Substrate with built-in inductor and method for manufacturing substrate with built-in inductor

Abstract

This substrate with a built-in inductor comprises: a substrate member having an opening that opens from one surface in the thickness direction to the other surface in the thickness direction; and an inductor part disposed in the opening. The inductor part is provided with a magnetic layer and a metal pin. The metal pin extends along the thickness direction.

Description

Inductor-integrated substrate and method for manufacturing an inductor-integrated substrate

[0001] This disclosure relates to an inductor-embedded substrate and a method for manufacturing an inductor-embedded substrate.

[0002] Conventionally, inductor-embedded substrates having a core substrate and an inductor are known (see, for example, Patent Document 1). Specifically, the inductor-embedded substrate described in Patent Document 1 comprises a core substrate with an opening formed therein, a magnetic resin filled in the opening and having through holes, a through-hole conductor (plating film) formed in the through holes, and a resin filler filled in the through-hole conductor.

[0003] Japanese Patent Publication No. 2019-220504

[0004] On the other hand, in the inductor-embedded substrate described in Patent Document 1, the through-hole conductors are formed by electrolytic copper plating and electroless plating. In order to ensure excellent conductivity, it is necessary to ensure a sufficient thickness of the plating film, which results in the drawback of being time-consuming to manufacture. Furthermore, if the manufacturing time is shortened, it is not possible to ensure a sufficient thickness of the plating film, resulting in the drawback of poor conductivity.

[0005] The present disclosure aims to provide an inductor-embedded substrate and a method for manufacturing an inductor-embedded substrate that have high conductivity and can be manufactured efficiently.

[0006] The present disclosure [1] includes a substrate member having an opening that extends from one side in the thickness direction to the other side in the thickness direction, and an inductor portion disposed in the opening, wherein the inductor portion includes a magnetic layer and metal pins, the metal pins extending along the thickness direction, and comprises an inductor-embedded substrate.

[0007] Such inductor-integrated circuit boards are equipped with metal pins. Therefore, compared to cases where metal conductors are formed by plating, they offer higher conductivity and can be manufactured more efficiently.

[0008] The present disclosure [2] includes the inductor-embedded substrate described in [1], wherein the magnetic layer contacts the inner circumferential surface of the substrate member facing the opening and covers the outer circumferential surface of the metal pin.

[0009] In such an inductor-integrated substrate, the magnetic layer is positioned to contact the inner surface of the substrate member facing the opening and to cover the outer surface of the metal pins. This improves the magnetic properties of the inductor.

[0010] The present disclosure [3] includes an inductor-embedded substrate according to [1] or [2], wherein in the thickness direction, one surface of the substrate member and one end surface of the metal pin are flush.

[0011] In such an inductor-integrated substrate, one side of the substrate material and one end face of the metal pin are flush in the thickness direction. Therefore, when forming a conductor pattern on one side of the substrate material in the thickness direction, a reliable connection with the metal pin can be ensured.

[0012] This disclosure [4] includes an inductor-embedded substrate according to any one of [1] to [3] above, wherein the magnetic layer comprises a first magnetic layer and a retaining layer for holding the metal pins.

[0013] In such an inductor-integrated substrate, the magnetic layer comprises a first magnetic layer and a retaining layer for holding metal pins. Therefore, the clearance between the metal pins and the magnetic layer can be easily adjusted. As a result, manufacturability can be improved.

[0014] The present disclosure [5] includes an inductor-embedded substrate according to any one of the above [4], wherein the first magnetic layer is in contact with the inner circumferential surface of the substrate member facing the opening, and the retaining layer is disposed between the first magnetic layer and the metal pin in a planar direction perpendicular to the thickness direction and covers the outer circumferential surface of the metal pin.

[0015] In such an inductor-integrated substrate, the first magnetic layer contacts the inner circumferential surface of the substrate member facing the opening, and the retaining layer is positioned between the first magnetic layer and the metal pin in a plane direction perpendicular to the thickness direction, covering the outer circumferential surface of the metal pin. Therefore, the clearance between the metal pin and the magnetic layer can be easily adjusted. As a result, manufacturability can be improved.

[0016] The present disclosure [6] includes an inductor-embedded substrate as described in [4] or [5] above, wherein the retaining layer comprises at least one selected from the group consisting of a second magnetic layer, a conductive layer, and an insulating resin layer.

[0017] In such an inductor-integrated substrate, the retaining layer consists of at least one selected from the group comprising a second magnetic layer, a conductive layer, and an insulating resin layer. Therefore, the clearance between the metal pins and the magnetic layer can be easily adjusted. As a result, manufacturability can be improved. Furthermore, the retaining layer can be selected according to the application of the inductor-integrated substrate.

[0018] This disclosure [7] states that the coefficient of thermal expansion of the substrate member is 3.0 × 10 －５ It includes an inductor-embedded substrate as described in any one of the above items [1] to [6], which is below / ℃.

[0019] In such an inductor-integrated substrate, the coefficient of thermal expansion of the substrate material is 3.0 × 10 －５ The temperature is below / °C. In other words, the rate of dimensional change in the substrate material with respect to temperature changes is small. As a result, displacement of metal pins due to dimensional changes in the substrate material is suppressed, and the temperature reliability of the inductor-embedded substrate is improved.

[0020] The present disclosure [8] includes an inductor-embedded substrate according to any one of the above [1] to [7], wherein the substrate member is made of an insulating inorganic material.

[0021] In such inductor-integrated substrates, the substrate material is made of an insulating inorganic material. Therefore, the coefficient of thermal expansion of the substrate material can be reliably reduced. As a result, displacement of metal pins due to dimensional changes in the substrate material is suppressed, further improving the temperature reliability of the inductor-integrated substrate.

[0022] The present disclosure [9] includes a method for manufacturing an inductor-embedded substrate, comprising: a preparation step of preparing a substrate member having an opening that extends from one surface in the thickness direction to the other surface in the thickness direction; a first magnetic layer forming step of forming a first magnetic layer in the opening; a through hole forming step of forming a through hole that penetrates from one surface in the thickness direction to the other surface in the thickness direction of the first magnetic layer; and a placement step of inserting a metal pin into the through hole.

[0023] This method of manufacturing an inductor-embedded substrate includes a placement step in which metal pins are inserted into through-holes, making it possible to efficiently manufacture inductor-embedded substrates with high conductivity.

[0024] The present disclosure

[10] further includes a method for manufacturing an inductor-embedded substrate according to [9], comprising a retaining layer forming step, after the arrangement step, forming a retaining layer between the inner surface of the first magnetic layer facing the through hole and the outer surface of the metal pin.

[0025] In this method for manufacturing an inductor-embedded substrate, after the placement step, a retaining layer formation step is further included, in which a retaining layer is formed between the inner surface of the first magnetic layer facing the through hole and the outer surface of the metal pin. Therefore, the clearance between the outer surface of the metal pin and the inner surface of the first magnetic layer facing the through hole can be easily adjusted. As a result, manufacturability can be improved.

[0026] This disclosure

[11] includes a method for manufacturing an inductor-embedded substrate as described in

[10] , wherein the retaining layer comprises at least one selected from the group consisting of a second magnetic layer, a conductive layer, and an insulating resin layer.

[0027] In this method of manufacturing an inductor-embedded substrate, the retaining layer consists of at least one selected from the group comprising a second magnetic layer, a conductive layer, and an insulating resin layer. Therefore, the clearance between the metal pins and the magnetic layer can be easily adjusted. As a result, manufacturability can be improved. Furthermore, the retaining layer can be selected according to the application of the inductor-embedded substrate.

[0028] The inductor-embedded substrate of this disclosure comprises a substrate member having an opening that extends from one side in the thickness direction to the other side in the thickness direction, and an inductor portion disposed in the opening, wherein the inductor portion comprises metal pins and a magnetic layer, and the metal pins extend along the thickness direction. Therefore, it has high conductivity and can be manufactured efficiently.

[0029] The method for manufacturing an inductor-embedded substrate according to this disclosure comprises a preparation step of preparing a substrate member having an opening that extends from one side in the thickness direction to the other side in the thickness direction; a first magnetic layer formation step of forming a first magnetic layer in the opening; a through-hole formation step of forming a through-hole that penetrates from one side in the thickness direction to the other side in the thickness direction of the first magnetic layer; and an arrangement step of inserting metal pins into the through-hole. Therefore, an inductor-embedded substrate with high conductivity can be efficiently manufactured.

[0030] Figure 1 shows a perspective view of one embodiment of the inductor-embedded substrate of the present disclosure. Figure 2 shows a cross-sectional view of the inductor-embedded substrate of Figure 1 along line A-A. Figures 3A to 3D show a method for manufacturing the inductor-embedded substrate shown in Figures 1 and 2. Figure 3A shows a step of preparing the substrate material, Figure 3B shows a step of forming the first magnetic layer, Figure 3C shows a step of forming through holes in the first magnetic layer, and Figure 3D shows a step of inserting metal pins into the through holes. Figure 4 shows a cross-sectional view of a modified example of the inductor-embedded substrate of the present disclosure.

[0031] 1. An embodiment of the inductor-integrated circuit board of the present disclosure will be described with reference to Figures 1 and 2.

[0032] The inductor-integrated substrate 1 is a component of an electronic device (e.g., a wiring circuit board), that is, a part for manufacturing an electronic device, and does not include electronic elements (e.g., chips, capacitors). It is a device that is distributed as a standalone component and is industrially usable.

[0033] As shown in Figure 1, the inductor-embedded substrate 1 has one surface (one surface in the thickness direction) and another surface (the other surface in the thickness direction) on the opposite side in the thickness direction. The inductor-embedded substrate 1 has a shape that extends in a plane direction perpendicular to the thickness direction. The inductor-embedded substrate 1 has multiple sides that connect the one surface in the thickness direction and the other surface in the thickness direction. The inductor-embedded substrate 1 has, for example, a substantially rectangular parallelepiped shape.

[0034] Note that the thickness direction is the direction in which a metal pin 5, which will be described later, extends. In addition, among the planar directions orthogonal to the thickness direction, one predetermined direction (the left-right direction on the paper surface of Fig. 1) may be referred to as the first direction. Furthermore, the direction orthogonal to the first direction in the planar direction (the depth direction on the paper surface of Fig. 1) may be referred to as the second direction.

[0035] The inductor built-in substrate 1 includes a substrate member 2 having an opening 21 that opens from one side in the thickness direction to the other side in the thickness direction, and an inductor portion 3 disposed in the opening 21. The inductor built-in substrate 1 may include a substrate member 2 having one opening 21 and one inductor portion 3 disposed in the one opening 21, or may include a substrate member 2 having a plurality of openings 21 and a plurality of inductor portions 3 respectively disposed in the plurality of openings 21. The inductor built-in substrate 1 shown in Fig. 1 includes a substrate member 2 having a plurality of openings 21 and a plurality of inductor portions 3 respectively disposed in the plurality of openings 21.

[0036] In the present embodiment, in the inductor built-in substrate 1, as shown in Fig. 1, a plurality of inductor portions 3 are aligned and arranged at intervals from each other in the substrate member 2. Also, as shown in Fig. 2, the substrate member 2 and the inductor portions 3 are alternately arranged. More specifically, in the inductor built-in substrate 1, the substrate member 2 and the inductor portions 3 are alternately arranged in both the first direction and the second direction.

[0037] Furthermore, although not shown, in the thickness direction, a conductor pattern that connects between the plurality of inductor portions 3 or connects the inductor portions 3 and the outside may be formed on one side and / or the other side of the inductor built-in substrate 1.

[0038] 1.1. Substrate Member The substrate member 2 forms the outer shape of the inductor built-in substrate 1. In the thickness direction, the substrate member 2 has one surface (one side in the thickness direction) and the other surface on the opposite side (the other side in the thickness direction). The substrate member 2 has a shape extending in a planar direction orthogonal to the thickness direction. The substrate member 2 has a plurality of side surfaces connecting the one side in the thickness direction and the other side in the thickness direction. The substrate member 2 has, for example, a substantially rectangular parallelepiped shape.

[0039] In this embodiment, one surface of the substrate member in the thickness direction forms one surface of the inductor-embedded substrate in the thickness direction, and the other surface of the substrate member in the thickness direction forms the other surface of the inductor-embedded substrate in the thickness direction. Further, the plurality of side surfaces of the substrate member form the plurality of side surfaces of the inductor-embedded substrate.

[0040] The substrate member 2 has an opening 21 that opens from one surface in the thickness direction to the other surface in the thickness direction. In this embodiment, the substrate member 2 includes a plurality of openings 21 that open from one surface in the thickness direction to the other surface in the thickness direction. The plurality of openings 21 are arranged in alignment spaced apart from each other in both the first direction and the second direction.

[0041] The shape of the opening 21 is appropriately adjusted according to the shape of the metal pin 5. The shape of the opening 21 is, for example, a substantially straight shape (substantially I-shape) penetrating in the thickness direction of the substrate member in a cross-sectional view. In this embodiment, the shape of the opening 21 is substantially cylindrical. When the shape of the opening 21 is substantially cylindrical, the shape when viewed from the thickness direction (in plan view) is substantially circular (substantially circular in plan view).

[0042] The substrate member 2 has an inner peripheral surface facing the opening 21 corresponding to each of the openings 21.

[0043] The dimensions of the substrate member 2 are not particularly limited. The length of the substrate member 2 in the thickness direction is, for example, 1 µm or more, preferably 2 µm or more, and for example, 50 mm or less, preferably 20 mm or less. The length of the substrate member 2 in the first direction is not particularly limited, and is, for example, 1 mm or more, and for example, 1000 mm or less. The length of the substrate member 2 in the second direction is not particularly limited, and is, for example, 1 mm or more, and for example, 1000 mm or less.

[0044] The thickness of the substrate member 2 corresponds to the length of the opening 21 in the thickness direction.

[0045] When viewed from the thickness direction (in plan view), the maximum length of the opening 21 is, for example, 1 µm or more, preferably 10 µm or more, and for example, 100 mm or less, preferably 50 mm or less. When the opening 21 is substantially circular in plan view, the above-described maximum length corresponds to the diameter of the opening 21.

[0046] In the first direction, the spacing between adjacent openings 21 is, for example, 1 μm or more, preferably 2 μm or more, and also, for example, 100 mm or less, preferably 50 mm or less. In the second direction, the spacing between adjacent openings 21 is, for example, 1 μm or more, preferably 2 μm or more, and also, for example, 100 mm or less, preferably 50 mm or less.

[0047] Examples of materials for the substrate member 2 include insulating materials. Examples of insulating materials include resins (organic materials) and insulating inorganic materials. Preferably, insulating inorganic materials are used. In other words, the substrate member 2 is made of an insulating material, for example. Preferably, the substrate member 2 is made of an insulating inorganic material.

[0048] If the substrate member 2 is made of an insulating material, it is possible to suppress the occurrence of short circuits between the multiple inductor parts 3 arranged in the opening 21.

[0049] Examples of resins include epoxy resins, polyethersulfone resins, polyimide resins, polyester resins, and acrylic resins. Additionally, fiber-reinforced epoxy resins (e.g., glass epoxy resins) are also used.

[0050] Examples of insulating inorganic materials include glass materials, metalloid materials, and ceramic materials. Glass materials are preferred.

[0051] The glass material is not particularly limited and includes, for example, aluminosilicate glass, aluminoborosilicate glass, bariumborosilicate glass, soda-lime glass, soda-aluminosilicate glass, and quartz glass.

[0052] Examples of semimetallic materials include silicon.

[0053] Examples of ceramic materials include alumina, silica, silicon nitride, tantalum nitride, titanium carbide, silicon carbide, gallium nitride, and gypsum.

[0054] That is, examples of the substrate member 2 include a glass substrate, a silicon substrate, and a ceramic substrate. Preferably, it is a glass substrate.

[0055] The coefficient of linear expansion of the substrate member 2 is, for example, 1.0×10 －４ / °C or less, preferably 5.0×10 －５ / °C or less, more preferably 3.0×10 －５ / °C or less, still more preferably 1.0×10 －５ / °C or less, particularly preferably 8.0×10 －６ / °C or less, and most preferably 5.0×10 －６ / °C or less. Further, the coefficient of linear expansion of the substrate member 2 is, for example, 1.0×10 －６ / °C or more.

[0056] The coefficient of linear expansion can be measured by a thermomechanical analyzer (TMA).

[0057] When the coefficient of linear expansion of the substrate member 2 is equal to or higher than the above lower limit, dimensional change of the substrate member 2 due to temperature change can be suppressed. As a result, the temperature reliability of the inductor-embedded substrate 1 can be improved.

[0058] 1.2. Inductor Section The inductor section 3 is disposed in the opening 21 of the substrate member 2. In the present embodiment, one inductor section 3 is disposed for the opening 21 of one substrate member 2.

[0059] In the thickness direction, one end of the inductor section 3 may protrude from one surface of the substrate member 2 toward one side in the thickness direction, or may be recessed toward the other side in the thickness direction. Further, in the thickness direction, one surface of the inductor section 3 and one surface of the substrate member 2 may be flush with each other. Preferably, in the thickness direction, one surface of the inductor section 3 and one surface of the substrate member 2 are flush with each other.

[0060] In the thickness direction, the other end of the inductor portion 3 may protrude from the other surface of the substrate member 2 to the other side in the thickness direction, or it may be recessed to one side in the thickness direction. Also, in the thickness direction, the other surface of the inductor portion 3 and the other surface of the substrate member 2 may be flush. Preferably, in the thickness direction, the other surface of the inductor portion 3 and the other surface of the substrate member 2 are flush.

[0061] If, in the thickness direction, one side of the inductor portion 3 and one side of the substrate member 2 are flush, and / or the other side of the inductor portion 3 and the other side of the substrate member 2 are flush, then at least one side of the inductor portion 3 can be easily connected to each other or to the outside.

[0062] The outer circumferential surface of the inductor portion 3 contacts the inner circumferential surface of the substrate member 2 facing the opening 21. Preferably, the entire outer circumferential surface of the inductor portion 3 contacts the entire inner circumferential surface of the substrate member 2 facing the opening 21.

[0063] The shape of the inductor portion 3 is, for example, the same as the opening 21 of the substrate member 2. The shape of the inductor portion 3 is, for example, a roughly straight shape (roughly I-shaped) in cross-sectional view. In this embodiment, the shape of the inductor portion 3 is roughly cylindrical. When the shape of the inductor portion 3 is roughly cylindrical, the shape when viewed from the thickness direction (in plan view) is roughly circular (roughly circular in plan view).

[0064] The dimensions of the inductor portion 3 are not particularly limited. In the thickness direction, the length of the inductor portion 3 is, for example, 1 μm or more, preferably 2 μm or more, and for example, 50 mm or less, preferably 20 mm or less. In the thickness direction, the length of the inductor portion 3 is preferably the same as the length of the substrate member 2.

[0065] The maximum length of the inductor portion 3 when viewed from the thickness direction, and the spacing between adjacent inductor portions 3 in the first and second directions, are the same as the opening 21 of the substrate member 2 described above.

[0066] The inductor section 3 comprises a magnetic layer 4 and metal pins 5. Preferably, the inductor section 3 comprises a magnetic layer 4 that contacts the inner circumferential surface of the substrate member 2 facing the opening 21, and metal pins 5 that are covered by the magnetic layer 4.

[0067] (1) Magnetic layer The magnetic layer 4 is placed in the opening 21 of the substrate member 2 together with the metal pins 5. More specifically, the magnetic layer 4 is in contact with the inner circumferential surface of the substrate member 2 facing the opening 21 and covers the metal pins 5.

[0068] At least a portion of the outer circumferential surface of the magnetic layer 4 contacts the inner circumferential surface of the substrate member 2 facing the opening 21. In this embodiment, the entire outer circumferential surface of the magnetic layer 4 contacts the entire inner circumferential surface of the substrate member 2 facing the opening 21.

[0069] Furthermore, the magnetic layer 4 covers at least a portion of the outer surface of the metal pin 5. In this embodiment, the magnetic layer 4 covers the entire outer surface of the metal pin 5.

[0070] The magnetic layer 4 extends in the thickness direction. In the thickness direction, one surface and the other surface of the magnetic layer 4, together with the metal pins 5, form one surface and the other surface of the inductor portion 3. In other words, in the thickness direction, one surface and the other surface of the magnetic layer 4 are preferably flush with one surface and the other surface of the substrate member 2.

[0071] The shape of the magnetic layer 4 is not particularly limited, and for example, it may be approximately cylindrical. When the shape of the magnetic layer 4 is approximately cylindrical, the shape when viewed from the thickness direction (in plan view) is approximately annular (approximately annular in plan view).

[0072] When the shape of the magnetic layer 4 is substantially cylindrical, the outer surface of the magnetic layer 4 contacts the inner surface of the substrate member 2 facing the opening 21, and the inner surface of the magnetic layer 4 contacts the outer surface of the metal pin 5. Preferably, the entire outer surface of the magnetic layer 4 contacts the entire inner surface of the substrate member 2 facing the opening 21, and the entire inner surface of the magnetic layer 4 contacts the entire outer surface of the metal pin 5.

[0073] The dimensions of the magnetic layer 4 are not particularly limited. In the thickness direction, the length of the magnetic layer 4 is, for example, 1 μm or more, preferably 2 μm or more, and also, for example, 50 mm or less, preferably 20 mm or less. In the thickness direction, the length of the magnetic layer 4 is preferably the same as the length of the substrate member 2. In the plane direction, the length of the magnetic layer 4 (the distance from the outer circumferential surface of the magnetic layer 4 to the contact surface between the magnetic layer 4 and the metal pin 5) is preferably substantially uniform. In the plane direction, the length of the magnetic layer 4 (the distance from the outer circumferential surface of the magnetic layer 4 to the contact surface between the magnetic layer 4 and the metal pin 5) is, for example, 1 μm or more, and also, for example, 2,000 μm or less.

[0074] The magnetic layer 4 has a first magnetic layer 41. Alternatively, the magnetic layer 4 may have a first magnetic layer 41 and a retaining layer 42. In this embodiment, the magnetic layer 4 consists of a first magnetic layer 41.

[0075] The first magnetic layer 41 contains a hardened binder and magnetic particles. As will be described in more detail later, the first magnetic layer 41 is formed by laminating and hardening multiple magnetic sheets, each containing a binder and magnetic particles.

[0076] The binder is a resin matrix that disperses magnetic particles. Examples of binders include thermosetting resins and thermoplastic resins. Alternatively, photocurable resins can also be used as binders.

[0077] Examples of thermosetting resins include epoxy resins, phenolic resins, melamine resins, thermosetting polyimide resins, unsaturated polyester resins, polyurethane resins, and silicone resins.

[0078] Examples of thermoplastic resins include acrylic resins, ethylene-vinyl acetate copolymers, polycarbonate resins, polyamide resins (e.g., 6-nylon, 6,6-nylon), thermoplastic polyimide resins, and saturated polyester resins (e.g., PET, PBT).

[0079] The binder may be a thermosetting resin or a thermoplastic resin, either individually or in combination. Preferably, a combination of a thermosetting resin and a thermoplastic resin is used. More preferably, a combination of an acrylic resin, an epoxy resin, and a phenolic resin is used.

[0080] The magnetic particles are uniformly (isotropically) dispersed in the magnetic layer 4. Examples of materials for the magnetic particles include soft magnetic materials and hard magnetic materials. From the viewpoint of inductance, soft magnetic materials are preferred as the material for the magnetic particles.

[0081] Examples of soft magnetic materials include a single metallic body containing one type of metallic element in a pure state, and an alloy body which is a eutectic (mixture) of one or more metallic elements (first metallic element) and one or more metallic elements (second metallic element) and / or non-metallic elements. These can be used individually or in combination.

[0082] Examples of a single metallic body include a pure metal consisting of only one type of metallic element (the first metallic element). The first metallic element is appropriately selected from the metallic elements used as the first metallic element in soft magnetic materials, and examples include iron (Fe), cobalt (Co), and nickel (Ni).

[0083] Furthermore, examples of single metallic bodies include a core containing only one type of metal element and inorganic and / or organic materials modifying part or all of the core, and a form obtained by decomposing (e.g., thermal decomposition) an organometallic compound or inorganic metallic compound containing a first metal element. More specifically, the latter form includes iron powder (sometimes referred to as carbonyl iron powder) obtained by thermal decomposition of an organoiron compound (specifically, carbonyl iron) containing iron as the first metal element. The organometallic compound or inorganic metallic compound that can obtain a single metallic body is not particularly limited and can be appropriately selected from known or conventional organometallic compounds or inorganic metallic compounds that can obtain a single metallic body of soft magnetic material.

[0084] The alloy is a eutectic mixture of one or more metallic elements (first metallic elements) and one or more metallic elements (second metallic elements) and / or non-metallic elements, and is not particularly limited as long as it can be used as a soft magnetic alloy.

[0085] The first metallic element is an essential element in an alloy, and examples include iron (Fe), cobalt (Co), and nickel (Ni). An alloy in which the first metallic element is Fe is called an Fe-based alloy, an alloy in which the first metallic element is Co is called a Co-based alloy, and an alloy in which the first metallic element is Ni is called a Ni-based alloy.

[0086] The second metallic element is an element (sub-component) secondarily contained in the alloy and is a metallic element that is miscible (eutectic) with the first metallic element. The second metallic element is not particularly limited and includes, for example, iron (Fe), cobalt (Co), nickel (Ni), chromium (Cr), aluminum (Al), copper (Cu), zirconium (Zr), niobium (Nb), tantalum (Ta), and zinc (Zn). These can be used alone or in combination of two or more.

[0087] Nonmetallic elements are elements (sub-components) that are incidentally present in the alloy and are miscible (eutectic) with the primary metallic element. Examples include boron (B), carbon (C), nitrogen (N), silicon (Si), phosphorus (P), and sulfur (S). These can be used individually or in combination of two or more.

[0088] Examples of Fe-based alloys include magnetic stainless steel (Fe-Cr-Al-Si alloy), Sendust (Fe-Si-Al alloy), Permalloy (Fe-Ni alloy), silicon copper (Fe-Cu-Si alloy), Fe-Si alloy, Fe-Si-B(-Cu-Nb) alloy, Fe-Si-Cr-Ni alloy, Fe-Si-Cr alloy, Fe-Si-Al-Ni-Cr alloy, and ferrite. From the viewpoint of magnetic properties, Sendust (Fe-Si-Al alloy) is preferred. Examples of Co-based alloys include Co-Ta-Zr and cobalt (Co)-based amorphous alloys. Examples of Ni-based alloys include Ni-Cr alloy.

[0089] The material for the magnetic particles is appropriately selected from the soft magnetic material and hard magnetic material described above so as to impart a desired relative permeability to the magnetic layer 4.

[0090] The magnetic particles are preferably made of iron. Examples of iron magnetic particles include iron powder obtained by thermal decomposition of an organic iron compound, more preferably carbonyl iron powder (relative permeability at 10 MHz: for example, 1.1 or more, preferably 3 or more, and for example, 25 or less, preferably 20 or less).

[0091] The shape of the magnetic particles is not particularly limited. In other words, the magnetic particles may be non-anisotropic or anisotropic. Examples of non-anisotropic magnetic particle shapes include spherical, granular, lump, and pellet shapes. Examples of anisotropic magnetic particle shapes include flattened (plate-like) and needle-like shapes.

[0092] When the magnetic particles are non-anisotropic magnetic particles, their average particle diameter (D50) is, for example, 0.1 μm or more, preferably 0.5 μm or more, and also, for example, 200 μm or less, preferably 150 μm or less.

[0093] When the magnetic particles are anisotropic magnetic particles, their average length is, for example, 3.5 μm or more, preferably 10 μm or more, and also, for example, 200 μm or less, preferably 150 μm or less.

[0094] The proportion of binder (cured material) in the first magnetic layer 41 is, for example, 20 volume% or more, preferably 30 volume% or more, and also, for example, 70 volume% or less, preferably 60 volume% or less. The proportion of magnetic particles in the magnetic layer 4 is, for example, 30 volume% or more, preferably 40 volume% or less, and also, for example, 80 volume% or less, preferably 70 volume% or less.

[0095] The first magnetic layer 41 may also contain additives such as thermosetting catalysts, inorganic particles, organic particles, and crosslinking agents, as needed.

[0096] (2) Metal pins The metal pins 5 extend along the thickness direction. In other words, the metal pins 5 are arranged such that the direction in which they extend is along the thickness direction.

[0097] The metal pin 5 extends along the thickness direction and is positioned in the opening 21 of the substrate member 2 together with the magnetic layer 4.

[0098] The position of the metal pin 5 in the opening 21 of the substrate member 2 is not particularly limited. The metal pin 5 may be positioned approximately in the center of the magnetic layer 4 in the planar direction, or it may be positioned at a location other than approximately in the center of the magnetic layer 4 in the planar direction. In this embodiment, the metal pin 5 is positioned approximately in the center of the magnetic layer 4 in the planar direction.

[0099] In other words, the metal pin 5 may or may not contact the inner circumferential surface of the substrate member 2 facing the opening 21. In this embodiment, the metal pin 5 does not contact the inner circumferential surface of the substrate member 2 facing the opening 21. In other words, the outer circumferential surface of the metal pin 5 is spaced apart from the inner circumferential surface of the substrate member 2 facing the opening 21. A magnetic layer 4 is placed between the outer circumferential surface of the metal pin 5 and the inner circumferential surface of the substrate member 2 facing the opening 21.

[0100] Furthermore, the metal pin 5 is covered with the magnetic layer 4. More specifically, the outer circumferential surface of the metal pin 5 is covered with the magnetic layer 4. In this embodiment, the entire outer circumferential surface of the metal pin 5 is covered with the magnetic layer 4. In other words, the outer circumferential surface of the metal pin 5 is in contact with the inner circumferential surface of the magnetic layer 4. Preferably, the entire outer circumferential surface of the metal pin 5 is in contact with the entire inner circumferential surface of the magnetic layer 4.

[0101] In the thickness direction, the metal pin 5 has one end and the other end. In the thickness direction, one side of the metal pin 5 is referred to as the one-end face, and the other side as the other-end face. In the thickness direction, one end of the metal pin 5 may protrude from one side of the substrate member 2 in the thickness direction, or it may be recessed in the other side in the thickness direction. In the thickness direction, the other end of the metal pin 5 may protrude from the other side of the substrate member 2 in the thickness direction, or it may be recessed in the thickness direction. In the thickness direction, the one-end face and the other-end face of the metal pin 5 may be flush with the one side and the other side of the substrate member 2, respectively.

[0102] In this embodiment, in the thickness direction, one surface of the substrate member 2 and one end surface of the metal pin 5 are flush, and the other surface of the substrate member 2 and the other end surface of the metal pin 5 are flush. In other words, in the thickness direction, one end surface and the other end surface of the metal pin 5, together with the magnetic layer 4, form one surface and the other surface of the inductor portion 3, respectively.

[0103] Furthermore, in the thickness direction, at least one of the one end face and the other end face of the metal pin 5 is exposed from the substrate member 2 and the magnetic layer 4. In this embodiment, in the thickness direction, each of the one end face and the other end face of the metal pin 5 is exposed from each of the one and the other sides of the substrate member 2 and the magnetic layer 4. In the thickness direction, at least one of the one end face and the other end face of the metal pin 5 is exposed from the substrate member 2 and the magnetic layer 4, so that at least one of the one end face and the other end face of the metal pin 5 can be used as an external terminal of the inductor-embedded substrate 1. In other words, in the thickness direction, at least one of the one end face and the other end face of the metal pin 5 is connectable to the outside.

[0104] The shape of the metal pin 5 is, for example, a roughly straight shape (roughly I-shaped) in cross-sectional view. In this embodiment, the shape of the metal pin 5 is roughly cylindrical. When the shape of the metal pin 5 is roughly cylindrical, the shape when viewed from the thickness direction (in plan view) is roughly circular (roughly circular in plan view). In addition, in the plane direction, the length of the metal pin 5 is preferably the same from one end face in the thickness direction to the other end face in the thickness direction.

[0105] Furthermore, if the shape of the metal pin 5 is approximately cylindrical (approximately circular when viewed from the thickness direction), the length of the metal pin 5 in the planar direction is the same, but is not limited to this. In other words, the length of the metal pin 5 in the planar direction does not have to be the same. Even if the length of the metal pin 5 in the planar direction is not the same, it is preferable that the length of the metal pin 5 in the planar direction is the same (uniform) across the thickness direction.

[0106] Examples of materials for the metal pin 5 include copper, silver, gold, aluminum, nickel, and alloys thereof. Copper is preferred. In other words, the metal pin 5 is preferably a copper pin.

[0107] The metal pin 5 is made of a metal having the following configuration (length in the direction in which the metal pin 5 extends, maximum length of the metal pin 5 when viewed from the thickness direction, and density of the metal pin 5). Preferably, it is made of copper having the following configuration. The metal pin 5 is made of metal only, and its outer surface is not insulated. In other words, the metal pin 5 is different from commercially available insulated wiring (insulated metal thin wires). Because the metal pin 5 is made of metal, its dimensions can be easily adjusted by polishing and cutting.

[0108] Furthermore, the metal pin 5 is an independent rod-shaped member made of metal. In other words, the metal pin 5 is different from metal conductors formed by metal plating and metal conductors made of metal paste. And, unlike the metal conductors described above, the metal pin 5 does not need to be formed separately in the manufacturing process of the inductor-embedded substrate, thus simplifying the process.

[0109] In the direction in which the metal pin 5 extends (thickness direction), the length of the metal pin 5 is, for example, 1 μm or more, preferably 2 μm or more, and, for example, 20 mm or less, preferably 10 mm or less. In the thickness direction, the length of the metal pin 5 is preferably the same as the length of the substrate member 2.

[0110] When viewed from the thickness direction, the maximum length of the metal pin 5 is, for example, 1 μm or more, preferably 10 μm or more, and, for example, 100 mm or less, preferably 50 mm or less. When the metal pin 5 is substantially circular in shape when viewed from the thickness direction, the above-mentioned maximum length corresponds to the diameter of the metal pin 5.

[0111] The density of the metal pin 5 is, for example, 1 g / cm³. ３ Preferably, 5 g / cm³ ３ In addition, for example, 20 g / cm³ ３ Preferably, 15 g / cm³ ３ The following applies:

[0112] 2. Manufacturing Method of Inductor-Integrated Substrate An embodiment of the manufacturing method of the inductor-integrated substrate of this disclosure will be described with reference to Figures 3A to 3D.

[0113] The method for manufacturing the inductor-embedded substrate shown in Figures 3A to 3D is the same method for manufacturing the inductor-embedded substrate 1 shown in Figures 1 and 2.

[0114] A method for manufacturing an inductor-embedded substrate comprises a preparation step of preparing a substrate member 2 having an opening 21 that extends from one side in the thickness direction to the other side in the thickness direction; a first magnetic layer formation step of forming a first magnetic layer 41 in the opening 21; a through hole formation step of forming a through hole 43 that penetrates the first magnetic layer 41 from one side in the thickness direction to the other side in the thickness direction; and a placement step of inserting a metal pin 5 into the through hole 43. Preferably, the method for manufacturing an inductor-embedded substrate comprises the preparation step, the first magnetic layer formation step, the through hole formation step, and the placement step in that order. Although not shown in the figures, the method for manufacturing an inductor-embedded substrate may include a molding step after the placement step in which one side of the inductor portion 3 (one end face of the metal pin 5) and one side of the substrate member 2 are made flush in the thickness direction, and / or the other side of the inductor portion 3 (the other end face of the metal pin 5) and the other side of the substrate member 2 are made flush.

[0115] (Preparation step) The preparation step involves preparing a substrate member 2 having an opening 21 that extends from one side in the thickness direction to the other side in the thickness direction, as shown in Figure 3A.

[0116] The method for forming the opening 21 in the substrate member 2 is not particularly limited. Examples of methods for forming the opening 21 in the substrate member 2 include non-contact cutting using a laser and chemical etching.

[0117] (First Magnetic Layer Formation Step) In the first magnetic layer formation step, as shown in Figure 3B, a first magnetic layer 41 is formed in the opening 21. In this embodiment, the first magnetic layer 41 corresponds to the magnetic layer 4 described above.

[0118] Specifically, a semi-cured (B-stage) magnetic sheet containing a binder and magnetic particles is formed. The magnetic sheet is formed by applying a varnish of a magnetic composition containing a binder, magnetic particles, and a solvent to a substrate (e.g., a metal substrate, a release sheet) to form a coating film. The coating film of the magnetic composition is then dried. During drying, the coating film of the magnetic composition is heated if necessary. Drying removes the solvent from the coating film of the magnetic composition. This forms a magnetic sheet.

[0119] As described above, the magnetic sheet is in a semi-cured state (Stage B), which is between the state where the binder is liquid (Stage A) and the state where it is fully cured (Stage C). In Stage B, the binder has hardened slightly, and the compressive modulus is lower than that of Stage C.

[0120] Next, multiple magnetic sheets are stacked. The number of magnetic sheets stacked is adjusted as appropriate according to the desired thickness of the magnetic layer.

[0121] Next, the magnetic sheet is embedded in the opening 21. Specifically, the magnetic sheet is heated to increase its fluidity and then embedded in the opening 21. Then, as shown below, the magnetic sheet is hardened to form the first magnetic layer 41 in the opening 21.

[0122] The magnetic sheet may be cured before being embedded in the opening 21, or after being embedded in the opening 21. Preferably, the magnetic sheet is cured after being embedded in the opening 21. When the magnetic sheet is cured after being embedded in the opening 21, it may be cured before the through-hole formation process, after the through-hole formation process and before the placement process, or after the placement process. Preferably, the magnetic sheet is cured before the through-hole formation process.

[0123] To cure a magnetic sheet, if the binder it contains is a thermosetting resin, the magnetic sheet is heated. If the binder it contains is a photocurable resin, the magnetic sheet is irradiated with light. This causes the magnetic sheet to fully harden (reach stage C).

[0124] Furthermore, if the magnetic sheet is cured after the through-hole formation process, the first magnetic layer 41 will be formed after the through-hole formation process, but this is acceptable.

[0125] Alternatively, the first magnetic layer 41 may be formed in the opening 21 by the method described below.

[0126] Specifically, first, a varnish of a magnetic composition containing a binder, magnetic particles, and a solvent is poured directly into the opening 21 of the substrate member 2. Next, the magnetic composition in the opening 21 is dried. During drying, the magnetic composition is heated if necessary. Drying removes the solvent from the magnetic composition. At this point, the magnetic composition is in a semi-cured state (stage B) as described above. Then, as shown below, the magnetic composition is cured to form the first magnetic layer 41 in the opening 21.

[0127] The magnetic composition may be cured before the through-hole formation process, after the through-hole formation process and before the placement process, or after the placement process.

[0128] To cure a magnetic composition, if the binder in the magnetic composition is a thermosetting resin, the magnetic composition is heated. If the binder in the magnetic composition is a photocurable resin, the magnetic composition is irradiated with light. This causes the magnetic composition to fully cure (reach the C stage).

[0129] Furthermore, if the magnetic composition is cured after the through-hole formation process, the first magnetic layer 41 will be formed after the through-hole formation process, but this is acceptable.

[0130] In this embodiment, the magnetic sheet in the B stage is heated to increase its fluidity and then embedded in the opening 21. By continuing to heat it, the magnetic sheet is cured, and the first magnetic layer 41 is formed in the opening 21. In other words, in this embodiment, the magnetic sheet is cured after being embedded in the opening 21 but before the through-hole formation process. The binder contained in the magnetic sheet is a thermosetting resin.

[0131] In Figure 3B, the first magnetic layer 41 is formed only on the opening 21 of the substrate member 2, but the method is not limited to this. Specifically, the first magnetic layer 41 may be formed on one surface and / or the other surface of the substrate member 2 in the thickness direction. In that case, the manufacturing method of the inductor-embedded substrate includes a molding step after the arrangement step in which one surface of the inductor portion 3 (one end face of the metal pin 5) and one surface of the substrate member 2 are made flush in the thickness direction, and / or the other surface of the inductor portion 3 (the other end face of the metal pin 5) and the other surface of the substrate member 2 are made flush.

[0132] (Through-hole formation process) As shown in Figure 3C, the through-hole formation process involves forming a through-hole 43 that penetrates from one side in the thickness direction of the first magnetic layer 41 to the other side in the thickness direction.

[0133] Specifically, a through hole 43 is formed in the first magnetic layer 41 located in the opening 21, extending from one side in the thickness direction to the other side in the thickness direction. In this embodiment, one through hole 43 is formed in the first magnetic layer 41 located in one opening 21. Multiple through holes 43 may be formed in the first magnetic layer 41 located in one opening 21. Methods for forming the through hole 43 include, for example, end milling, blasting, and dicing. Preferably, an end mill is used to form the through hole 43 in the first magnetic layer 41, extending from one side in the thickness direction to the other side in the thickness direction.

[0134] In other words, the first magnetic layer 41 has a through hole 43 that penetrates from one side in the thickness direction to the other side in the thickness direction, and in which a metal pin 5 is placed. The first magnetic layer 41 also has an inner circumferential surface that faces the through hole 43, corresponding to the through hole 43.

[0135] The shape of the through-hole 43 is adjusted as appropriate by the shape of the metal pin 5. For example, the shape of the through-hole 43 is a substantially straight shape (substantially I-shaped) that penetrates in the thickness direction of the first magnetic layer 41 when viewed in cross-section. In this embodiment, the shape of the through-hole 43 is substantially cylindrical. When the shape of the through-hole 43 is substantially cylindrical, the shape when viewed from the thickness direction (in plan view) is substantially circular (substantially circular in plan view).

[0136] The shape of the first magnetic layer 41 in which the through-hole 43 is formed is not particularly limited, and for example, it is a substantially cylindrical shape excluding the through-hole 43. In this embodiment, the shape of the first magnetic layer 41 is substantially cylindrical. When the shape of the first magnetic layer 41 is substantially cylindrical, the shape when viewed from the thickness direction (in plan view) is substantially annular (substantially annular in plan view).

[0137] The position of the through-hole 43 in the first magnetic layer 41 is not particularly limited. The position of the through-hole 43 in the magnetic layer 4 may be approximately in the center in the planar direction, or it may not be approximately in the center in the planar direction. In this embodiment, in the planar direction, the through-hole 43 is formed approximately in the center of the first magnetic layer 41 that is arranged in the opening 21.

[0138] In the thickness direction, the length of the through-hole 43 corresponds to the length of the first magnetic layer 41. When viewed from the thickness direction (in a plan view), the maximum length of the through-hole 43 is appropriately adjusted according to the dimensions of the metal pin 5. When viewed from the thickness direction (in a plan view), if the through-hole 43 is approximately circular in shape, the above-mentioned maximum length corresponds to the diameter of the through-hole 43.

[0139] In this way, a first magnetic layer 41 is formed having through holes 43 that penetrate from one side in the thickness direction to the other side in the thickness direction.

[0140] (Placement process) In the placement process, as shown in Figure 3D, a metal pin 5 is inserted into the through hole 43.

[0141] In this embodiment, the metal pin 5 is inserted such that at least a portion of its outer circumferential surface contacts at least a portion of the inner circumferential surface of the first magnetic layer 41 facing the through hole 43. More specifically, the metal pin 5 is inserted so that its outer circumferential surface contacts the inner circumferential surface of the first magnetic layer 41 facing the through hole 43, thereby fixing the metal pin 5 in place. In other words, the metal pin 5 is inserted so as to cover the first magnetic layer 41. Furthermore, one metal pin 5 is inserted into each through hole 43.

[0142] When viewed from the thickness direction, the maximum length of the metal pin 5 is less than or equal to the maximum length of the through hole 43. In this embodiment, when viewed from the thickness direction, the maximum length of the metal pin 5 is the same as the maximum length of the through hole 43.

[0143] As a result, an inductor portion 3 is formed, consisting of a first magnetic layer 41 and metal pins 5 covering the first magnetic layer 41.

[0144] In addition, in the thickness direction, one end of the metal pin 5 may protrude from one side of the substrate member 2, and the other end of the metal pin 5 may protrude from the other side of the substrate member 2. In that case, the manufacturing method of the inductor-embedded substrate includes a molding step after the arrangement step in which one side of the inductor portion 3 (one end face of the metal pin 5) and one side of the substrate member 2 are made flush in the thickness direction, and / or the other side of the inductor portion 3 (the other end face of the metal pin 5) and the other side of the substrate member 2 are made flush.

[0145] (Molding Process) Although not shown in the diagram, after the placement process, one side of the inductor portion 3 (one end face of the metal pin 5) and one side of the substrate member 2 are made flush in the thickness direction, and / or the other side of the inductor portion 3 (the other end face of the metal pin 5) and the other side of the substrate member 2 are made flush.

[0146] Specifically, after the placement process, the inductor portion 3 is polished so that one side (one end face of the metal pin 5) and one side of the substrate member 2 are flush, and / or the other side of the inductor portion 3 (the other end face of the metal pin 5) and the other side of the substrate member 2 are flush. If the first magnetic layer 41 is formed on one side and / or the other side of the substrate member 2 in the thickness direction, the first magnetic layer 41 is polished. Also, if one end of the metal pin 5 protrudes from one side of the substrate member 2 and / or the other end of the metal pin 5 protrudes from the other side of the substrate member 2 in the thickness direction, the metal pin 5 is polished.

[0147] In this manner, the inductor-integrated circuit board 1 is manufactured.

[0148] 3. Effects (1) The inductor-embedded substrate 1 of this disclosure is equipped with metal pins 5. Therefore, compared to the case in which metal conductors are formed by plating, it has higher conductivity and can be manufactured efficiently.

[0149] (2) In the inductor-embedded substrate 1 of the present disclosure, the magnetic layer 4 is arranged to be in contact with the inner circumferential surface of the substrate member 2 facing the opening 21, and the outer circumferential surface of the metal pin 5 is covered with the magnetic layer 4. As a result, the magnetic characteristics of the inductor portion 3 can be improved.

[0150] (3) In the inductor-embedded substrate 1 of this disclosure, one surface of the substrate member 2 and one end surface of the metal pin 5 are flush in the thickness direction. Therefore, when a conductor pattern is formed on one surface of the substrate member 2 in the thickness direction, it can be reliably connected to the metal pin 5.

[0151] (4) In the inductor-integrated substrate 1 of the present disclosure, the coefficient of linear expansion of the substrate member 2 is 3.0 × 10 －５ The temperature is below / °C. In other words, the rate of dimensional change in the substrate material 2 with respect to temperature changes is small. As a result, displacement of the metal pins 5 due to dimensional changes in the substrate material 2 is suppressed, and the temperature reliability of the inductor-embedded substrate 1 is improved.

[0152] (5) In the inductor-integrated substrate 1 of this disclosure, the substrate member 2 is made of an insulating inorganic material. Therefore, the coefficient of linear expansion of the substrate member 2 can be reliably reduced. As a result, displacement of the metal pins 5 due to dimensional changes of the substrate member 2 is suppressed, and the temperature reliability of the inductor-integrated substrate 1 is further improved.

[0153] (6) The method for manufacturing an inductor-embedded substrate according to the present disclosure includes a placement step of inserting metal pins 5 into through holes 43, making it possible to efficiently manufacture an inductor-embedded substrate 1 with high conductivity.

[0154] 4. Modified Examples In each of the following modified examples, the same reference numerals are used for components similar to those in the above-described embodiment, and their detailed descriptions are omitted. Furthermore, each modified example can achieve the same effects and advantages as the first embodiment, unless otherwise specified. Moreover, the first embodiment and its modified examples can be combined as appropriate.

[0155] In the inductor-integrated substrate 1 of the above embodiment, the magnetic layer 4 consists of a first magnetic layer 41, but is not limited to this.

[0156] Specifically, as shown in Figure 4, in the inductor-embedded substrate 1, the magnetic layer 4 has a first magnetic layer 41 and a retaining layer 42 that holds the metal pins 5.

[0157] More specifically, the magnetic layer 4 comprises a first magnetic layer 41 that contacts the inner circumferential surface of the substrate member 2 facing the opening 21, and a retaining layer 42 that covers the outer circumferential surface of the metal pin 5. In other words, the retaining layer 42 is positioned between the first magnetic layer 41 and the metal pin 5 in the planar direction.

[0158] The outer circumferential surface of the retaining layer 42 is in contact with the inner circumferential surface of the first magnetic layer 41. Preferably, the entire outer circumferential surface of the retaining layer 42 is in contact with the inner circumferential surface of the magnetic layer 4. Also, the inner circumferential surface of the retaining layer 42 is in contact with the outer circumferential surface of the metal pin 5. Preferably, the entire inner circumferential surface of the retaining layer 42 is in contact with the outer circumferential surface of the metal pin 5.

[0159] If the magnetic layer 4 comprises a first magnetic layer 41 and a retaining layer 42 that holds the metal pin 5, the clearance between the metal pin 5 and the magnetic layer 4 can be easily adjusted. As a result, manufacturability can be improved. In particular, if the magnetic layer 4 comprises a first magnetic layer 41 that contacts the inner circumferential surface of the substrate member 2 facing the opening 21 and a retaining layer 42 that covers the metal pin 5, the clearance between the metal pin 5 and the magnetic layer 4 can be adjusted even more easily. As a result, manufacturability can be further improved.

[0160] The retaining layer 42 extends in the thickness direction. In the thickness direction, one surface and the other surface of the retaining layer 42, together with the first magnetic layer 41 and the metal pins 5, form one surface and the other surface of the inductor portion 3, respectively. In other words, in the thickness direction, one surface and the other surface of the retaining layer 42 are preferably flush with one surface and the other surface of the substrate member 2, respectively.

[0161] The shape of the retaining layer 42 is not particularly limited, and for example, it may be approximately cylindrical. If the shape of the retaining layer 42 is approximately cylindrical, the shape when viewed from the thickness direction (in plan view) is approximately annular (approximately annular in plan view).

[0162] The dimensions of the retaining layer 42 are not particularly limited. In the thickness direction, the length of the retaining layer 42 is, for example, 1 μm or more, preferably 2 μm or more, and also, for example, 50 mm or less, preferably 20 mm or less. In the thickness direction, the length of the retaining layer 42 is preferably the same as the length of the substrate member 2.

[0163] Furthermore, in the planar direction, the length of the retaining layer 42 is preferably shorter than the length of the first magnetic layer 41. The length of the retaining layer 42 is, for example, 1 μm or more, and for example, 500 μm or less.

[0164] The retaining layer 42 may include, for example, a second magnetic layer, a conductive layer, and an insulating resin layer. Preferably, the retaining layer 42 consists of at least one selected from the group consisting of a second magnetic layer, a conductive layer, and an insulating resin layer. More preferably, it consists of at least one selected from the group consisting of a second magnetic layer and a conductive layer.

[0165] The second magnetic layer contains a hardened binder and magnetic particles. Specifically, the material of the second magnetic layer can be appropriately selected from the materials described for the first magnetic layer 41 above. The material of the second magnetic layer may be the same as or different from the material of the first magnetic layer 41. Preferably, the material of the second magnetic layer is the same as the material of the first magnetic layer 41.

[0166] If the material of the second magnetic layer is the same as the material of the first magnetic layer 41, the interface between the first magnetic layer 41 and the second magnetic layer may not be observable.

[0167] The conductive layer is, for example, a metal layer. Examples of metals include copper, silver, gold, aluminum, nickel, and alloys thereof. Copper is preferred. The material of the conductive layer is preferably the same as the material of the metal pin 5.

[0168] The material for the insulating resin layer is, for example, an insulating resin. The insulating resin is not particularly limited as long as it is one that is commonly used in inductor-embedded substrates. Examples of insulating resins include polyvinyl formal, polyester, polyesterimide, polyamide (including nylon), polyimide, polyamideimide, and polyurethane.

[0169] In the above modified example of the method for manufacturing an inductor-embedded substrate, although not shown in the figures, the method further includes a retaining layer formation step, which is performed after the arrangement step and before the molding step in one embodiment of the above method for manufacturing an inductor-embedded substrate, in which a retaining layer is formed between the inner surface of the first magnetic layer 41 facing the through hole 43 and the outer surface of the metal pin 5.

[0170] In this method for manufacturing an inductor-embedded substrate, a retaining layer formation step is further included after the placement step, in which a retaining layer 42 is formed between the inner surface of the first magnetic layer 41 facing the through hole 43 and the outer surface of the metal pin 5. This allows for easy adjustment of the clearance between the outer surface of the metal pin 5 and the inner surface of the first magnetic layer 41 facing the through hole 43. As a result, manufacturability can be improved.

[0171] (Placement Process) In the modified method for manufacturing an inductor-embedded substrate, during the placement process, the metal pins 5 may be inserted such that their outer circumferential surface does not contact the inner circumferential surface of the first magnetic layer 41 facing the through hole 43, or the metal pins 5 may be inserted such that at least a portion of their outer circumferential surface contacts at least a portion of the inner circumferential surface of the first magnetic layer 41 facing the through hole 43. Preferably, the metal pins 5 are inserted such that there is a uniform gap between their outer circumferential surface and the inner circumferential surface of the first magnetic layer 41 facing the through hole 43. In other words, the outer circumferential surface of the metal pins 5 does not contact the inner circumferential surface of the first magnetic layer 41 facing the through hole 43, and a gap is formed between the outer circumferential surface of the metal pins 5 and the inner circumferential surface of the first magnetic layer 41 facing the through hole 43 in the planar direction. At this time, the maximum length of the metal pins 5 in the planar direction is smaller than the maximum length of the through hole 43.

[0172] (Retaining layer formation process) A retaining layer 42 is formed in the gap between the outer surface of the metal pin 5 and the inner surface of the first magnetic layer 41 facing the through hole 43. In other words, this is a process of forming a retaining layer 42 on the outer surface of the metal pin 5 so as to cover the metal pin 5.

[0173] Specifically, if the retaining layer 42 is the second magnetic layer, a varnish of a magnetic composition containing a binder, magnetic particles, and a solvent is filled into the above-mentioned void as the material for the second magnetic layer. Then, the magnetic composition is dried. During drying, the magnetic composition is heated if necessary. Drying removes the solvent from the magnetic composition. At this point, the magnetic composition is in a semi-cured state (stage B). Next, the magnetic composition is cured. If the binder contained in the magnetic composition is a thermosetting resin, the magnetic composition is heated. If the binder contained in the magnetic composition is a photocurable resin, the magnetic composition is irradiated with light. This causes the magnetic composition to fully cure (stage C). This forms the second magnetic layer.

[0174] Furthermore, if the retaining layer 42 is a conductive layer, a metal paste containing a metal that is the material of the conductive layer and an organic material is filled into the above-mentioned void. The metal paste is then fired. The firing conditions are not particularly limited. The conductive layer is formed by firing the metal paste. Note that the organic material is a component that is decomposed and removed by firing and does not substantially remain in the conductive layer.

[0175] Furthermore, if the retaining layer 42 is an insulating resin layer, a varnish of an insulating resin composition containing the above-mentioned insulating resin and solvent is filled into the above-mentioned voids as the material for the insulating resin layer. Then, the insulating resin composition is dried. During drying, the insulating resin composition is heated if necessary. Drying removes the solvent from the insulating resin composition. At this point, the insulating resin composition is in a semi-cured state (stage B). Next, the insulating resin composition is cured. If the insulating resin contained in the insulating resin composition is a thermosetting resin, the insulating resin composition is heated. If the insulating resin contained in the insulating resin composition is a photocurable resin, the insulating resin composition is irradiated with light. This causes the insulating resin composition to fully cure (stage C). This forms an insulating resin layer.

[0176] As a result, an inductor portion 3 is formed, consisting of a magnetic layer 4 comprising a first magnetic layer 41 and a retaining layer 42, and a metal pin 5 covering the magnetic layer 4.

[0177] Although the above invention is provided as an illustrative embodiment of this disclosure, it is merely illustrative and should not be interpreted restrictively. Modifications of this disclosure that are obvious to those skilled in the art are included in the claims below.

[0178] The inductor-integrated substrate of this disclosure is used in electronic devices (e.g., wiring circuit boards).

[0179] 1. Inductor-embedded substrate 2. Substrate component 3. Inductor section 4. Magnetic layer 5. Metal pin 21. Opening 41. First magnetic layer 42. Retaining layer

Claims

1. An inductor-embedded substrate comprising a substrate member having an opening that extends from one side in the thickness direction to the other side in the thickness direction, and an inductor portion disposed in the opening, wherein the inductor portion comprises a magnetic layer and metal pins, and the metal pins extend along the thickness direction.

2. The inductor-embedded substrate according to claim 1, wherein the magnetic layer contacts the inner circumferential surface of the substrate member facing the opening and covers the outer circumferential surface of the metal pin.

3. The inductor-embedded substrate according to claim 1, wherein in the thickness direction, one surface of the substrate member and one end surface of the metal pin are flush.

4. The inductor-embedded substrate according to claim 1, wherein the magnetic layer comprises a first magnetic layer and a retaining layer for holding the metal pins.

5. The inductor-embedded substrate according to claim 4, wherein the first magnetic layer is in contact with the inner circumferential surface of the substrate member facing the opening, and the retaining layer is disposed between the first magnetic layer and the metal pin in a planar direction perpendicular to the thickness direction, and covers the outer circumferential surface of the metal pin.

6. The inductor-embedded substrate according to claim 4, wherein the retaining layer comprises at least one selected from the group consisting of a second magnetic layer, a conductive layer, and an insulating resin layer.

7. The coefficient of linear expansion of the substrate material is 3.0 × 10 －５ An inductor-embedded substrate according to any one of claims 1 to 6, wherein the temperature is below / ℃.

8. The inductor-embedded substrate according to any one of claims 1 to 6, wherein the substrate member is made of an insulating inorganic material.

9. A method for manufacturing an inductor-embedded substrate, comprising: a preparation step of preparing a substrate member having an opening that extends from one side in the thickness direction to the other side in the thickness direction; a first magnetic layer forming step of forming a first magnetic layer in the opening; a through hole forming step of forming a through hole that penetrates from one side in the thickness direction to the other side in the thickness direction of the first magnetic layer; and a placement step of inserting a metal pin into the through hole.

10. The method for manufacturing an inductor-embedded substrate according to claim 9, further comprising a retaining layer forming step, after the arrangement step, of forming a retaining layer between the inner surface of the first magnetic layer facing the through hole and the outer surface of the metal pin.

11. The method for manufacturing an inductor-embedded substrate according to claim 10, wherein the retaining layer comprises at least one selected from the group consisting of a second magnetic layer, a conductive layer, and an insulating resin layer.

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