magnetic particles. Furthermore, the relative permeability of each of the second and third magnetic layers is higher than that of the first magnetic layer. Therefore, this inductor has high inductance and excellent DC bias characteristics.

[0010] Furthermore, since the second magnetic layer has the first recess and the second recess, in the region of the second magnetic layer surrounded by the first recess and the second recess, the magnetic particles having a substantially flat shape can be oriented to the first recess and the second recess. Furthermore, since the third magnetic layer has the third recess and the fourth recess, in the region of the third magnetic layer surrounded by the third recess and the fourth recess, the magnetic particles having a substantially flat shape can be oriented to the third recess and the fourth recess. Therefore, an excellent Q value can be obtained.

[0011] Therefore, this inductor has a high inductance, excellent DC bias characteristics, and an excellent Q value.

[0012] The present invention [2] includes the inductor according to [1], wherein the length L1 between the first opposing portion and the first wiring, the length L2 between the second opposing portion and the second wiring, and the depth L3 of the first recess satisfy the following formulas (1) and (2), and the length L4 between the third opposing portion and the first wiring, the length L5 between the fourth opposing portion and the second wiring, and the depth L6 of the second recess satisfy the following formulas (3) and (4). L3 / L1≧0.2 (1) L3 / L2≧0.2 (2) L6 / L4≧0.2 (3) L6 / L5≧0.2 (4)

[0013] The present invention [3] includes the inductor according to [1] or [2], wherein the depth L3 of the first recess and the depth L7 of the second recess satisfy the following formula (5), and the depth L6 of the third recess and the depth L8 of the fourth recess satisfy the following formula (6). L7 / L3≧0.3 (5) L8 / L6≧0.3 (6)

[0014] The present invention [4] includes the inductor according to any one of [1] to [3], wherein the length L1 between the first opposing portion and the first wiring and the thickness direction length L9 of the first wiring satisfy the following formula (7), the length L2 between the second opposing portion and the second wiring and the thickness direction length L10 of the second wiring satisfy the following formula (8), the length L4 between the third opposing portion and the first wiring and the length L9 of the first wiring satisfy the following formula (9), and the length L5 between the fourth opposing portion and the second wiring and the length L10 of the second wiring satisfy the following formula (10). L1 / L9≧0.1 (7) L2 / L10≧0.1 (8) L4 / L9≧0.1 (9) L5 / L10≧0.1 (10) [Effects of the Invention]

[0015] The inductor of the present invention has high inductance, excellent DC bias characteristics, and an excellent Q value. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a cross-sectional view of an embodiment of an inductor of the present invention. [Figure 2] FIG. 2 is a cross-sectional view illustrating magnetic particles contained in the first magnetic layer, the second magnetic layer, and the third magnetic layer of the inductor shown in FIG. [Figure 3] FIG. 3 shows the first step of preparing a heat press device in the method for manufacturing an inductor. [Figure 4] FIG. 4, following FIG. 3, shows a third step in the inductor manufacturing method, in which the magnetic sheet, the first wiring, and the second wiring are set in a heat press device. [Figure 5] 5, following FIG. 4, shows a fourth step in the inductor manufacturing method, in which the outer frame member is brought into close contact with the first mold to form a first sealed space, and then the first sealed space is depressurized to form a depressurized space. [Figure 6]FIG. 6, following FIG. 5, shows a fifth step in the inductor manufacturing method, in which the inner frame member is pressed against the first die to form a second sealed space with a reduced pressure atmosphere. [Figure 7] FIG. 7, following FIG. 6, shows a sixth step in the inductor manufacturing method, in which the magnetic sheet, the first wiring, and the second wiring are hot-pressed. [Figure 8] FIG. 8 shows a process of forming through holes in the inductor removed from the heat press device in FIG. [Figure 9] FIG. 9 shows a cross-sectional view of a modified example of the inductor shown in FIG. 1 (an embodiment in which the inductor further includes a functional layer). DETAILED DESCRIPTION OF THE INVENTION

[0017] <One embodiment> An embodiment of an inductor of the present invention will be described with reference to FIGS.

[0018] The inductor 1 has a generally sheet-like shape extending in a plane direction perpendicular to the thickness direction. The inductor 1 includes a first wiring 21, a second wiring 22, a first magnetic layer 31, a second magnetic layer 51, and a third magnetic layer 71.

[0019] The first wiring 21 and the second wiring 22 are adjacent to each other with a gap in the first direction, which is perpendicular to the electrical transmission direction (second direction) and the thickness direction. The first direction and the second direction are included in the planar direction and are perpendicular to each other in the planar direction. Of the first wiring 21 and the second wiring 22, the first wiring 21 is arranged on one side in the first direction, and the second wiring 22 is arranged on the other side in the first direction. Each of the first wiring 21 and the second wiring 22 has, for example, a substantially circular shape in cross section. Each of the first wiring 21 and the second wiring 22 has an outer circumferential surface 25 facing the first magnetic layer 31, which will be described next. Each of the first wiring 21 and the second wiring 22 includes a conductive wire 23 and an insulating film 24 covering the conductive wire 23.

[0020] Conductive wire 23 has a generally circular cross-sectional shape that shares a central axis with first wiring 21 and second wiring 22. Conductive wire 23 is made of a metal conductor such as copper. The lower limit of the radius of conductive wire 23 is, for example, 25 μm, and the upper limit is, for example, 2,000 μm.

[0021] The insulating film 24 covers the entire peripheral surface of the conductive wire 23. The insulating film 24 has a generally circular cross-sectional shape that shares a central axis with each of the first wiring 21 and the second wiring 22. Examples of materials for the insulating film 24 include insulating resins such as polyester, polyurethane, polyesterimide, polyamideimide, and polyimide. The insulating film 24 is a single layer or multiple layers. The lower limit of the thickness of the insulating film 24 is, for example, 1 μm, and the upper limit is, for example, 100 μm.

[0022] The radius of each of the first wiring 21 and the second wiring 22 is the sum of the radius of the conductor 23 and the thickness of the insulating film 24, and specifically, the lower limit is, for example, 25 μm, preferably 50 μm, and the upper limit is, for example, 2,000 μm, preferably 200 μm.

[0023] The lower limit of the distance (spacing) L0 between the first wiring 21 and the second wiring 22 is set appropriately depending on the use and purpose of the inductor 1, and is, for example, 10 μm, preferably 50 μm, and the upper limit is, for example, 10,000 μm, preferably 5,000 μm.

[0024] The first magnetic layer 31 has an inner circumferential surface 32, a first surface 33, and a second surface .

[0025] The inner peripheral surface 32 contacts the outer peripheral surfaces 25 of the first wiring 21 and the second wiring 22. As will be described next, the inner peripheral surface 32 is located between the first surface 33 and the second surface 34 in the thickness direction.

[0026] The first surface 33 is continuous in the planar direction. The first surface 33 is disposed on one side of the inner circumferential surface 32 in the thickness direction with a gap therebetween. The first surface 33 is one surface in the thickness direction of the first magnetic layer 31. The first surface 33 has a first raised portion 35, a second raised portion 36, and a one-side recess 37.

[0027] In a cross-sectional view along the thickness direction and the first direction (hereinafter, simply referred to as a "cross-sectional view"), the first protrusion 35 faces, at an interval, one thickness-direction side surface 26 of the outer peripheral surface 25 of the first wiring 21. If the first wiring 21 has a generally circular cross-sectional shape, the upper limit of the central angle α1 of the one side surface 26 of the first wiring 21 is, for example, 90 degrees, preferably 60 degrees, and the lower limit is, for example, 15 degrees, preferably 30 degrees. The central angle α1 of the one side surface 26 of the first wiring 21 is determined around the central axis CA1 of the first wiring 21. The first protrusion 35 is a region that overlaps with the one side surface 26 when projected radially from the central axis CA1 (or center of gravity) of the first wiring 21. The first protrusion 35 curves along the one side surface 26 of the first wiring 21. The curvature direction of the first protrusion 35 is the same as that of the one side surface 26 of the first wiring 21.

[0028] In a cross-sectional view, the second raised portion 36 faces, at an interval, one side surface 26 in the thickness direction of the outer peripheral surface 25 of the second wiring 22. If the second wiring 22 has a generally circular cross-sectional shape, the upper limit of the central angle α2 of the one side surface 26 of the second wiring 22 is, for example, 90 degrees, preferably 60 degrees, and the lower limit is, for example, 15 degrees, preferably 30 degrees. The central angle α2 of the one side surface 26 of the second wiring 22 is determined around the central axis CA2 of the second wiring 22. The second raised portion 36 is a region that overlaps with the one side surface 26 when projected in a radial direction from the central axis CA2 (or center of gravity) of the second wiring 22. The second raised portion 36 curves along the one side surface 26 of the second wiring 22. The curvature direction of the second raised portion 36 is the same as that of the one side surface 26 of the second wiring 22.

[0029] The one-side recess 37 is disposed between the first raised portion 35 and the second raised portion 36. The one-side recess 37 connects the first raised portion 35 and the second raised portion 36 in the first direction. When projected in the thickness direction, the one-side recess 37 does not overlap the first wiring 21 and the second wiring 22, and is disposed between the first wiring 21 and the second wiring 22. The one-side recess 37 is recessed from the first raised portion 35 and the second raised portion 36 toward the other side in the thickness direction.

[0030] The second surface 34 is disposed opposite the first surface 33 at an interval on the other side in the thickness direction. The second surface 34 is located on the opposite side of the first surface 33 with respect to the first wiring 21 and the second wiring 22. The second surface 34 is the other surface in the thickness direction of the first magnetic layer 31. The second surface 34 is continuous in the planar direction. The second surface 34 has a third raised portion 41, a fourth raised portion 42, and an other-side recess 43.

[0031] In a cross-sectional view, the third protrusion 41 faces, at an interval, the other side surface 27 in the thickness direction of the outer peripheral surface 25 of the first wiring 21. If the first wiring 21 has a generally circular shape in a cross-sectional view, the upper limit of the central angle α3 of the other side surface 27 is, for example, 90 degrees, preferably 60 degrees, and the lower limit is, for example, 15 degrees, preferably 30 degrees. The central angle α3 of the other side surface 27 is determined around the central axis CA1 of the first wiring 21. The third protrusion 41 is a region that overlaps with the other side surface 27 when projected in a radial direction from the central axis CA1 (or center of gravity) of the first wiring 21. The third protrusion 41 curves along the other side surface 27 of the first wiring 21. The curved direction of the third protrusion 41 is the same as that of the other side surface 27 of the first wiring 21.

[0032] In a cross-sectional view, the fourth protrusion 42 faces, at an interval, the other side surface 27 in the thickness direction of the outer peripheral surface 25 of the second wiring 22. If the second wiring 22 has a generally circular cross-sectional shape, the upper limit of the central angle α4 of the other side surface 27 is, for example, 90 degrees, preferably 60 degrees, and the lower limit is, for example, 15 degrees, preferably 30 degrees. The central angle α4 of the other side surface 27 is determined around the central axis CA2 of the second wiring 22. The fourth protrusion 42 is a region that overlaps with the other side surface 27 when projected in a radial direction from the central axis CA2 (or the center of gravity) of the second wiring 22. The fourth protrusion 42 curves along the other side surface 27 of the second wiring 22. The curved direction of the fourth protrusion 42 is the same as that of the other side surface 27 of the second wiring 22.

[0033] The other-side recess 43 is disposed between the third raised portion 41 and the fourth raised portion 42. The other-side recess 43 connects the third raised portion 41 and the fourth raised portion 42 in the first direction. When projected in the thickness direction, the other-side recess 43 does not overlap the first wiring 21 and the second wiring 22, and is disposed between the first wiring 21 and the second wiring 22. The other-side recess 43 is recessed from the third raised portion 41 and the fourth raised portion 42 toward one side in the thickness direction.

[0034] The material, properties and dimensions of the first magnetic layer 31 will be described later.

[0035] The second magnetic layer 51 is disposed on the first surface 33 of the first magnetic layer 31. The second magnetic layer 51 has a third surface 53 and a fourth surface .

[0036] The third surface 53 is a contact surface that contacts the first surface 33 of the first magnetic layer 31. The third surface 53 is continuous in the planar direction. The third surface 53 is the other surface of the second magnetic layer 51 in the thickness direction. The third surface 53 has a first opposing portion 55, a second opposing portion 56, and a first recess 57.

[0037] The first opposing portion 55 contacts the first raised portion 35. Specifically, the first opposing portion 55 has the same shape as the first raised portion 35 in a cross-sectional view. The first opposing portion 55 includes a first apex 91 located closest to one side in the thickness direction.

[0038] The second opposing portion 56 contacts the second raised portion 36. Specifically, the second opposing portion 56 has the same shape as the second raised portion 36 in a cross-sectional view. The second opposing portion 56 includes a second apex 92 that is located closest to one side in the thickness direction.

[0039] The first recess 57 contacts the one-side recess 37. The first recess 57 is recessed between the first opposing portion 55 and the second opposing portion 56 toward the other side in the thickness direction. Specifically, the first recess 57 has the same shape as the one-side recess 37. The first recess 57 has a first bottom 38 that is located closest to the other side in the thickness direction. The first recess 57 also includes a first arcuate surface 39 whose central axis is located on one side of the one-side recess 37 in the thickness direction. The first arcuate surface 39 includes the first bottom 38.

[0040] The fourth surface 54 is disposed opposite to and spaced apart from the third surface 53 on one side in the thickness direction. The fourth surface 54 forms one surface in the thickness direction of each of the second magnetic layer 51 and the inductor 1. The fourth surface 54 is an exposed surface that is exposed on one side in the thickness direction. The fourth surface 54 is continuous in the planar direction. The fourth surface 54 has a third opposing portion 58 , a fourth opposing portion 59 , and a second recess 60 .

[0041] The third opposing portion 58 faces the first opposing portion 55 of the third surface 53 in the thickness direction. In a cross-sectional view, the third opposing portion 58 curves along the first opposing portion 55. The third opposing portion 58 has a fifth apex 86 that faces one side in the thickness direction of the first apex 91 of the first opposing portion 55. The fifth apex 86 is located at the portion of the third opposing portion 58 closest to one side in the thickness direction.

[0042] The fourth opposing portion 59 faces the second opposing portion 56 of the third surface 53 in the thickness direction. The fourth opposing portion 59 curves along the second opposing portion 56. The fourth opposing portion 59 has a sixth apex 87 that faces one side of the second apex 92 in the thickness direction. The sixth apex 87 is located at the fourth opposing portion 59 closest to one side in the thickness direction.

[0043] The second recess 60 faces the first recess 57 of the third surface 53 in the thickness direction. The second recess 60 is recessed between the third opposing portion 58 and the fourth opposing portion 59 and from them toward the other side in the thickness direction. The second recess 60 is recessed along the first recess 57. The second recess 60 has a third bottom portion 63 that is located furthest to the other side in the thickness direction. The third bottom portion 63 faces the first bottom portion 38 of the first recess 57 in the thickness direction.

[0044] The material, properties, and dimensions of the second magnetic layer 51 will be described later.

[0045] The third magnetic layer 71 is disposed on the second surface 34 of the first magnetic layer 31. The third magnetic layer 71 has a fifth surface 73 and a sixth surface 74.

[0046] The fifth surface 73 is a contact surface that comes into contact with the second surface 34 of the first magnetic layer 31. The fifth surface 73 is continuous in the planar direction. The fifth surface 73 is one surface of the third magnetic layer 71 in the thickness direction. The fifth surface 73 has a fifth opposing portion 75, a sixth opposing portion 76, and a third recess 77.

[0047] The fifth opposing portion 75 contacts the third raised portion 41. Specifically, the fifth opposing portion 75 has the same shape as the third raised portion 41 in a cross-sectional view. The fifth opposing portion 75 has a third apex 93 that is located furthest on the other side in the thickness direction.

[0048] The sixth opposed portion 76 contacts the fourth raised portion 42. Specifically, the sixth opposed portion 76 has the same shape as the fourth raised portion 42 in a cross-sectional view. The sixth opposed portion 76 has a fourth apex 94 that is located furthest on the other side in the thickness direction.

[0049] The third recess 77 contacts the other-side recess 43. The third recess 77 is recessed between the fifth opposing portion 75 and the sixth opposing portion 76 and toward one side in the thickness direction from them. Specifically, the third recess 77 has the same shape as the other-side recess 43. The third recess 77 has a second bottom portion 44 that is located closest to one side in the thickness direction. The other-side recess 43 also includes a second arcuate surface 49 whose central axis is located on the other side in the thickness direction than the other-side recess 43. The second arcuate surface 49 includes the second bottom portion 44.

[0050] The sixth surface 74 is disposed opposite to and spaced apart from the fifth surface 73 on the other side in the thickness direction. The sixth surface 74 forms the other surface in the thickness direction of each of the third magnetic layer 71 and the inductor 1. The sixth surface 74 is an exposed surface exposed on the other side in the thickness direction. The sixth surface 74 is continuous in the planar direction. The sixth surface 74 has a seventh opposing portion 78, an eighth opposing portion 79, and a fourth recess 80.

[0051] The seventh opposing portion 78 faces the fifth opposing portion 75 of the fifth surface 73 in the thickness direction. In a cross-sectional view, the seventh opposing portion 78 curves along the fifth opposing portion 75. The seventh opposing portion 78 has a seventh apex 88 that faces the third apex 93 of the fifth opposing portion 75 on the other side in the thickness direction. The seventh apex 88 is located at the farthest point on the other side in the thickness direction of the seventh opposing portion 78.

[0052] The eighth opposing portion 79 faces the sixth opposing portion 76 of the fifth surface 73 in the thickness direction. In a cross-sectional view, the eighth opposing portion 79 curves along the sixth opposing portion 76. The eighth opposing portion 79 has an eighth apex 89 that faces the fourth apex 94 of the sixth opposing portion 76 on the other side in the thickness direction. The eighth apex 89 is located at the farthest point on the other side in the thickness direction of the eighth opposing portion 79.

[0053] The fourth recess 80 faces the third recess 77 of the fifth surface 73 in the thickness direction. The fourth recess 80 is recessed between the seventh opposing portion 78 and the eighth opposing portion 79 and recesses from them toward one side in the thickness direction. The fourth recess 80 is recessed along the third recess 77. The fourth recess 80 has a fourth bottom 64 located furthest to one side in the thickness direction. The fourth bottom 64 faces the second bottom 44 of the third recess 77 in the thickness direction.

[0054] Next, the materials, properties, and dimensions of the first magnetic layer 31, the second magnetic layer 51, and the third magnetic layer 71 will be described.

[0055] The material of the first magnetic layer 31, the second magnetic layer 51, and the third magnetic layer 71 is a magnetic composition containing magnetic particles and a resin.

[0056] Examples of the magnetic material constituting the magnetic particles include soft magnetic materials and hard magnetic materials. From the viewpoint of inductance, soft magnetic materials are preferable.

[0057] 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) with 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.

[0058] An example of a single metal body is a metal element consisting of only one type of metal element (first metal element). The first metal element is appropriately selected from metal elements that can be contained as the first metal element in a soft magnetic body, such as iron (Fe), cobalt (Co), nickel (Ni), and others.

[0059] 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 part 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.

[0060] 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.

[0061] The first metallic element is an essential element in the alloy body, and examples thereof include iron (Fe), cobalt (Co), nickel (Ni), etc. If the first metallic element is Fe, the alloy body is an Fe-based alloy, if the first metallic element is Co, the alloy body is a Co-based alloy, and if the first metallic element is Ni, the alloy body is a Ni-based alloy.

[0062] 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). Examples of rare earth elements include aluminum (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 can be used alone or in combination of two or more.

[0063] 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.

[0064] Examples of Fe-based alloys 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 such alloys include i-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 ferrites such as Mn-Mg ferrites, Mn-Zn ferrites, Ni-Zn ferrites, Ni-Zn-Cu ferrites, Cu-Zn ferrites, and Cu-Mg-Zn ferrites), permendur (Fe-Co alloys), Fe-Co-V alloys, and Fe-based amorphous alloys.

[0065] Examples of the alloy body, Co-based alloys, include Co-Ta-Zr and cobalt (Co)-based amorphous alloys.

[0066] An example of an alloy body, a Ni-based alloy, is a Ni-Cr alloy.

[0067] 2, the magnetic particles contained in the first magnetic layer 31 are substantially spherical. On the other hand, the magnetic particles contained in the second magnetic layer 51 and the third magnetic layer 71 are substantially flat (plate-shaped). Therefore, the substantially spherical magnetic particles in the first magnetic layer 31 improve the DC bias characteristics, while the substantially flat magnetic particles in the second magnetic layer 51 and the third magnetic layer 71 enable high inductance and an excellent Q value to be obtained.

[0068] The lower limit of the average maximum length of the magnetic particles is, for example, 0.1 μm, preferably 0.5 μm, and the upper limit is, for example, 200 μm, preferably 150 μm. The average maximum length of the magnetic particles is calculated as the median particle diameter of the magnetic particles.

[0069] The volume fraction (filling rate) of the magnetic particles in the magnetic composition is, for example, 10% by volume or more, and, for example, 90% by volume or less.

[0070] Examples of the resin include thermosetting resins, such as epoxy resins, melamine resins, thermosetting polyimide resins, unsaturated polyester resins, polyurethane resins, and silicone resins. From the viewpoints of adhesiveness, heat resistance, and the like, epoxy resins are preferred.

[0071] When the thermosetting resin contains an epoxy resin, it may be prepared as an epoxy resin composition containing an epoxy resin (e.g., a cresol novolac epoxy resin), a curing agent (e.g., a phenolic resin), and a curing accelerator (e.g., an imidazole compound) in appropriate proportions. The volume ratio of the thermosetting resin to 100 volume parts of the magnetic particles is, for example, 10 volume parts or more and, for example, 90 volume parts or less.

[0072] The resin may also contain a thermoplastic resin such as an acrylic resin in an appropriate proportion. The detailed formulation of the magnetic composition described above is described in, for example, JP 2014-165363 A.

[0073] The relative permeabilities of the first magnetic layer 31, the second magnetic layer 51, and the third magnetic layer 71 are all measured at a frequency of 10 MHz. The relative permeability of each of the second magnetic layer 51 and the third magnetic layer 71 is higher than the relative permeability of the first magnetic layer 31. Specifically, the lower limit of the ratio of the relative permeability of each of the second magnetic layer 51 and the third magnetic layer 71 to the relative permeability of the first magnetic layer 31 is, for example, more than 1, preferably 1.1, more preferably 1.5, and the upper limit is, for example, 20, preferably 10.

[0074] Since the relative permeability of each of the second magnetic layer 51 and the third magnetic layer 71 is higher than the relative permeability of the first magnetic layer 31, this inductor 1 has excellent DC bias characteristics.

[0075] The relative permeabilities of the first magnetic layer 31, the second magnetic layer 51, and the third magnetic layer 71 can be determined by measuring the relative permeabilities of the first sheet 65, the second sheet 66, and the third sheet 67 that form them. The relative permeabilities of the first magnetic layer 31, the second magnetic layer 51, and the third magnetic layer 71 can also be measured directly.

[0076] Next, the dimensions of the first magnetic layer 31, the second magnetic layer 51, and the third magnetic layer 71 will be described.

[0077] The length L1 between the first opposing portion 55 and the first wiring 21, the length L2 between the second opposing portion 56 and the second wiring, and the depth L3 of the first recess satisfy, for example, the following formulas (1) and (2), preferably the following formulas (1A) and (2A), more preferably the following formulas (1B) and (2B), and also, for example, the following formulas (1C) and (2C).

[0078] L3 / L1≧0.2 (1) L3 / L2≧0.2 (2)

[0079] L3 / L1≧0.3 (1A) L3 / L2≧0.3 (2A)

[0080] L3 / L1≧0.4 (1B) L3 / L2≧0.4 (2B)

[0081] L3 / L1<1.5 (1C) L3 / L2<1.5 (2C)

[0082] If L1, L2, and L3 satisfy the above formula, the depth L3 of the first recess 57 can be made sufficiently deep relative to the length L1 between the first opposing portion 55 and the first wiring 21 and the length L2 between the second opposing portion 56 and the second wiring. Therefore, as shown in FIG. 2, the substantially flat magnetic particles in the vicinity of the first recess 57 in the second magnetic layer 51 can be sufficiently oriented relative to the first recess 57. As a result, the Q value of the inductor 1 can be improved.

[0083] The lower limit of the ratio (L2 / L1) of the length L2 between the second opposing portion 56 and the second wiring to the length L1 between the first opposing portion 55 and the first wiring 21 is, for example, 0.7, preferably 0.9, and the upper limit is, for example, 1.3, preferably 1.1.

[0084] Furthermore, the length L4 between the fifth opposing portion 75 and the first wiring 21, the length L5 between the sixth opposing portion 76 and the second wiring 22, and the depth L6 of the third recess 77 satisfy, for example, the following formulas (3) and (4), preferably the following formulas (3A) and (4A), more preferably the following formulas (3B) and (4B), and also, for example, the following formulas (3C) and (4C).

[0085] L6 / L4≧0.2 (3) L6 / L5≧0.2 (4)

[0086] L6 / L4≧0.3 (3A) L6 / L5≧0.3 (4A)

[0087] L6 / L4≧0.4 (3B) L6 / L5≧0.4 (4B)

[0088] L6 / L4<1.5 (3C) L6 / L5<1.5 (4C)

[0089] If L4, L5, and L6 satisfy the above formula, the depth L6 of the third recess 77 can be made sufficiently deep relative to the length L4 between the fifth opposing portion 75 and the first wiring 21 and the length L5 between the sixth opposing portion 76 and the second wiring 22. Therefore, the substantially flat magnetic particles in the vicinity of the third recess 77 in the third magnetic layer 71 can be sufficiently oriented relative to the third recess 77. As a result, the Q value of the inductor 1 can be improved.

[0090] Furthermore, with regard to L1 to L6, for example, formulas (1), (2), (3), and (4) are simultaneously satisfied, preferably formulas (1A), (2A), (3A), and (4A) are simultaneously satisfied, more preferably formulas (1B), (2B), (3B), and (4B) are simultaneously satisfied, and even more preferably formulas (1C), (2C), (3C), and (4C) are simultaneously satisfied. This allows the Q value of the inductor 1 to be efficiently improved.

[0091] Furthermore, the lower limit of the ratio (L5 / L4) of the length L5 between the sixth opposing portion 76 and the second wiring 22 to the length L4 between the fifth opposing portion 75 and the first wiring 21 is, for example, 0.7, preferably 0.9, and the upper limit is, for example, 1.3, preferably 1.1.

[0092] Furthermore, for example, the depth L3 of the first recess 57 and the depth L7 of the second recess 60 satisfy, for example, the following formula (5), preferably satisfy the following formula (5A), more preferably satisfy the following formula (5B), and also, for example, satisfy the following formula (5C).

[0093] L7 / L3≧0.3 (5)

[0094] L7 / L3≧0.5 (5A)

[0095] L7 / L3≧0.7 (5B)

[0096] L7 / L3<1.0 (5C)

[0097] If L3 and L7 satisfy the above formula, the depth L7 of the second recess 60 can be made sufficiently deeper than the depth L3 of the first recess 57. Therefore, as shown in Fig. 2, the substantially flat magnetic particles between the first recess 57 and the second recess 60 can be sufficiently oriented along the first recess 57 and the deeply recessed second recess 60. As a result, the Q value of the inductor 1 can be improved.

[0098] The depth L6 of the third recess 77 and the depth L8 of the fourth recess 80 satisfy, for example, the following formula (6), preferably satisfy the following formula (6A), more preferably satisfy the following formula (6B), and also, for example, satisfy the following formula (6C).

[0099] L8 / L6≧0.3 (6)

[0100] L8 / L6≧0.5 (6A)

[0101] L8 / L6≧0.7 (6B)

[0102] L8 / L6<1.0 (6C)

[0103] If L6 and L8 satisfy the above formula, the depth L8 of the fourth recess 80 can be made sufficiently deeper than the depth L6 of the third recess 77. Therefore, as shown in Fig. 2, the substantially flat magnetic particles between the third recess 77 and the fourth recess 80 can be sufficiently oriented along the third recess 77 and the deeply recessed fourth recess 80. As a result, the Q value of the inductor 1 can be improved.

[0104] Furthermore, with respect to the depths L3 and L6 to L8, for example, the formula (5) and the formula (6) are satisfied simultaneously, preferably the formula (5A) and the formula (6A) are satisfied simultaneously, more preferably the formula (5B) and the formula (6B) are satisfied simultaneously, and further preferably the formula (5C) and the formula (6C) are satisfied simultaneously. This allows the Q value of the inductor 1 to be efficiently improved.

[0105] Furthermore, for example, the length L1 between the first opposing portion 55 and the first wiring 21 and the thickness direction length L9 of the first wiring 21 satisfy, for example, the following formula (7), preferably the following formula (7A), more preferably the following formula (7B), and also, for example, the following formula (7C).

[0106] L1 / L9≧0.1 (7)

[0107] L1 / L9≧0.2 (7A)

[0108] L1 / L9≧0.25 (7B)

[0109] L1 / L9<1.0 (7C)

[0110] If L1 and L9 satisfy the above formula, the length L1 between the first opposing portion 55 and the first wiring 21 can be made sufficiently longer with respect to the thickness direction length L9 of the first wiring 21. Therefore, the Q value of the inductor 1 can be improved while maintaining a high inductance of the inductor 1.

[0111] The length L2 between the second opposing portion 56 and the second wiring 22 and the thickness direction length L10 of the second wiring 22 satisfy, for example, the following formula (8), preferably the following formula (8A), more preferably the following formula (8B), and also, for example, the following formula (8C).

[0112] L2 / L10≧0.1 (8)

[0113] L2 / L10≧0.2 (8A)

[0114] L2 / L10≧0.25 (8B)

[0115] L2 / L10<1.0 (8C)

[0116] If L2 and L10 satisfy the above formula, the length L2 between the two opposing portions 56 and the second wiring 22 can be made sufficiently longer than the thickness direction length L10 of the second wiring 22. Therefore, the Q value of the inductor 1 can be improved while maintaining a high inductance of the inductor 1.

[0117] The length L4 between the third opposing portion 58 and the first wiring 21, and the length L9 of the first wiring 21, for example, satisfy the following formula (9), preferably satisfy the following formula (9A), more preferably satisfy the following formula (9B), and also, for example, satisfy the following formula (9C).

[0118] L4 / L9≧0.1 (9)

[0119] L4 / L9≧0.2 (9A)

[0120] L4 / L9≧0.25 (9B)

[0121] L4 / L9<1.0 (9C)

[0122] If L4 and L9 satisfy the above formula, the length L4 between the third opposing portion 58 and the first wiring 21 can be made sufficiently longer than the length L9 of the first wiring 21. Therefore, the Q value of the inductor 1 can be improved while maintaining a high inductance of the inductor 1.

[0123] The length L5 between the fourth opposing portion 59 and the second wiring 22, and the length L10 of the second wiring 22, satisfy the following formula (10), preferably satisfy the following formula (10A), more preferably satisfy the following formula (10B), and also, for example, satisfy the following formula (10C).

[0124] L5 / L10≧0.1 (10)

[0125] L5 / L10≧0.2 (10A)

[0126] L5 / L10≧0.25 (10B)

[0127] L5 / L10<1.0 (10C)

[0128] If L5 and L10 satisfy the above formula, the length L5 between the fourth opposing portion 59 and the second wiring 22 can be made sufficiently longer than the length L10 of the second wiring 22. Therefore, the Q value of the inductor 1 can be improved while maintaining a high inductance of the inductor 1.

[0129] Furthermore, with regard to the above-mentioned L1, L2, L4, L5, L9, and L10, for example, equations (7), (8), (9), and (10) are simultaneously satisfied, preferably equations (7A), (8A), (9A), and (10A) are simultaneously satisfied, more preferably equations (7B), (8B), (9B), and (10B) are simultaneously satisfied, and even more preferably equations (7C), (8C), (9C), and (10C) are simultaneously satisfied. This allows the Q value of the inductor 1 to be efficiently improved.

[0130] The lengths L1 to L10 are defined as follows.

[0131] The length L1 between the first opposing portion 55 and the first wiring 21 is the shortest distance L1 between the first top portion 91 and the first wiring 21.

[0132] The length L2 between the second opposing portion 56 and the second wiring 22 is the shortest distance between the second apex 92 and the second wiring 22.

[0133] The depth L3 of the first recess 57 is the longest length L3 in the thickness direction from the line segment connecting the first top 91 and the second top 92 to the first bottom 38 of the first recess 57.

[0134] The length L4 between the fifth opposing portion 75 and the first wiring 21 is the shortest distance L4 between the third apex 93 and the first wiring 21.

[0135] The length L5 between the sixth opposing portion 76 and the second wiring 22 is the shortest distance L5 between the fourth apex 94 and the second wiring 22.

[0136] The depth L6 of the second recess 60 is the longest length L6 in the thickness direction from the line segment connecting the third apex 93 and the fourth apex 94 to the second bottom 44 of the third recess 77.

[0137] The depth L7 of the second recess 60 is the longest length L7 in the thickness direction from the line segment connecting the fifth apex 86 and the sixth apex 87 to the third bottom 63 of the second recess 60.

[0138] The depth L8 of the fourth recess 80 is the longest length L8 in the thickness direction from the line segment connecting the seventh apex 88 and the eighth apex 89 to the fourth bottom 64 of the fourth recess 80.

[0139] The lower limit of the Q value of this inductor 1 is, for example, 30, preferably 35, and more preferably 40. If the Q value is equal to or greater than the above-mentioned lower limit, the resistance component that becomes loss is small, and therefore the inductance is high. On the other hand, there is no particular upper limit to the Q value of the inductor 1, and a high Q value is preferable.

[0140] Next, an example of a method for manufacturing the inductor 1 will be described.

[0141] The manufacturing method of this inductor 1 includes a first step (see Figure 3) of preparing a heat press device 2, and a second step (see Figure 7) of heat pressing a magnetic sheet 8 (described later) and first wiring 21 and second wiring 22 using the heat press device 2.

[0142] [1st step] As shown in FIG. 3, in the first step, a heat press device 2 is prepared.

[0143] The heat press device 2 is an isotropic press device that can isotropically heat press (isotropically press) the magnetic sheet 8, the first wiring 21, and the second wiring 22 (see FIG. 4). The heat press device 2 includes a first die 3, a second die 4, an inner frame member 5, an outer frame member 81, and a fluid flexible sheet 6.

[0144] In this embodiment, the heat press device 2 is configured so that the second die 4, inner frame member 5, and outer frame member 81 can approach and press (closely contact) the first die 3. The first die 3 is immobile in the pressing direction of the heat press device 2.

[0145] The first die 3 has a generally plate-like shape. The first die 3 has a first press surface 61 that faces the second die 4, which will be described next. The first press surface 61 extends in a direction (plane direction) perpendicular to the pressing direction. The first press surface 61 is flat. Furthermore, the first die 3 includes a heater (not shown).

[0146] In the first step, the second die 4 is spaced apart from the first die 3 in the pressing direction. The second die 4 is movable in the pressing direction relative to the first die 3. The second die 4 has a generally plate-like shape that is smaller than the first die 3. Specifically, the second die 4 is contained within the first die 3 when projected in the pressing direction. More specifically, the second die 4 overlaps with the center of the first die 3 in the planar direction when projected in the pressing direction. The second die 4 has a second pressing surface 62 that faces the center of the first pressing surface 61 of the first die 3 in the planar direction. The second pressing surface 62 extends in the planar direction. The second pressing surface 62 is parallel to the first pressing surface 61. The second die 4 also includes a heater (not shown).

[0147] The inner frame member 5 surrounds the second die 4. Although not shown in detail, the inner frame member 5 surrounds the entire periphery of the second die 4. Furthermore, in the first step, the inner frame member 5 is spaced apart from the peripheral edge of the first die 3 in the pressing direction. That is, in the first step, the inner frame member 5 is disposed opposite the peripheral edge of the first die 3 at a distance in the pressing direction. The inner frame member 5 integrally has a third press surface 98 that faces the peripheral edge of the first press surface 61, and an inner side surface 99 that faces inward. The inner frame member 5 is movable in the pressing direction relative to both the first die 3 and the second die 4.

[0148] A sealing member (not shown) is provided between the inner frame member 5 and the second mold 4. The sealing member (not shown) prevents the flowable flexible sheet 6 (described below) from entering between the inner frame member 5 and the second mold 4 during relative movement between the inner frame member 5 and the second mold 4.

[0149] The outer frame member 81 surrounds the inner frame member 5. Although not shown in detail, the outer frame member 81 surrounds the entire periphery of the inner frame member 5. Furthermore, in the first step, the outer frame member 81 is spaced apart in the pressing direction from the peripheral edge of the first die 3. That is, in the first step, the outer frame member 81 is disposed opposite the peripheral edge of the first die 3 at a distance in the pressing direction. The outer frame member 81 integrally has a contact surface 82 that faces the peripheral edge of the first press surface 61, and a chamber inner side surface 83 that faces inward. The outer frame member 81 is movable in the pressing direction relative to both the first die 3 and the inner frame member 5.

[0150] The outer frame member 81 also has an exhaust port 15. The exhaust port 15 has an upstream end in the exhaust direction facing the inner end of the chamber inner side surface 83. The exhaust port 15 is connected to a vacuum pump 16 via an exhaust line 46. Note that in the first step, the exhaust line 46 is closed.

[0151] In addition, a sealing member (not shown) is provided between the outer frame member 81 and the inner frame member 5. The sealing member (not shown) prevents the second sealed space (described below) 45 from communicating with the outside during relative movement between the outer frame member 81 and the inner frame member 5.

[0152] The fluid flexible sheet 6 has a generally plate-like shape extending in a planar direction perpendicular to the pressing direction. The fluid flexible sheet 6 is arranged on the second pressing surface 62 of the second die 4. The fluid flexible sheet 6 is also arranged on the inner surface 99 of the inner frame member 5. More specifically, the fluid flexible sheet 6 is in contact with the entire surface of the second pressing surface 62 and a downstream portion of the inner surface 99 in the pressing direction. A sealing member (not shown) is provided between the fluid flexible sheet 6 and the inner surface 99 of the inner frame member 5. The inner frame member 5 is movable in the pressing direction relative to the fluid flexible sheet 6.

[0153] The material of the flowable flexible sheet 6 is not particularly limited as long as it is a material that can exhibit flowability and flexibility during heat pressing, and examples thereof include gel or soft elastomer. The material of the flowable flexible sheet 6 may be a commercially available product, and examples thereof include the αGEL series (manufactured by Taica Corporation) and the RIKEN ELASTOMER series (manufactured by RIKEN TECHNOS CORPORATION). The thickness of the flowable flexible sheet 6 is not particularly limited, and specifically, the lower limit of the thickness is, for example, 1 mm, preferably 2 mm, and the upper limit of the thickness is, for example, 1,000 mm, preferably 100 mm.

[0154] The heat press device 2 is described in detail in, for example, Japanese Patent Application Laid-Open No. 2004-296746, etc. Also, a commercially available product can be used as the heat press device 2, for example, the Dry Laminator series manufactured by Nikkiso Co., Ltd., etc.

[0155] [Second process] In the second step, the magnetic sheet 8, the first wiring 21, and the second wiring 22 are heat-pressed by the heat press device 2, as shown in Fig. 7. Specifically, the second step includes a third step, a fourth step, a fifth step, and a sixth step. In the second step, the third step, the fourth step, the fifth step, and the sixth step are carried out in this order.

[0156] [3rd step] As shown in FIG. 4, in the third step, first, the first release sheet 14 is placed on the first pressing surface 61 of the first die 3 .

[0157] The first release sheet 14 is smaller than the inner frame member 5 when projected in the thickness direction.

[0158] The first release sheet 14 includes, for example, a first release film 11, a cushion film 12, and a second release film 13, arranged in this order downstream in the pressing direction. The materials for the first release film 11 and the second release film 13 are appropriately selected depending on the application and purpose, and examples include polyesters such as polyethylene terephthalate (PET), and polyolefins such as polymethylpentene (TPX) and polypropylene. The thickness of the first release film 11 and the second release film 13 is, for example, 1 μm or more and, for example, 1,000 μm or less. The cushion film 12 includes a flexible layer. The flexible layer flows in the planar and thickness directions during the heat pressing in the second step. Examples of materials for the flexible layer include a thermo-fluid material that flows in the planar and press directions during the heat pressing in the second step described below. The thermo-fluid material mainly contains, for example, an olefin-(meth)acrylate copolymer (e.g., ethylene-methyl(meth)acrylate copolymer), an olefin-vinyl acetate copolymer, or the like. The thickness of the cushion film 12 is, for example, 50 μm or more and, for example, 500 μm or less. The cushion film 12 may be a commercially available product, such as the release film OT series (manufactured by Sekisui Chemical Co., Ltd.).

[0159] The first release sheet 14 can include the cushion film 12 and either the first release film 11 or the second release film 13, or it may be the cushion film 12 only.

[0160] After the first release sheet 14 is placed on the first mold 3, the magnetic sheet 8 and the first wiring 21 and second wiring 22 are set between the first release sheet 14 and the second release sheet 7 so as to overlap with the fluid flexible sheet 6 when projected in the pressing direction.

[0161] The magnetic sheet 8 includes three types of magnetic sheets for forming the first magnetic layer 31, the second magnetic layer 51, and the third magnetic layer 71. Specifically, the magnetic sheet 8 includes a first sheet 65, a second sheet 66, and a third sheet 67. The first sheet 65 is a magnetic sheet for forming the first magnetic layer 31. The second sheet 66 is a magnetic sheet for forming the second magnetic layer 51. The third sheet 67 is a magnetic sheet for forming the third magnetic layer 71. Each of the first sheet 65, the second sheet 66, and the third sheet 67 may be singular or plural. The magnetic sheet 8 is made of the magnetic composition described above. Note that the thermosetting resin in the magnetic composition that forms the magnetic sheet 8 is in a B-stage.

[0162] Specifically, when there are multiple first sheets 65, a third sheet 67, one first sheet 65, the first wiring 21 and the second wiring 22, another first sheet 65, and the second sheet 66 are laminated in this order in the pressing direction. At this time, the magnetic sheet 8 is temporarily fixed to the first wiring 21 and the second wiring 22 using a plate press equipped with two parallel plates, and the laminate 48 can be produced.

[0163] Thereafter, the second release sheet 7 is placed on the laminate 48 (third sheet 67).

[0164] The second release sheet 7 has the same layer structure as the first release sheet 14. For example, the first release sheet 14 is smaller than the inner frame member 5 when projected in the thickness direction.

[0165] [4th step] In the fourth step, as shown by the arrow in FIG. 4 and as shown in FIG. 5, the outer frame member 81 is brought into contact with the first mold 3 to form a reduced pressure space 85.

[0166] Specifically, the outer frame member 81 is pressed against the peripheral edge of the first press surface 61 of the first die 3. This causes the contact surface 82 of the outer frame member 81 and the peripheral edge of the first press surface 61 of the first die 3 to come into close contact (adhesion) (preferably press) with each other.

[0167] The reduced pressure space 85 is partitioned by the chamber inner side surface 83 of the outer frame member 81, the third press surface 98 and the inner side surface 99 of the inner frame member 5, the second press surface 62 of the flowable flexible sheet 6, and the first press surface 61 of the first die 3. The chamber inner side surface 83 that partitions the reduced pressure space 85, together with the first die 3, constitutes a chamber device.

[0168] The pressure of the outer frame member 81 against the first die 3 is set to a level that ensures airtightness (tightness to the outside) of the reduced pressure space 85 described later by the close contact of the contact surface 82 and the first press surface 61, specifically, 0.1 MPa or more and 20 MPa or less.

[0169] As a result, a first sealed space 84 is formed between the first mold 3, the outer frame member 81, and the flowable flexible sheet 6. The first sealed space 84 is shielded from the outside. However, the exhaust line 46 communicates with the first sealed space 84.

[0170] On the other hand, the second release sheet 7 and the flowable flexible sheet 6 are still spaced apart in the pressing direction.

[0171] Subsequently, in a fourth step, the first sealed space 84 is depressurized to form a depressurized space 85.

[0172] Specifically, the vacuum pump 16 is driven, and then the exhaust line 46 is opened. This reduces the pressure in the first sealed space 84 that communicates with the exhaust port 15. As a result, the first sealed space 84 becomes a reduced-pressure space 85.

[0173] The upper limit of the pressure in the reduced pressure space 85 (or the exhaust line 46) is, for example, 100,000 Pa, preferably 10,000 Pa, and the lower limit is 1 Pa.

[0174] [5th ​​step] In a fifth step, as shown by the arrows in FIG. 5 and in FIG. 6, the inner frame member 5 is pressed against the first die 3 to form the second sealed space 45.

[0175] Specifically, the inner frame member 5 is pressed against the peripheral edge of the first press surface 61 of the first die 3 via the second release sheet 7. This causes the third press surface 98 of the inner frame member 5 and the peripheral edge of the first press surface 61 of the first die 3 to come into close contact with each other.

[0176] The pressure of the inner frame member 5 against the first mold 3 is set to a level that prevents leakage of the fluid flexible sheet 6 described later to the outside by the close contact between the third press surface 98 and the first press surface 61, specifically, 0.1 MPa or more and 50 MPa or less.

[0177] As a result, a second sealed space 45 is formed inside the inner frame member 5, surrounded in the pressing direction by the first mold 3 and the flowable flexible sheet 6. The inner frame member 5 blocks communication between the second sealed space 45 and the exhaust line 46.

[0178] The second sealed space 45 has the same degree of decompression (air pressure) as the decompression space 85 described above.

[0179] The second release sheet 7 and the flowable flexible sheet 6 are still spaced apart in the pressing direction.

[0180] [6th step] As shown by the arrows in Figure 6 and Figure 7, in the sixth step, the second mold 4 is brought close to the first mold 3, and the magnetic sheet 8, the first wiring 21, and the second wiring 22 are heat-pressed via the fluid flexible sheet 6, the second release sheet 7, and the first release sheet 14.

[0181] First, the heaters included in the first die 3 and the second die 4 are heated. Then, the second die 4 is moved in the pressing direction. Then, the flowable flexible sheet 6 approaches the second release sheet 7 as the second die 4 moves.

[0182] As a result, the flowable flexible sheet 6 flexibly contacts the entire surface, except for the peripheral edge, of the upstream side in the pressing direction of the second release sheet 7. At this time, since the flowable flexible sheet 6 has flowability and flexibility, it adheres closely to the second release sheet 7 along the shapes of the first wiring 21 and the second wiring 22.

[0183] Furthermore, the second die 4 is heat-pressed toward the first die 3 .

[0184] The lower limit of the heat press pressure is, for example, 0.1 MPa, preferably 1 MPa, more preferably 2 MPa, and the upper limit is, for example, 30 MPa, preferably 20 MPa, more preferably 10 MPa. The lower limit of the heating temperature is, for example, 100°C, preferably 110°C, more preferably 130°C, and the upper limit is, for example, 200°C, preferably 185°C, more preferably 175°C. The lower limit of the heating time is, for example, 1 minute, preferably 5 minutes, more preferably 10 minutes, and the upper limit is, for example, 1 hour, preferably 30 minutes.

[0185] As a result, the magnetic sheet 8 and the first wiring 21 and second wiring 22 are pressed with equal pressure from both sides in the thickness direction and the surface direction of the magnetic sheet 8. In other words, the magnetic sheet 8 and the first wiring 21 and second wiring 22 are isotropically pressed.

[0186] Then, the magnetic sheet 8 flows so as to bury the first wirings 21 and the second wirings 22. The magnetic sheet 8 also straddles between the adjacent first wirings 21 and second wirings 22.

[0187] Additionally, the peripheral side surface 52 of the magnetic sheet 8 is pressed inward from the side (outside) by the flowable flexible sheet 6 and the second release sheet 7. This prevents the peripheral side surface 52 of the magnetic sheet 8 from flowing outward.

[0188] The flow of the magnetic sheet 8 described above is caused by the flow of the B-stage thermosetting resin due to heating by the heaters of the first die 3 and the second die 4, and the flow of the thermoplastic resin that is blended in as needed.

[0189] Further heating by the heater causes the thermosetting resin to enter the C-stage state, which means that the first magnetic layer 31, the second magnetic layer 51, and the third magnetic layer 71 are formed, each containing magnetic particles and a cured body (C-stage body) of the thermosetting resin.

[0190] This results in the production of an inductor 1 comprising a first wiring 21 and a second wiring 22, a first magnetic layer 31 covering the first wiring 21 and the second wiring 22 so as to straddle the space between adjacent first wirings 21 and second wirings 22, and a second magnetic layer 51 and a third magnetic layer 71 arranged on the first surface 33 and the second surface 34 of the first magnetic layer 31, respectively.

[0191] As shown in FIG. 8 , the inductor 1 is then removed from the heat press device 2. The inductor 1 is then subjected to contour processing. For example, through holes 47 are formed in the second magnetic layer 51 and the first magnetic layer 31 corresponding to the longitudinal ends of the first wiring 21 and the second wiring 22. Specifically, the through holes 47 are formed by removing the corresponding second magnetic layer 51, first magnetic layer 31, and insulating film 24 using a laser, a drilling machine, or the like. The through holes 47 expose a portion of one side surface 26 of the conductive wire 23.

[0192] Thereafter, a conductive member (not shown) is placed in the through hole 47, and an external device is electrically connected to the conductor 23 via a conductive connecting material such as solder, solder paste, or silver paste. The conductive member includes plating.

[0193] Thereafter, if necessary, the conductive member and the conductive connecting material are reflowed in a reflow step.

[0194] [Effects of one embodiment] This inductor 1 includes a first magnetic layer 31 containing substantially spherical magnetic particles, and a second magnetic layer 51 and a third magnetic layer 71 containing substantially flat magnetic particles. Moreover, the relative permeability of each of the second magnetic layer 51 and the third magnetic layer 71 is higher than the relative permeability of the first magnetic layer 31. Therefore, this inductor 1 has high inductance and excellent DC bias characteristics.

[0195] Furthermore, because the second magnetic layer 51 has the first recesses 57 and the second recesses 60, in the region of the second magnetic layer 51 surrounded by the first recesses 57 and the second recesses 60, the magnetic particles having a substantially flat shape can be efficiently oriented in the first recesses 57 and the second recesses 60. Furthermore, because the third magnetic layer 71 has the third recesses 77 and the fourth recesses 80, in the region of the third magnetic layer 71 surrounded by the third recesses 77 and the fourth recesses 80, the magnetic particles having a substantially flat shape can be efficiently oriented in the third recesses 77 and the fourth recesses 80. Therefore, an excellent Q value can be obtained.

[0196] Therefore, this inductor has a high inductance, excellent DC bias characteristics, and an excellent Q value.

[0197] Furthermore, if L1, L2, and L3 satisfy formulas (1) and (2), the depth L3 of the first recess 57 can be made sufficiently deep relative to the length L1 between the first opposing portion 55 and the first wiring 21 and the length L2 between the second opposing portion 56 and the second wiring. Therefore, as shown in FIG. 2, the substantially flat magnetic particles in the vicinity of the first recess 57 in the second magnetic layer 51 can be sufficiently oriented relative to the first recess 57. As a result, the Q value of the inductor 1 can be improved. L3 / L1≧0.2 (1) L3 / L2≧0.2 (2)

[0198] Furthermore, if L4, L5, and L6 satisfy the formulas (3) and (3), the depth L6 of the third recess 77 can be made sufficiently deep relative to the length L4 between the fifth opposing portion 75 and the first wiring 21 and the length L5 between the sixth opposing portion 76 and the second wiring 22. Therefore, the substantially flat magnetic particles in the vicinity of the third recess 77 in the third magnetic layer 71 can be sufficiently oriented relative to the third recess 77. As a result, the Q value of the inductor 1 can be improved. L6 / L4≧0.2 (3) L6 / L5≧0.2 (4)

[0199] If L3 and L7 satisfy formula (5), the depth L7 of the second recess 60 can be made sufficiently deeper than the depth L3 of the first recess 57. Therefore, as shown in Fig. 2, the substantially flat magnetic particles between the first recess 57 and the second recess 60 can be sufficiently oriented along the first recess 57 and the deeply recessed second recess 60. As a result, the Q value of the inductor 1 can be improved. L7 / L3≧0.3 (5)

[0200] If L6 and L8 satisfy formula (6), the depth L8 of the fourth recess 80 can be made sufficiently deeper than the depth L6 of the third recess 77. Therefore, as shown in Fig. 2, the substantially flat magnetic particles between the third recess 77 and the fourth recess 80 can be sufficiently oriented along the third recess 77 and the deeply recessed fourth recess 80. As a result, the Q value of the inductor 1 can be improved. L8 / L6≧0.3 (6)

[0201] If L1 and L9 satisfy the formula (7), the length L1 between the first opposing portion 55 and the first wiring 21 can be made sufficiently long with respect to the thickness direction length L9 of the first wiring 21. Therefore, the Q value of the inductor 1 can be improved while maintaining a high inductance of the inductor 1. L1 / L9≧0.1 (7)

[0202] If L2 and L10 satisfy the formula (8), the length L2 between the second opposing portion 56 and the second wiring 22 can be made sufficiently longer with respect to the thickness direction length L10 of the second wiring 22. Therefore, the Q value of the inductor 1 can be improved while maintaining a high inductance of the inductor 1. L2 / L10≧0.1 (8)

[0203] If L4 and L9 satisfy the formula (9), the length L4 between the third opposing portion 58 and the first wiring 21 can be made sufficiently longer than the length L9 of the first wiring 21. Therefore, the Q value of the inductor 1 can be improved while maintaining a high inductance of the inductor 1. L4 / L9≧0.1 (9)

[0204] If L5 and L10 satisfy the above formula, the length L5 between the fourth opposing portion 59 and the second wiring 22 can be made sufficiently longer than the length L10 of the second wiring 22. Therefore, the Q value of the inductor 1 can be improved while maintaining a high inductance of the inductor 1. L5 / L10≧0.1 (10)

[0205] <Modification of one embodiment> In the following modifications, the same components and steps as those in the above-described embodiment are denoted by the same reference numerals, and detailed descriptions thereof will be omitted. Furthermore, the modifications can achieve the same effects as those in the above-described embodiment, unless otherwise specified. Furthermore, the embodiment and its modifications can be combined as appropriate.

[0206] In one embodiment, multiple magnetic sheets 8 are heat-pressed together, but although not shown, for example, the first sheet 65, the second sheet 66, and the third sheet 67 can also be heat-pressed in sequence.

[0207] Furthermore, this inductor 1 was manufactured using the heat press device 2 shown in Figure 3, but the manufacturing device is not particularly limited as long as it can form the second recess 60 in the second magnetic layer 51 and the fourth recess 80 in the third magnetic layer 71.

[0208] However, flat plate pressing is not suitable for this embodiment because it is not possible to form the second recess 60 and the fourth recess 80 described above, and the fourth surface 54 and the sixth surface 74 become flat.

[0209] 9, the inductor 1 can further include a functional layer 95 that does not contain magnetic particles. The functional layer 95 includes a first functional layer 96 disposed on the fourth surface 54 of the second magnetic layer 51 and a second functional layer 97 disposed on the sixth surface 74 of the third magnetic layer 71. The first functional layer 96 and the second functional layer 97 are, for example, both resin layers made only of resin.

[0210] One thickness direction surface of the first functional layer 96 and the other thickness direction surface of the second functional layer 97 are both flat surfaces. One thickness direction surface of the first functional layer 96 and / or the other thickness direction surface of the second functional layer 97 are provided as, for example, a pickup surface of an adsorption (suction) type pickup device.

[0211] The functional layer 95 may also be a barrier layer that suppresses the permeation of water and / or oxygen, thereby preventing the second magnetic layer 51 and the third magnetic layer 71 from being corroded by the barrier layer.

[0212] Although not shown, each of the first wiring 21 and the second wiring 22 may have a generally polygonal cross-sectional shape such as a generally rectangular cross-sectional shape. [Example]

[0213] The present invention will be described in more detail below with reference to preparation examples, examples, and comparative examples. It should be noted that the present invention is not limited to the preparation examples, examples, and comparative examples. The specific numerical values ​​of the blending ratios (content ratios), physical property values, parameters, etc. used in the following description can be replaced with the upper limit (a numerical value defined as "equal to or less than") or lower limit (a numerical value defined as "equal to or more than" or "exceeding") of the corresponding blending ratios (content ratios), physical property values, parameters, etc. described in the "Description of the Invention" above.

[0214] Preparation Example 1 (Preparation of binder) A binder was prepared by mixing 24.5 parts by mass of epoxy resin (main component), 24.5 parts by mass of phenol resin (curing agent), 1 part by mass of imidazole compound (curing accelerator), and 50 parts by mass of acrylic resin (thermoplastic resin).

[0215] Example 1 As shown in FIG. 3, first, a dry laminator (manufactured by Nikkiso Co., Ltd.) was prepared as the above-mentioned heat press device 2 (implementation of the first step).

[0216] In addition, the magnetic particles and the binder of Preparation Example 1 were compounded and mixed to obtain the volume ratios shown in Table 1 to produce the first sheet 65, the second sheet 66 and the third sheet 67 (magnetic sheet 8), each with the type and volume ratio of magnetic particles shown in Table 1.

[0217] The first wiring 21 having an L9 of 260 μm and the second wiring 22 having an L10 of 260 μm were sandwiched between the above-mentioned magnetic sheets 8, and a laminate 48 was produced by plate pressing. The distance L0 between the first wiring 21 and the second wiring 22 was 240 μm. The plate pressing conditions were a temperature of 110°C, 1 minute, and a pressure of 0.9 MPa (2 kN gauge pressure).

[0218] 5, the outer frame member 81 was brought into close contact with the first mold 3 to form a first sealed space 84. Subsequently, the vacuum pump 16 was driven to reduce the pressure in the first sealed space 84, thereby forming a reduced pressure space 85 (fourth step). The air pressure in the reduced pressure space 85 was 2666 Pa (20 torr).

[0219] Thereafter, as shown in FIG. 6, the inner frame member 5 was pressed into the first die 3 to form a second sealed space 45 smaller than the reduced pressure space 85 and having a pressure of 2666 Pa (fifth step).

[0220] Thereafter, as shown in Fig. 7, the second mold 4 was brought close to the first mold 3, and the magnetic sheet 8, the first wiring 21, and the second wiring 22 were heat-pressed via the flowable flexible sheet 6, the second release sheet 7, and the first release sheet 14 (sixth step). The heat-pressing temperature was 170°C, and the heat-pressing time was 15 minutes. The heat-pressing pressure was as shown in Table 1.

[0221] In this way, the inductor 1 including the first wiring 21, the second wiring 22, the first magnetic layer 31, the second magnetic layer 51, and the third magnetic layer 71 was manufactured.

[0222] Example 2 Inductor 1 was fabricated in the same manner as in Example 1, except that the thicknesses of first sheet 65, second sheet 66, and third sheet 67 were changed as shown in Table 2.

[0223] Comparative Example 1 As shown in Table 3, the inductor 1 was produced in the same manner as in Example 1, except that the first sheet 65, the second sheet 66 and the third sheet 67 were heat-pressed using a flat press device instead of the heat press device 2 shown in Figures 3 to 7.

[0224] evaluation (Cross-section observation and dimensions) The dimensions of each member of the inductor 1 in each example in a cross-sectional view were determined by SEM cross-sectional observation. The results are shown in Table 4.

[0225] Additionally, the shapes of the second magnetic layer 51 and the third magnetic layer 71 were observed. In Examples 1 and 2, the second magnetic layer 51 had the second recesses 60. The third magnetic layer 71 had the fourth recesses 80.

[0226] The shape of the inductor 1 of Comparative Example 1 was observed. In the inductor 1 of Comparative Example 1, the second magnetic layer 51 did not have the second recess 60, and the fourth surface 54 was flat. In the inductor 1 of Comparative Example 1, the third magnetic layer 71 did not have the fourth recess 80, and the sixth surface 74 was flat.

[0227] <Inductance> The inductances of the first wiring 21 and the second wiring 22 of the inductor 1 in each embodiment were measured. The inductance at a frequency of 10 MHz was evaluated according to the following criteria. In the measurement, an impedance analyzer (manufactured by Agilent, "4291B") was used.

[0228] [Criteria] ○: The inductance was 250 nH or more.

[0229] [DC Superposition Characteristics] The inductance reduction rate of the inductor 1 at a frequency of 10 MHz in each embodiment was measured to evaluate the DC superposition characteristics. In the measurement of the inductance reduction rate, an impedance analyzer (manufactured by Kuwaki Electronics, "65120B") was used. The inductance reduction rate was evaluated according to the following criteria. [Inductance without applying DC bias current - Inductance with DC bias current of 10 A applied] / [Inductance with DC bias current of 10 A applied] × 100 (%)

[0230] [Criteria] ○: The inductance reduction rate with respect to Comparative Example 1 was 30% or less.

[0231] [Q value] The Q value of the inductor 1 in each embodiment was measured. The Q value was evaluated according to the following criteria. In the measurement, an impedance analyzer (manufactured by Agilent, "4291B") was used.

[0232] [Criteria] ○: The Q value was 30 or more. ×: The Q value was less than 30.

[0233] [Table 1]

[0234] [Table 2]

[0235] [Table 3]

[0236] [Table 4]

[0237] [Table 5] [Explanation of symbols]

[0238] 1 inductor 21 1st wiring 22 2nd wiring 25 Outer surface 31 1st magnetic layer 32 Inner surface 33 Page 1 34 2nd page 51 Second magnetic layer 53 Page 3 54 Page 4 55 First opposing part 56 Second opposing part 57 First recess 58 Third opposing part 59 Fourth opposing part 60 Second recess 71 Third magnetic layer 73 Page 5 74 Page 6 75 5th opposing part 76 6th opposing part 77 Third recess 78 7th opposing part 79 8th opposing part 80 4th recess L1: Length between the first opposing part and the first wiring L2: Length between the second opposing part and the second wiring L3 Depth of the first recess L4 Length between the fifth opposing part and the first wiring L5 Length between the sixth opposing part and the second wiring L6 Depth of the third recess L7 Depth of the second recess L8 Depth of the 4th recess L9 Length of the first wire L10 Length of the second wire

Claims

1. a first wiring and a second wiring adjacent to each other with a gap therebetween; a first magnetic layer having a first surface continuous in a surface direction, a second surface spaced apart from the first surface in a thickness direction and continuous in the surface direction, and an inner circumferential surface located between the first surface and the second surface and in contact with an outer circumferential surface of the first wiring and an outer circumferential surface of the second wiring, the first magnetic layer containing substantially spherical magnetic particles and a resin; a second magnetic layer having a third surface in contact with the first surface and a fourth surface spaced apart from the third surface in a thickness direction, the second magnetic layer containing substantially flat magnetic particles and a resin; a third magnetic layer having a fifth surface in contact with the second surface and a sixth surface spaced apart from the fifth surface in a thickness direction, the third magnetic layer containing substantially flat magnetic particles and a resin; the relative permeability of each of the second magnetic layer and the third magnetic layer is higher than the relative permeability of the first magnetic layer; the third surface has a first recess between a first opposing portion opposing the first wiring in a thickness direction and a second opposing portion opposing the second wiring in the thickness direction, the first recess being recessed from the first opposing portion and the second opposing portion; the fourth surface has a third opposing portion opposing the first opposing portion in the thickness direction and a fourth opposing portion opposing the second opposing portion in the thickness direction, the second recess being recessed between the third opposing portion and the fourth opposing portion, the fifth surface has a fifth opposing portion opposing the first wiring in a thickness direction and a sixth opposing portion opposing the second wiring in the thickness direction, and a third recess portion recessed from the fifth opposing portion and a sixth opposing portion between the fifth opposing portion and the sixth opposing portion, an inductor, characterized in that the sixth surface has a fourth recess recessed from a seventh opposing portion opposing the fifth opposing portion in the thickness direction and an eighth opposing portion opposing the second opposing portion in the thickness direction, between the seventh opposing portion and an eighth opposing portion.

2. a length L1 between the first opposing portion and the first wiring, a length L2 between the second opposing portion and the second wiring, and a depth L3 of the first recess satisfy the following formulas (1) and (2):

2. The inductor according to claim 1, wherein a length L4 between the fifth opposing portion and the first wiring, a length L5 between the sixth opposing portion and the second wiring, and a depth L6 of the third recess satisfy the following formulas (3) and (4): L3 / L1≧0.2 (1) L3 / L2≧0.2 (2) L6 / L4≧0.2 (3) L6 / L5≧0.2 (4)

3. a depth L3 of the first recess and a depth L7 of the second recess satisfy the following formula (5), 3. The inductor according to claim 1, wherein a depth L6 of the third recess and a depth L8 of the fourth recess satisfy the following formula (6): L7 / L3≧0.3 (5) L8 / L6≧0.3 (6)

4. a length L1 between the first opposing portion and the first wiring, and a length L9 in a thickness direction of the first wiring, satisfy the following formula (7): a length L2 between the second opposing portion and the second wiring, and a length L10 in a thickness direction of the second wiring, satisfy the following formula (8): a length L4 between the third opposing portion and the first wiring, and a length L9 of the first wiring, satisfy the following formula (9): The inductor according to any one of claims 1 to 3, characterized in that the length L5 between the fourth opposing portion and the second wiring and the length L10 of the second wiring satisfy the following formula (10): L1 / L9≧0.1 (7) L2 / L10≧0.1 (8) L4 / L9≧0.1 (9) L5 / L10≧0.1 (10)

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