JP7352363B2 - Magnetic wiring circuit board and its manufacturing method - Google Patents

Description

The present invention relates to a magnetic wiring circuit board and a method for manufacturing the same.

2. Description of the Related Art Magnetic sheets such as inductors that include an air-core coil and a magnetic layer embedding the air-core coil are conventionally known.

For example, a magnetic sheet has been proposed that includes an air-core coil, an anisotropic composite magnetic part filled inside the air-core coil, and an anisotropic composite magnetic sheet laminated on the top surface of the air-core coil ( For example, see Patent Document 1).

In the method for manufacturing a magnetic sheet disclosed in Patent Document 1, first, an air-core coil is prepared, then an anisotropic composite magnetic part is filled inside the center core of the air-core coil, and then an anisotropic composite magnetic sheet is prepared. are laminated on top of the air-core coil.

In the inductor of Patent Document 1, the magnetic permeability inside the air-core coil is increased by the anisotropic composite magnetic portion, and therefore, the inductance is excellent.

Japanese Patent Application Publication No. 2009-9985

However, in the method described in Patent Document 1, the anisotropic composite magnetic portion and the anisotropic composite magnetic sheet are formed in separate steps on the magnetic sheet. Therefore, there is a problem that the number of manufacturing steps is large, and as a result, the magnetic sheet cannot be easily manufactured.

Further, the magnetic sheet is required to have even better inductance.

The present invention provides a method for manufacturing a magnetic wired circuit board in which a magnetic layer can be easily formed at one time, and a magnetic wired circuit board having high inductance .

The present invention (1) provides two press plates, an insulating layer, a plurality of wiring portions arranged at intervals from each other in a predetermined direction on one side in the thickness direction of the insulating layer, and a first magnetic sheet. a sandwiching step of sandwiching the release cushion sheet in that order; and a step of hot pressing the insulating layer, the plurality of wiring parts, the first magnetic sheet, and the release cushion sheet using the press plate. In the first pressing step, a first magnetic sheet is applied from the first magnetic sheet so as to fill between the plurality of wiring portions and to cover one surface of the wiring portion in the thickness direction. The release cushion sheet includes a first layer and a second layer disposed on one side of the first layer in the thickness direction, and the tensile storage modulus of the second layer at 110°C. The present invention includes a method for manufacturing a magnetic wired circuit board in which E' is lower than the tensile storage modulus E' of the first layer at 110°C.

According to this method for manufacturing a magnetic wired circuit board, the magnetic layer is formed in the first pressing step of hot pressing the insulating layer, the plurality of wiring parts, the first magnetic sheet, and the release cushion sheet using a press plate. It can be easily formed all at once.

Moreover, since the tensile storage modulus E' of the second layer in the release cushion sheet at 110°C is lower than the tensile storage modulus E' of the first layer at 110°C, the first pressing step is performed at the above temperature. When carrying out the process, the second layer becomes more flexible than the first layer, so the second layer flows more easily than the first layer, and the first magnetic sheet is connected to a plurality of wires via the first layer. It can be extruded between parts. Therefore, in the first pressing step, it is possible to reliably form a magnetic layer that fills between the plurality of wiring parts and covers the facing surfaces of the wiring parts.

As a result, a magnetic wiring circuit board having high inductance can be obtained.

The present invention (2) includes the method for manufacturing a magnetic wiring circuit board according to (1), wherein the second layer has a tensile storage modulus E' at 110° C. of 20 MPa or less.

In this method for manufacturing a magnetic printed circuit board, the tensile storage modulus E' of the second layer at 110° C. is as low as 20 MPa or less. can flow reliably. Therefore, the second layer can push the first magnetic sheet between the plurality of wiring sections. As a result, the spaces between the plurality of wiring sections can be reliably filled with the magnetic layer, and a magnetic wiring circuit board having high inductance can be obtained.

The present invention (3) provides the method for manufacturing a magnetic wired circuit board according to (1) or (2), wherein the ratio of the thickness T2 of the second layer to the thickness T1 of the wiring portion is 0.5 or more. including.

In this method for manufacturing a magnetic wired circuit board, the ratio of the thickness T2 of the second layer to the thickness T1 of the wiring portion is as high as 0.5 or more, so in the first pressing step, the thickness of the wiring portion is The first magnetic sheet on one side in the thickness direction can be flexibly hot-pressed, so that a sufficient thickness of the magnetic layer corresponding to this portion can be ensured. As a result, one side of the wiring portion in the thickness direction can be reliably covered with the magnetic layer.

In the present invention (4), the release cushion sheet further includes a third layer disposed on one side of the second layer in the thickness direction, and the second layer has a tensile storage modulus E' at 110°C. , the method for manufacturing a magnetic wiring circuit board according to any one of (1) to (3), wherein the tensile storage modulus E' at 110° C. of the third layer is lower than that of the third layer.

In this method for manufacturing a magnetic printed circuit board, the release cushion sheet further includes a third layer having a tensile storage modulus E' higher than the tensile storage modulus E' at 110° C. of the second layer. When performing the first pressing step, the third layer, which is harder than the second layer, can suppress deformation of the release cushion sheet to one side in the thickness direction. Therefore, the first pressing step can be performed reliably.

The present invention (5) provides the magnetic material according to any one of (1) to (4), wherein the ratio of the thickness T3 of the first magnetic layer to the thickness T1 of the wiring portion is 0.5 or more. Includes a method for manufacturing a printed circuit board.

In this method for manufacturing a magnetic wired circuit board, since the ratio of the thickness T3 of the first magnetic layer to the thickness T1 of the wiring portion is as high as 0.5 or more, the magnetic layer is reliably filled between the plurality of wiring portions. can be formed. As a result, the effective magnetic permeability between the wiring parts can be improved, and a magnetic wiring circuit board having high inductance can be obtained.

In the present invention (6), the press plate includes the insulating layer, the plurality of wiring parts, the first magnetic layer formed in the first step, the second magnetic sheet, and the release cushion sheet. further comprising a second pressing step of hot pressing, in the second pressing step, a second magnetic layer is formed from the second magnetic sheet, thereby forming a magnetic layer comprising the first magnetic layer and the second magnetic layer. The method includes the method for manufacturing a magnetic wiring circuit board according to any one of (1) to (4), in which a layer is formed.

Since this method for manufacturing a magnetic wiring circuit board further includes a second pressing step, a thick magnetic layer can be formed. Therefore, the effective magnetic permeability between the wiring parts can be improved, and a magnetic wiring circuit board having high inductance can be obtained.

In the present invention (7), the ratio of the thickness T3 of the first magnetic layer to the thickness T1 of the wiring portion is less than 0.5, and the ratio of the thickness T3 of the first magnetic layer and the thickness of the second magnetic layer is less than 0.5. The method of manufacturing a magnetic wired circuit board according to (6), wherein the ratio of the total thickness T4 to the thickness T1 of the wiring portion is 0.5 or more.

If the ratio of the thickness T3 of the first magnetic layer to the thickness T1 of the wiring part is low, such as less than 0.5, the magnetic layer becomes thin, making it difficult to fill the spaces between the plurality of wiring parts with the magnetic layer. easy.

However, according to this method of manufacturing a magnetic wired circuit board, the ratio of the sum of the thickness T3 of the first magnetic layer and the thickness T4 of the second magnetic layer to the thickness T1 of the wiring portion is as high as 0.5 or more. The magnetic layer including the first magnetic layer and the second magnetic layer is thick, so that the thick magnetic layer can reliably fill the space between the plurality of wiring sections. As a result, a magnetic wiring circuit board having high inductance can be obtained.

In the present invention (8), the first magnetic sheet and the second magnetic sheet contain magnetic particles, and the content ratio of the magnetic particles in the first magnetic sheet is the content ratio of the magnetic particles in the second magnetic sheet. The manufacturing method of a magnetic wired circuit board according to (6) or (7) is included.

According to this method for manufacturing a magnetic wiring circuit board, the content ratio of magnetic particles in the first magnetic sheet is lower than the content ratio of magnetic particles in the second magnetic sheet. Therefore, even if the first magnetic sheet, which is more flexible than the second magnetic sheet, is reliably arranged between the plurality of wiring parts, and the second magnetic sheet is more rigid than the first magnetic sheet, By disposing it in the first magnetic layer already arranged between the plurality of wiring parts, the spaces between the plurality of wiring parts can be filled with the magnetic layer including the first magnetic layer and the second magnetic layer. .

Furthermore, the inductance of the magnetic wiring circuit board can be improved by the second magnetic layer formed from the second magnetic sheet containing magnetic particles at a higher content rate than the content rate of magnetic particles in the first magnetic sheet. .

The present invention (9) includes an insulating layer, a plurality of wiring portions arranged at intervals from each other in a predetermined direction on one side in the thickness direction of the insulating layer, and filling between the plurality of wiring portions, and a magnetic layer covering an opposing surface disposed opposite to the one surface in the thickness direction of the wiring portion, the magnetic layer being disposed on the opposing surface of the plurality of wiring portions; a plurality of convex portions that protrude toward one side; and a concave portion located between the plurality of convex portions and recessed toward the other side in the thickness direction with respect to the adjacent convex portions; has only one apex located on the most one side in the thickness direction, and the recess has a substantially curved shape that sinks toward the other side in the thickness direction, and the concave portion has a substantially curved shape that sinks toward the other side in the thickness direction. The magnetic wiring circuit board includes a bottom portion located on one side in the thickness direction with respect to a virtual plane passing through the opposing surface.

In this magnetic wiring circuit board, the convex portion has only one apex, the concave portion has a substantially curved shape concave toward the other side in the thickness direction, and the opposing surfaces of the adjacent wiring portions are It has a bottom portion located on one side in the thickness direction with respect to the virtual plane through which it passes. Therefore, the magnetic permeability around the wiring portion can be improved by the magnetic path that smoothly passes through the above-described convex portions and concave portions.

As a result, this magnetic wiring circuit board has high inductance .

According to the method for manufacturing a magnetic wiring circuit board of the present invention, a magnetic layer can be easily formed at one time, and a magnetic wiring circuit board having high inductance can be obtained.

The magnetic wired circuit board of the present invention has high inductance because the magnetic path passing smoothly through the convex portions and concave portions can improve the magnetic permeability around the wiring portion.

1A to 1C are manufacturing process diagrams of a first embodiment of the method for manufacturing a magnetic wiring circuit board of the present invention, in which FIG. 1A is a sandwiching process, FIG. 1B is a first pressing process, and FIG. 1C is a magnetic wiring circuit board manufacturing method. The process of obtaining a wired circuit board is shown. 2A to 2B are process diagrams detailing the first pressing step shown in FIG. 1B, and FIG. 2A is a state in which the first magnetic sheet contacts the wiring part at the start of hot pressing. , FIG. 2B shows a mode in which, following FIG. 2A, the hot press progresses and the first magnetic sheet is pressed against the deforming release cushion sheet and fills the space between them along the wiring portion. FIG. 3 is a cross-sectional view of the magnetic wiring circuit board obtained in FIGS. 1A to 1C, showing a cross-sectional view depicting magnetic particles in the magnetic layer. 4A to 4B are manufacturing process diagrams of a second embodiment of the method for manufacturing a magnetic wired circuit board of the present invention, with FIG. 4A showing the sandwiching step and FIG. 4B showing the first pressing step. 5C to 5E are manufacturing process diagrams of the second embodiment of the method for manufacturing a magnetic wiring circuit board of the present invention following FIG. 4B, and FIG. 5C shows the step of further arranging the second magnetic sheet, and FIG. 5D However, the second pressing step, FIG. 5E, shows the step of obtaining a magnetic wiring circuit board. 6A to 6C are manufacturing process diagrams of a modified example, in which FIG. 6A shows the sandwiching step, FIG. 6B shows the first pressing step, and FIG. 6C shows the step of obtaining a magnetic wiring circuit board. FIG. 7 is a cross-sectional view of the magnetic wired circuit board shown in FIG. 6C, in which the hatching of the wiring portion is removed and the magnetic particles are made clear. FIG. 8 shows an image processing diagram of the SEM photograph of Example 1. FIG. 9 shows an image processing diagram of the SEM photograph of Example 2. FIG. 10 shows an image processing diagram of the SEM photograph of Example 3. FIG. 11 shows an image processing diagram of the SEM photograph of Example 4. FIG. 12 shows an image processing diagram of the SEM photograph of Comparative Example 1. FIG. 13 shows an image processing diagram of the SEM photograph of Comparative Example 2. FIG. 14 shows an image processing diagram of the SEM photograph of Comparative Example 3. FIG. 15 shows an image processing diagram of the SEM photograph of Comparative Example 4.

<First embodiment>
A first embodiment of a magnetic wiring circuit board and a method for manufacturing the same according to the present invention will be described with reference to FIGS. 1A to 2B.

Note that in FIGS. 2A and 2B, hatching of the second layer 32 (described later) is omitted in order to clearly indicate the flow pressure that causes deformation with arrows.

As shown in FIGS. 1A to 2B, the method for manufacturing the magnetic wired circuit board 1 includes two press plates 20, an insulating layer 2, a plurality of wiring parts 4, a first magnetic sheet 5, and a release cushion sheet. 6 in that order (see FIG. 1A), and heat the insulating layer 2, the plurality of wiring parts 4, the first magnetic sheet 5, and the release cushion sheet 6 using the two press plates 20. A first pressing step (see FIG. 1B) is provided. In the method for manufacturing the magnetic wiring circuit board 1, the above-described steps are performed in order.

As shown in FIG. 1A, in the sandwiching step, first, an insulating layer 2, a plurality of wiring sections 4, a first magnetic sheet 5, and a release cushion sheet 6 are prepared.

The insulating layer 2 has a sheet shape extending in a direction perpendicular to the thickness direction (planar direction), and has a first insulating surface 3 as one surface in the thickness direction and a second insulating surface 9 as the other surface. The insulating layer 2 is a support material that supports a plurality of wiring sections 4, which will be described next, and is also a support layer that supports the magnetic wiring circuit board 1. Further, the insulating layer 2 has toughness. Examples of the material for the insulating layer 2 include insulating materials such as polyimide resin, polyester resin, and acrylic resin. Moreover, the insulating layer 2 may be either a single layer or a multilayer. When the insulating layer 2 is multilayer, as shown by the imaginary line, a first support layer 12 made of, for example, polyester resin (polyethylene terephthalate, etc.), a pressure-sensitive adhesive layer 13 made of, for example, acrylic resin, For example, the second support layer 14 made of polyimide resin is provided in order toward one side in the thickness direction. In this case, the second support layer 14 is pressure-sensitively bonded (supported) to the support layer 12 via the pressure-sensitive adhesive layer 13 . The second support layer 14 forms the first insulating surface 3 . Support layer 12 forms second insulating surface 9 .

The plurality of wiring parts 4 are spaced apart from each other in the plane direction (an example of a predetermined direction) (specifically, a first direction corresponding to the left-right direction in FIG. 1A) on the first insulating surface 3 of the insulating layer 2. It is located. The shape of the plurality of wiring portions 4 in plan view (when viewed in the thickness direction) is not particularly limited, and includes, for example, a substantially coil shape, a substantially loop shape, a substantially S shape, and the like.

The cross-sectional shape of each of the plurality of wiring parts 4 (specifically, the cross-sectional view when cut along the thickness direction and the first direction) is not particularly limited, and may be, for example, approximately rectangular, approximately trapezoidal, etc. At least a quadrilateral shape in which a pair of faces facing each other in the thickness direction are parallel to each other can be mentioned.

Further, the plurality of wiring portions 4 are arranged on the first insulating surface 3 of the insulating layer 2. Preferably, when the insulating layer 2 includes the support layer 12, the pressure-sensitive adhesive layer 13, and the second support layer 14, the plurality of wiring parts 4 are connected to the insulating layer 2 by contacting the second support layer 14. Supported.

Each of the plurality of wiring portions 4 is in contact with an opposing surface 15 that is arranged to face the first insulating surface 3 of the insulating layer 2 at a distance on one side in the thickness direction, and the first insulating surface 3 of the insulating layer 2. The support surface 16 integrally includes a supported surface 16 and side surfaces 17 that connect the peripheral edges of the opposing surface 15 and the supported surface 16 (specifically, both side surfaces that connect both edges in the first direction).

The opposing surface 15 is a flat surface along the first direction.

The supported surface 16 is a flat surface parallel to the opposing surface 15.

The side surface 17 extends along the thickness direction. One wiring section 4 is provided with two side surfaces 17 . The two side surfaces 17 are arranged opposite to each other at a distance in the first direction. If the wiring portion 4 has a substantially trapezoidal shape, the two side surfaces 17 have a shape that is inclined toward each other as they advance toward one side in the thickness direction. That is, the side surface 17 is a tapered surface whose facing length becomes shorter toward one side in the thickness direction.

Examples of the material of the plurality of wiring parts 4 include metals (conductors) such as copper.

The dimensions of the plurality of wiring parts 4 are appropriately set according to the use and purpose of the magnetic wiring circuit board 1, and for example, the thickness T1 (the length of the facing surface 15 and the supported surface 16) is 20 μm or more, for example, Preferably, it is 50 μm or more, and for example, 300 μm or less, preferably 150 μm or less. The width of the wiring portion 4 is, for example, the length of the opposing surface 15 in the first direction of 1900 μm or less and 20 μm or more, and the length of the supported surface 16 in the first direction is, for example, 2000 μm or less and 30 μm or more. The interval between the plurality of wiring parts 4 is, for example, 2100 μm or less and 60 μm or more as the interval in the first direction of the side surface 17 of the adjacent wiring part 4, and the distance of the supported surface 16 of the adjacent wiring part 4 in the first direction. For example, the spacing is 2000 μm or less and 30 μm or more.

The ratio (T1/width) of the thickness T1 of the wiring portion 4 to the width of the wiring portion 4 (the length in the first direction of the opposing surface 15 or the supported surface 16) is, for example, 0.01 or more, preferably 0.01 or more. 025 or more, and for example, 10 or less, preferably 5 or less. The ratio (T1/distance) of the thickness T1 of the wiring portions 4 to the spacing between the wiring portions 4 (the spacing in the first direction of the opposing surface 15 or the supported surface 16) is, for example, 0.01 or more, preferably 0. .025 or more, and for example, 10 or less, preferably 5 or less.

The insulating layer 2 and the plurality of wiring sections 4 are prepared, for example, as a wired circuit board 40 that includes them in advance. Specifically, the wired circuit board 40 includes an insulating layer 2 and a plurality of wiring portions 4 arranged on the first insulating surface 3 of the insulating layer 2. The printed circuit board 40 preferably consists of only the insulating layer 2 and the plurality of wiring parts 4.

The first magnetic sheet 5 has a sheet shape extending in the plane direction. The first magnetic sheet 5 is a magnetic sheet for forming the magnetic layer 21 (see FIG. 1C) in the magnetic wiring circuit board 1. The first magnetic sheet 5 has a first magnetic surface 18 as one surface in the thickness direction and a second magnetic surface 19 as the other surface.

The first magnetic surface 18 is a flat surface along the surface direction.

The second magnetic surface 19 is a flat surface parallel to the first magnetic surface 18, which is disposed to face the first magnetic surface 18 at a distance from the other side in the thickness direction.

Note that the first magnetic sheet 5 is deformed (fluidized) by the hot pressing in the first pressing step and is arranged along the opposing surface 15 and side surface 17 of the plurality of wiring sections 4.

Examples of the material for the first magnetic sheet 5 include a magnetic composition containing magnetic particles 48 and a resin.

Examples of the magnetic material constituting the magnetic particles 48 include soft magnetic materials and hard magnetic materials. Preferably, a soft magnetic material is used from the viewpoint of inductance.

As a soft magnetic material, for example, a single metal body containing one type of metal element in a pure substance state, for example, one or more types of metal element (first metal element) and one or more types of metal element (second metal element), Examples include alloys that are eutectic bodies (mixtures) with metallic elements) and/or nonmetallic elements (carbon, nitrogen, silicon, phosphorus, etc.). These can be used alone or in combination.

As the single metal body, for example, a single metal body consisting of only one type of metal element (first metal element) can be mentioned. The first metal element is appropriately selected from, for example, iron (Fe), cobalt (Co), nickel (Ni), and other metal elements that can be contained as the first metal element in the soft magnetic material. .

Further, as a single metal body, for example, a form that includes a core containing only one type of metal element and a surface layer containing an inorganic substance and/or an organic substance that modifies part or all of the surface of the core, for example, Examples include a form in which an organic metal compound or an inorganic metal compound containing the first metal element is decomposed (thermally decomposed, etc.). More specifically, the latter form is iron powder (sometimes referred to as carbonyl iron powder) obtained by thermally decomposing an organic iron compound containing iron as the first metal element (specifically, carbonyl iron). Examples include. Note that the position of the layer containing an inorganic substance and/or an organic substance that modifies a portion containing only one type of metal element is not limited to the above-mentioned surface. The organometallic compounds and inorganic metal compounds from which a single metal body can be obtained are not particularly limited, and include known or commonly used organometallic compounds and inorganic metal compounds from which a soft magnetic single metal body can be obtained. It can be selected as appropriate.

An alloy is a eutectic mixture of one or more metal elements (first metal element) and one or more metal elements (second metal element) and/or nonmetal elements (carbon, nitrogen, silicon, phosphorus, etc.) It is not particularly limited as long as it can be used as an alloy of soft magnetic materials.

The first metal element is an essential element in the alloy, and examples thereof include iron (Fe), cobalt (Co), and nickel (Ni). Note that if the first metal element is Fe, the alloy body is a Fe-based alloy; if the first metal element is Co, the alloy body is a Co-based alloy; and even if the first metal element is Ni, the alloy body is a Fe-based alloy. For example, the alloy body is a Ni-based alloy.

The second metal element is an element (subcomponent) secondarily contained in the alloy body, and is a metal element that is compatible (eutectic) with the first metal element, such as iron (Fe) (second metal element). (When the first metal element is other than Fe), Cobalt (Co) (When the first metal element is other than Co), Nickel (Ni) (When the first metal 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), yttrium (Y), strontium (Sr), and various rare earth elements. These can be used alone or in combination of two or more.

The nonmetallic element is an element (subcomponent) secondarily contained in the alloy body, and is a nonmetallic element that is compatible (eutectic) with the first metal element, such as boron (B), carbon, etc. (C), nitrogen (N), silicon (Si), phosphorus (P), sulfur (S), and the like. These can be used alone or in combination of two or more.

Examples of Fe-based alloys, which are examples of alloys, include magnetic stainless steel (Fe-Cr-Al-Si alloy) (including electromagnetic stainless steel), Sendust (Fe-Si-Al alloy) (including Super Sendust), and 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 (stainless steel ferrite, Mn-Mg ferrite, Mn-Zn ferrite, Ni-Zn ferrite, Ni-Zn-Cu ferrite, Cu-Zn ferrite, Cu-Mg-Zn ferrite, etc.) (including soft ferrite), permendur (Fe--Co alloy), Fe--Co--V alloy, Fe-based amorphous alloy, etc.

Co-based alloys, which are examples of alloy bodies, include Co--Ta--Zr, cobalt (Co)-based amorphous alloys, and the like.

Examples of the Ni-based alloy, which is an example of the alloy body, include a Ni--Cr alloy.

Among these soft magnetic materials, from the viewpoint of magnetic properties, alloys are preferred, more preferably Fe-based alloys, still more preferably sendust (Fe-Si-Al alloy), and particularly preferred to obtain high magnetic permeability. From this point of view, Sendust with a Si content of 9 to 15% by mass can be mentioned. In addition, the soft magnetic material is preferably a single metal body, more preferably a single metal body containing iron element in a pure state, and even more preferably iron alone or iron powder (carbonyl iron powder). Can be mentioned.

The shape of the magnetic particles 48 is not particularly limited, and examples include a substantially flat shape (plate shape), a substantially spherical shape, a substantially needle shape, and an irregular shape, and preferably a substantially flat shape (plate shape). In addition to the anisotropic magnetic particles 48, the first magnetic sheet 5 can also contain non-anisotropic magnetic particles. The non-anisotropic magnetic particles may have, for example, a spherical, granular, lump, or pellet shape. The average particle diameter of the non-anisotropic magnetic particles is, for example, 0.1 μm or more, preferably 0.5 μm or more, and, for example, 200 μm or less, preferably 150 μm or less.

The average particle diameter (average maximum length) of the anisotropic magnetic particles 48 is, for example, 3.5 μm or more, preferably 10 μm or more, and also, for example, 100 μm or less.

The volume ratio of the magnetic particles 48 in the magnetic composition (first magnetic sheet 5) is, for example, 15 volume% or more, preferably 50 volume% or more, and, for example, 90 volume% or less, preferably 80 volume%. % or less.

Examples of the resin include thermoplastic components and thermosetting components. These can be used alone or in combination, and preferably a thermoplastic component and a thermosetting component are used in combination. If a thermoplastic component and a thermosetting component are used in combination, the magnetic composition can flow sufficiently in the first step to fill the spaces between the plurality of wiring sections 4, and is then completely cured, resulting in excellent durability. A magnetic layer 21 can be formed.

Examples of thermoplastic components include natural rubber, butyl rubber, isoprene rubber, chloroprene rubber, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, polybutadiene resin, polycarbonate resin, Thermoplastic polyimide resin, polyamide resin (6-nylon, 6,6-nylon, etc.), phenoxy resin, acrylic resin, saturated polyester resin (PET, etc.), polyamide-imide resin, fluororesin, styrene-isobutylene-styrene block copolymer Examples include thermoplastic resins such as. These thermoplastic components can be used alone or in combination of two or more.

Preferably, the thermoplastic component is an acrylic resin.

Examples of acrylic resins include carboxyl group-containing (meth)acrylic resins obtained by polymerizing monomer components containing (meth)acrylic acid alkyl esters having linear or branched alkyl groups and other monomers (copolymerizable monomers). ) acrylic ester copolymers (preferably carboxyl group-containing acrylic ester copolymers).

Examples of the alkyl group include alkyl groups having 1 to 6 carbon atoms such as methyl, ethyl, propyl, isopropyl, n-butyl, t-butyl, isobutyl, pentyl, and hexyl.

Examples of other monomers include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid.

The proportion of the thermoplastic component in the resin (solid content proportion) is, for example, 25% by mass or more and 80% by mass or less.

The thermosetting component includes, for example, a base agent, a curing agent, and a curing accelerator.

Examples of the main resin include epoxy resin, phenol resin, melamine resin, vinyl ester resin, cyano ester resin, maleimide resin, and silicone resin. From the viewpoint of heat resistance, etc., the base resin is preferably an epoxy resin. If the base resin is an epoxy resin, the thermosetting component constitutes the epoxy thermosetting component together with the curing agent (epoxy curing agent) and curing accelerator (epoxy curing accelerator) described below.

Examples of the epoxy resin include bifunctional epoxy resins such as bisphenol A epoxy resin, bisphenol F epoxy resin, modified bisphenol A epoxy resin, modified bisphenol F epoxy resin, biphenyl epoxy resin, and phenol novolak epoxy resin. Examples include trifunctional or higher functional epoxy resins such as cresol novolac type epoxy resin, trishydroxyphenylmethane type epoxy resin, tetraphenylolethane type epoxy resin, and dicyclopentadiene type epoxy resin. These epoxy resins can be used alone or in combination of two or more.

Preferable examples include cresol novolak type epoxy resin and trishydroxyphenylmethane type epoxy resin.

Specific examples of cresol novolac type epoxy resins include compounds represented by the following general formula (1), and specific examples of trishydroxyphenylmethane type epoxy resins include compounds represented by the following general formula (2). Examples include compounds.

Note that n each independently represents the degree of polymerization of the monomer.

The epoxy equivalent of the epoxy resin is, for example, 10 g/eq. Above, preferably 100g/eq. or more, and for example, 300g/eq. Below, preferably 250g/eq. It is as follows.

The proportion of the base resin (preferably epoxy resin) in the resin is, for example, 5% by mass or more and, for example, 50% by mass or less.

The curing agent is a component (preferably an epoxy resin curing agent) that cures the above-mentioned main ingredient by heating. Examples of the curing agent include phenolic resins such as phenol novolac resins.

The ratio of the curing agent is such that, if the main resin is an epoxy resin and the curing agent is a phenol resin, the total amount of hydroxyl groups in the phenol resin is, for example, 0.7 equivalent or more per 1 equivalent of epoxy group in the epoxy resin. , preferably 0.9 equivalent or more, for example, 1.5 equivalent or less, preferably 1.2 equivalent or less. Specifically, the blending number of the curing agent is, for example, 70 parts by mass or more and 150 parts by mass or less, based on 100 parts by mass of the main agent.

The curing accelerator is a catalyst (thermal curing catalyst) (preferably an epoxy resin curing accelerator) that accelerates curing of the base resin by heating, and is, for example, an organic phosphorus compound such as 2-phenyl-4-methyl. Examples include imidazole compounds such as -5-hydroxymethylimidazole (2P4MHZ). Preferably, imidazole compounds are used. The blending number of the curing accelerator is, for example, 0.05 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the main agent.

The volume ratio of the resin in the magnetic composition (first magnetic sheet 5) is the remainder of the volume ratio of the magnetic particles 48 described above, and specifically, for example, 10 volume% or more, preferably 20 volume% or more. For example, it is 80% by volume or less, preferably 50% by volume or less.

Note that known additives (for example, dispersants, rheology control agents, etc.) can be blended into the magnetic composition in appropriate proportions.

The first magnetic sheet 5 is prepared by blending magnetic particles 48 and a resin and uniformly mixing them to prepare a magnetic composition. At this time, a varnish of the magnetic composition is prepared using a solvent (organic solvent) if necessary. Thereafter, varnish is applied to a release film (not shown) and dried to prepare (manufacture) the first magnetic sheet 5.

The thickness of the first magnetic sheet 5 is appropriately set so as to ensure a thickness T3 of the magnetic layer 21, which will be described later.

The release cushion sheet 6 is heat-pressed between the second press plate 11 and the first magnetic sheet 5 while suppressing adhesion (pressure-sensitive adhesion) between them in the first pressing process described next. Later, it is a release sheet that can release the magnetic layer 21 from the second press plate 11. Moreover, the release cushion sheet 6 distributes the pressure of the second press plate 11 in accordance with the shapes of the plurality of wiring parts 4 and applies it to the first magnetic sheet 5 during hot pressing in the first pressing step. It is also a cushion sheet for causing deformation in the first magnetic sheet 5 and making the first magnetic sheet 5 follow the shape of the plurality of wiring sections 4 .

The release cushion sheet 6 has a sheet shape extending in the plane direction, and has a first release surface 22 as one surface in the thickness direction and a second release surface 23 as the other surface in the thickness direction.

The first mold release surface 22 can contact the second press plate 11 (described later) in a planar manner. The first mold release surface 22 is a flat surface along the surface direction.

The second release surface 23 can contact the first magnetic surface 18 of the first magnetic sheet 5 in a planar manner. The second mold release surface 23 is disposed opposite to the first mold release surface 22 on the other side in the thickness direction with an interval therebetween. The second mold release surface 23 is parallel to the first mold release surface 22 and is a flat surface along the surface direction.

The release cushion sheet 6 includes a first layer 31, a second layer 32, and a third layer 33 in this order on one side in the thickness direction. Preferably, the release cushion sheet 6 includes only a first layer 31, a second layer 32, and a third layer 33.

The first layer 31 is located on the othermost side of the release cushion sheet 6 in the thickness direction. Thereby, the first layer 31 forms the second mold release surface 23. That is, the first layer 31 is a release layer (first release layer) for the first magnetic sheet 5 (specifically, the magnetic layer 21 after hot pressing). The first layer 31 is a thin film (skin film) having a shape extending along the surface direction. Further, the first layer 31 is a covering layer (outer shell layer) that covers a second layer 32, which will be described next, from the other side in the thickness direction. The other surface in the thickness direction of the first layer 31 (the surface corresponding to the second release surface 23) may be subjected to an appropriate peeling treatment.

The first layer 31 can follow and come into contact with the first magnetic surface 18 of the first magnetic sheet 5 during the heat pressing in the next first pressing step, but its thickness substantially changes before and after the heat press. It has physical properties that do not Moreover, the first layer 31 is a layer that can be stretched in the plane direction (specifically, in the first direction) in the above-described heat press. Note that the first layer 31 is harder than the second layer 32, which will be described next, at the hot press temperature (for example, 110° C.) in the first pressing step.

Specifically, the tensile storage modulus E' at 110° C. of the first layer 31 is, for example, 50 MPa or more, preferably 100 MPa or more, more preferably 150 MPa or more, and, for example, 300 MPa or less. The tensile storage modulus E' is determined by dynamic viscoelasticity measurement under the conditions of a frequency of 1 Hz and a heating rate of 10° C./min. The tensile storage modulus E' of the second layer 32 and the release cushion sheet 6, which will be described later, is also determined in the same manner.

Note that the temperature of 110° C. for specifying the tensile storage modulus E' of the first layer 31 is a temperature that is assumed to be the temperature at which the first magnetic sheet 5 is hot pressed in the first pressing step or a temperature close thereto. The temperature of 110° C. for specifying the tensile storage modulus E' of the second layer 32 and the third layer 33 is also the same as that described above for the first layer 31.

Further, the melting point of the first layer 31 is high, for example, a temperature exceeding the temperature of hot press (for example, 110°C), specifically, 200°C or higher, preferably 210°C or higher, more preferably, The temperature is 220°C or higher and 250°C or lower. The melting point of the first layer 31 is measured with a differential scanning calorimeter. Note that the melting points of the second layer 32 and third layer 33, which will be described later, are also measured in the same manner as described above.

Examples of the material for the first layer 31 include non-thermal fluid materials that do not flow at least in the first direction due to heat pressing in the first pressing step described below.

The non-thermofluidic material contains, for example, aromatic polyester, polyolefin, etc. as a main component.

Examples of the aromatic polyester include polyalkylene terephthalates such as polybutylene terephthalate (PBT) and polyethylene terephthalate (PET), with PBT being preferred.

Polyolefins include homopolymers and/or copolymers of α-olefins such as ethylene, propylene, 1-butene, 2-butene, 2-methylpropene, 4-methyl-1-pentene, and are preferably poly(4 -methyl-1-pentene).

Preferably, aromatic polyester is used as the non-thermofluidic material.

The thickness of the first layer 31 is, for example, 50 μm or less, preferably 25 μm or less, and is, for example, 5 μm or more, preferably 10 μm or more.

The second layer 32 is disposed on one side of the first layer 31 in the thickness direction, and is an intermediate layer sandwiched between the first layer 31 and the third layer 33 in the release cushion sheet 6 . The second layer 32 is a fluidized layer that flows in the first direction and the thickness direction during hot pressing in the first step to cause the first layer 31 to follow the first magnetic surface 18 of the first magnetic sheet 5.

The second layer 32 is a flexible layer that is softer than the first layer 31, and specifically can be deformed during hot pressing in the first pressing step. Specifically, the tensile storage modulus E' of the second layer 32 at 110°C is lower than the tensile storage modulus E' of the first layer 31 at 110°C. More specifically, the tensile storage modulus E' at 110°C of the second layer 32 is, for example, 50 MPa or less, preferably 40 MPa or less, more preferably 30 MPa or less, still more preferably 20 MPa or less, and , for example, 5 MPa or more. The tensile storage modulus E' of the first layer 31 is determined by dynamic viscoelasticity measurement of the insulating layer under the conditions of a frequency of 1 Hz and a heating rate of 10° C./min.

If the tensile storage elastic modulus E' at 110° C. of the second layer 32 is below the above-mentioned upper limit, it can be flexibly deformed during hot pressing in the first pressing step, and specifically, it can be deformed to follow the plurality of wiring parts 4. You can transform it as you like.

Also, the ratio of the tensile storage modulus E' of the second layer 32 at 110°C to the tensile storage modulus E' of the first layer 31 at 110°C (tensile storage modulus E' of the second layer 32 at 110°C/ The tensile storage modulus E') of the first layer 31 at 110° C. is, for example, less than 1, preferably 0.5 or less, more preferably 0.1 or less, and, for example, 0.005 or more. be.

Note that the tensile storage modulus E' of the second layer 32 at 110°C is, for example, lower than or the same as the tensile storage modulus E' of the first magnetic sheet 5 at 110°C.

Further, the melting point of the second layer 32 is lower than that of the first layer 31, for example, the temperature below the heat press temperature (for example, 110°C), specifically, less than 105°C, preferably , below 100°C, and, for example, above 50°C.

Examples of the material for the second layer 32 include a thermofluidic material that flows in the first direction and the thickness direction by heat pressing in the first pressing step described below. The thermofluidic material contains, for example, an olefin-(meth)acrylate copolymer, an olefin-vinyl acetate copolymer, etc. as a main component.

Examples of olefin-(meth)acrylate copolymers include ethylene-methyl (meth)acrylate copolymers, ethylene-ethyl (meth)acrylate copolymers, ethylene-propyl (meth)acrylate copolymers, and ethylene-butyl (meth)acrylate copolymers. -Alkyl (meth)acrylate copolymers, such as propylene-alkyl (meth)acrylate copolymers, such as propylene-methyl (meth)acrylate copolymers.

Examples of olefin-vinyl acetate copolymers include ethylene-vinyl acetate copolymers.

Preferably, the thermofluidic material includes an olefin-(meth)acrylate copolymer, preferably an ethylene-alkyl(meth)acrylate copolymer, more preferably an ethylene-methyl(meth)acrylate copolymer, and even more preferably, Mention may be made of ethylene-methyl methacrylate copolymers.

The thickness T2 of the second layer 32 is, for example, 30 μm or more, preferably 50 μm or more, more preferably 100 μm or more, and also, for example, 300 μm or less, preferably 200 μm or less, more preferably 150 μm or less. .

The ratio of the thickness T2 of the second layer 32 to the thickness T1 of the wiring section 4 (thickness T2 of the second layer 32/thickness T1 of the wiring section 4) is 0.3 or more, preferably 0.5 or more, Further, it is, for example, 3.0 or less, preferably 2.0 or less.

If the ratio (T2/T1) of the thickness T2 of the second layer 32 to the thickness T1 of the wiring portion 4 is equal to or greater than the above-mentioned lower limit, the magnetic layer 21 having a desired shape (described later) can be formed in the first step. I can do it.

Further, the ratio of the thickness T2 of the second layer 32 to the thickness of the first layer 31 is, for example, 2 or more, preferably 5 or more, more preferably 7 or more, and, for example, 15 or less.

The third layer 33 is disposed on one surface of the second layer 32 in the thickness direction, and is located on the most one side of the release cushion sheet 6 in the thickness direction. Thereby, the third layer 33 forms the first mold release surface 22 . Further, the third layer 33 is a mold release layer (second mold release layer) for the second press plate 11. The shape, physical properties, material, and thickness of the third layer 33 are the same as those of the first layer 31.

The ratio of the thickness T2 of the second layer 32 to the sum of the thickness of the first layer 31 and the thickness of the third layer 33 is, for example, 1.5 or more, preferably 3 or more, more preferably 4 or more, Further, for example, it is 8 or less.

The thickness of the release cushion sheet 6 is the sum of the thickness of the first layer 31, the thickness T2 of the second layer 32, and the thickness of the third layer 33, and is, for example, 50 μm or more, preferably 100 μm or more, and For example, it is 500 μm or less, preferably 200 μm or less.

The release cushion sheet 6 may be a commercially available product; for example, a release film OT series (manufactured by Sekisui Chemical Co., Ltd.) such as release film OT-A or release film OT-E may be used. It will be done.

Thereafter, the printed circuit board 40, the first magnetic sheet 5, and the release cushion sheet 6 are sandwiched between the two press plates 20 in that order.

The two press plates 20 consist of a first press plate 10 and a second press plate 11 spaced apart from each other in the thickness direction. Each of the first press plate 10 and the second press plate 11 has a shape extending in the surface direction.

The first press plate 10 and/or the second press plate 11 are equipped with a heat source (not shown) so that the first magnetic sheet 5 and the release cushion sheet 6 can be heated.

The first press plate 10 and the second press plate 11 move relative to each other so as to press the above-described insulating layer 2, the plurality of wiring parts 4, the first magnetic sheet 5, and the release cushion sheet 6 in the thickness direction. It is configured.

The first press plate 10 has a first press surface 7 extending along the surface direction. The first press surface 7 is a flat surface along the surface direction. For example, the first press plate 10 is fixed to a fixing member (not shown) so as not to move in the thickness direction.

The second press plate 11 has a second press surface 8 parallel to the first press surface 7 . The second press plate 11 is connected to a power device (not shown) and is movable in the thickness direction.

In order to sandwich the printed circuit board 40, the first magnetic sheet 5, and the release cushion sheet 6 between the two press plates 20, the printed circuit board 40 and the first magnetic sheet are sandwiched between the two press plates 20. 5 and a release cushion sheet 6 are arranged (inserted). At this time, for example, the second insulating surface 9 comes into contact with the first pressing surface 7.

Thereby, the sandwiching step is performed.

After that, as shown in FIG. 2B, a first pressing step is performed. In the first pressing step, the printed circuit board 40, the first magnetic sheet 5, and the release cushion sheet 6 are hot pressed using two press plates 20.

For example, the second press plate 11 is moved (lowered) closer to the first press plate 10 to press the second press plate 11 against the first magnetic sheet 5 via the release cushion sheet 6 ( press).

At the same time, the first magnetic sheet 5 and the release cushion sheet 6 are heated by the heat source.

The press pressure is, for example, 0.1 MPa or more, preferably 0.3 MPa or more, and is, for example, 10 MPa or less, preferably 5 MPa or less.

The heating temperature is, for example, higher than the melting point of the second layer 32 and lower than the melting point of the first layer 31. Further, the heating temperature is specifically, for example, 100°C or higher, preferably 105°C or higher, and is, for example, 190°C or lower, preferably 150°C or lower.

The pressing time is, for example, 10 seconds or more, preferably 20 seconds or more, and is, for example, 1000 seconds or less, preferably 100 seconds or less.

In this first press step, as shown by the arrow in FIG. 1 and FIG. 2A, when the second press plate 11 starts to move relative to the first press plate 10, the first mold release surface 22 and the second press surface 8 In addition, the second mold release surface 23 and the first magnetic surface 18 are in contact with each other, and the second magnetic surface 19 and the opposing surface 15 are in contact with each other. In other words, in the first press plate 10, the insulating layer 2, the wiring part 4, the first magnetic sheet 5, the release cushion sheet 6, and the second press plate 11, members adjacent in the thickness direction are in contact with each other (in close contact with each other). Then, the second press plate 11 moves further (hot pressing starts).

Then, when projected in the thickness direction, the overlapping portion 34 that overlaps the opposing surface 15 in the release cushion sheet 6 is formed by the opposing surface 15 and the second press surface 8, as shown by the horizontal arrow in FIG. 2A. It is pressed while being narrowed in the thickness direction (narrowing pressure).

Note that, when projected in the thickness direction, a non-overlapping portion 35 that does not overlap with the opposing surface 15 in the release cushion sheet 6 is a region in which the second magnetic surface 19 does not contact the opposing surface 15 and the first insulating surface 3 Since it is separated from the exposed surface 36 exposed from the plurality of wiring parts 4, it is not subjected to the above-mentioned narrow pressure.

Then, the thermofluidic material in the overlapping portion 34 of the second layer 32 flows (is pushed out) (deforms) (specifically, plastically deforms) toward the non-overlapping portion 35 . Then, as shown by the vertical arrow in FIG. 2A, the flow pressure based on the flow (extrusion) of the thermofluidic material from the above-described overlapping portion 34 increases in the non-overlapping portion 35. The flow pressure in the non-overlapping portion 35 acts on both sides in the thickness direction.

As shown in FIGS. 2A and 2B, among the fluid pressures, the fluid pressure that acts on the other side in the thickness direction pushes (pushes down) the first layer 31 in the non-overlapping portion 35 to the other side in the thickness direction, and The extruded portion 38 of the first magnetic sheet 5 that faces the non-overlapping portion 35 in the thickness direction is pushed out (pushed down) to the other side in the thickness direction via the first magnetic sheet 31 . Note that the fluid pressure acting on one side in the thickness direction (arrow indicated by a broken line) acts on the third layer 33 facing the non-overlapping portion 35, but as described above, the third layer 33 Since the third layer 33 is strongly supported by the third layer 33, the third layer 33 is not deformed.

Thereafter, the extrusion (pushing down) of the extruded portion 38 based on the above-described fluid pressure continues until the second magnetic surface 19 of the extruded portion 38 comes into contact with the side surface 17 and the exposed surface 36.

Then, as the second magnetic surface 19 of the extruded portion 38 comes into contact with the side surface 17 and the exposed surface 36, a magnetic layer 21 filling between the plurality of wiring portions 4 is formed (molded) as shown in FIG. 1C. ) to be done.

Note that due to this hot pressing, in the second layer 32, the overlapping portion 34 becomes thinner than before the hot pressing, and the non-overlapping portion 35 becomes thicker than before the hot pressing.

On the other hand, in the first layer 31 and the third layer 33, both the overlapping portion 34 and the non-overlapping portion 35 do not substantially change before and after hot pressing. On the other hand, the first layer 31 expands in the first direction as the second layer 32 deforms.

In short, after hot pressing, the second release surface 23 of the release cushion sheet 6 has a shape corresponding to the magnetic layer 21 (first magnetic sheet 5 after molding).

Note that the magnetic layer 21 (first magnetic sheet 5) after hot pressing is, for example, B-stage.

The thickness T3 of the magnetic layer 21 is, for example, 10 μm or more, preferably 30 μm or more, and is, for example, 500 μm or less, preferably 300 μm or less. Note that the thickness T3 of the magnetic layer 21 is defined as the length in the thickness direction between the facing surface 15 of the wiring portion 4 and the top portion 28 (described later) of the magnetic layer 21.

Further, the ratio of the thickness T3 of the magnetic layer 21 to the thickness T1 of the wiring portion 4 (thickness T3 of the first magnetic layer/thickness T1 of the wiring portion 4) is, for example, 0.3 or more, preferably 0.4 or more. , more preferably 0.5 or more, and, for example, 5.0 or less. If the ratio is equal to or higher than the above-mentioned lower limit, the magnetic layer 21 can reliably fill the space between the adjacent wiring parts 4 in the first pressing step.

Thereby, a magnetic layer 21 formed (molded) into a predetermined shape is obtained from the first magnetic sheet 5. Thereby, the magnetic wired circuit board 1 including the wired circuit board 40 and the magnetic layer 21 is obtained.

The magnetic layer 21 is formed to fill the space between the plurality of wiring sections 4 and to cover the opposing surface 15 of the wiring section 4 .

Specifically, the magnetic layer 21 has a convex portion 25 and a concave portion 26 .

A plurality of convex portions 25 are formed corresponding to the plurality of wiring portions 4. The plurality of convex portions 25 are arranged on the opposing surface 15 of the plurality of wiring portions 4 . Further, the plurality of convex portions 25 are arranged adjacent to each other at intervals in the first direction. Each of the plurality of convex portions 25 has a shape that protrudes toward one side in the thickness direction. The convex portion 25 has a convex surface 27 spaced apart from the opposing surface 15 of the wiring portion 4 on one side in the thickness direction.

The convex surface 27 overlaps the opposing surface 15 when projected in the thickness direction, and is spaced from the opposing surface 15 on one side in the thickness direction. The convex surface 27 has only one apex 28 . The top portion 28 is located on the most one side in the thickness direction of the convex surface 27, that is, located on the farthest part from the opposing surface 15.

The convex surface 27 has a curved shape that gradually falls (sinks) toward the other side in the thickness direction as it goes from the top 28 toward both sides in the first direction. The degree of depression (sinking) of the convex surface 27 toward the other side in the thickness direction increases as the distance from the top portion 28 to both sides in the second direction increases.

The recess 26 is located between the plurality of protrusions 25 corresponding to the plurality of wiring parts 4, and has a shape that sinks toward the other side in the thickness direction with respect to the adjacent protrusions 25.

A part of the recess 26 , specifically, the other side in the thickness direction fills the gap between the adjacent wiring parts 4 . That is, a portion of the recessed portion 26 described above overlaps with the wiring portion 4 when projected in the first direction.

On the other hand, the remaining part of the recessed part 26, specifically, the part on one side in the thickness direction, does not overlap with the wiring part 4 when projected in the first direction. It is arranged on one side in the thickness direction of the projection plane of No. 4.

The recess 26 has a recess 29 spaced from the exposed surface 36 of the first insulating surface 3 on one side in the thickness direction.

The concave surface 29 is continuous with the edge of the convex surface 27 in the first direction. Concave surface 29 faces at least exposed surface 36 , and preferably faces both exposed surface 36 and side surface 17 . The concave surface 29 has a substantially curved shape that sinks (concave) toward the other side in the thickness direction. Concave surface 29 has a bottom 30 .

The bottom portion 30 is located on one side in the thickness direction of the concave surface 29 with respect to the virtual plane S passing through the facing surfaces 15 of the adjacent wiring portions 4 . That is, the bottom portion 30 is spaced apart from the above-described virtual plane S on one side in the thickness direction. Further, the bottom portion 30 is located at the portion of the concave surface 29 that is closest to the exposed surface 36. In other words, the bottom portion 30 is the bottommost portion of the concave surface 29 (the portion located on the othermost side in the thickness direction).

Thereafter, if necessary, the magnetic layer 21 is C-staged (completely cured), for example, by heating. Specifically, the magnetic wiring circuit board 1 is placed in a heating furnace by further heating or by releasing the above-described press.

In this way, a C-staged (completely cured) magnetic layer 21 is prepared.

This magnetic wiring circuit board 1 is used for, for example, wireless power transmission (wireless power supply and/or wireless power reception), wireless communication, sensors, passive components, and the like.

According to this method of manufacturing the magnetic wired circuit board 1, as shown in FIG. The magnetic layer 21 can be easily formed at one time by the first pressing step of hot pressing the cushion sheet 6.

Moreover, the tensile storage modulus E' of the second layer 32 in the release cushion sheet 6 at 110°C is lower than that of the first layer 31 at 110°C. When performing the pressing process, the second layer 32 becomes softer than the first layer 31, so that the second layer 32 flows more easily than the first layer 31. The first magnetic sheet 5 can be pushed out between the plurality of wiring sections 4. Therefore, in the first pressing step, it is possible to reliably form the magnetic layer 21 that fills between the plurality of wiring parts 4 and covers the facing surface 15 of the wiring parts 4.

In this method for manufacturing the magnetic wiring circuit board 1, if the tensile storage modulus E' at 110° C. of the second layer 32 is as low as 20 MPa or less, the The two layers 32 can flow reliably. Therefore, the second layer 32 can push the first magnetic sheet 5 between the plurality of wiring sections 4. As a result, the spaces between the plurality of wiring sections 4 can be reliably filled with the magnetic layer 21, and the magnetic wiring circuit board 1 having high inductance can be obtained.

In this method of manufacturing the magnetic wiring circuit board 1, if the ratio of the thickness T2 of the second layer 32 to the thickness T1 of the wiring portion 4 is as high as 0.5 or more, the thickness T3 of the magnetic layer 21 is can be set to a thickness that is half or more of the thickness T1 of the wiring portion 4. Therefore, the first magnetic sheet 5 on the opposing surface 15 of the wiring section 4 can be flexibly hot-pressed by the second layer 32 having a thickness T2 that is more than half the thickness T1 of the wiring section 4. A sufficient thickness of the corresponding magnetic layer 21 can be ensured. As a result, the opposing surface 15 of the wiring portion 4 can be reliably covered with the magnetic layer 21 .

In this method for manufacturing the magnetic wiring circuit board 1, the release cushion sheet 6 further includes a third layer 33 having a tensile storage modulus E' higher than the tensile storage modulus E' at 110° C. of the second layer 32. When performing the first pressing step at the above-described temperature, the hard third layer 33 can suppress deformation of the release cushion sheet 6 to one side in the thickness direction. Therefore, the first pressing step can be performed reliably.

In this method of manufacturing the magnetic wired circuit board 1, the ratio of the thickness T3 of the magnetic layer 21 to the thickness T1 of the wiring portion 4 is as high as 0.5 or more. The thickness can be set to half or more of the thickness T1. Therefore, the magnetic layer 21 that is relatively thick with respect to the wiring portion 4 can be formed while reliably filling the spaces between the plurality of wiring portions 4. As a result, the effective magnetic permeability between the wiring parts 4 can be improved, and the magnetic wiring circuit board 1 having high inductance can be obtained.

Further, in this magnetic wired circuit board 1, the convex portion 25 has only one apex 28, the concave portion 26 has a shape concave in a curved shape toward the other side in the thickness direction, and the adjacent wiring Since the bottom portion 30 is located on one side in the thickness direction with respect to the virtual plane S passing through the facing surface 15 of the portion 4, the wiring portion 4 is The effective magnetic permeability of the surrounding area can be improved.

Specifically, as shown in FIG. 3, the magnetic particles 48 are oriented in the convex portion 25 along the first direction or in a direction that gently curves so as to fall from the top portion 28 toward the other side in the thickness direction. The bottom portion 30 of the recess 26 is oriented along the first direction or a direction that gently curves up toward one side in the thickness direction toward the two adjacent convex portions 25, and the recess 26, between the circumferential side surfaces 17 of the two wiring portions 4, it is oriented along the circumferential side surface 17, and in the portion covering the exposed surface 36, it is oriented along the exposed surface 36 (first direction). Therefore, in this magnetic layer 21, a smooth magnetic path along the convex portions 25 and the concave portions 26 is formed.

As a result, this magnetic wiring circuit board 1 has high inductance .

<Modified example>
In each of the following modified examples, the same reference numerals are given to the same members and steps as in the first embodiment described above, and detailed explanation thereof will be omitted. Moreover, each modification example can produce the same effects as the first embodiment except as otherwise specified.

As shown in FIG. 1A, in the first embodiment, the release cushion sheet 6 includes the third layer 33; There can only be 32. In this case, preferably, the release cushion sheet 6 consists of only the first layer 31 and the second layer 32.

Among the first embodiment and the above-mentioned modifications, the first embodiment is preferable. In the first embodiment, as shown in FIG. 1A, since the release cushion sheet 6 includes the third layer 33, as shown in FIG. 1B, when performing the first pressing step at 110° C., the hard third layer The layer 33 can suppress deformation of the release cushion sheet 6 to one side in the thickness direction. Therefore, the first pressing step can be performed reliably.

As shown in FIG. 1A, in the first embodiment, in the release cushion sheet 6, adjacent layers among the first layer 31, second layer 32, and third layer 33 are in contact with each other. However, in a modification (not shown), the layers that are adjacent in the thickness direction may be spaced apart from each other and prepared separately.

For example, although not shown, another release sheet may be interposed between the second press plate 11 and the release cushion sheet 6. The release sheet (not shown) is harder than the second layer 32 in the release cushion sheet 6, for example.

The release cushion sheet 6 can also be used by laminating a plurality of them in the thickness direction.

As shown by the imaginary line in FIG. 1C, the magnetic wiring circuit board 1 can also include a third magnetic layer 37 disposed on the other surface of the insulating layer 2 in the thickness direction.

Furthermore, the insulating layer 2 may be a magnetic insulating layer containing magnetic particles.

Further, in the first embodiment, the magnetic layer 21 is a single layer, but although not shown, it may be a multilayer. In this case, the plurality of first magnetic sheets 5 are sandwiched between the plurality of wiring parts 4 and the mold release cushion sheet 6, and the plurality of first magnetic sheets 5 are hot-pressed in one first pressing step to make the magnetic Form layer 21. In this modification, the total thickness T3 of the plurality of first magnetic sheets 5 in the sandwiching step is the same as the thickness T3 of the single-layer magnetic layer 21 in the first embodiment.

Further, the proportion of the magnetic particles 48 in the magnetic layer 21 may be uniform in the magnetic layer 21, and may increase or decrease as the distance from each wiring section 4 increases.

<Second embodiment>
In the following second embodiment, the same reference numerals are given to the same members and steps as in the above-described first embodiment and its modifications, and detailed explanation thereof will be omitted. Further, the second embodiment can be appropriately combined with the first embodiment and its modification. Further, the second embodiment can provide the same effects as the first embodiment and its modified examples, except as otherwise specified.

In the first embodiment, as shown in FIGS. 1A and 1B, the magnetic layer 21 is formed from the first magnetic sheet 5 in one first pressing step.

In the second embodiment, as shown in FIGS. 4A to 5E, in addition to the first pressing step of hot pressing the first magnetic sheet 5, a second pressing step of hot pressing the second magnetic sheet 45 is provided. That is, in the second embodiment, the magnetic layer 21 is formed in two pressing steps.

As shown in FIG. 5C, the thickness T3 of the first magnetic layer 41 is allowed to be thinner than the thickness T1 of the wiring part 4, and specifically, for example, 100 μm or less, further, 80 μm or less, or even , 60 μm or less, and, for example, 5 μm or more. The ratio of the thickness T3 of the first magnetic layer 41 to the thickness T1 of the wiring portion 4 is, for example, less than 0.5, more preferably 0.3 or less, and, for example, 0.05 or more.

Further, in the first pressing step, the content ratio of the magnetic particles 48 in the first magnetic sheet 5 (magnetic composition) can be set lower than that in the first embodiment, for example, less than 60% by volume, preferably is less than 55 volume %, more preferably 50 volume % or less, and for example, 15 volume % or more. If the content ratio of the magnetic particles 48 in the first magnetic sheet 5 is less than the above-mentioned upper limit, the flexible first magnetic sheet 5 is easily deformed by the heat pressing in the first pressing step, and the side surface 17 and the exposed surface 36 are easily deformed. can be reliably contacted. Note that the content ratio of the resin is the remainder of the content ratio of the magnetic particles 48 described above.

In the first pressing step, as shown in FIGS. 4A to 5A, the first magnetic layer 41 having the above-described shape is formed (molded) from the first magnetic sheet 5. Note that this first magnetic layer 41 is preferably still in the B stage.

Note that, as shown in FIGS. 4B and 5C, in the first pressing process, a first magnetic printed circuit board 51 including a printed circuit board 40 (insulating layer 2 and wiring part 4) and a first magnetic layer 41 is Manufactured. In the second embodiment, the first magnetic wiring circuit board 51 is configured such that, for example, when the bottom portion 30 is located at the same position as the virtual surface S or on the other side in the thickness direction (described later), the first magnetic wiring circuit board 51 is It is an intermediate part for manufacturing a second magnetic wiring circuit board 52 (described later) (product) (see FIG. 5E) obtained in the form of a first magnetic layer 41 and a second magnetic layer 42 (described later). ) (see Figure 5E).

As shown in FIG. 5C, if the first magnetic sheet 5 is thin as described above, the first magnetic layer 41 fills only the other side in the thickness direction of the gap between the adjacent wiring parts 4 ( In other words, it is allowed that one side in the thickness direction is not filled) and that the bottom portion 30 is located at the same position as the virtual surface S or on the other side in the thickness direction.

As shown in FIG. 5D, the second pressing step is performed after the first pressing step.

Specifically, first, the hot press in the first press step is released (released), and then the second press plate 11 is separated from the release cushion sheet 6. That is, the release cushion sheet 6 is released from the magnetic layer 21 . In other words, the release cushion sheet 6 is separated from one side of the first magnetic layer 41 . Thereafter, the release cushion sheet 6 is taken out (pulled out) from between the first magnetic layer 41 and the second press plate 11.

Separately, a release cushion sheet 6 (as described above, a release cushion sheet 6 different from the release cushion sheet 6 taken out (pulled out)) is prepared.

At the same time, a second magnetic sheet 45 is prepared.

The material and physical properties of the second magnetic sheet 45 are similar to those of the first magnetic sheet 5.

In particular, the content ratio of the magnetic particles 48 in the second magnetic layer 42 can be set higher than the content ratio of the magnetic particles 48 in the first magnetic sheet 5, for example. The ratio of the content ratio of magnetic particles 48 in the second magnetic layer 42 to the content ratio of magnetic particles 48 in the first magnetic sheet 5 is, for example, more than 1, preferably 1.1 or more, preferably 1.15 or more. and is, for example, 2 or less, preferably 1.5 or less.

Specifically, the content ratio of the magnetic particles 48 in the second magnetic sheet 45 is, for example, more than 50 volume %, preferably 55 volume % or more, more preferably 60 volume % or more, for example, 90 volume %. It is as follows. If the content ratio of the magnetic particles 48 in the second magnetic sheet 45 exceeds the above-mentioned lower limit, the inductance of the magnetic wiring circuit board 1 can be improved by the second magnetic layer 42 containing the magnetic particles 48 at a high content ratio. .

Subsequently, in the second pressing step, the first magnetic printed circuit board 51, the second magnetic sheet 45, and the release cushion sheet 6 are hot pressed using the two press plates 20.

First, the second magnetic sheet 45 and the release cushion sheet 6 are placed in order on one side of the first magnetic layer 41 in the first magnetic wiring circuit board 51. Specifically, the second magnetic sheet 45 and the release cushion sheet 6 are arranged (inserted) between the first magnetic layer 41 and the second press plate 11.

Thereafter, the first magnetic wiring circuit board 51, the second magnetic sheet 45, and the release cushion sheet 6 are hot-pressed using the two press plates 20. The conditions for the second press step are the same as those for the first press step.

As a result, the second magnetic layer 42 is formed (molded) from the second magnetic sheet 45 on one side of the first magnetic layer 41 in the thickness direction of the first magnetic wiring circuit board 51 . This second magnetic layer 42 is, for example, B stage. Thereby, the magnetic layer 21 is obtained, which includes the first magnetic layer 41 and the second magnetic layer 42 in order on one side in the thickness direction. The magnetic layer 21 is preferably formed from only the first magnetic layer 41 and the second magnetic layer 42.

For example, the thickness T4 of the second magnetic layer 42 is such that the ratio of the sum (T3+T4) of the thickness T3 of the first magnetic layer 41 and the thickness T4 of the second magnetic layer 42 to the thickness T1 of the wiring portion 4 is 0.5 or more. , is preferably set to be 0.6 or more, and for example, 5.0 or less, preferably 3.0 or less. The ratio (T4/T3) of the thickness T4 of the second magnetic layer 42 to the thickness T3 of the first magnetic layer 41 is, for example, 1.5 or more, preferably 2.0 or more, and, for example, 40 or less. , preferably 30 or less. Specifically, the thickness T4 of the second magnetic layer 42 is, for example, 10 μm or more, preferably 20 μm or more, and is, for example, 450 μm or less, preferably 250 μm or less.

Thereby, a second magnetic printed circuit board 52 including the printed circuit board 40 and the magnetic layer 21 is obtained. Note that the second magnetic wiring circuit board 52 includes the first magnetic wiring circuit board 51 and the second magnetic layer 42 .

Thereafter, if necessary, if the first magnetic layer 41 and the second magnetic layer 42 are in the B stage, the first magnetic layer 41 and the second magnetic layer 42 are made into a C stage (completely hardened).

The method for manufacturing the second magnetic wiring circuit board 52 further includes a second pressing step, as shown in FIG. 5D, and therefore includes the first magnetic layer 41 and the second magnetic layer 42 ), a thick magnetic layer 21 can be reliably formed. Therefore, the magnetic permeability between the wiring parts 4 can be improved, and the second magnetic wiring circuit board 52 having high inductance can be obtained.

Further, if the ratio of the thickness T3 of the first magnetic layer 41 to the thickness T1 of the wiring portion 4 is low, such as less than 0.5, the first magnetic layer 41 tends to become thinner, as shown in FIG. It tends to be difficult to fill the spaces between the wiring parts 4 with the first magnetic layer 41.

However, in this second method of manufacturing the magnetic wiring circuit board 52, the ratio of the total thickness T3 of the first magnetic layer 41 and the thickness T4 of the second magnetic layer to the thickness T1 of the wiring portion 4 is 0.5 or more. If the thickness is high, the spaces between the plurality of wiring sections 4 can be reliably filled with the thick magnetic layer 21 including the first magnetic layer 21 and the second magnetic layer 21. As a result, the second magnetic wiring circuit board 52 having high inductance can be obtained.

According to the second method for manufacturing the magnetic wiring circuit board 52, if the content ratio of the magnetic particles 48 in the first magnetic sheet 5 is lower than the content ratio of the magnetic particles 48 in the second magnetic sheet 45, The first magnetic sheet 5, which is more flexible than the second magnetic sheet 45, is reliably placed between the plurality of wiring sections 4, and then the second magnetic sheet 45, which is more rigid than the first magnetic sheet 5, is placed between the plurality of wiring sections 4. Also, by arranging it in the first magnetic layer 41 that has already been arranged between the plurality of wiring parts 4, a magnetic layer including the first magnetic layer 41 and the second magnetic layer 42 can be formed between the plurality of wiring parts 4. 21, it can be filled.

Furthermore, the second magnetic wiring circuit board 52 is formed by the second magnetic layer 21 formed from the second magnetic sheet containing magnetic particles 48 at a higher content rate than the content rate of the magnetic particles 48 in the first magnetic sheet 5. can improve the inductance of

<Modified example>
In each of the following modified examples, the same reference numerals are given to the same members and steps as in the second embodiment described above, and detailed explanation thereof will be omitted. Moreover, each modification can be combined as appropriate. Furthermore, each modification example can produce the same effects as the second embodiment except as otherwise specified.

The release cushion sheet 6 used in the first press step was taken out, another release cushion sheet 6 was placed, and the sheet was subjected to hot pressing in the second press step. However, a common release cushion sheet 6 can also be used in the first press process and the second press process. That is, the release cushion sheet 6 used in the first press process can be reused in the second press process.

Further, in the second embodiment, the second magnetic sheet 45 is a single layer, but in a modified example, it may be a multilayer. Preferably, the number of layers is 3 or more and 10 or less.

Moreover, the second pressing step can also be performed multiple times. For example, although not shown, if the second pressing step is performed twice, the magnetic layer 21 is formed by a total of three pressing steps. In this case, the first magnetic layer 41 is formed by a first pressing step (first pressing step) in which the first magnetic sheet 5 is hot-pressed, and then the second magnetic sheet 45 is attached to the first magnetic layer 41. The first magnetic layer 41 and the second magnetic layer 42 are formed by a second pressing step (second pressing step) in which the magnetic layer is hot pressed.

After that, another second magnetic sheet 45 is prepared, and a second pressing step (third pressing step) is performed in which the second magnetic sheet 45 is hot pressed against the second magnetic layer 42 . This step is the second of two second pressing steps, and another second magnetic sheet 45 is used together with the second magnetic sheet 45 in the first second pressing step. "include.

Further, in the second press step, the second magnetic layer 42 is formed from another second magnetic sheet 45. The second magnetic layer 42 formed in the second second press step and the second magnetic layer 42 formed in the first second press step are both included in the "second magnetic layer" in the present invention. It will be done. Note that the thickness T4 of the second magnetic layer 42 is the total thickness of all the second magnetic layers 42. Specifically, in the above example, the total thickness of the second magnetic layer 42 formed in the first second press step and the second magnetic layer 42 formed in the second second press step is the thickness T4 of the second magnetic layer 42.

In the first and second embodiments, the wiring portion 4 has a quadrilateral shape in cross-section, but in this modification, it has a substantially circular shape in cross-section, as shown in FIGS. 6C and 7.

The wiring section 4 includes a conductive wire 43 and a second insulating layer 44 covering the conductive wire 43.

The conducting wire 43 has a substantially circular cross-sectional shape that shares a central axis with the wiring portion 4 .

The second insulating layer 44 is an insulating layer different from the insulating layer 2. The second insulating layer 44 covers the entire outer circumferential surface (circumferential surface) of the conducting wire 43 and has a substantially annular shape in cross section that shares a central axis (center) with the wiring section 4 .

The material of the second insulating layer 44 is the same as that of the insulating layer 2. The second insulating layer 44 may be composed of a single layer or a plurality of layers.

The diameter D of the wiring portion 4 corresponds to the thickness T1 described above. Note that the ratio of the thickness of the second insulating layer 44 to the diameter D of the wiring portion 4 is, for example, 0.005 or more and 0.1 or less.

In the manufacturing method of this modification, as shown in FIG. 6A, in the sandwiching step, first, a plurality of wiring portions 4 are arranged on the first insulating surface 3 of the insulating layer 2. Specifically, the other edge of the wiring portion 4 in the thickness direction is brought into contact with the first insulating surface 3 .

In the first pressing step, as shown in FIG. 6B, the second magnetic surface 19 of the first magnetic sheet 5 is formed so that the first semicircular arc 46 of the wiring section 4 (including the other edge in the thickness direction of the wiring section 4, (a semicircular arc) located on the other side of the direction. However, the second magnetic surface 19 does not contact the other edge in the thickness direction of the wiring portion 4 that contacts the first insulating surface 3 .

Moreover, if the first pressing step is carried out, the recesses 26 filling between the plurality of wiring parts 4 and the second semicircular arc 47 of the wiring part 4 (continuous to one side in the thickness direction of the first semicircular arc 46, A magnetic layer 21 is formed (molded) including a convex portion 25 that includes the other edge of the wiring portion 4 in the thickness direction and follows a semicircular arc located on one side in the thickness direction.

As shown in FIG. 7 , the magnetic particles 48 are oriented along the circumferential direction of the wiring portion 4 in the peripheral region (nearby region) of the wiring portion 4 . A substantially annular magnetic path along the circumferential direction is formed.

Further, in the above-mentioned modification, as shown in FIG. 6A, the wiring part 4 is arranged on the insulating layer 2, and then, as shown in FIGS. 6C and 7, the magnetic wiring circuit board 1 including the insulating layer 2 is obtained. However, for example, although not shown, the wiring portion 4 is placed on the second release film as an example of the insulating layer 2, and then the first magnetic sheet 5 is placed on the second release film so as to cover the wiring portion 4. The second release film can be placed on one side in the thickness direction of the second release film, and then the second release film can be peeled off from the first magnetic sheet 5 and the wiring section 4 .

The second release film has, for example, a sheet shape extending in the plane direction, and specifically has one side and the other side facing each other in the thickness direction. The material of the second release film is not particularly limited, and examples thereof include resins such as PET. One side of the second release film may be subjected to a known peeling treatment. The thickness of the second release film is, for example, 1 μm or more, preferably 10 μm or more, and is, for example, 2000 μm or less, preferably 500 μm or less.

The magnetic wiring circuit board 1 obtained in this modification includes a plurality of wiring parts 4 and a magnetic layer 21 (first magnetic sheet 5), and does not include a second release film.

In the modified examples shown in FIGS. 6A to 7, the wiring portion 4 and the conductive wire 43 have a substantially circular shape in cross-sectional view, but are not limited to this, and may also have a substantially rectangular shape, a substantially trapezoidal shape, etc., although not shown. It will be done. In this modification, although not shown, the second insulating layer 44 covers the entire outer peripheral surface of the wiring section 4.

Furthermore, the magnetic wiring circuit board 1 described above can include a third magnetic layer 37 provided on the other surface of the magnetic layer 21 so as to cover the other edge of the wiring portion 4 in the thickness direction. In this magnetic wiring circuit board 1 , the entire circumferential surface (outer circumferential surface) of the wiring portion 4 is covered with the first magnetic sheet 5 composed of the first magnetic sheet 5 and the third magnetic layer 37 .

Moreover, the first embodiment, the second embodiment, and each modification can be combined as appropriate.

Examples and Comparative Examples are shown below to further specifically explain the present invention. Note that the present invention is not limited to the Examples and Comparative Examples. In addition, the specific numerical values such as compounding ratios (ratios), physical property values, parameters, etc. used in the following descriptions are the corresponding compounding ratios (ratios) described in the above "Details of Carrying Out the Invention". ), physical property values, parameters, etc. can be replaced with the upper limit (a numerical value defined as "less than" or "less than") or the lower limit (a numerical value defined as "more than" or "exceeding").

Example 1
(Pinching process)
A printed circuit board 40 including an insulating layer 2 and a plurality of wiring portions 4 disposed on a first insulating surface 3 thereof was prepared.

In the printed circuit board 40, the insulating layer 2 has a first support layer 12 made of polyethylene terephthalate, a pressure-sensitive adhesive layer 13 made of acrylic resin, and a second support layer 14 made of polyimide resin on one side in the thickness direction. Prepare accordingly.

In the printed circuit board 40, the plurality of wiring parts 4 are made of copper and have a thickness T1 of 100 μm. The length of the facing surfaces 15 in the first direction is 245 μm, and the interval in the first direction between the facing surfaces 15 in adjacent wiring portions 4 is 190 μm. The length of the supported surfaces 16 in the first direction is 336 μm, and the distance between the supported surfaces 16 in adjacent wiring sections 4 in the first direction is 100 μm.

Separately, a first magnetic sheet 5 and a release cushion sheet 6 were prepared.

The first magnetic sheet 5 was prepared as a B-stage sheet by first preparing a first magnetic composition according to the recipe in Table 1 and forming it into a sheet shape.

As the release cushion sheet 6, a release film OT-A160 (manufactured by Sekisui Chemical Co., Ltd.) was prepared as is.

The release cushion sheet 6 has a thickness of 160 μm and includes a first layer 31 with a thickness of 20 μm, a second layer 32 with a thickness T2 of 120 μm, and a third layer 33 with a thickness of 20 μm.

The first layer 31 and the third layer 33 have a melting point of 223°C, a tensile storage modulus E' at 110°C of 190 MPa, and contain polybutylene terephthalate as a main component.

The second layer 32 has a melting point of 80° C., a tensile storage modulus E' at 110° C. of 5.6 MPa, and the material contains ethylene-methyl methacrylate copolymer as a main component.

Subsequently, the printed circuit board 40, the first magnetic sheet 5, and the release cushion sheet 6 were sandwiched between the two press plates 20.

(First press step: Manufacture of first magnetic wiring circuit board 51)
The printed circuit board 40, the first magnetic sheet 5, and the release cushion sheet 6 are heated using two press plates 20 under press conditions of 2 MPa (equivalent to 2 kN), 110° C., and 60 seconds. Pressed.

As a result, the first magnetic layer 41 was formed (molded) from the first magnetic sheet 5. The thickness T3 of the first magnetic layer 41 was 10 μm. As a result, a first magnetic printed circuit board 51 including the printed circuit board 40 and the first magnetic layer 41 was manufactured.

(Second pressing step: Manufacturing of second magnetic wiring circuit board 52)
First, the release cushion sheet 6 used in the first pressing step was taken out.

Separately, a new release cushion sheet 6 (release OT-A160 similar to that prepared in the first press step) was prepared.

The second magnetic sheet 45 was prepared as a B-stage sheet by first preparing a second magnetic composition according to the recipe in Table 1 and forming it into a sheet shape.

Next, four second magnetic sheets 45 and a newly prepared release cushion sheet 6 were inserted between the first magnetic layer 41 and the second press plate 11 on the first magnetic wiring circuit board 51. .

The first magnetic wiring circuit board 51, the second magnetic sheet 45, and the release cushion sheet 6 were pressed using two press plates 20 at a press pressure of 2 MPa (equivalent to 2 kN), at 110° C., and for 60 seconds. Heat pressed.

As a result, the second magnetic layer 42 from the second magnetic sheet 45 was formed (molded) on one surface of the first magnetic layer 41 in the thickness direction of the first magnetic wiring circuit board 51. A magnetic layer 21 consisting of a first magnetic layer 41 and a second magnetic layer 42 was formed. The thickness T4 of the second magnetic layer 42 was 100 μm.

In this way, a second magnetic wiring circuit board 52 including the first magnetic layer 41 and the second magnetic layer 42 was manufactured. Note that the second magnetic wired circuit board 52 includes a wired circuit board 40 and a magnetic layer 21.

Example 2 to Comparative Example 4
A second magnetic wiring circuit board 52 was manufactured in the same manner as in Example 1, except that the type, thickness, etc. of the release cushion sheet 6 were changed according to Table 2.

Note that TPX (release cushion sheet 6) in Comparative Examples 1 and 2 is a release sheet (manufactured by Mitsui Chemicals, Inc.) made of methylpentene resin (melting point 235° C.).

Moreover, the MRA (mold release cushion sheet 6) in Comparative Examples 3 and 4 is a mold release sheet (manufactured by Mitsubishi Chemical Corporation) made of polyethylene terephthalate resin (melting point 260° C.).

(evaluation)
[Inductance]
The inductance of the wiring section 4 in the second magnetic wiring circuit board 52 was measured.
[SEM observation]
A cross section of the second magnetic wiring circuit board 52 along the thickness direction and the first direction was observed by SEM. The image processing diagrams are shown in FIGS. 8 to 15.

(Consideration)
In Comparative Examples 1 to 4, the release cushion sheet 6 does not include the second layer 32.

In Comparative Examples 1 to 3, the first magnetic sheet 5 and the second magnetic sheet 45 could not be pressed uniformly in each of the first pressing step and the second pressing step, and the first Two apexes 28 are formed on the convex surface 27 of the convex portion 25 by the contraction force in the direction.

In particular, in Comparative Example 2, the bottom portion 30 is pointed toward the other side in the thickness direction.

Furthermore, in Comparative Example 4, the tensile storage modulus E' of the release cushion sheet 6 at 110° C. is excessively high. Therefore, a large stress is applied to the first magnetic sheet 5 and the second magnetic sheet 45 corresponding to the non-overlapping portion 35, and as a result, the bottom portion 30 is located on the other side in the thickness direction with respect to the virtual plane S.

In contrast to these comparative examples, in each example, the release cushion sheet 6 includes the second layer 32, and the tensile storage modulus E' of the second layer at 110°C is the same as the tensile storage modulus of the third layer at 110°C. It is lower than the rate E'. Therefore, the convex surface 27 has only one apex 28. Further, the concave surface 29 has a shape that is curved toward the other side in the thickness direction, and has a bottom portion 30 located on one side in the thickness direction with respect to the virtual surface S. As a result, each example has higher inductance than each comparative example.

1 Magnetic wiring circuit board 2 Insulating layer 3 First insulating surface 4 Wiring portion 5 First magnetic sheet 6 Release cushion sheet 15 Opposing surface 20 Two press plates 21 Magnetic layer 25 Convex portion 26 Concave portion 27 Convex surface 28 Top portion 29 Concave surface 30 Bottom portion 31 First layer 32 Second layer 33 Third layer 41 First magnetic layer 42 Second magnetic layer 45 Second magnetic sheet 48 Magnetic particles 52 Second magnetic wiring circuit board T1 Wiring portion thickness T2 Second layer thickness T3 Thickness of the first magnetic layer T4 Thickness of the second magnetic layer

Claims (9)

Two press plates are used to press an insulating layer, a plurality of wiring parts arranged at intervals from each other in a predetermined direction on one side in the thickness direction of the insulating layer, a first magnetic sheet, and a release cushion sheet. a pinching process of sandwiching the pieces in order, and
A first pressing step of hot pressing the insulating layer, the plurality of wiring parts, the first magnetic sheet, and the release cushion sheet on the press plate,
In the first pressing step, a first magnetic layer is formed from the first magnetic sheet so as to fill between the plurality of wiring parts and to cover one surface of the wiring part in the thickness direction,
The thickness T1 of the plurality of wiring parts is 50 μm or more,
The first magnetic sheet includes anisotropic magnetic particles,
The magnetic layer including the first magnetic layer is
a plurality of convex portions disposed on opposing surfaces of the plurality of wiring portions and protruding toward one side in the thickness direction;
a recessed portion located between the plurality of convex portions and recessed toward the other side in the thickness direction with respect to the adjacent convex portions;
The convex portion has only one apex located on the most one side in the thickness direction,
The recess has a substantially curved shape that sinks toward the other side in the thickness direction, and is located on one side in the thickness direction with respect to a virtual plane passing through the opposing surfaces of the adjacent wiring parts. has a bottom that
The release cushion sheet is
a first layer;
a second layer disposed on one side of the first layer in the thickness direction,
A method for manufacturing a magnetic wiring circuit board, wherein a tensile storage modulus E' of the second layer at 110°C is lower than a tensile storage modulus E' of the first layer at 110°C. 2. The method for manufacturing a magnetic printed circuit board according to claim 1, wherein the second layer has a tensile storage modulus E' at 110° C. of 20 MPa or less. 3. The method of manufacturing a magnetic wired circuit board according to claim 1, wherein a ratio of the thickness T2 of the second layer to the thickness T1 of the wiring portion is 0.5 or more. The release cushion sheet further includes a third layer disposed on one side of the second layer in the thickness direction,
Any one of claims 1 to 3, wherein the tensile storage modulus E' of the second layer at 110°C is lower than the tensile storage modulus E' of the third layer at 110°C. A method for manufacturing a magnetic wiring circuit board as described in . 5. The magnetic wired circuit board according to claim 1, wherein the ratio of the thickness T3 of the first magnetic layer to the thickness T1 of the wiring portion is 0.5 or more. Production method. A second press for hot pressing the insulating layer, the plurality of wiring parts, the first magnetic layer formed in the first step, the second magnetic sheet, and the release cushion sheet on the press plate. With additional processes,
5. The method for manufacturing a magnetic wiring circuit board according to claim 1, wherein in the second pressing step, a second magnetic layer is formed from the second magnetic sheet. The ratio of the thickness T3 of the first magnetic layer to the thickness T1 of the wiring portion is less than 0.5,
7. The magnetic material according to claim 6, wherein a ratio of the sum of the thickness T3 of the first magnetic layer and the thickness T4 of the second magnetic layer to the thickness T1 of the wiring portion is 0.5 or more. A method for manufacturing printed circuit boards. The second magnetic sheet contains magnetic particles,
The method for manufacturing a magnetic wiring circuit board according to claim 6 or 7, wherein the content ratio of magnetic particles in the first magnetic sheet is lower than the content ratio of magnetic particles in the second magnetic sheet. . an insulating layer;
a plurality of wiring portions arranged at intervals from each other in a predetermined direction on one side in the thickness direction of the insulating layer;
a magnetic layer that is filled between the plurality of wiring parts and covers an opposing surface that is arranged opposite to the one surface in the thickness direction of the wiring part at a distance;
The magnetic layer is
a plurality of convex portions disposed on the opposing surfaces of the plurality of wiring portions and protruding toward one side in the thickness direction;
a recessed portion located between the plurality of convex portions and recessed toward the other side in the thickness direction with respect to the adjacent convex portions;
The convex portion has only one apex located on the most one side in the thickness direction,
The recess has a substantially curved shape that sinks toward the other side in the thickness direction, and is located on one side in the thickness direction with respect to a virtual plane passing through the opposing surfaces of the adjacent wiring parts. 1. A magnetic wiring circuit board, characterized in that it has a bottom portion.

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