Patent ID: 12224093

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

A multilayer magnetic sheet400according to one embodiment of the present disclosure will be described with reference toFIGS.1to13. The multilayer magnetic sheet400is used for a contactless-type charging device. The multilayer magnetic sheet400may be used in a power feeder of a charging device or may be used in a power receiver.

In the present embodiment, as an example, a multilayer magnetic sheet400is used for contactless charging of a device that consumes more power than an information processing device such as a smartphone or an electronic device. For example, the multilayer magnetic sheet400is used for contactless charging of a moving body such as an automobile. Note that the multilayer magnetic sheet400may be used for contactless charging of an information processing device, an electronic device, or the like. The multilayer magnetic sheet400is also applicable to a transport vehicle such as a forklift and an AGV, a railway, a tram, or the like.

FIG.1is a plan view for explaining the structure of the multilayer magnetic sheet400.FIG.6is a cross-sectional view for explaining the structure of the multilayer magnetic sheet400.

In the multilayer magnetic sheet400, as shown inFIGS.1and6, a large number of layers in each of which a plurality of magnetic strips300formed in a band shape are arranged side by side in a plate shape are stacked. The multilayer magnetic sheet400includes one or more of each of first layer310, second layer320, and third layer330described below.

As shown inFIG.2A, the first layer310includes a plurality of magnetic strips300formed in a band shape having a short side and a long side. The plurality of magnetic strips300are arranged such that long sides300L are adjacent to each other to be arranged in a plate shape.

As shown inFIG.2B, the second layer320includes a plurality of magnetic strips300formed in a band shape having a short side and a long side. The plurality of magnetic strips300are arranged such that long sides300L are adjacent to each other to be arranged in a plate shape. The direction in which the long side300L of the second layer320extends intersects the direction in which the long side300L of the first layer310extends.

As shown inFIG.3, the third layer330includes a plurality of magnetic strips300formed in a band shape having a short side and a long side. The plurality of magnetic strips300are arranged such that long sides300L are adjacent to each other to be arranged in a plate shape. The direction in which the long side of the third layer330extends is the same as the direction in which the long side300L of the first layer310(indicated by a broken line in the drawing) extends.

Furthermore, the position of the long side300L in the first layer310and the position of the long side300L in the third layer330are separated by 0.5 mm or more in the direction in which the short side extends. The distance of the separation is indicated by D. Note that a partial cross-sectional view for explaining the structures of the first layer310and the third layer330is shown inFIG.4.FIG.4shows an example in which the second layer320is provided between the first layer310and the third layer330.

The multilayer magnetic sheet400may include one or more fourth layers340described below.

As shown inFIG.5, the fourth layer340includes a plurality of magnetic strips300formed in a band shape having a short side and a long side. The plurality of magnetic strips300are arranged such that long sides are adjacent to each other to be arranged in a plate shape. The direction in which the long side300L of the fourth layer340extends is the same as the direction in which the long side300L of the second layer320(indicated by a broken line in the drawing) extends.

Furthermore, the position of the long side300L in the second layer320and the position of the long side300L in the fourth layer340are separated by 0.5 mm or more in the direction in which the short side extends. The distance of the separation is indicated by D.

By adopting a structure including one or more of each of the first layer310, the second layer320, and the third layer330, a magnetic gap continuous in the stacking direction of the magnetic strips300can be suppressed from being formed.

In addition, by adopting a structure including one or more of each of the first layer310, the second layer320, the third layer330, and the fourth layer340, a magnetic gap continuous in the stacking direction of the magnetic strips300can be suppressed from being formed.

The order in which the first layer310to the third layer330are arranged or the order in which the first layer310to the fourth layer340are arranged can be appropriately set, and the number of each of the layers to be used can also be appropriately set.

The thickness direction is also referred to as “a direction in which the first layer310, the second layer320, and the third layer330are stacked”.

As shown inFIG.1, the multilayer magnetic sheet400has a plate shape or a sheet shape formed in a rectangular shape in a plan view. The plurality of magnetic strips300constituting the first layer310, the second layer320, the third layer330, and the fourth layer340are arranged such that the long sides300L are adjacent to each other, and are arranged side by side in the direction in which the short sides300S extend. The interval between the magnetic strips300arranged side by side in the direction in which the short sides300S extend is preferably 0 mm or more and 5 mm or less.

The number of arranged short sides300S of the magnetic strips300constituting each layer in the extending direction is preferably 2 or more and 20 or less. The number may be 20 or more. In the present embodiment, as an example, five magnetic strips300are arranged.

In the present embodiment, as an example, one magnetic strip300is arranged in the direction in which the long side300L extends. Note that a plurality of magnetic strips300may be arranged in the direction in which the long side300L extends.

In the present embodiment, as an example, a length L of the magnetic strip300in the direction in which the long side300L extends is in the range of 100 mm or more and 1000 mm or less, and a width Wr in the direction in which the short side300S extends is in the range of 10 mm or more and 100 mm or less. Note that the length L of the magnetic strip300in the direction in which the long side300L extends may be outside the range described above, and the width Wr in the direction in which the short side300S extends may be outside the range described above.

In the present embodiment, as an example, the length L of the multilayer magnetic sheet400is in the range of 100 mm or more and 1000 mm or less, and the width Ws is in a range of 100 mm or more and 1000 mm or less.

Here, the length L is a dimension in a direction in which the long side300L of the magnetic strip300in the first layer310constituting the multilayer magnetic sheet400extends, and the width Ws is a dimension in a direction in which the short side300S of the magnetic strip300in the first layer310extends. Note that the length L of the multilayer magnetic sheet400may be outside the range described above, and the width Ws may be outside the range described above.

In the multilayer magnetic sheet400of the present disclosure, for example, the magnetic strips300are arranged with the positions of the long sides300L shifted as with the first layer310and the third layer330. Therefore, when the magnetic strips300having the same dimensions are used, the end faces of the magnetic strips300are not aligned on the end face side of the multilayer magnetic sheet400. As thus described, the end faces of the magnetic strips300may not be aligned.

The magnetic strips300having different dimensions (dimensions in the width direction) may be used, and the end faces of the magnetic strips300may be aligned on the end face side of the multilayer magnetic sheet400.

As shown inFIG.6, the multilayer magnetic sheet400has a configuration in which the first layer310to the third layer330are stacked in the thickness direction in a cross-sectional view. In addition, the multilayer magnetic sheet400has a configuration in which the first layer310to the fourth layer340are stacked in the thickness direction. Note that the multilayer magnetic sheet400may include a layer having a configuration other than the first layer310to the fourth layer340.

The multilayer magnetic sheet400shown inFIG.6is provided with a resin sheet15.

The resin sheet15may not be stacked on a first stacking end401or a second stacking end402. In the first stacking end401or the second stacking end402, the magnetic strip300may be exposed, or for example, an outer layer material selected from an amorphous alloy strip, a nanocrystalline alloy strip, another magnetic material or a metal foil such as aluminum, a resin sheet, or the like may be attached.

The number of magnetic strips stacked in the thickness direction in the multilayer magnetic sheet400is preferably 10 or more in total. The number is preferably 15 or more, more preferably 20 or more, and still more preferably 25 or more. The upper limit of the number of magnetic strips is not particularly set. A required number of layers may be stacked. For example, 200 or less is preferable.

The first layer310and the second layer320are stacked such that the direction in which the long side300L of the first layer310extends and the direction in which the long side300L of the second layer320extends intersect each other. More preferably, the intersecting angle is 90±1 degrees.

The first layer310and the fourth layer340, the third layer330and the second layer320, and the third layer330and the fourth layer340are also stacked so as to intersect each other in the same manner. More preferably, the intersecting angle is 90±1 degrees.

As a material for forming the magnetic strip300, an alloy with an alloy composition of an Fe-based or Co-based alloy can be used, and a nanocrystalline alloy or an amorphous alloy can be used. In particular, the magnetic strip300is preferably a strip formed using a nanocrystal alloy as a material (hereinafter also referred to as a “nanocrystalline alloy strip”).

The nanocrystalline alloy strip is obtained by subjecting an amorphous alloy strip capable of nanocrystallization to a heat treatment for nanocrystallization. It is preferable to perform heat treatment for nanocrystallization in a state where tension is applied to the amorphous alloy strip capable of nanocrystallization. Note that the strip formed using an amorphous alloy as a material is also referred to as an “amorphous alloy strip” or a “non-crystalline alloy strip”.

The nanocrystalline alloy strip preferably has a composition represented by the following general formula.
(Fe1-aMa)100-x-y-z-α-β-γCuxSiyBzM′αM″βXγ(atomic percent)  General Formula:

In the above general formula, M is Co and/or Ni, M′ is at least one element selected from the group consisting of Nb, Mo, Ta, Ti, Zr, Hf, V, Cr, Mn, and W, M” is at least one element selected from the group consisting of Al, a platinum group element, Sc, a rare earth element, Zn, Sn, and Re, X is at least one element selected from the group consisting of C, Ge, P, Ga, Sb, In, Be, and As, and a, x, y, z, α, β, and γ satisfy 0≤a≤0.5, 0.1≤x≤3, 0≤y≤30, 0≤z≤25, 5≤y+z≤30, 0≤α≤20, 0≤β≤20, and 0≤γ≤20, respectively.

Preferably, in the general formula, a, x, y, z, α, β, and γ satisfy 0≤a≤0.1, 0.7≤x≤1.3, 12≤y≤17, 5≤z≤10, 1.5≤α≤5, 0≤β≤1, and 0≤γ≤1, respectively.

In the present embodiment, as an example, the magnetic strip300is a strip (FT-3 manufactured by Hitachi Metals, Ltd. (now, Proterial, Ltd.)) that is a Fe—Cu—Nb—Si—B based nanocrystal alloy. Note that the magnetic strip300may be a nanocrystalline alloy strip having another composition represented by the above general formula or may be an amorphous alloy strip.

When the magnetic strip300is a nanocrystalline alloy strip, the magnetic strip300is mechanically more brittle than when the magnetic strip is an amorphous alloy strip. When the magnetic strip300is a nanocrystalline alloy strip, the crack21can be formed with a small external force at the time of directly applying an external force to the magnetic strip300to form the crack21.

When the magnetic strip300is a nanocrystalline alloy strip, the crack21can be formed without substantially forming unevenness on the surface of the magnetic strip300. Thus, the planar state of the magnetic strip300can be made favorable. The temporal change in the shape of the magnetic strip300, generated after the magnetic strip300and an adhesive layer10are attached to each other, is reduced. The temporal change in the magnetic characteristics of the magnetic strip300can be suppressed.

As the magnetic strip300, for example, an alloy strip, manufactured by roll rapid cooling and having a thickness of 100 μm or less can be used. The thickness of the magnetic strip300is preferably 50 μm or less, more preferably 30 μm or less, particularly preferably 25 μm or less, and particularly preferably 20 μm or less. Since it is difficult to handle the magnetic strip300when the thickness is thin, the thickness of the magnetic strip300is preferably 5 μm or more, and more preferably 10 μm or more.

In the multilayer magnetic sheet400, the magnetic strips300are stacked and bonded to each other.

In the multilayer magnetic sheet400of the present disclosure, it is preferable to use, as the magnetic strip300, a magnetic sheet100described later in which an adhesive layer10is formed on one surface of the magnetic strip300. The magnetic sheet100includes the adhesive layer10and can be bonded with another magnetic strip300, and the magnetic strips300can be easily stacked and bonded.

FIG.12is a cross-sectional view of the magnetic sheet100cut in the width direction for explaining the structure of the magnetic sheet100.

The magnetic sheet100can be used as the magnetic strip300in the structure described above. As shown inFIG.12, the magnetic sheet100has a configuration in which one adhesive layer10, one resin sheet15, and one magnetic strip300are stacked. When the magnetic strips300are stacked, the resin sheet15may be peeled off from the magnetic sheet100, and another magnetic strip300may be bonded to the adhesive layer10.

The adhesive layer10is a member to which the magnetic strip300is attached. Furthermore, the adhesive layer10is a member formed in an elongated shape, for example, a film-like member formed in a rectangular shape. The adhesive layer10is mainly provided with a support11and an adhesive12.

The support11is a band-shaped film member formed in an elongated shape, for example, a film member formed in a rectangular shape. The support11is formed using a flexible resin material. As the resin material, polyethylene terephthalate (PET) can be used.

The adhesive12is provided in a film form or a layer form on each of a first surface11A and a second surface11B of the support11.

As the adhesive12, for example, a pressure sensitive adhesive can be used. For example, a known adhesive such as an acrylic adhesive, a silicone-based adhesive, a urethane-based adhesive, a synthetic rubber, or a natural rubber can be used as the adhesive12. The acrylic adhesive is preferable as the adhesive12because acrylic adhesive is excellent in heat resistance and moisture resistance and has a wide range of materials that can be bonded.

The adhesive12is provided in a layer form on each of the first surface11A and the second surface11B of the support11. In the present embodiment, as an example, the adhesive12is provided on the entire surfaces of the first surface11A and the second surface11B of the support11.

The magnetic strip300is a strip formed in an elongated band shape using a magnetic material. A crack21is formed in the magnetic strip300. The magnetic strip300is divided into a plurality of small pieces22by the crack21. In other words, the magnetic strip300includes a plurality of small pieces22. The crack21refers to a magnetic gap formed in the magnetic strip300and includes, for example, a break and/or a fissure of the magnetic strip300.

By forming the crack21in the magnetic strip300, the Q factor can be easily improved when the multilayer magnetic sheet400is used as a magnetic body for an inductor. When the multilayer magnetic sheet400is used as a magnetic body for magnetic shielding, the eddy current loss can be easily reduced by dividing the current path of the magnetic strip300.

The magnetic strip300is bonded to the adhesive12of the adhesive layer10. In the present embodiment, the magnetic strip300is bonded to the adhesive12provided on the first surface11A of the adhesive layer10. The magnetic strip300and the adhesive layer10preferably have shapes that satisfy the relationship of the following formula.
0.2 mm≤(widthA−widthB)≤3 mm

The width A is a dimension related to the adhesive layer10, and more preferably a dimension related to a region provided with the adhesive12to which the magnetic strip300is bonded in the adhesive layer10. The width B is a dimension related to the magnetic strip300. When the adhesive12is provided on the entire surface of the support11of the adhesive layer10, the width A is a dimension related to the adhesive layer10or the support11.

Here, the lower limit of (width A−width B) is preferably 0.5 mm, and more preferably 1.0 mm. The upper limit of (width A−width B) is preferably 2.5 mm and more preferably 2.0 mm.

The magnetic strip300and the adhesive layer10are preferably disposed to satisfy a relationship of another following formula.
0 mm<gapaand 0 mm<gapb

In the magnetic sheet100of the present disclosure, the width A of the adhesive layer10provided with the adhesive12in the adhesive layer10is larger than the width B of the magnetic strip300. At the time of attaching the magnetic strip300to the adhesive layer10, even when meandering occurs in the adhesive layer10or the magnetic strip300, the adhesive12of the adhesive layer10can be easily disposed on the entire surface of the magnetic strip300.

By setting the value obtained by subtracting the width B from the width A to 0.2 mm or more, a portion where the adhesive is not disposed on the magnetic strip300can be easily prevented from occurring at the time of attaching the magnetic strip300to the adhesive layer10. By setting the value obtained by subtracting the width B from the width A to 3 mm or less, the interval between the magnetic strips300can be easily prevented from increasing when the magnetic sheet100is disposed as the magnetic strip300. As a result, when the magnetic sheets100are arranged in parallel, the interval (magnetic gap) between the magnetic strips300can be easily prevented from increasing.

The gap a and the gap b are distances from the end of the adhesive layer10to the end of the magnetic strip300. Specifically, the gap a is a distance from a first adhesive layer end10X of the adhesive layer10to a first strip end20X of the magnetic strip300. The gap b is a distance from a second adhesive layer end10Y of the adhesive layer10to a second strip end20Y of the magnetic strip300.

The first strip end20X is an end of the magnetic strip300on the same side as the first adhesive layer end10X. The second adhesive layer end10Y is an end of adhesive layer10opposite to the first adhesive layer end10X. The second strip end20Y is an end of the magnetic strip300on the same side as the second adhesive layer end10Y.

The width A, the width B, the gap a, and the gap b are dimensions in a direction intersecting the longitudinal direction of the magnetic strip300, more preferably in a direction orthogonal thereto. The longitudinal direction of the magnetic strip300and the longitudinal direction of the adhesive layer10are the same direction.

As an example, a method of manufacturing the magnetic sheet100in a case where the length of the magnetic strip300in the longitudinal direction is 20,000 m will be described below. Furthermore, as an example, the width A, which is a dimension related to the adhesive layer10or the support11, is 32 mm, the width B, which is a dimension related to the magnetic strip300, is 30 mm, and the width A−the width B is 2 mm.

The resin sheet15is a film-like member formed using a resin and is a member also referred to as a protective film, a release film, or a liner. The resin sheet15is a member used for protecting the magnetic strip300and the multilayer magnetic sheet400.

The resin sheet15has a function of preventing an unnecessary increase in the crack21to be described later (or a crack connecting a plurality of cracks21in a mesh form) due to the application of an unintended external force to the magnetic strip300. Furthermore, the resin sheet15has a function of suppressing the small pieces22of the magnetic strip300from falling off and a function of suppressing the magnetic strip300from rusting.

Moreover, the resin sheet15has a function of suppressing the occurrence of unnecessary deformation when the multilayer magnetic sheet400is processed into a predetermined shape. The unnecessary deformation is, for example, formation of unevenness on the surface. The resin sheet15may be stacked together with the adhesive layer10as described above or may be stacked alone.

The resin sheet15is preferably a film-like member formed using a resin, and more preferably a member formed using a resin with elasticity. In this case, the generation of unevenness on the surface of the magnetic strip300is easily suppressed by the elastic force of the resin sheet15.

Even when unevenness is generated on the surface of the magnetic strip300, the unevenness of the magnetic strip300tends to be flat due to the elastic force of the resin sheet15. The planar state of the magnetic strip300can be made to a favorable state with few unevenness. The temporal change in the magnetic characteristics of the multilayer magnetic sheet400can be easily reduced.

As the resin sheet15, a resin having a lower limit of a tensile elastic modulus of 0.1 GPa can be used. When the tensile elastic modulus of the resin is 0.1 GPa or more, the above effect can be easily obtained sufficiently. The lower limit of the tensile elastic modulus is preferably 0.5 GPa, and more preferably 1.0 GPa.

The upper limit of the tensile elastic modulus of the resin is preferably 10 GPa. When the upper limit exceeds 10 GPa, the deformation of the alloy strip may be suppressed when the crack21to be described later is formed. The upper limit of the tensile elastic modulus is preferably 9 GPa, and more preferably 8 GPa.

The resin sheet15preferably has a thickness of 1 μm or more and 100 μm or less. When the thickness of the resin sheet15increases, the multilayer magnetic sheet400is less likely to be deformed. As a result, it may be difficult to dispose the multilayer magnetic sheet400along the curved surface or the bent surface.

When the thickness of the resin sheet15is less than 1 μm, the resin sheet15is more likely to be deformed. As a result, the handling of the resin sheet15becomes difficult, and the function of supporting the magnetic strip300by the resin sheet15may not be obtained sufficiently. When the resin sheet15is a protective film, the strength of the resin sheet15becomes weak, and the function of protecting the magnetic strip300and the like may not be sufficient.

As the resin of the resin sheet15, it is possible to use, for example, polyethylene terephthalate (PET), polyimide, polyetherimide, polyethylene naphthalate, polypropylene, polyethylene, polystyrene, polycarbonate, polysulfone, polyetherketone, polyvinyl chloride, polyvinyl alcohol, a fluororesin, an acrylic resin, cellulose, or the like. Polyamide and polyimide are particularly preferable as the resin for forming the resin sheet15from the viewpoint of heat resistance and dielectric loss.

FIG.7is a schematic view for explaining a method for manufacturing the magnetic sheet100.

The magnetic sheet100can be used as the magnetic strip300of the multilayer magnetic sheet400described with reference toFIGS.1to6. The magnetic sheet100is manufactured using a manufacturing apparatus500shown inFIG.7. The manufacturing apparatus500is mainly provided with a first unwinding roll510, a first winding roll520, a second unwinding roll530, an attaching roll540, a crack roll550, a flattening roll560, and a third winding roll570from upstream to downstream in the manufacturing process. The manufacturing apparatus500may further be provided with a plurality of guide roll580. Note that the guide roll580can be disposed as necessary even at a position not described.

FIG.8is a cross-sectional view for explaining a configuration of a laminate supplied from the first unwinding roll510.

As shown inFIG.8, a laminate in which the resin sheet15is stacked on the first surface11A and the second surface11B of the adhesive layer10is wound around the first unwinding roll510. The resin sheet15disposed on the first surface11A is a protective sheet, and the resin sheet15disposed on the second surface11B is also referred to as a “liner”. The resin sheet15disposed on the first surface11A is thinner than the resin sheet15disposed on the second surface11B.

FIG.9is a cross-sectional view for explaining the configuration of the laminate supplied from the first unwinding roll510and from which the resin sheet15has been peeled off.

As shown inFIG.9, the resin sheet15disposed on the first surface11A is peeled off from the laminate unwound from the first unwinding roll510. As shown inFIG.7, the peeled resin sheet15is wound onto the first winding roll520.

FIG.10is a cross-sectional view for explaining the configuration of the magnetic strip300supplied from the second unwinding roll530.

The laminate from which the resin sheet15disposed on the first surface11A has been peeled off is guided to the attaching roll540by the plurality of guide rolls580. The magnetic strip300unwound from the second unwinding roll530has further been guided to the attaching roll540. As shown inFIG.10, there is no crack21formed in the magnetic strip300guided to the attaching roll540.

Here, a method for manufacturing the magnetic strip300unwound from the second unwinding roll530will be described. For example, a case where the magnetic strip300is a nanocrystalline alloy will be described. The magnetic strip300is manufactured by a manufacturing method including: a step of rapidly cooling a molten alloy to obtain an amorphous alloy strip capable of nanocrystallization; and a heat treatment step of heat-treating the amorphous alloy strip at a crystallization onset temperature or higher to form fine crystal grains.

The rapid cooling described above is performed by a single roll method in which a molten metal is discharged onto a rotating cooling roll and rapidly cooled and solidified. The magnetic strip300has an elongated shape in which a direction along the rotation direction of the cooling roll is a longitudinal direction. The length of the magnetic strip300in the longitudinal direction may be, for example, 20,000 m.

The temperature of the heat treatment varies depending on the alloy composition, but is generally 450° C. or higher. The fine crystal grains are, for example, Fe having a body-centered cubic lattice structure with solid solution of Si or the like. The analysis of the fine crystal grains can be performed using X-ray diffraction and a transmission electron microscope.

In the nanocrystalline alloy, at least 50 vol % of the nanocrystalline alloy is occupied by fine crystal grains having an average of the largest dimension of the grain size of 100 nm or less. A portion other than the fine crystal grains in the nanocrystalline alloy is mainly amorphous. The proportion of the fine crystal grains may be substantially 100 vol %.

FIG.11is a cross-sectional view for explaining a state in which the magnetic strip300has been bonded to the adhesive layer10by the attaching roll540.

As shown inFIG.7, the attaching roll540presses and bonds the magnetic strip300to the laminate from which the resin sheet15has been peeled off. Specifically, the laminate and the magnetic strip300are guided between two rolls disposed to face each other, and the magnetic strip300is pressed against and bonded to the first surface11A of the adhesive layer10using the two rolls as shown inFIG.11.

The magnetic strip300may be disposed such that its center coincides with the center of the adhesive layer10in the width direction, or may be disposed such that its center is away from the center of the adhesive layer10. In this case, the magnetic strip300is arranged to satisfy the conditions of 0 mm<gap a and 0 mm<gap b (seeFIG.12). As shown inFIG.7, the laminate to which the magnetic strip300is bonded is guided from the attaching roll540to the crack roll550.

FIG.12is a cross-sectional view for explaining a state in which the crack21has been formed in the magnetic strip300by the crack roll550.

The crack roll550forms the crack21in the magnetic strip300bonded to the adhesive layer10. Specifically, a laminate to which the magnetic strip300is bonded is guided between two rolls disposed to face each other, and a roll provided with a protrusion among the two rolls is pressed against the magnetic strip300to form the crack21as shown inFIG.12.

Among the two rolls, the roll provided with no protrusion is disposed on the side in which the resin sheet15has been peeled off in the laminate. The magnetic strip300in which the crack21is formed includes a plurality of small pieces22. The plurality of small pieces22are bonded to the adhesive layer10.

Here, the configuration of the crack roll550will be described. The crack roll550is a roll in which a plurality of convex members are arranged on the peripheral surface. The tip of the end of the convex member of the crack roll550may be flat, conical, inverted conical with a recessed center, or cylindrical. The plurality of convex members may be arranged regularly or irregularly.

The long magnetic strip300is pressed against the crack roll550or the long magnetic strip300is caused to pass between the two crack rolls550to continuously form the crack21in the magnetic strip300. Further, the convex member of the crack roll550is pressed against a plurality of places on the surface of the magnetic strip300to form a plurality of cracks21in the magnetic strip300.

In the formation of the crack using the crack roll550, it is preferable to further form a crack connecting the plurality of cracks21in a mesh shape. Specifically, it is preferable to include a step of pressing the crack roll550against the magnetic strip300to form a plurality of cracks21and then forming a crack connecting the plurality of cracks21in a mesh shape.

For example, after an external force is directly applied to the magnetic strip300by using the crack roll550to form the crack21, a second external force may be applied by means such as curving or winding the magnetic strip300to form a crack connecting the plurality of cracks21in a mesh form. A crack connecting the cracks21(a magnetic gap connecting the cracks) is formed with the cracks21as starting points of brittle fracture and/or crack fracture.

In the step of forming a crack connecting the plurality of cracks21in a mesh shape, the second external force as described above may not be applied. When the second external force is not applied, a crack connecting the plurality of cracks21in a mesh shape is formed in the process of forming the plurality of cracks21.

The laminate guided from the crack roll550to the flattening roll560is subjected to a flattening treatment by the flattening roll560. Note that the flattening roll560is also referred to as a shaping roll.

Specifically, the laminate is guided between two rolls disposed opposite to each other in the flattening roll560, and the laminate is sandwiched and pressed by the two rollers. As a result, the surface of the magnetic strip300in which the crack21is formed is flattened.

The laminate subjected to the flattening treatment becomes the magnetic sheet100. The magnetic sheet100is guided to the third winding roll570via the guide roll580. The magnetic sheet100is wound onto a third winding roll570.

The magnetic sheet100may be cut at a desired length instead of being wound by the third winding roll570.

The magnetic sheet100wound by the third winding roll570can be used as the magnetic strip300shown inFIGS.1to6. At this time, the magnetic sheet100can be cut to a desired length and used. Of course, the cut magnetic sheet100may be used instead of the wound magnetic sheet100.

By using the magnetic sheet100as the magnetic strip300shown inFIGS.1to6, the magnetic strips300(magnetic sheets100) to be stacked can be easily bonded to each other. It is easier to handle the magnetic strip300as the magnetic sheet100than to handle the magnetic strip300alone. When a nanocrystalline alloy strip is used as the magnetic strip300, the nanocrystalline alloy strip has a brittle property, and it is not easy to handle the nanocrystalline alloy strip alone.

When the magnetic sheet100of the present disclosure is used as the magnetic strip300inFIGS.1to6, the magnetic gap between the magnetic strips300tends to be larger because a resin layer wider than the magnetic strip300is used. However, the present disclosure has a configuration capable of suppressing a deterioration of characteristics due to the magnetic gap between the magnetic strips300, and even when the magnetic sheet is used as the magnetic strip300inFIGS.1to6, a multilayer magnetic sheet with a high magnetic permeability and a high Q factor can be configured.

According to the multilayer magnetic sheet400with the above configuration, the magnetic gaps in the stacking direction of the magnetic strip300can be suppressed from continuing, and thus a deterioration of the magnetic characteristics in the multilayer magnetic sheet400can be easily prevented. As a result, a multilayer magnetic sheet with a high magnetic permeability and a high Q factor can be obtained.

By setting the width of the multilayer magnetic sheet400to 100 mm or more and 1000 mm or less and the length to 100 mm or more and 1000 mm or less, the multilayer magnetic sheet400can be formed in a desired size.

By making the magnetic strip300an amorphous alloy strip or a nanocrystalline alloy strip, the magnetic strip300can be made a soft magnetic strip. Also, the magnetic strip300can be formed using an alloy.

By including the plurality of small pieces22in the magnetic strip300, the characteristics of the multilayer magnetic sheet400can be easily improved. Specifically, when the multilayer magnetic sheet400is used as a magnetic body for an inductor, the Q factor can be easily improved. When the multilayer magnetic sheet400is used as a magnetic body for magnetic shielding, the eddy current loss can be easily reduced by dividing the current path of the magnetic strip300.

By providing the adhesive layer10on one surface of the magnetic strip300, the adjacent magnetic strip300can be held by the adhesive layer10. Specifically, the adhesive12provided on the first surface11A of the support11is bonded to one of the adjacent magnetic strips300, and the adhesive12provided on the second surface11B is bonded to the other of the adjacent magnetic strips300.

By providing the resin sheet15at the first stacking end401or the second stacking end402, the manufactured multilayer magnetic sheet400can be easily protected. For example, at the time of conveying the manufactured multilayer magnetic sheet400, the adhesive layer10and the magnetic strip300can be easily prevented from being damaged.

An outer layer material selected from an amorphous alloy strip, a nanocrystalline alloy strip, another magnetic material, a metal foil such as aluminum, a resin sheet, or the like may be attached to the first stacking end401or the second stacking end402.

The width A of the region of the adhesive layer10where the adhesive12is provided is larger than the width B of the magnetic strip300. At the time of attaching the magnetic strip300to the adhesive layer10, even when meandering occurs in the adhesive layer10or the magnetic strip300, the adhesive12of the adhesive layer10can be easily disposed on the entire surface of the magnetic strip300.

By setting the value obtained by subtracting the width B from the width A to 0.2 mm or more, a portion where the adhesive12is not disposed on the magnetic strip300can be easily prevented from occurring at the time of attaching the magnetic strip300to the adhesive layer10. By setting the value obtained by subtracting the width B from the width A to 3 mm or less, it is easy to prevent the portion of the magnetic sheet100where the magnetic strip300is not disposed from becoming large.

Note that the technical scope of the present disclosure is not limited to the above embodiment, and various modifications can be made without departing from the gist of the present disclosure. For example, the multilayer magnetic sheet400according to the present disclosure can be used as an inductive element or the like.