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
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F27/00—Details of transformers or inductances, in general
  • H01F27/28—Coils; Windings; Conductive connections
  • H01F27/29—Terminals; Tapping arrangements for signal inductances
• • 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
  • H01F5/00—Coils
  • H01F5/04—Arrangements of electric connections to coils, e.g. leads

Definitions

• the disclosures herein relate to inductor member manufacturing methods and inductor members.
• An inductor member is used as a circuit element mounted in various electronic devices. Moreover, a sheet-like inductor member including an interconnect and a magnetic layer in which the interconnect is embedded is disclosed (see, e.g., Patent Literature (PTL) 1).
• PTL Patent Literature
• the inductor member disclosed in PTL 1 includes a plurality of interconnects spaced adjacent to each other.
• a hole such as a via hole is formed penetrating from one surface in a thickness direction of the magnetic layer and configured to accommodate a conductive member.
• the present disclosure provides an inductor member manufacturing method with high machining accuracy.
• a method for manufacturing an inductor member includes a first process of manufacturing a magnetic structure including at least two interconnects each having a conducting core and an insulating film covering a peripheral surface of the conducting core and being disposed at different positions in a first direction, and a magnetic layer in which the at least two interconnects are embedded, a second process of forming at least two first holes by using a routing method or a drilling method, each of the at least two first holes being connected to a different one of the at least two interconnects, a third process of forming a first protrusion of insulating property inside each of the at least two first holes, a fourth process of forming a second hole penetrating the first protrusion, and a fifth process of forming a second protrusion of conductive property in the second hole, the second protrusion being connected to the conducting core of a corresponding one of the interconnects.
• machining accuracy of the inductor member can be increased.
• FIG. 1 is a plan view of the inductor member manufactured with the inductor member manufacturing method according to the first embodiment.
• FIG. 2 is an A-A cross-sectional view of FIG. 1 .
• FIG. 3 is a B-B cross-sectional view of FIG. 1 .
• An X-direction shown in the figure corresponds to the width direction of the inductor member 1.
• a Y-direction corresponds to the horizontal depth direction of the inductor member 1.
• a Z-direction corresponds to the thickness direction of the inductor member 1.
• the X-direction and the Y-direction may be referred to as an "in-plane direction" of the inductor member 1.
• the Z-direction may be referred to as an "out-of-plane direction" of the inductor member 1.
• the X-direction, the Y-direction and the Z-direction are mutually orthogonal.
• the inductor member 1 is a sheet-like member having a rectangular planar shape. More specifically, the inductor member 1 includes a magnetic laminate 10, a plurality of interconnects 20, a terminal pair 30 having a first terminal part 31 and a second terminal part 32, and an insulating film 40.
• the magnetic laminate 10 is an example of a "magnetic layer”.
• a number of interconnects 20 is two in FIGS. 1 to 3 , but the number may be three or more.
• the first terminal part 31 and the second terminal part 32 are examples of "terminal parts".
• the insulating film 40 may be provided as needed.
• the magnetic laminate 10 has a rectangular planar shape. As shown in FIGS. 2 and 3 , the magnetic laminate 10 has a front surface 10S located on one side in the Z-direction and a back surface 10B located on the other side in the Z-direction. Each of the front surface 10S and the back surface 10B of the magnetic laminate 10 of the first embodiment is covered with the insulating film 40.
• the front surface 10S of the magnetic laminate 10 is an example of a "first surface" of the magnetic layer.
• the back surface 10B of the magnetic laminate 10 is an example of a "second surface" of the magnetic layer.
• the magnetic laminate 10 preferably has a plurality of magnetic layers from the viewpoint of enhancing inductance values and DC superposition characteristics. More specifically, the magnetic laminate 10 has a first magnetic layer 11, a second magnetic layer 12 disposed on one side of the first magnetic layer 11 in the Z-direction, and a third magnetic layer 13 disposed on the other side of the first magnetic layer 11 in the Z-direction. The first magnetic layer 11 is disposed between the second magnetic layer 12 and the third magnetic layer 13.
• the second magnetic layer 12 corresponds to the uppermost layer of the magnetic laminate 10. Therefore, the front surface 10S of the magnetic laminate 10 corresponds to the front surface 121 located on one side of the second magnetic layer 12 in the Z-direction.
• the third magnetic layer 13 corresponds to the lowermost layer of the magnetic laminate 10. Therefore, the back surface 10B of the magnetic laminate 10 corresponds to the back surface 131 located on the other side of the third magnetic layer 13 in the Z-direction.
• the magnetic laminate 10 does not necessarily include a plurality of magnetic layers. That is, the magnetic laminate 10 may consist, for example, of a monolayer structure including only the first magnetic layer 11.
• the first magnetic layer 11 has a predetermined thickness in the Z-direction and has a sheet-like form extending in the in-plane direction. As shown in FIGS. 2 and 3 , a plurality of interconnects 20 are embedded in the first magnetic layer 11.
• the first magnetic layer 11 includes magnetic particles and a binder holding the magnetic particles.
• shapes of the magnetic particles include an approximately spherical shape, an approximately needle shape, and an approximately flat shape, but are not limited thereto.
• Examples of materials of the magnetic particles in the first magnetic layer 11 include soft magnetic materials and hard magnetic materials, but are not limited thereto. Among them, soft magnetic materials are preferable from the viewpoint of improving the inductance and DC superposition characteristics of the inductor member 1.
• soft magnetic materials include a single metal body containing one type of metallic element in a state of a pure substance, and an alloy body which is a eutectic body (mixture) of one or more types of metallic elements (first metallic element) and one or more types of metallic elements (second metallic element) and/or non-metallic elements (carbon, nitrogen, silicon, phosphorus, etc.). These materials can be used alone or in combination.
• Examples of single metal bodies include a single metal material consisting of only one type of metallic element (first metallic element).
• first metallic elements include iron (Fe), cobalt (Co), nickel (Ni), and other metallic elements which can be contained as the first metallic element of the soft magnetic material.
• single metal bodies include: a form including a core containing only one metallic element and a surface layer that includes an inorganic and/or organic substance modifying a part or entirety of the surface of the core; and a form obtained by decomposition (thermal decomposition, etc.) of an organometallic or inorganic metal compound containing a first metallic element.
• forms in which an organometallic or inorganic metal compound containing a first metal element is decomposed include iron powder (may be referred to as carbonyl iron powder) obtained by thermal decomposition of an organic iron compound (specifically, pentacarbonyl iron) containing iron as the first metal element.
• a position of a layer containing an inorganic and/or organic substance that modifies a portion containing only one metallic element is not limited to the surface described above.
• An organometallic or inorganic metal compound for obtaining a single metal body is not particularly limited, and can be appropriately selected from any known or commonly used organometallic or inorganic metal compound capable of yielding a soft magnetic single metal body.
• the alloy body 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 (carbon, nitrogen, silicon, phosphorus, etc.), and is not particularly limited as long as it can be used as an alloy body of a soft magnetic body.
• the first metallic element is an essential element in the alloy body, such as iron (Fe), cobalt (Co), and nickel (Ni). Note that, when the first metallic element is Fe, the alloy body is considered as an Fe-based alloy, when the first metallic element is Co, the alloy body is considered as a Co-based alloy, and when the first metallic element is Ni, the alloy body is considered as a Ni-based alloy.
• the second metallic element is an element (sub-component) secondarily contained in the alloy body and is a metallic element that is compatible (eutectic) with the first metallic element, such as iron (Fe) (when the first metallic element is other than Fe), cobalt (Co) (when the first metallic element is other than Co), nickel (Ni) (when the first metallic element is other than Ni), chromium (Cr), aluminum (Al), silicon (Si), copper (Cu), silver (Ag), manganese (Mn), calcium (Ca), barium (Ba), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), molybdenum (Mo), tungsten (W), ruthenium (Ru), rhodium (Rh), zinc (Zn), gallium (Ga), indium (In), germanium (Ge), tin (Sn), lead (Pb), scandium (Sc), y
• the non-metallic element is an element (sub-component) that is contained in the alloy body as a secondary component and is a non-metallic element that is compatible (eutectic) with the first metallic element, such as boron (B), carbon (C), nitrogen (N), silicon (Si), phosphorus (P), and sulfur (S). These elements can be used alone or in combination with two or more of them.
• Fe-based alloys which are a type of alloy body, include magnetic stainless steel (Fe-Cr-Al-Si alloy) (including electromagnetic stainless steel), Sendust (Fe-Si-Al alloy) (including Super Sendust), permalloy (Fe-Ni alloy), Fe-Ni-Mo alloy, Fe-Ni-Mo-Cu alloy, Fe-Ni-Co alloy, Fe-Cr alloy, Fe-Cr-Al alloy, Fe-Ni-Cr alloy, Fe-Ni-Cr-Si alloy, silicon copper (Fe-Cu-Si alloy), Fe-Si alloy, Fe-Si-B(-Cu-Nb) alloy, Fe-B-Si-Cr alloy, Fe-Si-Cr-Ni alloy, Fe-Si-Cr alloy, Fe-Si-Al-Ni-Cr alloy, Fe-Ni-Si-Co alloy, Fe-N alloy, Fe-C alloy, Fe-B alloy, Fe-P alloy, ferrite (including
• Co-based alloys which are a type of alloy body
• Co-Ta-Zr and cobalt (Co)-based amorphous alloys examples include Co-Ta-Zr and cobalt (Co)-based amorphous alloys.
• Ni- based alloys which are a type of alloy body, include Ni-Cr alloys.
• binders include a thermoplastic component such as an acrylic resin and a thermosetting component such as an epoxy resin composition.
• acrylic resins include a carboxyl group-containing acrylic ester copolymer.
• epoxy resin compositions include an epoxy resin (such as a cresol novolak type epoxy resin) as a main agent, a curing agent for the epoxy resin (such as a phenol resin), and a curing accelerator for the epoxy resin (such as an imidazole compound).
• thermoplastic component and the thermosetting component can be used alone or in combination, and preferably, the thermoplastic component and the thermosetting component are used together.
• a thickness of the first magnetic layer 11 is not particularly limited, but is, for example, 100 ⁇ m or more, preferably 200 ⁇ m or more, and is, for example, 2000 ⁇ m or less, preferably 1500 ⁇ m or less, and more preferably 1000 ⁇ m or less.
• the thickness of the first magnetic layer 11 is a distance between the highest point on one surface in the Z-direction (upper part of FIG. 2 ) and the lowest point on the opposite surface in the Z-direction (lower part of FIG. 2 ) of the first magnetic layer 11.
• regions immediately above and below the respective interconnects 20 are preferably raised according to the outer peripheral shape of the interconnects 20. More specifically, the region immediately above the interconnects 20 in the first magnetic layer 11 is preferably located to the upper part compared with the region between the interconnects 20. In the first magnetic layer 11, the region immediately below the interconnects 20 is preferably located to the lower part compared with the region between the interconnects 20.
• the first magnetic layer 11 can be formed along the magnetic field generated around each of the interconnects 20. Therefore, the inductance value can be increased more effectively.
• a form of the first magnetic layer 11 is not limited to this.
• the second magnetic layer 12 has a predetermined thickness and has a sheet-like form extending in the in-plane direction.
• An insulating film 40 is disposed on the front surface 121 of the second magnetic layer 12.
• the second magnetic layer 12 also includes magnetic particles and a binder.
• the third magnetic layer 13 has a predetermined thickness and has a sheet-like form extending in the in-plane direction. Like the first magnetic layer 11 and the second magnetic layer 12, the third magnetic layer 13 also includes magnetic particles and a binder. Examples of the magnetic particles of the second magnetic layer 12 and the third magnetic layer 13 include magnetic particles similar to the magnetic particles exemplified in the first magnetic layer 11. Examples of the binders of the second magnetic layer 12 and the third magnetic layer 13 include a binder similar to the binder exemplified in the first magnetic layer 11.
• the second magnetic layer 12 preferably has a higher relative permeability than the first magnetic layer 11 by appropriately changing a type, shape, and the like of the magnetic particles.
• the inductance value of the inductor member 1 can be increased.
• the third magnetic layer 13 preferably has a higher relative permeability than the first magnetic layer 11 by appropriately changing the type, shape, and the like of the magnetic particles. Thus, the inductance value of the inductor member 1 can be increased.
• the magnetic particles of the first magnetic layer 11 have an isotropic shape such as a roughly spherical shape
• the magnetic particles of the second magnetic layer 12 and the third magnetic layer 13 preferably have an anisotropic shape such as a roughly flat shape.
• the plurality of interconnects 20 are arranged inside the magnetic laminate 10. As shown in FIG. 1 , the plurality of interconnects 20 are spaced apart at different positions in the X-direction. In the embodiment of FIG. 1 , the mutually different positions include the case where the interconnects are arranged at a distance in the X-direction.
• the direction in which the plurality of interconnects 20 are arranged is not limited to the X-direction.
• the direction in which the plurality of interconnects 20 are arranged may hereinafter be referred to as the "first direction". In the first embodiment, the X-direction corresponds to the first direction.
• Each of the plurality of interconnects 20 extends along the Y-direction.
• Each of the plurality of interconnects 20 has, for example, an inductance value corresponding to the length of the interconnect 20.
• the spacing between the adjacent interconnects 20 may be uniform or non-uniform.
• Each of the interconnects 20 is electrically connected to a corresponding terminal pair 30.
• the interconnects 20 are electrically connected to both of the first terminal part 31 and the second terminal part 32 included in the terminal pair 30.
• the interconnect 20 corresponds to a current path through which a current is input from either the first terminal part 31 or the second terminal part 32 in the terminal pair 30 and output from the other.
• the interconnect 20 has a conducting core 21 and an insulating film 22 covering the peripheral surface of the conducting core 21.
• the cross-sectional shape of the conducting core 21 is circular, other shapes such as elliptical shapes and polygonal shapes may be used.
• Examples of materials of the conducting core 21 include metal conductors such as copper, silver, gold, aluminum, nickel, and alloys thereof. Preferably, copper is used.
• the conducting core 21 may have a single-layer structure or a multi-layer structure in which the surface of the core conductor (e.g., copper) is plated (e.g., nickel).
• the conducting core 21 of the first embodiment is copper, but is not limited thereto.
• the radius of the conducting core 21 is, for example, 25 ⁇ m or more, preferably 50 ⁇ m or more, and, for example, 2000 ⁇ m or less, preferably 200 ⁇ m or less.
• the insulating film 22 protects the conducting core 21 from chemicals and water, and prevents short circuits between the conducting core 21 and the magnetic laminate 10 (first magnetic layer 11).
• the insulating film 22 covers the entire outer peripheral surface (circumferential surface) of the conducting core 21.
• the insulating film 22 has an approximately annular shape in cross-sectional view concentric with the interconnect 20.
• Examples of materials of the insulating film 22 include insulating resins such as polyvinyl formal, polyester, polyester imide, polyamide (including nylon), polyimide, polyamide imide, and polyurethane. One of these materials may be used alone, or two or more of these materials may be used in combination.
• the insulating film 22 may be composed of a single layer or a plurality of layers.
• a thickness of the insulating film 22 is substantially uniform in the radial direction of the interconnect 20 at any position in the circumferential direction, for example, 1 ⁇ m or more, preferably 3 ⁇ m or more, and for example, 100 ⁇ m or less, preferably 50 ⁇ m or less.
• a ratio of the radius of the conducting core 21 to the thickness of the insulating film 22 is, for example, one or more, preferably five or more, and for example, 500 or less, preferably 100 or less.
• the inductor member 1 has a plurality of terminal pairs 30. As shown in FIG. 1 , each of the plurality of terminal pairs 30 is electrically connected to a different interconnect 20 among the plurality of interconnects 20. The illustrated terminal pairs 30 are connected to each interconnect 20 one by one, but a plurality of terminal pairs 30 may be connected to each interconnect 20.
• Each of the plurality of terminal pairs 30 has a first terminal part 31 and a second terminal part 32.
• the first terminal part 31 of the terminal pairs 30 may function as an input terminal of a current supplied to the interconnect 20.
• the second terminal part 32 of the terminal pair 30 may function as an output terminal of the current supplied to the interconnect 20.
• the first terminal part 31 of the terminal pair 30 may function as an output terminal of the current supplied to the interconnect 20.
• the second terminal part 32 of the terminal pair 30 may function as an input terminal of the current supplied to the interconnect 20.
• the first terminal part 31 of the terminal pair 30 located on one side in the X-direction (left part in FIG. 1 ) and the first terminal part 31 of the terminal pair 30 located on the other side in the X-direction (right part in FIG. 1 ) are arranged at different positions in the X-direction and are adjacent to each other.
• the second terminal part 32 of the terminal pair 30 located on one side in the X-direction and the second terminal part 32 of the terminal pair 30 located on the other side in the X-direction are arranged at different positions in the X-direction and are adjacent to each other.
• an arrangement of the first terminal part 31 and the second terminal part 32 in the plurality of terminal pairs 30 is not limited thereto.
• first terminal part 31 (second terminal part 32) of the terminal pair 30 located on one side in the X-direction and the second terminal part 32 (first terminal part 31) of the terminal pair 30 located on the other side in the X-direction may be adjacent to each other in the X-direction.
• the first terminal part 31 and the second terminal part 32 of the terminal pair 30 are provided from the front surface 10S on one side in the Z-direction or the back surface 10B on the other side in the Z-direction of the magnetic laminate 10 toward the interconnect 20 in the magnetic laminate 10.
• the front surface 10S on one side in the Z-direction or the back surface 10B on the other side in the Z-direction of the magnetic laminate 10 toward the interconnect 20 in the magnetic laminate 10.
• each of the first terminal part 31 and the second terminal part 32 has an insulating first protrusion 312 and a conductive second protrusion 314. Since the second terminal part 32 has the same configuration as the first terminal part 31, description of the second terminal part 32 will be omitted below.
• the outermost part of the first protrusion 312 contacts the first magnetic layer 11 of the magnetic laminate 10. That is, the first protrusion 312 is disposed at the outermost part of the first terminal part 31. Since an insulating portion such as the first protrusion 312 is disposed at the outermost part of the first terminal part 31, a short circuit between the magnetic laminate 10 and the second protrusion 314 can be prevented.
• the first protrusion 312 of the first embodiment is a cylindrical (columnar) insulating portion extending from the front surface 10S of the magnetic laminate 10 toward the interconnect 20. As shown in FIG. 1 , the planar shape of the first protrusion 312 is substantially circular. However, a shape of the first protrusion 312 is not limited thereto.
• the first protrusion 312 may be connected to, for example, the insulating film 40 covering the front surface 10S of the magnetic laminate 10.
• the first protrusion 312 may be made of the same insulating material as the insulating film 40.
• Materials of the first protrusion 312 and the insulating film 40 are not particularly limited, but as an example, a resin such as epoxy may be used.
• the first protrusion 312 may be made of an insulating material different from the insulating film 40.
• the first protrusion 312 is physically connected to the conducting core 21 of the interconnect 20.
• a bottom surface 312B of the first protrusion 312 reaches inside the conducting core 21.
• the bottom surface 312B of the first protrusion 312 crosses the central part (core) of the conducting core 21 or reaches a position deeper than the central part (core) of the conducting core 21.
• the bottom surface 312B of the first protrusion 312 may be flat or may include a tapered part having a width that decreases downward. Further, a maximum width W1 of the first protrusion 312 is greater than a maximum width of the interconnect 20, that is, a diameter W2.
• the second protrusion 314 is a portion for supplying the current input from the circuit to which the inductor member 1 is connected to the interconnect 20 or for outputting the current flowing through the interconnect 20 to the circuit. More specifically, the second protrusion 314 is a conductive rod-shaped portion disposed inside the first protrusion 312 and penetrating the first protrusion 312. Examples of materials of the second protrusion 314 include metal conductors such as copper, silver, gold, aluminum, nickel, tin, indium, bismuth, and alloys thereof, but are not limited thereto. The second protrusion 314 preferably extends along the Z-direction.
• FIGS. 4A to 10 A method for manufacturing the inductor member 1 according to the first embodiment will be described with reference to FIGS. 4A to 10 .
• the method for manufacturing the inductor member according to the first embodiment includes a process of manufacturing a magnetic structure, a process of forming a first hole in the magnetic structure, a process of forming an insulating first protrusion inside the first hole, a process of forming a second hole penetrating the insulating first protrusion, and a process of forming a conductive second protrusion in the second hole.
• a process of manufacturing a magnetic structure includes a process of manufacturing a magnetic structure, a process of forming a first hole in the magnetic structure, a process of forming an insulating first protrusion inside the first hole, a process of forming a second hole penetrating the insulating first protrusion, and a process of forming a conductive second protrusion in the second hole.
• FIG. 4A is a plan view of the magnetic structure 2.
• FIG. 4B is a C-C cross-sectional view of FIG. 4A .
• the magnetic structure 2 includes a magnetic laminate 10 (magnetic layer) and interconnect 20. Note that, the process of manufacturing the magnetic structure 2 may be referred to as a "first process".
• FIG. 5A is a plan view of the magnetic structure 2 in which the first hole 311 is formed.
• FIG. 5B is a D-D cross-sectional view of FIG. 5A .
• the process of forming the first hole 311 may be referred to as a "second process".
• the second process is performed following the first process.
• the first hole 311 recessed from the surface of the magnetic structure 2, that is, the front surface 10S of the magnetic laminate 10 toward the interconnect 20 is formed.
• the bottom surface 311B of the first hole 311 reaches the conducting core 21 of the interconnect 20 embedded in the magnetic laminate 10. Although not particularly limited, it is preferable that the bottom surface 311B of the first hole 311 crosses the central part (core) of the conducting core 21 or reaches a position deeper than the central part (core) of the conducting core 21.
• the width 311W of the first hole 311 is larger than the maximum width of the interconnect 20, that is, the diameter W2. Thus, the entire width of the interconnect 20 can be exposed.
• first holes 311 are formed per interconnect 20; for example, each of the two interconnects 20 includes two first holes 311. Therefore, the number of the first holes 311 shown in FIG. 5A is four. However, a number of the first holes 311 is not limited to this.
• each interconnect 20 two of the first holes 311 are formed: one for the first terminal part 31 and the other for the second terminal part 32. Moreover, among the first holes 311 formed in different interconnects 20, two of the first holes 311 located in the upper part of FIG. 5A are adjacent in the X-direction. Similarly, among the first holes 311 formed in different interconnects 20, two of the first holes 311 located on the lower part of FIG. 5A are adjacent in the X-direction. However, a positional relationship of each of the first holes 311 is not limited thereto.
• the first hole 311 is preferably formed with a cutting tool such as a router end mill or a drill.
• a method using a router end mill may be referred to as a "routing method”.
• a method using a drill may be referred to as a “drilling method”.
• a "router end mill” is, for example, a cutting tool attached to a machine tool such as a router machine for cutting a printed circuit board or film material.
• the router end mill has a long rod-shaped cutting part along a rotation axis and a blade formed on a lateral face of the cutting part.
• the routing method or the drilling method is a method using a cutting tool having a rod-shaped (approximately cylindrical) cutting part such as a router end mill or a drill.
• the router end mill or the drill is lowered along the Z-direction from the front surface 10S of the magnetic laminate 10, for example, to form a first hole 311 extending approximately perpendicular to the front surface 10S in the magnetic laminate 10.
• the first hole 311 has a columnar form in which the lateral surface 311S of the first hole 311 extends along the Z-direction. Therefore, the first hole 311 has a substantially constant width regardless of the position in the Z-direction (vertical depth direction). That is, in cross-sectional view, the opposing lateral surfaces of the first hole 311 can be made parallel to each other.
• a deep hole with a high aspect ratio (hole depth/hole maximum width) can be compactly formed compared to a hole machining method in which the width of one side in the Z-direction is larger than the width of the other side in the Z-direction, such as an abrasive blasting method in which a hole is formed by colliding abrasive particles or a laser drilling method in which a hole is formed by irradiating a laser beam.
• the bottom surface 311B of the first hole 311 has a flat shape.
• the bottom surface 311B of the first hole 311 includes a tapered part having a width that decreases downward.
• FIG. 6A is a plan view of the magnetic structure 2 in which the first protrusion 312 is formed.
• FIG. 6B is an E-E cross-sectional view of FIG. 6A .
• the process of forming the first protrusion 312 may be referred to as a "third process".
• the third process is performed following the second process.
• an insulating film is filled inside each of the first holes 311 to form the first protrusion 312.
• an insulating film including the region of the first protrusion 312 is laminated on the front surface 10S of the magnetic laminate 10.
• the laminated insulating film may include the region of the insulating film 40 connected to the first protrusion 312 in addition to the first protrusion 312.
• the method of forming the first protrusion 312 is not limited thereto.
• the opposing lateral surfaces of the first protrusions 312 may be parallel in cross-sectional view. Since the first hole 311 is a deep hole with a high aspect ratio, the first protrusion 312 with a high aspect ratio can be compactly formed.
• FIG. 7A is a plan view of the magnetic structure 2 in which the second hole 313 is formed.
• FIG. 7B is an F-F cross-sectional view of FIG. 7A .
• the process of forming the second hole 313 may be referred to as the "fourth process”.
• the fourth process is performed following the third process.
• the second hole 313 is formed from a surface 3121 where the one side in the Z-direction of each of the first protrusions 312 is located toward the other side in the Z-direction.
• the second hole 313 is formed using such as a routing method, a drilling method, an abrasive blasting method, and a laser drilling method. Among them, it is preferable to use the routing method and the drilling method.
• a rod-shaped (approximately cylindrical) cutting tool such as a router end mill or a drill can be lowered from the front surface 10S of the magnetic laminate 10 in the Z-direction, for example, to form a deep hole with a high aspect ratio in the first protrusion 312.
• the opposing lateral surfaces of the second hole 313 can be made parallel to each other in cross-sectional view.
• the lateral surfaces 313S of the second hole 313 can be formed substantially parallel to the lateral surfaces 312S of the first protrusion 312.
• the second hole 313 can be prevented from being formed outside the first protrusion 312 by piercing the lateral surfaces 312S of the first protrusion 312.
• the tapered part 313T having the same shape as the tip of the drill can be formed on the bottom surface 313B of the second hole 313. While the conductive second protrusion 314 is formed in the second hole 313, the tapered part 314T is formed on the bottom surface 314B of the second protrusion 314 following the tapered part 313T of the second hole 313 (see FIG. 9B ). As a result, a contact area between the second protrusion 314 and the conducting core 21 of the interconnect 20 is increased, and resistance generated at both interfaces can be reduced.
• the bottom surface 313B is, for example, flat (see FIG. 8 ).
• a deep hole with a high aspect ratio (hole depth/hole maximum width) can be formed compactly compared with hole machining methods in which the width of one side in the Z-direction is larger than the width of the other side in the Z-direction, such as the abrasive blasting method in which a hole is formed by colliding abrasive particles and the laser drilling method in which a hole is formed by irradiating a laser beam.
• the second hole 313 penetrates the first protrusion 312 in the thickness direction. That is, the bottom surface 313B of the second hole 313 reaches the conducting core 21 of the interconnect 20 and is deeper than the bottom surface 312B of the first protrusion 312. The second hole 313 is physically connected to the conducting core 21 of the interconnect 20.
• the width 311W of the first hole 311 is larger than the maximum width W2 of the interconnect 20 (see FIG. 5B ). Accordingly, the width 312W of the first protrusion 312 is larger than the maximum width W2 of the interconnect 20. Therefore, the bottom surface 313B of the second hole 313 can be securely connected to the conducting core 21 of the interconnect 20 by forming the second hole 313 substantially vertically with the position of the first protrusion 312 as a guide.
• FIG. 9A is a plan view of the magnetic structure 2 in which the second protrusion 314 is formed.
• FIG. 9B is a G-G cross-sectional view of FIG. 9A . Note that, the process of forming the second protrusion 314 may be referred to as a "fifth process".
• the fifth process is performed after the fourth process.
• the second hole 313 is filled with an electric conductor.
• the conductive second protrusion 314 is formed in the second hole 313.
• the method of filling the electric conductor included in the second protrusion 314 is not particularly limited, but examples include electroplating, electroless plating, or applying sintered or thermosetting conductive paste.
• sintered conductive paste is preferable from the viewpoint of reducing electric resistance.
• the bottom surface 314B of the second protrusion 314 reaches inside the conducting core 21 of the interconnect 20. That is, the second protrusion 314 is electrically connected to the interconnect 20.
• the bottom surface 314B of the second protrusion 314 is deeper than the bottom surface 312B of the first protrusion 312.
• the bottom surface 314B of the second protrusion 314 includes a tapered part 314T having a width that decreases downward.
• the contact area between the second protrusion 314 and the conducting core 21 of the interconnect 20 can be increased.
• the resistance generated at the contact area between the second protrusion 314 and the conducting core 21 can be reduced.
• the opposing lateral surfaces of the second protrusions 314 may be parallel in cross-sectional view.
• the second hole 313 is a deep hole with a high aspect ratio
• the second protrusion 314 also becomes a protrusion with a high aspect ratio.
• the bottom surface 314B of the second protrusion 314 is formed flat, as shown in FIGS. 8 and 10 .
• the inductor member 1 can be manufactured through the first to fifth processes.
• the insulating film is filled into the first hole 311 to form the insulating first protrusion 312 that extends approximately perpendicular to the front surface 10S of the magnetic laminate 10 and has a high aspect ratio.
• the second hole 313 is formed inside the first protrusion 312 penetrating in the Z-direction (thickness direction), and the conductive film is filled into the second hole 313 to form the conductive second protrusion 314 that has a high aspect ratio similar to the first protrusion 312.
• each interconnect 20 to be properly connected to the corresponding second protrusion 314, even when, for example, the spacing between a plurality of interconnects 20 adjacent in the X-direction decreases due to miniaturization of the inductor member 1. That is, machining accuracy can be improved such that each of the interconnects 20 is electrically and physically connected to the corresponding terminal part (first terminal part 31, second terminal part 32), even when the spacing between the plurality of interconnects 20 adjacent in the X-direction decreases.
• the second protrusions 314 can be insulated from each other even if the distance between the second protrusions 314 connected to respective interconnects 20 becomes closer. As a result, a short circuit can be prevented between the adjacent second protrusions 314, and the yield of the inductor member 1 can be controlled against decreasing.
• the second hole 313 and the second protrusion 314 penetrating the inside of the first protrusion 312 are formed. Therefore, the bottom surface 314B of the second protrusion 314 can be surely connected to the conducting core 21 of the interconnect 20. Thus, the conducting core 21 and the second protrusion 314 can be properly electrically connected.
• FIGS. 11 to 15 A method for manufacturing an inductor member according to a second embodiment will be described with reference to FIGS. 11 to 15 .
• FIG. 11 is a plan view of the inductor member 1A.
• the inductor member 1A has a magnetic laminate 10, a plurality of interconnects 20, a terminal pair 30A having a first terminal part 31A and a second terminal part 32A, and an insulating film 40.
• the structures of the first terminal part 31A and the second terminal part 32A are different from those of the first terminal part 31 and the second terminal part 32 of the inductor member 1 manufactured with the inductor member manufacturing method according to the first embodiment. Since the structure of the second terminal part 32A is the same as that of the first terminal part 31A, the description of the second terminal part 32A is omitted.
• the first terminal part 31A has an insulating first protrusion 312A and a conductive second protrusion 314A. As shown in FIG. 11 , the first protrusion 312A has a long planar shape in the Y-direction. That is, the longitudinal direction of the first protrusion 312A is along the longitudinal direction of the interconnect 20.
• a plurality of second protrusions 314A are formed inside the first protrusion 312A. All of the plurality of second protrusions 314A are connected to the conducting core 21 of the interconnect 20. The number of the second protrusions 314A shown in FIG. 11 is five, but is not limited thereto.
• the method for manufacturing the inductor member according to the second embodiment includes a process of manufacturing a magnetic structure (first process), a process of forming a first hole in the magnetic structure (second process), a process of forming an insulating first protrusion inside the first hole (third process), a process of forming a second hole penetrating the insulating first protrusion (fourth process), and a process of forming a conductive second protrusion in the second hole (fifth process) .
• the first, third, and fifth processes are the same as those of the first embodiment. Conversely, the second and fourth processes are different from those of the first embodiment.
• FIG. 12A is a plan view of the magnetic structure 2 in which the first hole 311A is formed.
• FIG. 12B is a cross-sectional view along the H-H cut line in FIG. 12A .
• FIG. 13 is an I-I cross-sectional view of FIG. 12A for describing the method of forming the first hole 311A.
• a first hole 311A having a predetermined depth in the Z-direction is formed on the front surface 10S of the magnetic laminate 10 with the router processing method.
• the width W3 of the first hole 311A is larger than the diameter W2 of the interconnect 20.
• the first hole 311A extends in the Y-direction as shown in FIG. 12A .
• the router end mill 60 is lowered from the front surface 10S of the magnetic laminate 10 to the other side in the Z-direction (lower part in the figure).
• a hole extending in the Z-direction corresponding to one end of the first hole 311A is formed in the magnetic laminate 10.
• the router end mill 60 is moved to one side in the Y-direction (right part in the figure) while being inserted into the hole.
• the first hole 311A extending in the Y-direction is formed in the magnetic laminate 10.
• FIG. 14A is a plan view of the magnetic structure 2 in which the second hole 313A is formed.
• FIG. 14B is a J-J cross-sectional view of FIG. 14A .
• the first hole 311A is filled with an insulating film.
• an insulating first protrusion 312A (see FIG. 11 ) is formed in the first hole 311A.
• a plurality of second holes 313A are formed in the fourth process.
• each of the plurality of second holes 313A is not particularly limited, but it is preferable to use a drilling method in which a deep hole having a high aspect ratio can be formed inside the first protrusion 312A along the Z-direction and a tapered part 313AT can be formed at the tip.
• the second hole 313A may be formed using a router method.
• the planar shape of the second hole 313A may be a shape extending in the Y-direction as shown in FIG. 15 .
• the lateral surface 313AS of the second hole 313A is preferably parallel to the lateral surface 312AS of the first protrusion 312A as shown in FIG. 14B . Further, both lateral surfaces 313AS of the second hole 313A are preferably parallel.
• the bottom surface 313AB of the second hole 313A is deeper than the bottom surface 312AB of the first protrusion 312A.
• each of the plurality of second holes 313A is filled with a conductive film.
• the second protrusion 314A (see FIG. 11 ) is formed.
• the contact area of the interconnect 20 with the conducting core 21 can be increased.
• the amount of current supplied from the second protrusion 314A to the conducting core 21 can be increased.

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