Coil components

Abstract

To provide a coil component with reduced magnetic resistance at a bent portion of the magnetic field.SOLUTION: A coil component 1 includes a magnetic element M and a coil portion C embedded in the magnetic element M. The magnetic element M includes a region M11 that covers the coil portion C from one side in the coil axial direction, a region M20 that covers the coil portion C from the other side in the coil axial direction, and a region M13 that is provided in the inner diameter region of the coil portion C and connects the region M11 and the region M20. The height of the coil portion C in the coil axial direction becomes smaller as it approaches the inner diameter region. As a result, the angle formed by the magnetic field passing through the regions M11, M20 of the magnetic element M and the magnetic field passing through the region M13 of the magnetic element M is relaxed, such that the magnetic resistance at the bent portion of the magnetic field is reduced.SELECTED DRAWING: Figure 2

Description

Technical Field

[0006] , , ,

[0001] The present invention relates to a coil component and a method for manufacturing the same, and more particularly to a coil component having a structure in which a coil portion is embedded in a magnetic element and a method for manufacturing the same.

Background Art

[0002] Patent Document 1 discloses a coil component having a structure in which a coil portion is embedded in a magnetic element. By using a magnetic material for the element in which the coil portion is embedded as in the coil component described in Patent Document 1, it becomes possible to obtain a small size and a high inductance.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the coil component described in Patent Document 1, since the height in the coil axis direction of the coil portion is substantially constant, a magnetic field perpendicular to the coil axis direction is rapidly bent in the coil axis direction, so that the magnetic resistance becomes high at the bent portion of the magnetic field.

[0005] Therefore, an object of the present invention is to provide a coil component in which the magnetic resistance at the bent portion of the magnetic field is reduced and a method for manufacturing the same.

Means for Solving the Problems

[0006] The coil component according to the present invention comprises a magnetic element and a coil portion embedded in the magnetic element, wherein the magnetic element includes a first region covering the coil portion from one side in the coil axis direction, a second region covering the coil portion from the other side in the coil axis direction, and a third region provided in the inner diameter region of the coil portion and connecting the first region and the second region, and the height of the coil portion in the coil axis direction decreases as it approaches the inner diameter region.

[0007] According to the present invention, since the height of the coil portion in the coil axis direction decreases as it approaches the inner diameter region, the angle between the magnetic field passing through the first or second region of the magnetic element and the magnetic field passing through the third region of the magnetic element is relaxed. As a result, the magnetoresistance at the bending portion of the magnetic field is reduced, and sufficient volume of the magnetic element can be secured.

[0008] In the present invention, the second region of the magnetic element may have an increasing thickness in the coil axis direction as it approaches the inner diameter region. This makes it possible to relax the angle between the magnetic field passing through the second region of the magnetic element and the magnetic field passing through the third region of the magnetic element.

[0009] The coil component according to the present invention may further include a conductor post embedded in a first region of the magnetic element, with one end connected to the coil portion and the other end exposed from the first region of the magnetic element. This makes it possible to mount the coil component so that the coil axis is perpendicular to the circuit board.

[0010] In the present invention, the first region of the magnetic element may have an increasing thickness in the coil axis direction as it approaches the inner diameter region. This makes it possible to relax the angle between the magnetic field passing through the first region of the magnetic element and the magnetic field passing through the third region of the magnetic element.

[0011] The method for manufacturing a coil component according to the present invention is characterized by comprising the steps of: forming a coil portion; forming a first magnetic element on one side of the coil portion in the coil axis direction and in the inner diameter region of the coil portion; deforming the other side of the coil portion in the coil axis direction so that the height of the coil portion in the coil axis direction decreases as it approaches the inner diameter region; and forming a second magnetic element on the other side of the coil portion in the coil axis direction.

[0012] According to the present invention, it is possible to reduce the height of the coil portion in the coil axis direction as it approaches the inner diameter region by a simple method. [Effects of the Invention]

[0013] Thus, according to the present invention, it is possible to provide a coil component in which the magnetic resistance at the bent portion of the magnetic field is reduced, and a method for manufacturing the same. [Brief explanation of the drawing]

[0014] [Figure 1] Figure 1 is a schematic plan view of a coil component 1 according to the first embodiment of the present invention, as seen from the mounting side. [Figure 2] Figure 2 is a schematic cross-sectional view along line AA shown in Figure 1. [Figure 3] Figure 3 is a schematic diagram illustrating the magnetic field generated in the magnetic element M when an electric current is passed through the coil C. [Figure 4] Figure 4 is a process diagram illustrating the manufacturing method of coil component 1. [Figure 5] Figure 5 is a process diagram illustrating the manufacturing method of coil component 1. [Figure 6] Figure 6 is a process diagram illustrating the manufacturing method of coil component 1. [Figure 7] Figure 7 is a process diagram illustrating the manufacturing method of coil component 1. [Figure 8] Figure 8 is a process diagram illustrating the manufacturing method of coil component 1. [Figure 9]FIG. 9 is a process diagram for explaining the manufacturing method of the coil component 1. [Figure 10] FIG. 10 is a process diagram for explaining the manufacturing method of the coil component 1. [Figure 11] FIG. 11 is a process diagram for explaining the manufacturing method of the coil component 1. [Figure 12] FIG. 12 is a process diagram for explaining the manufacturing method of the coil component 1. [Figure 13] FIG. 13 is a process diagram for explaining the manufacturing method of the coil component 1. [Figure 14] FIG. 14 is a process diagram for explaining the manufacturing method of the coil component 1. [Figure 15] FIG. 15 is a process diagram for explaining the manufacturing method of the coil component 1. [Figure 16] FIG. 16 is a process diagram for explaining the manufacturing method of the coil component 1. [Figure 17] FIG. 17 is a process diagram for explaining the manufacturing method of the coil component 1. [Figure 18] FIG. 18 is a process diagram for explaining the manufacturing method of the coil component 1. [Figure 19] FIG. 19 is a schematic plan view of the coil component 1A according to the first modification. [Figure 20] FIG. 20 is a schematic plan view of the coil component 1B according to the second modification. [Figure 21] FIG. 21 is a schematic cross-sectional view showing the configuration of the coil component 2 according to the second embodiment of the present invention. [Figure 22] FIG. 22 is a schematic cross-sectional view showing the configuration of the coil component 3 according to the third embodiment of the present invention.

MODE FOR CARRYING OUT THE INVENTION

[0015] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0016] Figure 1 is a schematic plan view of a coil component 1 according to the first embodiment of the present invention, as seen from the mounting side. Figure 2 is a schematic cross-sectional view along line AA shown in Figure 1.

[0017] As shown in Figures 1 and 2, the coil component 1 according to this embodiment has a structure in which a coil portion C with the coil axis in the Z direction is embedded in a magnetic element M. The magnetic element M includes a region M11 that covers the coil portion C from the +Z direction side, a region M20 that covers the coil portion C from the -Z direction side, a region M13 that is embedded in the inner diameter region of the coil portion C and connects regions M11 and M20, and a region M14 located in the outer region of the coil portion C. Conductor posts P1 and P2 are embedded in region M11 of the magnetic element M.

[0018] The coil section C consists of interlayer insulating films 70-76 and conductor layers L1-L6 that are alternately stacked in the coil axis direction. Each of the conductor layers L1-L6 has a coil pattern 10, 20, 30, 40, 50, and 60, respectively. The coil patterns 10, 20, 30, 40, 50, and 60 are connected in series to form a single coil. One end of the coil is connected to one end (lower end) of conductor post P1, and the other end of the coil is connected to one end (lower end) of conductor post P2. In the example shown in Figure 2, the outer edge of the uppermost coil pattern 60 is connected to conductor post P1, and the outer edge of the lowermost coil pattern 10 is connected to conductor post P2 via connection patterns 21, 31, 41, 51, and 61. The other ends (upper ends) of conductor posts P1 and P2 are exposed from the mounting surface S1. Thus, conductor posts P1 and P2 overlap with the coil section C when viewed from the coil axis direction and are conductors that extend in the coil axis direction.

[0019] The magnetic element M is a composite magnetic member containing a metallic magnetic filler made of iron (Fe) or permalloy-based material and a resin binder, and constitutes the magnetic path of the magnetic flux generated by passing an electric current through coil patterns 10, 20, 30, 40, 50, and 60. Liquid or powdered epoxy resin is preferably used as the resin binder. Furthermore, multiple metallic magnetic fillers with different average particle sizes may be mixed and used as the metallic magnetic filler. This makes it easier to adjust the permeability and fluidity of the magnetic element M. Adjusting the fluidity is important in the deformation of the coil section C by processing using water pressure, as described later.

[0020] As shown in Figure 2, the height of the coil portion C in the coil axis direction decreases as it approaches the inner diameter region. That is, if the height at the outermost position of the coil portion C is H1 and the height at the innermost position of the coil portion C is H2, then H1 > H2. In the example shown in Figure 2, the surface 70a of the interlayer insulating film 70 that constitutes the other side surface of the coil portion C in the coil axis direction has an inclination with respect to a virtual plane V1 perpendicular to the coil axis. The angle between the surface 70a of the interlayer insulating film 70 and the virtual plane V1 is θ1. Thus, in this embodiment, as it approaches the inner diameter region, the surface 70a of the interlayer insulating film 70 has a shape that moves away from the surface S2 opposite to the mounting surface S1. In contrast, since surface S2 is almost flat and almost perpendicular to the coil axis, the thickness of the region M20 of the magnetic element M increases in the coil axis direction as it approaches the inner diameter region.

[0021] Figure 3 is a schematic diagram illustrating the magnetic field generated in the magnetic element M when an electric current is passed through the coil C.

[0022] As shown in Figure 3, when current is passed through the coil section C, a magnetic field is generated that circulates in the order (or reverse order) of regions M11, M14, M20, and M13 of the magnetic element M. In this embodiment, since the cross-sectional shape of the coil section C is H1 > H2, the angle between the surface 70a of the interlayer insulating film 70 and the surface 77a of the inner diameter region is obtuse. As a result, the bending angle of the magnetic field bent from region M20 to region M13 (or from region M13 to region M20) of the magnetic element M is relaxed, which reduces the concentration of the magnetic field at the corner of surfaces 70a and 77a, and thus reduces the magnetoresistance in this area. The corner of surfaces 70a and 77a is the region where the magnetic flux density is highest, and by reducing the magnetoresistance in this region, the inductance is significantly increased. Moreover, the thickness of region M20 of the magnetic element M in the coil axis direction increases as it approaches the inner diameter region. As a result, sufficient volume is secured in the region M20 of the magnetic element M, making it possible to obtain a higher inductance compared to the case where H1=H2.

[0023] Here, the angle θ1 formed by the surface 70a of the interlayer insulating film 70 and the virtual surface V1 is preferably 0.1° or more and 5° or less. This is because if the angle θ1 is less than 0.1°, the effect of reducing magnetic resistance cannot be sufficiently obtained. Furthermore, when using the method described later, it is difficult to deform the coil portion C so that the angle θ1 exceeds 5°.

[0024] Next, a description will be given of the method for manufacturing the coil component 1 according to this embodiment.

[0025] Figures 4 to 17 are process diagrams illustrating the manufacturing method of the coil component 1 according to this embodiment.

[0026] First, a substrate is prepared in which copper foil 91 is formed on the surface of a support 90, and the thickness of the copper foil 91 in the position overlapping with the coil portion C is selectively reduced by etching or the like (Figure 4). Next, the surface of the copper foil 91 is covered with an interlayer insulating film 70 (Figure 5), and then a conductive layer L1 is formed on the surface of the interlayer insulating film 70 (Figure 6). As shown in Figure 6, at this point the conductive layer L1 contains a sacrificial pattern 92. Then, the coil portion C is formed by repeating the process shown in Figures 5 and 6 (Figure 7). Here, the sacrificial patterns 92 contained in each conductive layer L1 to L6 are not separated by the interlayer insulating films 71 to 75, but are in contact with each other.

[0027] Next, after forming the resist 93 (Figure 8), conductive posts P1 and P2 are formed by electroplating (Figure 9). This forms conductive posts P1 and P2 on one side of the coil section C in the coil axis direction. Next, after covering the conductive posts P1 and P2 with resist 94 (Figure 10), the sacrificial pattern 92 is removed by etching with acid or by laser treatment (Figure 11). This leaves the inner diameter region of the coil section C hollow. Although not shown, a sacrificial pattern 92 is also formed in the outer region of the coil section C, and removing this also leaves the outer region of the coil section C hollow.

[0028] Next, a fluid magnetic element M10 is formed on one side of the coil portion C in the coil axis direction, in the inner diameter region of the coil portion C, and in the outer region of the coil portion C, so that the coil portion C and the conductor posts P1 and P2 are embedded (Figure 12). The magnetic element M10 has a region M11 located on one side of the coil portion C in the coil axis direction, a region M13 located in the inner diameter region of the coil portion C, and a region M14 located in the outer region of the coil portion C, but only regions M11 and M13 are visible in the cross-section shown in Figure 12.

[0029] Next, after pre-hardening the magnetic element M10, its surface is ground to expose the surfaces of the conductor posts P1 and P2 (Figure 13). Then, after peeling off the support 90 (Figure 14), the copper foil 91 is removed by etching to expose the interlayer insulating film 70 (Figure 15). Finally, by performing a desmear treatment on the interlayer insulating film 70 to reduce its thickness, the regions M13 and M14 of the magnetic element M10 located in the inner diameter region and outer region of the coil section C are exposed (Figure 16).

[0030] Next, a pre-hardened magnetic element M20 is attached to the other side of the coil section C in the coil axis direction (Figure 17). As a result, the coil section C is sandwiched axially by region M11 of the magnetic element M10 and the magnetic element M20, and the two are magnetically connected by regions M13 and M14. Next, with the entire structure sandwiched between plates 95 and 96, the entire structure is pressurized using water pressure or the like to harden the partially hardened magnetic element M10. As a result, region M13 of the partially hardened magnetic element M10 is compressed, and as shown in Figure 2, the interface between region M13 and region M20 curves, and the coil section C deforms accordingly, with the height in the coil axis direction decreasing as it approaches the inner diameter region. Regions M11 and M20 are fixed by plates 95 and 96 respectively, so almost no deformation occurs. After that, the coil component 1 according to this embodiment is completed by fully hardening and fragmenting the magnetic element M.

[0031] Thus, in this embodiment, since the entire structure is sandwiched between plates 95 and 96 and pressurized using water pressure or the like, it is possible to deform the coil section C into the shape shown in Figure 2. To make the angle θ1 shown in Figure 2 larger, after performing the process shown in Figure 16, as shown in Figure 18, if the entire structure is pressurized using water pressure or the like while only the region M11 side of the magnetic element M is fixed with plate 96, the other side of the coil section C in the coil axis direction will deform more significantly, such that the height of the coil section C in the coil axis direction decreases as it approaches the inner diameter region. After deforming the coil section C in this way, if the magnetic element M20 is formed as shown in Figure 17, it becomes possible to use a magnetic element M20 with a larger volume.

[0032] Furthermore, the conductor posts P1 and P2 may be exposed not only from the mounting surface S1 but also from the YZ side, as shown in the first modified coil component 1A in Figure 19. This makes it possible to form solder fillets on the YZ side when the coil component 1A is mounted on a circuit board. In addition, the planar shape of the conductor posts P1 and P2 exposed on the mounting surface S1 does not need to be rectangular; it may be circular, as shown in the second modified coil component 1B in Figure 20.

[0033] Figure 21 is a schematic cross-sectional view showing the configuration of a coil component 2 according to a second embodiment of the present invention.

[0034] As shown in Figure 21, the coil component 2 according to the second embodiment differs from the coil component 1 according to the first embodiment in that the surface 76a of the interlayer insulating film 70, which constitutes one side of the surface of the coil portion C in the coil axis direction, is inclined with respect to a virtual plane V2 perpendicular to the coil axis. The angle between the surface 76a of the interlayer insulating film 76 and the virtual plane V2 is θ2, and is preferably between 0.1° and 5°. Thus, in this embodiment, the surface 76a of the interlayer insulating film 76 moves away from the mounting surface S1 as it approaches the inner diameter region. In contrast, the mounting surface S1 is almost flat and almost perpendicular to the coil axis, so the thickness of the region M11 of the magnetic element M increases in the coil axis direction as it approaches the inner diameter region. The other basic configurations are the same as those of the coil component 1 according to the first embodiment, so the same reference numerals are used for the same elements, and redundant explanations are omitted.

[0035] As illustrated by this embodiment, the coil portion C may have deformed surfaces on both sides in the coil axis direction. This reduces the bending angle of the magnetic field that bends from region M11 to region M13 (or from region M13 to region M11) of the magnetic element M, thereby reducing the concentration of the magnetic field at the corners of surfaces 76a and 77a, and lowering the magnetoresistance in this area. Moreover, since sufficient volume is secured in region M11 of the magnetic element M, it becomes possible to obtain a higher inductance.

[0036] Figure 22 is a substantially cross-sectional view showing the configuration of the coil component 3 according to the third embodiment of the present invention.

[0037] As shown in Figure 22, the coil component 3 according to the third embodiment differs from the coil component 1 according to the first embodiment in that, instead of omitting the conductor posts P1 and P2, a portion of the conductor layers L1 to L6 is exposed on the YZ side surface of the magnetic element M, and this is used as a terminal electrode. Since the other basic configurations are the same as those of the coil component 1 according to the first embodiment, the same reference numerals are used for the same elements, and redundant explanations are omitted. As illustrated by this embodiment, it is not necessarily required to use the conductor posts P1 and P2 in the present invention.

[0038] Although preferred embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to the above embodiments, and various modifications are possible without departing from the spirit of the invention, and these modifications are also included within the scope of the present invention.

[0039] For example, the configuration of the coil section C is not limited to the above embodiment, and a common mode filter may be constructed by alternately stacking two coils with an interlayer insulating film in between. [Explanation of Symbols]

[0040] Coil components 1-3, 1A, 1B 10, 20, 30, 40, 50, 60 coil patterns 21, 31, 41, 51, 61 Connection Patterns 70-76 Interlayer insulating film Surface of the interlayer insulating film 70a, 76a 77a Surface of the inner diameter region 90 Support 91 Copper foil 92 Sacrifice Patterns 93,94 Resist 95,96 Plate C Coil section L1~L6 conductor layer M,M10,M20 Magnetic element M11,M13,M14 area P1, P2 Conductor Posts S1 Implementation side S2 is the surface opposite to the mounting side. V1, V2 Virtual Surfaces

Claims

1. Magnetic element and, The magnetic element comprises a coil portion embedded in the aforementioned magnetic element, The coil portion includes a first interlayer insulating film constituting one surface in the coil axis direction, a second interlayer insulating film constituting the other surface in the coil axis direction, and a plurality of coil patterns located between the first interlayer insulating film and the second interlayer insulating film, which are stacked in the coil axis direction via a plurality of third interlayer insulating films. The magnetic element includes a first region covering one side surface of the coil portion, a second region covering the other side surface of the coil portion, and a third region provided in the inner diameter region of the coil portion and connecting the first region and the second region. The surface of the other side of the coil portion has a greater inclination with respect to a virtual plane perpendicular to the coil axis than the surface of the one side of the coil portion, and as a result, the height of the coil portion in the coil axis direction decreases as it approaches the inner diameter region.

2. The coil component according to claim 1, characterized in that the second region of the magnetic element increases in thickness in the coil axial direction as it approaches the inner diameter region.

3. The coil component according to claim 1 or 2, further comprising a conductor post embedded in the first region of the magnetic element, one end of which is connected to the coil portion, and the other end of which is exposed from the first region of the magnetic element.

4. The coil component according to claim 2, characterized in that the thickness of the first region of the magnetic element increases in the coil axial direction as it approaches the inner diameter region.

5. The coil component according to claim 1, characterized in that both the surface on one side and the surface on the other side of the coil portion are flat.

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