Coil component

Abstract

To prevent a void from being formed in a magnetic element of a coil component which has a coil part embedded in the magnetic element.SOLUTION: A coil component 1 comprises a coil part 2, a magnetic layer M1 covering the coil part 2 from a coil axial direction, and a magnetic layer M2 located in an inner-diameter region of the coil part 2. The magnetic layer M1 and magnetic layer M2 are in contact with each other across an opening part 90A provided to an inter-layer insulation film 90 included in the coil part 2. The opening part 90A is so shaped as to increase in diameter with the distance from the boundary surface between the magnetic layer M1 and magnetic layer M2. Consequently, a void is hardly formed in the magnetic layer M1 embedded in the opening part 90A.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 is embedded in a magnetic base body, and a manufacturing method thereof. [Background technology]

[0002] Patent Document 1 discloses a coil component having a structure in which a coil portion is embedded in a magnetic base body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-11185 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the structure disclosed in Patent Document 1 has a problem in that voids are likely to occur at the interface between the first magnetic layer that covers the coil portion in the axial direction of the coil and the second magnetic layer that is embedded in the inner diameter region of the coil portion in the magnetic body. This problem becomes particularly pronounced when the first magnetic layer that covers the coil portion in the axial direction of the coil and the second magnetic layer that is embedded in the inner diameter region of the coil portion in the magnetic body are formed in separate processes.

[0005] Therefore, an object of the present invention is to prevent voids from occurring in a magnetic body in a coil component having a structure in which a coil portion is embedded in a magnetic body. [Means for solving the problem]

[0006] The coil component according to the present invention comprises a coil section having a structure in which a plurality of conductor layers, each having a coil pattern, are stacked in the coil axis direction with a plurality of interlayer insulating films interposed therebetween, a first magnetic layer covering the coil section in the coil axis direction, and a second magnetic layer located in the inner diameter region of the coil section, wherein the plurality of interlayer insulating films include a first interlayer insulating film closest to the first magnetic layer, the first magnetic layer and the second magnetic layer are in contact with each other through an opening provided in the first interlayer insulating film, and the opening has a shape whose diameter increases with increasing distance from the interface between the first magnetic layer and the second magnetic layer.

[0007] According to the present invention, voids are less likely to occur in the first magnetic layer filled in the opening, and magnetic flux passes through more easily, thereby increasing inductance.

[0008] In the present invention, the plurality of interlayer insulating films further includes a plurality of second interlayer insulating films different from the first interlayer insulating film, and the thickness of the first interlayer insulating film may be thicker than the thickness of the second interlayer insulating film. If the thickness of the first interlayer insulating film is thick, voids are likely to occur in the opening, but even in such a case, it is possible to prevent the occurrence of voids.

[0009] The coil component according to the present invention further includes first and second terminal electrodes, and the plurality of conductor layers may include a first conductor layer closest to the first magnetic layer, and the first conductor layer may include a conductor pattern connected to the first terminal electrode and a conductor pattern connected to the second terminal electrode. If the first conductor layer includes conductor patterns to which different potentials are applied, a short circuit may occur via the first magnetic layer. However, by ensuring a sufficient thickness of the first interlayer insulating film, it is possible to prevent such a short circuit.

[0010] In the present invention, the average particle size of the filler contained in the first interlayer insulating film may be smaller than the average particle size of the filler contained in the second interlayer insulating film, which makes the cross section of the opening flatter and therefore less likely to produce voids.

[0011] In the present invention, the diameter of the opening at the interface may be larger than the diameter of the second magnetic layer, which increases the volume of the first magnetic layer and therefore makes it possible to further increase the inductance.

[0012] A method for manufacturing a coil component according to the present invention comprises a first step of forming convex portions and concave portions in a metal foil provided on the surface of a substrate; a second step of forming a first interlayer insulating film having thin portions to which the shape of the convex portions is transferred and thick portions to which the shape of the concave portions is transferred by covering the surface of the metal foil with an insulating member; a third step of alternately stacking, on the first interlayer insulating film, a plurality of conductor layers having a coil pattern whose inner diameter region overlaps the thin portions and a plurality of second interlayer insulating films; a fourth step of embedding a second magnetic layer in the inner diameter region of the coil pattern; a fifth step of removing the metal foil to expose the first interlayer insulating film; a sixth step of removing the thin portions so as to expose the second magnetic layer; and a seventh step of forming a first magnetic layer covering the first interlayer insulating film so as to be in contact with the second magnetic layer, wherein the convex portions and concave portions are formed in the first step so that the width of the convex portions decreases with increasing distance from the bottom surface of the concave portion.

[0013] According to the present invention, it is possible to form a first interlayer insulating film having an opening whose diameter increases with increasing distance from the interface between the first and second magnetic layers, which makes it difficult for voids to form in the first magnetic layer that fills the opening when the first magnetic layer is formed.

[0014] In the present invention, the first step may be performed by forming recesses in the metal foil by etching. By adjusting the etching conditions, it is possible to obtain a structure in which the width of the protrusions decreases with increasing distance from the bottom of the recesses. In this case, a step of increasing the film thickness of the metal foil by plating may be further included before performing the first step. This allows the film thickness of the first interlayer insulating film to be further increased. [Effects of the Invention]

[0015] Thus, according to the present invention, in a coil component having a structure in which a coil portion is embedded in a magnetic body, it is possible to prevent voids from occurring in the magnetic body. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic perspective view illustrating the structure of a coil component 1 according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view taken along the line AA shown in FIG. [Figure 3] FIG. 3 is a schematic plan view illustrating the pattern shapes of the conductor layers L1, L3, L5, and L7 as viewed from the magnetic layer M1 side. [Figure 4] FIG. 4 is a schematic plan view illustrating the pattern shapes of the conductor layers L2, L4, L6, and L8 as viewed from the magnetic layer M1 side. [Figure 5] FIG. 5 is an equivalent circuit diagram of the coil device 1. As shown in FIG. [Figure 6] FIG. 6 is a partially enlarged view of the coil device 1. As shown in FIG. [Figure 7] FIG. 7 is a partially enlarged view of the coil device 1 according to the first modified example. [Figure 8] FIG. 8 is a partially enlarged view of the coil device 1 according to the second modified example. [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 diagram illustrating a method for manufacturing the coil device 1. [Figure 18] FIG. 18 is a process diagram illustrating a method for manufacturing the coil device 1. [Figure 19] FIG. 19 is a process diagram illustrating a method for manufacturing the coil device 1. [Figure 20] FIG. 20 is a process diagram illustrating a method for manufacturing the coil device 1. [Figure 21] FIG. 21 is a process diagram illustrating a method for manufacturing the coil device 1. 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 illustrating the structure of a coil component 1 according to one embodiment of the present invention, and Fig. 2 is a schematic cross-sectional view taken along line AA shown in Fig. 1.

[0019] The coil component 1 according to this embodiment is a surface-mount type balun transformer, and as shown in FIGS. 1 and 2, has a structure in which a coil portion 2 is embedded in a magnetic body M. The coil portion 2 is made up of interlayer insulating films 90-98 and conductor layers L1-L8 alternately stacked in the coil axis direction. The magnetic 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. Terminal electrodes E1-E4 are exposed from the magnetic layer M4.

[0020] The interlayer insulating film 90 is closest to the magnetic layer M1 and is in contact with the magnetic layer M1. Meanwhile, the interlayer insulating film 98 is closest to the magnetic layer M4 and is in contact with the magnetic layer M4. The interlayer insulating films 91 to 98 cover the conductor layers L1 to L8, respectively. The thickness T0 of the interlayer insulating film 90 is thicker than the thicknesses of the other interlayer insulating films 91 to 98. Therefore, when the thickness of the interlayer insulating film 98 is T8, T0 > T8. Here, the thickness T8 of the interlayer insulating film 98 is defined by the film thickness at the position where the conductor layer L8 is provided. The same applies to the thicknesses of the other interlayer insulating films 91 to 97, and they may be the same thickness as the thickness T8. The thickness T8 is, for example, 10 μm. In this case, the thickness T0 is greater than 10 μm, for example, approximately 15 to 20 μm.

[0021] The interlayer insulating films 90 to 98 have openings in portions that overlap with the inner diameter region of the coil part 2. Here, a magnetic layer M1 is provided in the opening of the interlayer insulating film 90, and a magnetic layer M2 is provided in the opening of the interlayer insulating films 91 to 98. As a result, the magnetic layer M1 and the magnetic layer M2 come into contact with each other through the openings provided in the interlayer insulating film 90. Each of the interlayer insulating films 90 to 98 has a protruding portion that protrudes toward the inner diameter region of the coil part 2.

[0022] The conductor layers L1 to L8 respectively have coil patterns 10, 20, 30, 40, 50, 60, 70, and 80. The magnetic body M is a composite 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, 40, 50, 60, 70, and 80. As the resin binder, it is preferable to use a liquid or powdered epoxy resin.

[0023] The terminal electrodes E1 and E2 are used, for example, as primary side terminals (unbalanced signal terminals), and the terminal electrodes E3 and E4 are used, for example, as secondary side terminals (balanced signal terminals). In this case, one of the terminal electrodes E1 and E2 constituting the unbalanced signal terminals is connected to an unbalanced transmission line, and the other is connected to a ground wiring. The terminal electrodes E3 and E4 are connected to a pair of balanced transmission lines.

[0024] Coil patterns 10, 30, 50, and 70 arranged on conductor layers L1, L3, L5, and L7 are connected between terminal electrode E1 and terminal electrode E2. Coil patterns 20, 40, 60, and 80 arranged on conductor layers L2, L4, L6, and L8 are connected between terminal electrode E3 and terminal electrode E4.

[0025] FIG. 3 is a schematic plan view illustrating the pattern shapes of the conductor layers L1, L3, L5, and L7 as viewed from the magnetic layer M1 side.

[0026] As shown in FIG. 3, the conductor layer L1 is provided with terminal patterns 11-14 in addition to the coil pattern 10, the conductor layer L3 is provided with terminal patterns 31-34 in addition to the coil pattern 30, the conductor layer L5 is provided with terminal patterns 51-54 in addition to the coil pattern 50, and the conductor layer L7 is provided with terminal patterns 71-74 in addition to the coil pattern 70. The terminal patterns 11, 31, 51, and 71 are short-circuited with each other, the terminal patterns 12, 32, 52, and 72 are short-circuited with each other, the terminal patterns 13, 33, 53, and 73 are short-circuited with each other, and the terminal patterns 14, 34, 54, and 74 are short-circuited with each other. The outer peripheral ends of the coil patterns 10 and 30 included in the conductor layers L1 and L3 are connected to the terminal patterns 11 and 31, respectively. The outer peripheral ends of the coil patterns 50 and 70 included in the conductor layers L5 and L7 are connected to the terminal patterns 52 and 72, respectively. Furthermore, the inner peripheral ends of the coil patterns 10, 30, 50, and 70 included in the conductor layers L1, L3, L5, and L7 are short-circuited to each other.

[0027] The coil patterns 10 and 30 are wound counterclockwise (left-handed) from the outer peripheral edge toward the inner peripheral edge, and the coil patterns 50 and 70 are wound clockwise (right-handed) from the outer peripheral edge toward the inner peripheral edge. The relay patterns 35, 55, and 75 included in the conductor layers L3, L5, and L7 are independent of the coil patterns 30, 50, and 70, and are connected to the inner peripheral edges of the coil patterns 20, 40, 60, and 80, which will be described later. The dummy pattern 15 provided on the conductor layer L1 is provided to prevent steps in this area on the upper conductor layers L2 to L8.

[0028] FIG. 4 is a schematic plan view illustrating the pattern shapes of the conductor layers L2, L4, L6, and L8 as viewed from the magnetic layer M1 side.

[0029] As shown in FIG. 4, the conductor layer L2 is provided with terminal patterns 21-24 in addition to the coil pattern 20, the conductor layer L4 is provided with terminal patterns 41-44 in addition to the coil pattern 40, the conductor layer L6 is provided with terminal patterns 61-64 in addition to the coil pattern 60, and the conductor layer L8 is provided with terminal patterns 81-84 in addition to the coil pattern 80. The terminal patterns 81-84 are connected to the terminal electrodes E1-E4, respectively, through via conductors provided in the interlayer insulating film 98. The terminal patterns 21, 41, 61, and 81 are short-circuited with each other, the terminal patterns 22, 42, 62, and 82 are short-circuited with each other, the terminal patterns 23, 43, 63, and 83 are short-circuited with each other, and the terminal patterns 24, 44, 64, and 84 are short-circuited with each other. The outer peripheral ends of the coil patterns 20 and 40 included in the conductor layers L2 and L4 are connected to the terminal patterns 23 and 43, respectively. Furthermore, the outer peripheral ends of the coil patterns 60, 80 included in the conductor layers L6, L8 are connected to the respective terminal patterns 64, 84. Furthermore, the inner peripheral ends of the coil patterns 20, 40, 60, 80 included in the conductor layers L2, L4, L6, L8 are short-circuited to each other.

[0030] The coil patterns 20 and 40 are wound clockwise (right-handed) from the outer peripheral edge to the inner peripheral edge, and the coil patterns 60 and 80 are wound counterclockwise (left-handed) from the outer peripheral edge to the inner peripheral edge. The relay patterns 25, 45, and 65 included in the conductor layers L2, L4, and L6 are independent of the coil patterns 20, 40, and 60, and are connected to the inner peripheral edges of the coil patterns 10, 30, 50, and 70.

[0031] Terminal patterns 11, 21, 31, 41, 51, 61, 71, and 81 are provided at positions overlapping with terminal electrode E1 in a plan view and are connected to each other via via conductors provided to penetrate the interlayer insulating films 91 to 97. Terminal patterns 12, 22, 32, 42, 52, 62, 72, and 82 are provided at positions overlapping with terminal electrode E2 in a plan view and are connected to each other via via conductors provided to penetrate the interlayer insulating films 91 to 97. Terminal patterns 13, 23, 33, 43, 53, 63, 73, and 83 are provided at positions overlapping with terminal electrode E3 in a plan view and are connected to each other via via conductors provided to penetrate the interlayer insulating films 92 to 97. Terminal patterns 14, 24, 34, 44, 54, 64, 74, and 84 are provided at positions overlapping with terminal electrode E4 in a plan view and are connected to each other via via conductors provided to penetrate the interlayer insulating films 92 to 97. The side surfaces of the terminal patterns are exposed from the interlayer insulating films 91 to 98, and are covered with barrel plating layers P1 to P4, respectively, in the same manner as the surfaces of the terminal electrodes E1 to E4.

[0032] The coil device 1 according to this embodiment has the coil patterns 10, 30, 50, and 70 and the coil patterns 20, 40, 60, and 80, each having the above-described structure, stacked alternately and coaxially. Therefore, as shown in the equivalent circuit diagram of FIG. 5, the parallel-connected coil patterns 10 and 30 and the parallel-connected coil patterns 50 and 70 are connected in series between the terminal electrodes E1 and E2, and the parallel-connected coil patterns 20 and 40 and the parallel-connected coil patterns 60 and 80 are connected in series between the terminal electrodes E3 and E4. Since each of the coil patterns 10, 30, 50, and 70 has 4.5 turns, a total of nine turns of coil are connected between the terminal electrodes E1 and E2. Similarly, since each of the coil patterns 20, 40, 60, and 80 has 4.5 turns, a total of nine turns of coil are connected between the terminal electrodes E3 and E4.

[0033] As described above, in the coil component 1 according to this embodiment, the parallel-connected coil patterns 10, 30 and the parallel-connected coil patterns 20, 40 are coaxially stacked in this order, and the parallel-connected coil patterns 50, 70 and the parallel-connected coil patterns 60, 80 are coaxially stacked in this order, which enables to enhance the magnetic coupling between the coil patterns 10, 30, 50, 70 constituting the primary winding and the coil patterns 20, 40, 60, 70 constituting the secondary winding. Moreover, since the terminal electrodes E1 to E4 are all connected to the outer peripheral ends of the corresponding coil patterns, it is easy to connect the coil patterns to the terminal electrodes E1 to E4.

[0034] In this embodiment, the cross section of the opening provided in the interlayer insulating film 90 has a tapered shape. More specifically, as shown in the enlarged view of Fig. 6, the opening 90A provided in the interlayer insulating film 90 has a diameter W2 on the lower surface 90C side opposite the upper surface 90B, which is larger than a diameter W1 on the upper surface 90B side where the conductor layer L1 is formed, and the inner wall 90D has a tapered shape. This shape makes it difficult for voids to be generated in the magnetic layer M1 in the manufacturing process described below, and also makes it easier for magnetic flux to pass through the inner wall 90D than when the inner wall 90D is vertical, thereby increasing inductance.

[0035] However, the inner wall 90D of the opening 90A does not necessarily have to be tapered; it is sufficient that the diameter of the opening 90A increases with increasing distance from the interface between the magnetic layers M1 and M2. Therefore, as shown in FIG. 7 (a first modification), the inner wall 90D of the opening 90A may be curved. This makes the inner wall 90D of the opening 90A near the interface between the magnetic layers M1 and M2 more horizontal, making it less likely that voids will form in the magnetic layer M1. Furthermore, as shown in FIG. 8 (a second modification), the diameter W1 of the top surface 90B located at the interface between the magnetic layers M1 and M2 may be larger than the diameter of the magnetic layer M2. This increases the volume of the magnetic layer M1, thereby further improving inductance.

[0036] Next, a method for manufacturing the coil component 1 according to this embodiment will be described.

[0037] 9 to 21 are process diagrams illustrating a method for manufacturing the coil component 1 according to this embodiment. The process diagrams shown in Fig. 9 to 21 show a cross section corresponding to one coil component 1, but in reality, a large number of coil components 1 can be obtained by simultaneously manufacturing many coil components 1 using an aggregate substrate.

[0038] First, a support 100 is prepared, with metal foils 102 and 103 made of copper (Cu) or the like provided on the surface of a base material 101 (FIG. 9). A release layer is provided at the interface between the metal foils 102 and 103. The thickness of the metal foil 102 is, for example, 3 μm, and the thickness of the metal foil 103 is, for example, 18 μm. Next, a metal foil 104 made of copper (Cu) or the like is formed on the metal foil 103 by electrolytic plating, thereby increasing the total film thickness of the metal foils 102 to 104 (FIG. 10). The thickness of the metal foil 104 is, for example, 20 μm.

[0039] Next, a resist pattern R1 is formed on the surface of the metal foil 104, and then the metal foil 104 is etched using the resist pattern R1 as a mask until it reaches the metal foil 103 (FIG. 11). The etching amount is preferably slightly greater than the thickness of the metal foil 104; if the thickness of the metal foil 104 is 20 μm, the etching amount can be approximately 24 μm. As a result, convex portions 105 and concave portions 106 are formed on the metal foils 103 and 104. The etching is performed under conditions such that the width of the convex portions 105 decreases with increasing distance from the bottom of the concave portions 106. As a result, the width of the convex portions 105 becomes W1 at the upper portions in contact with the resist pattern R1 and W2 (>W1) at the lower portions at the bottom of the concave portions 106.

[0040] Next, after removing the resist pattern R1, the surfaces of the metal foils 103 and 104 are covered with an insulating material by lamination to form the interlayer insulating film 90 (FIG. 12). As a result, the shapes of the convex portions 105 and the concave portions 106 are transferred to the interlayer insulating film 90, and the interlayer insulating film 90 is formed with a thin portion 90E to which the shape of the convex portions 105 is transferred and a thick portion 90F to which the shape of the concave portions 106 is transferred. Here, by using a filler with a small particle size as the filler contained in the interlayer insulating film 90, the inner wall 90D of the opening 90A can be made flatter. For this reason, the average particle size of the filler contained in the interlayer insulating film 90 may be smaller than the average particle size of the fillers contained in the interlayer insulating films 91 to 98. Thereafter, a seed layer S1 is formed on the surface of the interlayer insulating film 90 by electroless plating.

[0041] Next, a resist pattern R2 is formed on the surface of the seed layer S1 (FIG. 13). The resist pattern R2 is a negative pattern of the conductor layer L1. In this state, the seed layer S1 is grown by electrolytic plating to form the conductor layer L1 (FIG. 14). At this time, a sacrificial pattern SP1 is formed in the inner diameter region and outer diameter region of the coil pattern 10. The sacrificial pattern SP1 is formed in a position overlapping the thin portion 90E of the interlayer insulating film 90 in a planar view. In contrast, the coil pattern 10 is formed in a position overlapping the thick portion 90F of the interlayer insulating film 90. Therefore, the inner diameter region of the coil pattern 10 overlaps the thin portion 90E of the interlayer insulating film 90. Then, after peeling off the resist pattern R2, the seed layer S1 exposed in the peeled portion of the resist pattern R2 is removed by etching, thereby completing the conductor layer L1 (FIG. 15).

[0042] Next, an interlayer insulating film 91 is formed to bury the conductor layer L1, and then vias are formed in the locations where via conductors should be formed (FIG. 16). A seed layer S2 is then formed on the surface of the interlayer insulating film 91 by electroless plating. The steps shown in FIGS. 13 to 16 are repeated to alternately form conductor layers L2 to L8 and interlayer insulating films 92 to 98 (FIG. 17). This completes the coil portion 2. Next, vias are formed in the interlayer insulating film 98 to expose the terminal patterns 81 to 84, and then the terminal electrodes E1 to E4 are formed (FIG. 18). Then, wet etching is performed with the external terminals E1 to E4 covered with a resist pattern (not shown) to remove the sacrificial patterns SP1 to SP8. The conductor patterns constituting the coil portion 2 are not etched because they are covered with the interlayer insulating films 90 to 98. This leaves spaces S in the inner diameter region and outer diameter region of the coil portion 2. The external terminals E1 to E4 may be formed after removing the sacrificial patterns SP1 to SP8.

[0043] Next, magnetic elements M2 to M4 are formed to fill this space S (FIG. 19). Next, the support 100 is removed by peeling the interface between the metal foil 102 and the metal foil 103, and then the metal foils 103 and 104 are removed by etching (FIG. 20). This exposes the uneven surface of the interlayer insulating film 90. In this state, an ashing process is performed to reduce the overall thickness of the interlayer insulating film 90 (FIG. 21). The amount of reduction in thickness is adjusted so that the thin portion 90E is removed to expose the magnetic layer M2, and the thick portion 90F remains. The portion from which the thin portion 90E is removed becomes an opening 90A, and its inner wall 90D is tapered.

[0044] Next, the magnetic layer M1 is formed to cover the interlayer insulating film 90 (FIG. 2). The magnetic layer M1 is also formed inside the opening 90A, thereby bringing the magnetic layer M1 and the magnetic layer M2 into contact. At this time, if the inner wall 90D of the opening 90A is vertical, voids are likely to occur at the corners. However, in this embodiment, the inner wall 90D of the opening 90A is tapered, making such voids less likely to occur. In particular, if a filler with a small particle size is used as the filler contained in the interlayer insulating film 90, the inner wall 90D of the opening 90A becomes flatter, making it more unlikely for voids to occur. After the substrate is diced into individual pieces, barrel plating layers P1 to P4 are formed on the surfaces of the terminal electrodes E1 to E4 by barrel plating, completing the coil component 1 according to this embodiment.

[0045] As described above, in this embodiment, the metal foils 103 and 104 are etched so that the width of the protrusion 105 satisfies W2 > W1, and this shape is transferred to the interlayer insulating film 90. This allows the inner wall 90D of the opening 90A to be tapered, thereby preventing voids from occurring in the magnetic layer M1. Furthermore, in this embodiment, the metal foil 104 is laminated on the metal foil 103 by electroplating, ensuring a sufficient thickness T0 of the remaining interlayer insulating film 90. This also prevents short-circuiting through the magnetic layer M1 between the coil pattern 10 or terminal patterns 11 and 12 on the primary side and the terminal patterns 13 and 14 on the secondary side. Meanwhile, short-circuiting through the magnetic layer M4 between the terminal patterns 81 and 82 on the primary side and the coil pattern 80 or terminal patterns 83 and 84 on the secondary side can be prevented by ensuring a sufficient thickness of the interlayer insulating film 98 covering the conductor layer L8.

[0046] 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.

[0047] For example, although the coil component 1 according to the above embodiment has eight conductor layers L1 to L8, the number of conductor layers is not limited to this. Also, it is not essential to connect two coil patterns located on different conductor layers in parallel. Furthermore, the use of the coil component according to the present invention is not limited to balun transformers, and any use is possible as long as the coil component has multiple electrically insulated coil patterns. [Explanation of symbols]

[0048] 1 Coil parts 2 Coil section 10, 20, 30, 40, 50, 60, 70, 80 coil patterns 11~14, 21~24, 31~34, 41~44, 51~54, 61~64, 71~74, 81~84 Terminal pattern 15 Dummy Pattern 25,35,45,55,65,75 relay pattern 90~98 Interlayer insulating film 90A opening 90B top surface 90C Bottom 90D inner wall 90E Thin section 90F thick part 100 support 101 Base material 102~104 Metal foil 105 Convex part 106 Recess E1~E4 terminal electrode L1~L8 conductor layers M magnetic element M1~M4 Magnetic layer P1~P4 Barrel plating layer R1,R2 resist pattern S space S1, S2 seed layer SP1~SP8 Sacrifice Pattern

Claims

1. a coil portion having a structure in which a plurality of conductor layers, each having a coil pattern, are stacked in a coil axis direction via a plurality of interlayer insulating films; a first magnetic layer that covers the coil portion in the coil axis direction; a second magnetic layer located in an inner diameter region of the coil portion, the plurality of interlayer insulating films include a first interlayer insulating film closest to the first magnetic layer and a plurality of second interlayer insulating films different from the first interlayer insulating film; the first magnetic layer and the second magnetic layer are in contact with each other through an opening provided in the first interlayer insulating film; the opening has a shape whose diameter increases with increasing distance from the interface between the first magnetic layer and the second magnetic layer, the first interlayer insulating film has a thickness greater than the thickness of the second interlayer insulating film; A coil component, wherein the average particle size of the filler contained in the first interlayer insulating film is smaller than the average particle size of the filler contained in the second interlayer insulating film.

2. Further comprising first and second terminal electrodes; the plurality of conductor layers includes a first conductor layer closest to the first magnetic layer, 2. The coil component according to claim 1, wherein the first conductor layer includes a conductor pattern connected to the first terminal electrode and a conductor pattern connected to the second terminal electrode.

3. 3. The coil component according to claim 1, wherein the diameter of the opening at the interface is larger than the diameter of the second magnetic layer.

4. a coil portion having a structure in which a plurality of interlayer insulating films and a plurality of conductor layers are alternately stacked in the coil axis direction; a first magnetic layer that covers the coil portion in the coil axis direction; a second magnetic layer located in an inner diameter region of the coil portion, the plurality of interlayer insulating films include a first interlayer insulating film closest to the first magnetic layer and a plurality of second interlayer insulating films different from the first interlayer insulating film; the first interlayer insulating film has a thickness greater than the thickness of the second interlayer insulating film; the first magnetic layer and the second magnetic layer are in contact with each other through an opening provided in the first interlayer insulating film; the opening has a shape whose diameter increases with increasing distance from the interface between the first magnetic layer and the second magnetic layer, the plurality of conductor layers includes a first conductor layer closest to the first magnetic layer, The coil component is characterized in that the first conductor layer includes a coil pattern belonging to a primary side and a terminal pattern belonging to a secondary side.

5. 5. The coil component according to claim 4, wherein the average particle size of the filler contained in the first interlayer insulating film is smaller than the average particle size of the filler contained in the second interlayer insulating film.

6. 6. The coil component according to claim 4, wherein the diameter of the opening at the interface is larger than the diameter of the second magnetic layer.

Images