Coil parts

Abstract

To provide a coil component with a structure in which a bump electrode is exposed from an upper surface and a side surface of a magnetic body layer, and volume of the magnetic body layer is secured sufficiently.SOLUTION: A coil component 1 includes a coil part 2, a magnetic element assembly M covering the coil part 2, and bump electrodes B1 and B2 connected to the coil part 2 and embedded in the magnetic element assembly M. The magnetic element assembly M includes an upper surface 3 orthogonal to an axis direction of the coil part 2 and a side surface 4 orthogonal to the upper surface 3. The bump electrodes B1 and B2 include a first exposed part S1 exposed from the upper surface 3 and a second exposed part S2 exposed from the side surface 4. A width W2 of the second exposed part S2 in a y direction is narrower than a width W1 of the first exposed part S1 in the y direction. Thus, volume of the magnetic element assembly M can be secured sufficiently.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a coil component, and more particularly to a coil component having a structure in which a coil portion is covered with a magnetic element. [Background technology]

[0002] Patent Document 1 discloses a coil component including a coil portion formed on the surface of a magnetic substrate, a magnetic layer covering the coil portion, and a bump electrode embedded in the magnetic layer. According to the coil component described in Patent Document 1, since the bump electrode is surrounded by the magnetic layer, it is possible to obtain high inductance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4922353 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the coil component described in Patent Document 1 has a problem in that the bump electrodes are exposed not only from the top surface of the magnetic layer but also from the side surfaces, which reduces the volume of the magnetic layer accordingly.

[0005] Therefore, an object of the present invention is to ensure a sufficient volume of the magnetic layer in a coil component having a structure in which bump electrodes are exposed from the top and side surfaces of the magnetic layer. [Means for solving the problem]

[0006] The coil component according to the present invention comprises a coil portion formed by alternately stacking a plurality of interlayer insulating films and a plurality of conductor layers, a magnetic layer covering the coil portion, and a bump electrode connected to the coil portion and embedded in the magnetic layer, wherein the magnetic layer has an upper surface perpendicular to the axial direction of the coil portion and a side surface perpendicular to the upper surface, the bump electrode has a first exposed portion exposed from the upper surface of the magnetic layer and a second exposed portion exposed from the side surface of the magnetic layer, and the maximum width of the second exposed portion in a first direction perpendicular to the axial direction is narrower than the maximum width of the first exposed portion in the first direction.

[0007] According to the present invention, since the exposed width of the second exposed portion is narrower than the exposed width of the first exposed portion, it is possible to ensure a sufficient volume of the magnetic layer.

[0008] The coil component according to the present invention may further include an electrode pattern that is provided on the upper surface of the magnetic layer so as to cover the first exposed portion of the bump electrode and has an area larger than that of the first exposed portion. This allows the bump electrode to be made smaller, thereby enabling the volume of the magnetic layer to be further increased.

[0009] In the present invention, the first exposed portion of the bump electrode may have a circular or polygonal first portion and a second portion connecting the first portion and the second exposed portion. This configuration reduces the likelihood of voids occurring in the bump electrode even when the bump electrode has a large aspect ratio when formed by electrolytic plating. Since the bump electrode is formed by forming a resist pattern having a negative pattern of the bump electrode and then performing electrolytic plating, if the aspect ratio is the ratio of the resist thickness to the bump electrode diameter of the resist pattern, the larger the aspect ratio, the more likely void defects are to occur in the bump electrode. However, with the above configuration, the aspect ratio is reduced by the second portion, reducing the likelihood of voids occurring in the bump electrode. In this case, the width of the second portion in the first direction may be constant or may narrow toward the second exposed portion. The former configuration makes it easier to ensure the volume of the magnetic layer, while the latter configuration reduces the likelihood of voids occurring in the bump electrode. [Effects of the Invention]

[0010] Thus, according to the present invention, in a coil component having a structure in which bump electrodes are exposed from the top and side surfaces of the magnetic layer, it is possible to ensure a sufficient volume of the magnetic layer. [Brief explanation of the drawings]

[0011] [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 perspective view showing the coil device 1 with the terminal electrodes E1 and E2 removed. [Figure 3] FIG. 3 is a schematic perspective view for explaining the shape of the bump electrode B1. [Figure 4] FIG. 4 is a schematic perspective view for explaining the shape of a bump electrode B1 according to a modified example. [Figure 5] FIG. 5 is a schematic cross-sectional view of the coil device 1. As shown in FIG. [Figure 6] 6(a) to 6(d) are schematic plan views for explaining the pattern shapes of the conductor layers L1 to L4, respectively. [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 process diagram illustrating a method for manufacturing the coil component 1. [Figure 11] FIG. 11 is a process diagram illustrating a method for manufacturing the coil device 1. [Figure 12] FIG. 12 is a process diagram illustrating a method for manufacturing the coil device 1. [Figure 13] FIG. 13 is a process diagram illustrating a method for manufacturing the coil device 1. [Figure 14] FIG. 14 is a process diagram illustrating a method for manufacturing the coil device 1. [Figure 15] FIG. 15 is a process diagram illustrating a method for manufacturing the coil device 1. [Figure 16] FIG. 16 is a process diagram illustrating a method for manufacturing the coil device 1. [Figure 17] FIG. 17 is a process chart illustrating a manufacturing method of coil device 1 according to a first modified example. [Figure 18] FIG. 18 is a process chart illustrating a manufacturing method of coil device 1 according to a second modified example. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0013] FIG. 1 is a schematic perspective view illustrating the appearance of a coil component 1 according to one embodiment of the present invention.

[0014] 1, coil component 1 according to this embodiment has a structure in which a coil portion 2 with its coil axis in the z direction is embedded in a magnetic body M. Magnetic body M has an upper surface 3 that is orthogonal to the coil axis and forms an xy plane, and a side surface 4 that is orthogonal to upper surface 3 and forms a yz plane. Terminal electrodes E1 and E2 are provided on upper surface 3, and during mounting, terminal electrodes E1 and E2 are soldered to a circuit board so that upper surface 3 faces the circuit board.

[0015] FIG. 2 is a schematic perspective view showing the coil device 1 with the terminal electrodes E1 and E2 removed.

[0016] As shown in Fig. 2, bump electrodes B1 and B2 are exposed in the portions covered by terminal electrodes E1 and E2, respectively. 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. The bump electrodes B1 and B2 are embedded in the magnetic element M, and a part thereof is exposed not only from the upper surface 3 of the magnetic element M but also from the side surface 4.

[0017] Fig. 3 is a schematic perspective view for explaining the shape of the bump electrode B1.

[0018] As shown in Fig. 3, the bump electrode B1 has a columnar portion B11 with the z direction as the axial direction and a protruding portion B12 protruding in the x direction from the columnar portion B11. Then, the xy plane of the columnar portion B11 and the protruding portion B12 constitutes a first exposed portion S1 exposed from the upper surface 3 of the magnetic element M, and the yz plane of the protruding portion B12 constitutes a second exposed portion S2 exposed from the side surface 4 of the magnetic element M. The first exposed portion S1 consists of a first portion S11 that belongs to the columnar portion B11 and is circular, and a second portion S12 that belongs to the protruding portion B12. The width of the first portion S11 in the y direction is W1, and the width of the second portion S12 in the y direction is W2 (<W1). The width W1 is the maximum width of the first exposed portion S1 in the y direction. In the example shown in Fig. 3, the width W2 of the second portion S12 in the y direction is constant, and therefore, the width of the second exposed portion S2 in the y direction is also W2 (<W1). The bump electrode B2 also has the same shape as the bump electrode B1.

[0019] As described above, in this embodiment, the width W2 in the y direction of the second exposed portion S2 of the bump electrodes B1, B2 is narrower than the width W1 in the y direction of the first exposed portion S1, so the volume of the magnetic body M is increased compared to when the width W2 is the same as the width W1. Moreover, the area of the terminal electrodes E1, E2 is larger than the area of the first exposed portion S1 of the bump electrodes B1, B2, so the size of the bump electrodes B1, B2 can be reduced. This makes it possible to increase inductance while ensuring sufficient terminal area. Moreover, because the first portion S11 is composed of the cylindrical portion B11, plating liquid circulates easily when forming the bump electrodes B1, B2 by electroplating, making it less likely that voids will occur.

[0020] However, the width W2 of the second portion S12 in the y direction does not need to be constant, and the width of the second portion S12 in the y direction may be narrower toward the second exposed portion S2, as in the modified example shown in Fig. 4. If the bump electrodes B1, B2 have such a shape, the plating liquid circulates more easily, making it less likely that voids will occur.

[0021] FIG. 5 is a schematic cross-sectional view of the coil device 1 according to the present embodiment.

[0022] 5, 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. The magnetic body M is made up of magnetic layers M1-M4. Of these, the magnetic layer M1 covers the coil portion 2 from one side in the coil axis direction, the magnetic layer M2 is provided in the inner diameter region of the coil portion 2, the magnetic layer M3 is provided in the outer region of the coil portion 2, and the magnetic layer M4 covers the coil portion 2 from the other side in the coil axis direction. The bump electrodes B1 and B2 described above are embedded in the magnetic layer M4, and terminal electrodes E1 and E2 are formed on the upper surface 3 of the magnetic layer M4.

[0023] The conductor layers L1 to L4 respectively have coil patterns 10, 20, 30, and 40. The magnetic body M is a composite magnetic member containing a metal magnetic filler made of iron (Fe), permalloy-based material, or the like, and a resin binder, and forms a magnetic path for magnetic flux generated by passing a current through the coil patterns 10, 20, 30, and 40. As the resin binder, it is preferable to use a liquid or powdered epoxy resin.

[0024] 6(a) to 6(d) are schematic plan views for explaining the pattern shapes of the conductor layers L1 to L4, respectively.

[0025] 6(a) to 6(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.

[0026] As described above, in the coil component 1 according to this embodiment, the bump electrodes B1, B2 are exposed not only on the top surface 3 but also on the side surfaces 4 of the magnetic layer M4, and the exposed width W2 on the side surfaces 4 is smaller than the exposed width W1 on the top surface 3, making it possible to ensure a sufficient volume of the magnetic body M. Furthermore, the second exposed portion S2 exposed on the side surfaces 4 not only improves the heat dissipation properties of the coil component 1, but can also be used as a directionality mark.

[0027] Next, a method for manufacturing the coil component 1 according to this embodiment will be described.

[0028] 7 to 16 are process diagrams illustrating a method for manufacturing coil component 1 according to this embodiment.

[0029] First, the coil portion 2 is formed by alternately forming interlayer insulating films 50-54 and conductor layers L1-L4 on the surface of the substrate 61, and then vias 71 and 72 are formed in the interlayer insulating film 54 (FIG. 7). The conductor layers L1-L4 can be formed by electrolytic plating. The via 71 is formed in a position that exposes the connection pattern 41, and the via 72 is formed in a position that exposes the outer peripheral end 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 region of the coil portion 2.

[0030] Next, a resist pattern 80 is formed on the surface of the interlayer insulating film 54 (FIG. 8). The resist pattern 80 has an opening 81 that exposes the via 71 and an opening 82 that exposes the via 72. FIG. 9 is a schematic plan view illustrating the shape of the resist pattern 80. The dashed lines Dx and Dy in FIG. 9 are dicing lines, and the collective substrate is ultimately cut along the dicing lines Dx and Dy to separate the coil components 1. Therefore, the area surrounded by the dicing lines Dx and Dy corresponds to one coil component 1. As shown in FIG. 9, an opening 81 belonging to a certain coil component 1 and an opening 82 belonging to an adjacent coil component 1 in the x direction are connected via an opening 83. In other words, the opening 83 is located on the dicing line Dy.

[0031] After forming the resist pattern 80 having such a shape, electrolytic plating is performed. As a result, bump electrodes B1 and B2 are formed in the openings 81 and 82 of the resist pattern 80, respectively (FIG. 10). FIG. 11 is a schematic plan view illustrating the shape of the bump electrodes B1 and B2. As shown in FIG. 11, the planar shapes of the bump electrodes B1 and B2 match the planar shapes of the openings 81 to 83 of the resist pattern 80. Here, the portion of the opening 83 of the resist pattern 80 located inside the dicing line Dy constitutes part of the bump electrodes B1 and B2. Here, in order to form void-free bump electrodes B1 and B2 by electrolytic plating, it is necessary to properly circulate a plating solution through the openings 81 and 82 of the resist pattern 80. In this embodiment, the openings 81 and 82 of two coil components 1 adjacent in the x direction are connected via the opening 83, which promotes circulation of the plating solution within the openings 81 and 82. This makes it possible to form bump electrodes B1, B2 without voids even when the aspect ratio, which is the ratio of the thickness of the resist pattern 80 to the width W1 of the bump electrodes B1, B2, is relatively large.

[0032] Next, after covering the bump electrodes B1 and B2 with a resist pattern 90 (FIG. 12), the sacrificial patterns 62 and 63 are removed by wet etching (FIG. 13). The conductor pattern constituting the coil portion 2 is not etched because it is covered with the interlayer insulating films 50 to 54. As a result, a space S is formed in the inner diameter region and outer diameter region of the coil portion 2. Next, the space S formed by removing the sacrificial patterns 62 and 63 is filled with magnetic layers M2 to M4 (FIG. 14). Then, after removing the base material 61 (FIG. 15), the magnetic layer M1 is formed so as to cover the interlayer insulating film 50 (FIG. 16). At this time, the magnetic layer M1 may be brought into contact with the magnetic layers M2 and M3 by removing the interlayer insulating film 50 that overlaps the inner diameter region and outer diameter region of the coil portion 2. Then, after dividing the substrate into individual pieces along the dicing lines Dx and Dy shown in FIG. 11, terminal electrodes E1 and E2 are formed by applying a conductive paste to the upper surface 3 of the magnetic layer M4, thereby completing the coil component 1 according to this embodiment.

[0033] As described above, in this embodiment, when the bump electrodes B1, B2 are formed by electrolytic plating, the openings 81, 82 of two coil components 1 adjacent in the x direction are connected by the opening 83, which promotes circulation of the plating liquid within the openings 81, 82. This makes it possible to form bump electrodes B1, B2 without voids. Moreover, the width of the opening 83 in the y direction is narrower than the width of the openings 81, 82 in the y direction, which makes it possible to ensure a sufficient volume for the magnetic layer M4.

[0034] 7, the interlayer insulating film 50 may be left in the portion that overlaps with the protruding portion B12 in plan view, as shown in FIG. 17. This increases the overall strength of the coil component 1. In the process shown in FIG. 9, openings 81 and 82 belonging to a certain coil component 1 may be connected to openings 81 and 82 belonging to a coil component 1 adjacent thereto in the y direction by an opening 83, as shown in FIG. 18. This allows the plating liquid to circulate more easily, making it less likely that voids will occur.

[0035] 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.

[0036] For example, in the above embodiment, the first portion S11 of the first exposed portion S1 is circular, but the present invention is not limited to this, and it may be polygonal. [Explanation of symbols]

[0037] 1 Coil parts 2 Coil section 3. Top surface of magnetic element (magnetic layer) 4 Side of magnetic element (magnetic layer) 10, 20, 30, 40 coil patterns 21,31,41 connection patterns 50~54 Interlayer insulating film 61 Base material 62,63 Sacrifice Pattern 71,72 Via 80 Resist Pattern 81~83 Opening 90 Resist Pattern B1, B2 bump electrodes B11 Cylindrical part B12 Projecting part Dx,Dy dicing line E1,E2 terminal electrode L1~L4 conductor layers M magnetic element M1~M4 Magnetic layer S space S1 First exposed part S11 First part S12 Second part S2 Second exposed part

Claims

1. a coil portion in which a plurality of interlayer insulating films and a plurality of conductor layers are alternately stacked; a magnetic layer covering the coil portion; a bump electrode connected to the coil portion and embedded in the magnetic layer, the magnetic layer has an upper surface perpendicular to the axial direction of the coil portion and a side surface perpendicular to the upper surface, the bump electrode has a first exposed portion exposed from the top surface of the magnetic layer and a second exposed portion exposed from the side surface of the magnetic layer, a maximum width of the second exposed portion in a first direction perpendicular to the axial direction is narrower than a maximum width of the first exposed portion in the first direction; the first exposed portion of the bump electrode has a first portion that is circular or polygonal and a second portion that connects the first portion and the second exposed portion; A coil component, characterized in that the width of the second portion in the first direction is constant.

2. 2. The coil component according to claim 1, further comprising an electrode pattern provided on the upper surface of the magnetic layer so as to cover the first exposed portion of the bump electrode, the electrode pattern having an area larger than that of the first exposed portion.

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