# Patent

## Title
Method of manufacturing coil substrate and inductor

## Abstract

A method of manufacturing a coil substrate, includes forming a plurality of structures, each of the structures including a first insulating layer and a metal layer formed on the first insulating layer; forming a stacked structure by stacking the structures while connecting the metal layers of the adjacent structures in series; and shaping the stacked structure such that the metal layers of the structures are shaped at the same time to be in shapes of wirings, each becomes a part of a spiral-shaped coil, to form the spiral-shaped coil in which the wirings of the adjacent structures are connected in series.

## Background
CROSS-REFERENCE TO RELATED APPLICATION
The present application is based on and claims the benefit of priority of Japanese Priority Application No. 2013-214129 filed on Oct. 11, 2013, the entire contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a coil substrate, a method of manufacturing a coil substrate and an inductor including a coil substrate.
2. Description of the Related Art
Recently, the size of an electronic device such as a game device, a smartphone or the like has been becoming smaller and smaller. In accordance with this, it is required for various elements such as an inductor or the like that is mounted on the electronic device to be smaller. As such an inductor that is mounted on the electronic device, one that uses a wire winding coil is known, for example. An inductor using a wire winding coil is used as a power supply circuit or the like of an electronic device, for example (see Patent Document 1, for example).
However, as there is a limitation in reducing the width of the wire winding, the ratio of the area occupied by the wire winding with respect to the entire area of the inductor becomes large if the size of the inductor is to be made smaller. In such a case, it is difficult to form a closed magnetic circuit. Therefore, there is a limitation in downsizing the size of the inductor using the wire winding coil while maintaining sufficient inductance and it is considered that the size of the plan shape of such an inductor is about 1.6 mm×1.6 mm at minimum.
PATENT DOCUMENT


    [Patent Document 1] Japanese Laid-open Patent Publication No. 2003-168610


SUMMARY OF THE INVENTION
The present invention is made in light of the above problems, and provides a smaller coil substrate or the like.
According to an embodiment, there is provided a coil substrate including a stacked structure in which a plurality of structures are stacked, each of the structures including a first insulating layer and a wiring formed on the first insulating layer, which becomes a part of a spiral-shaped coil; and an insulating film that covers a surface of the stacked structure, the spiral-shaped coil being formed by connecting the wirings of the adjacent structures in series.
Note that also arbitrary combinations of the above-described elements, and any changes of expressions in the present invention, made among methods, devices, systems and so forth, are valid as embodiments of the present invention.



BRIEF DESCRIPTION OF THE DRAWINGS
Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.
FIG. 1A to FIG. 10 are views illustrating an example of a coil substrate of an embodiment;
FIG. 2 is a perspective view schematically illustrating a shape of a wiring of each structure constituting the coil substrate of the embodiment;
FIG. 3 is a cross-sectional view illustrating an example of an inductor of the embodiment;
FIG. 4A and FIG. 4B are views illustrating an example of a manufacturing method of the coil substrate of the embodiment;
FIG. 5A and FIG. 5B are views illustrating an example of the manufacturing method of the coil substrate of the embodiment;
FIG. 6A and FIG. 6B are views illustrating an example of the manufacturing method of the coil substrate of the embodiment;
FIG. 7A to FIG. 7C are views illustrating an example of the manufacturing method of the coil substrate of the embodiment;
FIG. 8A to FIG. 8C are views illustrating an example of the manufacturing method of the coil substrate of the embodiment;
FIG. 9A to FIG. 9C are views illustrating an example of the manufacturing method of the coil substrate of the embodiment;
FIG. 10A and FIG. 10B are views illustrating an example of the manufacturing method of the coil substrate of the embodiment;
FIG. 11A to FIG. 11C are views illustrating an example of the manufacturing method of the coil substrate of the embodiment;
FIG. 12A to FIG. 12C are views illustrating an example of the manufacturing method of the coil substrate of the embodiment;
FIG. 13A to FIG. 13C are views illustrating an example of the manufacturing method of the coil substrate of the embodiment;
FIG. 14A to FIG. 14C are views illustrating an example of the manufacturing method of the coil substrate of the embodiment;
FIG. 15A and FIG. 15B are views illustrating an example of the manufacturing method of the coil substrate of the embodiment;
FIG. 16A to FIG. 16C are views illustrating an example of the manufacturing method of the coil substrate of the embodiment;
FIG. 17A and FIG. 17B are views illustrating an example of the manufacturing method of the coil substrate of the embodiment;
FIG. 18 is a view illustrating an example of the manufacturing method of the coil substrate of the embodiment;
FIG. 19 is a view illustrating an example of the manufacturing method of the coil substrate of the embodiment;
FIG. 20 is a view illustrating an example of the manufacturing method of the coil substrate of the embodiment;
FIG. 21A to FIG. 21C are views illustrating an example of the manufacturing method of the coil substrate of the embodiment; and
FIG. 22A to FIG. 22C are view illustrating an example of a manufacturing method of an inductor of the embodiment.



DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention will be described herein with reference to illustrative embodiments. Those skilled in the art will recognize that many alternative embodiments can be accomplished using the teachings of the present invention and that the invention is not limited to the embodiments illustrated for explanatory purposes. It is to be noted that, in the explanation of the drawings, the same components are given the same reference numerals, and explanations are not repeated.
(Structure of Coil Substrate)
The structure of a coil substrate of the embodiment is explained. FIG. 1A to FIG. 1C are views illustrating an example of a coil substrate 1 of the embodiment. FIG. 1C is a plan view, FIG. 1A is a cross-sectional view of FIG. 1C taken along an A-A line, and FIG. 1B is a cross-sectional view of FIG. 1C taken along a B-B line. FIG. 2 is a perspective view schematically illustrating a shape of a wiring of each structure constituting the coil substrate 1 of the embodiment.
With reference to FIG. 1A to FIG. 2, the coil substrate 1 mainly includes a first structure 1A, a second structure 1B, a third structure 1C, a fourth structure 1D, a fifth structure 1E, a sixth structure 1F, a seventh structure 1G, adhesion layers 501 to 507 and an insulating film 70. In FIG. 1C, the insulating layer 207, the adhesion layer 507 and the insulating film 70 formed on the adhesion layer 507 are not illustrated. In FIG. 1C, a portion is illustrated in a dot pattern for explanation purposes.
Further, in the following explanation, the drawings illustrating a method of manufacturing the coil substrate 1 are appropriately referred to. Further, in FIG. 1A to FIG. 10, numerals of open portions are not illustrated, and numerals that are illustrated in the drawings illustrating the method of manufacturing the coil substrate 1 are referred to.
In this embodiment, an adhesion layer 507 side is referred to as an upper side or one side, and an insulating layer 201 side is referred to as a lower side or the other side. Further, a surface of each component at the adhesion layer 507 side is referred to as an upper surface or one surface, and a surface at the insulating layer 201 side is referred to as a lower surface or the other surface. However, the coil substrate 1 may be used in an opposite direction or may be used at an arbitrary angle. Further, in this embodiment, “in a plan view” means that an object is seen in a direction that is normal to one surface of the insulating layer 201, and a “plan shape” means a shape of an object seen in the direction that is normal to the one surface of the insulating layer 201.
As will be explained below, the coil substrate 1 is formed into an inductor 100 (see FIG. 3). Thus, the plan shape of the coil substrate 1 may have about a size such that the plan shape of the inductor 100 has substantially a rectangular shape of about 1.6 mm×0.8 mm, for example, when manufacturing the inductor 100 using the coil substrate 1. The thickness of the coil substrate 1 may be about 0.5 mm, for example.
The plan shape (outer edge) of the coil substrate 1 is not a simple rectangular shape but is similar to the plan shape of an outer edge of each wiring (a seventh wiring 307 or the like) that constitute the coil substrate 1. This is in order to form a large amount of sealing resin 110 around the coil substrate 1 when manufacturing the inductor 100 (see FIG. 3) using the coil substrate 1. Further, the coil substrate 1 is provided with a through hole 1x at the substantially center portion of the coil substrate 1. Similarly, this is in order to form a larger amount of the sealing resin 110 around the coil substrate 1 when manufacturing the inductor 100 (see FIG. 3) using the coil substrate 1. By using insulating resin (epoxy based insulating resin or the like, for example) including magnetic filler such as ferrite or the like as sealing resin 110, and sealing the large amount of the part around the coil substrate 1 including the inside of the through hole 1x, for example, the inductance of the inductor 100 can be made larger.
The first structure 1A includes an insulating layer 201, a first wiring 301, a connecting portion 35 and an insulating layer 401. The insulating layer 201 is formed as an outermost layer (undermost layer in FIG. 1A) of the coil substrate 1. For the material of the insulating layer 201, epoxy based insulating resin or the like may be used, for example. The thickness of the insulating layer 201 may be about 8 to 12 μm, for example.
The first wiring 301 and the connecting portion 35 are formed on the insulating layer 201. The material of the first wiring 301 and the connecting portion 35 may be copper (Cu), copper alloy or the like, for example. The thickness of the first wiring 301 and the connecting portion 35 may be about 12 to 50 μm, for example. The width of the first wiring 301 may be about 50 to 130 μm, for example. The first wiring 301 is a first layer wiring that is a part (about a roll) of a coil, and is patterned in substantially an elliptical shape in a direction illustrated in FIG. 2. Here, a direction along the coil (Y direction) is referred to as a longer direction and a width direction that is perpendicular to the longer direction is referred so as a shorter direction (X direction). The cross-sectional shape of the first wiring 301 in the shorter direction is substantially a rectangular shape.
The connecting portion 35 is formed at one end portion of the first wiring 301. A side surface of the connecting portion 35 is exposed from one side surface 1y of the coil substrate 1 and the exposed portion is connected to an electrode of the inductor 100. The connecting portion 35 is integrally formed with the first wiring 301.
The insulating layer 401 is formed on the insulating layer 201 such as to cover the first wiring 301 and the connecting portion 35. In other words, the first structure 1A includes the insulating layer 201, the first wiring 301 and the connecting portion 35 that are formed on the insulating layer 201 and become a part of the coil, and the insulating layer 401 formed on the insulating layer 201 such as to cover the first wiring 301 and the connecting portion 35. Here, one portion of the connecting portion 35 at the side surface is exposed from the insulating layer 401. The insulating layer 401 is provided with an open portion (open portion 4011 in FIG. 5A) that exposes an upper surface of the first wiring 301, and a part of a via wiring 601 is filled in the open portion to be electrically connected with the first wiring 301. For the material of the insulating layer 401, photosensitive epoxy based insulating resin or the like may be used, for example. The thickness of the insulating layer 401 may be about 5 to 30 μm (the thickness from the upper surface of the first wiring 301), for example.
The second structure 1B is stacked on the first structure 1A through the adhesion layer 501. The second structure 1B includes an insulating layer 202, a second wiring 302 and an insulating layer 402. As the adhesion layer 501, a heat resistance adhesive made of insulating resin such as epoxy based adhesive, polyimide based adhesive or the like may be used, for example. The thickness of the adhesion layer 501 may be about 10 to 40 μm, for example.
Here, in the following, the shape, the thickness, the material and the like of an insulating layer 20n, an insulating layer 40n and an adhesion layer 50n (here, “n” is a natural number more than or equal to 2) are the same as those of the insulating layer 201, insulating layer 401 and the adhesion layer 501 unless otherwise explained.
Further, the insulating layer 20n may be referred to as a first insulating layer and the insulating layer 40n may be referred to as a second insulating layer. Although the insulating layer 20n and the insulating layer 40n are added different numerals for explanation purposes, both function as insulating layers that cover the respective wiring. Thus, the insulating layer 20n and the insulating layer 40n in total may referred to as an insulating layer. Here, the coil substrate 1 may not include the insulating layer 40n when the wirings of the structures can be surely insulated from each other by the adhesion layer 50n. 
The insulating layer 402 is stacked on the adhesion layer 501. A bottom surface and a side surface of the second wiring 302 are covered by the insulating layer 402 and an upper surface of the second wiring 302 is exposed from the insulating layer 402. The material, the thickness and the like of the second wiring 302 may be the same as those of the first wiring 301. The second wiring 302 is a second layer wiring that is a part (about 3⁄4 roll) of the coil, and is patterned in substantially a semi-elliptical shape in the direction illustrated in FIG. 2. The cross-sectional shape of the second wiring 302 in the shorter direction is substantially a rectangular shape.
The insulating layer 202 is stacked on the second wiring 302 and the insulating layer 402. In other words, the second structure 1B has a vertically inversed structure of a structure including the insulating layer 202, the second wiring 302 that is formed on the insulating layer 202 and is a part of the coil, and the insulating layer 402 formed on the insulating layer 202 such as to cover the second wiring 302.
The second structure 1B is provided with an open portion that penetrates the insulating layer 202, the second wiring 302 and the insulating layer 402 whose lower side is in communication with an open portion of the adhesion layer 501 and the open portion of the insulating layer 401. A via wiring 601 is filled in these open portions (an open portion 1023 illustrated in FIG. 7A). The second wiring 302 is electrically connected in series with the first wiring 301 through the via wiring 601. Further, the second structure 1B is provided with an open portion (an open portion 1021 illustrated in FIG. 7A) that penetrates the insulating layer 202 and exposes an upper surface of the second wiring 302, and a via wiring 602 is filled in the open portion. The second wiring 302 is electrically connected to the via wiring 602.
The third structure 1C is stacked on the second structure 1B through the adhesion layer 502. The third structure 1C includes an insulating layer 203, a third wiring 303 and an insulating layer 403.
The insulating layer 403 is stacked on the adhesion layer 502. A bottom surface and a side surface of the third wiring 303 are covered by the insulating layer 403 and an upper surface of the third wiring 303 is exposed from the insulating layer 403. The material, the thickness and the like of the third wiring 303 may be the same as those of the first wiring 301. The third wiring 303 is a third layer wiring that is a part (about a roll) of the coil, and is patterned in substantially a semi-elliptical shape in the direction illustrated in FIG. 2. The cross-sectional shape of the third wiring 303 in the shorter direction is substantially a rectangular shape.
The insulating layer 203 is stacked on the third wiring 303 and the insulating layer 403. In other words, the third structure 1C has a vertically inversed structure of a structure including the insulating layer 203, the third wiring 303 that is formed on the insulating layer 203 and is a part of the coil, and the insulating layer 403 formed on the insulating layer 203 such as to cover the third wiring 303.
The third structure 1C is provided with an open portion that penetrates the insulating layer 203, the third wiring 303 and the insulating layer 403 whose lower side is in communication with an open portion of the adhesion layer 502. The via wiring 603 is filled in these open portions (an open portion 1033 in FIG. 9A). The via wiring 603 is electrically connected to a via wiring 602 that is filled in the open portion of the insulating layer 202 of the second structure 1B. The third wiring 303 is electrically connected in series with the second wiring 302 through the via wirings 602 and 603. Further, the third structure 1C is provided with an open portion (an open portion 1031 in FIG. 8B) that penetrates the insulating layer 203 and exposes an upper surface of the third wiring 303. A via wiring 604 is filled in the open portion. The third wiring 303 is electrically connected to the via wiring 604.
The fourth structure 1D is stacked on the third structure 1C through the adhesion layer 503. The fourth structure 1D includes an insulating layer 204, a fourth wiring 304 and an insulating layer 404.
The insulating layer 404 is stacked on the adhesion layer 503. A bottom surface and a side surface of the fourth wiring 304 are covered by the insulating layer 404 and an upper surface is exposed from the insulating layer 404. The material, the thickness and the like of the fourth wiring 304 are the same as those of the first wiring 301. The fourth wiring 304 is a fourth layer wiring that is a part (about 3⁄4 roll) of the coil, and is patterned in substantially a semi-elliptical shape in the direction illustrated in FIG. 2.
The insulating layer 204 is stacked on the fourth wiring 304 and the insulating layer 404. In other words, the fourth structure 1D has a vertically inversed structure of a structure including the insulating layer 204, the fourth wiring 304 that is formed on the insulating layer 204 and is a part of the coil, and the insulating layer 404 formed on the insulating layer 204 such as to cover the fourth wiring 304.
The fourth structure 1D is provided with an open portion that penetrates the insulating layer 204, the fourth wiring 304 and the insulating layer 404 whose lower side is in communication with an open portion of the adhesion layer 503. The via wiring 605 is filled in these open portions. The via wiring 605 is electrically connected to the via wiring 604 formed in the open portion of the insulating layer 203 of the third structure 1C. The fourth wiring 304 is electrically connected in series with the third wiring 303 through the via wirings 604 and 605. Further, the fourth structure 1D is provided with an open portion that penetrates the insulating layer 204 and exposes an upper surface of the fourth wiring 304. A via wiring 606 is filled in the open portion. The fourth wiring 304 is electrically connected to the via wiring 606.
The fourth structure 1D has the same structure as the second structure 1B and corresponds to a structure obtained by rotating the second structure 1B 180° around an axis of normal of an X-Y plane. The open portions 1041 and 1042 respectively correspond to the open portions 1021 and 1022.
The fifth structure 1E is stacked on the fourth structure 1D through the adhesion layer 504. The fifth structure 1E includes an insulating layer 205, a fifth wiring 305 and an insulating layer 405.
The insulating layer 405 is stacked on the adhesion layer 504. A bottom surface and a side surface of the fifth wiring 305 are covered by the insulating layer 405 and an upper surface of the fifth wiring 305 is exposed from the insulating layer 405. The material, the thickness and the like of the fifth wiring 305 may be the same as those of the first wiring 301. The fifth wiring 305 is a fifth layer wiring that is a part (about a roll) of the coil, and is patterned in substantially a semi-elliptical shape in the direction illustrated in FIG. 2. The cross-sectional shape of the fifth wiring 305 in the shorter direction is substantially a rectangular shape.
The insulating layer 205 is stacked on the fifth wiring 305 and the insulating layer 405. In other words, the fifth structure 1E has a vertically inversed structure of a structure including the insulating layer 205, the fifth wiring 305 that is formed on the insulating layer 205 and is a part of the coil, and the insulating layer 405 formed on the insulating layer 205 such as to cover the fifth wiring 305.
The fifth structure 1E is provided with an open portion that penetrates the insulating layer 205, the fifth wiring 305 and the insulating layer 405 whose lower side is in communication with an open portion of the adhesion layer 504. The via wiring 607 is filled in the open portion (an open portion 1053 illustrated in FIG. 13A and FIG. 13B). The via wiring 607 is electrically connected to a via wiring 606 that is filled in the open portion of the insulating layer 204 of the fourth structure 1D. The fifth wiring 305 is electrically connected in series with the fourth wiring 304 through the via wirings 606 and 607. The fifth structure 1E is provided with an open portion (an open portion 1051 illustrated in FIG. 12B) that penetrates the insulating layer 205 and exposes an upper surface of the fifth wiring 305. A via wiring 608 is filled in the open portion. The fifth wiring 305 is electrically connected to the via wiring 608.
The fifth structure 1E has the same structure as the third structure 1C and corresponds to a structure obtained by rotating the third structure 1C 180° around the normal axis of the X-Y plane. The open portions 1051 and 1052 respectively correspond to the open portions 1031 and 1032.
The sixth structure 1F is stacked on the fifth structure 1E through the adhesion layer 505. The sixth structure 1F includes an insulating layer 206, a sixth wiring 306 and an insulating layer 406.
The insulating layer 406 is stacked on the adhesion layer 505. A bottom surface and a side surface of the sixth wiring 306 are covered by the insulating layer 406 and an upper surface of the sixth wiring 306 is exposed from the insulating layer 406. The material, the thickness and the like of the sixth wiring 306 may be the same as those of the first wiring 301. The sixth wiring 306 is a sixth layer wiring that is a part (about 3⁄4 roll) of the coil, and is patterned in substantially a semi-elliptical shape in the direction illustrated in FIG. 2. The cross-sectional shape of the sixth wiring 306 in the shorter direction is substantially a rectangular shape.
The insulating layer 206 is stacked on the sixth wiring 306 and the insulating layer 406. In other words, the sixth structure 1F has a vertically inversed structure of a structure including the insulating layer 206, the sixth wiring 306 that is formed on the insulating layer 206 and is a part of the coil, and the insulating layer 406 formed on the insulating layer 206 such as to cover the sixth wiring 306.
The sixth structure 1F is provided with an open portion that penetrates the insulating layer 206, the sixth wiring 306 and the insulating layer 406 whose lower side is in communication with an open portion of the adhesion layer 505. The via wiring 609 is filled in the open portion (an open portion 1063 illustrated in FIG. 14A and FIG. 14B). The via wiring 609 is electrically connected to a via wiring 608 formed in the open portion of the insulating layer 205 of the fifth structure 1E. The sixth wiring 306 is electrically connected in series with the fifth wiring 305 through the via wirings 608 and 609. The sixth structure 1F is provided with an open portion (open portion 1061 illustrated in FIG. 14A) that penetrates the insulating layer 206 and exposes an upper surface of the sixth wiring 306. A via wiring 6010 is filled in the open portion. The sixth wiring 306 is electrically connected to the via wiring 6010.
Although the reference numerals are different in the sixth structure 1F and the second structure 1B, the sixth structure 1F has the same structure as the second structure 1B and the open portions 1061 and 1062 respectively correspond to the open portions 1021 and 1022.
The seventh structure 1G is stacked on the sixth structure 1F through the adhesion layer 506. The seventh structure 1G includes an insulating layer 207, a seventh wiring 307, a connecting portion 37 and an insulating layer 407.
The insulating layer 407 is stacked on the adhesion layer 506. A bottom surface and a side surface of each of the seventh wiring 307 and the connecting portion 37 are covered by the insulating layer 407 and an upper surface of each of the seventh wiring 307 and the connecting portion 37 is exposed from the insulating layer 407. The material, the thickness and the like of the seventh wiring 307 and the connecting portion 37 are the same as those of the first wiring 301. The seventh wiring 307 is an uppermost wiring layer, and is patterned in substantially a semi-elliptical shape in the direction illustrated in FIG. 2.
The connecting portion 37 is formed at one end portion of the seventh wiring 307. A side surface of the connecting portion 37 is exposed from another side surface 1z of the coil substrate 1 and the exposed portion is connected to an electrode of the inductor 100. The connecting portion 37 is integrally formed with the seventh wiring 307. The insulating layer 207 is stacked on the seventh wiring 307, the connecting portion 37 and the insulating layer 407. In other words, the seventh structure 1G has a vertically inversed structure of a structure including the insulating layer 207, the seventh wiring 307 and the connecting portion 37 formed on the insulating layer 207, and the insulating layer 407 formed on the insulating layer 207 such as to cover the seventh wiring 307 and the connecting portion 37.
The seventh structure 1G is provided with an open portion that penetrates the insulating layer 207, the seventh wiring 307 and the insulating layer 407 whose lower side is in communication with an open portion of the adhesion layer 506. The via wiring 6011 is filled in these open portions (an open portion 1072 illustrated in FIG. 16A). The via wiring 6011 is electrically connected to a via wiring 6010 formed in the open portion of the insulating layer 206 of the sixth structure 1F. The seventh wiring 307 is electrically connected in series with the sixth wiring 306 through the via wirings 6010 and 6011. As such, in the coil substrate 1, the spiral-shaped coil, from the connecting portion 35 to the connecting portion 37, is formed by connecting the wirings of the adjacent structures in series.
The adhesion layer 507 is stacked on the seventh structure 1G. The adhesion layer 507 is not provided with an open portion. This means that an upper side of the stacked structure in which the first structure 1A to the seventh structure 1G are stacked is covered by the adhesion layer 507, which is an insulating layer, and any conductive materials are not exposed.
In the stacked structure in which the first structure 1A to the seventh structure 1G are stacked, surfaces except the bottom surface and the side surfaces 1y and 1z are covered by the insulating film 70. The inner wall surface of the through hole 1x is also covered by the insulating film 70. The insulating film 70 is provided to prevent a short between the end surfaces of the wirings that are exposed from the stacked structure and conductive materials (magnetic filler or the like) that may be included in the sealing resin 110 when manufacturing the inductor 100 (see FIG. 3). For the insulating film 70, epoxy based insulating resin, acrylic based insulating resin or the like may be used, for example. The insulating film 70 may include filler such as silica or the like. The thickness of the insulating film 70 may be about 20 to 50 μm, for example.
FIG. 3 is a cross-sectional view illustrating an example of the inductor 1 of the embodiment. With reference to FIG. 3, the inductor 100 is a chip inductor in which the coil substrate 1 is sealed by the sealing resin 110 and electrodes 120 and 130 are formed. The plan shape of the inductor 100 may be substantially a rectangular shape having a size of about 1.6 mm×0.8 mm. The thickness of the inductor 100 may be about 1.0 mm, for example. The inductor 100 may be used as a voltage conversion circuit or the like of a small-size electronic device, for example.
In the inductor 100, the sealing resin 110 seals the coil substrate 1 except portions at the one side surface 1y and the other side surface 1z. This means that the sealing resin 110 covers the coil substrate 1 except the portions of the side surfaces where the connecting portions 35 and 37 are exposed. The sealing resin 110 is also formed in the through hole 1x. For the sealing resin 110, insulating resin (epoxy based insulating resin or the like, for example) including magnetic filler such as ferrite or the like may be used, for example. The magnetic material has a function to increase the inductance of the inductor 100.
As such, according to the coil substrate 1, as the through hole 1x is provided and the through hole 1x is also filled with the insulating resin such as the epoxy based insulating resin or the like including the magnetic material, the inductance can be improved. Further, a core made of a magnetic material such as ferrite or the like may be provided in the through hole 1x and the core may be also sealed by the sealing resin 110. The shape of the core may be a column shape, a rectangular parallelepiped shape or the like, for example.
The electrode 120 is formed outside the sealing resin 110 and is electrically connected to a part of the connecting portion 35. Specifically, the electrode 120 is continuously formed at the one side surface of the sealing resin 110 and parts of the upper surface and the lower surface of the sealing resin 110. An inner wall surface of the electrode 120 contacts a side surface of the connecting portion 35 that is exposed at the one side surface 1y of the coil substrate 1 and the electrode 120 and the connecting portion 35 are electrically connected with each other.
The electrode 130 is formed outside the sealing resin 110 and is electrically connected to a part of the connecting portion 37. Specifically, the electrode 130 is continuously formed at the side surface of the sealing resin 110 and parts of the upper surface and the lower surface of the sealing resin 110. An inner wall surface of the electrode 130 contacts a side surface of the connecting portion 37 that is exposed at the other side surface 1z of the coil substrate 1 and the electrode 130 and the connecting portion 37 are electrically connected with each other. For the material of the electrodes 120 and 130, copper (Cu), copper alloy or the like may be used, for example. The electrodes 120 and 130 may be formed by coating copper paste, sputtering of copper, electroless plating or the like, for example. The electrodes 120 and 130 may be a stacked structure of a plurality of metal layers.
(Method of Manufacturing Coil Substrate)
Next, a method of manufacturing the coil substrate of the embodiment is explained. FIG. 4A to FIG. 21C are views illustrating an example of the method of manufacturing the coil substrate of the embodiment. First, steps illustrated in FIG. 4A and FIG. 4B are explained. FIG. 4A is a plan view, and FIG. 4B is a cross-sectional view of FIG. 4A taken along a direction parallel to a Y-Z plane in FIG. 4A in the vicinity of one of individual areas C (which will be explained below). In the steps illustrated in FIG. 4A and FIG. 4B, first, a flexible reel (tape) insulating resin film is prepared as the substrate 101 (first substrate).
Then, sprocket holes 10z are continuously formed at both end positions of the substrate 101 in a shorter direction (Y direction in FIG. 4A and FIG. 4B) along a longer direction (X direction in FIG. 4A and FIG. 4B) with substantially a same interval, by press working or the like. Thereafter, the insulating layer 201 and the metal film 3001 are formed on one surface of the substrate 101 in this order at an area except the both end portions of the substrate 101 where the sprocket holes 10z are formed. Specifically, the semi-cured insulating layer 201 and the metal film 3001 are stacked on the one surface of the substrate 101 in this order and are heated so that the semi-cured insulating layer 201 is cured.
Each area C (referred to as the “individual areas C”) expressed by a dashed line inside the both end portions of the substrate 101 where the sprocket holes 10z are formed becomes the coil substrate 1 after finally being cut and individualized along the dashed lines. The plurality of individual areas C is aligned in columns and rows, for example. At this time, the plurality of individual areas C may be aligned with a predetermined space therebetween as illustrated in FIG. 4A, or may be aligned to contact with each other. Further, the number of individual areas C and the number of sprocket holes 10z may be arbitrarily determined. Here, a line expressed by “D” (hereinafter, referred to as cut position D) indicates a cut position along which the reel (tape) substrate 101 or the like is cut in the following step.
For the substrate 101, polyphenylenesulfide film, polyimide film, polyethylenenaphthalate film or the like may be used, for example. The thickness of the substrate 101 may be about 50 to 75 μm, for example.
For the insulating layer 201, film epoxy based insulating resin or the like may be used, for example. Alternatively, for the insulating layer 201, liquid or paste epoxy based insulating resin or the like may be used. The thickness of the insulating layer 201 may be about 8 to 12 μm, for example. The metal film 3001 becomes the metal layer 3011 and the connecting portion 35 after being patterned, and may be made of a copper film, for example. The thickness of the metal film 3001 may be about 12 to 50 μm, for example.
The sprocket holes 10z are used for pitch feeding the substrate 101 by being engaged with pins of a sprocket that is driven by a motor or the like when the substrate 101 is mounted on a manufacturing apparatus or the like in the course of manufacturing the coil substrate 1. The width (in a direction perpendicular to the alignment direction of the sprocket holes 10z (Y direction)) of the substrate 101 is determined to correspond to the manufacturing apparatus on which the substrate 101 is mounted.
The width of the substrate 101 may be about 40 to 90 mm, for example. On the other hand, the length of the substrate 101 (in an alignment direction of the sprocket holes 10z (X direction)) may be arbitrarily determined. For the example illustrated in FIG. 4A, there are individual areas C of 5 rows and 10 columns. However, the substrate 101 may be made longer and the individual areas C of about few hundreds columns may be provided, for example.
Next, in steps illustrated in FIG. 5A and FIG. 5B (FIG. 5B is a plan view and FIG. 5A is a cross-sectional view of FIG. 5B taken along an A-A line in FIG. 5B), the first structure 1A is formed in which metal layer 3011 is formed on the substrate 101. The metal layer 3011 becomes the first wiring 301 that is the first layer wiring and is a part (about a roll) of the coil after finally shaped (by die cutting or the like).
Specifically, the metal layer 3011 is formed on the insulating layer 201 by patterning the metal film 3001 illustrated in FIG. 4B. Further, at this time, the connecting portion 35 is formed at the one end portion of the metal layer 3011. Further, at this time, a bus line 36 connected to the connecting portion 35 is formed. The bus line 36 is used for power supply in electroplating in the following steps and is electrically connected to the metal layer 3011 and the connecting portion 35 of each of the individual areas C. If the electroplating is not performed in the following steps, the bus line 36 may not be formed. The metal layer 3011 is provided with a slit portion 301x. The slit portion 301x is provided to facilitate forming a spiral shape of the coil when shaping (die cutting or the like) the coil substrate 1.
The metal film 3001 may be patterned by photolithography, for example. This means that the metal film 3001 may be patterned by forming photosensitive resist on the metal film 3001, forming an open portion in the photosensitive resist by exposing and developing a predetermined area, and removing the metal film 3001 that is exposed in the open portion by etching. The metal layer 3011, the connecting portion 35 and the bus line 36 are integrally formed.
Thereafter, the metal layer 3011, the connecting portion 35 and the bus line 36 are covered by the insulating layer 401. The insulating layer 401 may be formed by laminating a film photosensitive epoxy based insulating resin or the like. Alternatively, the insulating layer 401 may be formed by coating liquid or paste photosensitive epoxy based insulating resin or the like. The thickness of the insulating layer 401 (the thickness from the upper surface of the metal layer 3011) may be about 5 to 30 μm, for example.
Thereafter, the open portion 4011 is formed in the insulating layer 401 of the first structure 1A that exposes the upper surface of the metal layer 3011. The plan shape of the open portion 4011 may be a circular shape whose diameter is about 150 μm. The open portion 4011 may be formed by press working, laser processing or the like, for example. The open portion 4011 may be formed by exposing and developing the photosensitive insulating layer 401. In FIG. 5B, the insulating layer 401 is not illustrated. In FIG. 5B, an area of the metal layer 3011 corresponding to the open portion 4011 is illustrated by a dashed line.
Next, in steps illustrated in FIG. 6A and FIG. 6B (FIG. 6B is a plan view and FIG. 6A is a cross-sectional view of FIG. 6B taken along an A-A line in FIG. 6B), the second structure 1B is formed in which the metal layer 3012 is formed on the substrate 102 (second substrate). The metal layer 3012 becomes the second wiring 302 that is the second layer wiring and is a part (about 3⁄4 roll) of the coil after finally shaped (by die cutting or the like). Specifically, after forming the sprocket holes 10z, similar to the step illustrated in FIG. 4A and FIG. 4B, the insulating layer 202 and the metal film 3002 (not illustrated in the drawings) are formed on the substrate 102 in this order at an area except the both end portions of the substrate 102 where the sprocket holes 10z are formed.
Then, similar to the steps illustrated in FIG. 5A and FIG. 5B, the metal film 3002 is patterned and the metal layer 3012 patterned as illustrated in FIG. 6B is formed on the insulating layer 202. Thereafter, the metal layer 3012 is covered by the insulating layer 402. Then, the open portion 1021 is formed in the substrate 102 and the insulating layer 202 of the second structure 1B that exposes the lower surface of the metal layer 3012. Further, the open portion 1022 (through hole) is formed that penetrates the substrate 102, and the insulating layer 202, the metal layer 3012 and the insulating layer 402 of the second structure 1B.
The plan shape of each of the open portions 1021 and 1022 may be a circular shape whose diameter is about 150 μm. The open portions 1021 and 1022 may be formed by press working, laser processing or the like. The open portion 1022 is formed at a position that overlaps the open portion 4011 in a plan view when the first structure 1A and the second structure 1B are stacked with each other in a predetermined direction. Further, in FIG. 6B, the insulating layer 402 is not illustrated. Further, in FIG. 6B, an area of the metal layer 3012 corresponding to the open portion 1021 is illustrated by a dashed line.
The shape, the thickness, the material and the like of the substrate 10n and the metal film 300n (here, “n” is a natural number more than or equal to 2) are the same as those of the substrate 101 and the metal film 3001 unless otherwise explained.
Next, steps illustrated in FIG. 7A to FIG. 7C are explained. FIG. 7A to FIG. 7C are cross-sectional views corresponding to FIG. 5A and FIG. 6A. First, in a step illustrated in FIG. 7A, the adhesion layer 501 is prepared and the open portion 5011 (through hole) that penetrates the adhesion layer 501 is formed. The open portion 5011 may be formed at a position that overlaps the open portions 4011 and 1022 in a plan view when the first structure 1A and the second structure 1B are stacked with each other through the adhesion layer 501 in the predetermined direction. For the adhesion layer 501, heat resistance adhesive (thermosetting) made of insulating resin such as epoxy based adhesive, polyimide based adhesive or the like may be used, for example. The thickness of the adhesion layer 501 may be about 10 to 40 μm, for example.
Next, the substrate 102 and the second structure 1B are reversed from the state illustrated in FIG. 6A, and are stacked on the first structure 1A through the adhesion layer 501. This means that the first structure 1A and the second structure 1B are faced to be stacked while interposing the adhesion layer 501 such that the substrate 101 and the substrate 102 are positioned outside. Thereafter, the adhesion layer 501 is cured. At this time, as the open portion 4011, the open portion 5011 and the open portion 1022 are in communication with each other, a single open portion 1023 is formed and the upper surface of the metal layer 3011 is exposed at a bottom portion.
Alternatively, in the steps illustrated in FIG. 6A to FIG. 7A, the second structure 1B may be stacked on the first structure 1A through the adhesion layer 501 before forming the open portions, and thereafter, the open portions 1021, 1022 and 5011 may be provided.
Next, in a step illustrated in FIG. 7B, the substrate 102 is removed (peeled) from the insulating layer 202 of the second structure 1B. The substrate 102 may be mechanically removed from the insulating layer 202 of the second structure 1B.
Next, in a step illustrated in FIG. 7C, the via wiring 601 made of copper (Cu) or the like, for example, is formed on the metal layer 3011 that is exposed at the bottom portion of the open portion 1023. The metal layer 3011 and the metal layer 3012 are electrically connected in series through the via wiring 601. Further, the via wiring 602 made of copper (Cu) or the like, for example, is formed on the metal layer 3012 that is exposed at a bottom portion of the open portion 1021. The metal layer 3012 and the via wiring 602 are electrically connected with each other.
The via wirings 601 and 602 may be formed by depositing copper (Cu) or the like from the metal layers 3011 and 3012 sides by electroplating in which the bus line 36 is used for supplying power, for example. Further, the via wirings 601 and 602 may be formed by filling metal paste of copper (Cu) or the like on the metal layer 3011 that is exposed at the bottom portion of the open portion 1023 and also filling the metal paste of copper (Cu) or the like on the metal layer 3012 that is exposed at the bottom portion of the open portion 1021. The upper surfaces of the via wirings 601 and 602 may be flush with the upper surface of the insulating layer 202. With this process, in the stacked structure in which the second structure 1B is stacked on the first structure 1A, the metal layer 3011, the via wiring 601 and the metal layer 3012 are electrically connected in series. Those connected parts become the coil of about one and 3⁄4 rolls after finally shaped (by die cutting or the like).
Next, in steps illustrated in FIG. 8A to FIG. 8C, similar to the steps illustrated in FIG. 6A and FIG. 6B, the third structure 1C is formed in which the metal layer 3013 is formed on the substrate 103. FIG. 8C is a plan view, FIG. 8A is a cross-sectional view of FIG. 8C taken along an A-A line in FIG. 8C and FIG. 8B is a cross-sectional view of FIG. 8C taken along an E-E line in FIG. 8C. The metal layer 3013 becomes the third wiring 303 that is the third layer wiring and is a part (about a roll) of the coil after finally shaped (by die cutting or the like). The metal layer 3013 is provided with a slit portion 301y. The slit portion 301y is provided to facilitate forming the spiral shape of the coil when shaping (die cutting or the like) the coil substrate 1 in the following step.
Next, the open portion 1031 is formed in the substrate 103 and the insulating layer 203 of the third structure 1C that exposes the lower surface of the metal layer 3013. Further, the open portion 1032 (through hole) is formed that penetrates the substrate 103, and the insulating layer 203, the metal layer 3013 and the insulating layer 403 of the third structure 1C.
The plan shape and the method of forming the open portions 1031 and 1032 may be the same as those of the open portion 1021 or the like, for example. The open portion 1032 is formed at a position that overlaps the open portion 1021 in a plan view when the second structure 1B and the third structure 1C are stacked with each other in the predetermined direction. The insulating layer 403 is not illustrated in FIG. 8C. Further, in FIG. 80, an area of the metal layer 3013 corresponding to the open portion 1031 is illustrated by a dashed line.
Next, steps illustrated in FIG. 9A to FIG. 9C are explained. FIG. 9A to FIG. 9C are cross-sectional views corresponding to FIG. 7C. First, in a step illustrated in FIG. 9A, the adhesion layer 502 is prepared and the open portion 5021 (through hole) that penetrates the adhesion layer 502 is formed. The open portion 5021 is formed at a position that overlaps the via wiring 602 in a plan view when the second structure 1B and the third structure 1C are stacked with each other through the adhesion layer 502 in the predetermined direction. The shape, the thickness, the material and the like of an adhesion layer 50n (here, “n” is a natural number more than or equal to 2) are the same as those of the adhesion layer 501 unless otherwise explained.
Next, the substrate 103 and the third structure 1C are reversed from the state illustrated in FIG. 8A, and are stacked on the second structure 1B through the adhesion layer 502. This means that the second structure 1B and the third structure 1C are faced to be stacked while interposing the adhesion layer 502 such that the substrate 101 and the substrate 103 are positioned outside. Thereafter, the adhesion layer 502 is cured. At this time, as the open portion 5021 and the open portion 1032 are in communication with each other, a single open portion 1033 is formed and the upper surface of the via wiring 602 is exposed at a bottom portion.
Alternatively, in the steps illustrated in FIG. 8A to FIG. 9A, the third structure 1C may be stacked on the second structure 1B through the adhesion layer 502 before forming the open portions, and thereafter, the open portions 1031, 1032 and 5021 may be provided.
Next, in a step illustrated in FIG. 9B, the substrate 103 is removed (peeled) from the insulating layer 203 of the third structure 1C.
Next, in a step illustrated in FIG. 9C, the via wiring 603 is formed on the via wiring 602 that is exposed at the bottom portion of the open portion 1033. The metal layer 3012 and the metal layer 3013 are electrically connected in series through the via wirings 602 and 603. Further, the via wiring 604 (not illustrated in the drawings) is formed on the metal layer 3013 that is exposed at the bottom portion of the open portion 1031 (not illustrated in the drawings). The metal layer 3013 and the via wiring 604 are electrically connected with each other.
The via wirings 603 and 604 may be formed by electroplating in which the bus line 36 is used for supplying power or by filling metal paste, similar to the via wiring 601. For the material of the via wirings 603 and 604, copper (Cu) or the like may be used, for example. The upper surfaces of the via wirings 603 and 604 may be flush with the upper surface of the insulating layer 203. With this process, in the stacked structure in which the first structure 1A to the third structure 1C are stacked, the metal layers 3011, 3012 and 3013 are electrically connected in series through the via wirings. Those connected parts become the coil of about two and 3⁄4 rolls after finally shaped (by die cutting or the like).
Next, in steps illustrated in FIG. 10A and FIG. 10B (FIG. 10B is a plan view and FIG. 10A is a cross-sectional view of FIG. 10B taken along an F-F line in FIG. 10B), similar to the steps illustrated in FIG. 6A and FIG. 6B, the fourth structure 1D is formed in which the metal layer 3014 is formed on the substrate 104. The metal layer 3014 becomes the fourth wiring 304 that is the fourth layer wiring and is a part (about 3⁄4 roll) of the coil after finally shaped (by die cutting or the like).
Next, the open portion 1041 is formed in the substrate 104 and the insulating layer 204 of the fourth structure 1D that exposes the lower surface of the metal layer 3014. Further, the open portion 1042 (through hole) is formed that penetrates the substrate 104, and the insulating layer 204, the metal layer 3014 and the insulating layer 404 of the fourth structure 1D.
The plan shape and the method of forming the open portions 1041 and 1042 may be the same as those of the open portion 1021 or the like. The open portion 1042 is formed at a position that overlaps the via wiring 604 in a plan view when the third structure 1C and the fourth structure 1D are stacked with each other in the predetermined direction. Here, the insulating layer 404 is not illustrated in FIG. 10B. Further, in FIG. 10B, an area corresponding to the open portion 1041 of the metal layer 3014 are illustrated by a dashed line.
Next, steps illustrated in FIG. 11A to FIG. 11C are explained. FIG. 11A to FIG. 11C are cross-sectional views corresponding to FIG. 9C and FIG. 10A. First, in a step illustrated in FIG. 11A, the adhesion layer 503 is prepared, and the open portion 5031 (through hole) that penetrates the adhesion layer 503 is formed. The open portion 5031 is formed at a position that overlaps the via wiring 604 in a plan view when the third structure 1C and the fourth structure 1D are stacked with each other through the adhesion layer 503 in the predetermined direction.
Next, the substrate 104 and the fourth structure 1D are reversed from the state illustrated in FIG. 10A, and are stacked on the third structure 1C through the adhesion layer 503. This means that the third structure 1C and the fourth structure 1D are faced to be stacked while interposing the adhesion layer 503 such that the substrate 101 and the substrate 104 are positioned outside. Thereafter, the adhesion layer 503 is cured. At this time, as the open portion 5031 and the open portion 1042 are in communication with each other, a single open portion 1043 is formed and the upper surface of the via wiring 604 is exposed at a bottom portion.
Alternatively, in the steps illustrated FIG. 10A to FIG. 11A, the fourth structure 1D may be stacked on the third structure 1C through the adhesion layer 503 before forming the open portions, and thereafter, the open portions 1041, 1042 and 5031 may be formed.
Next, in a step illustrated in FIG. 11B, the substrate 104 is removed (peeled) from the insulating layer 204 of the fourth structure 1D.
Next, in a step illustrated in FIG. 11C, the via wiring 605 is formed on the via wiring 604 that is exposed at the bottom portion of the open portion 1043. The metal layer 3013 and the metal layer 3014 are electrically connected in series through the via wirings 604 and 605. Further, the via wiring 606 is formed on the metal layer 3014 that is exposed at the bottom portion of the open portion 1041. The metal layer 3014 and the via wiring 606 are electrically connected with each other.
The via wirings 605 and 606 may be formed by electroplating in which the bus line 36 is used for supplying power or by filling metal paste, similar to the via wiring 601 or the like. For the material of the via wirings 605 and 605, copper (Cu) or the like may be used, for example. The upper surfaces of the via wirings 605 and 606 may be flush with the upper surface of the insulating layer 204. With this process, in the stacked structure in which the first structure 1A to the fourth structure 1D are stacked, the metal layers 3011, 3012, 3013 and 3014 are electrically connected in series through the via wirings. Those connected parts become the coil of about three rolls after finally shaped (by die cutting or the like).
Next, in steps illustrated in FIG. 12A to FIG. 12C, similar to the steps illustrated in FIG. 6A and FIG. 6B, the fifth structure 1E is formed in which the metal layer 3015 is formed on the substrate 105. FIG. 12C is a plan view, FIG. 12A is a cross-sectional view of FIG. 12C taken along an F-F line in FIG. 12C, and FIG. 12B is a cross-sectional view of FIG. 12C taken along a G-G line in FIG. 12C. The metal layer 3015 becomes the fifth wiring 305 that is the fifth layer wiring and a part (about a roll) of the coil after finally shaped (by die cutting or the like). The metal layer 3015 is provided with a slit portion 301y. The slit portion 301y is provided to facilitate forming the spiral shape of the coil when shaping (die cutting or the like) the coil substrate 1 in the following step.
Next, the open portion 1051 is formed in the substrate 105 and the insulating layer 205 of the fifth structure 1E that exposes the lower surface of the metal layer 3015. Further, the open portion 1052 (through hole) is formed that penetrates the substrate 105, and the insulating layer 205, the metal layer 3015 and the insulating layer 405 of the fifth structure 1E.
The plan shape and the method of forming the open portions 1051 and 1052 may be the same as those of the open portion 1021 or the like, for example. The open portion 1052 is formed at a position that overlaps the open portion 5041 in a plan view when the fourth structure 1D and the fifth structure 1E are stacked with each other in the predetermined direction. The insulating layer 405 is not illustrated in FIG. 12C. Further, in FIG. 12C, an area corresponding to the open portion 1051 of the metal layer 3015 is illustrated by a dashed line.
Next, steps illustrated in FIG. 13A to FIG. 13C are explained. FIG. 13A to FIG. 13C are cross-sectional views corresponding to FIG. 11C and FIG. 12A. First, in a step illustrated in FIG. 13A, the adhesion layer 504 is prepared and the open portion 5041 (through hole) that penetrates the adhesion layer 504 is formed. The open portion 5041 is formed at a position that overlaps the via wiring 606 in a plan view when the fourth structure 1D and the fifth structure 1E are stacked with each other through the adhesion layer 504 in the predetermined direction.
Next, the substrate 105 and the fifth structure 1E are reversed from the state illustrated in FIG. 12A, and are stacked on the fourth structure 1D vie the adhesion layer 504. This means that the fourth structure 1D and the fifth structure 1E are faced to be staked while interposing the adhesion layer 504 such that the substrate 101 and the substrate 105 are positioned outside. Thereafter, the adhesion layer 504 is cured. At this time, as the open portion 5041 and the open portion 1052 are in communication with each other, a single open portion 1053 is formed and the upper surface of the via wiring 606 is exposed at a bottom portion.
Alternatively, in the steps illustrated in FIG. 12A to FIG. 13A, the fifth structure 1E may be stacked on the fourth structure 1D through the adhesion layer 504 before forming the open portions, and thereafter, the open portions 1051, 1052 and 5041 may be formed.
Next, in a step illustrated in FIG. 13B, the substrate 105 is removed (peeled) from the insulating layer 205 of the fifth structure 1E.
Next, in a step illustrated in FIG. 13C, the via wiring 607 is formed on the via wiring 606 that is exposed at the bottom portion of the open portion 1053. The metal layer 3015 and the metal layer 3014 are electrically connected in series through the via wirings 606 and 607. Further, the via wiring 608 (not illustrated in the drawings) is formed on the metal layer 3015 that is exposed at the bottom portion of the open portion 1051 (not illustrated in the drawings). The metal layer 3015 and the via wiring 608 are electrically connected with each other.
The via wirings 607 and 608 may be formed by electroplating in which the bus line 36 is used for supplying power or by filling metal paste, similar to the via wiring 601 or the like. For the material of the via wirings 607 and 608, copper (Cu) or the like may be used, for example. The upper surfaces of the via wirings 607 and 608 may be flush with the upper surface of the insulating layer 205. With this process, in the stacked structure in which the first structure 1A to the fifth structure 1E are stacked, the metal layers 3011, 3012, 3013, 3014 and 3015 are electrically connected in series through the via wirings. Those connected parts become the coil of about four rolls after finally shaped (by die cutting or the like).
Next, steps illustrated in FIG. 14A to FIG. 14C are explained. FIG. 14A to FIG. 14C are cross-sectional views corresponding to FIG. 13C. First, in a step illustrated in FIG. 14A, the sixth structure 1F is formed in which the metal layer 3016 is formed on the substrate 106. The metal layer 3016 becomes the sixth wiring 306 that is the sixth layer wiring and is a part (about 3⁄4 roll) of the coil after finally shaped (by die cutting or the like). Then, the open portion 1061 is formed in the substrate 106 and the insulating layer 206 of the sixth structure 1F that exposes the lower surface of the metal layer 3016. Further, the open portion 1062 (through hole) is formed that penetrates the substrate 106, and the insulating layer 206, the metal layer 3016 and the insulating layer 406 of the sixth structure 1F. Although the reference numerals are different in the sixth structure 1F and the second structure 1B, the sixth structure 1F has the same structure as the second structure 1B and the open portions 1061 and 1062 respectively correspond to the open portions 1021 and 1022.
Next, the adhesion layer 505 is prepared and the open portion 5051 (through hole) is formed that penetrates the adhesion layer 505. The open portion 5051 is formed at a position that overlaps the via wiring 608 in a plan view when the sixth structure 1F and the fifth structure 1E are stacked with each other through the adhesion layer 505 in the predetermined direction. Then, similar to FIG. 7A, the substrate 106 and the sixth structure 1F are reversed from the state illustrated in FIG. 6A, and are stacked on the fifth structure 1E through the adhesion layer 505. This means that the fifth structure 1E and the sixth structure 1F are faced to be stacked while interposing the adhesion layer 505 such that the substrate 101 and the substrate 106 are positioned outside. Thereafter, the adhesion layer 505 is cured. At this time, as the open portion 5051 and the open portion 1062 are in communication with each other, a single open portion 1063 is formed and the upper surface of the via wiring 608 is exposed at a bottom portion.
Alternatively, in the steps illustrated in FIG. 6A, FIG. 6B and FIG. 14A, the sixth structure 1F may be stacked on the fifth structure 1E through the adhesion layer 505 before forming the open portions, and thereafter, the open portions 1061, 1062 and 5051 may be formed.
Next, in a step illustrated in FIG. 14B, the substrate 106 is removed (peeled) from the insulating layer 206 of the sixth structure 1F.
Next, in a step illustrated in FIG. 14C, the via wiring 609 is formed on the via wiring 608 that is exposed at the bottom portion of the open portion 1063. The metal layer 3015 and the metal layer 3016 are electrically connected in series through the via wirings 608 and 609. Further, the via wiring 6010 is formed on the metal layer 3016 that is exposed at the bottom portion of the open portion 1061. The metal layer 3016 and the via wiring 6010 are electrically connected with each other.
The via wirings 609 and 6010 may be formed by electroplating in which the bus line 36 is used for supplying power or by filling metal paste, similar to the via wiring 601 or the like. For the material of the via wirings 609 and 6010, copper (Cu) or the like may be used, for example. The upper surfaces of the via wirings 609 and 6010 may be flush with the upper surface of the insulating layer 206. With this process, in the stacked structure in which the first structure 1A to the sixth structure 1F are stacked, the metal layers 3011, 3012, 3013, 3014, 3015 and 3016 are electrically connected in series through the via wirings. Those connected parts become the coil of about four and 3⁄4 rolls after finally shaped (by die cutting or the like).
Next, in steps illustrated in FIG. 15A and FIG. 15B, similar to the steps illustrated in FIG. 6A and FIG. 6B, the seventh structure 1G is formed in which the metal layer 3017 is formed on the substrate 107. The metal layer 3017 becomes the seventh wiring 307 that is the seventh layer wiring and is a part (about a roll) of the coil after finally shaped (by die cutting or the like). Specifically, the metal layer 3017 is formed on the insulating layer 207. Further, the connecting portion 37 is formed at one end portion of the metal layer 3017. The metal layer 3017 and the connecting portion 37 are integrally formed. The metal layer 3017 is provided with a slit portion 301x. The slit portion 301x is provided to facilitate forming the spiral shape of the coil when shaping (die cutting or the like) the coil substrate 1 in the following step.
Next, the open portion 1072 (through hole) is formed that penetrates the substrate 107, and the insulating layer 207, the metal layer 3017 and the insulating layer 407 of the seventh structure 1G. FIG. 15B is a plan view and FIG. 15A is a cross-sectional view of FIG. 15B taken along an A-A line of FIG. 15B. The plan shape and the method of forming the open portion 1072 may be the same as those of the open portion 1021 or the like, for example. The open portion 1072 is formed at a position that overlaps the via wiring 6010 in a plan view when the sixth structure 1E and the seventh structure 1G are stacked with each other in the predetermined direction. The insulating layer 407 is not illustrated in FIG. 15B.
Next, steps illustrated in FIG. 16A to FIG. 16C are explained. FIG. 16A to FIG. 16C are cross-sectional views corresponding to FIG. 14C and FIG. 15A. First, in a step illustrated in FIG. 16A, the adhesion layer 506 is prepared and the open portion 5061 (through hole) that penetrates the adhesion layer 506 is formed. The open portion 5061 is formed at a position that overlaps the via wiring 6010 in a plan view when the sixth structure 1F and the seventh structure 1G are stacked with each other through the adhesion layer 506 in the predetermined direction.
Next, the substrate 107 and the seventh structure 1G are reversed from the state illustrated in FIG. 15A, and are stacked on the sixth structure 1F through the adhesion layer 506. This means that the sixth structure 1F and the seventh structure 1G are faced to be staked while interposing the adhesion layer 506 such that the substrate 101 and the substrate 107 are positioned outside. Thereafter, the adhesion layer 506 is cured. At this time, as the open portion 5061 and the open portion 1072 are in communication with each other, a single open portion 1073 is formed and the upper surface of the via wiring 6010 is exposed at a bottom portion.
Alternatively, in the steps illustrated in FIG. 15A to FIG. 16A, the seventh structure 1G may be stacked on the sixth structure 1F through the adhesion layer 506 before forming the open portions, and thereafter, the open portions 1072 and 5061 may be formed.
Next, in a step illustrated in FIG. 16B, the substrate 107 is removed (peeled) from the insulating layer 207 of the seventh structure 1G.
Next, in a step illustrated in FIG. 16C, the via wiring 6011 is formed on the via wiring 6010 that is exposed at the bottom portion of the open portion 1073. The metal layer 3016 and the metal layer 3017 are electrically connected in series through the via wirings 6010 and 6011.
The via wiring 6011 may be formed by electroplating in which the bus line 36 is used for supplying power or by filling metal paste, similar to the via wiring 601 or the like. For the material of the via wiring 6011, copper (Cu) or the like may be used, for example. The upper surface of the via wiring 6011 may be flush with the upper surface of the insulating layer 207. With this process, in the stacked structure in which the first structure 1A to the seventh structure 1G are stacked, the metal layers 3011, 3012, 3013, 3014, 3015, 3016 and 3017 are connected in series through the via wirings. Those connected parts become the coil of about five and 1⁄2 rolls after finally shaped (by die cutting or the like).
Next, in a step illustrated in FIG. 17A, the adhesion layer 507 is stacked on the seventh structure 1G in which an open portion is not provided. Next, in a step illustrated in FIG. 17B, the structure illustrated in FIG. 17A is individualized by being cut along the cut position D illustrated in FIG. 4A and FIG. 4B to form a substrates 1M. For the example illustrated in FIG. 17A and FIG. 17B, each of the substrates 1M includes 50 individual areas C. Alternatively, the step illustrated in FIG. 17B may not be performed and the reel (tape) structure for which the steps illustrated in FIG. 21A to FIG. 21C are performed may be shipped as a product.
Next, in steps illustrated in FIG. 18 to FIG. 21A, the substrate 1M is shaped (by die cutting or the like) to form the metal layer formed in each of the layers into the wiring that constitutes a part of the spiral-shaped coil by removing unnecessary parts. FIG. 18 is a plan view illustrating an example of the metal layer 3017 before die cutting or the like the substrate 1M (layers position upper than the metal layer 3017 are not illustrated). FIG. 19 is a perspective view schematically illustrating each metal layer formed in each of the layers before die cutting or the like the substrate 1M. The substrate 1M in which the metal layers as illustrated in FIG. 18 and FIG. 19 are shaped by press working using a die or the like to be in a form illustrated in FIG. 20 and FIG. 21A. FIG. 20 is a plan view corresponding to FIG. 18 and FIG. 21A is a cross-sectional view of FIG. 20 taken along an A-A line in FIG. 20. The shape of the wiring of each of the layers of the structure illustrated in FIG. 20 and FIG. 21A becomes such as illustrated in FIG. 2. The substrate 1M may be formed by laser processing or the like instead of press working using a die or the like.
With this process, in the stacked structure in which the first structure 1A to the seventh structure 1G are stacked, the metal layer 3011 is shaped to become the first wiring 301. Similarly, the metal layers 3012, 3013, 3014, 3015, 3016 and 3017 are shaped to become the second wiring 302, the third wiring 303, the fourth wiring 304, the fifth wiring 305, sixth wiring 306 and the seventh wiring 307, respectively. The first wiring 301, the second wiring 302, the third wiring 303, the fourth wiring 304, the fifth wiring 305, the sixth wiring 306 and the seventh wiring 307 are electrically connected in series through the via wirings to constitute the spiral-shaped coil of about 5 and 1⁄2 rolls.
The stacked structured in each of which the first structure 1A to the seventh structure 1G are stacked are formed in the individual areas C, respectively, and are connected (not electrically connected) through linking portions 80 including the insulating layer 407 or the like formed between the adjacent individual areas C. The insulating layer 407 or the like that constitutes the stacked structure of each of the individual areas C also has the substantially the same shape as the wiring and the through hole 1x that penetrates the layers is formed at a substantially center portion of each of the stacked structures.
Next, in steps illustrated in FIG. 21B, the insulating film 70 is formed so as to cover the surfaces of the stacked structure in which the first structure 1A to the seventh structure 1G are stacked except the bottom surface. This means that the insulating film 70 is formed that continuously covers the outer wall surface (sidewall) of the stacked structure formed at each of the individual areas C, the upper surface of the adhesion layer 507 and the inner wall surface of the through hole 1x (see FIG. 10 for plan shape). As the end surfaces of the wirings are exposed at the outer wall surface (sidewall) of the stacked structure or at the inner wall surface of the through hole 1x, there is a possibility that short between the wirings and the conductive material (magnetic filler or the like) that may be included in the sealing resin 110 may occur when the inductor 100 (see FIG. 3) is manufactured. Thus, by forming the insulating film 70 at surfaces of the stacked structure, the short between the wirings and the conductive material (magnetic filler or the like) that may be included in the sealing resin 110 is prevented.
For the insulating film 70, epoxy based insulating resin, acrylic based insulating resin or the like may be used, for example. The insulating film 70 may include filler such as silica or the like, for example. The insulating film 70 may be formed by spin coating, spray coating or the like, for example. Electrodepositing resist may be used as the insulating film 70. In this case, the electrodepositing resist is deposited only on the end surfaces of the wirings that are exposed at the outer wall surface (sidewall) of the stacked structure or the inner wall surface of the through hole 1x by electrodeposition coating. The thickness of the insulating film 70 may be about 20 to 50 μm, for example.
Next, in a step illustrated in FIG. 21C, the substrate 101 is removed from the insulating layer 201. With this, the coil substrate 1 (see FIG. 1A to FIG. 10) is formed in each of the individual areas C. The coil substrates 1 at the adjacent individual areas C are connected (not electrically connected) with each other through the linking portion 80 that is formed between those adjacent individual areas C.
In order to manufacture the inductor 100 (see FIG. 3), as illustrated in FIG. 22A, the coil substrates 1 illustrated in FIG. 21C are cut for each of the individual areas C, for example. With this, the linking portions 80 are removed and the individualized plurality of coil substrates 1 are formed. At this time, the side surface of the connecting portion 35 is exposed at the one side surface 1y and the side surface of the connecting portion 37 is exposed at the other side surface 1z, of each of the coil substrates 1.
Next, as illustrated in FIG. 22B, the sealing resin 110 is formed to seal the coil substrate 1 except the one side surface 1y and the side surface 1z by transfer mold or the like, for example. For the sealing resin 110, insulating resin such as epoxy based insulating resin or the like including magnetic filler such as ferrite or the like may be used, for example. Alternatively, the sealing resin 110 may be formed for the entirety of the individual areas C where the coil substrates 1 which are connected with each other through the linking portions 80 are formed as illustrated in FIG. 21C, and then, the coil substrates 1 may be cut to with the sealing resin 110 for each of the individual areas C to form the structure illustrated in FIG. 22B.
Next, as illustrated in FIG. 22C, the electrode 120 composed of copper (Cu) or the like that continuously covers the one side surface and parts of the upper surface and the lower surface of the sealing resin 110 is formed by plating or paste coating. The inner wall surface of the electrode 120 contacts the side surface of the connecting portion 35 that is exposed from the one side surface 1y of the coil substrate 1 so that the electrode 120 and the connecting portion 35 are electrically connected. Similarly, the electrode 130 composed of copper (Cu) or the like that continuously covers the other side surface and parts of the upper surface and the lower surface of the sealing resin 110 is formed by plating or paste coating. The inner wall surface of the electrode 130 contacts the side surface of the connecting portion 37 that is exposed from the other side surface 1z of the coil substrate 1 so that the electrode 130 and the connecting portion 37 are electrically connected. With this, the inductor 100 is completed.
As such, according to the coil substrate 1 of the embodiment, a single spiral-shaped coil is formed by manufacturing a plurality of structures in each of which a wiring that becomes a part of the spiral-shaped coil is covered by an insulating film, and stacking the structures through adhesion layers, respectively, such that the wirings of the structures are connected in series through via wirings, respectively. With this, by increasing the stacking number of the structures, a coil with the desired number of rolls can be obtained without changing the plan shape. This means that the number of rolls (the number of turns) of the coil can be increased with a size smaller (the plan shape of about 1.6 mm×0.8 mm, for example) than conventional coils.
Further, for example, a method may be considered in which a wiring that constitutes a part of a coil is previously patterned in each structure, and then the structures are stacked. However, in such a method, there may be shifts between the wirings of the structures in a leftward/rightward direction so that the wirings may not be stacked to completely overlap with each other in a plan view. Then, when a through hole or the like is formed in the stacked structure, a part of the wirings, which may be shifted with each other, may be removed. This kind of problem may be resolved by making the width of each of the wirings, which is previously formed in the respective structure, smaller in order to ensure areas where the wirings are not formed. However, in such a case, direct current resistance of the coil may be increased.
On the other hand, according to the method of manufacturing the coil substrate of the embodiment, a metal layer having a plan shape larger than that of a wiring of a final product is formed in each structure, a stacked structure is formed by stacking the structures, and the stacked structure is shaped in the thickness direction such as to form the metal layers into the shape of wirings each having a shape to constitute the spiral-shaped coil at the same time. Thus, the wirings are not shifted in the leftward/rightward direction, and the spiral-shaped coil can be obtained by the wirings that are stacked to high accurately overlap with each other in a plan view. As a result, direct current resistance can be decreased. This means that each of the wirings can be made wider so that the direct current resistance can be decreased as there is no need to worry about the shifts of the wirings in the leftward/rightward direction.
Further, as the number of rolls of the coil can be increased by increasing the stacking number of the structures without changing the plan shape, a small-size coil substrate with larger inductance can be easily obtained.
Further, a width of a wiring that is formed in each structure (one layer) can be made wider because the number of rolls of the wiring that is formed in each of the structures (one layer) is less than or equal to one of the coil. Thus, it is possible to increase the cross section of the wiring in the width direction, and winding resistance that influences performance of the inductor can be decreased.
Further, although the flexible insulating resin film (polyphenylenesulfide film or the like, for example) is used as the substrate 10n when manufacturing the coil substrate 1, the substrate 10n is removed and does not remain in a final product. Thus, the coil substrate 1 can be made thinner.
Further, by using a reel (tape) flexible insulating resin film (polyphenylenesulfide film or the like, for example) as the substrate 10n, the coil substrate 1 can be formed on the substrate 10n in a reel to reel process. With this, the cost for manufacturing the coil substrate 1 can be reduced due to mass production.
According to the embodiment, a smaller coil substrate or the like can be provided.
Although a preferred embodiment of the coil substrate, the method of manufacturing the coil substrate and the inductor has been specifically illustrated and described, it is to be understood that minor modifications may be made therein without departing from the spirit and scope of the invention as defined by the claims.
The present invention is not limited to the specifically disclosed embodiments, and numerous variations and modifications may be made without departing from the spirit and scope of the present invention.
For example, a combination of the number of rolls that each wiring (one layer) of each of a plurality of structures has, may be arbitrarily determined. For example, a combination of the wirings of about one roll and the wirings of about 3⁄4 roll may be used as the above explained embodiment, or alternatively, a combination of wirings of about one roll and wirings of about 1⁄2 roll may be used. When the wirings of about 3⁄4 roll are used, 4 kinds of pattern of wirings (the second wiring 302, the third wiring 303, the fourth wiring 304 and the fifth wiring 305, for example) are necessary. However, when the wirings of about 1⁄2 roll are used, only two kinds of pattern of wirings are necessary.
Further, in the above embodiment, “electrically connected in series” means that each of the wirings is connected to a first wiring that is included in an adjacent lower structure, for example, at one end, and is connected to a second wiring that is included in an adjacent upper structure, for example, at another end. Specifically, with reference to FIG. 2, one end (where the open portion 1022 is formed) of the second wiring 302 is connected to the first wiring 301 while another end (where the via wirings 602 and 603 are formed) of the second wiring 302 is connected to the third wiring 303.

## Claims

1. A method of manufacturing a coil substrate, comprising:
forming a plurality of structures, each of the structures including a first insulating layer and a metal layer formed on the first insulating layer;
forming a stacked structure by stacking the structures while connecting the metal layers of the adjacent structures in series; and
shaping the stacked structure such that the metal layers of the structures are shaped at the same time to be in shapes of wirings, each becomes a part of a spiral-shaped coil, to form the spiral-shaped coil in which the wirings of the adjacent structures are connected in series,
wherein in the shaping, unnecessary parts of each of the structures are removed at the same time such that an outer shape of each of the metal layers is shaped at the same time and a through hole around which the spiral-shaped coil is formed is provided among the metal layers at the same time.

2. The method of manufacturing the coil substrate according to claim 1,
wherein in the forming the plurality of structures, each of the structures is formed to include the first insulating layer, the metal layer formed on the first insulating layer and a second insulating layer formed on the first insulating layer such as to cover the metal layer.

3. The method of manufacturing the coil substrate according to claim 1,
wherein the forming the plurality of structures includes
forming a first structure on a first substrate, and
forming a second structure on a second substrate, and

wherein the forming the stacked structure includes
facing the first structure and the second structure to be stacked such that the first substrate and the second substrate are positioned outside,

removing the second substrate, and
connecting the metal layer of the first structure and the metal layer of the second structure in series.

4. The method of manufacturing the coil substrate according to claim 1,
wherein in the shaping the stacked structure, the stacked structure is shaped by press working.

5. The method of manufacturing the coil substrate according to claim 1,
wherein in the shaping the stacked structure, the stacked structure is shaped by laser processing.

6. The method of manufacturing the coil substrate according to claim 1, further comprising:
after the shaping the stacked structure, forming an insulating film that covers surfaces of the stacked structure.

7. The method of manufacturing the coil substrate according to claim 6,
wherein the insulating film is formed so as to cover the end surfaces of the wirings exposed in the shaping.

8. The method of manufacturing the coil substrate according to claim 6,
wherein the insulating film is made of insulating resin.

9. The method of manufacturing the coil substrate according to claim 6,
wherein the insulating film is formed by electrodeposition coating.

10. The method of manufacturing the coil substrate according to claim 1,
wherein in the shaping the stacked structure, the spiral-shaped coil and a linking portion that supports the spiral-shaped coil are formed.

11. The method of manufacturing the coil substrate according to claim 1,
wherein the stacked structure is formed to include a plurality of individual areas, and
wherein in the shaping the stacked structure, a plurality of the spiral-shaped coils in the plurality of individual areas, respectively, and a linking portion that supports and links the plurality of spiral-shaped coils are formed.

12. The method of manufacturing the coil substrate according to claim 1,
wherein the first insulating layer is made of insulating resin.

13. The method of manufacturing the coil substrate according to claim 1,
wherein in the shaping, unnecessary parts of the first insulating layer and the metal layer of each of the structures are removed.

14. A method of manufacturing an inductor comprising:
providing a component including a magnetic material in the through hole of the coil substrate according to claim 1; and
forming a first electrode and a second electrode that are connected to one end and the other end of the spiral-shaped coil respectively.

15. A method of manufacturing an inductor comprising:
cutting the linking portion of the coil substrate according to claim 11 so as to expose one end and the other end of each of the spiral-shaped coils; and
forming a first electrode and a second electrode that are connected to the one end and the other end of each of the spiral-shaped coils respectively.