JP7722902B2 - Coil parts - Google Patents

Description

The present invention relates to coil components, and in particular to coil components having a structure in which the coil portion is covered with a magnetic base material.

Patent Document 1 discloses a coil component that includes a coil portion formed on the surface of a magnetic substrate, a magnetic layer that covers the coil portion, and a bump electrode embedded in the magnetic layer. With the coil component described in Patent Document 1, the bump electrode is surrounded by the magnetic layer, making it possible to obtain high inductance.

Patent No. 4922353

However, the coil component described in Patent Document 1 has bump electrodes exposed not only from the top surface of the magnetic layer but also from the side surfaces, which poses a problem of reducing the volume of the magnetic layer.

Therefore, the present invention aims to ensure 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.

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

According to the present invention, the exposed width of the second exposed portion is narrower than the exposed width of the first exposed portion, making it possible to ensure sufficient volume of the magnetic layer.

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 a larger area than the first exposed portion. This allows the bump electrode to be made smaller, thereby making it possible to further increase the volume of the magnetic layer.

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 reduces the likelihood of voids occurring in the bump electrode when the bump electrode is formed by electrolytic plating, even if the bump electrode has a large aspect ratio. In other words, 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 alleviated by the second portion, making voids less likely to occur 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 makes it easier to ensure the volume of the magnetic layer, while the latter reduces the likelihood of voids occurring in the bump electrode.

In this way, according to the present invention, it is possible to ensure 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.

FIG. 1 is a schematic perspective view for explaining the appearance of a coil component 1 according to an embodiment of the present invention. FIG. 2 is a schematic perspective view showing the coil component 1 with the terminal electrodes E1 and E2 removed. FIG. 3 is a schematic perspective view for explaining the shape of the bump electrode B1. FIG. 4 is a schematic perspective view for explaining the shape of a bump electrode B1 according to a modified example. FIG. 5 is a schematic cross-sectional view of the coil component 1. 6A to 6D are schematic plan views for explaining the pattern shapes of the conductor layers L1 to L4, respectively. FIG. 7 is a process diagram for explaining the method of manufacturing the coil component 1. FIG. 8 is a process diagram for explaining the method for manufacturing the coil component 1. FIG. 9 is a process diagram for explaining the method for manufacturing the coil component 1. FIG. 10 is a process diagram for explaining the method for manufacturing the coil component 1. FIG. 11 is a process diagram for explaining the method for manufacturing the coil component 1. FIG. 12 is a process diagram for explaining the method for manufacturing the coil component 1. FIG. 13 is a process diagram for explaining the method for manufacturing the coil component 1. FIG. 14 is a process diagram for explaining the method for manufacturing the coil component 1. FIG. 15 is a process diagram for explaining the method for manufacturing the coil component 1. FIG. 16 is a process diagram for explaining the method for manufacturing the coil component 1. FIG. 17 is a process chart for explaining a manufacturing method of the coil component 1 according to a first modified example. FIG. 18 is a process diagram illustrating a manufacturing method of the coil component 1 according to a second modified example.

A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

Figure 1 is a simplified perspective view illustrating the appearance of a coil component 1 according to one embodiment of the present invention.

As shown in FIG. 1, the 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. The 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 the upper surface 3 and forms a yz plane. Terminal electrodes E1 and E2 are provided on the upper surface 3, and when mounted, the terminal electrodes E1 and E2 are soldered to the circuit board so that the upper surface 3 faces the circuit board.

Figure 2 is a simplified perspective view showing the coil component 1 with terminal electrodes E1 and E2 removed.

As shown in Figure 2, bump electrodes B1 and B2 are exposed in the areas covered by terminal electrodes E1 and E2, respectively. Bump electrodes B1 and B2 are pillar-shaped conductors made of Cu or the like, and serve to connect both ends of coil portion 2 to terminal electrodes E1 and E2. Bump electrodes B1 and B2 are embedded in magnetic base body M, and are partially exposed not only from the top surface 3 of magnetic base body M, but also from the side surface 4.

Figure 3 is a schematic perspective view illustrating the shape of the bump electrode B1.

As shown in FIG. 3, the bump electrode B1 has a cylindrical portion B11 whose axial direction is the z direction, and a protruding portion B12 that protrudes from the cylindrical portion B11 in the x direction. The xy planes of the cylindrical portion B11 and the protruding portion B12 form a first exposed portion S1 that is exposed from the top surface 3 of the magnetic body M, and the yz plane of the protruding portion B12 forms a second exposed portion S2 that is exposed from the side surface 4 of the magnetic body M. The first exposed portion S1 consists of a circular first portion S11 that belongs to the cylindrical portion B11, 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). 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 W2 of the second exposed portion S2 in the y direction is also W2 (< W1). The bump electrode B2 also has a shape similar to that of the bump electrode B1.

In this embodiment, the width W2 in the y direction of the second exposed portion S2 of the bump electrodes B1 and B2 is narrower than the width W1 in the y direction of the first exposed portion S1, thereby increasing the volume of the magnetic body M compared to when width W2 is the same as width W1. Furthermore, because the area of the terminal electrodes E1 and E2 is larger than the area of the first exposed portion S1 of the bump electrodes B1 and B2, the size of the bump electrodes B1 and B2 can be reduced. This makes it possible to increase inductance while ensuring sufficient terminal area. Furthermore, because the first portion S11 is composed of the cylindrical portion B11, plating liquid circulates more easily when forming the bump electrodes B1 and B2 by electrolytic plating, making it less likely that voids will form.

However, the width W2 of the second portion S12 in the y direction does not need to be constant; as in the modified example shown in Figure 4, the width of the second portion S12 in the y direction may be narrower toward the second exposed portion S2. If the bump electrodes B1 and B2 are shaped in this way, the plating liquid can circulate more easily, making it less likely that voids will occur.

Figure 5 is a schematic cross-sectional view of the coil component 1 according to this embodiment.

As shown in FIG. 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 base body M is made up of magnetic layers M1-M4. Of these, magnetic layer M1 covers the coil portion 2 from one side in the coil axis direction, magnetic layer M2 is provided in the inner diameter region of the coil portion 2, magnetic layer M3 is provided in the outer region of the coil portion 2, and magnetic layer M4 covers the coil portion 2 from the other side in the coil axis direction. The above-mentioned bump electrodes B1 and B2 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.

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

Figures 6(a) to 6(d) are schematic plan views illustrating the pattern shapes of conductor layers L1 to L4, respectively.

As shown in Figures 6(a) to 6(d), coil pattern 10 is provided on conductor layer L1, coil pattern 20 and connection pattern 21 are provided on conductor layer L2, coil pattern 30 and connection pattern 31 are provided on conductor layer L3, and coil pattern 40 and connection pattern 41 are provided on conductor layer L4. Connection patterns 21, 31, and 41 are shorted to each other and connect the outer peripheral edge of coil pattern 10 to bump electrode B1. The inner peripheral edge of coil pattern 10 is connected to the inner peripheral edge of coil pattern 20, the outer peripheral edge of coil pattern 20 is connected to the outer peripheral edge of coil pattern 30, the inner peripheral edge of coil pattern 30 is connected to the inner peripheral edge of coil pattern 40, and the outer peripheral edge of coil pattern 40 is connected to bump electrode B2. As a result, coil patterns 10, 20, 30, and 40 are connected in series between terminal electrodes E1 and E2.

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 sufficient volume for the magnetic base 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 directional mark.

Next, we will explain the manufacturing method of the coil component 1 according to this embodiment.

Figures 7 to 16 are process diagrams illustrating the manufacturing method of the coil component 1 according to this embodiment.

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 (Figure 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.

Next, a resist pattern 80 is formed on the surface of the interlayer insulating film 54 (Figure 8). The resist pattern 80 has an opening 81 that exposes the via 71 and an opening 82 that exposes the via 72. Figure 9 is a schematic plan view illustrating the shape of the resist pattern 80. The dashed lines Dx and Dy in Figure 9 are dicing lines, and the coil components 1 are ultimately separated by cutting the aggregate substrate along the dicing lines Dx and Dy. Therefore, the area surrounded by the dicing lines Dx and Dy corresponds to one coil component 1. As shown in Figure 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.

After forming the resist pattern 80 having this 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 (Figure 10). Figure 11 is a schematic plan view illustrating the shape of the bump electrodes B1 and B2. As shown in Figure 11, the planar shapes of the bump electrodes B1 and B2 match the planar shapes of the openings 81-83 of the resist pattern 80. 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. Forming void-free bump electrodes B1 and B2 by electrolytic plating requires proper circulation of plating liquid 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 plating liquid within the openings 81 and 82. This makes it possible to form bump electrodes B1 and 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 and B2, is relatively large.

Next, after covering the bump electrodes B1 and B2 with a resist pattern 90 (Figure 12), wet etching is performed to remove the sacrificial patterns 62 and 63 (Figure 13). The conductor pattern constituting the coil portion 2 is not etched because it is covered with the interlayer insulating films 50-54. This leaves a space S in the inner diameter region and outer region of the coil portion 2. Next, the space S formed by the removal of the sacrificial patterns 62 and 63 is filled with magnetic layers M2-M4 (Figure 14). Then, after removing the substrate 61 (Figure 15), a magnetic layer M1 is formed to cover the interlayer insulating film 50 (Figure 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 region of the coil portion 2. After the substrate is diced 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, completing the coil component 1 according to this embodiment.

In this manner, in this embodiment, when forming bump electrodes B1, B2 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 plating liquid within the openings 81, 82. This makes it possible to form bump electrodes B1, B2 without voids. Moreover, because the width of the opening 83 in the y direction is narrower than the width of the openings 81, 82 in the y direction, it is possible to ensure sufficient volume for the magnetic layer M4.

In the process shown in FIG. 7, the interlayer insulating film 50 may be left in the portion that overlaps 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, the openings 81 and 82 belonging to a certain coil component 1 may be connected to the openings 81 and 82 belonging to the coil component 1 adjacent to it 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.

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 without departing from the spirit of the present invention, and it goes without saying that these modifications are also included within the scope of the present invention.

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 may be polygonal.

1 Coil component 2 Coil portion 3 Top surface of magnetic body (magnetic body layer) 4 Side surface of magnetic body (magnetic body layer) 10, 20, 30, 40 Coil patterns 21, 31, 41 Connection patterns 50 to 54 Interlayer insulating film 61 Base material 62, 63 Sacrificial patterns 71, 72 Via 80 Resist patterns 81 to 83 Opening 90 Resist patterns B1, B2 Bump electrode B11 Cylindrical portion B12 Protruding portions Dx, Dy Dicing lines E1, E2 Terminal electrodes L1 to L4 Conductor layer M Magnetic body M1 to M4 Magnetic body layer S Space S1 First exposed portion S11 First portion S12 Second portion S2 Second exposed portion

Claims (2)

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 . The coil component described in claim 1, further comprising an electrode pattern provided on the upper surface of the magnetic layer to cover the first exposed portion of the bump electrode, the electrode pattern having a larger area than the first exposed portion.