Coil component and manufacturing method therefor

Abstract

A coil component is provided with a coil part in which a plurality of conductor layers and a plurality of interlayer insulating layers are alternately laminated; and a sealing resin layer that covers the coil part. The conductor layers each include a spiral pattern. The interlayer insulating layers each cover an upper surface and a side surface of the spiral pattern. The recessed part is formed in the side wall surface of the interlayer insulating layer. A part of the sealing resin layer is embedded in the recessed part.

Claims

1. A coil component comprising: a coil part in which a plurality of conductor layers and a plurality of interlayer insulating layers are alternately laminated; and a sealing resin layer that covers the coil part, wherein the conductor layers each include a spiral pattern, the interlayer insulating layers each cover an upper surface and a side surface of the spiral pattern, a recessed part is formed in a side wall surface of the interlayer insulating layer, and a part of the sealing resin layer is embedded in the recessed part, at least one of the plurality of conductor layers further includes at least one auxiliary pattern connected to an innermost turn or an outermost turn of the spiral pattern, the interlayer insulating layer covers the upper and side surfaces of the spiral pattern and also covers an upper surface of the auxiliary pattern, and the recessed part is formed at a position from which a side surface of the auxiliary pattern is exposed.

2. The coil component as claimed in claim 1, wherein the sealing resin layer is a magnetic resin layer containing metal magnetic particles and resin binder, and the resin binder is embedded in the recessed part while preventing the metal magnetic particles from being embedded in the recessed part.

3. The coil component as claimed in claim 1, wherein the auxiliary pattern includes an inner auxiliary pattern connected to the innermost turn of the spiral pattern.

4. The coil component as claimed in claim 3, wherein the auxiliary pattern further includes an outer auxiliary pattern connected to the outermost turn of the spiral pattern.

5. The coil component as claimed in claim 4, wherein the coil part has three or more conductor layers, and both the inner auxiliary pattern and the outer auxiliary pattern are provided in an intermediate conductor layer between the lowermost and uppermost layers.

6. The coil component as claimed in claim 5, wherein the lowermost and uppermost conductor layers of the plurality of conductor layers have the inner auxiliary pattern and do not have the outer auxiliary pattern.

7. The coil component as claimed in claim 4, wherein the coil part is formed by alternately laminating first to fourth conductor layers and first to fourth interlayer insulting layers, the first and fourth conductor layers each include the spiral pattern and the inner auxiliary pattern, and the second and third conductor layers each include the spiral pattern, the inner auxiliary pattern and the outer auxiliary pattern.

8. The coil component as claimed in claim 1, wherein the auxiliary pattern has a bend.

9. The coil component as claimed in claim 1, wherein the plurality of conductor layers each have a seed layer and a plating layer formed on the seed layer by electrolytic plating, each spiral pattern is constituted by the seed layer and the plating layer, and the auxiliary pattern is constituted by the seed layer.

10. The coil component as claimed in claim 1, wherein the height of the recessed part is 1 μm to 10 μm.

11. The coil component as claimed in claim 1, wherein the depth of the recessed part is 3 mm to 25 mm.

12. A coil component comprising: a first spiral conductive pattern including a plurality of turns having an innermost turn, each of the turns having a lower surface, an upper surface, an inner side surface, and an outer side surface; a first insulating layer covering the lower surface of the first spiral conductive pattern; and a second insulating layer covering the upper surface, the inner side surface, and the outer side surface of the first spiral conductive pattern, a second spiral conductive pattern including a plurality of turns having innermost and outermost turns, each of the turns having a lower surface covered with the second insulating layer, an upper surface, an inner side surface, and an outer side surface; and a third insulating layer covering the upper surface, the inner side surface, and the outer side surface of the second spiral conductive pattern, wherein the second insulating layer includes a first inner wall covering the inner side surface of the innermost turn, wherein the first inner wall of the second insulating layer includes a first opening that exposes a part of the inner side surface of the innermost turn, wherein the third insulating layer includes a second inner wall covering the inner side surface of the innermost turn of the second spiral conductive pattern, wherein the second inner wall of the third insulating layer includes a third opening that exposes a part of the inner side surface of the innermost turn of the second spiral conductive pattern, wherein the third insulating layer further includes an outer wall covering the outer side surface of the outermost turn of the second spiral conductive pattern, and wherein the outer wall of the third insulating layer includes a fourth opening that exposes a part of the outer side surface of the outermost turn of the second spiral conductive pattern.

13. The coil component as claimed in claim 12, wherein the first inner wall of the second insulating layer further includes a second opening that exposes another part of the inner side surface of the innermost turn.

14. The coil component as claimed in claim 12, further comprising a magnetic resin layer embedded in an inner diameter area of the first spiral conductive pattern, wherein the magnetic resin layer comprises metal magnetic particles and resin binder, and wherein the resin binder is embedded in the first opening.

15. The coil component as claimed in claim 14, wherein the resin binder embedded in the first opening is in contact with the part of the inner side surface of the innermost turn.

16. The coil component as claimed in claim 14, wherein the metal magnetic particles are greater in size than the first opening.

17. The coil component as claimed in claim 12, wherein the part of the inner side surface of the innermost turn is located inside the first opening such that the part of the inner side surface of the innermost turn is arranged between the first insulating layer and the first inner wall of the second insulating layer.

18. A coil component comprising: a first spiral conductive pattern including a plurality of turns having an innermost turn, each of the turns having a lower surface, an upper surface, an inner side surface, and an outer side surface; a magnetic resin layer embedded in an inner diameter area of the first spiral conductive pattern; a first insulating layer covering the lower surface of the first spiral conductive pattern; and a second insulating layer covering the upper surface, the inner side surface, and the outer side surface of the first spiral conductive pattern, wherein the second insulating layer includes a first inner wall covering the inner side surface of the innermost turn, wherein the first inner wall of the second insulating layer includes a first opening that exposes a part of the inner side surface of the innermost turn, wherein the magnetic resin layer comprises metal magnetic particles and resin binder, wherein the resin binder is embedded in the first opening, and wherein the metal magnetic particles are greater in size than the first opening.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above and other objects, features and advantages of this invention will become more apparent by reference to the following detailed description of the invention taken in conjunction with the accompanying drawings:

(2) FIG. 1 is a perspective view illustrating the outer appearance of a coil component according to a preferred embodiment of the present invention;

(3) FIGS. 2A and 2B are each a cross-sectional side view illustrating the structure of the coil component 10 according to the present embodiment;

(4) FIGS. 3A to 3D are plan layout views of the conductor layers of the coil part 20 having a four-layer structure;

(5) FIGS. 4A to 4C are views for explaining the manufacturing method for the coil component 10, wherein FIG. 4A is a schematic plan view, FIG. 4B is a cross-sectional view taken along line X.sub.1-X.sub.1 in FIG. 4A, and FIG. 4C is a cross-sectional view taken along line X.sub.2-X.sub.2 in FIG. 4A;

(6) FIGS. 5A to 5C are views for explaining the manufacturing method for the coil component 10, wherein FIG. 5A is a schematic plan view, FIG. 5B is a cross-sectional view taken along line X.sub.1-X.sub.1 in FIG. 5A, and FIG. 5C is a cross-sectional view taken along line X.sub.2-X.sub.2 in FIG. 5A;

(7) FIGS. 6A to 6C are views for explaining the manufacturing method for the coil component 10, wherein FIG. 6A is a schematic plan view, FIG. 6B is a cross-sectional view taken along line X.sub.1-X.sub.1 in FIG. 6A, and FIG. 6C is a cross-sectional view taken along line X.sub.2-X.sub.2 in FIG. 6A;

(8) FIGS. 7A to 7C are views for explaining the manufacturing method for the coil component 10, wherein FIG. 7A is a schematic plan view, FIG. 7B is a cross-sectional view taken along line X.sub.1-X.sub.1 in FIG. 7A, and FIG. 7C is a cross-sectional view taken along line X.sub.2-X.sub.2 in FIG. 7A;

(9) FIGS. 8A to 8C are views for explaining the manufacturing method for the coil component 10, wherein FIG. 8A is a schematic plan view, FIG. 8B is a cross-sectional view taken along line X.sub.1-X.sub.1 in FIG. 8A, and FIG. 8C is a cross-sectional view taken along line X.sub.2-X.sub.2 in FIG. 8A;

(10) FIGS. 9A to 9C are views for explaining the manufacturing method for the coil component 10, wherein FIG. 9A is a schematic plan view, FIG. 9B is a cross-sectional view taken along line X.sub.1-X.sub.1 in FIG. 9A, and FIG. 9C is a cross-sectional view taken along line X.sub.2-X.sub.2 in FIG. 9A;

(11) FIGS. 10A to 10C are views for explaining the manufacturing method for the coil component 10, wherein FIG. 10A is a schematic plan view, FIG. 10B is a cross-sectional view taken along line X.sub.1-X.sub.1 in FIG. 10A, and FIG. 10C is a cross-sectional view taken along line X.sub.2-X.sub.2 in FIG. 10A;

(12) FIGS. 11A to 11C are views for explaining the manufacturing method for the coil component 10, wherein FIG. 11A is a schematic plan view, FIG. 11B is a cross-sectional view taken along line X.sub.1-X.sub.1 in FIG. 11A, and FIG. 11C is a cross-sectional view taken along line X.sub.2-X.sub.2 in FIG. 11A;

(13) FIGS. 12A to 12C are views for explaining the manufacturing method for the coil component 10, wherein FIG. 12A is a schematic plan view, FIG. 12B is a cross-sectional view taken along line X.sub.1-X.sub.1 in FIG. 12A, and FIG. 12C is a cross-sectional view taken along line X.sub.2-X.sub.2 in FIG. 12A;

(14) FIGS. 13A to 13C are views for explaining the manufacturing method for the coil component 10, wherein FIG. 13A is a schematic plan view, FIG. 13B is a cross-sectional view taken along line X.sub.1-X.sub.1 in FIG. 13A, and FIG. 13C is a cross-sectional view taken along line X.sub.2-X.sub.2 in FIG. 13A;

(15) FIGS. 14A and 14B are views for explaining the manufacturing method for the coil component 10, wherein FIG. 14A is a cross-sectional view corresponding to the position of line X.sub.1-X.sub.1 in FIG. 4A, etc., and FIG. 14B is a cross-sectional view corresponding to the position of line X.sub.2-X.sub.2 in FIG. 4A, etc.;

(16) FIGS. 15A and 15B are each a cross-sectional view corresponding to line X.sub.1-X.sub.1 in FIG. 4A, etc.;

(17) FIGS. 16A and 16B are each a cross-sectional view corresponding to line X.sub.1-X.sub.1 in FIG. 4A, etc.;

(18) FIGS. 17A and 17B are each a cross-sectional view corresponding to line X.sub.1-X.sub.1 in FIG. 4A, etc.; and

(19) FIG. 18 is a plan view illustrating a modification of the planar shape of the auxiliary pattern.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(20) Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

(21) FIG. 1 is a perspective view illustrating the outer appearance of a coil component according to a preferred embodiment of the present invention.

(22) A coil component 10 according to the present embodiment is a surface-mount type chip component suitably used as an inductor for a power supply circuit and has first and second magnetic resin layers 11 and 12 as illustrated in FIG. 1. A coil pattern to be described later is embedded in the first and second magnetic resin layers 11 and 12. One end of the coil pattern is connected to a first external terminal E1, and the other end thereof is connected to a second external terminal E2. The coil component according to the present embodiment may not necessarily be the surface-mount type chip component but may be a chip component of a type embedded in a circuit board.

(23) The first and second magnetic resin layers 11 and 12 are each a composite member made of resin containing metal magnetic particles and constitute a magnetic path for magnetic flux generated by making current flow in the coil pattern. As the metal magnetic particles, a permalloy-based material is preferably used. As the resin, semi-cured epoxy resin of liquid or powder is preferably used. The first and second magnetic resin layers 11 and 12 may be made of the same material or different materials. In the former case, material cost can be reduced.

(24) Unlike common laminated coil components, the coil component 10 according to the present embodiment is vertically mounted such that the z-direction that is the lamination direction is parallel to a circuit board. Specifically, a surface constituting the xz plane is used as a mounting surface S1. On the mounting surface S1, the first and second external terminals E1 and E2 are provided. The first external terminal E1 is continuously formed from the mounting surface S1 to a side surface S2 constituting the yz plane, and the second external terminal E2 is continuously formed from the mounting surface S1 to a side surface S3 constituting the yz plane.

(25) FIGS. 2A and 2B are each a cross-sectional side view illustrating the structure of the coil component 10 according to the present embodiment. FIG. 2A illustrates the entire structure, and FIG. 2B illustrates a part of the structure illustrated in FIG. 2A in an enlarged manner.

(26) As illustrated in FIGS. 2A and 2B, a coil part 20 is embedded inside the laminated body of the first and second magnetic resin layers 11 and 12. The coil part 20 has four conductor layers 40a to 40d having spiral patterns C1 to C4, respectively. Each of the spiral patterns C1 to C4 has about three turns. Thus, the total number of turns of the coil pattern C is about 12. The surfaces of the spiral patterns C1 to C4 of the conductor layers 40a to 40d are covered with an insulating gap layer 30 and interlayer insulating layers 50a to 50d, thus preventing the coil pattern C from contacting the first and second magnetic resin layers 11 and 12.

(27) The first magnetic resin layer 11 covers the coil part 20 from one side in the coil axis direction (z-direction) and is provided in an inner diameter area 22 surrounded by the coil part 20, an outer peripheral area 23 surrounding the coil part 20, and an upper area 24 on one side of the coil part 20 in the coil axis direction. On the other hand, the second magnetic resin layer 12 covers the coil part 20 from the other side in the coil axis direction (z-direction) and is provided in a lower area 21 on the other side of the coil part 20 in the coil axis direction.

(28) The insulating gap layer 30 (insulating resin layer) is provided between the first magnetic resin layer 11 and the second magnetic resin layer 12. The insulating gap layer 30 is made of a non-magnetic material such as resin and has a role of preventing magnetic saturation by forming a magnetic gap between the first magnetic resin layer 11 and the second magnetic resin layer 12. The first magnetic resin layer 11 is positioned on the side of a front surface 30a of the insulating gap layer 30, and the second magnetic resin layer 12 is positioned on the side of a back surface 30b thereof.

(29) As illustrated, the interlayer insulating layers 50a to 50d cover the upper and side surfaces of the spiral patterns C1 to C4, respectively, and also cover auxiliary patterns 42, and a recessed part 50x for exposing the side surface (end surface) of each of the auxiliary patterns 42 is formed in a side wall surface 50y of each of the interlayer insulating layers 50a to 50d. A height h of the recessed part 50x in the lamination direction of the coil part 20 is preferably 1 μm to 10 μm, and a depth d thereof is preferably 3 μm to 25 μm. The depth direction of the recessed part 50x refers to a direction perpendicular to the side wall surface 50y and parallel to the lamination surface of the coil part 20.

(30) A part of the magnetic resin layer 11, particularly, a part of resin binder constituting the first magnetic resin layer 11 enters and filled in the recessed part 50x. The magnetic resin layer 11 is made of resin containing the metal magnetic particles, and the diameter of each metal magnetic particle is larger than the height of the recessed part 50x. This prevents the metal magnetic particles from entering the recessed part 50x and allows only the resin binder of the magnetic resin layer 11 to enter the recessed part 50x. Thus, insulation performance of the coil pattern C can be secured.

(31) Although details will be described later, the auxiliary pattern 42 is used for securing a plating current path in an electrolytic plating process for the spiral patterns C1 to C4 and includes an inner auxiliary pattern 42a connected to the innermost turn of the spiral pattern and an outer auxiliary pattern 42b connected to the outermost turn of the spiral pattern. In the present embodiment, the inner auxiliary pattern 42a is connected to the innermost turn of each of the first to fourth spiral patterns C1 to C4 (first layer spiral pattern C1, second layer spiral pattern C2, third layer spiral pattern C3, fourth layer spiral pattern C4) and, thus, the recessed part 50x in the side wall surface on the inner peripheral side of each of the first to fourth interlayer insulating layers 50a to 50d is formed at a position from which the side surface of the inner auxiliary pattern 42a is exposed. The outer auxiliary pattern 42b is connected to the outermost turn of each of the second and third spiral patterns C2 and C3 and, thus, the recessed part 50x in the side wall surface on the outer peripheral side of each of the second and third interlayer insulating layers 50b and 50c is formed at a position from which the side surface of the outer auxiliary pattern 42b is exposed. The outer auxiliary pattern 42b is not connected to the outermost turn of each of the first and fourth spiral patterns C1 to C4 and, accordingly, the recessed part 50x for exposing the side surface of the outer auxiliary pattern 42b is not formed in the side wall surface on the outer peripheral side of each of the first and fourth interlayer insulating layers 50a and 50d.

(32) As described above, the recessed part 50x is formed in the side wall surface of each of the interlayer insulating layers 50a to 50d, and a part of the first magnetic resin layer 11 is embedded in the recessed part 50x, whereby anchor effect of the first magnetic resin layer 11 can be enhanced to thereby improve adhesion between the first magnetic resin layer 11 and the interlayer insulating layers 50a to 50d.

(33) FIGS. 3A to 3D are plan layout views of the conductor layers of the coil part 20 having a four-layer structure.

(34) As illustrated in FIGS. 3A to 3D, the outer peripheral end of the first spiral pattern C1 of the coil part 20 is connected to the first external terminal E1. The inner peripheral end of the first spiral pattern C1 is connected to the inner peripheral end of the second spiral pattern C2 through a through hole conductor 45a penetrating the interlayer insulating layer 50a. The outer peripheral end of the second spiral pattern C2 is connected to the outer peripheral end of the third spiral pattern C3 through a through hole conductor 45b penetrating the interlayer insulating layer 50b. The inner peripheral end of the third spiral pattern C3 is connected to the outer peripheral end of the fourth spiral pattern C4 through a through hole conductor 45c penetrating the interlayer insulating layer 50c. The outer peripheral end of the fourth spiral pattern C4 is connected to the second external terminal E2. The four spiral patterns C1 to C4 are thus connected in series to constitute a single coil element.

(35) The two small inner auxiliary patterns 42a protruding toward the center are formed inside the center portion in the y-direction of the innermost turn of each of the spiral patterns C1 to C4, and the two small outer auxiliary patterns 42b are formed outside the center portion in the y-direction of the outermost turn of each of the spiral patterns C2 and C3. As described above, the first (lowermost) and fourth (uppermost) spiral patterns C1 and C4 are connected only with the inner auxiliary pattern 42a and not connected with the outer auxiliary pattern 42b. On the other hand, the second and third (intermediate) spiral patterns C2 and C3 are connected with both the inner auxiliary pattern 42a and outer auxiliary pattern 42b. The inner auxiliary pattern 42a and outer auxiliary pattern 42b are not particularly limited in number and position.

(36) The following describes a manufacturing method for the coil component 10 according to the present embodiment.

(37) FIGS. 4A to 17B are views for explaining the manufacturing method for the coil component 10 according to the present embodiment. “A” of each of FIGS. 4 to 13 is a schematic plan view, “B” is a cross-sectional view taken along line X.sub.1-X.sub.1 in “A”, and “C” is a cross-sectional view taken along line X.sub.2-X.sub.2 in “A”. FIG. 14A is a cross-sectional view corresponding to the position of line X.sub.1-X.sub.1 in FIG. 4A, etc., and FIG. 14B is a cross-sectional view corresponding to the position of line X.sub.2-X.sub.2 in FIG. 4A, etc. “A” and “B” of each of FIGS. 15 to 17 are each a cross-sectional view corresponding to line X.sub.1-X.sub.1 in FIG. 4A, etc.

(38) In manufacturing the coil component 10, first the insulating gap layer 30 (insulating resin layer) is formed on the upper surface of a carrier substrate 60 having a predetermined strength, as illustrated in FIGS. 4A to 4C. While a transparent glass substrate is preferably used as the material of the carrier substrate 60 in terms of easiness of peeling of an intermediate from the carrier substrate 60, a ferrite substrate, a silicon substrate, or the like may be used. Further, a formation method for the insulating gap layer 30 is also not particularly limited. Specifically, the insulating gap layer 30 may be formed by applying a resin material onto the surface of the carrier substrate 60 according to a spin coat method or a printing method or by attaching the insulating gap layer 30 previously molded into a film-like shape to the carrier substrate 60. While the following describes an example in which a single coil component is formed on the carrier substrate 60 for descriptive convenience, a mass production process in which many coil components are formed on one carrier substrate 60 is actually adopted.

(39) Then, the first conductor layer 40a is formed on a first surface 30a (first main surface) of the insulating gap layer 30. To this end, a thin-film formation process such as sputtering or a thin copper foil is used to form a seed layer SL (seed pattern). As illustrated in FIGS. 4A to 4C, the seed layer SL includes the spiral pattern C1 having about three turns, the inner auxiliary pattern 42a and an inner dummy pattern 43a which are formed in the inner diameter area of the spiral pattern C1, and an outer dummy pattern 43b formed in the outer peripheral area of the spiral pattern C1. The spiral pattern C1 is wound clockwise from an outer peripheral end 41b toward an inner peripheral end 41a. The thickness of the seed layer SL is preferably 1 μm to 10 μm. When the thickness of the seed layer SL exceeds 10 μm, the top shape of the spiral pattern in cross section formed in the electrolytic plating process to be described later may be rounded, which may result in increase in the resistance value of the inductor.

(40) The inner auxiliary pattern 42a is connected to a part of the innermost turn of the spiral pattern C1 to short-circuit the spiral pattern C1 and inner dummy pattern 43a. This allows a negative potential to be applied to the outer peripheral end and innermost turn of the spiral pattern C1 in the electrolytic plating process to be described later, whereby an electrolytic plating layer can be made uniform from the inner peripheral end to outer peripheral end of the spiral pattern C1. The outer dummy pattern 43b is insulated from the spiral pattern C1.

(41) Then, as illustrated in FIGS. 5A to 5C, a photosensitive permanent resist pattern 51a (resist post) formed of a negative pattern of the spiral pattern C1 is formed. The inner auxiliary pattern 42a connected to the innermost turn of the spiral pattern C1 is covered with the resist pattern 51a.

(42) Then, as illustrated in FIGS. 6A to 6C, the seed layer SL is grown by plating to a desired film thickness by the electrolytic plating. At this time, the upper surface of the inner auxiliary pattern 42a is covered with the resist pattern 51a, so that the inner auxiliary pattern 42a is not grown by plating, and the thickness thereof is still equal to the thickness of the seed layer SL.

(43) When the inner auxiliary pattern 42a is not formed, the inner dummy pattern 43a is a floating pattern insulated from the spiral pattern C1, so that the inner dummy pattern 43a cannot be grown by plating only by applying the negative potential to the outer peripheral end 41b of the spiral pattern C1 and the outer dummy pattern 43b in the electrolytic plating process. However, in the present embodiment, the inner auxiliary pattern 42a is formed in the inner diameter area of the spiral pattern C1 to short-circuit the inner dummy pattern 43a and the innermost turn of the spiral pattern C1, thereby allowing the inner dummy pattern 43a to be grown by plating, which in turn can uniformly form an electrolytic plating layer PL having a sufficient thickness on the entire plated surface.

(44) Then, the upper end portion of the resist pattern 51a is removed by way of, e.g., asking, to expose the head of the spiral pattern C1 and, thereafter, as illustrated in FIGS. 7A to 7C, a resist pattern 51b that covers the upper surface of the spiral pattern C1 is formed. In this way, the interlayer insulating layer 50a composed of the resist patterns 51a and 51b and surrounding the spiral pattern C1 is formed.

(45) Thereafter, the processes from FIGS. 4A to 7C are repeated to alternately form the second to fourth conductor layers 40b to 40d and second to fourth interlayer insulating layers 50b to 50d.

(46) In forming the second conductor layer 40b, the thin-film formation process or a thin copper foil is used to form the seed layer SL (seed pattern), as illustrated in FIGS. 8A to 8C. The seed layer SL includes the spiral pattern C2 having three turns, the inner auxiliary pattern 42a and inner dummy pattern 43a which are formed in the inner diameter area of the spiral pattern C2, and the outer auxiliary pattern 42b and outer dummy pattern 43b which are formed in the outer peripheral area of the spiral pattern C2. The spiral pattern C2 is wound clockwise from the inner peripheral end toward the outer peripheral end. The inner auxiliary pattern 42a is connected to the innermost turn of the spiral pattern C2, and the outer auxiliary pattern 42b is connected to the outermost turn of the spiral pattern C2.

(47) Thereafter, as illustrated in FIGS. 9A to 9C, the photosensitive permanent resist pattern 51a (resist post), electrolytic plating layer PL, and resist pattern 51b are sequentially formed in this order. The upper surfaces of the respective inner auxiliary pattern 42a and outer auxiliary pattern 42b are covered with the resist pattern 51a, so that the inner auxiliary pattern 42a and outer auxiliary pattern 42b are not grown by plating at the formation of the electrolytic plating layer PL.

(48) When the inner auxiliary pattern 42a and outer auxiliary pattern 42b are not formed, the inner dummy pattern 43a and spiral pattern C2 are floating patterns insulated from the outer dummy pattern 43b, so that the inner dummy pattern 43a and spiral pattern C2 cannot be grown by plating only by applying the negative potential to the outer dummy pattern 43b in the electrolytic plating process. However, in the present embodiment, the inner auxiliary pattern 42a and outer auxiliary pattern 42b are formed in the inner diameter area and outer peripheral area of the spiral pattern C2, respectively, to short-circuit the inner dummy pattern 43a and the innermost turn of the spiral pattern C2 and short-circuit the outer dummy pattern 43b and the outermost turn of the spiral pattern C2, thereby allowing the spiral pattern C2 and inner dummy pattern 43a to be grown by plating, which in turn can uniformly form the electrolytic plating layer PL having a sufficient thickness on the entire plated surface. Thus, the spiral pattern C2 having a uniform thickness over the entire length thereof can be formed.

(49) In forming the third conductor layer 40c, the thin-film formation process or a thin copper foil is used to form the seed layer SL (seed pattern), as illustrated in FIGS. 10A to 10C. The seed layer SL includes the spiral pattern C3 having three turns, the inner auxiliary pattern 42a and inner dummy pattern 43a which are formed in the inner diameter area of the spiral pattern C3, and the outer auxiliary pattern 42b and outer dummy pattern 43b which are formed in the outer peripheral area of the spiral pattern C3. The spiral pattern C3 is wound clockwise from the outer peripheral end 41b toward the inner peripheral end 41a. The inner auxiliary pattern 42a is connected to the innermost turn of the spiral pattern C3, and the outer auxiliary pattern 42b is connected to the outermost turn of the spiral pattern C3.

(50) Thereafter, as illustrated in FIGS. 11A to 11C, the photosensitive permanent resist pattern 51a (resist post), electrolytic plating layer PL, and resist pattern 51b are sequentially formed in this order. The upper surfaces of the respective inner auxiliary pattern 42a and outer auxiliary pattern 42b are covered with the resist pattern 51a, so that the inner auxiliary pattern 42a and outer auxiliary pattern 42b are not grown by plating at the formation of the electrolytic plating layer PL.

(51) When the inner auxiliary pattern 42a and outer auxiliary pattern 42b are not formed, the inner dummy pattern 43a and spiral pattern C3 are floating patterns insulated from the outer dummy pattern 43b, so that the inner dummy pattern 43a and spiral pattern C3 cannot be grown by plating only by applying the negative potential to the outer dummy pattern 43b in the electrolytic plating process. However, in the present embodiment, the inner auxiliary pattern 42a and outer auxiliary pattern 42b are formed in the inner diameter area and outer peripheral area of the spiral pattern C3, respectively, to short-circuit the inner dummy pattern 43a and the innermost turn of the spiral pattern C3 and short-circuit the outer dummy pattern 43b and the outermost turn of the spiral pattern C3, thereby allowing the spiral pattern C3 and inner dummy pattern 43a to be grown by plating, which in turn can uniformly form the electrolytic plating layer PL having a sufficient thickness on the entire plated surface. Thus, the spiral pattern C3 having a uniform thickness over the entire length thereof can be formed.

(52) In forming the fourth conductor layer 40d, the thin-film formation process or a thin copper foil is used to form the seed layer SL (seed pattern), as illustrated in FIGS. 12A to 12C. The seed layer SL includes the spiral pattern C4 having three turns, the inner auxiliary pattern 42a and inner dummy pattern 43a which are formed in the inner diameter area of the spiral pattern C4, and the outer dummy pattern 43b formed in the outer peripheral area of the spiral pattern C4. The spiral pattern C4 is wound clockwise from the inner peripheral end 41a toward the outer peripheral end 41b. The inner auxiliary pattern 42a is connected to the innermost turn of the spiral pattern C4.

(53) Thereafter, as illustrated in FIGS. 13A to 13C, the photosensitive permanent resist pattern 51a (resist post), electrolytic plating layer PL, and resist pattern 51b are sequentially formed in this order. The upper surface of the drawn part of the inner auxiliary pattern 42a and the upper surface of the outer auxiliary pattern 42b are covered with the resist pattern 51a, so that the drawn parts of the respective inner auxiliary pattern 42a and outer auxiliary pattern 42b are not grown by plating at the formation of the electrolytic plating layer PL.

(54) When the inner auxiliary pattern 42a is not formed, the inner dummy pattern 43a is a floating pattern insulated from the spiral pattern C4, so that the inner dummy pattern 43a cannot be grown by plating only by applying the negative potential to the outer peripheral end 41b of the spiral pattern C4 and to the outer dummy pattern 43b in the electrolytic plating process. However, in the present embodiment, the inner auxiliary pattern 42a is formed in the inner diameter area of the spiral pattern C4 to short-circuit the inner dummy pattern 43a and the innermost turn of the spiral pattern C4, thereby allowing the inner dummy pattern 43a to be grown by plating, which in turn can uniformly form the electrolytic plating layer PL having a sufficient thickness on the entire plated surface. Thus, the spiral pattern C4 having a uniform thickness over the entire length thereof can be formed.

(55) Then, as illustrated in FIGS. 14A and 14B, wet etching is performed to selectively remove the conductor layers 40a to 40d while leaving the spiral patterns C1 to C4. That is, the conductor layers 40a to 40d existing in the inner diameter area 22 and outer peripheral area 23 of the spiral patterns C1 to C4 are removed. While the spiral patterns C1 to C4 are not removed by the etching since they are covered with the interlayer insulating layers 50a to 50d, respectively, the other conductor patterns are removed by the etching. As a result, a space is formed in the inner diameter area 22 surrounded by the spiral patterns C1 to C4 and the outer peripheral area 23 positioned outside the spiral patterns C1 to C4.

(56) In the process of selectively removing the conductor layers 40a to 40d, a part of the inner auxiliary pattern 42a and a part of the outer auxiliary pattern 42b are removed by over-etching, with the result that the recessed part 50x is formed in the side wall surface of the interlayer insulating layer. In the depth of the recessed part 50x, the exposed surface of the inner auxiliary pattern 42a or outer auxiliary pattern 42b exists.

(57) Then, as illustrated in FIG. 15A, the first magnetic resin layer 11 in a semi-cured state retained on a film 11a made of PET resin is prepared and is laminated on the carrier substrate 60 with the first magnetic resin layer 11 facing the coil part 20. As a result, the first magnetic resin layer 11 is formed in the inner diameter area 22, the outer peripheral area 23, and the upper area 24 of the coil part 20. Alternatively, a composite member in a semi-cured state made of resin containing metal magnetic particles may be embedded in the space formed by the removal of the unnecessary part of the conductor layers 40a to 40d by a printing method.

(58) Then, as illustrated in FIG. 15B, the first magnetic resin layer 11 is pressed to completely embed a gap existing in the inner diameter area 22 and outer peripheral area 23 of the coil part 20 with the first magnetic resin layer 11. In pressing the first magnetic resin layer 11, a part of the first magnetic resin layer 11 enters the recessed part 50x formed in the side wall surface of each of the interlayer insulating layers 50a to 50d, so that even when the thermal expansion coefficient differs between the first magnetic resin layer 11 and the interlayer insulating layers 50a to 50d, adhesion between the first magnetic resin layer 11 and the coil part 20 can be improved by the anchor effect. Further, since the recessed part 50x is formed by removing the seed layer SL having a thickness as small as about 1 μm to 10 μm, the metal magnetic particles contained in the first magnetic resin layer 11 cannot enter the recessed part 50x, and only the resin binder can enter the recessed part 50x. This prevents the metal magnetic particles from contacting the auxiliary patterns 42a and 42b, allowing the insulation performance of the coil pattern to be secured.

(59) Then, as illustrated in FIG. 16A, the film 11a is peeled, and a support plate 61 is bonded to the first magnetic resin layer 11 by an adhesive 62. After that, as illustrated in FIG. 16B, the carrier substrate 60 is peeled. As a result, the back surface 30b (second main surface) of the insulating gap layer 30 is exposed. The support plate 61 is a support member provided for the peeling process of the carrier substrate 60. When it is not necessary to support the whole structure in the peeling process of the carrier substrate 60, the support plate 61 need not be bonded.

(60) While thermal peeling by laser irradiation is preferable as a method of peeling the carrier substrate 60, the peeling may be performed mechanically. When the carrier substrate 60 is thermally peeled, a glass substrate is preferably used as the carrier substrate 60, and laser is irradiated to the insulating gap layer 30 from the back side of the carrier substrate 60. The laser light reaches the insulating gap layer 30 passing through the glass substrate to rapidly heat the insulating gap layer 30, with the result that the adhesion of the insulating gap layer 30 is lowered at the boundary with the carrier substrate 60, thus making it possible to easily peel the carrier substrate 60 from the insulating gap layer 30.

(61) Then, as illustrated in FIG. 17A, the support plate 61 is peeled, and the intermediate is reversed up and down, followed by lamination of the second magnetic resin layer 12 in a semi-cured state retained on a film 12a made of PET resin on the intermediate with the second magnetic resin layer 12 facing the insulating gap layer 30. As a result, the second magnetic resin layer 12 is formed on the back surface 30b of the insulating gap layer 30.

(62) Then, as illustrated in FIG. 17B, the first and second magnetic resin layers 11 and 12 are pressed and, thereafter, the first and second magnetic resin layers 11 and 12 in a semi-cured state are applied with heat or irradiated with ultraviolet ray to completely cure the first and second magnetic resin layers 11 and 12. Thereafter, the film 12a is peeled. Further, dicing is performed for individualization in a mass production process, followed by formation of the external terminals E1 and E2 illustrated in FIG. 1, whereby the coil component 10 according to the present embodiment is completed.

(63) FIG. 18 is a plan view illustrating a modification of the planar shape of the auxiliary pattern.

(64) As illustrated in FIG. 18, in a plan view, the inner auxiliary pattern 42a and the outer auxiliary pattern 42b are each not a straight pattern extending straight from the spiral pattern C1 toward the inner dummy pattern 43a or outer dummy pattern 43b but are each a crank pattern having a bend. The number of bends is not limited, but may be any number. Thus, the auxiliary pattern 42 may be, for example, a meander pattern. Using the auxiliary pattern 42 having such a bend can increase the distance from the leading end of the auxiliary pattern 42 to the spiral pattern, thereby making it possible to avoid a situation where not only the auxiliary pattern 42 but also a part of the spiral pattern C1 is removed by over-etching.

(65) As described above, the coil component 10 according to the present embodiment has the coil part 20 in which the first to fourth conductor layers 40a to 40d and first to fourth interlayer insulating layers 50a to 50d are alternately laminated and magnetic resin layers 11 and 12 covering the coil part 20. The first to fourth conductor layers 40a to 40d have the spiral patterns C1 to C4, respectively, and the auxiliary pattern 42 connected to the innermost turn and/or the outermost turn of each of the spiral patterns C1 to C4. The interlayer insulating layers 50a to 50d cover the upper surfaces and side surface of the respective spiral patterns C1 to C4 and also cover the upper surface of each auxiliary pattern 42. The recessed part 50x for exposing the side surface of the auxiliary pattern 42 is formed in the side wall surface 50y of each of the interlayer insulating layers 50a to 50d, and the resin binder constituting the first magnetic resin layer 11 is embedded in the recessed part 50x, so that it is possible to improve the adhesion between the interlayer insulating layers 50a to 50d and the magnetic resin layer by the anchor effect while securing insulation reliability of the spiral patterns C1 to C4.

(66) Further, the manufacturing method for the coil component 10 according to the present embodiment includes: a process of forming the coil part 20 by alternately repeating a process of forming the conductor layers 40a to 40d including the spiral patterns C1 to C4, respectively, and a process of forming the interlayer insulating layers 50a to 50d covering the upper surfaces and side surfaces of the respective spiral patterns C1 to C4; and a process of forming the magnetic resin layer 11 covering the coil part 20. The process of forming the coil part 20 includes a process of forming the recessed part 50x in the side wall surface 50y of each of the interlayer insulating layers 50a to 50d. The process of forming the magnetic resin layer 11 includes a process of embedding a part of the magnetic resin layer 11 in the recessed part 50x. The process of forming the conductor layers 40a to 40d includes a process of forming the seed layers SL each including the spiral pattern and auxiliary pattern, a process of forming the resist pattern 51a selectively covering each seed layer SL, a process of applying electrolytic plating to each seed layer SL, and a process of selectively removing an unnecessary part of the conductor pattern by etching while leaving the spiral pattern. The process of removing an unnecessary conductor pattern includes a process of removing at least a part of the auxiliary pattern and simultaneously serves as a process of forming the recessed part 50x, so that it is possible to form the recessed part only by removing the unnecessary conductor pattern without conducting a special process.

(67) The present invention has thus been shown and described with reference to specific embodiments. However, it should be noted that the present invention is not limited to the details of the described arrangements but changes and modifications may be made without departing from the scope of the appended claims.

(68) For example, in the above embodiment, the outer auxiliary pattern 42b is formed only in the second and third conductor layers 40b and 40c (intermediate layers) and omitted in the first and fourth conductor layers 40a and 40d; however, the outer auxiliary pattern 42b may be formed in the first and fourth conductor layers 40a and 40d. That is, both the inner auxiliary pattern 42a and outer auxiliary pattern 42b may be connected to all the first to fourth spiral patterns C1 to C4. Further, although two inner auxiliary patterns 42a or two outer auxiliary patterns 42b are formed in one spiral pattern in the above embodiment, the number of the auxiliary patterns to be formed in one spiral pattern is not particularly limited and may be three or more, or one.

(69) Further, although the coil part 20 has the four conductor layers 40a to 40d in the above embodiment, the number of the conductor layers is not particularly limited, but may be any number. Further, the number of turns of the coil pattern is also not particularly limited as long as the present invention remains effective.

(70) Further, although the magnetic resin is used as a sealing member covering the coil part 20 in the above embodiment, non-magnetic resin not containing metal magnetic particles may be used to cover the coil part 20. Also in this case, adhesion between the sealing resin layer and the coil part 20 can be improved by the anchor effect.

(71) Further, although the auxiliary pattern 42 is not completely removed but remains to some extent in the coil component 10 according to the present embodiment, it may be completely removed as long as coil characteristics are not affected.