Printed coil board and method for manufacturing printed coil board

Abstract

To provide a printed coil board including a coil which is suppressed from becoming larger and has an improved performance, and a method for manufacturing the printed coil board.SOLUTION: A printed coil board 100 includes: a round core layer 10 having a first main surface and a second main surface facing opposite directions; a first insulating layer 20 covering the core layer 10; and a conductor layer 30 having a seamless spiral shape, surrounding the core layer on the first insulating layer 20. At least a part in the region above at least one of the first main surface and the second main surface, of the conductor layer 30 has a width which gradually becomes larger from the inner side to the outer side of the core layer.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a printed coil board and a method for manufacturing a printed coil board. [Background technology]

[0002] In recent years, there has been a demand for thinner cored coils in which a conductor is wound around a magnetic body. Patent Document 1 describes a cored coil having a magnetic core and a coil wound around the magnetic core, characterized in that the coil is formed of multiple conductive plates, and the front end of one adjacent conductive plate is joined to the rear end of the other conductive plate, and this is repeated along the magnetic core, forming a conductive path formed by the conductive plates in a spiral shape around the magnetic core. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-329866 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the cored coil described in Patent Document 1, a spiral conductive path is formed around the magnetic core by connecting both ends of the conductive plate. When the magnetic core is annular, both ends of the conductive plate are connected at its inner peripheral surface. For this reason, the number of turns of the coil is limited by the size of the connection part. The smaller the inner diameter of the inner peripheral surface, the fewer the number of turns of the coil, so there is a limit to how small the coil can be. In addition, electrical resistance may change at the connection part of the conductive plate.

[0005] An object of the present invention is to provide a printed coil board including a coil with improved performance while preventing an increase in size, and a method for manufacturing the printed coil board. [Means for solving the problem]

[0006] A printed coil board according to one aspect of the present invention comprises an annular core layer having first and second main surfaces facing oppositely, a first insulating layer covering the core layer, and a conductor layer having a seamless spiral shape and surrounding the core layer on the first insulating layer, wherein the width of at least a portion of the conductor layer above at least one of the first and second main surfaces gradually increases in a direction from the inside to the outside of the core layer.

[0007] A method of manufacturing a printed coil board according to another aspect of the present invention includes the steps of: preparing a magnetic layer having a first main surface and a second main surface facing opposite to each other; forming an insulating layer on the first main surface of the magnetic layer; forming a core layer having a circular ring shape by removing a predetermined region of the magnetic layer; the core layer having the first main surface, the second main surface, an inner side surface connecting the first main surface and the second main surface and located inward, and an outer side surface connecting the first main surface and the second main surface and located outward; forming another insulating layer on the one insulating layer and on the second main surface, the inner side surface and the outer side surface of the core layer; the step of forming a plurality of outer holes through the first insulating layer and the other insulating layer at a position spaced inward from the core layer, and a central hole penetrating the first insulating layer and the other insulating layer; forming a conductor layer on the first insulating layer and the other insulating layer, passing through the central hole and each of the plurality of outer holes and spirally surrounding the core layer, the conductor layer including a first conductor portion located on the first main surface of the core layer and a second conductor portion located on the second main surface of the core layer, the width of at least a portion of at least one of the first conductor portion and the second conductor portion gradually increasing in a direction from the inside to the outside of the core layer; and cutting the first insulating layer and the other insulating layer along a cutting line connecting two adjacent ones of the plurality of outer holes. Effect of the Invention

[0008] According to the present invention, it is possible to provide a printed coil board including a coil with improved performance while preventing an increase in size, and a method for manufacturing the printed coil board. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view of a printed coil board according to an embodiment. [Diagram 2] 2 is a cross-sectional view taken along line AA in FIG. 1. [Diagram 3] FIG. 2 is a cross-sectional view taken along line BB in FIG. [Figure 4] FIG. 2 is a perspective view of the printed coil board as viewed from the outside of the core layer. [Diagram 5] FIG. 2 is a perspective view of the printed coil board as viewed from the inside of the core layer. [Figure 6] FIG. 1 is a side view showing an example of a roll-to-roll apparatus used in the manufacturing process of a printed coil board. [Figure 7] 4 is a flowchart showing a process sequence of a manufacturing method for a printed coil board. [Figure 8] FIG. 2 is a cross-sectional view of a printed coil board prepared in a first step. [Figure 9] FIG. 11 is a cross-sectional view of the printed coil board in a second step. [Figure 10] FIG. 11 is a cross-sectional view of the printed coil board in a third step. [Figure 11] FIG. 11 is a bottom view of the printed coil board in a third step. [Figure 12] FIG. 11 is a cross-sectional view of the printed coil board in a fourth step. [Figure 13] FIG. 11 is a cross-sectional view of the printed coil board in a fifth step. [Figure 14] FIG. 13 is a bottom view of the printed coil board in a fifth step. [Figure 15] FIG. 13 is a plan view of the printed coil board in a sixth step. [Figure 16] FIG. 13 is a bottom view of the printed coil board in a sixth step. [Figure 17]FIG. 13 is a cross-sectional view of the printed coil board in a seventh step. [Figure 18] FIG. 13 is a plan view of the printed coil board in a seventh step. [Figure 19] FIG. 13 is a bottom view of the printed coil board in a seventh step. [Figure 20] FIG. 13 is a cross-sectional view of the printed coil board in an eighth step. [Figure 21] FIG. 13 is a plan view of the printed coil board in an eighth step. [Figure 22] FIG. 11 is a first diagram for explaining a method for manufacturing a printed coil board in a modified example. [Figure 23] FIG. 11 is a second diagram for explaining the method for manufacturing the printed coil board in the modified example. [Figure 24] FIG. 11 is a perspective view of a printed coil board used in a comparative example. [Diagram 25] FIG. 11 is a diagram showing a change in resistance value R of a printed coil board in a comparative example. [Figure 26] FIG. 11 is a diagram showing changes in the value of inductance L of a printed coil board in a comparative example. [Figure 27] FIG. 11 is a diagram showing a change in the Q value of a printed coil board in a comparative example. [Figure 28] FIG. 13 is a plan view of a printed coil board according to another embodiment. [Figure 29] FIG. 13 is a diagram showing a simulation result in another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (1) Printed coil board A printed coil board according to an embodiment of the present invention will be described in detail below with reference to the drawings. Fig. 1 is a perspective view of a printed coil board according to an embodiment. Fig. 2 is a cross-sectional view taken along line AA in Fig. 1. Fig. 3 is a cross-sectional view taken along line BB in Fig. 1. With reference to Figs. 1, 2 and 3, a printed coil board 100 includes a core layer 10, a first insulating layer 20, a conductor layer 30, a second insulating layer 40, and external terminals IT and OT. Note that the second insulating layer 40 is omitted from Figs. 1 and 3.

[0011] As shown by the dotted line in FIG. 1, the core layer 10 has a circular ring shape in plan view and a flattened cylindrical shape. The core layer 10 has an upper surface 10a and a lower surface 10b, an outer side surface 10c, and an inner side surface 10d that face opposite to each other. The upper surface 10a and the lower surface 10b are circular ring shapes. The outer side surface 10c is the outer peripheral surface of the cylindrical core layer 10 and connects the upper surface 10a and the lower surface 10b. The inner side surface 10d is the inner peripheral surface of the cylindrical core layer 10 and connects the upper surface 10a and the lower surface 10b. The shape of the core layer 10 is not limited to a cylindrical shape, and may be annular in plan view, for example, a rectangular ring shape.

[0012] The core layer 10 is made of a magnetic material. The higher the relative magnetic permeability of the core layer 10, the better. The core layer 10 is preferably made of a soft magnetic material. For example, the core layer 10 is made of an electromagnetic steel plate, a silicon steel plate, iron, permalloy, or the like. The thickness t1 in the vertical direction of the core layer 10 is, for example, 10 μm or more and 500 μm or less, and the length l1 in the radial direction of the core layer 10 is preferably 50 μm or more and 3000 μm or less. In the core layer 10 of this embodiment, the length l1 in the radial direction is greater than the thickness t1 in the vertical direction. In this embodiment, the thickness t1 is 100 μm, and the length l1 in the radial direction is 450 μm.

[0013] The first insulating layer 20 surrounds the surface of the core layer 10. Specifically, the first insulating layer 20 covers the upper surface 10a, the lower surface 10b, the outer side surface 10c, and the inner side surface 10d of the core layer 10. The first insulating layer 20 is formed of a resin such as polyimide. The first insulating layer 20 may be formed of other resins such as acrylic resin, polyethernitrile resin, polyethersulfone resin, epoxy resin, polyethylene terephthalate resin, polyethylene naphthalate resin, or polyvinyl chloride resin.

[0014] The first insulating layer 20 includes a first insulating portion 20a on the upper surface 10a of the core layer 10, a second insulating portion 20b on the lower surface 10b of the core layer 10, a third insulating portion 20c on the outer side surface 10c of the core layer 10, and a fourth insulating portion 20d on the inner side surface 10d of the core layer 10. The thickness t2a of the first insulating portion 20a and the thickness t2b of the second insulating portion 20b are preferably 2 μm or more and 30 μm or less. In this embodiment, the thickness t2a of the first insulating portion 20a and the thickness t2b of the second insulating portion 20b are substantially equal to each other and are each 8 μm. The thickness t2c of the third insulating portion 20c and the thickness t2d of the fourth insulating portion 20d are set to any thickness. The thickness is determined by the accuracy of the drilling process described later, and the thinner the thickness, the more preferable. Hereinafter, the portion of the first insulating layer 20 located outward from the core layer 10 in plan view will be referred to as an outer annular portion 20Z, and the portion of the first insulating layer 20 located inward from the core layer 10 will be referred to as an inner annular portion 20Y.

[0015] The first insulating layer 20 and the core layer 10 are in direct contact with each other. Specifically, the first insulating portion 20a is in contact with the upper surface 10a of the core layer 10, the second insulating portion 20b is in contact with the lower surface 10b of the core layer 10, the third insulating portion 20c is in contact with the outer side surface 10c of the core layer 10, and the fourth insulating portion 20d is in contact with the inner side surface 10d of the core layer 10.

[0016] The conductor layer 30 has a seamless spiral shape and is disposed on the first insulating layer 20 so as to surround the core layer 10. The conductor layer 30 is formed simultaneously by electrolytic plating. Therefore, the conductor layer 30 is an integral body formed of the same metal. The conductor layer 30 has a plurality of first conductor parts 31 located on the upper surface 10a side of the core layer 10, a plurality of second conductor parts 32 located on the lower surface 10b side of the core layer 10, a plurality of third conductor parts 33 located outside the core layer 10, and a plurality of fourth conductor parts 34 located inside the core layer 10.

[0017] Each of the multiple third conductor portions 33 connects one of the multiple first conductor portions 31 to one of the multiple second conductor portions 32. Each of the multiple fourth conductor portions 34 connects one of the multiple first conductor portions 31 to one of the multiple second conductor portions 32. The third conductor portion 33 and the fourth conductor portion 34 connected to one first conductor portion 31 are each connected to two different second conductor portions 32 of the multiple second conductor portions 32. The third conductor portion 33 and the fourth conductor portion 34 connected to one second conductor portion 32 are each connected to two different first conductor portions 31 of the multiple first conductor portions 31.

[0018] The wiring core layer 10Z is disposed outside the core layer 10. The material of the wiring core layer 10Z is the same as that of the core layer 10. The wiring core layer 10Z is covered with a first insulating layer 20. A hole penetrating in the vertical direction is formed in a part of the wiring core layer 10Z. The first insulating layer 20 is disposed in the space inside the hole formed in the wiring core layer 10Z. The first insulating layer 20 disposed in the space inside the hole formed in the wiring core layer 10Z has a through hole h2 penetrating in the vertical direction. A wiring CL1 and an external terminal IT are disposed on the first insulating layer 20 above the wiring core layer 10Z. An external terminal OT is disposed on the first insulating layer 20 disposed in the space inside the hole formed in the wiring core layer 10Z, and a wiring CL2 is disposed on the first insulating layer 20 below the wiring core layer 10Z. The wiring CL2 is connected to the external terminal OT through the through hole h2.

[0019] Both ends of the conductor layer 30 are connected to the external terminal IT and the external terminal OT, respectively. A start end 30A of the plurality of first conductor portions 31, which corresponds to an end of the conductor layer 30, is connected to the external terminal IT via a wiring CL1 without being connected to any of the plurality of fourth conductor portions 34. A terminal end 30B of the plurality of second conductor portions 32, which corresponds to an end of the conductor layer 30, is connected to the external terminal OT via a wiring CL2 without being connected to any of the plurality of fourth conductor portions 34. In the printed coil board 100 of this embodiment, the conductor layer 30, the wirings CL1 and CL2, and the external terminals IT and OT are simultaneously formed on the first insulating layer 20 by electrolytic plating.

[0020] The conductor layer 30 is an alloy containing one or more of the following metals: copper, gold, silver, platinum, lead, tin, nickel, cobalt, indium, rhodium, chromium, tungsten, ruthenium, etc. The conductor layer 30 is made of a single material. In other words, the conductor layer 30 is made of a single metal or alloy. A seed layer may be disposed between the conductor layer 30 and the first insulating layer 20. The seed layer is a metal or alloy containing one or more of the following metals: copper, gold, silver, platinum, lead, tin, nickel, cobalt, indium, rhodium, chromium, tungsten, ruthenium, etc. The seed layer is made of a single material. In other words, the seed layer is made of a single metal or alloy.

[0021] When the seed layer is made of the same material as the conductor layer 30, the seed layer becomes a part of the conductor layer 30. In this case, the first insulating layer 20 and the conductor layer 30 are in direct contact with each other. The first insulating portion 20a contacts the first conductor portion 31, the second insulating portion 20b contacts the second conductor portion 32, the third insulating portion 20c contacts the third conductor portion 33, and the fourth insulating portion 20d contacts the fourth conductor portion 34. Therefore, only the first insulating layer 20 exists between the conductor layer 30 and the core layer 10.

[0022] On the other hand, when the seed layer is formed of a material different from the conductor layer 30, the seed layer is a separate part from the conductor layer 30, but like the conductor layer 30, the seed layer has a seamless spiral shape and surrounds the core layer 10 on the first insulating layer 20. The seed layer is made of the same metal or alloy and is formed at the same time. Therefore, only the seed layer and the first insulating layer 20 exist between the conductor layer 30 and the core layer 10, and only the first insulating layer exists between the seed layer and the core layer 10. Since the seed layer is a conductor through which a current flows, even if it is formed of a material different from the conductor layer 30, it has the same function as the conductor layer 30 in that it is formed of a material that flows a current. Therefore, only the first insulating layer 20 exists between the conductor and the core layer 10.

[0023] The thickness t3a of the first conductor portion 31, the thickness t3b of the second conductor portion 32, the thickness t3c of the third conductor portion 33, and the thickness t3d of the fourth conductor portion 34 of the conductor layer 30 are preferably 2 μm or more and 500 μm or less. In the present embodiment, the thickness t3a of the first conductor portion 31, the thickness t3b of the second conductor portion 32, the thickness t3c of the third conductor portion 33, and the thickness t3d of the fourth conductor portion 34 are substantially equal to each other, that is, 25 μm.

[0024] The second insulating layer 40 surrounds the core layer 10 from the upper surface of the conductor layer 30. The second insulating layer 40 includes a second insulating portion 40a located on the upper surface 10a of the core layer 10, a second insulating portion 40b located on the lower surface 10b of the core layer 10, a second insulating portion 40c located on the outer side surface 10c of the core layer 10, and a second insulating portion 40d located on the inner side surface 10d of the core layer 10. The thickness t4a of the second insulating portion 40a, the thickness t4b of the second insulating portion 40b, the thickness t4c of the second insulating portion 40c, and the thickness t4d of the second insulating portion 40d are preferably 2 μm or more and 30 μm or less. In this embodiment, the thickness t4a of the second insulating portion 40a, the thickness t4b of the second insulating portion 40b, the thickness t4c of the second insulating portion 40c, and the thickness t4d of the second insulating portion 40d are substantially equal to each other and are each 6 μm. The thickness t10 in the vertical direction of the printed coil substrate 100 is 20 μm or more and 1.0 mm or less. In this embodiment, the thickness t10 of the printed coil substrate 100 is represented by the sum of the thickness t1, the thickness t2a, the thickness t2b, the thickness t3a, the thickness t3b, the thickness t4a, and the thickness t4b, and is 178 μm.

[0025] FIG. 4 is a first perspective view showing an enlarged portion of the printed coil board. FIG. 5 is a second perspective view showing an enlarged portion of the printed coil board. FIGS. 4 and 5 are enlarged views of a portion P of the printed coil board 100 in FIG. 1. In addition, in FIGS. 4 and 5, the core layer 10 is indicated by a dashed line. FIG. 4 is a perspective view of the printed coil board 100 as viewed from the outside of the core layer 10. FIG. 5 is a perspective view of the printed coil board 100 as viewed from the inside of the core layer 10.

[0026] The width of each of the multiple first conductor parts 31 gradually increases from the inner side surface 10d to the outer side surface 10c of the core layer 10. Here, the width of each of the multiple first conductor parts 31 is the distance between two points where the outer circumference of the first conductor part 31 intersects with the outer circumference of a circle centered on the rotation symmetric axis of the core layer 10. In other words, for the width w1 of each of the multiple first conductor parts 31, the width of the outer part of the core layer 10 is longer than the width of the part located inside. The width of each of the multiple second conductor parts 32 gradually increases from the inner side surface 10d to the outer side surface 10c of the core layer 10. Here, the width of each of the multiple second conductor parts 32 is the distance between two points where the outer circumference of the second conductor part 32 intersects with the outer circumference of a circle centered on the rotation symmetric axis of the core layer 10. In other words, for the width w2 of each of the multiple second conductor parts 32, the width of the outer part of the core layer 10 is longer than the width of the part located inside.

[0027] With reference to FIG. 4, a plurality of outer peripheral recesses 22 are formed on the outer side surface 21 of the outer annular portion 20Z, and are arranged in the circumferential direction. A plurality of third conductors 33 are arranged in the plurality of outer peripheral recesses 22 formed on the outer side surface 21 of the outer annular portion 20Z. Since two adjacent third conductors 33 are formed in two adjacent outer peripheral recesses 22, they are separated by the outer side surface 21 located between the two outer peripheral recesses 22. With reference to FIG. 5, a plurality of fourth conductors 34 are arranged on the inner side surface of the inner annular portion 20Y. Each of the plurality of fourth conductors 34 connects one of the plurality of first conductors 31 and one of the plurality of second conductors 32. The inner side surface 34a of the fourth conductor 34 in this embodiment is seamless.

[0028] (2) Manufacturing Method of Printed Coil Board 100 6 is a side view showing an example of a roll-to-roll apparatus used in the manufacturing process of the printed coil substrate 100. In this embodiment, the printed coil substrate 100 is manufactured by the roll-to-roll method. As shown in FIG. 6, the roll-to-roll apparatus 500 includes an unwinding section 501, a winding section 502, and a plurality of processing sections 510-1, 510-2, ..., 510-N (N is an integer of 3 or more). First, a feed roll RR1 around which a long sheet 10A made of a ferromagnetic material is wound is prepared and set in the unwinding section 501 of the roll-to-roll apparatus 500.

[0029] The sheet 10A is fed from a prepared feed roll RR1. The fed sheet 10A is taken up by another roll (take-up roll) R2 set in a take-up section 502, as indicated by the dotted arrow in FIG.

[0030] In the roll-to-roll apparatus 500, a plurality of processing sections 510-1, 510-2, ..., 510-N are arranged between two rolls (RR1, RR2) so as to be aligned along the moving direction of the sheet 10A. The plurality of processing sections 510-1, 510-2, ..., 510-N perform various processes on the long sheet 10A moving between the two rolls (RR1, RR2). As a result, N types of processes are performed on the sheet 10A taken up by the take-up roll RR2, and a plurality of printed coil substrates 100 are formed. The manufacturing method of the printed coil substrate 100 will be described in detail below. When showing a cross-sectional view used to explain the manufacturing method below, a cross-section cut along a cross-section corresponding to the line BB of the printed coil substrate 100 in FIG. 1 is shown.

[0031] Fig. 7 is a flowchart showing the order of steps in the manufacturing method of the printed coil board 100. Referring to Fig. 7, in a first step, a sheet 10A is prepared. Fig. 8 is a cross-sectional view of the sheet 10A prepared in the first step. A payout roll RR1 around which the sheet 10A is wound is prepared, and set in a payout section 501 of a roll-to-roll apparatus 500.

[0032] In the next second step, the first insulating layer 20A is formed on the sheet 10A. FIG. 9 is a cross-sectional view of the printed coil board 100 in the second step. Referring to FIG. 9, the first insulating layer 20A is formed on the upper surface of the sheet 10A. For example, the first insulating layer 20A is formed by laminating a sheet-like first insulating layer 20A on the upper surface of the sheet 10A. In this example, the material of the first insulating layer 20A is polyimide. Note that the first insulating layer 20A may be made of other resins such as epoxy. In addition, the first insulating layer 20A is made in a sheet shape, but may be made of a photosensitive resin precursor. In this case, the photosensitive resin precursor is applied to the upper surface of the sheet 10A, and the first insulating layer 20A is formed by exposing the photosensitive resin precursor to ultraviolet light.

[0033] In the next third step, a core layer and a support are formed. FIG. 10 is a cross-sectional view of the printed coil substrate 100 in the third step. FIG. 11 is a bottom view of the printed coil substrate 100 in the third step. In the third step, in order to form the core layer 10 and the wiring core layer 10Z, unnecessary portions of the sheet 10A are removed by etching. Specifically, a resist film is formed on the lower surface of the sheet 10A, and after exposure using a mask (not shown), the exposed portions of the resist film are removed. This exposes the unnecessary portions of the sheet 10A. Then, an etching solution is used to remove the portions of the sheet 10A on which the resist film is not formed. For example, a ferric chloride solution is used as the etching solution. When the sheet 10A is thick, the unnecessary portions of the sheet 10A may be removed by mechanical processing such as a drill.

[0034] By removing unnecessary portions of the sheet 10A, a core layer 10 having a circular ring shape in a plan view and a wiring core layer 10Z extending in one direction are formed. Through holes H1 and H2 are formed in the wiring core layer 10Z, which penetrate the wiring core layer 10Z in the vertical direction. The core layer 10 includes an upper surface 10a, a lower surface 10b, an outer side surface 10c, and an inner side surface 10d.

[0035] In the next fourth step, the first insulating layer 20B is formed on the lower surface. FIG. 12 is a cross-sectional view of the printed coil board 100 in the fourth step. In the fourth step, the first insulating layer 20B is formed on the lower surfaces of the first insulating layer 20A and the sheet 10A. For example, a sheet-like first insulating layer 20B is laminated on the lower surfaces of the first insulating layer 20A and the sheet 10A. In this example, the material of the first insulating layer 20B is polyimide, but it may be other resins such as epoxy. The first insulating layer 20 is formed by connecting the first insulating layer 20A and the first insulating layer 20B. As a result, the core layer 10 and the wiring core layer 10Z formed on the sheet 10A are covered with the first insulating layer 20. Specifically, the first insulating portion 20a is arranged on the upper surface 10a of the core layer 10, the second insulating portion 20b is arranged on the lower surface 10b of the core layer 10, and the third insulating portion 20c is arranged on the outer side surface 10c of the core layer 10.

[0036] The thickness of the first insulating layer 20B is constant. Therefore, as shown in FIG. 12, the thickness of the printed coil board 100 in the fourth step where the core layer 10 and the wiring core layer 10Z are arranged is larger than the thickness of the part where the core layer 10 and the wiring core layer 10Z are not arranged by the thickness of the sheet 10A. Therefore, a recess is formed in the through hole H1 of the first insulating layer 20 arranged in the space inside the core layer 10, and a recess is formed in the first insulating layer 20 arranged in the through hole H2 formed in the wiring core layer 10Z. The first insulating layer 20B may be formed from a photosensitive resin precursor. In this case, the first insulating layer 20B is formed by applying a photosensitive resin precursor to the lower surface of the first insulating layer 20A and the sheet 10A, and partially exposing the photosensitive resin precursor to ultraviolet light.

[0037] In the next fifth step, a plurality of outer holes and a center hole are formed. Fig. 13 is a cross-sectional view of the printed coil substrate 100 in the fifth step. Fig. 14 is a bottom view of the printed coil substrate 100 in the fifth step. In Fig. 14, the first insulating layer 20B is omitted. In the fifth step, a through hole h1, a through hole h2, and a plurality of through holes h3 are formed in the first insulating layer 20A.

[0038] As shown in FIG. 14, a through hole h1 is formed penetrating the first insulating layer 20 in the vertical direction, located inside the through hole H1 of the core layer 10 in plan view. The through hole h1 has a smaller diameter than the through hole H1. As a result, a fourth insulating portion 20d is formed on the inner side surface 10d of the core layer 10. Furthermore, a plurality of through holes h3 penetrating the first insulating layer 20 in the vertical direction is formed in the outer annular portion 20Z of the first insulating layer 20 located outside the core layer 10. The plurality of through holes h3 are arranged at equal intervals along a circle spaced outward from the core layer 10. Furthermore, a through hole h2 penetrating the first insulating layer 20 in the vertical direction is formed in the first insulating layer 20 located inside the through hole H2 of the wiring core layer 10Z in plan view. The through hole h1 is an example of a center hole, and the plurality of through holes h3 are an example of an outer hole. Each of the through holes h1, h2 and the plurality of through holes h3 is formed by laser processing or etching.

[0039] In the next sixth step, a plating resist is formed. FIG. 15 is a plan view of the printed coil substrate 100 in the sixth step. FIG. 16 is a bottom view of the printed coil substrate 100 in the sixth step. In the sixth step, a seed layer (not shown) is formed on the first insulating layer 20, and a plating resist PR is formed in regions other than the predetermined region R1 shown in FIG. 15 and FIG. 16. Therefore, the seed layer is exposed in the predetermined region R1. As shown in FIG. 15 and FIG. 16, a plating resist PR is formed between the multiple through holes h3. Therefore, the seed layer is not exposed between the multiple through holes h3.

[0040] In the next seventh step, electrolytic plating is performed. FIG. 17 is a cross-sectional view of the printed coil substrate 100 in the seventh step. FIG. 18 is a plan view of the printed coil substrate 100 in the seventh step. FIG. 19 is a bottom view of the printed coil substrate 100 in the seventh step. In the seventh step, a metal film of a single material is formed in the predetermined region R1 by electrolytic plating. As a result, the conductor layer 30, the wirings CL1 and CL2, and the external terminals IT and OT are simultaneously formed on the first insulating layer 20. The conductor layer 30 is formed simultaneously and therefore has no seams. The conductor layer 30 has a spiral shape surrounding the core layer 10 on the first insulating layer 20 formed around the core layer 10. The conductor layer 30 includes a first conductor portion 31 located on the upper surface, a second conductor portion 32 located on the lower surface, a third conductor portion 33 located outward from the core layer 10, and a fourth conductor portion 34 located inward from the core layer 10. Specifically, as shown in FIG. 18, among the plurality of first conductor parts 31, a starting end 30A corresponding to an end of the conductor layer 30 extends from the outside of the core layer 10 toward the center of the through hole h1. The width of the first conductor part 31 gradually decreases in a direction from the outside to the inside. The width of the first conductor part 31 at a portion overlapping with one through hole h3 may be larger than the width of the one through hole h3. The first conductor part 31 is connected to the fourth conductor part 34. As shown in FIG. 17, the fourth conductor part 34 extends downward along the first insulating layer 20 in the through hole h1. The fourth conductor part 34 is connected to the second conductor part 32. As shown in FIG. 19, the second conductor part 32 extends toward the one through hole h3. The width of the second conductor part 32 at a portion overlapping with one through hole h3 may be larger than the width of the one through hole h3. The width of the second conductor part 32 gradually increases in a direction from the inside to the outside. Here, one through hole h3 is a through hole h3 among the multiple through holes h3 that is adjacent to the starting end 30A on the upper surface. The second conductor portion 32 is connected to the third conductor portion 33. As shown in Fig. 17, the third conductor portion 33 extends upward along the first insulating layer 20 within the through hole h3.

[0041] The conductor layer 30 is connected in the order of the first conductor portion 31, the fourth conductor portion 34, the second conductor portion 32, and the third conductor portion 33, so that the conductor layer 30 has a spiral shape that winds around the core layer 10 on the first insulating layer 20 through the multiple through holes h3 and h1. As shown in Fig. 19, a terminal portion 30B of the multiple second conductor portions 32 that corresponds to the end of the conductor layer 30 extends from the through hole h1 toward the outside of the core layer 10 without being connected to the third conductor portion 33.

[0042] In addition, an external terminal OT is formed on the upper surface of the first insulating layer 20 formed around the wiring core layer 10Z at a position separated from the core layer 10, and an external terminal IT is formed at a position between the core layer 10 and the external terminal OT. The start end 30A of the first conductor portion 31 located on the upper surface and the external terminal IT located on the upper surface of the wiring core layer 10Z are connected by the wiring CL1 located on the upper surface. The end end 30B of the second conductor portion 32 located on the lower surface and the external terminal OT located on the upper surface of the wiring core layer 10Z are connected through the through hole h2 by the wiring CL2 located on the lower surface. The conductor layer 30, the wiring CL1, CL2, and the external terminals IT, OT may be formed by a semi-additive method, an additive method, or other methods such as a subtractive method. When the conductor layer 30, the wiring CL1, CL2, and the external terminals IT, OT are formed, the plating resist PR is removed, and the seed layer on the first insulating layer 20 is removed by etching except for a predetermined region.

[0043] In the next eighth step, a second insulating layer is formed. FIG. 20 is a cross-sectional view of the printed coil board 100 in the eighth step. In the eighth step, a second insulating layer 40 is formed to cover the first insulating layer 20 and the conductor layer 30 except for the external terminals IT and OT. Specifically, the second insulating layer 40A is formed on the upper surface of the sheet 10A, and the second insulating layer 40B is formed on the lower surface of the sheet 10A. The procedure for forming the second insulating layer 40A is the same as the procedure for forming the first insulating layer 20A, and the procedure for forming the second insulating layer 40B is the same as the procedure for forming the first insulating layer 20B. The photosensitive resin precursor applied to the upper surfaces of the external terminals IT and OT is not exposed to light, so that the external terminals IT and OT are exposed from the second insulating layer 40A. The second insulating layer 40A and the second insulating layer 40B are connected to each other to form the second insulating layer 40.

[0044] In the final ninth step, the first insulating layer is cut, and the printed coil substrate 100 is separated from the sheet 10A. FIG. 21 is a plan view of the printed coil substrate 100 in the ninth step. In FIG. 21, the second insulating layer 40 is omitted. The second insulating layer 40 (not shown) and the first insulating layer 20 are cut along the cutting line LL shown in FIG. 21. The cutting line LL includes a line LL1 that connects two adjacent ones of the plurality of through holes h3 in a region other than the region in which the wirings CL1 and CL2 are arranged. The cutting line LL also includes a line LL2 that extends parallel to the wirings CL1 and CL2 from both ends of the line LL1, and a line LL3 that is connected to the line LL2 and surrounds the wiring core layer 10Z. In the ninth step, the first insulating layer 20A is cut along the cutting line LL by, for example, laser processing (see FIG. 20). This completes the printed coil substrate 100 shown in FIG. 1. The first insulating layer 20 is cut along the cutting line LL of the line LL1, so that the cut surface becomes the outer peripheral side surface of the outer annular portion 20Z. Also, the first insulating layer 20 is cut along the cutting line LL of the line LL1, so that the inner peripheral surface of each of the plurality of through holes h3 becomes an outer peripheral recess recessed inward from the outer peripheral side surface of the outer annular portion 20Z.

[0045] (3) Effects of the embodiment According to this printed coil board 100, the conductor layer 30 has a spiral shape and functions as a coil. Since the conductor layer 30 has no seams, the change in resistance of the conductor layer 30 can be reduced. In addition, since the width of the conductor layer 30 gradually increases in the direction from the inside to the outside of the core layer, the width of the conductor layer 30 at the inner side surface 10d of the core layer is narrower than the width of the conductor layer 30 at the outer side surface 10c of the core layer. This allows the number of turns of the conductor layer 30 to be increased. This allows the inductance of the printed coil board 100 to be increased and the electrical resistance of the conductor layer 30 to be reduced. As a result, it is possible to provide a printed coil board 100 including a coil with improved performance while suppressing an increase in size.

[0046] Moreover, since the third conductor portion 33 is disposed in the outer peripheral recess 22, adjacent third conductor portions 33 are separated by the outer side surface 10c. In this case, the occurrence of a short circuit in the spiral conductor layer 30 is suppressed, so that the reliability of the printed coil board 100 can be improved.

[0047] According to the manufacturing method of the above embodiment, the conductor layer 30 passes through the through hole h1 and each of the multiple through holes h3, and therefore the conductor layer 30 passing through each of the multiple through holes h3 is separated by the region between the multiple through holes h3. Therefore, the spiral conductor layer 30 can be easily formed.

[0048] In addition, since the conductor layer 30 is simultaneously formed by metal plating, the process of forming the conductor layer 30 can be combined into one, and it is possible to form the conductor layer 30 as a single, seamless body. As a result, it is possible to suppress the occurrence of interfacial peeling, and it is possible to improve the connection reliability of the conductor layer 30. In addition, the manufacturing time of the printed coil board 100 can be shortened.

[0049] (4) Variations in manufacturing method In the manufacturing method of the above embodiment, an example is described in which the conductor layer 30 is wound through the through holes H1, h1 and the plurality of through holes h3, but the present invention is not limited thereto. Figs. 22 and 23 are diagrams for explaining a manufacturing method of a printed coil substrate in a modified example. Figs. 22 and 23 show plan views. The manufacturing method of the modified example differs from the manufacturing method described above in the following respects. In the manufacturing method of the modified example, the through hole h1 is not formed in the through hole H1 in the fifth step, and the plurality of through holes h4 are formed along the inner side surface 10d of the core layer 10 as shown in Fig. 22. As a result, in the conductor layer 30 formed in the seventh step, the first conductor portion 31 located on the upper surface and the second conductor portion 32 located on the lower surface are connected through the through hole h4 as shown in Fig. 23. Thereafter, in the eighth step, the first insulating layer 20 is cut along a cutting line connecting two adjacent ones of the plurality of through holes h4. In this case, the plurality of fourth conductor portions 34 are separated by the region between the plurality of through holes h4. Since contact between adjacent fourth conductors 34 among the plurality of fourth conductors 34 can be prevented, it is possible to provide a printed coil board 100 that can further suppress the occurrence of short circuits.

[0050] (5) Examples and Comparative Examples A Q value was calculated to evaluate the performance of the printed coil board 100 according to the present embodiment. In the embodiment, the printed coil board 100 of FIG. 1 was used. FIG. 24 is a perspective view of a printed coil board used in a comparative example. The printed coil board 100 of FIG. 1 and the printed coil board 600 of FIG. 24 differ in the following respects. The conductor layer 30 of the printed coil board 600 has a uniform width. The widths of the multiple first conductor parts 31 on the upper surface 10a of the core layer 10 are uniform, and the intervals between the multiple first conductor parts 31 gradually increase from the inside to the outside. The widths of the multiple second conductor parts 32 on the lower surface 10b of the core layer 10 are uniform, and the intervals between the multiple second conductor parts 32 gradually increase from the inside to the outside.

[0051] Here, the printed coil board 600 in FIG. 24 is called type A, and the printed coil board 100 in FIG. 1 is called type B. A quality test was conducted on the type A printed coil board and the type B printed coil board. In the quality test, a type A printed coil board and a type B printed coil board in which the number of turns of the conductor layer 30 around the core layer 10 is 60, and a type A printed coil board and a type B printed coil board in which the number of turns of the conductor layer 30 around the core layer 10 is 90, were used. In the quality test, a voltage was applied from an external current supply device to the external terminals IT and OT of each of the four printed coil boards. At that time, the frequency of the applied voltage was changed to measure the change in the resistance value R (Ω) and the change in the inductance value L (μH) for each of the four printed coil boards.

[0052] FIG. 25 is a diagram showing the change in resistance value R of the type A printed coil board and the type B printed coil board. Here, the change in resistance value R when the frequency of the current is changed when a current is supplied to the type A printed coil board and the type B printed coil board is shown. As shown in FIG. 25, it was found that the resistance value R of the type A printed coil board in which the number of turns of the conductor layer 30 around the core layer 10 is 60 is higher at all frequencies than the resistance value of the type B printed coil board in which the number of turns of the conductor layer 30 around the core layer 10 is 60. Similarly, it was found that the resistance value R of the type A printed coil board in which the number of turns of the conductor layer 30 around the core layer 10 is 90 is higher at all frequencies than the resistance value R of the type B printed coil board in which the number of turns of the conductor layer 30 around the core layer 10 is 90.

[0053] FIG. 26 is a diagram showing the change in the value of inductance L of the type A printed coil board and the type B printed coil board. Here, the change in the value of inductance L when the frequency of the current is changed when a current is supplied to the type A printed coil board and the type B printed coil board is shown. It was found that the value of inductance L of the type A printed coil board in which the number of turns of the conductor layer 30 around the core layer 10 is 60 is higher at all frequencies than the value of inductance L of the type B printed coil board in which the number of turns of the conductor layer 30 around the core layer 10 is 60. Similarly, it was found that the value of inductance L of the type A printed coil board in which the number of turns of the conductor layer 30 around the core layer 10 is 90 is higher at all frequencies than the value of inductance L of the type B printed coil board in which the number of turns of the conductor layer 30 around the core layer 10 is 90.

[0054] The Q value is an abbreviation of the Quality Factor, and is a parameter that indicates the quality of a coil. The Q value is expressed by the following formula (1), where ω is the angular frequency.

[0055]

number

[0056] Fig. 27 is a diagram showing changes in the Q value of type A printed coil board and type B printed coil board. The diagram shows changes in the Q value when the frequency of a current is changed when a current is supplied to type A printed coil board and type B printed coil board. The changes in the Q value in Fig. 27 are calculated from the changes in the resistance value R for each frequency and the changes in the value of inductance L for each frequency, and from the above formula (1).

[0057] 27, it was found that the Q value of the type B printed coil board in which the number of turns of the conductor layer 30 around the core layer 10 is 60 is higher than the Q value of the type A printed coil board in which the number of turns of the conductor layer 30 around the core layer 10 is 60. Similarly, it was found that the Q value of the type B printed coil board in which the number of turns of the conductor layer 30 around the core layer 10 is 90 is higher than the Q value of the type A printed coil board in which the number of turns of the conductor layer 30 around the core layer 10 is 90. As a result of these, it was confirmed that the Q value of a coil in which the width of the wiring increases from the inside to the outside is improved compared to the Q value of a coil in which the width of the wiring is the same.

[0058] (6) Other embodiments In the above embodiment, the annular shape of the core layer 10 is a perfect annular shape with equal radii in two directions perpendicular to each other on a plane, but the embodiment is not limited thereto. The annular shape of the core layer 10 may be an elliptical annular shape with different radii in two directions perpendicular to each other on a plane. Alternatively, the annular shape of the core layer 10 may be an elliptical annular shape. Details of the elliptical annular core layer 10 will be described later with reference to FIG. 28.

[0059] In the core layer 10 having an elliptical or oval ring shape, even if the volume of the core layer 10 is equal to that of a core layer 10 having a perfect ring shape, the magnetic path length is large. That is, the magnetic resistance is large. Therefore, even if the current flowing through the conductor layer 30 changes, the decrease in magnetic permeability is gradual. As a result, the decrease in inductance due to the change in current is suppressed.

[0060] FIG. 28 is a plan view of a printed coil substrate according to another embodiment. In FIG. 28, the wiring core layer 10Z, the second insulating layer 40, and the external terminals IT, OT, etc. are omitted. As shown in FIG. 28, in this embodiment, the core layer 10 has an oval ring shape. Specifically, the core layer 10 includes curved portions 11, 12 and straight portions 13, 14. The curved portions 11, 12 have curved shapes. The curved portion 11 has one semicircular ring shape obtained by dividing one perfect ring shape in half, and the curved portion 12 has the other semicircular ring shape. The curved portion 11 may have a semi-elliptical ring shape obtained by dividing one elliptical ring shape in half, and the curved portion 12 may have the other semi-elliptical ring shape. Each of the straight portions 13, 14 has a rod shape extending in one direction. The straight portion 13 connects one end of the curved portion 11 to one end of the curved portion 12. Straight portion 14 connects the other end of curved portion 11 and the other end of curved portion 12 .

[0061] The upper surface 10a, the lower surface 10b, the outer side surface 10c, and the inner side surface 10d of the core layer 10 are covered with a first insulating layer 20. The conductor layer 30 has a seamless spiral shape and is disposed on the first insulating layer 20 so as to surround the core layer 10. In this configuration, the width of the portion of the conductor layer 30 surrounding the straight portions 13, 14 of the core layer 10 is uniform. That is, the width of the multiple first conductor portions 31 on the upper surfaces 10a of the straight portions 13, 14 is uniform, and the width of the multiple second conductor portions 32 on the lower surfaces 10b of the straight portions 13, 14 is uniform.

[0062] On the other hand, the width of the portion of the conductor layer 30 surrounding the curved portions 11 and 12 of the core layer 10 gradually increases from the inner side surface 10d to the outer side surface 10c of the core layer 10. That is, the width of each of the multiple first conductor portions 31 on the upper surface 10a of the curved portions 11 and 12 gradually increases from the inner side surface 10d to the outer side surface 10c of the core layer 10. Also, the width of each of the multiple second conductor portions 32 on the lower surface 10b of the curved portions 11 and 12 gradually increases from the inner side surface 10d to the outer side surface 10c of the core layer 10. Therefore, in this example, the width of at least a part of the portion of the conductor layer 30 gradually increases in the direction from the inside to the outside of the core layer 10.

[0063] As described above, the printed coil board 100 in Fig. 1 is called type B. Also, the printed coil board 100 in Fig. 28 is called type C. A simulation was performed to evaluate the quality of the type B printed coil board and the type C printed coil board. In the simulation, a type B printed coil board and a type C printed coil board having the same volume of the core layer 10 and the same number of turns of the conductor layer 30 relative to the core layer 10 were used.

[0064] In the simulation, an AC voltage with a frequency of 1 MHz was applied from an external current supply device to the external terminals IT and OT of each of the two printed coil boards. At that time, the current flowing through the conductor layer 30 was changed from 0 A to 2 A to confirm the change in inductance value L (μH) for each printed coil board. Here, similar to the measurement of the DC superposition characteristics of inductance, the current value at which the inductance decreased by 30% from the value at which inductance occurred near a current value slightly larger than 0 A was defined as the rated current.

[0065] Fig. 29 is a diagram showing simulation results in another embodiment. As shown in Fig. 29, the rated current for the type B printed coil board was 0.81 A. On the other hand, the rated current for the type C printed coil board was 1.53 A. From these results, it was confirmed that the rated current was increased by making the core layer 10 into an elliptical ring shape. In other words, it was confirmed that the range in which the inductance is maintained approximately constant was increased by making the core layer 10 into an elliptical ring shape. Similar results were obtained even when the core layer 10 had an elliptical ring shape.

[0066] (7) Summary of implementation form (Item 1) A printed coil board according to one aspect of the present invention comprises: an annular core layer having a first main surface and a second main surface facing opposite directions; A first insulating layer covering the core layer; a conductor layer having a seamless spiral shape and surrounding the core layer on the first insulating layer; The width of at least a portion of the conductor layer on at least one of the first main surface and the second main surface gradually increases in a direction from the inside to the outside of the core layer.

[0067] According to this printed coil board, the conductor layer has a spiral shape and therefore functions as a coil. The conductor layer has no seams, so that the change in resistance of the conductor layer can be reduced. Furthermore, the width of at least a portion of the conductor layer gradually increases in the direction from the inside to the outside of the core layer, so that the width of the conductor layer on the inside side surface of the core layer is narrower than the width of the conductor layer on the outside side surface of the core layer. This allows the number of turns of the conductor layer to be increased. This makes it possible to increase the inductance of the printed coil board and reduce the electrical resistance of the conductor layer. As a result, it is possible to provide a printed coil board including a coil with improved performance while suppressing an increase in size.

[0068] (Item 2) In the printed coil board according to item 1, The conductor layer is A first conductor portion located on the first main surface side; A second conductor portion located on the second main surface side; a third conductor portion located outside the core layer and connecting the first conductor portion and the second conductor portion, the first insulating layer has an outer peripheral recess recessed inward on an outer peripheral side surface of an outer annular portion located outward of the core layer, The third conductor portion may be disposed in the outer circumferential recess.

[0069] According to this printed coil board, since the third conductor portion is disposed in the outer peripheral recess, adjacent third conductor portions are separated by the outer side surface. In this case, occurrence of a short circuit due to contact between the spiral conductor layers is suppressed, so that it is possible to improve the reliability of the printed coil board.

[0070] (Item 3) In the printed coil board according to item 1 or 2, The core layer may have a thickness of 10 μm or more and 500 μm or less.

[0071] According to this printed coil board, the thickness of the core layer is prevented from increasing, so that the printed coil board can be made thinner.

[0072] (Item 4) In the printed coil board according to any one of items 1 to 3, The conductor layer may have a thickness of 2 μm or more and 500 μm or less.

[0073] According to this printed coil board, the thickness of the conductor layer is prevented from increasing, so that the printed coil board can be made thinner.

[0074] (Item 5) In the printed coil board according to any one of items 1 to 4, a second insulating layer covering the core layer, the first insulating layer, and the conductor layer; The maximum thickness of the printed coil board may be 20 μm or more and 1.0 mm or less.

[0075] According to this printed coil board, it is possible to provide a printed coil board that is thinned to the order of microns.

[0076] (Item 6) A method for manufacturing a printed coil substrate according to another aspect of the present invention includes the steps of: providing a magnetic layer having first and second opposing major surfaces; forming an insulating layer on the first major surface of the magnetic layer; forming a ring-shaped core layer by removing a predetermined region of the magnetic layer; the core layer has the first main surface, the second main surface, an inner side surface connecting the first main surface and the second main surface and positioned inward, and an outer side surface connecting the first main surface and the second main surface and positioned outward, forming another insulating layer on the first insulating layer, the second main surface, the inner side surface and the outer side surface of the core layer; forming a plurality of outer holes penetrating the first insulating layer and the second insulating layer at a plurality of positions aligned along a circle spaced outward from the core layer, and a central hole penetrating the first insulating layer and the second insulating layer at a position spaced inward from the core layer; forming a conductor layer on the first insulating layer and the second insulating layer, the conductor layer passing through the central hole and each of the outer holes and spirally surrounding the core layer; the conductor layer includes a first conductor portion located on the first main surface of the core layer and a second conductor portion located on the second main surface of the core layer, and a width of at least a part of at least one of the first conductor portion and the second conductor portion gradually increases in a direction from the inside to the outside of the core layer; and cutting the one insulating layer and the other insulating layer along a cutting line connecting two adjacent ones of the plurality of outer holes.

[0077] In the printed coil board manufactured by this manufacturing method, the conductor layer has a spiral shape and functions as a coil. Since the width of at least a part of the conductor layer gradually increases in a direction from the inside to the outside of the core layer, the width of the conductor layer on the inner side surface of the core layer is narrower than the width of the conductor layer on the outer side surface of the core layer. Therefore, the number of turns of the conductor layer can be increased. Therefore, the inductance of the printed coil board can be increased and the electrical resistance of the conductor layer can be reduced. In addition, since the conductor layer passes through the center hole and each of the multiple through holes, the conductor layer passing through each of the multiple through holes is separated by the region between the multiple through holes. Therefore, a spiral-shaped conductor layer can be easily formed. As a result, a manufacturing method can be provided that can easily manufacture a printed coil board including a coil with improved performance while suppressing an increase in size.

[0078] (Item 7) In the method for producing a printed coil board according to item 6, the step of forming the conductor layer may include simultaneously forming the conductor layer by electrolytic plating.

[0079] According to the manufacturing method described in item 7, the conductor layers are simultaneously formed by electrolytic plating, so that the process of forming the conductor layers can be combined into one and it is possible to form a seamless conductor layer as an integral body. As a result, it is possible to shorten the manufacturing time and manufacture a printed coil board with improved connection reliability of the conductor layers. [Explanation of symbols]

[0080] 10...core layer, 10A...sheet, 10Z...wiring core layer, 10a...upper surface, 10b...lower surface, 10c...outer side surface, 10d...inner side surface, 11, 12...curved portion, 13, 14...straight portion, 20, 20A, 20B...first insulating layer, 20Y...inner annular portion, 20Z...outer annular portion, 20a to 20d...first insulating portion to fourth insulating portion, 21a...recess side surface, 22...peripheral recess, 22a...outer surface, 30...conductor layer, 30A...starting end portion, 30B...terminating end portion, 31 to 34...first conductor portion to fourth conductor portion Body portion, 34a... inner side surface, 40, 40A, 40B... second insulating layer, 90... metal support, 100... printed coil board, 500... roll device, 501... unwinding section, 502... winding section, 600... printed coil board, CL1, CL2... wiring, H1, H2... through hole, IT... external terminal, L... inductance, LL... cutting line, OT... external terminal, PR... plating resist, R1... specified area, RR1... unwinding roll, RR2... winding roll, h1 to h4... through hole

Claims

1. an annular core layer having a first major surface and a second major surface facing opposite directions; a first insulating layer covering the core layer; a conductor layer having a seamless spiral shape and surrounding the core layer on the first insulating layer; A printed coil board, wherein a width of at least a portion of the conductor layer on at least one of the first main surface and the second main surface gradually increases in a direction from the inside to the outside of the core layer.

2. The conductor layer is A first conductor portion located on the first main surface side; A second conductor portion located on the second main surface side; a third conductor portion located outside the core layer and connecting the first conductor portion and the second conductor portion, the first insulating layer has an outer peripheral recess recessed inward on an outer peripheral side surface of an outer annular portion located outward of the core layer, The printed coil board according to claim 1 , wherein the third conductor portion is disposed in the outer circumferential recess.

3. 3. The printed coil board according to claim 1, wherein the core layer has a thickness of 10 [mu]m or more and 500 [mu]m or less.

4. 3. The printed coil board according to claim 1, wherein the conductor layer has a thickness of 2 [mu]m or more and 500 [mu]m or less.

5. a second insulating layer covering the core layer, the first insulating layer, and the conductor layer; 3. The printed coil board according to claim 1, wherein the maximum thickness of said printed coil board is 20 [mu]m or more and 1.0 mm or less.

6. providing a magnetic layer having first and second opposing major surfaces; forming an insulating layer on the first major surface of the magnetic layer; forming a ring-shaped core layer by removing a predetermined region of the magnetic layer; the core layer has the first main surface, the second main surface, an inner side surface connecting the first main surface and the second main surface and positioned inward, and an outer side surface connecting the first main surface and the second main surface and positioned outward, forming another insulating layer on the first insulating layer, the second main surface, the inner side surface and the outer side surface of the core layer; forming a plurality of outer holes penetrating the first insulating layer and the second insulating layer at a plurality of positions aligned along a circle spaced outward from the core layer, and a central hole penetrating the first insulating layer and the second insulating layer at a position spaced inward from the core layer; forming a conductor layer on the first insulating layer and the second insulating layer, the conductor layer passing through the central hole and each of the outer holes and spirally surrounding the core layer; the conductor layer includes a first conductor portion located on the first main surface of the core layer and a second conductor portion located on the second main surface of the core layer, and a width of at least a part of at least one of the first conductor portion and the second conductor portion gradually increases in a direction from the inside to the outside of the core layer; cutting the one insulating layer and the other insulating layer along a cutting line connecting two adjacent ones of the plurality of outer holes.

7. 7. The method for producing a printed coil board according to claim 6, wherein the step of forming the conductor layer includes simultaneously forming the conductor layer by electrolytic plating.

Images