Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F17/00—Fixed inductances of the signal type
  • H01F17/04—Fixed inductances of the signal type with magnetic core
  • H01F17/06—Fixed inductances of the signal type with magnetic core with core substantially closed in itself, e.g. toroid
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F17/00—Fixed inductances of the signal type
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F17/00—Fixed inductances of the signal type
  • H01F17/0006—Printed inductances
  • H01F17/0013—Printed inductances with stacked layers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F17/00—Fixed inductances of the signal type
  • H01F17/04—Fixed inductances of the signal type with magnetic core
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
  • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
  • H01F41/04—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing coils
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
  • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
  • H01F41/04—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing coils
  • H01F41/041—Printed circuit coils
  • H01F41/046—Printed circuit coils structurally combined with ferromagnetic material
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
  • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
  • H01F41/04—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing coils
  • H01F41/06—Coil winding
  • H01F41/061—Winding flat conductive wires or sheets
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
  • H10W70/00—Package substrates; Interposers; Redistribution layers [RDL]
  • H10W70/60—Insulating or insulated package substrates; Interposers; Redistribution layers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F17/00—Fixed inductances of the signal type
  • H01F17/04—Fixed inductances of the signal type with magnetic core
  • H01F2017/048—Fixed inductances of the signal type with magnetic core with encapsulating core, e.g. made of resin and magnetic powder

Definitions

• the present invention relates to an inductor and its manufacturing method.
• An inductor that has a substrate having a through hole, a conductive portion disposed inside the through hole, and a magnetic layer disposed between the inner surface of the through hole and the outer surface of the conductive portion (for example, See Patent Document 1 below.).
• Inductors are required to have high inductance and sufficient DC superposition characteristics.
• the magnetic material is formed only on the side surfaces of the conductive portion. Therefore, there is a limit to satisfying high inductance and sufficient DC superposition characteristics.
• the conductive part can be easily formed while increasing the degree of freedom in the arrangement of the conductive part.
• the present invention can manufacture an inductor having high inductance and sufficient DC superimposition characteristics, and an inductor having high inductance and sufficient DC superimposition characteristics, while increasing the degree of freedom in arranging the conductive parts.
• a method for manufacturing an inductor that can be easily formed.
• the present invention [1] comprises a step of curing a curable sheet containing a curable resin and magnetic particles to form a magnetic sheet extending in a direction orthogonal to a thickness direction, and forming through holes in the magnetic sheet. a step of opening toward one side and the other side of the magnetic sheet in the thickness direction and forming along the thickness direction; and forming a conductive portion in the through hole along the thickness direction of the magnetic sheet. and a method of manufacturing an inductor.
• the magnetic sheet extends in the plane direction orthogonal to the thickness direction. That is, the magnetic sheet has a large area in the planar direction. Then, a through-hole can be formed at an arbitrary position in the magnetic sheet, and then a conductive portion can be formed in the through-hole. Therefore, it is possible to easily form the conductive portion while increasing the degree of freedom in arranging the conductive portion.
• the magnetic sheet extends in the plane direction, it is possible to improve the inductance and DC superimposition characteristics of the inductor.
• the present invention [2] provides the inductor according to [1], wherein in the step of forming the through holes, the magnetic sheet is processed by at least one selected from the group consisting of drilling, blasting, and dicing. Including manufacturing method.
• the magnetic sheet in the step of forming the through holes, is processed by at least one selected from the group consisting of drilling, blasting, and dicing. can be easily formed.
• the present invention [3] further comprises the step of forming an insulating layer on the inner peripheral surface of the magnetic sheet facing the through hole, and in the step of forming the conductive portion, forming the conductive portion on the inner peripheral surface of the insulating layer. It includes the method of manufacturing the inductor according to [1] or [2], which is arranged on a surface.
• the inductor further includes an insulating layer arranged between the inner peripheral surface of the magnetic sheet and the outer peripheral surface of the conductive portion, so that the conductive portion can be reliably insulated from the magnetic sheet.
• the step of forming the conductive portion includes the step of forming a base on the inner peripheral surface of the insulating layer and at least one surface of the magnetic sheet in the thickness direction [3]. including the method of manufacturing the inductor described in .
• the base can function as a connection pad.
• the step of forming the conductive portion includes, after the step of forming the base, filling the inside of the base with a conductive paste and firing the conductive paste to form the main body.
• the main body can be easily formed because the conductive paste is filled inside the base.
• the curable sheet contains a resin component, the resin component contains an epoxy resin and a phenol resin contained in the curable resin, and an acrylic resin, and is 25% by volume or more and 60% by volume or less, the method for manufacturing an inductor according to any one of [1] to [5].
• the resin component in the curable sheet contains an epoxy resin, a phenol resin, and an acrylic resin, and the content of the acrylic resin in the resin component is 25% by volume or more and 60% by volume or less. can impart high workability to the magnetic sheet.
• the present invention [7] is the inductor [6], wherein the epoxy resin consists only of an epoxy resin having three or more functional groups, and the phenol resin consists only of a phenol resin having three or more functional groups. Including manufacturing method.
• the epoxy resin having three or more functional groups is a cresol novolac type epoxy resin
• the phenolic resin having three or more functional groups is a phenol biphenylene resin [7]. including the method of manufacturing the inductor described in .
• the present invention [9] includes the method of manufacturing an inductor according to [1] or [2], characterized in that the step of forming the through holes is performed after the step of curing the curable sheet. .
• Forming through holes in a curable sheet before heat curing makes it difficult to control the shape considering the thermal shrinkage of the curable resin, cracks occur in the curable sheet after curing, and the processing difficulty of the curable sheet. becomes higher.
• the present invention is a magnetic sheet having through holes that open toward one side and the other side in the thickness direction, the through holes extending along the thickness direction, and extending in a direction orthogonal to the thickness direction. and an inductor including a magnetic sheet containing a cured resin and magnetic particles, and a conductive portion filled in the through hole and extending along the thickness direction of the magnetic sheet.
• the magnetic sheet since the magnetic sheet extends in the plane direction perpendicular to the thickness direction, it can have high inductance and sufficient DC superimposition characteristics.
• the magnetic layer described in Patent Document 1 cannot have high inductance and sufficient DC superimposition characteristics because it is arranged only on the side surface of the conductive portion inside the through hole.
• the inductor of the present invention can have higher inductance and sufficient DC superimposition characteristics than the inductor of Patent Document 1.
• the present invention [11] includes the inductor according to [10], further comprising an insulating layer arranged between the inner peripheral surface of the magnetic sheet facing the through hole and the outer peripheral surface of the conductive portion.
• this inductor further includes an insulating layer arranged between the inner peripheral surface of the magnetic sheet and the outer peripheral surface of the conductive portion, the conductive portion can be reliably insulated from the magnetic sheet.
• the conductive part includes a base arranged inside the insulating layer and at least one side of the magnetic sheet in the thickness direction, and a main body arranged inside the base. , including the inductor described in [11].
• the base can function as a connection pad.
• an inductor of the present invention it is possible to manufacture an inductor with high inductance, increase the degree of freedom in arranging the conductive part, and easily form the conductive part.
• the inductor of the present invention has high inductance and sufficient DC superposition characteristics.
• FIG. 1A is a plan view of one embodiment of the inductor of the present invention.
• FIG. 1B is a cross-sectional view along line XX of FIG. 1A.
• FIG. 2A is a step of forming a curable sheet.
• FIG. 2B is a step of curing the curable sheet.
• FIG. 2C is a step of forming through holes.
• FIG. 2D is a step of forming an insulating layer.
• FIG. 3E is a step of forming a base.
• FIG. 3F is a step of arranging the conductive paste in the through holes.
• FIG. 3G is a step of firing the conductive paste.
• FIG. 3H is a step of removing unnecessary portions of the underlayer.
• the inductor 1 has a thickness.
• the inductor 1 has a sheet shape.
• the inductor 1 extends along the surface direction.
• the plane direction is perpendicular to the thickness.
• the inductor 1 includes a magnetic sheet 2, a conductive portion 3, and an insulating layer 4 (see FIG. 1B).
• the magnetic sheet 2 extends in a surface direction (an example of a direction perpendicular to the thickness direction).
• the magnetic sheet 2 has one side 2SA and the other side 2SB facing each other in the thickness direction.
• the magnetic sheet 2 further has through holes 21 .
• Through hole 21 extends along the thickness direction. Through hole 21 opens toward one side and the other side in the thickness direction. In this embodiment, the through hole 21 has a substantially circular shape when viewed in the thickness direction. In this embodiment, the plurality of through-holes 21 are aligned and spaced from each other in the planar direction.
• the magnetic sheet 2 has an inner peripheral surface 2S facing the through hole 21 described above.
• the magnetic sheet 2 contains a resin component and magnetic particles.
• the resin component is a resin matrix that disperses the magnetic particles in the magnetic sheet 2 .
• the resin component contains at least a cured resin.
• a cured resin is a cured product (cured body) of a curable resin.
• curable resins include thermosetting resins and photocurable resins, preferably thermosetting resin compositions.
• a curable resin is prepared, for example, as a resin composition.
• the resin composition contains, for example, a main agent, a curing agent and a curing accelerator. Resin compositions are described, for example, in JP-A-2020-150057, JP-A-2020-150063, and JP-A-2020-150066.
• the proportion of the cured resin in the magnetic sheet 2 is, for example, 5% by volume or more, preferably 10% by volume or more, and is, for example, 60% by volume or less, preferably 50% by volume or less.
• Magnetic particles include, for example, soft magnetic particles.
• Soft magnetic particles are described, for example, in JP-A-2020-150057, JP-A-2020-150063, and JP-A-2020-150066.
• the magnetic particles do not include hard magnetic particles.
• the hard magnetic particles contain ferrite. If the magnetic particles contain hard magnetic particles, the core will have a high coercive force, which is not suitable for the present invention.
• the ratio of the magnetic particles to 100 parts by mass of the cured resin is, for example, 400 parts by mass or more, preferably 500 parts by mass or more, and is, for example, 4000 parts by mass or less, preferably 3500 parts by mass or less.
• the ratio of the magnetic particles in the magnetic sheet 2 is, for example, 25% by volume or more, preferably 30% by volume or more, and is, for example, 75% by volume or less, preferably 70% by volume or less.
• the thickness T1 of the magnetic sheet 2 is, for example, 1 ⁇ m or more, preferably 2 ⁇ m or more, and is, for example, 20 mm or less, preferably 10 mm or less.
• the thickness T1 of the magnetic sheet 2 corresponds to the length of the through holes 21 in the thickness direction.
• the maximum length of the through-holes 21 when viewed in the thickness direction is, for example, 1 ⁇ m or more, preferably 10 ⁇ m or more, and is, for example, 100 mm or less, preferably 50 mm or less.
• the maximum length described above corresponds to the diameter of the through-hole 21 .
• the interval between adjacent through holes 21 is, for example, 1 ⁇ m or more, preferably 2 ⁇ m or more, and is, for example, 100 mm or less, preferably 50 mm or less.
• the conductive portion 3 mainly has a portion filled in the through hole 21 .
• the conductive portion 3 extends along the thickness direction of the magnetic sheet 2 .
• the conductive portion 3 has a substantially T-shape in a cross-sectional view.
• the conductive portion 3 is provided corresponding to each of the plurality of through holes 21 .
• each of the multiple conductive parts 3 includes a base 31 and a main body 32 .
• the underlayer 31 is arranged inside the through hole 21 and on one side of the magnetic sheet 2 .
• the base 31 functions as a base for the main body 32 .
• the underlayer 31 has a substantially hat shape in a cross-sectional view along the thickness direction.
• the base 31 has a first portion 311 and a second portion 312 .
• the first part 311 is arranged inside the through hole 21 .
• the first portion 311 has a substantially cylindrical shape.
• the first part 311 extends along the thickness direction.
• the first portion 311 forms the outer peripheral surface 3S of the conductive portion 3 .
• the second portion 312 is positioned at one end of the substrate 31 in the thickness direction.
• the second part 312 is continuous with the first part 311 .
• the second portion 312 extends outward from one edge of the first portion 311 in the thickness direction.
• the second portion 312 has a substantially annular shape when viewed in the thickness direction.
• the second part 312 corresponds to the brim of the hat.
• the second part 312 can form a connection pad together with one side of the first part 311 in the thickness direction.
• the main body 32 is filled inside the first portion 311 .
• the main body 32 is in contact with the inner peripheral surface of the first portion 311 of the base 31 .
• the main body 32 is the main part of the conductive part 3 .
• the main body 32 extends along the thickness direction of the magnetic sheet 2 .
• the body 32 is cylindrical.
• the axis of the cylinder runs along the thickness direction.
• Conductive Portion 3 As a material of the conductive portion 3, a conductive material can be used. Conductive materials include, for example, gold, silver, copper, and alloys. The materials of substrate 31 and body 32 may be different or the same.
• the thickness of the base 31 is, for example, 5 nm or more, preferably 10 nm or more, and is, for example, 100 ⁇ m or less, preferably 50 ⁇ m or less.
• the thickness of the base 31 is the thickness of each of the first portion 311 and the second portion 312 .
• the thickness of the first portion 311 is the thickness in the radial direction.
• the thickness of the second portion 312 is the length in the thickness direction.
• the length of the main body 32 in the thickness direction is, for example, 1 ⁇ m or more, preferably 2 ⁇ m or more, and is, for example, 20 mm or less, preferably 10 mm or less.
• the maximum length of the main body 32 is, for example, 1 ⁇ m or more, preferably 10 ⁇ m or more, and is, for example, 100 mm or less, preferably 50 mm or less.
• the maximum length of the main body 32 corresponds to the diameter of the main body 32 .
• the ratio of the thickness of the substrate 31 to the maximum length of the main body 32 is, for example, 1 or less, preferably 0.1 or less, and, for example, 5 ⁇ 10 -8 or more, preferably 1 ⁇ 10 - 7 or more.
• a boundary may be clearly observed between the base 31 and the main body 32. Further, as shown in FIG. 1B, in the conductive portion 3, the boundary, the base 31 and the main body 32 are unclear and may not be observed.
• the insulating layer 4 has a function of insulating the conductive portion 3 from the magnetic sheet 2 .
• the insulating layer 4 is provided corresponding to each of the plurality of through holes 21 and each of the plurality of conductive portions 3 .
• Each of the plurality of insulating layers 4 has a third portion 41 and a fourth portion 42 .
• the third portion 41 is arranged between the inner peripheral surface 2S of the magnetic sheet 2 and the outer peripheral surface 3S of the conductive portion 3 (first portion 311).
• the third portion 41 has a substantially cylindrical shape. The axis of the cylinder runs along the thickness direction.
• the fourth part 42 is arranged on one side of the magnetic sheet 2 in the thickness direction and on one side of the third part 41 in the thickness direction.
• the fourth portion 42 extends in the planar direction.
• Materials for the insulating layer 4 include insulating resins and insulating inorganic materials.
• Insulating resins include, for example, epoxies, acrylics, polyesters, polyurethanes, polyesterimides, polyamideimides, and polyimides.
• Insulating inorganic materials include, for example, silica, alumina, zirconia, titanium oxide, magnesium oxide, tin oxide, tantalum oxide, and silicon nitride.
• the thickness of the insulating layer 4 is, for example, 0.01 ⁇ m or more and, for example, 100 ⁇ m or less.
• the thickness of insulating layer 4 includes the thickness of third portion 41 and the thickness of fourth portion 42 .
• This manufacturing method comprises a step of forming the magnetic sheet 2, a step of forming the through hole 21 in the magnetic sheet 2, a step of forming the insulating layer 4 in the magnetic sheet 2, and a step of forming the conductive portion 3 in the through hole 21. and a step.
• Step of Forming Magnetic Sheet 2 In the step of forming the magnetic sheet 2, first, a curable sheet 2C is formed as shown in FIG. 2A.
• the curable sheet 2C contains a resin component and magnetic particles.
• the resin component contains a curable resin and a thermoplastic resin.
• Curable resins include epoxy resins and phenolic resins.
• the thermoplastic resin contains acrylic resin. In other words, the resin component contains epoxy resin, phenolic resin, and acrylic resin.
• Epoxy resins are epoxy resins (multifunctional epoxy resins) that have three or more functional groups in the molecule.
• Functional groups include, for example, a glycidyl group.
• polyfunctional epoxy resins include phenol novolak-type epoxy resins, cresol novolak-type epoxy resins, trishydroxyphenylmethane-type epoxy resins, and tetraphenylolethane-type epoxy resins.
• phenol novolak-type epoxy resins cresol novolak-type epoxy resins
• trishydroxyphenylmethane-type epoxy resins tetraphenylolethane-type epoxy resins.
• tetraphenylolethane-type epoxy resins tetraphenylolethane-type epoxy resins.
• the epoxy resin preferably consists only of epoxy resins having three or more functional groups. In other words, the epoxy resin in the resin component does not substantially contain epoxy resins having two functional groups.
• Phenolic resin is a curing agent for epoxy resin.
• a phenolic resin is a phenolic resin having three or more functional groups in the molecule (polyfunctional phenolic resin).
• the functional group preferably includes a hydroxyl group.
• polyfunctional phenol resins examples include phenol novolac resins, cresol novolac resins, phenol aralkyl resins, phenol biphenylene resins, dicyclopentadiene type phenol resins, and resole resins.
• Phenol biphenylene resin is preferably used as the polyfunctional phenol resin.
• the phenolic resin preferably consists only of phenolic resins having three or more functional groups. In other words, the phenolic resin in the resin component does not substantially contain phenolic resins having two functional groups.
• Contains substantially no bifunctional phenolic resin means that the content of the phenolic resin having two functional groups in the total phenolic resin is, for example, 1.0% by weight or less, preferably 0.5% by weight. Hereinafter, more preferably, it means 0% by mass.
• the acrylic resin includes, for example, an acrylic polymer obtained by polymerizing one or more of (meth)acrylic acid alkyl esters having a linear or branched alkyl group as a monomer component. are mentioned.
• (meth)acryl represents "acryl and/or methacryl”.
• alkyl groups include alkyl groups having 1 to 20 carbon atoms.
• alkyl groups having 1 to 20 carbon atoms include methyl, ethyl, propyl, isopropyl, n-butyl, t-butyl, isobutyl, amyl, isoamyl, hexyl, heptyl, cyclohexyl, 2-ethylhexyl, octyl, isooctyl, Nonyl, isononyl, decyl, isodecyl, undecyl, lauryl, tridecyl, tetradecyl, stearyl, octadecyl and dodecyl.
• the alkyl group preferably includes an alkyl group having 1 to 6 carbon atoms.
• the acrylic polymer may be a copolymer of a (meth)acrylic acid alkyl ester and other monomers.
• Other monomers include, for example, glycidyl group-containing monomers, carboxyl group-containing monomers, acid anhydride monomers, hydroxyl group-containing monomers, sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, styrene monomers, and acrylonitrile.
• Glycidyl group-containing monomers include, for example, glycidyl acrylate and glycidyl methacrylate.
• Carboxyl group-containing monomers include, for example, acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid.
• Anhydride monomers include, for example, maleic anhydride and itaconic anhydride.
• hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate. , 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)-methyl acrylate.
• sulfonic acid group-containing monomers examples include styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and ( meth)acryloyloxynaphthalenesulfonic acid.
• Phosphate group-containing monomers include, for example, 2-hydroxyethyl acryloyl phosphate. These can be used alone or in combination of two or more.
• the acrylic resin preferably has at least one group of a carboxy group and a hydroxyl group. More preferably, a carboxy group and a hydroxyl group are used in combination. As a result, it is possible to more reliably suppress the generation of air gaps and improve the magnetic properties.
• the acrylic resin content in the resin component is 25% by volume or more, preferably 30% by volume or more, more preferably 35% by volume or more, and is, for example, 80% by volume or less, preferably 70% by volume. Below, more preferably 60% by volume or less.
• the content of the acrylic resin is within the above range, the magnetic sheet 2 can be provided with high workability when the through holes 21 are formed.
• the content of the acrylic resin is within the above range, the springback of the magnetic sheet 2 can be suppressed.
• the resin component may further contain a curing accelerator.
• Curing accelerators include, for example, imidazole compounds.
• varnish is applied to form a coating film as indicated by the phantom lines in FIG. 2A.
• a varnish contains a resin composition, magnetic particles, and a solvent.
• An example of the formulation of the resin composition is shown in Table 1 below.
• the curable sheet 2C is a sheet before complete curing, specifically a B-stage sheet or an A-stage sheet.
• the A stage is a state in which the curable resin is liquid.
• the curable resin is in a state between the above-described A stage and the completely cured C stage. It is in a state smaller than the compressive elastic modulus of the stage.
• the curable sheet 2C is then cured. If the curable resin is a thermosetting resin, the curable sheet 2C is heated. If the curable resin is a photocurable resin, the curable sheet 2C is irradiated with light. As a result, the curable resin is completely cured (C-staged). Thereby, the magnetic sheet 2 containing the cured product (cured body) of the curable resin is formed.
• the curable resin is a thermosetting resin
• the curable sheet 2C is heated. If the curable resin is a photocurable resin, the curable sheet 2C is irradiated with light. As a result, the curable resin is completely cured (C-staged). Thereby, the magnetic sheet 2 containing the cured product (cured body) of the curable resin is formed.
• This magnetic sheet 2 does not yet have through holes 21 .
• through holes 21 are formed as shown in FIG. 2C. That is, the step of forming the through holes 21 (see FIG. 2C) is performed after the step of curing the magnetic sheet 2 (see FIG. 2B).
• the magnetic sheet 2 is processed by at least one selected from the group consisting of drilling, blasting, and dicing.
• dry etching can be used in addition to the above.
• at least one selected from the group consisting of drilling, blasting, and dicing. The above-described one is advantageous in comparison with dry etching because the through hole 21 can be easily formed at an arbitrary position on the magnetic sheet 2 .
• the insulating layer 4 is formed on the inner peripheral surface 2S and one surface 2SA of the magnetic sheet 2 .
• the insulating layer 4 is formed, for example, by photolithography. Specifically, a release film (not shown) is placed on the other surface of the magnetic sheet 2 , and then a photosensitive insulating resin composition is applied to one surface of the release film and the inner peripheral surface 2 ⁇ /b>S of the magnetic sheet 2 . and one surface 2SA, and then the third part 41 and the fourth part 42 are formed by photolithography.
• the process of forming the conductive portion 3 includes a process of forming a base 31 (see FIG. 3E), a process of forming a main body 32 (see FIG. 3G), and a process of removing an unnecessary portion 30 of the base 31 (see FIG. 3H). and including.
• the underlayer 31 is formed on the inner peripheral surface of the insulating layer 4 and one surface of the insulating layer 4 in the thickness direction.
• the first portion 311 is formed on the inner peripheral surface of the third portion 41 of the insulating layer 4, and the second portion 312 is formed on one surface of the fourth portion 42 in the thickness direction.
• Sputtering or plating is used in the step of forming the underlayer 31 . Examples of plating include electroless plating. Thereby, the first part 311 and the second part 312 are formed at the same time.
• the second portion 312 formed in this step is formed on the entire one surface of the fourth portion 42 of the insulating layer 4 .
• the second portion 312 includes the garbage portion 30 .
• the unnecessary portion 30 is a portion other than the second portion 312 when viewed in the thickness direction, and is a portion not included in the base 31 of the inductor 1 (see FIG. 3H) as a product.
• a conductive paste 3P is filled inside the base 31 (see FIG. 3F), and then such a conductive paste is applied.
• Firing paste 3P (see FIG. 3G).
• a conductive paste 3 ⁇ /b>P is placed on the inner peripheral surface of the first portion 311 of the base 31 .
• the conductive paste 3P is not arranged on one side of the second portion 312 in the thickness direction.
• one surface of the conductive paste 3P in the thickness direction is arranged on one side of the one surface of the second portion 312 in the thickness direction. That is, the one surface of the conductive paste 3P rises to one side in the thickness direction with respect to the one surface of the second portion 312 .
• the conductive paste includes the above-mentioned conductive materials and organic materials.
• Examples of the shape of the conductive material include a particle shape.
• the organic material is a component that is decomposed and removed by baking, which will be described below, and is a component that does not substantially remain in the conductive portion 3 .
• the conductive paste 3P is then fired. Firing conditions are not limited.
• the main body 32 is formed by firing the conductive paste 3P. In this embodiment, one surface of the main body 32 and one surface of the second portion 312 are flush with each other.
• etching is used in the step of removing the unnecessary portion 30 of the underlayer 31, for example, etching is used.
• a second portion 312 of the underlayer 31 is formed by removing the unnecessary portion 30 . That is, the underlayer 31 composed of the first portion 311 and the second portion 312 is formed.
• the conductive portion 3 having the base 31 and the main body 32 is formed.
• the through holes 21 can be formed in the magnetic sheet 2 as shown in FIG. 2C, and then the conductive portions 3 can be formed in the through holes 21 as shown in FIG. 3H. Therefore, it is possible to easily form the conductive portion 3 while increasing the degree of freedom of arrangement of the conductive portion 3 .
• the magnetic sheet 2 extends in the plane direction, the inductance of the inductor 1 can be increased, and the DC superimposition characteristics can also be improved.
• the magnetic sheet 2 is processed by at least one selected from the group consisting of drilling, blasting, and dicing.
• the through hole 21 can be easily formed at any position on the sheet 2 .
• the second portion 312 of the base 31 is formed on the one surface 2SA of the magnetic sheet 2 in the thickness direction, so that the second portion 312 can function as a connection pad. .
• the main body 32 of the base 31 can be easily formed.
• the resin component in the curable sheet 2C contains the epoxy resin, the phenol resin, and the acrylic resin, and the content of the acrylic resin in the resin component is 25% by volume. % or more and 60 volume % or less, high workability can be imparted to the magnetic sheet 2 when the through holes 21 are formed.
• the magnetic sheet 2 extends in the plane direction, so the inductance can be increased and the DC superimposition characteristics are also excellent.
• the magnetic layer described in Patent Document 1 cannot have high inductance and sufficient DC superimposition characteristics because it is arranged only between the substrate and the conductive portion inside the through hole.
• the inductor 1 of this embodiment can have high inductance and excellent DC superimposition characteristics as compared with the inductor of Patent Document 1.
• the inductor 1 further includes an insulating layer 4 arranged between the inner peripheral surface 2S of the magnetic sheet 2 and the outer peripheral surface 3S of the conductive portion 3, the conductive portion 3 can be reliably insulated from the magnetic sheet 2.
• the base 31 can function as a connection pad.
• the insulating layer 4 can also be arranged on the other side of the conductive portion 3 in the thickness direction.
• the conductive part 3 can also be provided with only the main body 32 without the base 31 .
• the base 31 can also be arranged on the other side of the magnetic sheet 2 in the thickness direction.
• a step of forming through-holes may be performed before the step of hardening the magnetic sheet 2 . That is, the through holes 21 are formed in the curable sheet 2C, and then the curable sheet 2C is cured.
• the degree of difficulty in processing increases. For example, it is difficult to control the shape of the through-holes in consideration of the heat shrinkage of the curable resin, or cracks occur in the curable sheet 2C after curing. It is difficult to form with high accuracy.
• the step of forming the through holes 21 is performed after the step of curing the curable sheet 2C (see FIG. 2B). Therefore, it is possible to stably process the magnetic sheet 2 after thermosetting while maintaining good filling properties of the magnetic particles, that is, while maintaining good magnetic properties. Therefore, the magnetic sheet 2 having the through-holes 21 is excellent in processing stability while forming the through-holes 21 with high accuracy.
• the manufacturing method is used to manufacture inductors.

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• 2023
  • 2023-02-14 WO PCT/JP2023/004978 patent/WO2023157833A1/ja not_active Ceased
  • 2023-02-14 US US18/837,113 patent/US20250149225A1/en active Pending
  • 2023-02-14 JP JP2024501380A patent/JPWO2023157833A1/ja active Pending
  • 2023-02-16 TW TW112105521A patent/TW202341194A/zh unknown

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