Method of manufacturing an inductor

Abstract

A method for manufacturing an inductor (1) includes a first step of preparing a hot press device (2) and a second step. The hot press device (2) includes a first mold (3), a second mold (4) spaced apart from the first mold (3) and smaller than the first mold (3), an inner frame member (5) surrounding a periphery of the second mold (4) and spaced apart from the first mold (3) in a pressing direction, the inner frame member (5) being movable relative to the second mold (4) in the pressing direction, and a flowable soft sheet (6) disposed on a second pressing surface (62) of the second mold (4). In the second step, a magnetic sheet (8) containing magnetic particles and a thermosetting resin and a plurality of wirings (9) spaced apart from each other are hot-pressed by the hot press device (2).

Description

Technical Field

[0001] This invention relates to a method for manufacturing an inductor. Background Technology

[0002] Previously, a method was proposed as follows: stacking other ferrite blanks on a ferrite blank containing multiple conductors, and firing them to manufacture an inductor comprising multiple conductors and a magnetic layer covering the multiple conductors (see, for example, Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 10-144526 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] However, in the method described in Patent Document 1, there is a situation where the magnetic layer near the opposite surface (side surface) of one conductor does not contact the opposite surface, but forms a gap defined by the opposite surface. Furthermore, there is a situation where the magnetic layer near the opposite surface of other conductors also forms the same gap. In these cases, there is a drawback: a decrease in the inductance of the inductor.

[0008] Therefore, in order to form a magnetic layer without the aforementioned gaps, an attempt was made to use a flatbed press to apply pressure to the ferrite billet.

[0009] However, during the application of pressure using a flatbed press, the ferrite blank sheet located between adjacent conductors applies pressure to the conductors outward (in a direction orthogonal to the thickness direction), causing the conductors to move outward (expand outward). Therefore, the distance between the conductors in the inductor is longer than the pre-designed distance. Consequently, such an inductor cannot achieve the desired inductance. Furthermore, even when attempting to establish an electrical connection between an external device and the conductor, through-holes are formed from the upper surface of the magnetic layer in the inductor towards the upper surface of the conductor, and conductive components are filled into the through-holes. Even so, the conductors are not exposed in these through-holes, thus making it impossible to implement the aforementioned connection.

[0010] The present invention provides a method for manufacturing an inductor capable of suppressing the formation of gaps in the magnetic layer between adjacent wirings and suppressing variations in the distance between adjacent conductors.

[0011] Solution for solving the problem

[0012] The present invention (1) includes a method for manufacturing an inductor, wherein the method comprises: a first step, wherein a hot pressing apparatus is prepared, the hot pressing apparatus comprising: a first mold; a second mold spaced apart from the first mold in a pressing direction and smaller than the first mold; a frame member surrounding the second mold and spaced apart from the first mold in the pressing direction, the frame member being movable relative to the second mold in the pressing direction; and a flowable flexible sheet disposed on a pressing surface of the second mold facing the first mold; and a second step, wherein the inductor is manufactured by using the hot pressing apparatus to press a material containing magnetic particles and a thermosetting resin that is more flowable than the first mold. A small magnetic sheet and a plurality of spaced wires are hot-pressed to manufacture an inductor comprising the plurality of wires and a magnetic layer containing the magnetic particles and a cured body of the thermosetting resin. The magnetic layer covers the plurality of wires in a manner that spans across the adjacent wires. The second step includes: a third step in which the magnetic sheet and the plurality of wires are placed such that they overlap with the flowable flexible sheet when projected along the pressure direction; a fifth step in which the frame member is pressed against the first mold; and a sixth step in which the second mold is brought close to the first mold, and the magnetic sheet and the plurality of wires are hot-pressed through the flowable flexible sheet and the release sheet.

[0013] In this manufacturing method, a magnetic sheet and multiple wirings are hot-pressed together with a flexible sheet larger than the magnetic sheet. This allows the flexible sheet to suppress outward flow of the magnetic sheet's peripheral surface.

[0014] Furthermore, it can suppress the formation of gaps in the magnetic layer while the magnetic sheet is filling the gaps between adjacent wirings. Therefore, it can suppress variations in the distance between adjacent wirings.

[0015] As a result, it is possible to manufacture inductors with the desired high inductance and excellent connection reliability when connected to external devices.

[0016] The present invention (2) includes a method for manufacturing an inductor as described in (1), wherein the hot pressing apparatus further includes the pressure-reducing space forming member, the pressure-reducing space forming member surrounding the frame member and spaced apart from the first mold, the pressure-reducing space forming member being able to contact the first mold, and a fourth step is included after the third step and before the fifth step, in which the pressure-reducing space forming member is brought into contact with the first mold to form a pressure-reducing space.

[0017] Using this manufacturing method, a depressurization space is formed in step 4. In step 5, the frame members inside the depressurization space are pressed against the first mold to form a sealed space with a depressurized atmosphere. Subsequently, in step 6, the magnetic sheet can be hot-pressed under a depressurized atmosphere. Therefore, the formation of gaps in the magnetic layer can be further effectively suppressed.

[0018] The present invention (3) includes a method for manufacturing an inductor as described in (1) or (2), wherein the release sheet comprises a buffer film.

[0019] Using this manufacturing method, in step 6, a buffer film can be used to bend one side of the magnetic sheet in the thickness direction along the circumference of the multiple wirings. In this way, when current flows through the multiple wirings in the inductor and a magnetic field is generated along the circumference of the multiple wirings, the inductance of the inductor can be increased by using the magnetic sheet with the above shape.

[0020] The present invention (4) includes a method for manufacturing an inductor according to any one of (1) to (3), wherein the magnetic sheet includes a first magnetic sheet and a second magnetic sheet, and the second step includes: a step of manufacturing an inductor precursor, wherein the first magnetic sheet is hot-pressed using the hot-pressing apparatus to manufacture an inductor precursor including a first magnetic layer, the first magnetic layer spanning between adjacent wirings and exposing one end face of the wirings in the thickness direction; and a step of forming a magnetic layer, wherein the inductor precursor and the second magnetic sheet are hot-pressed using the hot-pressing apparatus to form a magnetic layer covering the entire circumference of the wirings.

[0021] In this manufacturing method, an inductor precursor is fabricated, and then a second magnetic sheet is disposed relative to the inductor precursor. Thus, firstly, an inductor precursor with sufficiently suppressed gap formation is reliably fabricated, and then the second magnetic sheet can be further disposed on the inductor precursor and hot-pressed onto it, thereby enabling the manufacture of an inductor with even more sufficiently suppressed gap formation.

[0022] The effects of the invention

[0023] The inductor manufacturing method of the present invention can produce an inductor with a desired high inductance and excellent connection reliability when connected to external devices. Attached Figure Description

[0024] [ Figure 1 ] Figure 1 This refers to the first step of preparing a hot pressing device in one embodiment of the inductor manufacturing method of the present invention.

[0025] [ Figure 2 ] Figure 2 Continuing from Figure 1This indicates a third step in the manufacturing method of the inductor of the present invention, in which a magnetic sheet and a plurality of wires are placed in a hot pressing apparatus.

[0026] [ Figure 3 ] Figure 3 Continuing from Figure 2 This refers to a fourth step in one embodiment of the inductor manufacturing method of the present invention, in which an outer frame member is sealed to a first mold to form a first sealed space, and then the first sealed space is depressurized to form a depressurized space.

[0027] [ Figure 4 ] Figure 4 Continuing from Figure 3 This refers to the fifth step in one embodiment of the inductor manufacturing method of the present invention, in which the inner frame member is pressed against the first mold to form a second sealed space with a reduced pressure atmosphere.

[0028] [ Figure 5 ] Figure 5 Continuing from Figure 4 This refers to the sixth step in one embodiment of the inductor manufacturing method of the present invention, which involves hot-pressing a magnetic sheet and a plurality of wirings.

[0029] [ Figure 6 ] Figure 6 Indicates from Figure 5 The process of forming through holes from inductors removed by the hot pressing device.

[0030] [ Figure 7 ] Figure 7 In the first embodiment of manufacturing an inductor after manufacturing an inductor precursor, the third step involves arranging the first magnetic sheet and multiple wirings in a hot pressing apparatus.

[0031] [ Figure 8 ] Figure 8 It is a continuation of Figure 7 The sixth step involves hot-pressing the first magnetic sheet and multiple wirings to manufacture the inductor precursor.

[0032] [ Figure 9 ] Figure 9 It is a continuation of Figure 8 The inductor precursor and the second magnetic sheet are arranged in the third step of the hot pressing device.

[0033] [ Figure 10 ] Figure 10 The sixth step is to manufacture an inductor by hot pressing the second magnetic sheet and the inductor precursor.

[0034] [ Figure 11 ] Figure 11 In the second embodiment of manufacturing an inductor without manufacturing an inductor precursor, the third step involves arranging the first magnetic sheet and multiple wirings in a hot pressing apparatus.

[0035] [ Figure 12 ] Figure 12 It is a continuation of Figure 11 The sixth step involves hot-pressing the first magnetic sheet using a hot-pressing device.

[0036] [ Figure 13 ] Figure 13 It is a continuation of Figure 12 The second magnetic sheet is further disposed in the third step of the hot pressing device.

[0037] [ Figure 14 ] Figure 14 It is a continuation of Figure 13 The sixth step involves hot-pressing the second magnetic sheet using a hot-pressing device.

[0038] [ Figure 15 ] Figure 15 A~ Figure 15 Figure I illustrates Embodiment 2, which corresponds to the second embodiment. Figure 15 A is the process of placing the first piece into the hot pressing device. Figure 15 B is the process of placing the second piece into the hot pressing device. Figure 15 C is the process of placing the third piece into the hot pressing device. Figure 15 D is the process of placing the fourth piece into the hot pressing device. Figure 15 E is the process of placing the fifth piece into the hot pressing device. Figure 15 F is the process of placing the 6th piece into the hot pressing device. Figure 15 G is the process of placing the 7th piece into the hot pressing device. Figure 15 H is the process of placing the 8th piece into the hot pressing device. Figure 15 Step 1 is the process of placing the 9th piece into the hot pressing device.

[0039] [ Figure 16 ] Figure 16 It is an inductor in the second embodiment that includes a magnetic layer formed from the first to the ninth sheet, and is a cross-sectional view of the inductor corresponding to Embodiment 2.

[0040] [ Figure 17 ] Figure 17 In the third embodiment of manufacturing an inductor without manufacturing an inductor precursor, the third step involves placing the first magnetic sheet and the second magnetic sheet together in a hot pressing apparatus.

[0041] [ Figure 18 ] Figure 18 It is a continuation of Figure 17 The sixth step involves hot pressing the first and second magnetic sheets.

[0042] [ Figure 19 ] Figure 19This is a third step in the third embodiment, which uses a first magnetic sheet and a second magnetic sheet comprising the first to ninth sheets to clamp multiple wires, and is a cross-sectional view corresponding to Embodiment 3. Detailed Implementation

[0043] <One implementation method>

[0044] Reference Figures 1-6 This invention describes one embodiment of the method for manufacturing the inductor.

[0045] The manufacturing method of the inductor 1 includes a first step of preparing the hot pressing device 2 (see reference). Figure 1 The second step involves hot-pressing the magnetic sheet 8 and multiple wirings 9 using a hot-pressing device 2 (see reference). Figure 5 ).

[0046] [Step 1]

[0047] like Figure 1 As shown, in the first step, the hot pressing device 2 is prepared.

[0048] The hot pressing device 2 is capable of pressing the magnetic sheet 8 and multiple wirings 9 (see reference). Figure 2 An isostatic pressing device that performs hot pressing (isostatic pressing) isotropically. The hot pressing device 2 includes a first mold 3, a second mold 4, an inner frame member 5 as an example of a frame member, an outer frame member 81 as an example of a pressure reduction space forming member, and a fluid flexible sheet 6.

[0049] Furthermore, in this embodiment, the hot pressing device 2 is configured such that the second mold 4 and the inner frame member 5 can approach and apply pressure relative to the first mold 3. Additionally, the hot pressing device 2 is configured such that the outer frame member 81 can approach and contact (close) the first mold 3. Furthermore, the first mold 3 remains stationary in the pressure application direction of the hot pressing device 2.

[0050] The first mold 3 has a generally plate-like shape. The first mold 3 has a first pressure surface 61 facing the second mold 4, which will be described later. The first pressure surface 61 extends in a direction orthogonal to the pressure direction (surface direction). The first pressure surface 61 is flat. Furthermore, the first mold 3 includes a heater (not shown).

[0051] The second mold 4 is spaced apart from the first mold 3 in the pressure direction during the first process. The second mold 4 is movable relative to the first mold 3 in the pressure direction. The second mold 4 has a generally plate shape smaller than the first mold 3. Specifically, the second mold 4 is included within the first mold 3 when projected in the pressure direction. More specifically, the second mold 4 overlaps with the central portion of the first mold 3 in the surface direction when projected in the pressure direction. The second mold 4 has a second pressure surface 62, which is an example of a pressure surface facing the central portion of the first pressure surface 61 of the first mold 3 in the surface direction. The second pressure surface 62 extends in the surface direction. The second pressure surface 62 is parallel to the first pressure surface 61. In addition, the second mold 4 includes a heater (not shown).

[0052] The inner frame member 5 surrounds the periphery of the second mold 4. Specifically, the inner frame member 5 surrounds the entire periphery of the second mold 4, which is not shown in the figure. Furthermore, in the first step, the inner frame member 5 is spaced apart from the peripheral end of the first mold 3 in the pressure direction. That is, in the first step, the inner frame member 5 is arranged opposite to the peripheral end of the first mold 3 in the pressure direction, spaced apart. The inner frame member 5 integrally has a third pressure surface 28 facing the peripheral end of the first pressure surface 61 and an inner surface 29 facing inward. The inner frame member 5 is movable relative to both the first mold 3 and the second mold 4 in the pressure direction.

[0053] Furthermore, 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 fluid flexible sheet 6 (described below) from seeping between the inner frame member 5 and the second mold 4 during the relative movement of the inner frame member 5 and the second mold 4.

[0054] The outer frame member 81 surrounds the inner frame member 5. Specifically, the outer frame member 81 surrounds the entire circumference of the inner frame member 5, which is not shown in the figure. Furthermore, in the first step, the outer frame member 81 is spaced apart from the peripheral end of the first mold 3 in the pressure direction. That is, the outer frame member 81 is arranged opposite to the peripheral end of the first mold 3 in the pressure direction in the first step. The outer frame member 81 integrally has a contact surface 82 facing the peripheral end of the first pressure surface 61 and an inner cavity surface 83 facing inward. The outer frame member 81 is movable relative to both the first mold 3 and the inner frame member 5 in the pressure direction.

[0055] Additionally, the outer frame member 81 has an exhaust port 15. The upstream end of the exhaust port 15 faces the inner end of the inner side surface 83 of the cavity. The exhaust port 15 is connected to the vacuum pump 16 via an exhaust line 46. Furthermore, in the first step, the exhaust line 46 is sealed.

[0056] Additionally, 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 later) 45 from communicating with the outside during relative movement of the outer frame member 81 and the inner frame member 5.

[0057] The fluid flexible sheet 6 has a generally plate-like shape extending in a surface direction orthogonal to the pressure direction. The fluid flexible sheet 6 is disposed on the second pressure surface 62 of the second mold 4. Additionally, the fluid flexible sheet 6 is also disposed on the inner surface 29 of the inner frame member 5. More specifically, the fluid flexible sheet 6 contacts the entire surface of the second pressure surface 62 and the downstream portion of the inner surface 29 in the pressure direction. Furthermore, a sealing member (not shown) is provided between the fluid flexible sheet 6 and the inner surface 29 of the inner frame member 5. The inner frame member 5 is movable relative to the fluid flexible sheet 6 in the pressure direction.

[0058] The material used for the flowable soft sheet 6 is not particularly limited as long as it exhibits flowability and softness upon hot pressing; examples include gels or soft elastomers. The material for the flowable soft sheet 6 can be commercially available products, such as the αGEL series (manufactured by Taica Corporation) and the Riken Elastomers series (manufactured by Riken Technos Corporation). The thickness of the flowable soft sheet 6 is not particularly limited; 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, 1000 mm, preferably 100 mm.

[0059] The hot press apparatus 2 is described in detail in, for example, Japanese Patent Application Publication No. 2004-296746. Furthermore, commercially available products can be used for the hot press apparatus 2, such as the dry laminator series manufactured by Nikkiso Corporation.

[0060] [Step 2]

[0061] In the second process, such as Figure 5 As shown, the magnetic sheet 8 and multiple wirings 9 are hot-pressed using a hot-pressing device 2. Specifically, the second process includes a third, a fourth, a fifth, and a sixth process. In the second process, the third, fourth, fifth, and sixth processes are performed sequentially.

[0062] [Step 3]

[0063] like Figure 2 As shown, in the third step, firstly, the first demolding piece 14 is placed on the first pressure surface 61 of the first mold 3.

[0064] The first release piece 14 is smaller than the inner frame member 5 when projected along the thickness direction.

[0065] The first release sheet 14, for example, includes, in sequence, a first release film 11, a buffer film 12, and a second release film 13 on the downstream side of the pressure application direction. The materials of the first release film 11 and the second release film 13 can be appropriately selected according to the application and purpose; for example, polyesters such as polyethylene terephthalate (PET) and polyolefins such as polymethyl methacrylate (TPX) and polypropylene are examples. The thickness of the first release film 11 and the thickness of the second release film 13 are, for example, 1 μm or more, and also, for example, 1000 μm or less. The buffer film 12 includes a flexible layer. The flexible layer flows in both the planar and thickness directions during hot pressing in the second step. Examples of materials for the flexible layer include hot-flowing materials that flow in both the planar and pressure directions during hot pressing in the second step, described later. Hot-flowing materials may include, for example, olefin-(meth)acrylate copolymers (ethylene-(meth)acrylate copolymers, etc.) and olefin-vinyl acetate copolymers as main components. The thickness of the buffer film 12 is, for example, 50 μm or more, and also, for example, 500 μm or less. The buffer film 12 can use commercially available products, such as the OT series release film (manufactured by Sekisui Chemicals Co., Ltd.).

[0066] In addition, the first release sheet 14 may include either the first release film 11 and the second release film 13 as well as the buffer film 12, or it may only be the buffer film 12.

[0067] After the first release sheet 14 is placed on the first mold 3, the magnetic sheet 8 and a plurality of wires 9 are placed between the first release sheet 14 and the second release sheet 7 in such a way that they overlap with the fluid flexible sheet 6 when projected along the pressure direction.

[0068] Magnetic sheet 8 is used to form magnetic layer 30 in inductor 1 (see below). Figure 5 The magnetic sheet 8 is not yet the magnetic layer 30, and is not a fully cured body containing the thermosetting resin (described later), but specifically contains a B-order thermosetting resin.

[0069] The magnetic sheet 8 extends along a surface direction orthogonal to the thickness direction. The material of the magnetic sheet 8 is a magnetic composition containing magnetic particles and a thermosetting composition.

[0070] Examples of magnetic materials constituting magnetic particles include soft magnetic materials and hard magnetic materials. Soft magnetic materials are preferred from the viewpoint of inductance.

[0071] As soft magnetic materials, examples include single metallic bodies containing one metallic element in their pure state, such as eutectic mixtures (mixtures) of one or more metallic elements (first metallic element) and one or more metallic elements (second metallic element) and / or non-metallic elements (carbon, nitrogen, silicon, phosphorus, etc.), i.e., alloys. They can be used alone or in combination.

[0072] As a single metallic substance, an example is a metallic element composed of only one metallic element (the first metallic element). The first metallic element is appropriately selected from, for example, iron (Fe), cobalt (Co), nickel (Ni), and other metallic elements that can serve as the first metallic element in a soft magnetic body.

[0073] Furthermore, examples of single-metal bodies include those having a core containing only one metal element and a surface layer comprising partially or entirely inorganic and / or organic matter that modifies the surface of the core; organometallic compounds containing the first metal element; and forms resulting from the decomposition (thermal decomposition, etc.) of inorganic metal compounds. More specifically, examples of the latter include iron powder (sometimes called carbonyl iron powder) resulting from the thermal decomposition of an organoiron compound (specifically, carbonyl iron) containing iron as the first metal element. Furthermore, the location of the layer containing inorganic and / or organic matter that modifies the portion containing only one metal element is not limited to the surface described above. Moreover, there are no particular limitations on the organometallic compounds or inorganic metal compounds from which single-metal bodies can be obtained; appropriate selections can be made from known or conventional organometallic compounds or inorganic metal compounds that can produce single-metal bodies with soft magnetic properties.

[0074] The alloy body is a eutectic of one or more metallic elements (first metallic element) and one or more metallic elements (second metallic element) and / or non-metallic elements (carbon, nitrogen, silicon, phosphorus, etc.), and there are no particular restrictions as long as it can be used as an alloy body for soft magnetic materials.

[0075] The first metallic element is an essential element in the alloy, such as iron (Fe), cobalt (Co), and nickel (Ni). Furthermore, if the first metallic element is Fe, the alloy is an Fe-based alloy; if the first metallic element is Co, the alloy is a Co-based alloy; and if the first metallic element is Ni, the alloy is a Ni-based alloy.

[0076] The second metallic element is a minor component (secondary element) in the alloy and is compatible (eutectic) with the first metallic element. Examples include iron (Fe) (when the first metallic element is not Fe), cobalt (Co) (when the first metallic element is not Co), nickel (Ni) (when the first metallic element is not Ni), chromium (Cr), aluminum (Al), silicon (Si), copper (Cu), silver (Ag), manganese (Mn), calcium (Ca), barium (Ba), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), molybdenum (Mo), tungsten (W), ruthenium (Ru), rhodium (Rh), zinc (Zn), gallium (Ga), indium (In), germanium (Ge), tin (Sn), lead (Pb), scandium (Sc), yttrium (Y), strontium (Sr), and various rare earth elements. These elements can be used alone or in combination with two or more.

[0077] Nonmetallic elements are minor components (secondary elements) in an alloy and are compatible (eutectic) with the primary metallic element. Examples include boron (B), carbon (C), nitrogen (N), silicon (Si), phosphorus (P), and sulfur (S). They can be used alone or in combination with two or more elements.

[0078] Examples of Fe-based alloys as alloy bodies include magnetic stainless steel (Fe-Cr-Al-Si alloy) (including electromagnetic stainless steel), iron-silicon-aluminum alloy (Fe-Si-Al alloy) (including super iron-silicon-aluminum alloy), permalloy (Fe-Ni alloy), Fe-Ni-Mo alloy, Fe-Ni-Mo-Cu alloy, Fe-Ni-Co alloy, Fe-Cr alloy, Fe-Cr-Al alloy, Fe-Ni-Cr alloy, Fe-Ni-Cr-Si alloy, copper-silicon alloy (Fe-Cu-Si alloy), Fe-Si alloy, Fe-Si-B (-Cu-Nb) alloy, Fe-B- Si-Cr alloys, Fe-Si-Cr-Ni alloys, Fe-Si-Cr alloys, Fe-Si-Al-Ni-Cr alloys, Fe-Ni-Si-Co alloys, Fe-N alloys, Fe-C alloys, Fe-B alloys, Fe-P alloys, ferrites (including stainless steel ferrites, as well as soft magnetic ferrites such as Mn-Mg ferrites, Mn-Zn ferrites, Ni-Zn ferrites, Ni-Zn-Cu ferrites, Cu-Zn ferrites, and Cu-Mg-Zn ferrites), Permingt iron-cobalt high permeability alloys (Fe-Co alloys), Fe-Co-V alloys, Fe-based amorphous alloys, etc.

[0079] Examples of Co-based alloys include Co-Ta-Zr and cobalt (Co)-based amorphous alloys.

[0080] Examples of Ni-based alloys include, for instance, Ni-Cr alloys.

[0081] The shape of the magnetic particles is not particularly limited. Examples of anisotropic shapes include roughly flat (plate-shaped) and roughly needle-shaped (including roughly spindle (rugby ball) shapes), as well as roughly spherical, roughly granular, and roughly block-shaped shapes.

[0082] 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 60.

[0083] The volume percentage (filling rate) of magnetic particles in the magnetic composition is, for example, 10% or more, or, for example, 90% or less.

[0084] Examples of thermosetting resins include epoxy resins, melamine resins, thermosetting polyimide resins, unsaturated polyester resins, polyurethane resins, and silicone resins. From the viewpoint of adhesion and heat resistance, epoxy resins are preferred.

[0085] When the thermosetting resin contains epoxy resin, the thermosetting resin can also be formulated as an epoxy resin composition containing epoxy resin (such as cresol varnish-type epoxy resin), curing agent (such as phenolic resin), and curing accelerator (such as imidazole compound) in appropriate proportions. The amount of thermosetting resin relative to 100 volume parts of magnetic particles is, for example, 10 volume parts or more, and also, for example, 90 volume parts or less.

[0086] In addition to the aforementioned magnetic particles and thermosetting resin, the magnetic composition may also contain thermoplastic resins such as acrylic resin in appropriate proportions. Furthermore, the thermoplastic resin and the thermosetting resin together constitute a binder. The volume percentage of the binder in the magnetic composition is, for example, 10% or more, and also, for example, 90% or less.

[0087] The detailed formulation of the above magnetic composition is described in Japanese Patent Application Publication No. 2014-165363, etc.

[0088] Furthermore, the aforementioned thermosetting resin is of type B (semi-cured). Therefore, the magnetic sheet 8 is, for example, modulated as a type B sheet.

[0089] Multiple wires 9 are spaced apart from each other in a direction orthogonal to the length direction of the wires 9 and the thickness direction of the magnetic sheet 8 (adjacent directions). Each wire 9 of the multiple wires 9 has, for example, a generally circular shape in cross-section. Each wire 9 of the multiple wires 9 includes a conductor 91 and an insulating layer 92 covering the conductor 91.

[0090] The conductor 91 has a generally circular shape in cross-section, sharing a central axis with the wiring 9. The material of the conductor 91 is a metallic conductor such as copper. The lower limit of the radius of the conductor 91 is, for example, 25 μm, and the upper limit is, for example, 2000 μm.

[0091] The insulation layer 92 covers the entire circumference of the conductor 91. The insulation layer 92 has a generally annular shape in cross-section, sharing a central axis with the wiring 9. Examples of materials used for the insulation layer 92 include insulating resins such as polyester, polyurethane, polyesterimide, polyamideimide, and polyimide. The insulation layer 92 can be a single layer or multiple layers. The lower limit of the thickness of the insulation layer 92 is, for example, 1 μm, and the upper limit is, for example, 100 μm.

[0092] The radius of each of the plurality of wirings 9 is the sum of the radius of the conductor 91 and the thickness of the insulation layer 92. Specifically, its lower limit is, for example, 25 μm, preferably 50 μm, and its upper limit is, for example, 2000 μm, preferably 200 μm.

[0093] The lower limit of the distance (interval) L0 between adjacent wirings 9 can be appropriately set according to the use and purpose of the inductor 1, for example, 10 μm, preferably 50 μm, and the upper limit is, for example, 10000 μm, preferably 5000 μm.

[0094] Then, the second release piece 7 is placed on multiple wiring 9.

[0095] The second release piece 7 has the same layer structure as the first release piece 14. For example, the second release piece 7 is smaller than the inner frame member 5 when projected along the thickness direction.

[0096] In this third step, the first release piece 14, the magnetic piece 8, the plurality of wires 9, and the second release piece 7 are sequentially arranged on the first pressure surface 61 of the first mold 3. Alternatively, a sandwich structure formed by the first release piece 14 and the second release piece 7 holding the magnetic piece 8 and the plurality of wires 9 is arranged on the first mold 3.

[0097] [Step 4]

[0098] In the fourth process, such as Figure 2 arrows and Figure 3 As shown, the outer frame component 81 is brought into contact with the first mold 3 to form a decompression space 85.

[0099] Specifically, the outer frame member 81 is pressed against the periphery of the first pressing surface 61 of the first mold 3. As a result, the contact surface 82 of the outer frame member 81 and the periphery of the first pressing surface 61 of the first mold 3 are in close contact (closed) (preferably under pressure).

[0100] The decompression space 85 is defined by the inner side surface 83 of the outer frame member 81, the third pressure surface 28 and inner side surface 29 of the inner frame member 5, the second pressure surface 62, and the first pressure surface 61 of the first mold 3. Furthermore, the inner side surface 83 that defines the decompression space 85, together with the first mold 3, constitutes a chamber device.

[0101] The pressure of the outer frame member 81 relative to the first mold 3 is set to a degree that ensures the airtightness (non-communication with the outside) of the decompression space 85 described later through the tight seal between the contact surface 82 and the first pressure surface 61, specifically, 0.1 MPa or more and 20 MPa or less.

[0102] Thus, a first sealed space 84 is formed between the first mold 3, the outer frame member 81, and the fluid flexible sheet 6. The first sealed space 84 is shielded from the outside. However, the exhaust pipe 46 is connected to the first sealed space 84.

[0103] On the other hand, the second release sheet 7 and the fluid soft sheet 6 are also spaced apart in the direction of pressure.

[0104] Next, in the fourth step, the first sealed space 84 is depressurized to form a depressurized space 85.

[0105] Specifically, the vacuum pump 16 is driven, which in turn opens the exhaust line 46. As a result, the first sealed space 84, which is connected to the exhaust port 15, is depressurized. Thus, the first sealed space 84 becomes a depressurization space 85.

[0106] The upper limit of the pressure in the pressure relief space 85 (or exhaust line 46) is, for example, 100,000 Pa, preferably 10,000 Pa, and the lower limit is 1 Pa.

[0107] [Step 5]

[0108] In the fifth process, such as Figure 3 arrows and Figure 4 As shown, the inner frame member 5 is pressed against the first mold 3 to form a second enclosed space 45, which is an example of an enclosed space.

[0109] Specifically, the inner frame member 5 is pressed against the periphery of the first pressing surface 61 of the first mold 3. As a result, the third pressing surface 28 of the inner frame member 5 and the periphery of the first pressing surface 61 of the first mold 3 are in close contact with each other.

[0110] The pressure of the inner frame member 5 relative to the first mold 3 is set to a degree that prevents the fluid soft sheet 6 in the sixth process described later from leaking to the outside through the tight seal between the third pressure surface 28 and the first pressure surface 61. Specifically, it is 0.1 MPa or more and 50 MPa or less.

[0111] Thus, a second sealed space 45 is formed on the inner side of the inner frame member 5, which is surrounded by the first mold 3 and the fluid flexible sheet 6 in the pressure direction. The communication between the second sealed space 45 and the exhaust pipe 46 is blocked by the inner frame member 5.

[0112] The second enclosed space 45 has the same decompression degree (air pressure) as the aforementioned decompression space 85.

[0113] In addition, the second release sheet 7 and the flowable soft sheet 6 are spaced apart in the direction of pressure application.

[0114] [Step 6]

[0115] like Figure 4 arrows and Figure 5 As shown, in the sixth step, the second mold 4 is brought close to the first mold 3, and the magnetic sheet 8 and multiple wires 9 are hot-pressed through the fluid flexible sheet 6, the second release sheet 7 and the first release sheet 14.

[0116] First, the heaters contained in the first mold 3 and the second mold 4 are heated. Then, the second mold 4 is moved in the direction of pressure application. As a result, the fluid flexible sheet 6 moves closer to the second release sheet 7.

[0117] Therefore, the fluid flexible sheet 6 softly contacts the entire surface of the upstream side of the second release sheet 7 in the pressure direction, except for the peripheral end. At this time, due to the fluidity and flexibility of the fluid flexible sheet 6, the fluid flexible sheet 6 deforms together with the second release sheet 7 along the shape of the plurality of lines 9. The fluid flexible sheet 6 and the second release sheet 7 are in close contact.

[0118] The second mold 4 is then hot-pressed toward the first mold 3.

[0119] The lower limit of the hot pressing 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 heating conditions are those that allow the thermosetting resin to fully cure. Specifically, 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.

[0120] Therefore, the magnetic sheet 8 and the plurality of wires 9 are pressed with equal pressure from both sides of the magnetic sheet 8 in the thickness direction and the surface direction. In short, the magnetic sheet 8 and the plurality of wires 9 are subjected to isostatic pressure.

[0121] Therefore, the magnetic sheet 8 flows to embed multiple wirings 9. Furthermore, the magnetic sheet 8 spans between adjacent wirings 9. Also, one and the other sides of the magnetic sheet 8 in the thickness direction are bent along the circumference of the multiple wirings 9.

[0122] Furthermore, the peripheral side surface 38 of the magnetic sheet 8 is pressed from the side (outer side) towards the inside by the fluid flexible sheet 6 and the second release sheet 7. Therefore, it is possible to suppress the outward flow of the peripheral side surface 38 of the magnetic sheet 8.

[0123] Furthermore, the flow of the aforementioned magnetic sheet 8 is caused by the heating of the heaters of the first mold 3 and the second mold 4, resulting in the flow of the B-order thermosetting resin and the flow of the thermoplastic resin that needs to be formulated.

[0124] Through further heating by the aforementioned heater, the thermosetting resin becomes C-order. That is, a magnetic layer 30 is formed, which contains magnetic particles and a cured body (C-order body) of thermosetting resin.

[0125] Thus, an inductor 1 is manufactured, comprising a plurality of wirings 9 and a magnetic layer 30 covering the plurality of wirings 9 in a manner that spans across the adjacent wirings 9.

[0126] like Figure 6 As shown, the inductor 1 is then removed from the self-heating pressing device 2. Next, the inductor 1 is shaped. For example, a through hole 47 is formed at the portion of the magnetic layer 30 corresponding to the end of the wiring 9 along its length. Specifically, the through hole 47 is formed by removing the corresponding magnetic layer 30 and insulating layer 92 using a laser, a perforating machine, or the like. The through hole 47 exposes one side of the conductor 91 in the thickness direction (thickness direction of the magnetic layer 30).

[0127] Then, a conductive component (not shown) is disposed in the through-hole 47, and the external device and the wire 91 are electrically connected by means of the conductive component and conductive connecting materials such as solder, solder paste, and silver paste. The conductive component includes a plating layer.

[0128] Subsequently, as needed, the conductive components and conductive connecting materials are reflow soldered during the reflow soldering process.

[0129] [Effects of one implementation method]

[0130] Furthermore, in the manufacturing method of this inductor 1, the magnetic sheet 8 and the plurality of wirings 9 are isotropically hot-pressed (isostatically pressed) through a flexible sheet 6 that is larger than the magnetic sheet 8 using a hot-pressing device 2. Thus, the flexible sheet 6 can be used to suppress the outward flow of the peripheral side surface 38 of the magnetic sheet 8.

[0131] Furthermore, it is possible to suppress the formation of gaps in the magnetic layer 30 while the magnetic sheet 8 is filling the gaps between adjacent wirings 9. Therefore, it is possible to suppress variations in the distance between adjacent wirings 9.

[0132] As a result, it is possible to manufacture an inductor 1 with the desired high inductance and excellent connection reliability when connected to external devices.

[0133] In addition, using this manufacturing method, such as Figure 3 As shown, in the fourth step, a decompression space 85 is formed, as... Figure 4 As shown, in the fifth step, the inner frame member 5 on the inner side of the outer frame member 81 is pressed against the first mold 3, which can form a second sealed space 45 under reduced pressure. Then, in the sixth step, the magnetic sheet 8 can be hot-pressed under reduced pressure, thus further effectively suppressing the formation of gaps in the magnetic layer 30. For example, foaming can be suppressed in the subsequent reflow soldering process.

[0134]

[0135] In the following variations, the same reference numerals are used for components and processes identical to those in the first embodiment, and detailed descriptions are omitted. Furthermore, in the variations, unless otherwise specified, the same effects as in the first embodiment can be achieved. Moreover, a first embodiment and its variations can be appropriately combined.

[0136] In a modified example, the second release sheet 7 and / or the first release sheet 14 do not include the buffer film 12.

[0137] Preferably, as in one embodiment, both the second release sheet 7 and the first release sheet 14 include a buffer film 12. In another embodiment, as... Figure 5 As shown, in the sixth step, the buffer film 12 contained in the first release sheet 14 and the second release sheet 7 (see reference) can be utilized. Figure 1 and Figure 2 One side and the other side of the magnetic sheet 8 in the thickness direction are bent along the circumference of the plurality of wires 9. In this way, when current flows through the plurality of wires 9 in the inductor 1 and a magnetic field is generated along the circumference of the plurality of wires 9, the inductance of the inductor 1 can be increased by using the magnetic sheet 8 having the above shape.

[0138] In addition, in the modified example, the first demolding piece 14 is not configured relative to the first mold 3.

[0139] On the other hand, preferably, as in one embodiment, the first release tab 14 is disposed relative to the first mold 3. This prevents the magnetic layer 30 in the inductor 1 from adhering to the first pressure surface 61 of the first mold 3 or from generating residual adhesive (contamination).

[0140] like Figure 2 As shown by the imaginary line, the size of the first release piece 14 can be changed to a size that is opposite to the outer frame member 81 in the thickness direction. In the fourth step of this modified example, the outer frame member 81 is brought into contact with the peripheral end of the first release piece 14 (preferably under pressure) to form a first sealed space 84, then a depressurization space 85 is formed, and then the inner frame member 5 is pressed against the peripheral end of the first release piece 14 to form a second sealed space 45 under a depressurized atmosphere.

[0141] In addition, in the modified example, the second release piece 7 is not provided.

[0142] On the other hand, preferably, as in one embodiment, the second release sheet 7 is arranged relative to the plurality of wirings 9. This prevents the magnetic layer 30 in the inductor 1 from adhering to the flexible sheet 6 or from generating residual adhesive (contamination).

[0143] For example, each of the multiple wirings 9 may have a shape that is approximately rectangular in cross-section or a shape that is approximately polygonal in cross-section, as not illustrated.

[0144] Step 2 does not include Step 4. Step 2 includes Step 3, Step 5, and Step 6 in sequence. In Step 5, the inner frame member 5 is used to form a second sealed space 45 under normal pressure. In Step 6, pressure is applied to the magnetic sheet 8 and multiple wirings 9 under normal pressure.

[0145] Preferably, the second step includes a fourth step. The fourth step forms a depressurized space 85. In the fifth step, a second sealed space 45 under a depressurized atmosphere is formed. In the sixth step, pressure can be applied to the magnetic sheet 8 under a depressurized atmosphere, thus further effectively suppressing the formation of gaps in the magnetic layer 30 and suppressing foaming during the reflow soldering process.

[0146] <Embodiment 1 to Embodiment 3>

[0147] In the following embodiments, the same reference numerals are used for components and processes identical to those in the above embodiment, and detailed descriptions are omitted. Furthermore, in each embodiment, unless otherwise specified, the same effects as in the first embodiment can be achieved. Moreover, an embodiment, its variations, and other embodiments can be appropriately combined.

[0148] In one embodiment, one magnetic sheet 8 is hot-pressed, but it is also possible to hot-press multiple magnetic sheets 8 separately or to hot-press multiple magnetic sheets 8 together. Hereinafter, specific embodiments of these embodiments will be described sequentially from the first embodiment to the third embodiment.

[0149] [First Implementation]

[0150] like Figures 7-10 As shown, the first embodiment includes a process of hot-pressing the first magnetic sheet 21 and a plurality of wirings 9 to fabricate the inductor precursor 40 (see reference). Figure 8 The process of hot-pressing the inductor precursor 40 and the second magnetic sheet 22 (see reference). Figure 10 ).

[0151] To fabricate the inductor precursor 40, such as Figure 7 As shown, firstly, the first magnetic sheet 21 is placed on the upstream side of the first release sheet 14 in the pressure direction (corresponding to the third step of one embodiment).

[0152] The first magnetic sheet 21 is a preparatory sheet for forming the magnetic layer 30 together with the second magnetic sheet 22 described later. The first magnetic sheet 21 is also a segmented sheet formed by dividing the aforementioned magnetic sheet 8 in the thickness direction. The material of the first magnetic sheet 21 is the same magnetic composition as described above.

[0153] Furthermore, the magnetic composition of the first magnetic sheet 21 preferably contains magnetic particles having an isotropic shape, and more preferably contains magnetic particles having a generally flat shape.

[0154] In the first magnetic sheet 21, the lower limit of the volume ratio of the magnetic particles is, for example, 30% volume, preferably 45% volume, and the upper limit is, for example, 85% volume, preferably 75% volume.

[0155] If the volume ratio of the magnetic particles in the first magnetic sheet 21 is above the lower limit, then the first magnetic sheet 21 can ensure the desired relative permeability.

[0156] If the volume ratio of the magnetic particles in the first magnetic sheet 21 is below the aforementioned upper limit, the proportion of thermosetting resin (and thermoplastic resin) in the first magnetic sheet 21 can be increased. Therefore, the flowability of the first magnetic sheet 21 during hot pressing is improved, and the first magnetic sheet 21 flows smoothly between adjacent wirings 9, effectively suppressing the formation of the aforementioned gaps. Furthermore, when the first magnetic sheet 21 flows under hot pressing, the magnetic composition of the first magnetic sheet 21 smoothly wraps around the opposing surfaces 99 of adjacent wirings 9 (the surface between one end face 95 in the thickness direction and the other end face 96 in the thickness direction (described later), and the side facing the adjacent wiring 9). Therefore, the outward movement of adjacent wirings 9 can be effectively suppressed.

[0157] The lower limit of the thickness of the first magnetic sheet 21 is, for example, 10 μm, preferably 20 μm, and the upper limit is, for example, 2000 μm, preferably 1000 μm. The lower limit of the ratio of the thickness of the first magnetic sheet 21 to the radius of the wiring 9 is, for example, 0.01, preferably 0.1, and the upper limit is, for example, 2.0, preferably 1.5.

[0158] If the thickness and / or ratio of the first magnetic sheet 21 is above the aforementioned lower limit, the gap between adjacent wirings 9 can be reliably filled.

[0159] If the thickness of the first magnetic sheet 21 is below the aforementioned upper limit, the magnetic layer 30 can expose one end face 95 and the other end face 96 of the plurality of wirings 9 in the thickness direction.

[0160] The relative permeability of the first magnetic sheet 21 is not particularly limited and can be appropriately set according to the application and purpose of the inductor 1, for example, it can be 50 or less but greater than 1. Furthermore, the relative permeability of the first magnetic sheet 21 can be measured using an impedance analyzer at a frequency of 10 MHz. The relative permeability of the second magnetic sheet 22, described later, is the same as described above.

[0161] After that, as Figure 8 As shown, the fourth step of one implementation method is performed sequentially (refer to...). Figure 3 Step 5 (refer to) Figure 4 ) and the 6th process (refer to) Figure 8 In other words, the first sealed space 84 is depressurized to form a depressurization space 85 (see reference). Figure 3 After that, a second enclosed space 45 is formed (refer to...). Figure 4 After that, the first magnetic sheet 21 and the plurality of wirings 9 are hot-pressed (see reference). Figure 8 ).

[0162] In particular, when the first magnetic sheet 21 and the plurality of wires 9 are hot-pressed (applied isostatically) using the hot-pressing device 2, the first magnetic sheet 21 is wound around to the side of each of the plurality of wires 9, and then positioned between adjacent wires 9 and outside the outermost plurality of wires 9. Thus, the precursor magnetic layer 31 exposes one end face 95 and the other end face 96 of the plurality of wires 9 in the thickness direction of the first magnetic sheet 21. Furthermore, the one end face 95 and the other end face 96 in the thickness direction also contact the second release sheet 7 and the first release sheet 14, respectively.

[0163] One end face 95 in the thickness direction of the wiring 9 includes one end edge 97 in the thickness direction of the first magnetic sheet 21 on the circumferential surface of the wiring 9. The end face 95 in the thickness direction of the wiring 9 extends in two directions (clockwise and counterclockwise) in the circumferential direction, for example, by 60 degrees, preferably 45 degrees, and more preferably 30 degrees, based on the line segment connecting the end edge 97 and the center of the wiring 9. In other words, the end face 95 in the thickness direction of the wiring 9 extends in a circumferential direction of the wiring 9 (towards the magnetic field generated by the current flowing in the wiring 9), for example, by more than 30 degrees and less than 150 degrees, preferably more than 45 degrees and less than 135 degrees, and more preferably more than 60 degrees and less than 120 degrees, based on the line segment connecting adjacent wiring 9. Furthermore, the end edge 97 corresponds to the upstream side edge in the pressure direction on the circumferential surface of the wiring 9.

[0164] The other end face 96 in the thickness direction of the wiring 9 includes the other edge 98 in the thickness direction of the first magnetic sheet 21 on the circumferential surface of the wiring 9. The other end face 96 in the thickness direction of the wiring 9 is positioned relative to the line segment connecting the other edge 98 and the center of the wiring 9, advancing in two directions (clockwise and counterclockwise) in the circumferential direction, for example, by 60 degrees, preferably 45 degrees, and more preferably 30 degrees. In other words, the other end face 96 in the thickness direction of the wiring 9 is positioned relative to the line segment connecting adjacent wiring 9, advancing in another circumferential direction of the wiring 9 (towards the direction of the magnetic field generated by the current flowing in the wiring 9), for example, by 30 degrees or more but less than 150 degrees, preferably by 45 degrees or more but less than 135 degrees, and more preferably by 60 degrees or more but less than 120 degrees. Furthermore, the other edge 98 corresponds to the downstream edge in the pressure direction on the circumferential surface of the wiring 9. The center of the wiring 9 is located on the straight line connecting one edge 97 and the other edge 98.

[0165] By applying hot pressing (isostatic pressure) as described above, a precursor magnetic layer 31 is formed that spans between adjacent wirings 9, exposing (not covering) one end face 95 in the thickness direction and the other end face 96 in the thickness direction of the wirings 9. Furthermore, when projected along the adjacent directions of the plurality of wirings 9, the precursor magnetic layer 31 is entirely contained within the adjacent wirings 9. The precursor magnetic layer 31 includes a thin-walled portion 94 with the thinnest thickness at approximately the center between adjacent wirings 9. The lower limit of the ratio of the thickness of the thin-walled portion 94 to the radius of each of the plurality of wirings 9 is, for example, 0.1, preferably 0.2, and the upper limit is, for example, 1.5.

[0166] Thus, an inductor precursor 40 comprising a precursor magnetic layer 31 and multiple wirings 9 is produced.

[0167] Furthermore, the thermosetting resin of the precursor magnetic layer 31 of the inductor precursor 40 is of grade C.

[0168] Next, as Figure 9 As shown, the second magnetic sheet 22 and the inductor front body 40 are hot-pressed using the hot-pressing device 2.

[0169] Specifically, first, the inductor precursor 40 is removed from the hot-pressing device 2. Then, the second magnetic sheet 22 and the inductor precursor 40 are placed back into the hot-pressing device 2. Specifically, the two second magnetic sheets 22 are arranged on both sides of the inductor precursor 40 in the thickness direction (pressure direction).

[0170] The second magnetic sheet 22 is a preparatory sheet used to form the magnetic layer 30 together with the first magnetic sheet 21. The second magnetic sheet 22 is also a segmented sheet formed by dividing the aforementioned magnetic sheet 8 in the thickness direction.

[0171] The relative permeability of the second magnetic sheet 22 can be appropriately set according to the application and purpose of the inductor 1, with a lower limit of, for example, 15, preferably 20, and an upper limit of, for example, 200 or less, preferably 150, and more preferably 75.

[0172] The lower limit of the ratio of the relative permeability of the second magnetic sheet 22 to the relative permeability of the first magnetic sheet 21 is, for example, greater than 1, preferably 1.1, more preferably 1.5, and the upper limit is, for example, 3.

[0173] If the relative permeability and / or ratio of the first magnetic sheet 21 and the second magnetic sheet 22 are within the above range, the DC superposition characteristics of the inductor 1 can be improved.

[0174] Each of the two second magnetic sheets 22 is a single layer or multiple layers, preferably multiple layers. Specifically, as shown in the figure... Figure 9 As shown, each of the two second magnetic sheets 22 includes sheet 1 51, sheet 2 52, sheet 3 53, sheet 4 54, sheet 55, sheet 6 56, sheet 7 57, sheet 8 58 and sheet 9 59.

[0175] For the first piece 51 to the ninth piece 59, for example, the type, shape and volume ratio of the magnetic particles can be appropriately changed to satisfy the following formula (1).

[0176] μ1=μ2=μ3<μ4=μ5<μ6=μ7=μ8=μ9 (1)

[0177] In equation (1), μ1 to μ9 are as follows.

[0178] μ1: Relative permeability of the first 51-chip

[0179] μ2: Relative permeability of the second 52-element plate

[0180] μ3: Relative permeability of the third 53-cell plate

[0181] μ4: Relative permeability of the 4th piece of 54

[0182] μ5: Relative permeability of the 5th piece (μ5).

[0183] μ6: Relative permeability of the 6th piece of 56

[0184] μ7: Relative permeability of the 7th piece of 57

[0185] μ8: Relative permeability of the 8th piece of 58

[0186] μ9: Relative permeability of the 9th piece of 59

[0187] If the relative permeability of the first piece 51 to the ninth piece 59 satisfies the above formula (1), then the DC superposition characteristics of inductor 1 can be improved.

[0188] In order to make the relative permeability of the first piece 51 to the ninth piece 59 as described above, the formulation of the magnetic composition is appropriately set, and the first piece 51 to the ninth piece 59 are manufactured.

[0189] The above-mentioned pieces are formed from the above-mentioned magnetic composition into a plate shape extending along the surface direction.

[0190] Next, the inductor front body 40 is clamped by the two second magnetic plates 22 mentioned above.

[0191] For convenience, the piece disposed upstream of the pressure direction of the multiple wirings 9 is referred to as the "piece on one side", and the piece disposed downstream of the pressure direction of the multiple wirings 9 is referred to as the "piece on the other side". For example, the first piece 51 to the ninth piece 59 on one side and the first piece 51 to the ninth piece 59 on the other side are used to clamp the inductor front body 40.

[0192] A precursor laminate 41 comprising a second magnetic sheet 22 on one side, an inductor precursor 40, and a second magnetic sheet 22 precursor on the other side is fabricated.

[0193] Furthermore, the precursor laminate 41 can be prefabricated and placed in the hot press 2. For example, the precursor laminate 41 can be produced by temporarily bonding (temporarily attaching) (temporarily fixing) the second magnetic sheet 22 on one side and the second magnetic sheet 22 on the other side relative to the inductor precursor 40 using a flatbed press comprising two parallel flat plates. The conditions for parallel pressing are the heating temperature and heating time that allow the second magnetic sheet 22 and the inductor precursor 40 to bond (temporarily fix) together, even though the thermosetting resin has not been completely cured.

[0194] The aforementioned precursor laminate 41 is positioned between the first release sheet 14 and the second release sheet 7.

[0195] Subsequently, the fourth process is performed sequentially relative to the precursor laminate 41 (refer to...). Figure 3 Step 5 (refer to) Figure 4 ) and the 6th process (refer to) Figure 10 In other words, the first sealed space 84 is depressurized to form a depressurization space 85 (refer to...). Figure 3 ), which then forms the second enclosed space 45 (refer to) Figure 4 The precursor laminate 41 is hot-pressed (refer to...). Figure 10 ).

[0196] When hot pressing the first magnetic sheet 21 (refer to...) Figure 8 The first pressure P1 and the hot pressing of the precursor laminate 41 containing the second magnetic sheet 22 (refer to) Figure 10 The pressure P2 of the second test can be the same or different. Preferably, the pressure P2 of the second test is higher than the pressure P1 of the first test. Specifically, the lower limit of the ratio (P2 / P1) of the pressure P2 of the second test to the pressure P1 of the first test is, for example, 1.5, preferably 2, more preferably 2.5, and the upper limit is, for example, 25, preferably 15, more preferably 10.

[0197] If the ratio (P2 / P1) is above the lower limit mentioned above, gaps can be effectively suppressed between one end face 95 and the outer magnetic layer 37 in the thickness direction of the plurality of wirings 9 and between the other end face 96 and the outer magnetic layer 37 in the thickness direction of the plurality of wirings 9.

[0198] If the ratio (P2 / P1) is below the above upper limit, the widening of the spacing between adjacent wirings 9 can be effectively suppressed.

[0199] Thus, a magnetic layer 30 is formed.

[0200] Furthermore, the magnetic layer 30 includes an inner magnetic layer 36 and an outer magnetic layer 37, which will be described later. The inner magnetic layer 36 is formed from the first sheet 51 to the third sheet 53 of the first magnetic sheet 21 and the second magnetic sheet 22. The outer magnetic layer 37 is formed from the fourth sheet 54 to the ninth sheet 59 of the second magnetic sheet 22.

[0201] Through the above hot pressing, the region in the magnetic layer 30 corresponding to the second magnetic sheet 22 (the first sheet 51 to the ninth sheet 59) becomes the C-order.

[0202] Furthermore, in this method, firstly, an inductor precursor 40 that sufficiently suppresses the formation of gaps is reliably manufactured, and then the second magnetic sheet 22 is disposed on the inductor precursor 40 and hot-pressed thereon, thus enabling the manufacture of an inductor 1 that further sufficiently suppresses the formation of gaps.

[0203] [Modifications of the first embodiment]

[0204] In the following variations, the same reference numerals are used for components and processes identical to those in the first embodiment, and detailed descriptions are omitted. Furthermore, in these variations, unless otherwise specified, the same effects as in the first embodiment can be achieved. Moreover, an embodiment and its variations can be appropriately combined.

[0205] In a modified example, in the inductor precursor 40, the precursor magnetic layer 31 exposes only one end face 95 of the plurality of wirings 9 in the thickness direction, while covering the other end face 96 in the thickness direction.

[0206] [Second Embodiment to Third Embodiment]

[0207] In the second and third embodiments, the inductor precursor 40 is not manufactured, and multiple magnetic sheets 8 are arranged sequentially or together on multiple wirings 9 and then hot-pressed.

[0208] [Second Implementation]

[0209] In the second embodiment, such as Figures 11-13 As shown, a plurality of magnetic sheets 8 comprising two first magnetic sheets 21 and two second magnetic sheets 22 are prepared.

[0210] In the second embodiment, such as Figures 11-14 As shown, firstly, multiple wires 9 are clamped using two first magnetic sheets 21, and then they are hot-pressed using a hot pressing device 2. Afterward, they are clamped using two second magnetic sheets 22.

[0211] The first magnetic sheet 21 on one side and the second magnetic sheet 22 on the other side can be three or more sheets, for example, such as Figure 15 A~ Figure 15 As shown in Figure I, it may also include the first piece 51 to the ninth piece 59 on one side. The first magnetic piece 21 and the second magnetic piece 22 on the other side may also be three or more pieces, for example, it may also include the first piece 51 to the ninth piece 59 on the other side.

[0212] In the second embodiment, such as Figure 11 As shown, firstly, the first magnetic sheet 21 on the other side, the plurality of wirings 9, and the first magnetic sheet 21 on one side are arranged between the first release sheet 14 and the second release sheet 7 (third step). Next, as... Figure 12 As shown, steps 4 through 6 are performed sequentially to form an inner magnetic layer 36 of order C. This manufactures an inductor 1 comprising multiple wirings 9 and an inner magnetic layer 36 covering the multiple wirings 9 in a manner spanning between adjacent wirings 9.

[0213] Next, the inductor 1 is removed from the self-heating pressing device 2. Afterwards, as... Figure 13 As shown, the second magnetic sheet 22 on the other side, the inductor 1, and the second magnetic sheet 22 on one side are arranged between the first demolding sheet 14 and the second demolding sheet 7 (third step). Next, as... Figure 14 As shown, steps 4 through 6 are performed sequentially to hot-press them, forming the outer magnetic layer 37 of the C-order.

[0214] Thus, a magnetic layer 30 is formed, consisting of an inner magnetic layer 36 and an outer magnetic layer 37.

[0215] In addition, such as Figure 15 A~ Figure 16 As shown, in the case where the first magnetic sheet 21 and the second magnetic sheet 22 on one side include the first sheet 51 to the ninth sheet 59 on one side, and the first magnetic sheet 21 and the second magnetic sheet 22 on the other side include the first sheet 51 to the ninth sheet 59 on the other side, as Figure 15 As shown in A, firstly, in the hot pressing device 2, the first piece 51 on the other side, a plurality of wires 9 and the first piece 51 on one side are arranged sequentially on the upstream side facing the pressure direction (third step). Then, they are hot pressed to obtain the inductor 1 (fourth to sixth steps), and the inductor 1 is taken out from the hot pressing device 2.

[0216] Next, as Figure 15 As shown in Figure B, in the hot pressing apparatus 2, the second piece 52 on the other side, the inductor 1, and the second piece 52 on one side are sequentially arranged towards the upstream side in the pressure direction (step 3). Then, they are hot-pressed to obtain the inductor 1 (steps 4 to 6). The inductor 1 is then removed from the hot pressing apparatus 2. Afterwards, as... Figure 15 C~ Figure 15 As shown in H, the process is repeated using slices 3 through 9.

[0217] Therefore, as Figure 16 As shown, an inductor 1 is manufactured that includes a plurality of wirings 9 and a magnetic layer 30 covering the plurality of wirings 9 in a manner that spans across the plurality of adjacent wirings 9.

[0218] The magnetic layer 30 includes, for example, an inner magnetic layer 36 formed by the first sheet 51 to the third sheet 53 and an outer magnetic layer 37 formed by the fourth sheet 54 to the ninth sheet 59.

[0219] [Third Implementation]

[0220] In the third embodiment, such as Figure 17 and Figure 18 As shown, multiple magnetic sheets 8 are arranged together with multiple wiring 9, and they are hot-pressed together using a hot-pressing device 2.

[0221] like Figure 17As shown, for example, a laminate 48 is prepared, consisting of two first magnetic sheets 21 and two second magnetic sheets 22 holding multiple wirings 9.

[0222] More specifically, a second magnetic sheet 22 on one side, a first magnetic sheet 21 on one side, multiple wires 9, a first magnetic sheet 21 on the other side, and a second magnetic sheet 22 on the other side are arranged sequentially on the upstream side facing the direction of pressure. They are temporarily bonded together by a flatbed press to create a laminate 48.

[0223] like Figure 18 As shown, the laminate 48 is then hot-pressed using the hot pressing device 2.

[0224] Thus, the first magnetic sheet 21 and the second magnetic sheet 22 are upgraded to form an inner magnetic layer 36 and an outer magnetic layer 37, respectively. A magnetic layer 30 composed of the inner magnetic layer 36 and the outer magnetic layer 37 is formed.

[0225] Inner magnetic layer 36 is composed of Figure 19 The first piece 51 to the third piece 53 shown are formed. The outer magnetic layer 37 is composed of... Figure 19 The fourth piece 54 to the ninth piece 59 shown are formed.

[0226] [A combination of the second and third embodiments]

[0227] The second and third embodiments can be combined. For example, if there are three magnetic sheets 21 and 22 on one side and three magnetic sheets 21 and 22 on the other side, then on each side of the plurality of wirings 9, firstly, one sheet is arranged and hot-pressed, then two sheets are arranged and hot-pressed together. Alternatively, on each side of the plurality of wirings 9, firstly, two sheets are arranged and hot-pressed together, then one sheet is arranged and hot-pressed.

[0228] Example

[0229] The following examples of modulation, embodiments, and comparative examples further illustrate the present invention. However, the present invention is not limited to any particular modulation example, embodiment, or comparative example. Furthermore, the specific numerical values ​​of mixing ratios (including ratios), physical property values, parameters, etc., used in the following description can replace the corresponding upper limit values ​​(values ​​defined as "less than" or "less than") or lower limit values ​​(values ​​defined as "above" or "greater than") of the mixing ratios (including ratios), physical property values, parameters, etc., described in the "Specific Embodiments" above.

[0230] Modulation Example 1

[0231] (Preparation of adhesive)

[0232] Mix 24.5 parts by weight of epoxy resin (main agent), 24.5 parts by weight of phenolic resin (curing agent), 1 part by weight of imidazole compound (curing accelerator), and 50 parts by weight of acrylic resin (thermoplastic resin) to prepare an adhesive.

[0233] Example 1

[0234] (Equivalent to the first implementation method)

[0235] like Figure 1 As shown, firstly, a dry laminator (manufactured by Nikko Corporation) is prepared as the aforementioned hot pressing device 2 (the first step is carried out).

[0236] The magnetic particles and the binder of Modulation Example 1 were formulated and mixed in a manner that was in the volume ratio described in Table 1, and the first magnetic sheet 21 and the second magnetic sheet 22 (sheet 1 to sheet 9 59) were made in a manner that was in the type and volume ratio of the magnetic particles described in Table 1.

[0237] Multiple wirings with a radius of 130μm were prepared.

[0238] Next, as Figure 7 As shown, the first release piece 14, the first magnetic piece 21, multiple wires 9, and the second release piece 7 are sequentially arranged on the first pressure surface 61 of the first mold 3. The distance L0 between adjacent wires 9 is 240 μm.

[0239] After that, as Figure 3 As shown, the outer frame component 81 is sealed to the first mold 3, forming the first sealed space 84. Next, the vacuum pump 16 is driven to depressurize the first sealed space 84, forming a depressurized space 85 (fourth step). The air pressure in the depressurized space 85 is 2666 Pa (20 torr).

[0240] Then, the inner frame component 5 is pressed against the first mold 3 to form a second sealed space 45 with a pressure of 2666 Pa smaller than the decompression space 85 (the fifth step).

[0241] After that, as Figure 8 As shown, the second mold 4 is brought close to the first mold 3, and the magnetic sheet 8 and multiple wires 9 are hot-pressed (step 6) through the flowable flexible sheet 6, the second release sheet 7, and the first release sheet 14. The hot-pressing temperature is 170°C, and the time is 15 minutes. The hot-pressing pressure is as described in Tables 1 and 5.

[0242] As a result, the thermosetting resin of the first magnetic sheet 21 is cured, forming a precursor magnetic layer 31 having the above-described shape. Thus, an inductor precursor 40 comprising a plurality of wirings 9 and the precursor magnetic layer 31 is manufactured.

[0243] Then, the inductor precursor 40 is removed from the self-heating and pressing device 2. In the inductor precursor 40, one end face 95 and the other end face 96 of the plurality of wirings 9 in the thickness direction are exposed from the precursor magnetic layer 31. The thickness of the thin-walled portion 94 is 35 μm.

[0244] Furthermore, the first release piece 14 was replaced. Additionally, the second release piece 7 was also replaced.

[0245] Next, as Figure 9 As shown, the inductor front body 40 is clamped by the first piece 51 to the ninth piece 59 on one side and the first piece 51 to the ninth piece 59 on the other side, and the front body laminate 41 is fabricated using a flatbed press. The conditions of the flatbed press are: temperature 110℃, 1 minute, and pressure 0.9MPa (gauge pressure 2kN).

[0246] Next, the precursor laminate 41 is positioned between the first release sheet 14 and the second release sheet 7 (third step), as follows. Figure 10 As shown, hot pressing (steps 4 to 6) was performed using hot pressing device 2. The hot pressing temperature was 170°C, and the time was 15 minutes. The hot pressing pressure is as recorded in Tables 1 and 5.

[0247] Thus, an inductor 1 is manufactured, comprising a plurality of wirings 9 and a magnetic layer 30 covering the plurality of wirings 9 in a manner that spans across the adjacent wirings 9.

[0248] The magnetic layer 30 includes: an inner magnetic layer 36 containing carbonyl iron powder (spherical shape) formed from the first piece 51 to the third piece 53 of the first magnetic sheet 21 and the second magnetic sheet 22; and an outer magnetic layer 37 containing Fe-Si alloy (flat shape) formed from the fourth piece 54 to the ninth piece 59 of the second magnetic sheet 22.

[0249] Example 2

[0250] (Equivalent to the second implementation method)

[0251] like Figure 1 As shown, firstly, a dry laminator (manufactured by Nikko Corporation) is prepared as the aforementioned hot pressing device 2 (the first step is carried out).

[0252] In addition, the magnetic particles and the binder of Modulation Example 1 were formulated and mixed in a manner that was in the volume ratio described in Table 2, and the first magnetic sheet 21 and the second magnetic sheet 22 (sheet 1 to sheet 9 59) were manufactured in a manner that was in the type and volume ratio of the magnetic particles described in Table 2.

[0253] Multiple wirings with a radius of 130μm were prepared.

[0254] like Figure 11 and Figure 15 As shown in Figure A, then, between the first demolding plate 14 and the second demolding plate 7 of the hot pressing apparatus 2, the first piece 51 on the other side, a plurality of wires 9, and the first piece 51 on one side are sequentially arranged upstream in the direction of pressure (step 3). Afterwards, they are hot-pressed to obtain the inductor 1 (steps 4 to 6), and the inductor 1 is removed from the hot pressing apparatus 2. Furthermore, the hot pressing temperature is 170°C, and the time is 15 minutes. The hot pressing pressure is as described in Tables 2 and 5.

[0255] like Figure 15 As shown in B, the first release piece 14 is replaced, and the second release piece 7 is replaced. Then, between the first release piece 14 and the second release piece 7, the second piece 52 on the other side, the inductor 1, and the second piece 52 on one side are sequentially arranged upstream in the pressure direction (step 3). Then, they are hot-pressed to obtain the inductor 1 (steps 4 to 6), and the inductor 1 is removed from the hot-pressing device 2. Then, as... Figure 15 C~ Figure 15 As shown in Figure I, the aforementioned treatment was repeated for pieces 3 through 9 (59). In each of the above hot presses, the temperature was 170°C and the time was 15 minutes. The hot press pressures are as described in Tables 2 and 5.

[0256] Therefore, as Figure 16 As shown, an inductor 1 is manufactured comprising a plurality of wirings 9 and a magnetic layer 30 covering the plurality of wirings 9 in a manner that spans across the plurality of adjacent wirings 9.

[0257] The magnetic layer 30 includes: an inner magnetic layer 36 containing carbonyl iron powder (spherical shape) formed by the first sheet 51 to the third sheet 53; and an outer magnetic layer 37 containing Fe-Si alloy (flat shape) formed by the fourth sheet 54 to the ninth sheet 59.

[0258] Example 3 (equivalent to the third implementation method)

[0259] like Figure 1 As shown, firstly, a dry laminator (manufactured by Nikko Corporation) is prepared as the aforementioned hot pressing device 2 (the first step is carried out).

[0260] In addition, the magnetic particles and the binder of Modulation Example 1 were formulated and mixed in a manner that was in the volume ratio described in Table 3, and the first magnetic sheet 21 and the second magnetic sheet 22 (sheet 1 to sheet 9 59) were manufactured in a manner that was in the type and volume ratio of the magnetic particles described in Table 3.

[0261] Multiple wirings with a radius of 130μm were prepared.

[0262] like Figure 19As shown, multiple wires 9 are then clamped using the first piece 51 to the ninth piece 59 on the other side and the first piece 51 to the ninth piece 59 on one side, and a laminate 48 is fabricated using a flatbed press. The conditions for the flatbed press are: temperature 110°C, 1 minute, and pressure 0.9 MPa (gauge pressure 2 kN). In the laminate 48, the ninth piece 59 to the first piece 51 on the other side, multiple wires 9, and the first piece 51 to the ninth piece 59 on one side are arranged sequentially on the side facing the thickness direction.

[0263] Next, the laminate 48 is positioned between the first release plate 14 and the second release plate 7 of the hot pressing device 2 (third step), and then, as follows... Figure 18 As shown, inductor 1 is obtained by hot pressing laminate 48 (steps 4 to 6). Furthermore, the hot pressing temperature is 170°C, and the time is 15 minutes. The hot pressing pressure is as described in Tables 3 and 5.

[0264] Therefore, as Figure 18 As shown, an inductor 1 is fabricated comprising a plurality of wirings 9 and a magnetic layer 30 covering the plurality of wirings 9 in a manner that spans across the plurality of adjacent wirings 9.

[0265] The magnetic layer 30 includes: an inner magnetic layer 36 containing carbonyl iron powder (spherical shape) formed by the first sheet 51 to the third sheet 53; and an outer magnetic layer 37 containing Fe-Si alloy (flat shape) formed by the fourth sheet 54 to the ninth sheet 59.

[0266] Example 4 (equivalent to a variation of the third embodiment)

[0267] No pressure was applied using a flatbed press; otherwise, the process was the same as in Example 3. The hot pressing pressures are as described in Tables 4 and 5.

[0268] Comparative Example 1

[0269] A flatbed press was used instead of isostatic pressing, and the pressure of the flatbed press was set lower than that in Example 1. Otherwise, the process was the same as in Example 1. That is, isostatic pressing was not performed, and the pressure of the flatbed press was set to 0.4 MPa.

[0270] Comparative Example 2

[0271] A flatbed press was used instead of isostatic pressing, and the pressure of the flatbed press was set higher than that in Example 1. Otherwise, the process was the same as in Example 1. That is, isostatic pressing was not performed, and the pressure of the flatbed press was set to 2.7 MPa.

[0272] Comparative Example 3

[0273] A flatbed press was used instead of isostatic pressing, and the pressure of the flatbed press was set lower than that in Example 2. Otherwise, the process was the same as in Example 1. That is, isostatic pressing was not performed, and the pressure of the flatbed press was set to 0.4 MPa.

[0274] Comparative Example 4

[0275] A flatbed press was used instead of isostatic pressing, and the pressure of the flatbed press was set higher than that in Example 2. Otherwise, the process was the same as in Example 1. That is, isostatic pressing was not performed, and the pressure of the flatbed press was set to 3.6 MPa.

[0276] Comparative Example 5

[0277] A flatbed press was used instead of isostatic pressing, and the pressure of the flatbed press was set lower than that in Example 3. Otherwise, the process was the same as in Example 1. That is, isostatic pressing was not performed, and the pressure of the flatbed press was set to 0.4 MPa.

[0278] Comparative Example 6

[0279] A flatbed press was used instead of isostatic pressing, and the pressure of the flatbed press was set higher than that in Example 3. Otherwise, the process was the same as in Example 1. That is, isostatic pressing was not performed, and the pressure of the flatbed press was set to 3.6 MPa.

[0280] <Evaluation>

[0281] [Gap in the magnetic layer]

[0282] SEM observation was performed on the cross-section of the inductor 1 in each embodiment and comparative example to confirm whether there were gaps in the magnetic layer 30 at adjacent wiring 9. The evaluation was carried out according to the following criteria.

[0283] ×: A gap was observed in the magnetic layer 30 near the opposite face 99 of the adjacent wiring 9.

[0284] ○: The aforementioned gap was not observed on the magnetic layer 30.

[0285] [Changes in the distance between multiple wirings]

[0286] Viewing the central portion of the inductor 1 along its length in each embodiment and comparative example from above, the distance L1 between adjacent wirings 9 in the inductor 1 was measured. Furthermore, an evaluation was conducted based on its relationship with the distance L0 between adjacent wirings 9 before hot pressing, as described below.

[0287] ◎: 1.0 ≤ L1 / L0 < 1.1

[0288] ○: 1.1 ≤ L1 / L0 < 1.3

[0289] ×:1.3≤L1 / L0

[0290] [Operational]

[0291] The workability of the manufacturing methods of the inductor 1 in each embodiment and each comparative example was evaluated according to the following criteria.

[0292] ◎: No temporary adhesive is used; no inductor precursor is formed; and there is no need for multiple hot pressing corresponding to multiple magnetic sheets. Furthermore, the manufacturing time is minimal. Therefore, it offers excellent workability.

[0293] ○: Temporary adhesive is used, but it does not form the inductor precursor. Furthermore, there is no multiple hot-pressing process corresponding to multiple magnetic sheets. Compared to the "◎" rating, the manufacturing time is longer. Therefore, the workability is excellent.

[0294] △: Temporary bonding exists to form the inductor precursor, but there is no multiple hot-pressing process corresponding to multiple magnetic sheets. Compared to the "○" rating, the manufacturing time is longer. Therefore, the workability is good.

[0295] ×: Temporary bonding exists, forming the inductor precursor, and multiple hot-pressing processes are involved, corresponding to multiple magnetic sheets. Furthermore, compared to a "△" rating, the manufacturing time is longer. Therefore, workability is lower.

[0296] [Appearance]

[0297] The appearance of the inductor 1 in each embodiment and each comparative example was evaluated according to the following criteria.

[0298] ×: Cracks were observed.

[0299] ○: No cracks were observed.

[0300] [Table 1]

[0301]

[0302] [Table 2]

[0303]

[0304] [Table 3]

[0305]

[0306] [Table 4]

[0307]

[0308] [Table 5]

[0309]

[0310] Furthermore, the above-described invention is provided as an illustrative embodiment of the invention, but this is merely illustrative and not intended to limit the scope of the invention. Variations of the invention that will be apparent to those skilled in the art are included in the foregoing claims.

[0311] Industrial availability

[0312] The manufacturing method of inductors is used to manufacture inductors.

[0313] Explanation of reference numerals in the attached figures

[0314] 1. Inductor; 2. Hot pressing device; 3. First mold; 4. Second mold; 5. Inner frame component; 6. Flowable flexible sheet; 8. Magnetic sheet; 9. Wiring; 12. Buffer film; 18. One end face; 19. The other end face; 21. First magnetic sheet; 22. Second magnetic sheet; 30. Magnetic layer; 31. Precursor magnetic layer; 40. Inductor precursor; 45. Sealed space; 62. Second pressure surface; 81. Outer frame component; 95. One end face in the thickness direction; 96. The other end face in the thickness direction.

Claims

1. A method for manufacturing an inductor, characterized in that, The manufacturing method of this inductor includes: In the first step, a hot pressing device is prepared, comprising: a first mold; a second mold spaced apart from the first mold in the pressing direction and smaller than the first mold; a frame member surrounding the second mold and spaced apart from the first mold in the pressing direction, the frame member being movable relative to the second mold in the pressing direction; and a flowable flexible sheet disposed on the pressing surface of the second mold facing the first mold; and In the second step, an inductor is manufactured by hot-pressing a magnetic sheet containing magnetic particles and thermosetting resin, which is smaller than the flowable flexible sheet, and a plurality of spaced-apart wires using the hot-pressing device. This magnetic layer contains a cured form of the magnetic particles and the thermosetting resin and covers the plurality of wires in a manner that spans across the spaces between adjacent wires. The second step includes: In the third step, the magnetic sheet, the plurality of wirings, and the release sheet are placed in a manner that overlaps with the fluid flexible sheet when projected along the pressure direction. In the fifth step, the frame member is pressed against the first mold; and In the sixth step, the second mold is brought close to the first mold, and the magnetic sheet and the plurality of wires are hot-pressed through the fluid flexible sheet and the release sheet.

2. The method for manufacturing an inductor according to claim 1, characterized in that, The hot pressing device further includes an outer frame member that surrounds the frame member and is spaced apart from the first mold. The outer frame member is capable of contacting the first mold and has an exhaust port connected to a vacuum pump via an exhaust line. After the third step and before the fifth step, there is a fourth step in which the outer frame member is brought into contact with the first mold to form a decompression space.

3. The method for manufacturing an inductor according to claim 1 or 2, characterized in that, The release sheet includes a buffer film.

4. The method for manufacturing an inductor according to claim 1, characterized in that, The magnetic sheet includes a first magnetic sheet and a second magnetic sheet. The second step includes: The process of fabricating an inductor precursor involves using the aforementioned hot-pressing device to hot-press the first magnetic sheet, thereby fabricating an inductor precursor including a first magnetic layer that spans between adjacent wirings and exposes one end face of the wirings in the thickness direction; and The process of forming a magnetic layer involves using the hot pressing device to hot press the inductor precursor and the second magnetic sheet to form a magnetic layer covering the entire circumference of the wiring.

5. The method for manufacturing an inductor according to claim 2, characterized in that, The magnetic sheet includes a first magnetic sheet and a second magnetic sheet. The second step includes: The process of fabricating an inductor precursor involves using the aforementioned hot-pressing device to hot-press the first magnetic sheet, thereby fabricating an inductor precursor including a first magnetic layer that spans between adjacent wirings and exposes one end face of the wirings in the thickness direction; and The process of forming a magnetic layer involves using the hot pressing device to hot press the inductor precursor and the second magnetic sheet to form a magnetic layer covering the entire circumference of the wiring.

6. The method for manufacturing an inductor according to claim 3, characterized in that, The magnetic sheet includes a first magnetic sheet and a second magnetic sheet. The second step includes: The process of fabricating an inductor precursor involves using the aforementioned hot-pressing device to hot-press the first magnetic sheet, thereby fabricating an inductor precursor including a first magnetic layer that spans between adjacent wirings and exposes one end face of the wirings in the thickness direction; and The process of forming a magnetic layer involves using the hot pressing device to hot press the inductor precursor and the second magnetic sheet to form a magnetic layer covering the entire circumference of the wiring.

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