Magnetic structures

Abstract

To provide a magnetic structure which is structured to reduce lateral displacement between a magnetic member and an insulation member.SOLUTION: A magnetic structure 10 comprises a magnetic member 20, an internal member 30 and an insulation member 50. A passing hole 28 is formed in the magnetic member 20. The internal member 30 is positioned inside of the passing hole 28. Two recesses 31 are respectively formed in an upper end and a lower end of the internal member 30. The recess 31 in the upper end is recessed so as to be separated from a predetermined surface 26, which is a top face 22 of the magnetic member 20, in a vertical direction (Z direction). The recess 31 in the lower end is recessed so as to be separated from a predetermined surface 26, which is a bottom face 24 of the magnetic member 20, in the vertical direction. The insulation member 50 includes a cover part 56 and a filling part 58. The cover part 56 covers the predetermined surface 26 of the magnetic member 20. The filling part 58 fills the inside of the recess 31. The cover part 56 and the filling part 58 communicate with each other.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a magnetic structure including a magnetic member and an insulating member. [Background technology]

[0002] For example, Patent Document 1 discloses a magnetic structure of this type.

[0003] The magnetic structure disclosed in FIG. 17 of Patent Document 1 includes a substrate having a cavity formed therein, a magnetic member having a through hole formed therein, and an insulating member including an upper prepreg and a lower prepreg. This magnetic structure is manufactured as follows: First, the substrate is mounted on the lower prepreg. Next, the magnetic member is placed inside the cavity of the substrate. Next, resin is filled into the through hole of the magnetic member. Next, the upper prepreg is placed on the magnetic member. The structure assembled in this manner is subjected to a heat press, thereby hardening the resin inside the through hole. Next, via holes are formed through the hardened resin. After that, plating is formed in the via holes. The magnetic structure manufactured as described above can be used as various circuit boards by further processing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-004966 Summary of the Invention [Problem to be solved by the invention]

[0005] The magnetic member and insulating member of the magnetic structure of Patent Document 1 may be displaced laterally due to differences in thermal expansion coefficients when the circuit board generates heat during use. A similar problem occurs when the magnetic member is embedded inside an insulating member made of an insulator such as resin.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a magnetic structure having a structure that can reduce lateral displacement between a magnetic member and an insulating member. [Means for solving the problem]

[0007] The present invention provides a first magnetic structure comprising: A magnetic structure including a magnetic member, an internal member, and an insulating member, a passage hole is formed in the magnetic member, the through hole passes through the magnetic member in the vertical direction, the internal member is located inside the passage hole, a recess is formed in at least one of an upper end and a lower end of the internal member, When the recess is formed at the upper end of the internal member, the recess is recessed so as to be spaced apart in the up-down direction from a predetermined surface that is an upper surface of the magnetic member, When the recess is formed at the lower end of the internal member, the recess is recessed so as to be spaced apart in the up-down direction from a predetermined surface that is a lower surface of the magnetic member, the insulating member has a cover portion and a filling portion, the cover portion covers the predetermined surface of the magnetic member, The filling portion is filled inside the recess, The cover portion and the filling portion are connected to each other. A magnetic structure is provided.

[0008] The present invention provides a first magnetic structure as a second magnetic structure, The recess is formed at each of the upper and lower ends of the internal member. A magnetic structure is provided.

[0009] The present invention provides a third magnetic structure comprising the first or second magnetic structure, the magnetic structure includes a wiring layer and through-hole plating; the insulating member is a prepreg that has been subjected to a thermosetting treatment, the wiring layer is located outside the insulating member in the vertical direction, The through-hole plating penetrates the internal member and the insulating member in the vertical direction and is electrically connected to the wiring layer. A magnetic structure is provided.

[0010] The present invention provides a fourth magnetic structure, which is any one of the first to third magnetic structures, The internal member includes a resin. A magnetic structure is provided.

[0011] The present invention provides a fifth magnetic structure, which is the fourth magnetic structure, The inner member further includes a filler. A magnetic structure is provided.

[0012] The present invention includes, as the first magnetic component, No. 5 A magnetic part used in manufacturing any one of the magnetic structures up to The magnetic component includes a magnetic member and an internal member, a passage hole is formed in the magnetic member, the through hole passes through the magnetic member in the vertical direction, the internal member is located inside the passage hole, a recess is formed in at least one of an upper end and a lower end of the internal member, When the recess is formed at the upper end of the internal member, the recess is recessed so as to be spaced apart in the up-down direction from a predetermined surface that is an upper surface of the magnetic member, When the recess is formed at the lower end of the internal member, the recess is recessed away from a predetermined surface, which is the lower surface of the magnetic member, in the up-down direction. A magnetic component is provided.

[0013] The present invention provides a first magnetic component as the second magnetic component, The recess is formed at each of the upper and lower ends of the internal member. A magnetic component is provided. [Effects of the Invention]

[0014] The insulating member of the present invention covers a predetermined surface of the magnetic member and fills a recess that is recessed away from the predetermined surface in the vertical direction. The insulating member filled in the recess functions as an anchor that prevents lateral displacement between the magnetic member and the insulating member. In other words, the present invention can provide a magnetic structure that has a structure that can reduce lateral displacement between the magnetic member and the insulating member. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a top view of a magnetic component according to an embodiment of the present invention, the magnetic component being disposed on a release sheet; [Figure 2] 2 is a cross-sectional view showing the magnetic component and the release sheet of FIG. 1 taken along line II-II. [Figure 3] 3 is a cross-sectional view schematically showing the structure of a passage hole of the magnetic component of FIG. 2. [Figure 4] FIG. 2 is an exploded perspective view showing a magnetic structure including the magnetic component of FIG. 1. [Figure 5] 5 is a cross-sectional view schematically illustrating the structure of the magnetic structure of Fig. 4. The cross section shown corresponds to the cross section of Fig. 3. [Figure 6] 6 is a cross-sectional view schematically showing the structure of the magnetic structure of Fig. 5. The magnetic structure has been subjected to heat pressing. [Figure 7] 7 is a cross-sectional view schematically showing the structure of the magnetic structure of Fig. 6. A through-hole is formed in the magnetic structure. [Figure 8] 8 is a cross-sectional view schematically showing the structure of the magnetic structure of Fig. 7. Plating is formed on the magnetic structure. [Figure 9] 9 is a top view showing an example of a circuit board manufactured using the magnetic structure of FIG. 8, with hidden parts drawn with dashed lines. [Figure 10]5 is a perspective view showing a modified example of the magnetic structure of FIG. 4. The magnetic component is embedded inside an insulating body made of resin. DETAILED DESCRIPTION OF THE INVENTION

[0016] 1 and 2, a magnetic component 12 according to an embodiment of the present invention includes a magnetic member 20 made of a soft magnetic material and four internal members 30 made of an insulating material.

[0017] The magnetic member 20 of this embodiment has a thin, flat plate shape in the vertical direction, and extends along a horizontal plane (XY plane) perpendicular to the vertical direction. The vertical direction in this embodiment is the Z direction. In this embodiment, "upper" refers to the +Z direction, and "lower" refers to the -Z direction. However, terms indicating positional relationships such as "horizontal," "upper," and "lower" in the following description do not indicate absolute positional relationships with respect to the ground, but merely indicate relative positional relationships in the drawings.

[0018] The magnetic member 20 of this embodiment contains flat-shaped soft magnetic metal powder and inclusions. The inclusions are mainly composed of an inorganic oxide such as silicon oxide (SiO2) and bind the soft magnetic metal powder. The soft magnetic metal powder extends generally parallel to a horizontal plane.

[0019] The magnetic member 20 can be produced, for example, as follows. First, a flat-shaped soft magnetic metal powder is mixed with a solvent, a thickener, and a binder to produce a slurry. Next, the slurry is applied to a substrate such as a PET (polyethylene terephthalate) film. Next, the applied slurry is heated to volatilize the solvent, thereby producing a sheet-like preform. Next, the preform is punched out into the required shape. The required number of punched sheets are stacked one on top of the other and pressed together to produce a flat-plate-like compact. The compact is then machined using a machine tool such as a milling machine, thereby producing the magnetic member 20 in the required shape.

[0020] As described above, the magnetic member 20 of this embodiment has a rectangular shape in the horizontal plane. That is, the magnetic member 20 is a rectangular flat plate. However, the present invention is not limited to this, and the shape of the magnetic member 20 can be modified in various ways as needed. For example, the magnetic member 20 may have a disk shape. Furthermore, the material and manufacturing method of the magnetic member 20 are not particularly limited as long as the magnetic member 20 can be processed, such as by drilling holes.

[0021] The magnetic member 20 of this embodiment has an upper surface 22 and a lower surface 24, which are both surfaces in the vertical direction. Each of the upper surface 22 and the lower surface 24 of this embodiment is a flat surface without any irregularities and extends parallel to a horizontal plane. However, the present invention is not limited to this. For example, each of the upper surface 22 and the lower surface 24 may have small irregularities formed thereon.

[0022] The magnetic member 20 of this embodiment has four through holes 28 formed therein. The four through holes 28 are located near the four corners of the magnetic member 20, respectively. Each of the through holes 28 has a circular shape in the horizontal plane and penetrates the magnetic member 20 in the vertical direction. The magnetic member 20 of this embodiment has two or more through holes 28 arranged as described above. However, the present invention is not limited to this. For example, the number of through holes 28 may be one, or may be formed in the middle of the magnetic member 20 in the horizontal plane. The shape of each of the through holes 28 in the horizontal plane is not particularly limited. Furthermore, each of the through holes 28 may penetrate the magnetic member 20 straight in the vertical direction, or may penetrate the magnetic member 20 in a direction oblique to the vertical direction.

[0023] The four internal members 30 are provided corresponding to the respective passage holes 28. Therefore, when the number of passage holes 28 is 1, the number of internal members 30 is 1. Each of the internal members 30 is located inside the corresponding passage hole 28.

[0024] The internal member 30 can be formed, for example, as follows. First, the magnetic member 20 is placed on a release sheet 80. A thin film such as a PET film or a Teflon (registered trademark) film can be used as the release sheet 80. Next, a slurry containing a thermosetting material and a solvent is prepared. A thermosetting resin such as an epoxy resin can be used as the thermosetting material. Alternatively, an inorganic filler such as silicon oxide can be added to the epoxy resin to be used as the thermosetting material.

[0025] Next, the slurry is filled into the passage holes 28 using a method such as dispensing or squeegeeing. The magnetic member 20 is then heat-treated to harden the slurry inside the passage holes 28. Specifically, when the magnetic member 20 is heat-treated, the solvent in the slurry volatilizes and the thermosetting material shrinks in volume, thereby forming the internal member 30. As the thermosetting material shrinks in volume, it adheres to the inner walls of the passage holes 28 due to surface tension. As a result, the upper and lower end surfaces of the internal member 30 have concave shapes that are recessed toward each other. As will be described later, the concave portions of the internal member 30 are used to reduce lateral slippage of layers made of materials such as prepreg when they are arranged above and below the magnetic component 12.

[0026] When forming the internal member 30, if the viscosity of the slurry is too low, it is difficult to form a concave portion on the lower end surface of the internal member 30. On the other hand, if the viscosity of the slurry is too high, the flow of the slurry is suppressed, making it difficult for the thermosetting material to adhere to the inner wall of the passage hole 28. In addition, voids (air gaps) are likely to form inside the internal member 30. To prevent the above-mentioned problems, the viscosity of the slurry is preferably in a predetermined range of 100 mPa to 100,000 mPa. For example, the viscosity of the slurry can be adjusted to the predetermined range by adjusting the amount of filler and the amount of solvent added to the epoxy resin. Furthermore, by adding a filler, the thermal expansion coefficient of the internal member 30 can be made closer to that of the magnetic member 20, thereby preventing cracks in the internal member 30 during heat treatment.

[0027] To more reliably form recessed portions on both the upper and lower end surfaces of the internal member 30, for example, the magnetic member 20 may be heat-treated while being rotated around a predetermined central axis. This central axis may extend parallel to the up-down direction and pass through the middle of the horizontal surface of the magnetic member 20. More specifically, the magnetic member 20 may be barrel-polished while being heat-treated. By rotating the magnetic member 20 during the heat treatment, the slurry can be pressed against the inner walls of the through holes 28. Even when forming recessed portions in this manner, the viscosity of the slurry is preferably within a predetermined range of 100 mP to 100,000 mP.

[0028] One of the internal members 30 formed as described above will now be described in more detail. The following description is applicable to each of the internal members 30.

[0029] 3, according to this embodiment, two recesses 31 (recessed portions) including an upper recess 32 and a lower recess 34 are formed in the internal member 30. The upper recess 32 is formed at the upper end of the internal member 30, and the lower recess 34 is formed at the lower end of the internal member 30. That is, according to this embodiment, the recesses 31 are formed at both the upper and lower ends of the internal member 30.

[0030] According to the above-described structure, lateral displacement can be reduced both above and below. However, the present invention is not limited to this. For example, the recess 31 (upper recess 32) may be formed only at the upper end of the internal member 30, and the lower end surface of the internal member 30 may be a plane parallel to the horizontal plane. On the other hand, the recess 31 (lower recess 34) may be formed only at the lower end of the internal member 30, and the upper end surface of the internal member 30 may be a plane parallel to the horizontal plane. In other words, it is sufficient that the recess 31 is formed at at least one of the upper end and lower end of the internal member 30.

[0031] The recess 31 (upper recess 32) formed at the upper end of the internal member 30 is recessed so as to be separated in the vertical direction from the predetermined surface 26, which is the upper surface 22 of the magnetic member 20. In other words, when the recess 31 is formed at the upper end of the internal member 30, the recess 31 is recessed so as to be separated in the vertical direction from the predetermined surface 26, which is the upper surface 22 of the magnetic member 20. The recess 31 (lower recess 34) formed at the lower end of the internal member 30 is recessed so as to be separated in the vertical direction from the predetermined surface 26, which is the lower surface 24 of the magnetic member 20. In other words, when the recess 31 is formed at the lower end of the internal member 30, the recess 31 is recessed so as to be separated in the vertical direction from the predetermined surface 26, which is the lower surface 24 of the magnetic member 20.

[0032] More specifically, the periphery of the upper recess 32 in the horizontal plane is at the same position as the predetermined surface 26 (upper surface 22) in the vertical direction, and the center of the upper recess 32 in the horizontal plane is recessed downward. The periphery of the lower recess 34 in the horizontal plane is at the same position as the predetermined surface 26 (lower surface 24) in the vertical direction, and the center of the lower recess 34 in the horizontal plane is recessed upward.

[0033] In order to more reliably reduce lateral slippage, it is preferable that the upper recess 32 be deeply recessed downward, and the lower recess 34 be deeply recessed upward. However, the present invention is not limited to this. For example, the depth of each of the upper recess 32 and the lower recess 34 may be as needed. Furthermore, the peripheral edge of the upper recess 32 in the horizontal plane may be located below the predetermined surface 26 (upper surface 22) in the vertical direction, and the peripheral edge of the lower recess 34 in the horizontal plane may be located above the predetermined surface 26 (lower surface 24) in the vertical direction.

[0034] In each of the upper recess 32 and the lower recess 34 of this embodiment, a cross section (vertical cross section) taken along a vertical plane including the center of the recess has a lens shape. The upper recess 32 and the lower recess 34 have vertically symmetrical shapes. However, the present invention is not limited to this. For example, the shapes of the vertical cross sections of the upper recess 32 and the lower recess 34 are not particularly limited. The upper recess 32 and the lower recess 34 may have vertically asymmetrical shapes.

[0035] 4, the magnetic member 20 is used when manufacturing the magnetic structure 10. A method for manufacturing the magnetic structure 10 of this embodiment will be described below.

[0036] First, in addition to the magnetic component 12, the magnetic structure 10 is provided with a substrate 40 and two insulating members 50, including an upper insulating member 52 and a lower insulating member 54. The substrate 40 in this embodiment is an FR4 (Flame Retardant Type 4) substrate. Each insulating member 50 in this embodiment is a prepreg with a thickness of approximately 0.1 mm. The prepreg in this embodiment is formed from carbon fiber impregnated with epoxy resin before heat curing. A wiring layer 60 is formed on each insulating member 50. Each wiring layer 60 in this embodiment is a conductive sheet made of copper foil with a thickness of approximately 0.035 mm. The wiring layer 60 includes an upper wiring layer 62 and a lower wiring layer 64. The upper wiring layer 62 is formed on the upper surface of the upper insulating member 52. The lower wiring layer 64 is formed on the lower surface of the lower insulating member 54.

[0037] A cavity 48 is formed in the substrate 40. The cavity 48 in this embodiment is a rectangular hole formed in the substrate 40. The cavity 48 is located in the middle of the substrate 40 in the horizontal plane and penetrates the substrate 40 in the vertical direction. The cavity 48 has substantially the same size as the magnetic member 20.

[0038] Each member of this embodiment has the structure described above. However, the present invention is not limited to this. For example, the substrate 40 is not limited to an FR4 substrate. Furthermore, the wiring layer 60 may be formed as needed.

[0039] 4 and 5, after the above-mentioned components are prepared, the magnetic component 20 is fitted into the cavity 48. Next, the substrate 40 and two insulating components 50 are stacked one above the other. Specifically, the substrate 40 is placed on the lower insulating component 54, and the upper insulating component 52 is placed on the substrate 40. As a result, the magnetic structure 10 shown in FIG. 5 is formed.

[0040] 5 and 6, next, the magnetic structure 10 of FIG. 5 is heat-pressed in a vacuum to integrate the substrate 40 (see FIG. 4) and the two insulating members 50. More specifically, the magnetic structure 10 of FIG. 5 is sandwiched between two members and pressurized in a vacuum, while being heated to a temperature sufficient to melt the epoxy resin of the insulating members 50. For example, the magnetic structure 10 of FIG. 5 is held at a temperature of 175° C. for one hour.

[0041] During the heat press, epoxy resin seeps out from the insulating member 50 and covers the upper and lower surfaces of the substrate 40 (see FIG. 4 ), adhering to the substrate 40 and the magnetic member 20. More specifically, some of the epoxy resin that has seeped out from the insulating member 50 adheres to the entire upper surface 22 and lower surface 24 of the magnetic member 20. In addition, the epoxy resin that has seeped out from the insulating member 50 flows into the upper recess 32 and the lower recess 34, filling them almost completely. That is, some of the insulating member 50 is filled in the upper recess 32 and the lower recess 34.

[0042] 6 and 7, after the epoxy resin seeping out from the insulating member 50 has hardened, a through hole 18 is formed in the magnetic structure 10 of FIG. 6. The through hole 18 is formed to penetrate the internal member 30 and the insulating member 50 in the vertical direction. Furthermore, the through hole 18 is formed to pass through the center of the internal member 30, sufficiently separated from the inner wall surface of the through hole 28 in the horizontal plane. In this embodiment, the diameter of the through hole 18 in the horizontal plane is 0.2 mm or more. However, the size of the through hole 18 in the present invention is not particularly limited.

[0043] 7 and 8, next, plating 70 is formed on the magnetic structure 10 of FIG. 7. Specifically, upper plating 72 is formed on the upper surface of the upper wiring layer 62, and lower plating 74 is formed on the lower surface of the lower wiring layer 64. In addition, through-hole plating 78 is formed on the entire inner wall surface of the through-hole 18, and the upper plating 72 and the lower plating 74 are connected to each other by the through-hole plating 78. In this embodiment, plating 70 is a single-layer copper plating having a thickness of 20 μm or more. However, the present invention is not limited to this. For example, plating 70 may have a base plating layer made of a highly corrosion-resistant metal such as Ni, or a top plating layer made of a metal that is difficult to oxidize such as Au or Ag. The thickness of plating 70 is not particularly limited.

[0044] Through the above steps, the magnetic structure 10 of this embodiment can be fabricated.

[0045] The fabricated magnetic structure 10 includes a magnetic member 20, an internal member 30, and an insulating member 50. A through hole 28 is formed in the magnetic member 20. The through hole 28 passes through the magnetic member 20 in the vertical direction. The internal member 30 is located inside the through hole 28.

[0046] A recess 31 is formed in at least one of the upper and lower ends of the internal member 30. The recess 31 formed in the upper end of the internal member 30 is recessed so as to be separated in the up-down direction from the predetermined surface 26, which is the upper surface 22 of the magnetic member 20. In other words, when the recess 31 is formed in the upper end of the internal member 30, the recess 31 is recessed so as to be separated in the up-down direction from the predetermined surface 26, which is the upper surface 22 of the magnetic member 20. The recess 31 formed in the lower end of the internal member 30 is recessed so as to be separated in the up-down direction from the predetermined surface 26, which is the lower surface 24 of the magnetic member 20. In other words, when the recess 31 is formed in the lower end of the internal member 30, the recess 31 is recessed so as to be separated in the up-down direction from the predetermined surface 26, which is the lower surface 24 of the magnetic member 20.

[0047] The insulating member 50 has a cover portion 56 and a filling portion 58. The cover portion 56 and the filling portion 58 are made of epoxy resin that seeps out of the insulating member 50 and then hardens. The cover portion 56 covers the predetermined surface 26 of the magnetic member 20. The filling portion 58 fills the interior of the recess 31. In each insulating member 50, the cover portion 56 and the filling portion 58 are connected to each other.

[0048] 8 and 9, a desired conductor pattern can be formed by etching the upper plating 72 and the lower plating 74 of the magnetic structure 10 in Fig. 8 together with the upper wiring layer 62 and the lower wiring layer 64. Referring to Fig. 9, as a result of the etching, a circuit board 11 having, for example, a coil is formed. In other words, the circuit board 11 is the magnetic structure 10 that has been processed by etching or the like.

[0049] Referring to FIG. 9, the circuit board 11 (magnetic structure 10) has only a simple coil. However, the present invention is not limited to this. For example, the circuit board 11 may have circuits other than the coil, or may further have electronic components (not shown) attached. Furthermore, the method of forming the conductor pattern is not limited to etching. After etching, unnecessary portions of the magnetic structure 10 may be cut off.

[0050] 8 and 9, according to the prior art, a circuit board is fabricated using a magnetic member 20 without an internal member 30, as will be described later. However, the circuit board fabricated in this manner may be further subjected to a reflow process. Furthermore, the circuit board may generate heat during use. As a result, the magnetic member 20 and the insulating member 50 of the circuit board may shift laterally relative to each other due to differences in their thermal expansion coefficients.

[0051] On the other hand, the insulating member 50 of this embodiment covers the predetermined surface 26 of the magnetic member 20 and fills the interior of a recess 31 that is recessed so as to be spaced apart from the predetermined surface 26 in the vertical direction. The insulating member 50 filled inside the recess 31 functions as an anchor that prevents lateral displacement between the magnetic member 20 and the insulating member 50. In other words, the present invention can provide a magnetic structure 10 that has a structure that can reduce lateral displacement between the magnetic member 20 and the insulating member 50.

[0052] According to the prior art, the upper surface 22 and the lower surface 24 of the magnetic member 20 are formed roughly, thereby allowing the upper surface 22 and the lower surface 24 to function as anchors. Specifically, the anchor effect is achieved by engaging the cover portion 56 of the insulating member 50 with the fine irregularities formed on the upper surface 22 and the lower surface 24. On the other hand, according to the present embodiment, the recess 31 is formed in a portion having a large horizontal cross section, such as the through hole 28, so that a large volume of the filling portion 58 is filled in the through hole 28. As a result, a higher anchor effect can be achieved than in the prior art. However, the present invention is not limited to this. For example, the anchor effect may be achieved by the fine irregularities on the upper surface 22 and the lower surface 24 in addition to the recess 31.

[0053] The recess 31 in this embodiment is a part of the passage hole 28 provided for forming the through hole 18. That is, a part of the passage hole 28, which is a portion necessary for manufacturing the circuit board 11, functions as an anchor. Therefore, a high anchor effect can be obtained without causing problems such as deterioration of magnetic properties.

[0054] In this embodiment, the recess 31 surrounds the through-hole plating 78 on the horizontal surface. The through-hole plating 78 is a thin portion that electrically connects the upper wiring layer 62 and the lower wiring layer 64, and extends in the vertical direction. If lateral displacement occurs in the portion where the through-hole plating 78 is formed, the through-hole plating 78 can easily be damaged, which could deteriorate the electrical connection between the upper wiring layer 62 and the lower wiring layer 64. On the other hand, according to this embodiment, lateral displacement of the portion where the through-hole plating 78 is formed is minimized, so that the electrical connection between the upper wiring layer 62 and the lower wiring layer 64 can be reliably maintained.

[0055] According to this embodiment, the insulating member 50 includes an upper insulating member 52 that covers the upper surface 22 of the magnetic member 20, and a lower insulating member 54 that covers the lower surface 24 of the magnetic member 20. However, the present invention is not limited to this. In order to obtain the anchor effect of the present invention, the insulating member 50 may include only one of the upper insulating member 52 and the lower insulating member 54.

[0056] According to the magnetic structure 10 of this embodiment, recesses 31 are formed at both the upper and lower ends of the internal member 30. This structure can reduce lateral displacement between the upper surface 22 of the magnetic member 20 and the upper insulating member 52, and can also reduce lateral displacement between the lower surface 24 of the magnetic member 20 and the lower insulating member 54. However, the present invention is not limited to this. For example, if the insulating member 50 includes only the upper insulating member 52, there is no need to form the lower recess 34. Also, if the insulating member 50 includes only the lower insulating member 54, there is no need to form the upper recess 32.

[0057] As described above, the magnetic structure 10 of FIG. 8 can be used as a circuit board 11 by etching it. More specifically, the magnetic structure 10 of FIG. 8 includes a wiring layer 60 and through-hole plating 78. The insulating member 50 is a prepreg that has been subjected to a thermosetting treatment. The wiring layer 60 is located outside the insulating member 50 in the vertical direction. The through-hole plating 78 penetrates the internal member 30 and the insulating member 50 in the vertical direction and is electrically connected to the wiring layer 60.

[0058] However, the magnetic structure 10 of the present invention is not limited to the magnetic structure 10 of FIG. 8, and may have the structure of each of the magnetic structures 10 of FIGS. 5 to 7. For example, referring to FIG. 6 together with FIG. 7, the magnetic structure 10 before the through-holes 18 are formed is also the magnetic structure 10 of the present invention. That is, the magnetic structure 10 only needs to include through-hole plating 78 as needed. Furthermore, the magnetic structure 10 only needs to include a wiring layer 60 as needed. In other words, the magnetic structure 10 may include only the magnetic member 20, the internal member 30, and the insulating member 50.

[0059] As described above, the internal member 30 of this embodiment is primarily made of hardened epoxy resin. That is, the internal member 30 contains resin. Such an internal member 30 can be filled into the through hole 28 even if the size of the through hole 28 in the horizontal plane is small. In addition, by forming the through hole 18 so that it passes through the center of the internal member 30 in the horizontal plane, it is possible to reliably insulate the through-hole plating 78 from the magnetic member 20. As a result, for example, corrosion of the surface of the magnetic member 20 due to contact with the through-hole plating 78 can be prevented.

[0060] The internal member 30 of this embodiment further contains a filler. As described above, by adding a filler to the resin, the thermal expansion coefficient of the internal member 30 can be made closer to that of the magnetic member 20. Therefore, even if the magnetic structure 10 generates heat during use, cracks in the internal member 30 can be prevented.

[0061] The internal member 30 of this embodiment is made of epoxy resin or filler. However, the present invention is not limited to this. For example, if the size of the passing hole 28 in the horizontal plane is sufficiently large, a small FR4 member may be fitted into the passing hole 28 to form the internal member 30. In this case, the recess 31 can be formed by making the vertical size of the FR4 member smaller than the vertical size of the passing hole 28.

[0062] 1 to 9, a conventional manufacturer of circuit boards (hereinafter referred to as "board manufacturer") fabricates circuit boards, for example, as follows. The board manufacturer first obtains from a component manufacturer a magnetic member 20 that has the necessary through holes 28 formed therein but does not have an internal member 30. The board manufacturer then fits the magnetic member 20 into the cavity 48 of the board 40 and places the board 40 on the lower insulating member 54. The board manufacturer then places the upper insulating member 52 on the board 40 and performs a heat press. During this heat press, the epoxy resin contained in the insulating member 50 is squeezed out and fills the through holes 28. The subsequent steps are the same as those of the present embodiment described above.

[0063] According to the above-described manufacturing method, it is difficult to squeeze out an appropriate amount of epoxy resin to fill the passage holes 28. In addition, due to the difference in thermal expansion coefficient between the epoxy resin filling the passage holes 28 and the magnetic member 20, cracks may occur in the epoxy resin hardened inside the passage holes 28.

[0064] One possible solution to the above problem is to fill the through-holes 28 of the magnetic member 20 with a filler having a thermal expansion coefficient similar to that of the magnetic member 20 after placing the substrate 40 on the lower insulating member 54. More specifically, the filler can be prepared by incorporating a filler into an epoxy resin. However, in this case, the clear recesses 31 as in the present embodiment are not formed, which may result in an insufficient anchoring effect. In addition, this manufacturing method requires the use of a fluid, difficult-to-handle filler only during the intermediate steps of the circuit board manufacturing process. For example, the amount of filler filled into the through-holes 28 must be carefully controlled. Furthermore, post-processing, such as scraping off any filler that protrudes from the through-holes 28, may be required.

[0065] On the other hand, according to this embodiment, the anchoring effect can be reliably obtained by the clear recesses 31. In addition, the process of filling with a filler at the board manufacturer can be omitted. In other words, the board manufacturer basically only needs to carry out dry processes, which simplifies the manufacturing process at the board manufacturer.

[0066] As can be understood from the above description, the internal member 30 of the magnetic component 12 only needs to be hardened to the extent that it maintains its shape during transportation to the board manufacturer. In other words, the internal member 30 of the magnetic component 12 may be semi-hardened.

[0067] In addition to the various modifications already described, this embodiment can be further modified in various ways.

[0068] For example, referring to FIG. 10 together with FIGS. 1 and 3, a magnetic structure 10A according to a modified example includes the same magnetic component 12 as the magnetic structure 10 and an insulating member 14A that is not included in the magnetic structure 10. The magnetic structure 10A of the modified example includes only the magnetic component 12 and the insulating member 14A. The magnetic component 12 is embedded inside the insulating member 14A when the insulating member 14A is molded. The magnetic structure 10A of the modified example can be used as a component for various electronic devices. In the magnetic structure 10A, a recess 31 is also formed in at least one of the upper and lower ends of the internal member 30. During the molding process of the insulating member 14A, a portion of the insulating member 14A fills at least one of the recesses 31, thereby reducing lateral displacement between the magnetic component 12 and the insulating member 14A. [Explanation of symbols]

[0069] 10,10A magnetic structure 11 Circuit Board 12 Magnetic parts 14A Insulating material 18 through holes 20 Magnetic components 22 Top side 24 Bottom side 26 Specified surface 28 Passing hole 30 Internal parts 31 Recess 32 Upper recess 34 Lower recess 40 boards 48 Cavity 50 Insulating material 52 Upper insulating member 54 Lower insulating member 56 Cover part 58 Filling section 60 wiring layer 62 Upper wiring layer 64 Lower wiring layer 70 Plating 72 Upper plating 74 Underside plating 78 Through-hole plating 80 Release Sheet

Claims

1. A magnetic structure including a magnetic member, an internal member, and an insulating member, a passage hole is formed in the magnetic member, the through hole passes through the magnetic member in the vertical direction, the internal member is located inside the passage hole, a recess is formed in at least one of an upper end and a lower end of the internal member, When the recess is formed at the upper end of the internal member, the recess is recessed so as to be spaced apart in the up-down direction from a predetermined surface that is an upper surface of the magnetic member, When the recess is formed at the lower end of the internal member, the recess is recessed so as to be spaced apart in the up-down direction from a predetermined surface that is a lower surface of the magnetic member, the insulating member has a cover portion and a filling portion, the cover portion covers the predetermined surface of the magnetic member, The filling portion is filled inside the recess, The cover portion and the filling portion are connected to each other. magnetic structure.

2. 10. The magnetic structure of claim 1, The recess is formed at each of the upper and lower ends of the internal member. magnetic structure.

3. 3. The magnetic structure according to claim 1 or 2, the magnetic structure includes a wiring layer and through-hole plating; the insulating member is a prepreg that has been subjected to a thermosetting treatment, the wiring layer is located outside the insulating member in the vertical direction, The through-hole plating penetrates the internal member and the insulating member in the vertical direction and is electrically connected to the wiring layer. magnetic structure.

4. A magnetic structure according to any one of claims 1 to 3, The internal member includes a resin. magnetic structure.

5. 5. The magnetic structure of claim 4, The inner member further includes a filler. magnetic structure.

6. A magnetic component used in manufacturing the magnetic structure according to any one of claims 1 to 5, The magnetic component includes a magnetic member and an internal member, a passage hole is formed in the magnetic member, the through hole passes through the magnetic member in the vertical direction, the internal member is located inside the passage hole, a recess is formed in at least one of an upper end and a lower end of the internal member, When the recess is formed at the upper end of the internal member, the recess is recessed so as to be spaced apart in the up-down direction from a predetermined surface that is an upper surface of the magnetic member, When the recess is formed at the lower end of the internal member, the recess is recessed away from a predetermined surface, which is the lower surface of the magnetic member, in the up-down direction. Magnetic parts.

7. 7. The magnetic component according to claim 6, The recess is formed at each of the upper and lower ends of the internal member. Magnetic parts.

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