Inductor

The inductor design with intersecting magnetic core surfaces and convex portions addresses the challenge of suppressing whirlpool currents by attenuating current density, effectively reducing vortex current generation in thin magnetic core inductors.

WO2025022712A1PCT designated stage expired Publication Date: 2025-01-30ADVANTEST CORP
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Patent Information

Application Number
PCT/JP2024/009972
Authority / Receiving Office
WO · WO
Patent Type
Applications
Current Assignee / Owner
Priority Date
2023-07-26
Filing Date
2024-03-14
Publication Date
2025-01-30

AI Technical Summary

Technical Problem

Existing inductors with thin magnetic cores face challenges in suppressing whirlpool currents, particularly in flat circuit designs, where molding the magnetic core is difficult and effective suppression of vortex currents is hard to achieve.

Method used

The inductor design features a magnetic core with intersecting end surfaces and a coil wrapped around it, incorporating multiple convex portions with spacings smaller than the electromagnetic wave wavelength and depths that attenuate current density to a specific ratio, hindering electron movement and reducing whirlpool currents.

Benefits of technology

This configuration effectively suppresses whirlpool currents by hindering electron movement on the magnetic core's end surfaces, reducing current density and minimizing vortex current generation.

✦ Generated by Eureka AI based on patent content.

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Abstract

The inductor comprises a magnetic core and a coil. The magnetic core has an end surface and a side surface that intersects the end surface, and is formed on a substrate. The coil is wound around the side surface. The end surface has a plurality of protrusions. An interval between the protrusions is smaller than the wavelength of an electromagnetic wave that is generated by an eddy current that occurs in the end surface. The depth of the protrusions is deeper than a predetermined depth at which the electric current density of the eddy current is attenuated to a predetermined ratio.
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Description

inductor

[0001] The present invention relates to a magnetic core for an inductor.

[0002] 2. Description of the Related Art Conventionally, inductors in which a coil is wound around a thin magnetic core have been known (see, for example, Patent Documents 1 to 3).

[0003] Japanese Patent Laid-Open No. 7-249516 Japanese Patent Laid-Open No. 2020-155733 Japanese Patent Laid-Open No. 2013-258393

[0004] However, with the above-described conventional techniques, eddy currents occur in the magnetic core. While eddy currents can be suppressed if the magnetic core can be powder-molded, it is difficult to powder-molde a thin magnetic core (especially one that can be considered a planar circuit).

[0005] Therefore, an object of the present invention is to suppress the eddy current generated in the magnetic core of an inductor.

[0006] The inductor of the present invention has an end face and a side face intersecting the end face, and comprises a magnetic core formed on a substrate and a coil wound around the side face, the end face having a plurality of protrusions, the spacing between the protrusions being smaller than the wavelength of the electromagnetic waves generated by eddy currents generated at the end face, and the depth of the protrusions being greater than a predetermined depth at which the current density of the eddy currents attenuates to a predetermined rate.

[0007] In the inductor configured as described above, the magnetic core has an end face and a side face intersecting the end face, and is formed on a substrate. A coil is wound around the side face. The end face has a plurality of protrusions. The spacing between the protrusions is smaller than the wavelength of the electromagnetic waves generated by eddy currents generated on the end face. The depth of the protrusions is greater than a predetermined depth at which the current density of the eddy currents attenuates to a predetermined rate.

[0008] In the inductor according to the present invention, the predetermined depth may be a depth at which the current density of the eddy current is 1 / e of the current density at the end surface (where e is the base of the natural logarithm).

[0009] In the inductor according to the present invention, the interval may be constant.

[0010] In the inductor according to the present invention, the spacing may take different values.

[0011] In the inductor according to the present invention, the width of the protrusion may be narrowed toward the tip of the protrusion.

[0012] In the inductor according to the present invention, the width of the protrusion may be constant.

[0013] In addition, the inductor according to the present invention may include an inductor in which the width of the convex portion narrows as it approaches the tip of the convex portion, and an inductor in which the width of the convex portion is constant.

[0014] In the inductor according to the present invention, the protrusions may be arranged spaced apart in the width direction of the magnetic core.

[0015] In the inductor according to the present invention, the protrusions may be arranged spaced apart in the thickness direction of the magnetic core.

[0016] In the inductor according to the present invention, the magnetic core may be made of any one of permendur, FeNi, silicon steel, Ni, and CoFeSiB nanocrystalline material.

[0017] In the inductor according to the present invention, the magnetic core may be formed by sputtering.

[0018] In the inductor according to the present invention, the magnetic core may be plated.

[0019] 7(a) and 7(b) are a left side view and a front view, respectively, of an inductor 1 according to a modified example of the first embodiment of the present invention; FIG. 7(a) is a plan view of an inductor 1 according to a first embodiment of the present invention; FIG. 7(b) is a cross-sectional view taken along the line II-II of FIG. 1; FIG. 7(b) is a left side view and a front view, respectively, of an inductor 1 according to a modified example of the first embodiment; FIG. 8(a) is a left side view and a front view, respectively, of an inductor 1 according to a modified example of the second embodiment; FIG. 9(a) is a partial enlarged view of a convex portion 4a1 when the spacing is a constant value d in the first embodiment; and FIG. 9(b) is a partial enlarged view of a convex portion 4a1 when the spacing is different values ​​d1 and d2 in the first embodiment. FIG. 10( a) is a partial enlarged view of the convex portion 4a1 when the spacing is a constant value d in the second embodiment, and FIG. 10( b) is a partial enlarged view of the convex portion 4a1 when the spacing is different values ​​d1 and d2.

[0020] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0021] First Embodiment Fig. 1 is a plan view of an inductor 1 according to a first embodiment of the present invention. Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1. Fig. 3 is a left side view of the inductor 1 according to the first embodiment. However, the coil 6 is not shown in Fig. 3.

[0022] The inductor 1 according to the first embodiment includes a magnetic core 4 and a coil 6 .

[0023] The magnetic core 4 is formed on the substrate 2. For example, the magnetic core 4 is formed on the substrate 2 by sputtering (thickness: 1 to 3 μm) or plating (thickness: 5 to 10 μm). The material of the magnetic core 4 is, for example, any one of permendur, FeNi, silicon steel, Ni, and CoFeSiB nanocrystalline material.

[0024] The magnetic core 4 has end faces 4E1 and 4E2 and side faces 4S1 to 4S4 (see FIG. 2) that intersect with the end faces 4E1 and 4E2. In FIG. 1, the end face 4E1 is at the left end of the magnetic core 4, and the end face 4E2 is at the right end of the magnetic core 4.

[0025] In FIG. 2, side surface 4S1 is the surface on the top of magnetic core 4, side surface 4S2 is the surface on the bottom of magnetic core 4, side surface 4S3 is the surface on the right side of magnetic core 4, and side surface 4S4 is the surface on the left side of magnetic core 4.

[0026] Coil 6 is wound around side surfaces 4S1 to 4S4. When a current flows through coil 6, eddy currents are generated on end surfaces 4E1 and 4E2.

[0027] The end face 4E1 has a plurality of protrusions 4a1, and the end face 4E2 has a plurality of protrusions 4a2.

[0028] The interval d between the protrusions 4a1 is smaller than the wavelength of the electromagnetic wave generated by the eddy current generated on the end face 4E1. The interval d between the protrusions 4a2 is smaller than the wavelength of the electromagnetic wave generated by the eddy current generated on the end face 4E2. For example, the interval d is 100 to 900 μm. Furthermore, the interval d is constant.

[0029] However, the interval may not be a constant value d but may be a different value. Fig. 9A is a partial enlarged view of the convex portion 4a1 in the first embodiment when the interval is a constant value d, and Fig. 9B is a partial enlarged view of the convex portion 4a1 in the first embodiment when the interval is different values ​​d1 and d2.

[0030] The case where the interval takes a constant value d (FIG. 9(a)) corresponds to FIG. 1, but it is also possible for the interval to take different values ​​d1 and d2 (FIG. 9(b)). Of course, it is also possible for the interval to take three or more values.

[0031] The depth D of the protrusion 4a1 is deeper than the predetermined depth at which the current density of the eddy current attenuates to a predetermined rate. The depth D of the protrusion 4a2 is deeper than the predetermined depth at which the current density of the eddy current attenuates to a predetermined rate. The predetermined depth may be set to a value that makes the current density of the eddy current sufficiently small. For example, the predetermined depth is a depth at which the current density of the eddy current is 1 / e of the current density at the end surface 4E1 and the end surface 4E2 (where e is the base of the natural logarithm).

[0032] The width W of the protrusions 4a1 and 4a2 narrows toward the tips of the protrusions 4a1 and 4a2. The protrusions 4a1 and 4a2 are spaced apart in the width direction of the magnetic core 4.

[0033] Next, the operation of the first embodiment will be described.

[0034] If convex portions 4a1 and 4a2 were not provided, when a current is passed through coil 6, electrons would move on end faces 4E1 and 4E2 of magnetic core 4, generating eddy currents. However, in reality, because convex portions 4a1 and 4a2 are provided, even if electrons try to move on end faces 4E1 and 4E2 of magnetic core 4, the movement is obstructed by convex portions 4a1 and 4a2, making it difficult for eddy currents to be generated.

[0035] According to the first embodiment, the eddy current generated in the magnetic core 4 of the inductor 1 can be suppressed.

[0036] The first embodiment may be modified as follows.

[0037] 7A and 7B are a left side view and a front view, respectively, of an inductor 1 according to a modification of the first embodiment. The coil 6 is omitted from FIG. 7A. Also, only the vicinity of the protrusion 4a1 is shown in FIG. 7B.

[0038] In the inductor 1 according to the modification of the first embodiment, the protrusions 4a1 are arranged spaced apart in the thickness direction of the magnetic core 4. This modification also achieves the same effects as the first embodiment.

[0039] Second Embodiment The inductor 1 according to the second embodiment differs from the inductor 1 according to the first embodiment in that the width of the convex portions 4a1, 4a2 is constant, whereas the width of the convex portions 4a1, 4a2 becomes narrower as they approach the tips of the convex portions 4a1, 4a2.

[0040] Fig. 4 is a plan view of the inductor 1 according to the second embodiment of the present invention. Fig. 5 is a left side view of the inductor 1 according to the second embodiment. However, in Fig. 5, the coil 6 is omitted.

[0041] The inductor 1 according to the second embodiment includes a magnetic core 4 and a coil 6. The magnetic core 4 has end faces 4E1 and 4E2 and side faces 4S1 to 4S4 (see FIG. 2) that intersect with the end faces 4E1 and 4E2. The coil 6 and the side faces 4S1 to 4S4 are the same as those in the first embodiment, and therefore a description thereof will be omitted.

[0042] The end face 4E1 has a plurality of protrusions 4a1. The end face 4E2 has a plurality of protrusions 4a2. The width W of the protrusions 4a1 and 4a2 is constant. The protrusions 4a1 and 4a2 are spaced apart in the width direction of the magnetic core 4. Other than this, the second embodiment is the same as the first embodiment, and a description thereof will be omitted.

[0043] However, the interval may not be a constant value d but may be a different value. Figure 10A is a partial enlarged view of the convex portion 4a1 in the second embodiment when the interval is a constant value d, and Figure 10B is a partial enlarged view of the convex portion 4a1 in the second embodiment when the interval is different values ​​d1 and d2.

[0044] The case where the interval takes a constant value d (FIG. 10(a)) corresponds to FIG. 4, but it is also possible for the interval to take different values ​​d1 and d2 (FIG. 10(b)). Of course, it is also possible for the interval to take three or more values.

[0045] The operation of the second embodiment is the same as that of the first embodiment, and therefore a description thereof will be omitted.

[0046] According to the second embodiment, the eddy current generated in the magnetic core 4 of the inductor 1 can be suppressed.

[0047] The second embodiment may be modified as follows.

[0048] <Modification> Figures 8A and 8B are a left side view and a front view, respectively, of an inductor 1 according to a modification of the second embodiment. However, in Figure 8A, the coil 6 is omitted. In Figure 8B, only the vicinity of the protrusion 4a1 is shown.

[0049] In the inductor 1 according to the modified example of the second embodiment, the protrusions 4a1 are arranged spaced apart in the thickness direction of the magnetic core 4. This modified example also achieves the same effects as the second embodiment.

[0050] Third Embodiment The inductor 1 according to the third embodiment differs from the inductor 1 according to the first and second embodiments in that the inductor 1 has both convex portions 4a1, 4a2 whose width is constant and convex portions whose width becomes narrower as they approach the tips of the convex portions 4a1, 4a2.

[0051] FIG. 6 is an enlarged plan view of a portion near the protruding portion 4a1 of the inductor 1 according to the third embodiment.

[0052] The inductor 1 according to the third embodiment has both protrusions 4a1 whose widths become narrower toward the tips (see the first embodiment) (the upper three protrusions 4a1) and protrusions 4a1 whose widths are constant (see the second embodiment) (the lower three protrusions 4a1). Other than this, the inductor 1 is similar to the first embodiment, and a description thereof will be omitted.

[0053] The operation of the third embodiment is the same as that of the first embodiment, and therefore a description thereof will be omitted.

[0054] According to the third embodiment, the eddy current generated in the magnetic core 4 of the inductor 1 can be suppressed.

[0055] 1 inductor 2 substrate 4 magnetic core 4E1, 4E2 end faces 4a1, 4a2 convex portions 4S1 to 4S4 side faces 6 coil W width of convex portions d, d1, d2 spacing between convex portions D depth of convex portions

Claims

1. An inductor comprising: a magnetic core having an end face and a side face intersecting the end face, the magnetic core being deposited on a substrate; and a coil winding around the side face, wherein the end face has a plurality of protrusions, the spacing between the protrusions is smaller than the wavelength of an electromagnetic wave generated by an eddy current generated at the end face, and the depth of the protrusions is greater than a predetermined depth at which the current density of the eddy current attenuates to a predetermined rate.

2. An inductor according to claim 1, wherein the predetermined depth is a depth at which the current density of the eddy current is 1 / e of the current density at the end surface (where e is the base of the natural logarithm).

3. An inductor according to claim 1, wherein said spacing is constant.

4. An inductor according to claim 1, wherein said spacing has different values.

5. An inductor according to claim 1, wherein the width of said protrusion becomes narrower as it approaches the tip of said protrusion.

6. An inductor according to claim 1, wherein the width of said protrusion is constant.

7. An inductor according to claim 1, wherein the protrusion has: a width that narrows as it approaches the tip of the protrusion; or a width of the protrusion that is constant.

8. An inductor according to claim 1, wherein the protrusions are arranged spaced apart in the width direction of the magnetic core.

9. An inductor according to claim 1, wherein the protrusions are arranged spaced apart in the thickness direction of the magnetic core.

10. The inductor of claim 1, wherein said magnetic core is one of permendur, FeNi, silicon steel, Ni, and CoFeSiB nanocrystalline materials.

11. An inductor according to claim 1, wherein said magnetic core is formed by sputtering.

12. An inductor according to claim 1, wherein said magnetic core is formed by plating.

Citation Information

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