JP5113025B2 - Coil structure and manufacturing method thereof - Google Patents

Description

  The present invention relates to a coil structure and a manufacturing method thereof, and more particularly to a coil structure having a coil formed of a wiring layer of an electronic circuit board and a manufacturing method thereof.

  In recent years, with the downsizing and higher functionality of electronic equipment, the number of external electronic components mounted on electronic circuit boards (including multilayer wiring boards in which a plurality of wiring layers and insulating layers are alternately stacked) Reduction is required. For this reason, development of a technique for incorporating electronic components such as an inductance element and a capacitance element in an electronic circuit board is underway.

  The following are known as inductance elements (coil structures) built in the electronic circuit board.

  One of them is a coil element that is formed only by a spiral wiring pattern without forming a magnetic core.

  There is also a coil-embedded multilayer board in which a plurality of wiring layers of an electronic circuit board (multilayer wiring board) are patterned into a predetermined shape and connected by vias (vertical wiring) to form a spiral coil. In the center of the coil, a core of magnetic material (magnetic core) is arranged (Patent Document 1).

Furthermore, there is an inductor structure having a structure in which a magnetic core is fitted in the center of a spiral conductor formed along the inner wall of a through hole that penetrates an electronic circuit board (Patent Document 2).
JP-A-2005-347286 JP 2006-13117 A

  In recent years, due to the increase in the number of terminals of semiconductor devices mounted on an electronic circuit board and the miniaturization of the electronic circuit board, the density of wiring routed inside the electronic circuit board has increased, and the wiring has been built into the electronic circuit board. There is also a demand for further downsizing of the coil structure.

  However, it is difficult to obtain a large inductance in a coil element formed only by spiral wiring without forming a magnetic core, and it is necessary to increase the number of conductor turns to obtain a certain inductance. For this reason, the area (volume) which a coil element occupies will become large.

  On the other hand, an inductor having a magnetic core disposed at the center of a coil can obtain a large inductance with a small number of conductor turns, but has a problem that eddy current loss due to the magnetic core increases when an alternating current is applied.

  The present invention was created in view of the above-described problems, and provides a coil structure built in an electronic circuit board, which can be reduced in size with low loss, and a method for manufacturing the same. And

According to one aspect of the present invention, there is provided a coil structure formed on an electronic circuit board in which a plurality of wiring layers and insulating layers are alternately laminated on a base material, wherein the insulating layer covers the wiring layer. The wiring layer includes a coil made of a wiring pattern, and a magnetic core disposed at the center of the coil and divided by a plurality of columnar portions extending in a direction perpendicular to the wiring layer. The magnetic core and the magnetic core of the other layer are formed at the same position in the in-plane direction of each layer, and an insulating layer is provided between the magnetic core on the lower layer side and the magnetic core on the upper layer side. A coil structure is formed .

According to another aspect, there is provided a manufacturing method of a coil structure formed inside an electronic circuit board in which wiring layers and insulating layers are alternately laminated on a base material, Forming a seed layer on one surface; forming a first plating resist layer having a coil-shaped opening on the seed layer; and depositing a conductive material in the opening of the first plating resist layer A step of forming a coil, and after removing the first plating resist layer, a second plating resist layer that covers the seed layer and the coil and has a plurality of openings on the center side of the coil. A step of forming, a step of depositing a magnetic material in a plurality of openings of the second plating resist layer to form a magnetic core divided by a plurality of columnar portions, and a step of forming the second plating resist layer. Removed And removing the seed layer exposed, said after removing the seed layer, and a step of forming an insulating layer covering the coil and the magnetic core, the magnetic body from the formation of the seed layer By repeating the steps up to the formation of the insulating layer covering the core, there is provided a method of manufacturing a coil structure that forms a magnetic core that is divided into a plurality of pieces in a direction perpendicular to the wiring pattern .

  According to the above aspect, the coil structure includes the magnetic core near the center of the coil. For this reason, a large inductance can be obtained with a smaller number of conductor turns than an air-core coil. For this reason, a coil structure can be reduced in size.

  Furthermore, since the magnetic core is divided by a plurality of columnar portions extending in a direction perpendicular to the wiring layer, the flow path of eddy current generated in the direction parallel to the wiring layer in the magnetic core is finely divided. Thereby, the increase in the eddy current in a magnetic body core can be suppressed, and a coil structure with few losses is obtained.

  Moreover, according to the said viewpoint, since a buildup method is used, a coil structure can be manufactured accurately and efficiently.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a perspective view showing a coil structure 10 according to an embodiment of the present invention, and FIG. 2 shows the coil structure 10 shown in FIG. 1 as a magnetic core 11 and coils 12A and 12B. It is shown in a disassembled form. In the illustrations of FIGS. 1 and 2, only the constituent members related to the present invention are shown.

  The coil structure 10 according to the present embodiment has a structure in which a magnetic core 11 is disposed at the center of a laminated coil 12A and coil 12B as shown in FIG.

  The magnetic core 11 is divided into a plurality of columnar portions 11a made of a magnetic material. Each columnar portion 11a has a hexagonal cross section parallel to the upper surface of the base material (described later), and is formed to extend in a uniform cross section in a direction perpendicular to the upper surface of the base material (a direction penetrating the wiring layer). Yes. The hexagonal columnar portions 11a are arranged in a honeycomb shape with a predetermined interval (for example, about 10 to 500 μm) therebetween. A resin constituting an insulating layer (described later) is filled between the columnar portions 11a. For this reason, each columnar part 11a is electrically insulated. The size of the columnar part 11a (the length of the hexagonal side constituting the cross section) can be set to, for example, about 50 to 100 μm.

  Thus, the columnar portion 11a is formed in a hexagonal cross section and is arranged in a honeycomb shape, so that the volume fraction of the magnetic body in the magnetic core 11 can be increased. Thereby, a high inductance is obtained.

  For example, Ni or an alloy containing Ni can be used as the magnetic body constituting the columnar portion 11a. In addition, a magnetic material containing at least one element of Mn, Fe, Co, and Ni may be used.

  In the coil structure 10, a plurality of coils 12 </ b> A and coils 12 </ b> B are alternately stacked with a predetermined interval in the height direction. As shown in FIG. 2, the coil 12 </ b> A and the coil 12 </ b> B are spiral wiring patterns formed along a plane parallel to the surface of a base material (described later). The coil 12A is formed in a clockwise spiral (a spiral toward the outer periphery by clockwise rotation), and the coil 12B is formed in a counterclockwise spiral (a spiral toward the outer periphery by counterclockwise rotation).

Pads 12a that are formed wider than the other portions are provided at the inner peripheral ends of the coils 12A and 12B. In addition, pads 12b that are formed wider than the other portions are provided at the outer peripheral ends of the coils 12A and 12B. Each pad 12a is formed at the same position in the in-plane direction parallel to the substrate surface. Each pad 12b is also formed at the same position in the in-plane direction parallel to the substrate surface. Vias 13 are formed in the pads 12a and 12b. The coils 12 </ b> A and 12 </ b> B adjacent in the height direction are connected via this via 13.

  The wiring width and thickness of the coils 12A and 12B are appropriately selected according to the design values such as the rated current required for the coil structure 10, but here, as an example, the width is about 20 to 200 μm and the thickness. Can be about 15 μm. In the illustrated example, the number of turns of the coils 12A and 12B is three, but is not particularly limited to this, and is appropriately set according to the required inductance. Further, the inner diameters of the coils 12A and 12B can be about 500 to 5000 μm, for example, and the outer diameter can be about 1000 to 10,000 μm, for example.

  The coils 12A and 12B are connected in series so that the directions of currents flowing through the coils are the same. That is, in the example shown in FIGS. 1 and 2, the pad 12 a of the first layer (coil 12 </ b> A) and the pad 12 a of the second layer (coil 12 </ b> B) are connected via the via 13. Further, the pad 12b of the second layer (coil 12B) and the pad 12b of the third layer (coil 12A) are connected via the via 13. Furthermore, the pad 12a of the third layer (coil 12A) and the pad 12a of the fourth layer (coil 12B) are connected via the via 13. With such a connection, the coils are connected in series. For example, when a current flowing in the direction from the pad 12b of the first layer (coil 12A) to the pad 12b of the fourth layer (coil 12B) is passed, the arrow A1 in FIG. As shown in -A4, the direction of the current flowing through each coil is the same. Thereby, even if there are few turns of each coil 12A, 12B, the coil structure 10 which has a sufficiently high inductance is obtained.

  A wiring 14 is connected to the pad 12b of the first layer coil 12A and the pad 12b of the fourth layer coil 12B. The wiring 14 extends from the wiring formed in the other part of the electronic circuit board. In the example shown in FIG. 2, the first layer pad 12b and the wiring 14 are connected via the via 13, and the fourth layer pad 12b and the wiring 14 are connected directly (integrally). The present embodiment is not limited to this, and other appropriate connection structures can be selected.

  Hereinafter, the manufacturing method of the coil structure 10 according to the present embodiment will be described with reference to FIGS. In the following description, only the configuration of the coil structure 10 and its peripheral portion related to the present invention will be described in the multilayer wiring board.

  Prior to the production of the coil structure 10, as shown in FIG. 3A, the wiring 14 and the resin layer (insulating layer) 15 are formed on the base material 9 which becomes the base of the electronic circuit board (multilayer wiring board). Prepared structure. In this structure, a copper (Cu) layer (wiring layer) is formed on the upper surface of a base material 9 (for example, a glass epoxy resin substrate), and this is patterned to form wirings 14. In addition, for example, it is obtained by forming a resin layer (insulating layer) 15 made of an epoxy resin or the like.

  In the first step (see FIGS. 3A to 3C), the first layer coil 12A is formed.

  First, as shown in FIG. 3B, a hole is formed in the insulating layer 15A at a predetermined position above the wiring 14 to form a via hole 15a. This drilling process can be performed with a laser processing apparatus or the like. Thereafter, a desmear process is performed to remove smears generated during the drilling of the insulating layer 15.

  Next, a thin seed layer (feeding layer) 16 made of copper (Cu) or a metal film containing copper is formed on the upper surface of the insulating layer 15 and the inner wall of the via hole 15a by electroless plating or sputtering (FIG. 3 ( c)). The thickness of the seed layer 16 is, for example, about 0.1 to 5 μm.

  Next, as shown in FIG. 4A, a plating resist layer 17 (first plating resist layer) is formed on the seed layer 16 using a patterning material, and an opening 17a is formed at a required location. To do. The opening 17a of the resist layer 17 is patterned in a clockwise spiral shape according to the shape of the coil 12A to be formed. As the patterning material, a photosensitive dry film or a liquid photoresist (for example, a liquid resist such as an acrylic resin, a novolac resin, and an epoxy resin) can be used.

  Next, a coil 12A is formed on the seed layer 16 exposed from the opening 17a of the resist layer 17 by electrolytic copper (Cu) plating using the seed layer 16 as a power feeding layer (see FIG. 4B). ). At this time, copper (Cu) is filled in the via hole 15a in the pad 12b portion to form the via 13, and the first layer coil 12A and the wiring 14 are connected.

  Thereafter, the resist layer 17 used as the plating resist is removed. The structure having the cross section shown in FIG. 4C is completed through the above steps.

  Here, FIG. 5 shows a planar structure of the coil 12A shown in FIG. In addition, the cross section shown in FIG.4 (c) respond | corresponds to the II line | wire of FIG. As shown in FIG. 5, the first coil 12A is formed in a clockwise spiral shape.

  In the next step (see FIGS. 6A to 6C), a magnetic core is formed at the center of the coil 12A.

  First, as shown in FIG. 6A, a plating resist layer 18 is formed on the coil 12A and the exposed seed layer 16 using a patterning material, and an opening 18a is formed at a required location. The opening 18a of the resist layer 18 is patterned into a shape in which hexagonal openings are arranged in a honeycomb shape according to the shape of the magnetic core 11 to be formed. The patterning material can be the same material as that of the resist layer 17 described above.

  Next, as shown in FIG. 6B, a magnetic material is deposited on the seed layer 16 exposed from the opening 18a of the resist layer 18 by electrolytic plating using the seed layer 16 as a power feeding layer. Thus, the magnetic core 11 divided into a plurality of columnar portions 11a is formed. Thickening the magnetic material to be deposited is preferable because the volume fraction of the magnetic material of the magnetic material core 11 is increased and the inductance can be further increased. Here, as an example, it is assumed that about 40 μm of magnetic material is deposited. It is preferable that the magnetic material to be deposited is Ni or Ni alloy because the adhesion between the seed layer 16 made of copper (Cu) and the magnetic core 11 is good.

  Further, a copper (Cu) layer (adhesion layer) 19 is formed on the columnar portion 11 a exposed from the opening 18 a of the resist layer 18 by electrolytic plating. The copper layer 19 is formed in order to improve adhesion between a resin layer (insulating layer 20) described later and the upper surface of the columnar portion 11a. Here, the copper layer 19 has a thickness of about 3 μm, for example.

  Thereafter, the resist layer 18 used as the plating resist is removed. Then, the exposed seed layer 16 is removed by etching to complete a structure having a cross section shown in FIG.

  FIG. 7 shows a planar structure of the structure shown in FIG. The cross section shown in FIG. 6C corresponds to the line II in FIG. As shown in FIG. 7, the magnetic core 11 in which hexagonal columnar portions 11a are arranged in a honeycomb shape is formed near the center of the spiral coil 12A.

  Next, in order to improve the adhesion between the coil 12A and the copper layer 19 and a resin layer (insulating layer 20) described later, the coil 12A and the copper layer 19 are roughened. Thereafter, an insulating layer 20 that covers the insulating layer 15, the coil 12 </ b> A, and the magnetic core 11 is formed. The insulating layer 20 is formed to a thickness of about 45 μm from the surface of the insulating layer 15. As the insulating layer 20, for example, an epoxy resin can be used.

  Through the above steps, the structure shown in FIG. 8A is formed, and the first structure of the coil structure 10 according to the present embodiment is completed.

  In the subsequent steps, the second layer coil 12B and the magnetic core 11 are sequentially formed.

  The second layer coil 12B is formed by the same process (see FIGS. 3A to 3C) as the formation of the first layer coil 12A. However, when the second layer coil 12B is formed, the via 13 is formed on the pad 12a on the inner peripheral side of the first layer coil 12A.

  On the other hand, the second-layer magnetic core 11 has the same planar structure as that of the first layer in the same process as the formation process of the first-layer magnetic core 11 (see FIGS. 6A to 6C). It is laminated on the first magnetic core 11 as it is. As a result, the magnetic core 11 (columnar portion 11 a) extends in a direction perpendicular to the upper surface of the substrate 9.

  Through the above steps, the second layer coil 12B and the magnetic core 11 (columnar portion 11a) shown in FIG. 8B are completed. Here, FIG. 9 shows a planar structure of the second layer coil 12B and the magnetic core 11 of FIG. 8B.

  As shown in FIG. 9, the second layer coil 12B is formed in a left-handed spiral shape. The pad 12a of the second layer coil 12B is formed at a position immediately above the pad 12a of the first layer coil 12A, and these pads are connected via vias 13 (see FIG. 8B). Is done. On the other hand, the magnetic core 11 (columnar portion 11a) is laminated on the first magnetic core 11 with the same planar structure, and extends in a direction perpendicular to the paper surface of FIG.

  Thereafter, the second layer of the coil structure 10 is formed by forming the insulating layer 21 that covers the second coil 12B and the magnetic core 11 of the coil structure (see FIG. 10).

  Thereafter, the same process is repeated to form the third layer coil 12A and the magnetic core 11, and the insulating layer 22 covering the third layer coil 12A and the magnetic core 11 is formed. The third layer coil 12A is formed in a right-handed spiral shape similar to the first layer coil 12A, and the via 13 is formed on the pad 12b of the second layer coil 12B. Connect to coil 12B. The third-layer magnetic core 11 is laminated on the second-layer magnetic core 11 with the same planar structure as the first and second layers.

Next, the fourth layer coil 12B is formed on the insulating layer 22 in the same process as described in FIGS. The fourth layer coil 12B has a left-handed spiral pattern similar to the second layer coil 12B, and a via 13 is formed on the pad 12a of the third layer coil 12A to form the third layer coil 12A. Connecting. The wiring 14 connected to the fourth layer coil 12B is formed by electrolytic copper (Cu) plating simultaneously with the formation of the coil 12B. After forming the fourth coil 12A, the plating resist layer (not shown) and the exposed seed layer 16 are removed.

  Finally, a protective layer 23 made of a resin material such as an epoxy resin is formed on the fourth layer coil 12B and the insulating layer 22 to complete the coil structure 10 of the present embodiment.

  As described above, the coil structure 10 of the present embodiment includes the magnetic core 11 near the center of the coil. For this reason, a large inductance can be obtained with a smaller number of conductor turns than an air-core coil. Further, since the magnetic core 11 is divided by a plurality of columnar portions 11a extending in the direction penetrating the wiring layer, the flow path of the eddy current generated in the direction parallel to the wiring layer in the magnetic core 11 is fine. Divided. Thereby, increase of the eddy current in the magnetic body core 11 can be suppressed, and the eddy current loss by the magnetic body core can be suppressed.

  Moreover, since the coil structure 10 of this embodiment is formed using a build-up method, it can be manufactured accurately and efficiently.

(Modification 1 of embodiment)
In the manufacturing method described in the above-described embodiment, the magnetic core 11 of the coil structure 10 is formed in a structure divided by the insulating layers 20 and 21 at a certain height (thickness). Of course, the form is not limited. In the embodiment described below, a manufacturing process in which the magnetic core 11 having a structure that is not divided in the height (thickness) direction by the insulating layers 20 and 21 will be described.

  Below, the manufacturing method of the coil structure 24 which concerns on the modification 1 of this embodiment is demonstrated, referring Fig.11 (a)-(c).

  In the first modification, the first coil 12A and the magnetic core 11 are formed by a process similar to the process described with reference to FIGS. 3 to 8A and insulated so as to cover these structures. Layer 20 is formed.

  Next, as shown in FIG. 11A, the insulating layer 20 is polished to expose the upper surface of the columnar portion 11 a constituting the magnetic core 11.

  Thereafter, the second layer coil 12B and the magnetic core 11 are formed. In addition, the formation process of the coil 12B of the 2nd layer and the magnetic body core 11 can be performed by the process similar to having demonstrated referring FIG.8 (b). As a result, the second-layer magnetic core 11 (columnar portion 11a) is laminated on the first-layer magnetic core 11 (columnar portion 11a) via only the thin seed layer 16. That is, the first magnetic core 11 and the second magnetic core 11 are stacked without the insulating layer 20 interposed.

  Next, an insulating layer 21 that covers the second coil 12B and the magnetic core 11 is formed, and the insulating layer 21 is subjected to a polishing process similar to the process described in FIG. The upper surface of the second columnar portion 11a is exposed. Thereafter, the third layer coil 12A, the magnetic core 11 and the insulating layer 22 covering these are formed by the same process as described with reference to FIG.

  Thereafter, the coil layer 12B of the fourth layer is formed by the same process as described with reference to FIG. 10, and the protective layer 23 is finally formed, whereby the coil structure having the cross section shown in FIG. 24 is completed.

  As described above, according to the manufacturing process of the first modification, the upper surfaces of the insulating layers 20 and 21 are polished to expose the upper surfaces of the first and second columnar portions 11a (magnetic cores 11). The magnetic core 11 having a structure in which the portion 11a is laminated through only the thin adhesion layer 16 is obtained. Thereby, the volume fraction of the magnetic body which comprises the magnetic body core 11 can be made high. That is, in the manufacturing method of Modification 1, the number of manufacturing steps increases because a polishing step is required, but the inductance of the manufactured coil structure 24 is further increased.

(Modification 2 of this embodiment)
In the above-described embodiment, the magnetic core 11 is divided by the columnar portion 11a having a hexagonal section, but the present embodiment is not limited to this.

  For example, as shown in FIG. 12A, the magnetic core 11 may have a structure in which a cross section is divided by a columnar part 11b having a quadrangular shape (for example, a square shape). Or as shown in FIG.12 (b), it is good also as a structure where the magnetic body core 11 was divided | segmented by the columnar part 11c whose cross section is a triangle (for example, equilateral triangle). In this case, when the triangular or quadrangular columnar portions 11b and 11c are arranged so as to cover the cross section of the magnetic core 11 with a certain interval as in the illustrated example, the volume of the magnetic body of the magnetic core 11 is set. It is preferable because the fraction is improved.

  The shapes of the coils 12A and 12B are not limited to a substantially circular spiral, and may be a polygonal spiral formed by a straight line and a bent portion. For example, a rectangular spiral such as a pattern indicated by 12C in FIG. 12A or a hexagonal spiral such as a pattern indicated by 12D in FIG. Further, when the number of turns of the coils 12A and 12B is set to 1 or less, a partially cut-out annular pattern may be used.

  Furthermore, the number of layers of the magnetic core 11 and the coils 12A and 12B is not limited to the example shown in FIGS. 1 to 10 and is appropriately selected according to a design value such as inductance necessary for the coil structure. be able to.

  The effect similar to that of the embodiment can be obtained also by the coil structure exemplified in Modification 2 described above.

(Verification of the effect of dividing the magnetic core)
The inventors of the present application performed simulation calculations on eddy currents flowing in the magnetic core when the magnetic core of the coil structure is divided into columns and when the magnetic core is not divided. Here, FIG. 13 and FIG. 14 schematically show the models used in the simulation. FIG. 13 shows a coil structure 30 in which a magnetic core is divided into columns, and FIG. 14 shows a coil structure 40 in which the magnetic core is not divided.

  The magnetic core 31 of the coil structure 30 shown in FIG. 13 has a square cross section, and the length of one side is about 0.1 mm. The magnetic core 31 is divided into 64 (= 8 × 8) pieces by columnar portions 31b having a smaller square cross section. The coil 32 has 10 turns, the length H of the coil 32 in the height direction is about 0.02 mm, and the diameter of the wiring constituting the coil is about 0.015 mm.

  On the other hand, the magnetic core 41 of the coil structure 40 shown in FIG. 14 is integrally formed with the same shape and size as the magnetic core 31 shown in FIG. The coil 32 of the coil structure 40 is the same as the coil 32 of the coil structure 30.

  FIG. 15 and FIG. 16 show the results obtained by calculating the eddy current generated when an alternating current having a frequency of 1 kHz and an average current of 1 mA is applied to the coil 32 in the above model. FIG. 15 shows the distribution of eddy currents generated in the magnetic core divided into columnar shapes, and FIG. 16 shows the distribution of eddy currents generated in the magnetic cores not divided. The numerical values shown in FIGS. 15 and 16 indicate relative values of the magnitude of the eddy current.

  As shown in FIG. 15, in the magnetic core 31 divided into columnar shapes, although eddy current is generated in the columnar portion 31b on the peripheral side of the magnetic core 31, the magnitude of the generated eddy current is relatively small. I understand.

  On the other hand, as shown in FIG. 16, in the magnetic core 41 formed integrally without being divided, an eddy current is generated over the entire magnetic core 41, and the flowing eddy current is larger than that of the magnetic core 31. I understand that.

  From the above, it has been confirmed that by dividing the magnetic core disposed in the center of the coil structure into a plurality of columnar portions, generation of eddy current can be suppressed and a coil structure with less loss can be obtained.

It is a perspective view showing typically the coil structure concerning one embodiment of the present invention. It is a perspective view which decomposes | disassembles into a magnetic body core and a coil typically, and the coil structure of embodiment shown in FIG. It is sectional drawing (the 1) which shows the manufacturing method of the coil structure of embodiment shown in FIG. 1 in order of a process. It is sectional drawing (the 2) which shows the manufacturing method of the coil structure of embodiment shown in FIG. 1 in order of a process. It is a figure which shows the upper surface of the structure corresponding to the cross-sectional structure shown in FIG.4 (c). It is sectional drawing (the 3) which shows the manufacturing method of the coil structure of embodiment shown in FIG. 1 in order of a process. It is a figure which shows the upper surface of the structure corresponding to the cross-sectional structure shown in FIG.6 (c). FIG. 8 is a cross-sectional view (part 4) illustrating the manufacturing method of the coil structure according to the embodiment illustrated in FIG. It is a figure which shows the upper surface of the structure corresponding to the cross section shown in FIG.8 (b). It is sectional drawing which shows the structure of the coil structure of embodiment shown in FIG. It is sectional drawing which shows the modification (modification 1) of the manufacturing process of the coil structure of embodiment shown in FIG. 1 in order of a process. It is a top view which shows the modification (modification 2) of the structure of the coil structure of embodiment shown in FIG. It is a perspective view which shows the simulation model of the coil structure provided with the magnetic body core divided | segmented into columnar shape. It is a perspective view which shows the simulation model of the coil structure provided with the magnetic body core formed integrally. It is a figure which shows the calculation result of the eddy current density in the magnetic body core divided | segmented into columnar shape. It is a figure which shows the calculation result of the eddy current density in the magnetic body core formed integrally.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Coil structure, 11 ... Magnetic body core, 11a, 11b, 11c ... Columnar part, 12A, 12B, 12C, 12D ... Coil, 12a ... Pad (inner peripheral side), 12b ... Pad (outer peripheral side), 13 ... Vias, 14 ... wiring, 15, 20, 21, 22 ... insulating layer (resin layer), 16 ... seed layer, 17, 18 ... resist layer, 19 ... copper (Cu) layer, 23 ... protective layer.

Claims (7)

A coil structure formed on an electronic circuit board in which a plurality of wiring layers and insulating layers are alternately laminated on a base material,
The insulating layer covers the wiring layer;
The wiring layer is
A coil comprising a wiring pattern;
A magnetic core disposed at the center of the coil and divided by a plurality of columnar portions extending in a direction perpendicular to the wiring layer;
Including
The magnetic core and the magnetic core of the other layer are formed at the same position in the in-plane direction of each layer ,
A coil structure , wherein an insulating layer is formed between the magnetic core on the lower layer side and the magnetic core on the upper layer side . The coil according to claim 1, wherein an adhesion layer made of a material that improves adhesion between the magnetic core and the insulating layer is formed between the magnetic core and the insulating layer. Structure.   The coil structure according to claim 1 or 2, wherein a cross section of the columnar portion parallel to the wiring layer is a polygonal shape.   The coil structure according to claim 1 or 2, wherein the magnetic core is made of Ni or an alloy containing Ni.   3. The coil structure according to claim 2, wherein the stacked coils are connected in series and the directions of currents flowing through the coils are the same. A method of manufacturing a coil structure formed inside an electronic circuit board in which wiring layers and insulating layers are alternately laminated on a substrate,
Forming a seed layer on one surface above the substrate;
Forming a first plating resist layer having a coil-shaped opening on the seed layer;
Depositing a conductive material in the opening of the first plating resist layer to form a coil;
After removing the first plating resist layer, covering the seed layer and the coil, and forming a second plating resist layer having a plurality of openings on the center side of the coil;
Depositing a magnetic material in a plurality of openings of the second plating resist layer to form a magnetic core divided by a plurality of columnar parts;
Removing the exposed seed layer after removing the second plating resist layer;
Forming an insulating layer that covers the coil and the magnetic core after removing the seed layer , and
By repeating the steps from the formation of the seed layer to the formation of the insulating layer covering the magnetic core, the magnetic core divided into a plurality of parts in the direction perpendicular to the wiring pattern is formed. A manufacturing method of a coil structure. The method for manufacturing a coil structure according to claim 6, further comprising: forming an adhesion layer made of a material that improves adhesion between the magnetic core and the insulating layer on the magnetic core .

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