inductor

Abstract

To provide an inductor that has excellent DC bias characteristics, can suppress decrease in inductance, and suppress crosstalk.SOLUTION: An inductor 1 includes a first magnetic layer 4 having first wiring 2 and second wiring 3 adjacent to each other with a gap therebetween, a first surface 11 continuous in the surface direction, a second surface 12 spaced apart from the first surface in the thickness direction and continuous in the surface direction, and an inner circumferential surface 10 in contact with the outer circumferential surfaces 17 of the first wiring and second wiring between the first and second surfaces, a second magnetic layer 5 disposed on the first surface, and a third magnetic layer 6 disposed on the second surface. The second magnetic layer and the third magnetic layer each have a higher relative permeability than the first magnetic layer. The inductor further includes a suppression portion 7 located between the first wiring and the second wiring when projected in the thickness direction, and suppressing magnetic coupling between the first wiring and the second wiring. The suppression portion includes a slit 21 located between the first surface and the third surface 13 and a slit 22 located between the second surface and the fourth surface 14.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] 2. Description of the Related Art It is known that inductors are mounted in electronic devices and used as passive elements such as voltage conversion members.

[0003] For example, an inductor has been proposed that includes a main body made of a magnetic material and an internal conductor made of copper embedded inside the main body (see, for example, Patent Document 1). [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] In recent years, with the trend toward smaller electronic devices with higher performance, similar characteristics are also required for inductors, and in order to increase inductance while reducing size, inductors with dense internal conductors are in demand.However, when an inductor has dense internal conductors, a problem occurs in which magnetic coupling (crosstalk) occurs between adjacent internal conductors due to the magnetic material.

[0006] On the other hand, if the interval between adjacent internal conductors is increased, the above-mentioned crosstalk can be suppressed, but this has the disadvantage of reducing inductance.

[0007] On the other hand, an inductor is also required to have excellent DC bias characteristics.

[0008] The present invention provides an inductor that has excellent DC bias characteristics, and is capable of suppressing crosstalk between adjacent wirings while suppressing a decrease in inductance. [Means for solving the problem]

[0009] The present invention (1) includes an inductor comprising: a first magnetic layer having a first wiring and a second wiring adjacent to each other with a gap therebetween, a first surface continuous in a surface direction, a second surface spaced from the first surface in a thickness direction and continuous in the surface direction, and an inner surface located between the first surface and the second surface and in contact with an outer surface of the first wiring and an outer surface of the second wiring; a second magnetic layer disposed on the first surface, and a third magnetic layer disposed on the second surface, the second magnetic layer having a third surface disposed opposite the first surface with a gap in the thickness direction, the second magnetic layer having a higher relative permeability than the relative permeability of the first magnetic layer, the inductor further comprising a suppression portion located between the first wiring and the second wiring when projected in the thickness direction and configured to suppress magnetic coupling between the first wiring and the second wiring, the suppression portion including a first suppression portion located between the first surface and the third surface.

[0010] In this inductor, the second magnetic layer and the third magnetic layer each have a higher relative permeability than the first magnetic layer, and the suppression section includes a first suppression section located between the first surface and the third surface, so that the inductor has excellent DC bias characteristics and can suppress a decrease in inductance while suppressing crosstalk between the first wiring and the second wiring.

[0011] The present invention (2) includes the inductor according to (1), in which the first suppression portion faces the first surface.

[0012] In this inductor, the first suppression portion faces the first surface, so that crosstalk between the first wiring and the second wiring can be effectively suppressed.

[0013] The present invention (3) includes the inductor according to (1) or (2), in which the first suppression portion is exposed from the third surface.

[0014] In this inductor, the first suppression portion is exposed from the third surface, and therefore the first suppression portion can be easily formed.

[0015] The present invention (4) includes an inductor described in any one of (1) to (3), wherein the length of the first suppression portion in the thickness direction is longer than the length of the first suppression portion in an adjacent direction in which the first wiring and the second wiring are adjacent to each other.

[0016] With this inductor, it is possible to effectively suppress crosstalk between the first wiring and the second wiring while minimizing the decrease in inductance.

[0017] The present invention (5) includes the inductor according to any one of (1) to (4), in which the first suppression portion is a slit formed in the second magnetic layer.

[0018] In this inductor, since the first suppression portion is a slit, the configuration is simple, and since air, which has the lowest relative permeability, is present in the slit, crosstalk between the first wiring and the second wiring can be reliably suppressed.

[0019] The present invention (6) includes the inductor according to any one of (1) to (4), wherein the first suppression portion is a first filling portion that fills a gap formed in the second magnetic layer, and the relative permeability of the first filling portion is lower than the relative permeability of the first magnetic layer.

[0020] In this inductor, the first suppression portion is the first filling portion having a lower relative magnetic permeability than the first magnetic layer, and therefore the first filling portion can reliably suppress crosstalk between the first wiring and the second wiring.

[0021] The present invention (7) includes the inductor according to any one of (1) to (6), further comprising a processing stabilizing layer disposed on the third surface of the second magnetic layer.

[0022] This inductor has a processing stability layer, and therefore the second magnetic layer has excellent processing stability.

[0023] The present invention (8) includes the inductor described in any one of (1) to (7), wherein the third magnetic layer has a fourth surface arranged opposite the second surface and spaced apart in the thickness direction, and the suppression portion further includes a second suppression portion located between the second surface and the fourth surface.

[0024] In this inductor, the suppression portion further includes a second suppression portion located between the second surface and the fourth surface, so that crosstalk between the first wiring and the second wiring can be further suppressed while suppressing a decrease in inductance.

[0025] The present invention (9) includes the inductor according to (8), in which the second suppression portion faces the second surface.

[0026] In this inductor, the second suppression portion faces the second surface, so that crosstalk between the first wiring and the second wiring can be effectively suppressed.

[0027] The present invention (10) includes the inductor according to (8) or (9), in which the second suppression portion is exposed from the fourth surface.

[0028] In this inductor, the second suppression portion is exposed from the fourth surface, and therefore the second suppression portion can be easily formed.

[0029] The present invention (11) includes an inductor according to any one of (8) to (10), wherein the length of the second suppression portion in the thickness direction is longer than the length of the second suppression portion in an adjacent direction in which the first wiring and the second wiring are adjacent to each other.

[0030] With this inductor, it is possible to effectively suppress crosstalk between the first wiring and the second wiring while minimizing the decrease in inductance.

[0031] A present invention (12) includes the inductor according to any one of (8) to (11), in which the second suppression portion is a second slit formed in the third magnetic layer.

[0032] In this inductor, the second suppression portion is the second slit, so that the configuration is simple, and since air, which has the lowest relative permeability, is present in the second slit, crosstalk between the first wiring and the second wiring can be reliably suppressed.

[0033] The present invention (13) includes the inductor according to any one of (8) to (11), wherein the second suppression portion is a second filling portion that fills a gap formed in the third magnetic layer, and the relative permeability of the second filling portion is lower than the relative permeability of the first magnetic layer.

[0034] In this inductor, the second suppression portion is the second filling portion having a lower relative magnetic permeability than the first magnetic layer, and therefore the second filling portion can reliably suppress crosstalk between the first wiring and the second wiring.

[0035] The present invention (14) includes the inductor according to any one of (8) to (13), further comprising a second process stabilizing layer disposed on the fourth surface of the third magnetic layer.

[0036] This inductor has the second processing stability, and therefore the surface processability of the third magnetic layer is excellent. Effect of the Invention

[0037] The inductor of the present invention has excellent DC bias characteristics, and can suppress a decrease in inductance while suppressing crosstalk between the first wiring and the second wiring. [Brief description of the drawings]

[0038] [Figure 1] FIG. 1 is a front cross-sectional view of an embodiment of an inductor of the present invention. [Diagram 2]2A to 2C illustrate a method for manufacturing the inductor shown in FIG. 1, with FIG. 2A showing the step of preparing first and second wirings and first to third magnetic sheets, FIG. 2B showing the step of hot pressing them, and FIG. 2C showing the step of forming a slit and a second slit. [Diagram 3] FIG. 3 is a front sectional view of a modified example (without the second slit) of the inductor shown in FIG. [Figure 4] FIG. 4 is a front sectional view of a modified example of the inductor shown in FIG. 1 (an embodiment in which the slit does not face the first surface, and the second slit does not face the second surface). [Diagram 5] FIG. 5 is a front sectional view of a modified example of the inductor shown in FIG. 1 (an embodiment in which the slit is not exposed from the third surface, and the second slit is not exposed from the fourth surface). [Figure 6] FIG. 6 is a front cross-sectional view of a modified example of the inductor shown in FIG. 1 (in which the slit does not face the first surface and is not exposed from the third surface, and the second slit does not face the second surface and is not exposed from the fourth surface). [Figure 7] FIG. 7 is a front sectional view of a modified example (in which the slit and the second slit communicate with each other) of the inductor shown in FIG. [Figure 8] FIG. 8 is a front sectional view of a modified example of the inductor shown in FIG. 1 (in which the slit communicates with the intermediate slit, and the second slit communicates with the second intermediate slit). [Figure 9] Figure 9 is a front cross-sectional view of a modified example of the inductor shown in Figure 1 (in which the length L2 of the slit in the thickness direction is shorter than the length L3 of the slit in the adjacent direction, and the length L4 of the second slit in the thickness direction is shorter than the length L5 of the second slit in the adjacent direction). [Figure 10] FIG. 10 is a front cross-sectional view of a modified example of the inductor shown in FIG. 1 (in which the recess and the second recess overlap the first wiring and the second wiring when projected in the adjacent direction). [Figure 11] FIG. 11 is a front sectional view of a modified example (in which the slit and the second slit are misaligned) of the inductor shown in FIG. [Figure 12]FIG. 12 is a front cross-sectional view of a modified example of the inductor shown in FIG. 1 (an embodiment in which the first suppression portion is the first filling portion, and the second suppression portion is the second filling portion). [Figure 13] FIG. 13 is a front sectional view of a modified example of the inductor shown in FIG. 12 (an embodiment in which the first filling portion is embedded in the second magnetic layer, and the second filling portion is embedded in the third magnetic layer). [Figure 14] FIG. 14 is a front cross-sectional view of a modified example of the inductor shown in FIG. 13 (in which the first filling portion and the second filling portion each have a generally circular cross-sectional shape). [Figure 15] FIG. 15 is a front sectional view of a modified example (in which the inner side surface and the second inner side surface are each tapered) of the inductor shown in FIG. [Figure 16] 16A to 16C illustrate a manufacturing method (including processing aspects) of a modified inductor, with FIG. 16B showing a step of arranging a processing stability layer and a second processing stability layer, and FIG. 16B showing a step of forming a slit and a second slit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] An embodiment of the inductor of the present invention will be described with reference to Figures 1 to 2C. In Figures 2A to 2C, in order to clearly show the relative positions of the first wiring 2, the second wiring 3, the first magnetic sheet 25, the third magnetic sheet 27, and the first magnetic layer 4, the third magnetic layer 6 (all of which will be described later), the conductive wire 8 and the insulating film 9 (described later) are omitted, and only the first wiring 2 and the second wiring 3 (described later) are depicted.

[0040] 1, the inductor 1 has a sheet shape extending in a planar direction. The inductor 1 includes a first wiring 2, a second wiring 3, a first magnetic layer 4, a second magnetic layer 5, a third magnetic layer 6, and a suppression section 7.

[0041] The first wiring 2 and the second wiring 3 are adjacent to each other with a gap therebetween. The first wiring 2 and the second wiring 3 are parallel to each other. Each of the first wiring 2 and the second wiring 3 has a substantially circular shape when cut in a cross section (front cross section) perpendicular to the direction in which current is transmitted (paper thickness direction in FIG. 1). Each of the first wiring 2 and the second wiring 3 includes a conductor 8 and an insulating film 9 that covers the conductor 8.

[0042] The conductor wire 8 is a conductor wire. The conductor wire 8 has a generally circular cross-sectional shape that shares a central axis with each of the first wiring 2 and the second wiring 3. Examples of materials for the conductor wire 8 include metal conductors such as copper, silver, gold, aluminum, nickel, and alloys thereof, and preferably copper. The conductor wire 8 may have a single-layer structure or a multi-layer structure in which the surface of a core conductor (e.g., copper) is plated (e.g., nickel) or the like. The diameter of the conductor wire 8 is, for example, 50 μm or more and 5000 μm or less.

[0043] The insulating film 9 protects the conductor 8 from chemicals and water, and prevents a short circuit between the conductor 8 and the first magnetic layer 4. The insulating film 9 covers the entire outer circumferential surface (circumferential surface) of the conductor 8. The insulating film 9 has a generally circular shape in cross section that shares a central axis (center) with each of the first wiring 2 and the second wiring 3. The insulating film 9 forms the outer circumferential surface 17 of each of the first wiring 2 and the second wiring 3. Examples of materials for the insulating film 9 include insulating resins such as polyvinyl formal, polyester, polyesterimide, polyamide (including nylon), polyimide, polyamideimide, and polyurethane. These may be used alone or in combination of two or more. The insulating film 9 may be composed of a single layer or multiple layers. The thickness of the insulating film 9 is, for example, 1 μm or more and 100 μm or less. The ratio of the radius of the conductor 8 to the thickness of the insulating film 9 is, for example, 2 or more and 500 or less.

[0044] The diameter L1 (average value of the maximum length) of each of the first wiring 2 and the second wiring 3 is, for example, not less than 25 μm and not more than 2000 μm.

[0045] The lower limit of the interval L between the adjacent first wiring 2 and second wiring 3 is, for example, 10, preferably 50, and the upper limit is, for example, 5,000, preferably 3,000. The upper limit of the ratio (L1 / L) of the diameter L1 of each of the first wiring 2 and second wiring 3 to the interval L between the adjacent first wiring 2 and second wiring 3 is, for example, 200, preferably 50, more preferably 30, and even more preferably 20, and the lower limit is, for example, 0.01. If the ratio (L1 / L) is equal to or less than the above upper limit, the decrease in inductance can be suppressed.

[0046] The first magnetic layer 4, the second magnetic layer 5 and the third magnetic layer 6 cooperate to improve the inductance of the inductor 1 and the DC bias characteristics of the inductor 1.

[0047] The first magnetic layer 4 has a sheet shape extending in both the longitudinal direction in which the first wiring 2 and the second wiring 3 extend and the adjacent direction in which the first wiring 2 and the second wiring 3 are adjacent to each other (plane direction). The first magnetic layer 4 has a first surface 11, a second surface 12, and an inner circumferential surface 10.

[0048] The first surface 11 is continuous in the plane direction of the first magnetic layer 4. The first surface 11 has a shape (e.g., a wave shape) corresponding to the first wiring 2 and the second wiring 3. The first surface 11 is located on one side of the first wiring 2 and the second wiring 3 in the thickness direction.

[0049] In particular, when the first surface 11 has the above-mentioned wave shape, it has protrusions 31 and recesses 32. The protrusions 31 are aligned along the outer circumferential surfaces 17 of the first wiring 2 and the second wiring 3.

[0050] The recess 32 is located between the two protrusions 31 and recessed toward the other side in the thickness direction. When projected in an adjacent direction, the recess 32 does not overlap the first wiring 2 and the second wiring 3, and is located on one side in the thickness direction of them.

[0051] The second surface 12 is spaced apart from the first surface 11 on the other side in the thickness direction. The second surface is continuous with the first magnetic layer 4 in the planar direction. The second surface 12 has a shape (e.g., a wave shape) corresponding to the first wiring 2 and the second wiring 3. The second surface 12 is located on the other side in the thickness direction than the first wiring 2 and the second wiring 3.

[0052] In particular, when the second surface 12 has the above-mentioned wave shape, it has second convex portions 33 and second concave portions 34. The second convex portions 33 extend along the outer circumferential surfaces 17 of the first wiring 2 and the second wiring 3.

[0053] The second recess 34 is located between the two second protrusions 33 and recessed toward one side in the thickness direction. When projected in an adjacent direction, the second recess 34 does not overlap the first wiring 2 and the second wiring 3, and is located on the other side in the thickness direction relative to them.

[0054] The inner circumferential surface 10 is located between the first surface 11 and the second surface 12. The inner circumferential surface 10 is formed midway through the thickness direction of the first magnetic layer 4. The inner circumferential surface 10 contacts and covers the outer circumferential surfaces 17 of the first wiring 2 and the second wiring 3.

[0055] The relative permeability and material of the first magnetic layer 4 will be described in detail later.

[0056] The second magnetic layer 5 is disposed on the first surface 11 of the first magnetic layer 4. The second magnetic layer 5 has a sheet shape extending in the planar direction. The second magnetic layer 5 has a third surface 13 and a fifth surface 15.

[0057] The third surface 13 is disposed opposite to and spaced from the first surface 11 on one side in the thickness direction. The third surface 13 forms one surface in the thickness direction of the inductor 1. The third surface 13 is flat, or may have a wave shape along the first surface 11, although not shown.

[0058] The fifth surface 15 is disposed on the other side in the thickness direction relative to the third surface 13 with a gap therebetween.

[0059] The relative permeability and material of the second magnetic layer 5 will be described in detail later.

[0060] The third magnetic layer 6 is disposed on the second surface 12 of the first magnetic layer 4. The third magnetic layer 6 has a sheet shape extending in the planar direction. The third magnetic layer 6 has a fourth surface 14 and a sixth surface 16.

[0061] The fourth surface 14 is disposed opposite to and spaced apart from the second surface 12 on the other side in the thickness direction. The fourth surface 14 forms the other surface in the thickness direction of the inductor 1. The fourth surface 14 is flat, or may have a wave shape along the second surface 12, although this is not shown.

[0062] The relative permeability of each of the second magnetic layer 5 and the third magnetic layer 6 is higher than that of the first magnetic layer 4. Since the relative permeability of each of the second magnetic layer 5 and the third magnetic layer 6 is higher than that of the first magnetic layer 4, the inductor 1 has excellent DC bias characteristics and can maintain a high inductance value.

[0063] The relative permeabilities of the first magnetic layer 4, the second magnetic layer 5, and the third magnetic layer 6 are all measured at a frequency of 10 MHz. The relative permeabilities of the first magnetic sheet 25, the second magnetic sheet 26, and the third magnetic sheet 27, which are precursors of the first magnetic layer 4, the second magnetic layer 5, and the third magnetic layer 6, are also measured in advance, and these can be considered to be substantially the same as the relative permeabilities of the first magnetic layer 4, the second magnetic layer 5, and the third magnetic layer 6.

[0064] Specifically, the lower limit of the ratio R1 of the relative permeability of the second magnetic layer 5 to the relative permeability of the first magnetic layer 4 is, for example, 1.1, preferably 1.5, more preferably 2, even more preferably 5, particularly preferably 10, and most preferably 15, and the upper limit is, for example, 10,000. The ratio R2 of the relative permeability of the third magnetic layer 6 to the relative permeability of the first magnetic layer 4 is the same as the above-mentioned R1. If the ratio R1 and / or the ratio R2 is equal to or greater than the above-mentioned lower limit, the DC bias characteristics are further improved.

[0065] The first magnetic layer 4, the second magnetic layer 5, and the third magnetic layer 6 all contain magnetic particles. Specifically, examples of materials for the first magnetic layer 4, the second magnetic layer 5, and the third magnetic layer 6 include magnetic compositions containing magnetic particles and a binder.

[0066] Examples of the magnetic material constituting the magnetic particles include soft magnetic materials and hard magnetic materials. From the viewpoint of inductance and DC bias characteristics, soft magnetic materials are preferable.

[0067] Examples of soft magnetic bodies include single metal bodies that contain 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 nonmetal elements (carbon, nitrogen, silicon, phosphorus, etc.). These can be used alone or in combination.

[0068] 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, for example, iron (Fe), cobalt (Co), nickel (Ni), or any other metal element that can be contained as the first metal element in a soft magnetic body.

[0069] In addition, the single metal body may be, for example, a form including a core containing only one type of metal element and a surface layer containing an inorganic and / or organic substance that modifies a part or the whole of the surface of the core, such as a form in which an organometallic compound or an inorganic metal compound containing a first metal element is decomposed (e.g., thermally decomposed). More specifically, the latter form may be iron powder (sometimes called carbonyl iron powder) obtained by thermally decomposing an organoiron compound (specifically, carbonyl iron) containing iron as the first metal element. The position of the layer containing an 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 that can obtain the single metal body is not particularly limited, and can be appropriately selected from known or commonly used organometallic compounds or inorganic metal compounds that can obtain a single metal body of a soft magnetic material.

[0070] 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-metallic 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.

[0071] The first metallic element is an essential element in the alloy body, and examples of the first metallic element 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.

[0072] 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 of the second metallic element 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 (Barium), and the like. 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), various rare earth elements, etc. These can be used alone or in combination of two or more.

[0073] The nonmetallic element is an element (secondary component) secondarily contained in the alloy body, and is a nonmetallic 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 kinds.

[0074] Examples of the alloy body include Fe-based alloys, such as 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, and 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.

[0075] Examples of the alloy body, which is a Co-based alloy, include Co-Ta-Zr and cobalt (Co)-based amorphous alloys.

[0076] An example of the alloy body is a Ni-based alloy, such as a Ni-Cr alloy.

[0077] The shape of the magnetic particles is not particularly limited, and examples include shapes that exhibit anisotropy, such as a roughly flat shape (plate shape) or a roughly needle shape (including a roughly spindle (football) shape), and shapes that exhibit isotropy, such as a roughly spherical shape, a roughly granular shape, or a roughly lump shape.

[0078] 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 can be calculated as the median particle size of the magnetic particles.

[0079] The lower limit of the volume proportion (filling rate) of the magnetic particles in the magnetic composition is, for example, 10 volume %, preferably 20 volume %, and the upper limit is, for example, 90 volume %, preferably 80 volume %.

[0080] Examples of the binder include thermoplastic components such as acrylic resins, and thermosetting components such as epoxy resin compositions. The acrylic resins include, for example, carboxyl-containing acrylic acid ester copolymers. The epoxy resin compositions include, for example, an epoxy resin (such as cresol novolac epoxy resin) as a base, a curing agent for epoxy resins (such as phenolic resins), and a curing accelerator for epoxy resins (such as imidazole compounds).

[0081] As the binder, a thermoplastic component and a thermosetting component can be used alone or in combination, and it is preferable to use a thermoplastic component and a thermosetting component in combination.

[0082] A more detailed formulation of the above-mentioned magnetic composition is described in, for example, JP-A-2014-165363.

[0083] The type, shape, size, volume ratio, etc. of the magnetic particles in the magnetic composition are appropriately changed so that the relative magnetic permeability of the second magnetic layer 5 and the third magnetic layer 6 is higher than that of the first magnetic layer 4.

[0084] As an example of the shape of the magnetic particles, the material of the first magnetic layer 4 contains magnetic particles having a substantially spherical shape, and the materials of the second magnetic layer 5 and the third magnetic layer 6 all contain magnetic particles having a substantially flat shape (for example, Examples 1 to 4 described later). Alternatively, all of the materials of the first magnetic layer 4, the second magnetic layer 5 and the third magnetic layer 6 all contain magnetic particles having a substantially spherical shape (for example, Examples 5 to 8 described later).

[0085] The suppression portion 7 is configured to suppress magnetic coupling between the first wiring 2 and the second wiring 3. The suppression portion 7 is located between the first wiring 2 and the second wiring 3 when projected in the thickness direction. Specifically, when projected in the thickness direction, the suppression portion 7 does not overlap either the first wiring 2 or the second wiring 3. When projected in the thickness direction, the suppression portion 7 is located between a first point 51 that is closest to the second wiring 3 on the outer peripheral surface 17 of the first wiring 2, and a second point 52 that is closest to the first wiring 2 on the outer peripheral surface 17 of the second wiring 3.

[0086] The suppression portion 7 includes a slit 21 as an example of a first suppression portion, and a second slit 22 as an example of a second suppression portion. In this embodiment, the suppression portion 7 preferably includes only the slit 21 and the second slit 22.

[0087] The slit 21 is located between the first surface 11 and the third surface 13. More specifically, the suppression section 7 is formed over the entire thickness direction of the second magnetic layer 5. More specifically, the slit 21 penetrates the second magnetic layer 5 in the thickness direction. However, the slit 21 penetrates the second magnetic layer 5 but does not penetrate or cut out the first magnetic layer 4. The slit 21 faces the first surface 11. That is, the slit 21 exposes the corresponding first surface 11 (the recess 32 therein). The slit 21 is also exposed from the third surface 13. In other words, the slit 21 is open toward one side in the thickness direction. The slit 21 is partitioned by the recess 32 on the first surface 11 of the first magnetic layer 4 and the two inner surfaces 23 of the second magnetic layer 5 that expose it. The two inner surfaces 23 are spaced apart from each other at the same interval in the thickness direction, and more specifically, are parallel to each other.

[0088] The length L2 of the slit 21 in the thickness direction is longer than the length L3 of the slit 21 in the adjacent direction. The ratio (L2 / L3) of the length L2 of the slit 21 in the thickness direction to the length L3 of the slit 21 in the adjacent direction exceeds 1, and specifically, the lower limit of the ratio (L2 / L3) is, for example, 1.5, preferably 3, more preferably 5, and even more preferably 10, and the upper limit is, for example, 1,000. If the ratio (L2 / L3) is equal to or greater than the above-mentioned lower limit, crosstalk between the first wiring 2 and the second wiring 3 can be effectively suppressed.

[0089] The upper limit of the ratio (L3 / L) of the length L3 of the slit 21 in the adjacent direction to the interval L between the adjacent first wirings 2 and second wirings 3 is, for example, 0.95, or preferably 0.9, and the lower limit is, for example, 0.0001.

[0090] Specifically, the upper limit of the length L3 of the slit 21 in the adjacent direction is, for example, 1,000 μm, preferably 700 μm, preferably 500 μm, more preferably 300 μm, and the lower limit is, for example, 5 μm.

[0091] The second slit 22 is located between the second surface 12 and the fourth surface 14. More specifically, the suppression section 7 is formed over the entire thickness direction of the third magnetic layer 6. The second slit 22 is formed in the third magnetic layer 6. More specifically, the second slit 22 penetrates the third magnetic layer 6 in the thickness direction. However, the second slit 22 penetrates the third magnetic layer 6 but does not penetrate or notch the first magnetic layer 4. The second slit 22 faces the second surface 12. That is, the second slit 22 exposes the corresponding third surface 13 (the second recess 34 of the third surface 13). The second slit 22 is also exposed from the fourth surface 14. In other words, the second slit 22 is open toward the other side in the thickness direction. The second slit 22 is partitioned by the second recess 34 of the second surface 12 and the two second inner surfaces 24 of the third magnetic layer 6 that expose it. The two second inner surfaces 24 have the same distance therebetween in the thickness direction, and specifically, are parallel to each other.

[0092] The length L4 of the second slit 22 in the thickness direction is longer than the length L5 of the second slit 22 in the adjacent direction. The lower limit of the ratio (L4 / L5) of the length L4 of the second slit 22 in the thickness direction to the length L5 of the second slit 22 in the adjacent direction exceeds 1, and specifically, the ratio (L4 / L5) is, for example, 1.5, preferably 3, more preferably 5, and even more preferably 10, and the upper limit is, for example, 1,000. If the ratio (L4 / L5) is equal to or greater than the above-mentioned lower limit, crosstalk between the first wiring 2 and the second wiring 3 can be effectively suppressed.

[0093] The lower limit of the ratio (L5 / L) of the length L5 of the second slit 22 in the adjacent direction to the interval L between the adjacent first wirings 2 and second wirings 3 is, for example, 0.95, preferably 0.9, and the upper limit is, for example, 0.0001.

[0094] Specifically, the length L5 of the second slit 22 in the adjacent direction is the same as the length L3 of the slit 21 in the adjacent direction described above.

[0095] The thickness of inductor 1 is the length between third surface 13 and fourth surface 14. Specifically, the lower limit of the thickness of inductor 1 is, for example, 30 μm, or preferably 50 μm, and the upper limit is, for example, 10,000 μm, or preferably 2,000 μm.

[0096] To obtain the inductor 1, first, a first wiring 2, a second wiring 3, two first magnetic sheets 25, one second magnetic sheet 26, and one third magnetic sheet 27 are prepared, as shown in FIG. 2A.

[0097] The two first magnetic sheets 25 are precursor sheets for forming the first magnetic layer 4. The second magnetic sheet 26 is a precursor sheet for forming the second magnetic layer 5. The third magnetic sheet 27 is a precursor sheet for forming the third magnetic layer 6. These precursor sheets are, for example, in the B stage.

[0098] The second magnetic sheet 26, one of the first magnetic sheets 25, the first wiring 2 and the second wiring 3, the other of the first magnetic sheet 25, and the third magnetic sheet 27 are arranged in that order toward the other side in the thickness direction.

[0099] Next, these are heat-pressed in the thickness direction. The two first magnetic sheets 25 are deformed so as to bury the first wiring 2 and the second wiring 3, and become the first magnetic layer 4. The second magnetic sheet 26 is deformed so as to conform to the first surface 11, and becomes the second magnetic layer 5. The third magnetic sheet 27 is deformed so as to conform to the second surface 12, and becomes the third magnetic layer 6. The precursor sheets (first magnetic sheet 25 to third magnetic sheet 27) are brought to the C stage by the above-mentioned heat pressing. As a result, an inductor 1 is obtained that does not include the suppression section 7 and includes the first magnetic layer 4 to the third magnetic layer 6.

[0100] 2C, the slits 21 and the second slits 22 are then formed in the second magnetic layer 5 and the third magnetic layer 6 of the inductor 1, respectively. To form the slits 21 and the second slits 22, for example, a cutting device is used.

[0101] Examples of cutting devices include contact cutting devices, such as dicing devices, that come into physical contact with the second magnetic layer 5 and / or the third magnetic layer 6, and non-contact cutting devices, such as laser devices, that do not come into physical contact with the second magnetic layer 5 and / or the third magnetic layer 6.

[0102] A dicing device, which is an example of a contact-type cutting device, includes a support table (not shown), a dicing saw 28 arranged facing the support table with a gap therebetween, and a moving device (not shown) for moving the dicing saw 28. The dicing saw 28 may be, for example, a dicing blade having a disk shape.

[0103] In this way, the inductor 1 including the suppression portion 7 having the slit 21 and the second slit 22 is manufactured.

[0104] <Effects of one embodiment> In this inductor 1, the second magnetic layer 5 and the third magnetic layer 6 each have a higher relative permeability than the first magnetic layer 4, and the suppression section 7 includes a slit 21 located between the first surface 11 and the third surface 13. Therefore, the inductor 1 has excellent DC superposition characteristics, and can suppress a decrease in inductance while suppressing crosstalk between the first wiring 2 and the second wiring 3.

[0105] In this inductor 1, the slits 21 face the first surface 11, so that crosstalk between the first wiring 2 and the second wiring 3 can be effectively suppressed.

[0106] In this inductor 1, the slits 21 are exposed from the third surface 13, and therefore the slits 21 can be easily formed.

[0107] In this inductor 1, the length L2 of the slit 21 in the thickness direction is longer than the length L3 of the slit 21 in the adjacent direction, so that crosstalk between the first wiring 2 and the second wiring 3 can be effectively suppressed while minimizing the decrease in inductance.

[0108] In this inductor 1, the first suppression part is the slit 21, so that while the configuration is simple, the slit 21 contains air, which has the lowest relative permeability of 1, and therefore the slit 21 can reliably suppress crosstalk between the first wiring 2 and the second wiring 3.

[0109] In this inductor 1, the suppression section 7 further includes a second slit 22 located between the second surface 12 and the fourth surface 14, thereby suppressing crosstalk between the first wiring 2 and the second wiring 3 while suppressing a decrease in inductance.

[0110] In this inductor 1, the second slits 22 face the second surface 12, so that crosstalk between the first wiring 2 and the second wiring 3 can be effectively suppressed.

[0111] In this inductor 1, the slits 21 are exposed from the third surface 13, and therefore the slits 21 can be easily formed.

[0112] In this inductor 1, the length L4 of the second slit 22 in the thickness direction is longer than the length L5 of the second slit 22 in the adjacent direction, so that crosstalk between the first wiring 2 and the second wiring 3 can be effectively suppressed while minimizing the decrease in inductance.

[0113] In this inductor 1, the second suppression section is the second slit 22, so that the configuration is simple, and since air, which has the lowest relative permeability of 1, is present in the slit 21, crosstalk between the first wiring 2 and the second wiring 3 can be reliably suppressed.

[0114] <Modification> In the modified example, the same components and steps as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. In addition, the modified example can achieve the same effects as those in the first embodiment, unless otherwise specified. Furthermore, the first embodiment and its modified example can be appropriately combined.

[0115] 3, in this inductor 1, the suppression section 7 does not have the second slit 22 (see FIG. 1), and only has the slit 21. Preferably, from the viewpoint of efficiently suppressing crosstalk between the first wiring 2 and the second wiring 3, the suppression section 7 has the slit 21 and the second slit 22.

[0116] 4, the slit 21 does not face the first surface 11, and is spaced apart from the first surface 11 in the thickness direction. The second slit 22 does not face the second surface 12, and is spaced apart from the second surface 12 in the thickness direction. Preferably, as in one embodiment, the slit 21 faces the first surface 11, and the second slit 22 faces the second surface 12.

[0117] 5, the slit 21 is not exposed from the third surface 13, and one edge in the thickness direction of the slit 21 is blocked by the second magnetic layer 5. The second slit 22 is not exposed from the fourth surface 14, and the other edge in the thickness direction of the second slit 22 is blocked by the third magnetic layer 6. Preferably, as in one embodiment, the slit 21 is exposed from the third surface 13, and the second slit 22 is exposed from the fourth surface 14.

[0118] 6, the slit 21 does not face the first surface 11, and is not exposed from the third surface 13. The slit 21 is located in the middle of the first surface 11 and the third surface 13 in the thickness direction. The second slit 22 does not face the second surface 12, and is not exposed from the fourth surface 14. The second slit 22 is located in the middle of the second surface 12 and the fourth surface 14 in the thickness direction.

[0119] 7, the slit 21 and the second slit 22 communicate with each other via an intermediate slit 29. The intermediate slit 29 is located between the first surface 11 and the second surface 12. The intermediate slit 29 penetrates the first magnetic layer 4 in the thickness direction. Preferably, as in one embodiment, the intermediate slit 29 is not formed in the inductor 1.

[0120] 8, the slit 21 communicates with an intermediate slit 29. The intermediate slit 29 is cut out from the first surface 11 of the first magnetic layer 4 toward the middle part in the thickness direction. The second slit 22 communicates with a second intermediate slit 30. The second intermediate slit 30 is cut out from the second surface 12 of the first magnetic layer 4 toward the middle part in the thickness direction. The second intermediate slit 30 is disposed opposite to the intermediate slit 29 with a gap therebetween in the thickness direction.

[0121] 9, the length L2 of the slit 21 in the thickness direction is shorter than the length L3 of the slit 21 in the adjacent direction. Although not shown, the lengths L2 and L3 of the slit 21 may be the same. The upper limit of the ratio (L2 / L3) of the length L2 of the slit 21 in the thickness direction to the length L3 of the slit 21 in the adjacent direction is, for example, not more than 1, preferably less than 1, and the lower limit of the ratio (L2 / L3) is 0.01, preferably 0.05, more preferably 0.1, and even more preferably 0.2.

[0122] The length L4 of the second slit 22 in the thickness direction is shorter than the length L5 of the second slit 22 in the adjacent direction. Although not shown, the lengths L4 and L5 of the second slit 22 may be the same. The upper limit of the ratio (L4 / L5) of the length L4 of the second slit 22 in the thickness direction to the length L5 of the second slit 22 in the adjacent direction is, for example, 1 or less, preferably less than 1, and the lower limit of the ratio (L2 / L3) is 0.01, preferably 0.05, more preferably 0.1, and even more preferably 0.2.

[0123] 10, the recess 32 on the first surface 11 overlaps with the first wiring 2 and the second wiring 3 when projected in an adjacent direction. The second recess 34 on the second surface 12 overlaps with the first wiring 2 and the second wiring 3 when projected in an adjacent direction.

[0124] As shown in FIG. 11, when projected in the thickness direction, the slit 21 and the second slit 22 are shifted (offset) in the adjacent direction.

[0125] 12, a first filling portion 37 is filled in the gap 35 which is the slit 21. A second filling portion 38 is filled in the gap 35 which is the second slit 22.

[0126] 13, the first filling portion 37 is not exposed from the third surface 13 and is buried by the second magnetic layer 5. The second filling portion 38 is not exposed from the fourth surface 14 and is buried by the third magnetic layer 6. Each of the first filling portion 37 and the second filling portion 38 has a generally rectangular shape in cross section. The relative magnetic permeability of each of the first filling portion 37 and the second filling portion 38 is lower than the relative magnetic permeability of the first magnetic layer 4.

[0127] The material of each of the first filling portion 37 and the second filling portion 38 may be, for example, a non-magnetic composition that does not contain magnetic particles but contains a binder. The binder is exemplified by the magnetic composition described above.

[0128] To obtain this inductor 1, as shown in FIG. 2A, first, two first magnetic sheets 25, a first wiring 2 and a second wiring 3 are prepared and then heat-pressed. When the first magnetic sheet 25 contains a thermosetting component, it is heat-pressed to a C-stage. This forms the first magnetic layer 4. Next, the first filling portion 37 and the second filling portion 38, which are solid at room temperature, are placed in the recess 32 on the first surface 11 and the second recess 34 on the second surface 12, respectively, and then they are sandwiched between the second magnetic sheet 26 and the third magnetic sheet 27, and then heat-pressed. This forms the second magnetic layer 5 in which the first filling portion 37 is embedded, and the third magnetic layer 6 in which the second filling portion 38 is embedded.

[0129] As shown in FIG. 14, each of the first filling portion 37 and the second filling portion 38 has a generally circular shape in cross section.

[0130] 15, the two inner sides 23 defining the slit 21 have a tapered shape in which the opposing length gradually decreases from the third surface 13 toward the first surface 11. The two second inner sides 24 defining the second slit 22 have a tapered shape in which the opposing length gradually decreases from the fourth surface 14 toward the second surface 12.

[0131] The first magnetic sheet 25 can be made up of multiple sheets depending on the desired thickness of the first magnetic layer 4. The second magnetic sheet 26 can be made up of multiple sheets depending on the desired thickness of the second magnetic layer 5. The third magnetic sheet 27 can be made up of multiple sheets depending on the desired thickness of the third magnetic layer 6.

[0132] Although not shown, the shapes of the first wiring 2 and the third wiring 3 are not particularly limited, and may be, for example, rectangular in cross section.

[0133] Although not shown, the second magnetic layer 5 in which the slits 21 are formed in advance can be attached to the first surface 11 of the first magnetic layer 4. The third magnetic layer 6 in which the second slits 22 are formed in advance can be attached to the second surface 12 of the first magnetic layer 4.

[0134] As shown in FIG. 16B, the inductor 1 can further include a processing stability layer 71 and a processing stability layer 72.

[0135] The processing stabilizing layer 71 and the processing stabilizing layer 72 improve the surface processability of the third surface 13 of the second magnetic layer 5 and the fourth surface 14 of the third magnetic layer 6, respectively.

[0136] The processing stabilizing layer 71 is disposed on the third surface 13 of the second magnetic layer 5. The processing stabilizing layer 71 also has slits 21 formed therein. The processing stabilizing layer 71 is in contact with the entire third surface 13.

[0137] The processing stabilizing layer 71 contains a cured product of a thermosetting resin composition. That is, the material of the processing stabilizing layer 71 contains a thermosetting resin composition.

[0138] The thermosetting resin composition contains a thermosetting resin as an essential component, and contains particles as an optional component.

[0139] The thermosetting resin includes a base resin, a curing agent, and a curing accelerator.

[0140] Examples of the base resin include epoxy resins and silicone resins, and preferably epoxy resins. Examples of the epoxy resin include bifunctional epoxy resins such as bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, modified bisphenol A type epoxy resins, modified bisphenol F type epoxy resins, modified bisphenol S type epoxy resins, and biphenyl type epoxy resins, and polyfunctional epoxy resins having three or more functional groups such as phenol novolac type epoxy resins, cresol novolac type epoxy resins, trishydroxyphenylmethane type epoxy resins, tetraphenylolethane type epoxy resins, and dicyclopentadiene type epoxy resins. These epoxy resins can be used alone or in combination of two or more kinds. Preferably, bifunctional epoxy resins are used, and more preferably, bisphenol A type epoxy resins are used.

[0141] The lower limit of the epoxy equivalent of the epoxy resin is, for example, 10 g / eq., and the upper limit is, for example, 1,000 g / eq.

[0142] If the main agent is an epoxy resin, the curing agent may be, for example, a phenol resin or an isocyanate resin. The phenol resin may be, for example, a polyfunctional phenol resin such as a phenol novolac resin, a cresol novolac resin, a phenol aralkyl resin, a phenol biphenylene resin, a dicyclopentadiene type phenol resin, or a resol resin. These may be used alone or in combination of two or more. The phenol resin may preferably be a phenol novolac resin or a phenol biphenylene resin. If the main agent is an epoxy resin and the curing agent is a phenol resin, the lower limit of the total of the hydroxyl groups in the phenol resin relative to 1 equivalent of the epoxy group in the epoxy resin is, for example, 0.7 equivalents, preferably 0.9 equivalents, and the upper limit is, for example, 1.5 equivalents, preferably 1.2 equivalents. Specifically, the lower limit of the mass parts of the curing agent is, for example, 1 part by mass, or, for example, 50 parts by mass, relative to 100 parts by mass of the main agent.

[0143] The curing accelerator is a catalyst (thermosetting catalyst) (preferably an epoxy resin curing accelerator) that accelerates the curing of the base agent, and examples thereof include organic phosphorus compounds, such as imidazole compounds such as 2-phenyl-4-methyl-5-hydroxymethylimidazole (2P4MHZ). The lower limit of the number of parts by mass of the curing accelerator is, for example, 0.05 parts by mass, and the upper limit is, for example, 5 parts by mass, relative to 100 parts by mass of the base agent.

[0144] The particles are an optional component in the thermosetting resin composition. The particles are dispersed in the thermosetting resin. The particles are at least one type selected from the group consisting of first particles and second particles.

[0145] The first particles have a substantially spherical shape. The lower limit of the median diameter of the first particles is, for example, 1 μm, preferably 5 μm, and the upper limit of the median diameter of the first particles is, for example, 250 μm, preferably 200 μm. The median diameter of the first particles is determined by a laser diffraction particle size distribution measuring device. The median diameter of the first particles can also be determined, for example, by binarization processing based on cross-sectional observation of the laminate sheet 1.

[0146] The material of the first particles is not particularly limited. Examples of the material of the first particles include metals, inorganic compounds, and organic compounds, and in order to increase the thermal expansion coefficient, metals and inorganic compounds are preferable.

[0147] The metal is contained in the thermosetting resin composition when the processing stabilizing layer 71 is made to function as an inductance improving layer. Examples of the metal include the magnetic materials exemplified in the magnetic layer 5, and preferably include an organic iron compound containing iron as the first metal element, and more preferably, carbonyl iron.

[0148] The inorganic compound is contained in the thermosetting resin composition when the processing stabilizing layer 71 is made to function as a thermal expansion coefficient suppressing layer. Examples of the inorganic compound include inorganic fillers, specifically, silica, alumina, and the like, and preferably, silica.

[0149] Specifically, the first particles are preferably spherical silica, and are preferably spherical carbonyl iron.

[0150] The second particles have a substantially flat shape, which includes a substantially plate shape.

[0151] The lower limit of the flattening ratio (flatness) of the second particles is, for example, 8, or preferably 15, and the upper limit is, for example, 500, or preferably 450. The flattening ratio of the second particles is calculated by the same method as the flattening ratio of the magnetic particles in the magnetic layer 5 described above.

[0152] The lower limit of the median diameter of the second particles is, for example, 1 μm, or preferably 5 μm, and the upper limit of the median diameter of the second particles is, for example, 250 μm, or preferably 200 μm. The median diameter of the second particles is determined in the same manner as that of the first particles.

[0153] The lower limit of the average thickness of the second particles is, for example, 0.1 μm, preferably 0.2 μm, and the upper limit is, for example, 3.0 μm, preferably 2.5 μm.

[0154] The material of the second particles is an inorganic compound. Examples of the inorganic compound include thermally conductive compounds such as boron nitride. Therefore, the inorganic compound is preferably included in the thermosetting resin composition when the processing stabilizing layer 71 is made to function as a thermal conductivity improving layer.

[0155] Specifically, the second particles are preferably flat-shaped boron nitride particles.

[0156] The thermosetting resin composition may contain a single type of the first particles and a single type of the second particles, or may contain both of them.

[0157] The lower limit of the number of parts by mass of the particles (first particles and / or second particles) relative to 100 parts by mass of the thermosetting resin is, for example, 10 parts by mass, preferably 50 parts by mass, and the upper limit is, for example, 2,000 parts by mass, preferably 1,500 parts by mass. The lower limit of the content ratio of the particles in the cured product is, for example, 10% by mass, and the upper limit is, for example, 90% by mass. When both the first particles and the second particles are contained in the thermosetting resin composition, the lower limit of the number of parts by mass of the second particles relative to 100 parts by mass of the first particles is, for example, 30 parts by mass, and the upper limit is, for example, 300 parts by mass.

[0158] Since particles are an optional component in a thermosetting resin composition, the thermosetting resin composition does not necessarily need to contain particles.

[0159] The lower limit of the thickness of the processing stabilizing layer 71 is, for example, 1 μm, preferably 10 μm, and the upper limit is, for example, 1,000 μm, preferably 100 μm. The lower limit of the ratio of the thickness of the processing stabilizing layer 71 to the thickness of the laminated sheet 1 is, for example, 0.001, preferably 0.005, more preferably 0.01, and the upper limit is, for example, 0.5, preferably 0.3, more preferably 0.1.

[0160] The material and dimensions of the second shaping stabilizing layer 72 are similar to those of the shaping stabilizing layer 71 .

[0161] To manufacture an inductor 1 having a process stabilizing layer 71 and a second process stabilizing layer 72, an inductor 1 without a suppression section 7 is produced as shown in Figure 2B, and then two process stabilizing sheets 73 are placed (laminated) on each of the third surface 13 and the fourth surface 14, as shown in Figure 16A.

[0162] The processing stabilizing sheet 73 is formed in a sheet shape from the materials of the processing stabilizing layer 71 and the second processing stabilizing layer 72. The processing stabilizing sheet 73 preferably contains a B-stage thermosetting resin composition.

[0163] The above-mentioned material can be prepared as a varnish by further mixing a solvent with the above-mentioned thermosetting resin composition. Furthermore, the material can further include a thermoplastic resin.

[0164] Examples of the solvent include alcohol compounds such as methanol, ether compounds such as dimethyl ether, and ketone compounds such as methyl ethyl ketone, cyclohexanone, etc. The mixing ratio of the solvent is adjusted so that the lower limit of the mass ratio of the solid content in the varnish is, for example, 10 mass%, and the upper limit is, for example, 95 mass%.

[0165] In this method, varnish is applied to the surface of a release sheet (not shown) and dried to form two process-stabilizing sheets 73 .

[0166] Next, two processing stabilizing sheets 73 are pressed from both sides in the thickness direction. The two processing stabilizing sheets 73 are attached to the third surface 13 and the fourth surface 14, respectively.

[0167] Then, they are heated to bring the processing stabilizing sheet 73 to the C stage. As a result, the slits 21 are formed in the processing stabilizing layer 71 and the second magnetic layer 5. Also, the second slits 22 are formed in the second processing stabilizing layer 72 and the third magnetic layer 6. As a result, the laminated sheet 1 is obtained in which the slits 21 and the second slits 22 are formed in the processing stabilizing layer 71 and the second magnetic layer 5, and the second processing stabilizing layer 72 and the third magnetic layer 6, respectively.

[0168] Since the inductor 1 of the modified example includes the processing stabilizing layer 71, the processing stability of the second magnetic layer 5 is excellent.

[0169] More specifically, although not shown, if the inductor 1 does not include the process stabilizing layer 71 and consists only of the inductor 2, when the slit 21 is formed in the second magnetic layer 5, the inner end of the third surface 13 of the second magnetic layer 5 facing the slit 21 will warp (rise up) to one side in the thickness direction. This phenomenon occurs because, when the slit 21 is formed in the second magnetic layer 5, the magnetic particles are made of metals and therefore not easily broken, and because they have a substantially flat shape, the second magnetic layer 5 moves to one side in the thickness direction while drawing in the binder around the magnetic particles.

[0170] However, the inductor 1 of this embodiment has a process-stabilizing layer 71, as shown in FIG. 16B, which contains at least one type of particle selected from the group consisting of first particles and second particles as an optional component.

[0171] Specifically, when the processing stabilization layer 71 does not contain particles, there is no deformation of the processing stabilization layer 71 due to the movement of the particles described above, and therefore the hardened material in the processing stabilization layer 71 can suppress deformation of the second magnetic layer 5.

[0172] When the processing stabilizing layer 71 contains the first particles having a substantially spherical shape, the movement of the first particles in the processing stabilizing layer 71 while involving the surrounding binder is suppressed. Therefore, the hardened material in the processing stabilizing layer 71 can suppress deformation of the second magnetic layer 5.

[0173] When the processing stabilizing layer 71 contains second particles made of an inorganic compound, even if the second particles have a substantially flat shape, the second particles are likely to break when the slits 21 are formed in the second magnetic layer 5 because the material of the second particles is a brittle inorganic compound. Therefore, the movement of the second particles in the processing stabilizing layer 71 is suppressed. As a result, the hardened material in the processing stabilizing layer 71 can suppress deformation of the second magnetic layer 5.

[0174] Therefore, since the inductor 1 of the modified example includes the above-mentioned process stabilizing layer 71, deformation of the second magnetic layer 5 can be suppressed when the slits 21 are formed in the inductor 1.

[0175] Furthermore, since the inductor 1 of the first modified example includes the above-mentioned second process stabilizing layer 72, deformation of the third magnetic layer 6 can be suppressed when the slits 22 are formed in the inductor 1 for the reasons described above.

[0176] Although not shown, the inductor 1 may be provided with only the processing stabilizing layer 71 without providing the second processing stabilizing layer 72.

[0177] Moreover, the inductor 1 of the above-described modified example (preferably the inductor 1 including the process stabilizing layer 71 and the second process stabilizing layer 72) satisfies at least one of the tests (a) to (e), for example.

[0178] Test (a): Inductor 1 is machined to a 3 cm square to create a sample, and its relative permeability μ1 at a frequency of 10 MHz is determined. The sample is then immersed in 200 mL of copper sulfate plating solution containing 66 g / L copper sulfate pentahydrate, 180 g / L sulfuric acid, 50 ppm chlorine, and top lutina at 25°C for 120 minutes, and the relative permeability μ2 at a frequency of 10 MHz is then determined. The rate of change in permeability before and after immersion is calculated using the following formula. As a result, the rate of change in magnetic permeability of the sample was 5% or less.

[0179] Permeability change rate (%) = |μ1-μ2| / μ1×100 Test (b): A sample is made by cutting the inductor 1 into a 3 cm square shape, and its relative permeability μ3 at a frequency of 10 MHz is determined. The sample is then immersed in 200 mL of an acid activation aqueous solution containing 55 g / L of sulfuric acid at 25°C for 1 minute, and then the relative permeability μ4 of the sample at a frequency of 10 MHz is determined. The rate of change in permeability before and after immersion is calculated using the following formula. As a result, the rate of change in the sample's permeability is 5% or less.

[0180] Permeability change rate (%) = |μ3-μ4| / μ3×100 Test (c): Inductor 1 is machined to a 3 cm square to create a sample, and its relative permeability μ5 at a frequency of 10 MHz is determined. The sample is then immersed in 200 mL of Atotech Japan's Reduction Solution Securiganth P at 45°C for 5 minutes, and the relative permeability μ6 of the sample at a frequency of 10 MHz is then determined. The rate of change in permeability before and after immersion is calculated using the following formula. As a result, the rate of change in the sample's permeability is 5% or less.

[0181] Permeability change rate (%) = |μ5-μ6| / μ5×100 Test (d): A sample is made by cutting the inductor 1 into a 3 cm square shape, and its relative permeability μ7 at a frequency of 10 MHz is determined. The sample is then immersed in 200 mL of Concentrate Compact CP manufactured by Atotech Japan at 80°C for 15 minutes, and the relative permeability μ8 of the sample at a frequency of 10 MHz is then determined. The rate of change in permeability before and after immersion is calculated using the formula below. As a result, the rate of change in the sample's permeability is 5% or less.

[0182] Permeability change rate (%) = |μ7-μ8| / μ7×100 Test (e): Inductor 1 is machined to a 3 cm square to create a sample, and its relative permeability μ9 at a frequency of 10 MHz is determined. The sample is then immersed in 200 mL of Swelling Dip Securigant P manufactured by Atotech Japan at 60°C for 5 minutes, and the relative permeability μ10 of the sample at a frequency of 10 MHz is then determined. The rate of change in permeability before and after immersion is calculated using the following formula. As a result, the rate of change in the sample's permeability is 5% or less.

[0183] Permeability change rate (%) = |μ9-μ10| / μ9×100 In the case where test (a) is satisfied, the upper limit of the percent change in magnetic permeability of the sample in test (a) is preferably 4%, more preferably 3%.

[0184] If the test (a) is satisfied, the inductor 1 has excellent stability when immersed in a copper sulfate solution for electrolytic copper plating.

[0185] In the case where test (b) is satisfied, the upper limit of the percentage change in magnetic permeability of the sample in test (b) is preferably 4%, more preferably 3%.

[0186] If the test (b) is satisfied, the inductor 1 has excellent stability against immersion in an acid activation solution.

[0187] In the case where test (c) is satisfied, the upper limit of the percent change in magnetic permeability of the sample in test (c) is preferably 4%, more preferably 3%.

[0188] The reduction solution Securiganth P manufactured by Atotech Japan in test (c) contains an aqueous sulfuric acid solution and is used as a neutralizing liquid (neutralizing agent or aqueous solution for neutralization). Therefore, if the test (c) is satisfied, the inductor 1 has excellent stability against immersion in a neutralizing liquid.

[0189] In the case where test (d) is satisfied, the upper limit of the percent change in magnetic permeability of the sample in test (d) is preferably 4%, more preferably 3%.

[0190] The Concentrate Compact CP manufactured by Atotech Japan in test (d) contains a potassium permanganate solution. Therefore, if test (d) is satisfied, the inductor 1 has excellent stability against immersion in a potassium permanganate solution for desmear (cleaning).

[0191] In the case where test (e) is satisfied, the upper limit of the percent change in magnetic permeability of the sample in test (e) is preferably 4%, more preferably 3%.

[0192] In the test (e), Swelling Dip Securigant P manufactured by Atotech Japan is an aqueous solution containing glycol ethers and sodium hydroxide, and is used as the swelling liquid. Therefore, if the test (e) is satisfied, the inductor 1 has excellent stability against immersion in a swelling liquid.

[0193] Preferably, all of tests (a) to (e) are satisfied, and therefore the inductor 1 has excellent stability against immersion in a copper sulfate solution for electrolytic copper plating, an acid activation solution, a neutralizing solution, a potassium permanganate solution for desmearing (cleaning), and a swelling solution, and has excellent stability against various processes using these solutions. EXAMPLES

[0194] The present invention will be described in more detail below with reference to preparation examples, examples, and comparative examples. The present invention is not limited to the preparation examples, examples, and comparative examples. The specific numerical values ​​of the blending ratio (content ratio), physical property values, parameters, etc. used in the following description can be replaced with the upper limit (numeric value defined as "less than or equal to" or "less than") or lower limit (numeric value defined as "more than or equal to" or "exceeding") of the corresponding blending ratio (content ratio), physical property values, parameters, etc. described in the above "Form for carrying out the invention".

[0195] Preparation Example 1 (Preparation of Binder) A binder was prepared by mixing 24.5 parts by mass of epoxy resin (base resin), 24.5 parts by mass of phenolic resin (curing agent), 1 part by mass of imidazole compound (curing accelerator), and 50 parts by mass of acrylic resin (thermoplastic resin).

[0196] Comparative Example 1 First, the first wiring 2 and the second wiring 3 were prepared. The diameter L1 of each of the first wiring 2 and the second wiring 3 was 260 μm. Additionally, the first magnetic sheet 25, the second magnetic sheet 26, and the third magnetic sheet 27 were produced so as to have the types and filling rates of magnetic particles listed in Table 1.

[0197] 2A, the second magnetic sheet 26, one of the first magnetic sheets 25, the first wiring 2 and the second wiring 3, the other first magnetic sheet 25, and the third magnetic sheet 27 were then arranged in this order toward the other side in the thickness direction. The distance L between the first wiring 2 and the second wiring 3 was 240 μm.

[0198] 2B, these were then hot pressed to form the first magnetic layer 4, the second magnetic layer 5, and the third magnetic layer 6. In this way, the inductor 1 not including the suppression section 7 was manufactured.

[0199] Example 1 As shown in FIGS. 2C and 3, a slit 21 having a length (width) L3 of 60 μm was formed in the second magnetic layer 5 of the inductor 1 of Comparative Example 1 using a dicing saw .

[0200] In this way, the inductor 1 including the suppression portion 7 having the slit 21 was manufactured.

[0201] Example 2 1 and 2C, an inductor 1 was manufactured in the same manner as in Example 1, except that a second slit 22 having a length (width) L5 of 60 μm was further formed in the third magnetic layer 6. The suppression section 7 has a slit 21 and a second slit 22.

[0202] Example 3 As shown in Figure 13, an inductor 1 including a suppression section 7 having a first filling section 37 and a second filling section 38 was manufactured in the same manner as in Example 1, except that a first filling section 37 and a second filling section 38 were embedded in the second magnetic layer 5 and the third magnetic layer 6, respectively, instead of the slit 21 and the second slit 22, respectively.

[0203] The first filling portion 37 and the second filling portion 38 were each made of a room temperature solid polyimide resin and had a relative permeability of 1. Before being embedded in the second magnetic layer 5 and the third magnetic layer 6, the first filling portion 37 and the second filling portion 38 each had a rectangular shape in cross section.

[0204] Example 4 As shown in FIG. 7, an inductor 1 was manufactured in the same manner as in Example 2, except that an intermediate slit 29 communicating with the slit 21 and the second slit 22 was formed in the suppressing portion 7.

[0205] Comparative Example 2 and Examples 5 to 8 Inductors 1 of Comparative Example 2 and Examples 5 to 8 were manufactured in the same manner as Comparative Example 1 and Examples 1 to 4, as shown in Table 2, except that spherical magnetic particles were used instead of the flat magnetic particles contained in the second magnetic sheet 26 and the third magnetic sheet 27.

[0206] <Evaluation> The following items were evaluated, and the results are shown in Tables 3 and 4.

[0207] <Crosstalk> The coupling coefficient between the first wiring 2 and the second wiring 3 of the inductor 1 in each example was measured. In addition, as a reference, the coupling coefficient between the first wiring 2 and the second wiring 3 of the inductor 1 in Comparative Example 1 was also measured. Next, crosstalk was evaluated according to the following criteria. Note that an impedance analyzer (manufactured by Agilent, "4291B") was used for the measurements.

[0208] [standard] ⊚: The coupling coefficient was reduced by 40% or more compared to Comparative Example 1 or Comparative Example 2. ◯: The binding coefficient was reduced by 20% or more and less than 40% compared to Comparative Example 1 or Comparative Example 2.

[0209] <Inductance> The mutual inductance between the first wiring 2 and the second wiring 3 of the inductor 1 in each example was measured. The inductance was evaluated according to the following criteria. An impedance analyzer (manufactured by Agilent, "4291B") was used for the measurement. [standard] ◯: Compared with Comparative Example 1 or Comparative Example 2, the self-inductance was maintained at 70% or more. △: The self-inductance was maintained at 50% or more and less than 70% of that of Comparative Example 1 or Comparative Example 2.

[0210] <DC superposition characteristics> The inductance reduction rate of the inductor 1 in each example was measured to evaluate the DC superposition characteristics. The inductance reduction rate was measured using an impedance analyzer (manufactured by Kuwaki Electronics, "65120B"). The inductance reduction rate was evaluated according to the following criteria. [Inductance when no DC bias current is applied - Inductance when a DC bias current of 10 A is applied] / [Inductance when a DC bias current of 10 A is applied] x 100 (%) [standard] ◯: The rate of decrease in inductance compared to Comparative Example 1 or Comparative Example 2 was 50% or less. ×: The rate of decrease in inductance compared to Comparative Example 1 or Comparative Example 2 was more than 50%.

[0211] [Table 1]

[0212] [Table 2]

[0213] [Table 3]

[0214] [Table 4] [Explanation of symbols]

[0215] 1 Inductor 2 1st wiring 3 2nd wiring 4 First magnetic layer 5 Second magnetic layer 6 Third magnetic layer 7 Suppression part 10 Inner surface 11 Page 1 12 Side 2 13 Page 3 14 Side 4 17 Outer surface 21 Slit 22 Second Slit 35 void 37 First filling section 38 Second filling section 71 Processing stable layer 72 2nd processing stable layer L2 Length of the slit in the thickness direction L3 Length of the slit in the adjacent direction L4 Length of the second slit in the thickness direction L5 Length of the second slit in the adjacent direction

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 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 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; a second magnetic layer disposed on the first surface; a third magnetic layer disposed on the second surface, the second magnetic layer has a third surface disposed opposite to the first surface with an interval in the thickness direction; the second magnetic layer and the third magnetic layer each have a higher relative permeability than the first magnetic layer; a suppression section that is located between the first wiring and the second wiring when projected in the thickness direction and is configured to suppress magnetic coupling between the first wiring and the second wiring, An inductor, wherein the suppression portion includes a first suppression portion located between the first surface and the third surface.

2. The inductor according to claim 1 , wherein the first suppression portion faces the first surface.

3. The inductor according to claim 1 , wherein the first suppression portion is exposed from the third surface.

4. An inductor as described in any one of claims 1 to 3, characterized in that the length of the first suppression portion in the thickness direction is longer than the length of the first suppression portion in the adjacent direction in which the first wiring and the second wiring are adjacent to each other.

5. 5. The inductor according to claim 1, wherein the first suppression portion is a slit formed in the second magnetic layer.

6. the first suppression portion is a first filling portion that is filled into a gap formed in the second magnetic layer, The relative permeability of the first filling portion is lower than the relative permeability of the first magnetic layer. The inductor according to any one of claims 1 to 4.

7. The inductor according to claim 1 , further comprising a process stabilizing layer disposed on the third surface of the second magnetic layer.

8. the third magnetic layer has a fourth surface disposed opposite to the second surface with an interval therebetween in the thickness direction, The inductor according to claim 1 , wherein the suppression portion further includes a second suppression portion located between the second surface and the fourth surface.

9. The inductor according to claim 8 , wherein the second suppression portion faces the second surface.

10. The inductor according to claim 8 or 9, wherein the second suppression portion is exposed from the fourth surface.

11. An inductor as described in any one of claims 8 to 10, characterized in that the length of the second suppression portion in the thickness direction is longer than the length of the second suppression portion in the adjacent direction in which the first wiring and the second wiring are adjacent to each other.

12. 12. The inductor according to claim 8, wherein the second suppression portion is a second slit formed in the third magnetic layer.

13. the second suppression portion is a second filling portion that is filled into a gap formed in the third magnetic layer, The relative permeability of the second filling portion is lower than the relative permeability of the first magnetic layer. An inductor according to any one of claims 8 to 11.

14. The inductor according to any one of claims 8 to 13, further comprising a second process stability layer disposed on the fourth surface of the third magnetic layer.

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