Coil component and method for manufacturing the same

Abstract

To provide a coil component having a structure that a coil layer where a plurality of conductor layers and a plurality of interlayer insulating layers are alternately laminated is embedded in a magnetic elemental body which prevents plating adhesion to an unnecessary part and exposure of coil conductor patterns.SOLUTION: A coil component 1 includes: a magnetic elemental body 10 composed of a resin containing conductive magnetic powder; a coil part 20 where a plurality of conductor layers 31 to 34 including coil conductor patterns C1 to C4 embedded in the magnetic elemental body 10 and electrode patterns 51 to 54 and 61 to 64 exposed from the magnetic elemental body 10, and a plurality of interlayer insulating layers 40 to 44 are alternately laminated; external terminals E1 and E2 provided on the electrode patterns 51 to 54 and 61 to 64; and a protective insulating layer 70 covering the magnetic elemental body 10 so as to expose the external terminals E1 and E2. Thus, since the magnetic elemental body 10 is covered with the protective insulating layer 70, even when electrolytic plating is applied to surfaces of the external terminals E1 and E2, plating adhesion to an unnecessary part and exposure of the coil conductor patterns are prevented.SELECTED DRAWING: Figure 2

Description

Technical Field

[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 layer formed by alternately laminating a plurality of conductor layers and a plurality of interlayer insulating layers is embedded in a magnetic element, and a method for manufacturing the same.

Background Art

[0002] As a coil component having a structure in which a coil layer formed by alternately laminating a plurality of conductor layers and a plurality of interlayer insulating layers is embedded in a magnetic element, a coil component described in Patent Document 1 is known. In the coil component described in Patent Document 1, a magnetic element made of a resin containing magnetic powder such as ferrite powder or metal magnetic powder is used.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when the magnetic powder used for the magnetic element has conductivity, there is a problem that plating is also formed on the surface of the magnetic element when external terminals are formed by electrolytic plating. As a method for solving this problem, a method of softly etching the surface of the magnetic element before performing electrolytic plating can be considered. However, if the magnetic element is excessively etched, the coil conductor pattern embedded in the magnetic element may be exposed.

[0005] Therefore, an object of the present invention is to prevent plating adhesion to unnecessary portions and exposure of the coil conductor pattern in a coil component having a structure in which a coil layer formed by alternately laminating a plurality of conductor layers and a plurality of interlayer insulating layers is embedded in a magnetic element.

Means for Solving the Problems

[0006] The coil component according to the present invention includes a magnetic element made of a resin containing conductive magnetic powder, a plurality of conductor layers including a coil conductor pattern embedded in the magnetic element and an electrode pattern exposed from the magnetic element, and a plurality of interlayer insulating layers alternately laminated, a coil part, an external terminal provided on the electrode pattern, and a protective insulating layer covering the magnetic element so that the external terminal is exposed.

[0007] According to the present invention, since the magnetic element is covered with the protective insulating layer, even when electrolytic plating is applied to the surface of the external terminal, it is possible to prevent plating adhesion to unnecessary portions and exposure of the coil conductor pattern.

[0008] In the present invention, the protective insulating layer may cover the entire surface of the magnetic element. According to this, it is possible to more reliably prevent plating formation on unnecessary portions and exposure of the coil conductor pattern.

[0009] In the present invention, the surface of the magnetic element may have irregularities due to protruding or falling conductive magnetic powder, and the protective insulating layer may be provided so as to fill the irregularities. According to this, it is possible to enhance the adhesion between the magnetic element and the protective insulating layer.

[0010] In the present invention, the surface of the external terminal and the surface of the protective insulating layer located around the external terminal may form the same plane. According to this, it is possible to prevent unnecessary spreading of solder during mounting.

[0011] In the present invention, the external terminal may be made of a conductive paste. According to this, no plating film adheres to the surface of the magnetic element when the external terminal is formed.

[0012] In the present invention, the external terminal may be exposed on a surface perpendicular to the lamination direction of the conductor layer and the interlayer insulating layer, and may be provided over the entire width in the lamination direction. According to this, the mounting strength when mounted on a circuit board using solder or the like is enhanced.

[0013] The manufacturing method of the coil component according to the present invention includes a step of forming a coil layer by alternately laminating a plurality of conductor layers including a coil conductor pattern and an electrode pattern and a plurality of interlayer insulating layers, a step of embedding the coil layer with a magnetic element made of a resin containing conductive magnetic powder, a step of exposing the electrode pattern by fragmenting or grinding the magnetic element, a step of applying an external terminal on the electrode pattern, a step of covering the surfaces of the magnetic element and the external terminal with a protective insulating layer, and a step of exposing the external terminal by grinding the protective insulating layer.

[0014] According to the present invention, since the external terminal is formed by application, unlike the case where the external terminal is formed by electrolytic plating, it is not necessary to perform soft etching on the magnetic element.

Advantages of the Invention

[0015] Thus, according to the present invention, in a coil component having a structure in which a coil layer formed by alternately laminating a plurality of conductor layers and a plurality of interlayer insulating layers is embedded in a magnetic element, it is possible to prevent the formation of plating on unnecessary portions and the exposure of the coil conductor pattern.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0018] FIG. 1 is a schematic perspective view showing the appearance of the coil component 1 according to a preferred embodiment of the present invention. Further, FIG. 2 is a cross-sectional view of the coil component 1 taken along the xy plane, and FIG. 3 is a cross-sectional view of the coil component 1 taken along the line A-A shown in FIG. 2.

[0019] The coil component 1 according to the present embodiment is a surface-mount chip component suitable for use as an inductor for a power supply circuit. As shown in FIGS. 1 to 3, it includes a magnetic element 10 composed of magnetic layers 11 to 14, a coil portion 20 embedded in the magnetic element 10, a protective insulating layer 70 covering the surface of the magnetic element 10, and external terminals E1 and E2 exposed from the protective insulating layer 70. The configuration of the coil portion 20 will be described later, but in the present embodiment, four conductor layers having a coil conductor pattern are laminated to form one coil. One end of the coil is connected to the external terminal E1, and the other end of the coil is connected to the external terminal E2.

[0020] The magnetic element 10 is a composite member made of a resin containing electrically conductive magnetic powder such as ferrite powder or metal magnetic powder, and constitutes a magnetic path for magnetic flux generated by passing an electric current through the coil. When using metal magnetic powder as the magnetic powder, it is preferable to use a permalloy-based material. Further, as the resin, it is preferable to use a liquid or powder epoxy resin.

[0021] Unlike general multilayer coil components, the coil component 1 according to this embodiment is mounted upright so that the z-direction, which is the stacking direction, is parallel to the circuit board. Specifically, the surface S1 that constitutes the xz plane is used as the mounting surface. And from the surface S1, the external terminals E1 and E2 are exposed. The other surfaces are entirely covered with the protective insulating layer 70. The external terminals E1 and E2 are made of a conductive paste such as a nano silver paste or a nano copper paste. The surfaces of the external terminals E1 and E2 exposed from the protective insulating layer 70 are covered with a laminated film of nickel (Ni) and tin (Sn) to ensure wettability with solder.

[0022] The protective insulating layer 70 protects the magnetic element 10 and plays a role in preventing the conductive magnetic powder contained in the magnetic element 10 from falling off. The surface of the magnetic element 10 has irregularities due to protruding or fallen conductive magnetic powder, and the protective insulating layer 70 covers the surface of the magnetic element 10 so as to fill these irregularities. Thereby, the adhesion between the magnetic element 10 and the protective insulating layer 70 is enhanced. Although it is preferable that the protective insulating layer 70 covers the entire surface of the magnetic element 10, the magnetic element 10 may be partially exposed.

[0023] As shown in FIG. 2, the mounting surface, that is, the surface S1, has a recess between the external terminal E1 and the external terminal E2. This is due to the manufacturing process described later. By providing such a recess, the creepage distance between the external terminal E1 and the external terminal E2 increases, so that short-circuit failures are less likely to occur. Also, the main body portions of the external terminals E1 and E2, that is, the portions made of the conductive paste, do not protrude from the protective insulating layer 70, and the surfaces of the external terminals E1 and E2 and the surface of the protective insulating layer 70 located around the external terminals E1 and E2 form the same plane. Thereby, it is possible to prevent the solder from spreading more than necessary during mounting. Regarding the laminated film of nickel (Ni) and tin (Sn) formed on the surfaces of the external terminals E1 and E2, it may slightly protrude from the surface of the protective insulating layer 70.

[0024] As shown in FIG. 3, the coil portion 20 has a structure in which the interlayer insulating layers 40 to 44 and the conductor layers 31 to 34 are alternately laminated. The conductor layers 31 to 34 are connected to each other through through-holes formed in the interlayer insulating layers 41 to 43 to form a coil. One side in the axial direction of the coil portion 20 is covered with the magnetic layer 11, the other side in the axial direction of the coil portion 20 is covered with the magnetic layer 12, and the inner diameter region of the coil portion 20 is filled with the magnetic layer 13. Further, as shown in FIG. 2, the outer region of the coil portion 20 is covered with the magnetic layer 14. These magnetic layers 11 to 14 may be made of the same composite material as each other, or some of them may be made of different composite materials.

[0025] The interlayer insulating layers 40 to 44 are made of, for example, resin, and a non-magnetic material is used for at least the interlayer insulating layers 41 to 43. For the interlayer insulating layer 40 located at the lowermost layer and the interlayer insulating layer 44 located at the uppermost layer, a magnetic material may be used.

[0026] The conductor layer 31 is the first-layer conductor layer formed on the upper surface of the magnetic layer 11 with the interlayer insulating layer 40 interposed therebetween. The conductor layer 31 is provided with a coil conductor pattern C1 wound in a spiral shape for two turns and two electrode patterns 51 and 61. The coil conductor pattern C1 is embedded in the magnetic element 10, and the electrode patterns 51 and 61 are exposed from the magnetic element 10. The electrode pattern 51 is connected to the outer peripheral end of the coil conductor pattern C1, while the electrode pattern 61 is provided independently of the coil conductor pattern C1.

[0027] The conductor layer 32 is the second conductor layer formed on the upper surface of the conductor layer 31 with an interlayer insulating layer 41 therebetween. The conductor layer 32 is provided with a coil conductor pattern C2 wound spirally for two turns and two electrode patterns 52 and 62. The coil conductor pattern C2 is embedded in the magnetic element 10, and the electrode patterns 52 and 62 are exposed from the magnetic element 10. The inner peripheral end of the coil conductor pattern C2 is connected to the inner peripheral end of the coil conductor pattern C1 through a via provided in the interlayer insulating layer 41. The electrode patterns 52 and 62 are both provided independently of the coil conductor pattern C2.

[0028] The conductor layer 33 is the third conductor layer formed on the upper surface of the conductor layer 32 with an interlayer insulating layer 42 therebetween. The conductor layer 33 is provided with a coil conductor pattern C3 wound spirally for two turns and two electrode patterns 53 and 63. The coil conductor pattern C3 is embedded in the magnetic element 10, and the electrode patterns 53 and 63 are exposed from the magnetic element 10. The outer peripheral end of the coil conductor pattern C3 is connected to the outer peripheral end of the coil conductor pattern C2 through a via provided in the interlayer insulating layer 42. The electrode patterns 53 and 63 are both provided independently of the coil conductor pattern C3.

[0029] The conductor layer 34 is the fourth conductor layer formed on the upper surface of the conductor layer 33 with an interlayer insulating layer 43 therebetween. The conductor layer 34 is provided with a coil conductor pattern C4 wound spirally for two turns and two electrode patterns 54 and 64. The coil conductor pattern C4 is embedded in the magnetic element 10, and the electrode patterns 54 and 64 are exposed from the magnetic element 10. The electrode pattern 64 is connected to the outer peripheral end of the coil conductor pattern C4, while the electrode pattern 54 is provided independently of the coil conductor pattern C4. The inner peripheral end of the coil conductor pattern C4 is connected to the inner peripheral end of the coil conductor pattern C3 through a via provided in the interlayer insulating layer 43.

[0030] As a result, an 8-turn coil is formed by the coil conductor patterns C1 to C4, one end of which is connected to the external terminal E1 and the other end of which is connected to the external terminal E2.

[0031] Furthermore, the electrode patterns 51 to 54 are connected to each other via via conductors V1 to V3 provided through the interlayer insulating layers 41 to 43. Similarly, the electrode patterns 61 to 64 are connected to each other via via conductors V4 to V6 provided through the interlayer insulating layers 41 to 43. Here, the formation positions of the via conductors V1 to V3 as viewed from the stacking direction are different from each other, and the formation positions of the via conductors V4 to V6 as viewed from the stacking direction are also different from each other. In the cross section shown in FIG. 3, the electrode patterns 51 to 54 and 61 to 64 are covered with the protective insulating layer 70.

[0032] Thus, in the coil component 1 according to the present embodiment, since the entire surface of the magnetic element 10 is covered with the protective insulating layer 70, it is possible to prevent the conductive magnetic powder contained in the magnetic element 10 from falling off. Moreover, since the external terminals E1 and E2 are exposed only on the surface S1 which is the mounting surface, it is possible to prevent the solder from spreading more than necessary during mounting. Further, since the surface S1 has a recess between the external terminal E1 and the external terminal E2, the creepage distance between the external terminal E1 and the external terminal E2 is increased, and it is possible to prevent a short-circuit failure.

[0033] Next, a method for manufacturing the coil component 1 according to the present embodiment will be described.

[0034] FIGS. 4 to 6 are process diagrams for explaining the manufacturing process of the coil component 1 according to the present embodiment.

[0035] First, as shown in FIG. 4(a), a support substrate S having a predetermined strength is prepared, and the interlayer insulating layers 40 to 44 and the conductor layers 31 to 34 are alternately formed on its surface. The formation of the interlayer insulating layers 40 to 44 can be performed by applying a resin material by a spin coating method. Also, the formation of the conductor layers 31 to 34 can be performed by forming an underlying metal film using a thin film process such as a sputtering method and then growing the plating to a desired film thickness using an electrolytic plating method.

[0036] Next, as shown in FIG. 4(b), by removing the interlayer insulating layers 40 to 44 and the conductor layers 31 to 34 located in the inner diameter region surrounded by the coil conductor patterns C1 to C4 and the outer region located outside the coil conductor patterns C1 to C4, a space is formed. Then, as shown in FIG. 4(c), by embedding a composite member made of a resin containing conductive magnetic powder in this space, the magnetic element 10 is formed. Next, as shown in FIG. 4(d), dicing is performed for singulation. As a result, a part of the electrode patterns 51 to 54 and 61 to 64 is exposed from the cut surface. The step of exposing the electrode patterns 51 to 54 and 61 to 64 may be performed by grinding the surface of the magnetic element 10 after singulation.

[0037] Next, as shown in FIG. 5, by applying a conductive paste onto the electrode patterns 51 to 54 and 61 to 64, the external terminals E1 and E2 are formed. If the external terminals E1 and E2 are formed by applying a conductive paste, it is not necessary to perform soft etching on the magnetic element 10 in advance as in the case of forming the external terminals E1 and E2 by electrolytic plating. Next, as shown in FIG. 6, the entire surface of the magnetic element 10 is covered with a protective insulating layer 70. As a method for forming the protective insulating layer 70, a dip coating method, a spray coating method, an electrostatic spraying method, etc. can be used. In any method, the unevenness on the surface of the magnetic element 10 is filled by the protective insulating layer 70, and the two are firmly adhered. At this stage, the external terminals E1 and E2 are also covered with the protective insulating layer 70.

[0038] Then, after exposing the external terminals E1 and E2 by grinding the surface S1 which is the mounting surface, and forming a laminated film of nickel (Ni) and tin (Sn) on the surfaces of the external terminals E1 and E2 by electrolytic plating, the coil component 1 according to the present embodiment is completed.

[0039] Thus, in this embodiment, since the external terminals E1 and E2 are formed by coating, it is not necessary to perform soft etching on the magnetic element 10. Further, since the surface of the magnetic element 10 is covered with the protective insulating layer 70, plating does not adhere to unnecessary portions in the process of plating the surfaces of the external terminals E1 and E2.

[0040] FIG. 7 is a schematic perspective view showing the appearance of the coil component 2 according to the modified example.

[0041] The coil component 2 shown in FIG. 7 is different from the coil component 1 according to the above embodiment in that the external terminals E1 and E2 are provided over the entire width in the z direction of the surface S1. As illustrated by the coil component 2 according to the modified example, providing the external terminals E1 and E2 over the entire width in the z direction of the surface S1 can increase the mounting strength when mounted on a circuit board using solder or the like.

[0042] As described above, the preferred embodiments of the present invention have been described. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention, and it goes without saying that those are also included in the scope of the present invention.

[0043] For example, in the above embodiment, the case where the coil part 20 includes four conductor layers 31 to 34 has been described as an example. However, in the present invention, the number of conductor layers is not limited to this. Further, the number of turns of the coil conductor pattern formed in each conductor layer is not particularly limited either.

Explanation of Reference Numerals

[0044] 1, 2 Coil components 10 Magnetic element 11 to 14 Magnetic layers 20 Coil part 31 to 34 Conductor layers 40 to 44 Interlayer insulating layers 51 to 54, 61 to 64 Electrode patterns 70 Protective insulating layer C1 - C4 coil conductor patterns E1, E2 external terminals S support substrate S1 surface of the coil component V1 - V6 via conductors

Claims

1. A magnetic element comprising a composite member made of a resin containing conductive magnetic powder, a coil part in which a plurality of conductor layers including a coil conductor pattern embedded in the magnetic element and first and second electrode patterns exposed from the magnetic element, and a plurality of interlayer insulating layers are alternately laminated, a first external terminal provided on the first electrode pattern, a second external terminal provided on the second electrode pattern, and a protective insulating layer covering the magnetic element so that the first and second external terminals are exposed, wherein the protective insulating layer has a mounting surface, the first and second external terminals are exposed from the mounting surface without being exposed from another surface different from the mounting surface, the surfaces of the first and second external terminals and the surface of the protective insulating layer located around the first and second external terminals constitute the same plane, and the mounting surface has a recess between the first external terminal and the second external terminal, characterized in that it is a coil component.

2. The coil component according to claim 1, wherein the protective insulating layer covers the entire surface of the magnetic element.

3. The surface of the magnetic element has irregularities due to the protruding or falling conductive magnetic powder, and the protective insulating layer is provided so as to fill the irregularities, characterized in that it is the coil component according to claim 1 or 2.

4. The coil component according to any one of claims 1 to 3, wherein the first and second external terminals are made of a conductive paste.

5. The coil component according to any one of claims 1 to 4, wherein the first and second external terminals are exposed on a surface perpendicular to the lamination direction of the conductor layer and the interlayer insulating layer, and are provided over the entire width in the lamination direction.

6. A step of forming a coil layer by alternately laminating a coil conductor pattern and a plurality of conductor layers including first and second electrode patterns and a plurality of interlayer insulating layers, a step of embedding the coil layer with a magnetic element made of a composite member made of a resin containing conductive magnetic powder, a step of exposing the first and second electrode patterns by singulating or grinding the magnetic element, a step of applying first and second external terminals on the first and second electrode patterns respectively, and a step of covering the surfaces of the magnetic element and the first and second external terminals with a protective insulating layer, A step of exposing the first and second external terminals from the mounting surface by grinding the protective insulating layer without exposing the first and second external terminals from another surface different from the mounting surface of the protective insulating layer. In the step of covering with the protective insulating layer, a recess is formed in a portion located between the first external terminal and the second external terminal on the mounting surface. In the step of exposing the first and second external terminals, the protective insulating layer is ground so that the surfaces of the first and second external terminals and the surfaces of the protective insulating layer located around the first and second external terminals form the same plane. A method for manufacturing a coil component, characterized by this.

Images