Coil component and manufacturing method thereof

Abstract

To provide a coil component having such a structure that a coil part is embedded by a magnetic element assembly which prevents occurrence of chipping at corner parts of the magnetic element assembly.SOLUTION: A coil component 1 includes a coil part 2, magnetic body layers M11 to M13 arranged in an inner diameter region, an outside region and one side in an axial direction of a coil part 2, and a magnetic body layer M20 arranged on the other side in the axial direction of the coil part 2. The magnetic body layers M11 to M13 and M20 are each composed of a composite magnetic material containing a magnetic filler and a binder resin, and percentage contents of the magnetic fillers in the magnetic body layers M11 to M13 are higher than a percentage content of the magnetic filler in the magnetic body layer M20. Thereby, mechanical strength of the magnetic body layer M20 is enhanced, which can prevent occurrence of chipping on the magnetic body layer M20 side.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a coil component and a manufacturing method thereof, and more particularly to a coil component having a structure in which a coil portion including a spiral coil pattern is embedded in a magnetic element, and a manufacturing method thereof. [Background technology]

[0002] 10 of Patent Document 1 discloses a coil component having a structure in which a coil portion including a spiral coil pattern is embedded in a magnetic element made of a composite magnetic material. In Patent Document 1, the average particle size of the magnetic filler on the front and back portions of the magnetic element is made smaller than the average particle size of the magnetic filler in other portions, thereby suppressing a decrease in the volume of the magnetic element due to the magnetic filler falling off. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-054144 Summary of the Invention [Problem to be solved by the invention]

[0004] However, simply reducing the average particle size of the magnetic filler on the front and back of the magnetic base body is not sufficient to prevent the magnetic filler from falling off, and it is difficult to adequately prevent chipping at the corners of the magnetic base body that occurs during manufacturing.

[0005] Therefore, the present invention aims to suppress the falling off of magnetic filler and prevent chipping at the corners of the magnetic base body in a coil component having a structure in which a coil portion including a spiral coil pattern is embedded in a magnetic base body, and in a manufacturing method thereof. [Means for solving the problem]

[0006] The coil component according to the present invention comprises a coil section in which a plurality of conductor layers and a plurality of insulating layers, each including a spiral coil pattern, are alternately stacked, a first magnetic layer arranged in an inner diameter region, an outer region and one side in the axial direction of the coil section, and a second magnetic layer arranged on the other side in the axial direction of the coil section, wherein the first and second magnetic layers are both made of a composite magnetic material containing a magnetic filler and a binder resin, and the magnetic filler content in the first magnetic layer is higher than the magnetic filler content in the second magnetic layer.

[0007] According to the present invention, the mechanical strength of the second magnetic layer is increased, which makes it possible to prevent the magnetic filler from falling off or chipping on the second magnetic layer side, while the first magnetic layer has higher magnetic properties, which makes it possible to increase the inductance of the coil section.

[0008] In the present invention, the material and average particle size of the magnetic filler contained in the first magnetic layer may be the same as the material and average particle size of the magnetic filler contained in the second magnetic layer, which makes it possible to reduce material costs.

[0009] In the present invention, the first magnetic resin and the second magnetic resin are in contact with each other, and the binder resin material contained in the first magnetic layer may be the same as the binder resin material contained in the second magnetic layer, thereby improving the adhesion between the first magnetic resin and the second magnetic resin.

[0010] The coil component according to the present invention may further include a bump electrode connected to the coil portion, the bump electrode being embedded in the first magnetic layer and exposed from a surface of the first magnetic layer perpendicular to the axial direction. Although the use of such a bump electrode reduces the volume of the magnetic base body, the high content of magnetic filler in the first magnetic layer makes it possible to suppress a decrease in inductance.

[0011] In the present invention, the surface of the second magnetic layer perpendicular to the axial direction may have a smaller surface roughness than the surface of the first magnetic layer, which makes it easier to pick up the surface of the second magnetic layer when mounting the coil component on a circuit board.

[0012] A method for manufacturing a coil component according to the present invention includes the steps of forming a coil portion by alternately stacking a plurality of conductor layers and a plurality of insulating layers, each including a spiral coil pattern, on a support substrate; forming a first magnetic layer in the inner diameter region, the outer region, and one axial side of the coil portion; removing the support substrate and then forming a second magnetic layer on the other axial side of the coil portion; and dicing the first and second magnetic layers from one axial side to separate the components, wherein the first and second magnetic layers are both made of a composite magnetic material containing a magnetic filler and a binder resin, and the magnetic filler content in the first magnetic layer is higher than the magnetic filler content in the second magnetic layer.

[0013] According to the present invention, it is possible to prevent chipping of the corners of the magnetic element body, which is likely to occur at the end of cutting during dicing. [Effects of the Invention]

[0014] Thus, according to the present invention, in a coil component having a structure in which a coil portion including a spiral coil pattern is embedded in a magnetic base material, and in a method for manufacturing the same, it is possible to suppress the falling off of the magnetic filler and prevent chipping from occurring at the corners of the magnetic base material. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic perspective view illustrating the appearance of a coil component 1 according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view of the coil device 1. As shown in FIG. [Figure 3] 3(a) to 3(d) are schematic plan views for explaining the pattern shapes of the conductor layers L1 to L4, respectively. [Figure 4] FIG. 4 is a process diagram illustrating a method for manufacturing the coil component 1. [Figure 5] FIG. 5 is a process diagram illustrating a method for manufacturing the coil component 1. [Figure 6] FIG. 6 is a process diagram illustrating a method for manufacturing the coil component 1. [Figure 7] FIG. 7 is a process diagram illustrating a method for manufacturing the coil component 1. [Figure 8] FIG. 8 is a process diagram illustrating a method for manufacturing the coil component 1. [Figure 9] FIG. 9 is a process diagram illustrating a method for manufacturing the coil device 1. [Figure 10] FIG. 10 is a schematic perspective view illustrating the appearance of a coil device 1A according to a modified example. [Figure 11] FIG. 11 is a schematic cross-sectional view of the coil device 1A. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0017] FIG. 1 is a schematic perspective view illustrating the appearance of a coil component 1 according to one embodiment of the present invention.

[0018] 1, coil component 1 according to this embodiment has a structure in which coil portion 2, whose coil axis is in the z direction, is embedded in magnetic body M. Magnetic body M has surfaces 3 and 4 that are orthogonal to the coil axis and form an xy plane. Terminal electrodes E1 and E2 are provided on surface 3, and during mounting, terminal electrodes E1 and E2 are soldered to the circuit board so that surface 3 faces the circuit board.

[0019] FIG. 2 is a schematic cross-sectional view of the coil device 1 according to the present embodiment.

[0020] As shown in Fig. 2, the coil component 1 according to this embodiment has a coil portion 2 made up of interlayer insulating films 50-54 and conductor layers L1-L4 alternately stacked in the coil axis direction (z direction). The magnetic body M is made up of magnetic layers M11-M13, M20. Of these, the magnetic layer M11 is provided in the inner diameter region of the coil portion 2, the magnetic layer M12 is provided in the outer diameter region of the coil portion 2, the magnetic layer M13 covers the coil portion 2 from one side in the coil axis direction, and the magnetic layer M20 covers the coil portion 2 from the other side in the coil axis direction. The magnetic layer M20 is in contact with the magnetic layer M11 in a portion overlapping the inner diameter region of the coil portion 2, and is in contact with the magnetic layer M12 in a portion overlapping the outer region of the coil portion 2. Meanwhile, the magnetic layers M11-M13 are integrated. Here, it is preferable that the contact area between the magnetic body layers M20 and M12 be approximately the same as or larger than the contact area between the magnetic body layers M20 and M11, which makes it less likely that chipping will occur at corners during the manufacturing process described below.

[0021] Bump electrodes B1 and B2 are embedded in the magnetic layer M13. The bump electrodes B1 and B2 are exposed at least from the surface 3, and terminal electrodes E1 and E2 are formed on the surface 3 of the magnetic body M so as to contact the bump electrodes B1 and B2 exposed from the surface 3. The bump electrodes B1 and B2 are pillar-shaped conductors made of Cu or the like, and serve to connect both ends of the coil portion 2 to the terminal electrodes E1 and E2.

[0022] The conductor layers L1 to L4 have coil patterns 10, 20, 30, and 40, respectively. The magnetic layers M11 to M13, and M20 that make up the magnetic body M are made of a composite magnetic material containing a magnetic filler and a binder resin. As the magnetic filler, it is preferable to use a metallic magnetic material such as iron (Fe) or a permalloy-based material. As the binder resin, it is preferable to use an epoxy resin. The magnetic body M forms a magnetic path for magnetic flux generated by passing a current through the coil patterns 10, 20, 30, and 40.

[0023] Here, the magnetic layers M11 to M13 are made of the same composite magnetic material, while the magnetic layer M20 is made of a different composite magnetic material from the magnetic layers M11 to M13. In this embodiment, the magnetic filler content in the magnetic layers M11 to M13 is higher than the magnetic filler content in the magnetic layer M20. In other words, the binder resin content in the magnetic layer M20 is higher than the binder resin content in the magnetic layers M11 to M13. For example, the magnetic filler content in the magnetic layers M11 to M13 is 97.8 wt %, and the binder resin content is 2.2 wt %, while the magnetic filler content in the magnetic layer M20 is 97.4 wt %, and the binder resin content is 2.6 wt %.

[0024] This allows the magnetic layers M11 to M13 to have higher magnetic permeability, while allowing the magnetic layer M20 to have higher mechanical strength. For example, if the magnetic filler content in the magnetic layers M11 to M13 is 97.8 wt% and the binder resin content is 2.2 wt%, the magnetic permeability will be approximately 62 and the bending strength will be 73 MPa. If the magnetic filler content in the magnetic layer M20 is 97.4 wt% and the binder resin content is 2.6 wt%, the magnetic permeability will be approximately 55 and the bending strength will be 96 MPa.

[0025] In this embodiment, the magnetic layers M11 to M13, which constitute most of the magnetic body M, have high magnetic permeability, resulting in high inductance. In particular, the magnetic flux density is highest in the inner diameter region of the coil portion 2, so embedding the magnetic layer M11 in this region can increase inductance. Furthermore, because bump electrodes B1 and B2 are embedded in the magnetic layer M13, the volume of the magnetic layer M13 is reduced, thereby reducing inductance. However, by using a material with high magnetic permeability for the magnetic layer M13, high inductance can be achieved. In contrast, the magnetic layer M20 has a reduced magnetic filler content and an increased binder resin content. This prevents chipping, which is likely to occur at corners during the manufacturing process described below, and also prevents the magnetic filler from falling off.

[0026] The material and average particle size of the magnetic filler contained in the magnetic layers M11 to M13 may be the same as or different from the material and average particle size of the magnetic filler contained in the magnetic layer M20. However, if the material and average particle size are the same for both, not only can material costs be reduced, but also it becomes easier to adjust the magnetic permeability and mechanical strength by changing the content of the magnetic filler.

[0027] The binder resin material contained in the magnetic layers M11 to M13 may be the same as or different from the binder resin material contained in the magnetic layer M20. However, using the same material for both not only reduces material costs but also improves adhesion between the magnetic layers M11, M12 and M20.

[0028] 3(a) to 3(d) are schematic plan views for explaining the pattern shapes of the conductor layers L1 to L4, respectively.

[0029] 3(a) to 3(d), a coil pattern 10 is provided on the conductor layer L1, a coil pattern 20 and a connection pattern 21 are provided on the conductor layer L2, a coil pattern 30 and a connection pattern 31 are provided on the conductor layer L3, and a coil pattern 40 and a connection pattern 41 are provided on the conductor layer L4. The connection patterns 21, 31, and 41 are short-circuited with each other and connect the outer circumferential end of the coil pattern 10 to a bump electrode B1. The inner circumferential end of the coil pattern 10 is connected to the inner circumferential end of the coil pattern 20, the outer circumferential end of the coil pattern 20 is connected to the outer circumferential end of the coil pattern 30, the inner circumferential end of the coil pattern 30 is connected to the inner circumferential end of the coil pattern 40, and the outer circumferential end of the coil pattern 40 is connected to the bump electrode B2. As a result, the coil patterns 10, 20, 30, and 40 are connected in series between the terminal electrodes E1 and E2.

[0030] Next, a method for manufacturing the coil component 1 according to this embodiment will be described.

[0031] 4 to 9 are process diagrams illustrating the method for manufacturing the coil component 1 according to this embodiment. Although only a portion corresponding to one coil component 1 is shown in Fig. 4 to 8, in reality, a plurality of coil components 1 are simultaneously manufactured using an aggregate substrate.

[0032] First, as shown in FIG. 4, interlayer insulating films 50-54 and conductor layers L1-L4 are alternately formed on the surface of a support substrate 61 to form the coil portion 2, and then vias 71 and 72 are formed in the interlayer insulating film 54. The conductor layers L1-L4 can be formed by electroplating. The via 71 is formed at a position that exposes the connection pattern 41, and the via 72 is formed at a position that exposes the outer peripheral edge of the coil pattern 40. The conductor layers L1-L4 also include a sacrificial pattern 62 located in the inner diameter region of the coil portion 2 and a sacrificial pattern 63 located in the outer peripheral region of the coil portion 2. Next, bump electrodes B1 and B2 are formed on the surface of the interlayer insulating film 54 by electroplating. As a result, the bump electrode B1 is connected to the connection pattern 41 via the via 71, and the bump electrode B2 is connected to the outer peripheral edge of the coil pattern 40 via the via 72.

[0033] Next, as shown in FIG. 5, the sacrificial patterns 62 and 63 are removed by wet etching. The conductor patterns constituting the coil portion 2 are not etched because they are covered with the interlayer insulating films 50 to 54. The bump electrodes B1 and B2 must be covered with a resist pattern to prevent etching. As a result, a space S is formed in the inner diameter region and outer diameter region of the coil portion 2. Next, as shown in FIG. 6, the space S formed by removing the sacrificial patterns 62 and 63 is filled with magnetic layers M11 to M13. Then, after removing the support substrate 61 as shown in FIG. 7, a magnetic layer M20 is formed to cover the interlayer insulating film 50 as shown in FIG. 8. Here, if the lower surface of the interlayer insulating film 50 is roughened before forming the magnetic layer M20, the adhesion between the magnetic layer M20 and the interlayer insulating film 50 can be improved. In other words, since the magnetic layers M11 to M13 are formed to embed the coil section 2 having an uneven shape, sufficient adhesion can be ensured even if the surface roughness of the upper surface of the interlayer insulating film 54 is small, while the magnetic layer M20 is formed on the flat surface of the coil section 2, and therefore adhesion can be ensured by making the surface roughness of the lower surface of the interlayer insulating film 50 greater than the surface roughness of the upper surface of the interlayer insulating film 54.

[0034] Then, as shown in FIG. 9 , an aggregate substrate 80 including a plurality of coil components 1 is attached to a dicing tape 81, and the aggregate substrate 80 is cut with a blade 82 along dicing lines D to separate the coil components 1. The cutting using the blade 82 is performed from the surface 3 side of the magnetic body M. That is, surface 4 of the magnetic body M opposite surface 3 is attached to the dicing tape 81, with surface 3 being the cutting start side and surface 4 being the cutting end side. In this case, as cutting using the blade 82 progresses, the remaining thickness of the aggregate substrate 80 decreases, causing stress to concentrate below the dicing lines D, and chipping may occur in surface 4 when the blade 82 reaches the vicinity of surface 4. However, in the coil component 1 according to this embodiment, the mechanical strength of the magnetic body layer M20 constituting surface 4 is increased, making it possible to prevent chipping of the corners of the magnetic body M, which is likely to occur at the end of dicing.

[0035] Furthermore, once dicing is complete, the individual coil components 1 are peeled off from the dicing tape 81, and even during this process, chipping is likely to occur at the corners of the magnetic body M. However, in this embodiment, the mechanical strength of the magnetic body layer M20 is increased, so it is possible to prevent such chipping that occurs when the dicing tape 81 is peeled off.

[0036] In this embodiment, the mechanical strength is increased by increasing the binder resin content of the magnetic body layer M20 located at the cutting end side during dicing, which makes it possible to prevent chipping at the corners of the magnetic body, which is likely to occur at the cutting end. Also, if the size of the aggregate substrate 80 is large, warping is likely to occur during manufacturing, but if the binder resin material contained in the magnetic body layers M11 to M13 and the binder resin material contained in the magnetic body layer M20 are the same, warping of the aggregate substrate 80 due to differences in thermal expansion coefficients is less likely to occur.

[0037] The coil component 1 thus fabricated is picked up using a chip mounter and mounted on a circuit board. In this case, the surface 4 located opposite the surface 3 on which the bump electrodes B1 and B2 are provided serves as the attraction surface, and therefore the surface 4 of the magnetic layer M20 may be polished so that the surface roughness of the surface 4 is smaller than that of the surface 3.

[0038] Fig. 10 is a schematic perspective view illustrating the appearance of a coil device 1A according to a modified example, and Fig. 11 is a schematic cross-sectional view of the coil device 1A.

[0039] 10 and 11 differs from the coil component 1 according to the above-described embodiment in that, instead of providing bump electrodes B1, B2, portions of the conductor layers L1 to L4 are exposed from a side surface 5 constituting the xz plane and side surfaces 6, 7 constituting the yz plane of the magnetic body M, and terminal electrodes E1, E2 are formed on the side surfaces 5 to 7. Since the other basic configuration is the same as that of the coil component 1, the same elements are given the same reference numerals and redundant explanations will be omitted.

[0040] As illustrated by the coil component 1A according to the modified example, it is not essential to use bump electrodes in the present invention, and terminal electrodes E1, E2 may be provided on the side surfaces 5 to 7 of the magnetic body M.

[0041] The above describes a preferred embodiment of the present invention, but the present invention is not limited to the above embodiment, and various modifications are possible within the scope of the present invention, and it goes without saying that these modifications are also included within the scope of the present invention. [Explanation of symbols]

[0042] 1.1A coil parts 2 Coil section 3,4 Surface of magnetic body 5-7 Side of magnetic element 10, 20, 30, 40 coil patterns 21,31,41 connection patterns 50~54 Interlayer insulating film 61 Support substrate 62,63 Sacrifice Pattern 71,72 Via 80 assembly board 81 Dicing Tape 82 Blade B1, B2 bump electrodes D Dicing Line E1,E2 terminal electrode L1~L4 conductor layers M magnetic element M11~M13,M20 Magnetic layer S space

Claims

1. a coil portion in which a plurality of conductor layers including a spiral coil pattern and a plurality of insulating layers are alternately laminated; a first magnetic layer disposed in an inner diameter region, an outer region, and one side in the axial direction of the coil portion; a second magnetic layer disposed on the other side of the coil portion in the axial direction, the first and second magnetic layers are each made of a composite magnetic material containing a magnetic filler and a binder resin; a content of the magnetic filler in the first magnetic layer is higher than a content of the magnetic filler in the second magnetic layer; the plurality of insulating layers include a first insulating layer located closest to the other side in the axial direction of the coil portion, the lower surface of which is in contact with the second magnetic layer, A coil component, wherein the lower surface of the first insulating layer is roughened.

2. 2. The coil component according to claim 1, wherein the material and average particle size of the magnetic filler contained in the first magnetic layer are the same as the material and average particle size of the magnetic filler contained in the second magnetic layer.

3. the first magnetic layer and the second magnetic layer are in contact with each other, 3. The coil component according to claim 1, wherein the material of the binder resin contained in the first magnetic layer is the same as the material of the binder resin contained in the second magnetic layer.

4. further comprising a bump electrode connected to the coil portion; 4. The coil component according to claim 1, wherein the bump electrode is embedded in the first magnetic layer and is exposed from a surface of the first magnetic layer in a direction perpendicular to the axial direction.

5. The coil component according to claim 4 , wherein the surface of the second magnetic layer perpendicular to the axial direction has a surface roughness smaller than that of the surface of the first magnetic layer.

6. A coil component described in any one of claims 1 to 5, characterized in that the contact area between the portion of the first magnetic layer arranged in the outer region of the coil portion and the second magnetic layer is approximately the same as the contact area between the portion of the first magnetic layer arranged in the inner diameter region of the coil portion and the second magnetic layer.

7. A coil component described in any one of claims 1 to 5, characterized in that the contact area between the portion of the first magnetic layer arranged in the outer region of the coil portion and the second magnetic layer is larger than the contact area between the portion of the first magnetic layer arranged in the inner diameter region of the coil portion and the second magnetic layer.

8. forming a coil portion by alternately stacking a plurality of conductor layers and a plurality of insulating layers, each including a spiral coil pattern, on a support substrate; forming a first magnetic layer in an inner diameter region, an outer region, and one axial side of the coil portion; After removing the support substrate, a step of roughening a lower surface of a first insulating layer located furthest to the other side in the axial direction of the coil portion among the plurality of insulating layers; forming a second magnetic layer on the other side of the coil portion in the axial direction so as to cover the lower surface of the first insulating layer; and a step of dicing the first and second magnetic layers from the one side in the axial direction to separate the first and second magnetic layers into individual pieces, the first and second magnetic layers are each made of a composite magnetic material containing a magnetic filler and a binder resin; A method for manufacturing a coil component, characterized in that the content of the magnetic filler in the first magnetic layer is higher than the content of the magnetic filler in the second magnetic layer.

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