An inductor includes a stacked body with a plurality of structural bodies that are stacked. Each of the plurality of structural bodies includes a wiring and an insulation layer formed on the wiring. The wirings of the plurality of structural bodies are connected in series to form a helical coil. The inductor further includes a through hole, which extends through the stacked body in a thickness direction of the stacked body, and a plurality of discrete insulation films, which are spaced apart from each other and cover surfaces of the wires of the plurality of structural bodies exposed from a surface of the stacked body.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2015-101891, filed on May 19, 2015, the entire contents of which are incorporated herein by reference.

FIELD

This disclosure relates to an inductor and a method for manufacturing an inductor.

BACKGROUND

Electronic devices such as computer games and cellular phones are becoming smaller and smaller. As a result, elements such as inductors mounted in such an electronic device also need to be smaller. One example of a known inductor mounted in such an electronic device uses a winding coil. For example, an inductor that uses a winding coil may be mounted in a power supply circuit of an electronic device (see Japanese Laid-Open Patent Publication No. 2003-168610).

SUMMARY

The limit to miniaturization of the inductor that uses a winding coil is considered to be approximately 1.6 mm×1.6 mm in planar shape. This is because there is a limit to the thickness of the winding. Further miniaturized of the inductor would decrease the proportion of the volume of the winding wiring relative to the total area of the inductor reduces, and a large inductance would not be obtained. Thus, the development of an inductor that can easily be miniaturized is desired.

One aspect of this disclosure is an inductor including a stacked body, a first through hole, and a plurality of first discrete insulation films. The stacked body includes a plurality of structural bodies that are stacked. Each of the plurality of structural bodies includes a wiring and an insulation layer formed on the wiring. The wirings of the plurality of the plurality of structural bodies that are adjacent in a stacking direction of the stacked body are connected in series to form a helical coil. The first through hole extends through the stacked body in the stacking direction. The plurality of first discrete insulation films are spaced apart from each other and cover surfaces of the wirings of the plurality of structural bodies that are exposed from a surface of the stacked body.

DESCRIPTION OF THE EMBODIMENTS

Embodiments will hereinafter be described with reference to the accompanying drawings. In the drawings, elements are illustrated for simplicity and clarity and have not necessarily been drawn to scale. To facilitate understanding, hatching lines may not be illustrated or be replaced by shading in the cross-sectional drawings.

First Embodiment

A first embodiment will now be described with reference toFIGS. 1 to 31.

The structure of a coil substrate10will first be described.

As illustrated inFIG. 1, a coil substrate10is formed to have a substantially rectangular shape in a plan view, for example. The coil substrate10includes a block11, and two outer frames13projecting toward an outer side from the block11. The block11is, for example, formed to have a substantially rectangular shape in a plan view. The block11includes a plurality of individual regions A1arranged in a matrix form (here, 2×6). The block11is ultimately cut along broken lines (each individual region A1) and singulated into individual unit coil substrates20(hereinafter simply referred to as the coil substrates20). In other words, the block11includes the plurality of individual regions A1each used as the coil substrate20.

The plurality of individual regions A1may be laid out at a predetermined interval as illustrated inFIG. 1or may be laid out in contact with each other. The block11includes twelve individual regions A1in the example illustrated inFIG. 1. However, the number of individual regions A1is not particularly limited.

The block11includes a coupling portion12that couples the plurality of coil substrates20. In other words, the coupling portion12supports the plurality of coil substrates20so as to surround the coil substrates20.

The outer frames13are, for example, formed at the two end regions of the coil substrate10. For example, the outer frames13project toward the outer side from the short sides of the block11. Each outer frame13includes a plurality of sprocket holes13X. The plurality of sprocket holes13X are, for example, continuously arranged at substantially constant intervals in a short-side direction (vertical direction as viewed inFIG. 1) of the coil substrate10. Each sprocket hole13X has a substantially rectangular shape in a plan view, for example. The sprocket holes13X are through holes used to convey the coil substrate10. When the coil substrate10is attached to a manufacturing device, the through holes are engaged with pins of a sprocket driven by a motor or the like to convey the coil substrate10at the pitch of the sprocket holes13X. Thus, the interval of the adjacent sprocket holes13X is set in correspondence with the manufacturing device to which the coil substrate10is attached. A portion (i.e., coupling portion12and outer frames13) other than the individual regions A1of the coil substrate10is discarded after singulating the coil substrate10into the coil substrates20.

The structure of each coil substrate20will now be described according toFIGS. 2 to 7.

As illustrated inFIG. 2, the coil substrate20of each individual region A1is formed to have a substantially rectangular shape in a plan view, for example. The planar shape of the coil substrate20is, for example, a rectangle having chamfered corners. The coil substrate20includes projections21,22projecting toward the outer side (upper side and lower side inFIG. 2) from the short sides of the rectangle. The planar shape of the coil substrate20is, however, not limited to the shape illustrated inFIG. 2, and may have any shape. Furthermore, the planar shape of the coil substrate20may have any size. For example, the planar shape of the coil substrate20may have a size so that the planar shape of an inductor90is a substantially rectangular shape of approximately 1.6 mm×0.8 mm when the inductor90illustrated inFIG. 8Bis manufactured using the coil substrate20. The thickness of the coil substrate20is, for example, approximately 0.5 mm.

A through hole20X is formed at substantially a central part in a plan view of the coil substrate20. The through hole20X extends through the coil substrate20in a thickness direction. The planar shape of the through hole20X may have any shape and any size. For example, the planar shape of the through hole20X may be a substantially elliptical shape or a substantially oval shape.

An opening20Y that defines the coil substrate20is formed between the coil substrate20and the coupling portion12. The opening20Y extends through the coil substrate10in the thickness direction.

As illustrated inFIGS. 3 and 4, the coil substrate20mainly includes a stacked body23and an insulation film25, which covers the surface of the stacked body23. The stacked body23includes a substrate30, a structural body41stacked on a lower surface30A of the substrate30, and structural bodies42to47sequentially stacked on an upper surface30B of the substrate30.

The planar shape of the stacked body23is substantially similar to the planar shape of the coil substrate20. For example, the planar shape of the stacked body23is one size smaller than the planar shape of the coil substrate20due to the insulation film25. A through hole23X that extends through the stacked body23in the thickness direction is formed at substantially the central part in a plan view of the stacked body23. The planar shape of the through hole23X may be, for example, a substantially elliptical shape or a substantially oval shape like the planar shape of the through hole20X.

In the stacked body23, the structural body42is stacked on the upper surface30B of the substrate30by way of an adhesive layer71. The structural body43is stacked on the structural body42by way of an adhesive layer72. The structural body44is stacked on the structural body43by way of an adhesive layer73. The structural body45is stacked on the structural body44by way of an adhesive layer74. The structural body46is stacked on the structural body45by way of an adhesive layer75. The structural body47is stacked on the structural body46by way of an adhesive layer76.

A heat resistant adhesive formed from an insulative resin, for example, may be used as the adhesive layers71to76. For example, an epoxy-based adhesive is used for the adhesive layers71to76. The thicknesses of the adhesive layers71to76may be, for example, approximately 12 to 35 μm.

As illustrated inFIG. 4, the structural body41includes an insulation layer51, a wiring61, a connecting portion61A, and a metal layer61D. The structural body42includes an insulation layer52, a wiring62, and a metal layer62D. The structural body43includes an insulation layer53, a wiring63, and a metal layer63D. The structural body44includes an insulation layer54, a wiring64, and a metal layer64D. The structural body45includes an insulation layer55, a wiring65, and a metal layer65D. The structural body46includes an insulation layer56, a wiring66, and a metal layer66D. The structural body47includes an insulation layer57, a wiring67, a connecting portion67A, and a metal layer67D.

An insulative resin in which an epoxy-based resin is the main component may be used as the material of the insulation layers51to57. Alternatively, an insulative resin in which a thermosetting resin is the main component may be used as the material of the insulation layers51to57. Furthermore, the insulation layers51to57may contain a filler such as silica, alumina, or the like. The thermal expansion coefficient of the insulation layers51to57is, for example, 50 to 120 ppm/° C. The thicknesses of the insulation layers51to57may be, for example, approximately 12 to 20 μm.

The wiring61is located in the lowermost wiring layer. A metal material having a higher adhesiveness to the insulation film25than the substrate30, for example, is preferable for the material of the wiring61of the lowermost layer, the connecting portion61A, and the metal layer61D. For example, copper (Cu) or copper alloy may be used as the material of the wiring61, the connecting portion61A, and the metal layer61D. In the same manner, copper and copper alloy may be used, for example, as the material of the wirings62to67, the connecting portion67A, and the metal layers62D to67D. The thicknesses of the wirings61to67, the connecting portions61A,67A, and the metal layers61D to67D may be, for example, approximately 12 to 35 μm.

A sheet-like insulating substrate, for example, may be used as the substrate30. An insulative resin, for example, may be used as the material of the substrate30. The insulative resin is preferably adjusted so that the thermal expansion coefficient of the substrate30becomes lower than the thermal expansion coefficient of the insulation layers51to57. For example, the thermal expansion coefficient of the substrate30is set to approximately 10 to 25 ppm/° C. A material having superior heat resistance, for example, is preferable for the material for the substrate30. A material having a higher elastic modulus than the insulation layers51to57is preferable for the material of the substrate30. A resin film such as polyimide (PI) film, polyethylene naphthalate (PEN) film, and the like, for example, may be used as the substrate30. For example, the polyimide film having a low thermal expansion coefficient may be used as the substrate30. The thickness of the substrate30is, for example, set to be thicker than the insulation layers51to57. For example, the thickness of the substrate30may be approximately 12 to 50 μm. Such a substrate30has a higher rigidity than the insulation layers51to57.

As illustrated inFIGS. 4 and 5, the substrate30includes a through hole30X that extends through the substrate30in the thickness direction. The planar shape of the through hole30X may have any shape and any size. For example, the planar shape of the through hole30X may be a circular shape having a diameter of approximately 200 to 300 μm.

The structure of the structural body41will now be described.

The insulation layer51is stacked on the lower surface30A of the substrate30. The insulation layer51includes a through hole51X that extends through the insulation layer51in the thickness direction. The through hole51X communicates with the communication hole30X of the substrate30. In other words, the through hole51X is formed at a position overlapping the through hole30X in a plan view. The planar shape of the through hole51X may have any shape and any size. For example, the planar shape of the through hole51X may be a circular shape having a diameter of approximately 200 to 300 μm like the through hole30X.

A via wiring V1is formed partially in the through holes30X and51X, which are in communication. In the present example, the through hole51X and a portion of the through hole30X are filled with the via wiring V1. Furthermore, in the present example, the via wiring V1extends from the upper surface of the wiring61to an intermediate position of the through hole30X in the thickness direction of the substrate30. Thus, the upper inner side surface of the through hole30X is exposed from the via wiring V1. The via wiring V1is electrically connected to the wiring61. The planar shape of the via wiring V1may have any shape and any size. For example, the planar shape of the via wiring V1may be a circular shape having a diameter of approximately 200 to 300 μm like the through holes30X,51X.

The wiring61, the connecting portion61A, and the metal layer61D are stacked on the lower surface of the insulation layer51. The wiring61, the connecting portion61A, and the metal layer61D are located on the lowermost layer of the stacked body23. The width of the wiring61is, for example, approximately 100 to 200 μm. The wiring61is a portion of a helical coil formed in the coil substrate20and serves as a first-layer wiring (about one winding) of the coil. In the description hereafter, the direction in which the helical winding of the coil extends is referred to as the longitudinal direction and the direction orthogonal to the longitudinal direction in a plan view is referred to as the widthwise direction of each wiring.

As illustrated inFIG. 5, the planar shape of the wiring61is elliptical. A groove61Y that extends through the wiring61in the thickness direction is formed at a certain location in the wiring61. That is, the wiring61is cut in the widthwise direction by the groove61Y and formed to have a non-ring-like shape.

The connecting portion61A is formed at one end of the wiring61. The connecting portion61A is formed at a position corresponding to the projection21(refer toFIG. 2) of the coil substrate20. The connecting portion61A is formed integrally with the wiring61. In other words, the connecting portion61A is a portion of the wiring61. As illustrated inFIG. 4, the connecting portion61A is electrically connected to the metal layer81formed in the coupling portion12(refer toFIG. 3). The metal layer81is, for example, a power supply line for supplying power during plating. The connecting portion61A is exposed from the insulation film25at the side surface20A (refer toFIG. 8A) of the coil substrate20subsequent to singulation. The connecting portion61A is connected to an electrode92of the inductor90(refer toFIG. 8B).

The metal layer61D is spaced apart from the wiring61. In other words, a groove61Z is formed between the metal layer61D and the wiring61. Therefore, the metal layer61D is electrically insulated from the wiring61by the groove61Z. The metal layer61D, for example, is a dummy pattern that decreases the difference between the shape of the conductive layer (wiring61, connecting portion61A, and metal layer61D) formed in the structural body41and the shape of the conductive layer (e.g., wiring67, connecting portion67A, and metal layer67D) formed in another structural body. The metal layer61D is formed at a position corresponding to the projection22(refer toFIG. 2) of the coil substrate20. In the present example, the metal layer61D is arranged at a position overlapping the connecting portion67A, which is formed in the uppermost structural body47of the coil substrate20, in a plan view. The metal layer61D is a (floating) portion electrically isolated so as not to be electrically connected to other wirings and metal layers in the coil substrate20subsequent to singulation.

The structure of the structural bodies stacked on the upper surface30B of the substrate30will now be described.

As illustrated inFIG. 4, an adhesive layer71is stacked on the upper surface30B of the substrate30. The adhesive layer71covers the upper inner side surface of the through hole30X exposed from the via wiring V1. Thus, the adhesive layer71is formed on the upper surface30B of the substrate30and is formed in the through hole30X. The adhesive layer71includes a through hole71X that extends through the adhesive layer71in the thickness direction and exposes a portion of the upper surface of the via wiring V1. The through hole71X extends from the upper surface of the adhesive layer71to the lower surface of the adhesive layer71formed in the through hole30X. In other words, the through hole71X communicates with a portion of the through hole30X, and a portion of the through hole71X is formed in the through hole30X. The planar shape of the through hole71X may have any shape and any size. The planar shape of the through hole71X is, however, smaller than the planar shape of the through hole30X. For example, the planar shape of the through hole71X is a circular shape having a diameter of approximately 140 to 180 μm.

The structural body42is stacked on the upper surface30B of the substrate30by way of the adhesive layer71. The wiring62and the metal layer62D are stacked on the adhesive layer71. As illustrated inFIG. 5, the wiring62is formed to be substantially C-shaped in a plan view. The wiring62is a portion of the helical coil and serves as a second-layer wiring (approximately ¾ of a winding) of the coil.

The wiring62includes a through hole62X that extends through the wiring62in the thickness direction and communicates with the through hole71X of the adhesive layer71. The planar shape of the through hole62X may have any shape and any size. The planar shape of the through hole62X, however, is smaller than the planar shape of the through hole30X. For example, the planar shape of the through hole62X may be a circular shape having a diameter of approximately 140 to 180 μm.

The metal layer62D is a dummy pattern similar to the metal layer61D. For example, the metal layer62D includes three metal layer portions. Two of the three metal layer portions are spaced apart from the wiring62by a groove62Z, and are formed at positions overlapping the connecting portions61A,67A (refer toFIG. 6) in a plan view. The remaining metal layer portion of the metal layer62D is spaced apart from the wiring62by a groove62Y, and is formed at a position overlapping a portion of the wiring61in a plan view.

As illustrated inFIG. 4, a portion of each side surfaces of the wiring62and the metal layer62D is covered with the adhesive layer71. In the present example, the grooves62Y,62Z illustrated inFIG. 5are filled with the adhesive layer71.

The insulation layer52is stacked on the adhesive layer71so as to cover the upper surfaces of the wiring62and the metal layer62D. The insulation layer52includes a through hole52X that extends through the insulation layer52in the thickness direction and communicates with the through holes62X,71X. The through hole52X exposes the upper surface of the wiring62around the through hole62X. Therefore, the planar shape of the through hole52X is larger than the planar shapes of the through holes62X,71X. For example, the planar shape of the through hole52X is a circular shape having a diameter of approximately 200 to 300 μm.

A via wiring V2is formed in the communication through holes52X,62X,71X. For example, the via wiring V2is formed on the via wiring V1exposed from the through hole71X, and all of the through holes52X,62X,71X are filled with the via wiring V2. Thus, the via wiring V2is formed to have a substantially T-shaped cross-section. The via wiring V2is connected to the wiring62defining the inner side surface of the through hole62X. The via wiring V2is also connected to the upper surface of the wiring62located at the periphery of through hole62X. The via wirings V1, V2serve as through electrodes that connect the wiring61(first-layer wiring) and the wiring62(second-layer wiring) in series. The via wirings V1, V2(through electrodes) extend through the insulation layer51, the substrate30, the adhesive layer71, the wiring62, and the insulation layer52.

The insulation layer52includes a through hole52Y that extends through the insulation layer52in the thickness direction to expose a portion of the upper surface of the wiring62. The planar shape of the through hole52Y may have any shape and any size. For example, the planar shape of the through hole52Y may be a circular shape having a diameter of approximately 200 to 300 μm.

The adhesive layer72is stacked on the insulation layer52. The structural body43is stacked on the adhesive layer72. Therefore, the wiring63and the metal layer63D are stacked on the adhesive layer72.

As illustrated inFIG. 5, the wiring63is formed to have a substantially elliptical shape in a plan view. A groove63Y that extends through the wiring63in the thickness direction is formed at a certain location in the wiring63. That is, the wiring63is cut in the widthwise direction by the groove63Y and formed to have a non-ring-like shape. The wiring63is a portion of the helical coil, and serves as a third-layer wiring (about one winding) of the coil.

The metal layer63D is a dummy pattern similar to the metal layer61D. For example, the metal layer63D includes two metal layer portions. The two metal layer portions are spaced apart from the wiring63by the groove63Z, and are formed at positions overlapping the connecting portions61A,67A (refer toFIG. 6) in a plan view.

As illustrated inFIG. 4, the adhesive layer72is partially formed in the through hole52Y, and covers the inner side surface of the through hole52Y. The adhesive layer72covers a portion of the side surfaces of the wiring63and the metal layer63D. In the present example, the grooves63Y,63Z illustrated inFIG. 5are filled with the adhesive layer72.

The adhesive layer72includes a through hole72X that extends through the adhesive layer72in the thickness direction and exposes a portion of the upper surface of the wiring62. The through hole72X extends from the upper surface of the adhesive layer72to the lower surface of the adhesive layer72formed in the through hole52Y. In other words, a portion of the through hole72X is located in the through hole52Y.

The wiring63includes a through hole63X that extends through the wiring63in the thickness direction and communicates with the through hole72X. The planar shapes of the through holes63X,72X may have any shape and any size. The planar shapes of the through holes63X,72X is smaller than the planar shape of the through hole52Y. For example, the planar shapes of the through holes63X,72X may be a circular shape having a diameter of approximately 140 to 180 μm.

The insulation layer53is stacked on the adhesive layer72to cover the upper surfaces of the wiring63and the metal layer63D. The insulation layer53includes a through hole53X that extends through the insulation layer53in the thickness direction and communicates with the through holes63X,72X. The through hole53X exposes the upper surface of the wiring63around the through hole63X. Therefore, the planar shape of the through hole53X may be larger than the planar shapes of the through holes63X,72X. For example, the planar shape of the through hole53X is a circular shape having a diameter of approximately 200 to 300 μm.

A via wiring V3is formed in the communication through holes53X,63X,72X. For example, the via wiring V3is formed on the wiring62exposed from the through hole72X, and the through holes53X,63X,72X are all filled with the via wiring V3. Thus, the via wiring V3is formed to have a substantially T-shaped cross-section. The via wiring V3is connected to the wiring63defining the inner side surface of the through hole63X. The via wiring V3is also connected to the upper surface of the wiring63around the through hole63X. The via wiring V3serves as a through electrode that connects the wiring62(second-layer wiring) and the wiring63(third-layer wiring) in series. The via wiring V3(through electrode) extends through the insulation layer52of the structural body42, the adhesive layer72, and the wiring63and the insulation layer53of the structural body43.

As illustrated inFIG. 5, the insulation layer53includes a through hole53Y that extends through the insulation layer53in the thickness direction and exposes a portion of the upper surface of the wiring63. The planar shape of the through hole53Y may have any shape and any size. For example, the planar shape of the through hole53Y may be a circular shape having a diameter of approximately 200 to 300 μm.

The adhesive layer73is stacked on the insulation layer53. The structural body44is stacked on the adhesive layer73. Therefore, the wiring64and the metal layer64D are stacked on the adhesive layer73. The insulation layer54is stacked on the adhesive layer73so as to cover the upper surfaces of the wiring64and the metal layer64D. The structural body44has the same structure as the structural body42, and for example, corresponds to the structure in which the structural body42is rotated by 180 degrees about a normal line on the upper surface of the insulation layer52.

The wiring64is formed to have a substantially C-shaped in a plan view. The wiring64is a portion of the helical coil, and serves as a fourth-layer wiring (about ¾ winding) of the coil. The metal layer64D is a dummy pattern similar to the metal layer62D. For example, the metal layer64D is spaced apart from the wiring64by a groove64Y or a groove64Z.

The adhesive layer73covers the inner side surface of the through hole53Y like the adhesive layer72. The adhesive layer73also covers a portion of the side surfaces of the wiring64and the metal layer64D. In the present example, the grooves64Y,64Z are filled with the adhesive layer73. The adhesive layer73includes a through hole73X that extends through the adhesive layer73in the thickness direction and exposes a portion of the upper surface of the wiring63. The through hole73X is formed at a position overlapping the through hole53Y in a plan view, and a portion of the through hole73X is located in the through hole53Y.

The wiring64includes a through hole64X that extends through the wiring64in the thickness direction and communicates with the through hole73X. The planar shapes of the through holes64X,73X are smaller than the planar shape of the through hole53Y.

The insulation layer54includes a through hole54X that extends through the insulation layer54in the thickness direction and communicates with the through holes64X,73X. The planar shape of the through hole54X is larger than the planar shapes of the through holes64X,73X. The insulation layer54also includes a through hole54Y that extends through the insulation layer54in the thickness direction and exposes a portion of the upper surface of the wiring64.

A via wiring V4(refer toFIG. 7) is formed in the communication through holes54X,64X,73X. For example, the via wiring V4is formed on the wiring63exposed from the through hole73X, and all of the through holes54X,64X,73X are filled with the via wiring V4. The via wiring V4serves as a through electrode that connects the wiring63(third-layer wiring) and the wiring64(fourth-layer wiring) in series. The via wiring V4(through electrode) extends through the insulation layer53of the structural body43, the adhesive layer73, and the wiring64and the insulation layer54of the structural body44.

As illustrated inFIG. 4, the adhesive layer74is stacked on the insulation layer54. The structural body45is stacked on the adhesive layer74. Therefore, the wiring65and the metal layer65D are stacked on the adhesive layer74. The insulation layer55is stacked on the adhesive layer74so as to cover the upper surfaces of the wiring65and the metal layer65D. As illustrated inFIGS. 5 and 6, the structural body45has the same structure as the structural body43, and corresponds to a structure in which the structural body43is rotated by 180 degrees about a normal line on the upper surface of the insulation layer53.

As illustrated inFIG. 6, the wiring65is formed to have a substantially elliptical shape in a plan view. A groove65Y that extends through the wiring65in the thickness direction is formed at a certain location in the wiring65. That is, the wiring65is cut in the widthwise direction by the groove65Y and formed to a have a non-ring-like shape. The wiring65is a portion of the helical coil and serves as a fifth-layer wiring (about one winding) of the coil. The metal layer65D is a dummy pattern similar to the metal layer61D (refer toFIG. 5), and is spaced apart from the wiring65by a groove65Z.

The adhesive layer74covers the inner side surface of the through hole54Y like the adhesive layer72(refer toFIG. 4). The adhesive layer74covers a portion of the side surfaces of the wiring65and the metal layer65D. In the present example, the grooves65Y,65Z are filled with the adhesive layer74. The adhesive layer74includes a through hole74X that extends through the adhesive layer74in the thickness direction and exposes a portion of the upper surface of the wiring64(refer toFIG. 5). The through hole74X is formed at a position overlapping the through hole54Y in a plan view, and a portion of the through hole74X is located in the through hole54Y.

The wiring65includes a through hole65X that extends through the wiring65in the thickness direction and communicates with the through hole74X. The planar shapes of the through holes65X,74X are smaller than the planar shape of the through hole54Y.

The insulation layer55includes a through hole55X that extends through the insulation layer55in the thickness direction and communicates with the through holes65X,74X. The planar shape of the through hole55X is larger than the planar shapes of the through holes65X,74X. The insulation layer55includes a through hole55Y that extends through the insulation layer55in the thickness direction and exposes a portion of the upper surface of the wiring65.

A via wiring V5(refer toFIG. 7) is formed in the communication through holes55X,65X,74X. For example, the via wiring V5is formed on the wiring64(refer toFIG. 5) exposed from the through hole74X, and the through holes55X,65X,74X are all filled with the via wiring V5. The via wiring V5serves as a through electrode that connects the wiring64(fourth-layer wiring) and the wiring65(fifth-layer wiring) in series. The via wiring V5(through electrode) extends through the insulation layer54of the structural body44, the adhesive layer74, and the wiring65and the insulation layer55of the structural body45.

The adhesive layer75is stacked on the insulation layer55. The structural body46is stacked on the adhesive layer75. Therefore, the wiring66and the metal layer66D are stacked on the adhesive layer75. The insulation layer56is stacked on the adhesive layer75so as to cover the upper surfaces of the wiring66and the metal layer66D. The structural body46has the same structure as the structural body42(refer toFIG. 5).

As illustrated inFIG. 6, the wiring66is formed to have a substantially C-shaped in a plan view. The wiring66is a portion of the helical coil, and is a sixth-layer wiring (about ¾ winding) of the coil. The metal layer66D is a dummy pattern similar to the metal layer62D (refer toFIG. 5). The metal layer66D is, for example, spaced apart from the wiring66by a groove66Y or a groove66Z.

As illustrated inFIG. 4, the adhesive layer75covers the inner side surface of the through hole55Y. The adhesive layer75also covers a portion of the respective side surfaces of the wiring66and the metal layer66D. In the present example, the grooves66Y,66Z (refer toFIG. 6) are filled with the adhesive layer75. The adhesive layer75includes a through hole75X that extends through the adhesive layer75in the thickness direction and exposes a portion of the upper surface of the wiring65. The through hole75X is formed at a position overlapping the through hole55Y in a plan view, and a portion of the through hole75X is located in the through hole55Y.

The wiring66includes a through hole66X that extends through the wiring66in the thickness direction and communicates with the through hole75X. The planar shapes of the through holes66X,75X are smaller than the planar shape of the through hole55Y.

The insulation layer56includes a through hole56X that extends through the insulation layer56in the thickness direction and communicates with the through holes66X,75X. The planar shape of the through hole56X is larger than the planar shapes of the through holes66X,75X. The insulation layer56includes a through hole56Y that extends through the insulation layer56in the thickness direction and exposes a portion of the upper surface of the wiring66.

A via wiring V6is formed in the communication through holes56X,66X,75X. For example, the via wiring V6is formed on the wiring65exposed from the through hole75X, and the through holes56X,66X,75X are all filled with the via wiring V6. The via wiring V6serves as a through electrode that connects the wiring65(fifth-layer wiring) and the wiring66(sixth-layer wiring). The via wiring V6(through electrode) extends through the insulation layer55of the structural body45, the adhesive layer75, and the wiring66and the insulation layer56of the structural body46.

The adhesive layer76is stacked on the insulation layer56. The structural body47is stacked on the adhesive layer76. Therefore, the wiring67, the connecting portion67A, and the metal layer67D are stacked on the adhesive layer76. The insulation layer57is stacked on the adhesive layer76so as to cover the upper surfaces of the wiring67, the connecting portion67A, and the metal layer67D.

As illustrated inFIG. 6, the planar shape of the wiring67is formed to have a substantially elliptical shape. A groove67Y that extends through the wiring67in the thickness direction is formed at a certain location in the wiring67. That is, the wiring67is cut in the widthwise direction by the groove67Y and formed to have a non-ring-like shape. The wiring67is a portion of the helical coil, and serves as a seventh-layer wiring (about one winding) of the coil.

The connecting portion67A is formed at one end of the wiring67. The connecting portion67A is formed at a position corresponding to the projection22(refer toFIG. 2) of the coil substrate20. The connecting portion67A is formed integrally with the wiring67. In other words, the connecting portion67A is a portion of the wiring67. The connecting portion67A is exposed from the insulation film25at a side surface20B (refer toFIG. 8A) of the coil substrate20subsequent to singulation. The connecting portion67A is connected to the electrode93of the inductor90(refer toFIG. 8B). The metal layer67D is a dummy pattern similar to the metal layer61D (refer toFIG. 5), and is spaced apart from the wiring67by a groove67Z.

As illustrated inFIG. 4, the adhesive layer76covers the inner side surface of the through hole56Y. The adhesive layer76also covers a portion of the respective side surfaces of the wiring67, the connecting portion67A, and the metal layer67D. In the present example, the grooves67Y,67Z (refer toFIG. 6) are filled with the adhesive layer76. The adhesive layer76includes a through hole76X that extends through the adhesive layer76in the thickness direction and exposes a portion of the upper surface of the wiring66. The through hole76X is formed at a position overlapping the through hole56Y in a plan view, and a portion of the through hole76X is located in the through hole56Y.

The wiring67includes a through hole67X that extends through the wiring67in the thickness direction and communicates with the through hole76X. The planar shapes of the through holes67X,76X are smaller than the planar shape of the through hole56Y.

The insulation layer57includes a through hole57X that extends through the insulation layer57in the thickness direction and communicates with the through holes67X,76X. The planar shape of the through hole57X is larger than the planar shapes of the through holes67X,76X.

A via wiring V7is formed in the communication through holes57X,67X,76X. For example, the via wiring V7is formed on the wiring66exposed from the through hole76X, and the through holes57X,67X,76X are all filled with the via wiring V7. The via wiring V7serves as a through electrode that connects the wiring66(sixth-layer wiring) and the wiring67(seventh-layer wiring) in series. The via wiring V7(through electrode) extends through the insulation layer56of the structural body46, the adhesive layer76, and the wiring67and the insulation layer57of the structural body47.

As illustrated inFIG. 6, the insulation layer57includes a through hole57Y that extends through the insulation layer57in the thickness direction and exposes a portion of the upper surface of the wiring67. The through hole57Y is filled by a via wiring V8(refer toFIG. 7). The wiring67is electrically connected to the via wiring V8.

The planar shapes of the through holes64X to67X,73X to76X may have any shape and any size. For example, the planar shapes of the through holes64X to67X,73X to76X may be a circular shape having a diameter of approximately 140 to 180 μm. The planar shapes of the through holes54X to57X,54Y to57Y that are larger than the planar shapes of the through holes64X to67X,73X to76X may be, for example, a circular shape having a diameter of approximately 200 to 300 μm. Furthermore, copper and copper alloy, for example, may be used as the material of the via wirings V1to V8illustrated inFIG. 7.

Thus, the wirings61to67of the structural bodies41to47adjacent in the thickness direction in the coil substrate20are connected in series by the via wirings V1to V8, as illustrated inFIG. 7, to form a helical coil from the connecting portion61A to the connecting portion67A. In other words, the connecting portion61A is arranged at one end of the helical coil, and the connecting portion67A is arranged at the other end of the helical coil.

As illustrated inFIG. 2, the through hole23X that extends through the stacked body23in the thickness direction is formed at a substantially central part in a plan view of the stacked body23. As illustrated inFIGS. 3 and 4, the side surfaces of the wirings61to67are exposed at the inner wall surface of the through hole23X.

The insulation film25covers the entire surface of the stacked body23. As illustrated inFIGS. 2 and 4, the insulation film25continuously covers the outer wall surface (side wall) of the stacked body23, the lower surface and the side surface of the wiring61located at the lowermost layer of the stacked body23, the upper surface of the insulation layer57located at the uppermost layer of the stacked body23, the upper surface of the via wiring V7, the upper surface of the via wiring V8(refer toFIG. 7), and the inner wall surface of the through hole23X. Therefore, the insulation film25covers the side surfaces of the wirings61to67exposed at the inner wall surface of the through hole23X. The insulation film25covers the side surface of the wiring61exposed in the grooves61Y,61Z. As illustrated inFIG. 2, for example, the insulation film25covers the upper surface and the lower surface of the stacked body23from the position overlapping the connecting portion67A in a plan view to the position overlapping the metal layer67D (connecting portion61A) in a plan view. In the present example, the insulation film25further covers a portion of the coupling portion12. The majority of the coupling portion12and the entire surface of the outer frame13are exposed from the insulation film25. The insulation layer57is not illustrated inFIG. 2. Further, the insulation film25on the stacked body23is not illustrated inFIG. 2.

For example, an insulative resin such as an epoxy-based resin, an acryl-based resin, and the like may be used as the material of the insulation film25. The insulation film25may contain a filler of silica, alumina, or the like. The thickness of the insulation film25is approximately 10 to 50 μm, for example.

The coil substrate20described above is coupled to the adjacent coil substrate20by the coupling portion12. The structure of the coupling portion12will be briefly described below.

As illustrated inFIG. 3, the insulation layer51and the metal layer81are sequentially stacked on the lower surface30A of the substrate30. The adhesive layer71, the metal layer82, the insulation layer52, the adhesive layer72, the metal layer83, the insulation layer53, the adhesive layer73, the metal layer84, the insulation layer54, the adhesive layer74, the metal layer85, the insulation layer55, the adhesive layer75, the metal layer86, the insulation layer56, the adhesive layer76, the metal layer87, and the insulation layer57are stacked in order on the upper surface30B of the substrate30. As illustrated inFIG. 4, the metal layer81is electrically connected to the metal layer61D and the connecting portion61A, the metal layer82is electrically connected to the metal layer62D, the metal layer83is electrically connected to the metal layer63D, and the metal layer84is electrically connected to the metal layer64D. Furthermore, the metal layer85is electrically connected to the metal layer65D, the metal layer86is electrically connected to the metal layer66D, and the metal layer87is electrically connected to the metal layer67D and the connecting portion67A. Copper and copper alloy, for example, may be used as the material of the metal layers81to87.

As illustrated inFIG. 2, a recognition mark12X is formed at the certain location in the coupling portion12. The recognition mark12X extends through the coupling portion12in the thickness direction. The recognition mark12X is used as an alignment mark, for example. The planar shape of the recognition mark12X may have any shape and any size. For example, the planar shape of the recognition mark12X is substantially circular.

The structure of the outer frame13will now be described.

As illustrated inFIG. 3, the outer frame13is formed only by the substrate30. The outer frame13is formed at the two end regions of the substrate30, for example. The outer frame13, for example, is formed by extending the substrate30to the outer side of the coupling portion12. In other words, only the substrate30projects to the outer side of the coupling portion12. The sprocket holes13X described above are formed in the outer frame13(substrate30). Each sprocket hole13X extends through the substrate30in the thickness direction.

FIG. 8Aillustrates the coil substrate singulated by cutting the insulation film25, the substrate30, the insulation layers51to57, the metal layers61D to67D, and the like at the cutting position illustrated by broken lines inFIG. 4. The connecting portion61A is exposed at one side surface20A of the coil substrate20. The connecting portion67A is exposed at the other side surface20B of the coil substrate20. Subsequent to the singulation, the coil substrate20may also be used upside down. Furthermore, the coil substrate20may be arranged at any angle subsequent to the singulation.

The structure of the inductor90including the coil substrate20will now be described.

As illustrated inFIG. 8B, the inductor90is a chip inductor including the coil substrate20, an encapsulation resin91that encapsulates the coil substrate20, and the electrodes92,93. The planar shape of the inductor90is, for example, substantially rectangular and approximately 1.6 mm×0.8 mm. The thickness of the inductor90is, for example, approximately 1.0 mm. The inductor90may be used, for example, in a voltage conversion circuit of a compact electronic device.

The encapsulation resin91encapsulates the coil substrate20excluding the side surface20A and the side surface20B. In other words, the encapsulation resin91entirely covers the coil substrate20(stacked body23and insulation film25) excluding the side surfaces20A,20B where the connecting portions61A,67A are exposed. The encapsulation resin91covers the upper surface and the lower surface of the insulation film25. The encapsulation resin91also covers the side surface of the insulation film25defining the inner wall surface of the through hole20X. In the present example, the through hole20X is filled with the encapsulation resin91. Therefore, the encapsulation resin91covers the entire inner wall surface of the through hole20X. The encapsulation resin91functions as a magnetic body. In other words, a magnetic material is used for the encapsulation resin91. The magnetic material is formed from magnetic powder and a resin that serves as a bonding material. For example, ferrite or a magnetic metal, such as iron or an iron-based alloy, may be used as the material of the magnetic powder. As the material of the bonding material, for example, a thermosetting resin such as an epoxy-based resin or a thermoplastic resin may be used. The magnetic material functions to increase the inductance of the inductor90.

Thus, in the inductor90, the through hole20X formed at substantially the central part of the coil substrate20is filled with the encapsulation resin91that functions as the magnetic body. Therefore, more portions around the coil substrate20may be encapsulated with the magnetic body (encapsulation resin91) compared to when the through hole20X is not formed. The inductance of the inductor90may thus be enhanced.

The core of the magnetic body such as the ferrite may be arranged in the through hole20X. In this case, the encapsulation resin91may be formed to encapsulate the coil substrate20together with the core of the magnetic body. The shape of the core of the magnetic body may be, for example, a circular column shape or a cuboid shape.

The electrode92is formed on the outer side of the encapsulation resin91, and is connected to a portion of the connecting portion61A. The electrode92continuously covers the side surface20A of the coil substrate20, the side surface of the encapsulation resin91formed flush with the side surface20A, and portions of the upper surface and the lower surface of the encapsulation resin91. The inner wall surface of the electrode92contacts the side surface of the connecting portion61A exposed at the side surface20A of the coil substrate20. Therefore, the electrode92is electrically connected to the connecting portion61A.

The electrode93is formed on the outer side of the encapsulation resin91, and is connected to a portion of the connecting portion67A. The electrode93continuously covers the side surface20B of the coil substrate20, the side surface of the encapsulation resin91formed flush with the side surface20B, and portions of the upper surface and the lower surface of the encapsulation resin91. The inner wall surface of the electrode93contacts the side surface of the connecting portion67A exposed at the side surface20B of the coil substrate20. Therefore, the electrode93is electrically connected to the connecting portion67A.

Copper and copper alloy, for example, may be used as the material of the electrodes92,93. The electrodes92,93may have a stacked structure including a plurality of metal layers.

The electrodes92,93are also connected to the metal layers51D to67D arranged as dummy patterns. However, the metal layers61D to67D are not electrically connected to the wirings61to67and the other metal layers. The metal layers61D to67D are electrically isolated. Thus, the wirings61to67are not short-circuited by the metal layers61D to67D and the electrodes92,93.

A method for manufacturing the coil substrate10will now be described.

First, in the step illustrated inFIG. 9, the substrate100is prepared. The substrate100includes a plurality of substrates30, each having a block11and an outer frame13. Each block11includes a plurality of individual regions A1and a coupling portion12that surrounds the individual regions A1. The outer frame13is arranged at two ends (upper end and lower end inFIG. 9) of the substrate100. The outer frame13includes a plurality of sprocket holes13X that extends through the substrate30in the thickness direction. The sprocket holes13X are arranged at substantially constant intervals in the longitudinal direction (lateral direction inFIG. 9) of the substrate100. The sprocket holes13X may be formed in, for example, a pressing process or a laser cutting process. The sprocket holes13X are through holes for conveying the substrate100. When the substrate100is attached to the manufacturing device, the sprocket holes13X are engaged with the pins of the sprocket driven by the motor or the like to convey the substrate100at the pitch of the sprocket holes13X.

The substrate100may be a reel-like (tape-like) flexible insulative resin film. The width of the substrate100(length in the direction orthogonal in a plan view to the arraying direction of the sprocket holes13X) is determined in accordance with the manufacturing device on which the substrate100is mounted. For example, the width of the substrate100may be approximately 40 to 90 mm. The substrate100may have any length. In the example illustrated inFIG. 9, the individual regions A1are arranged in 6 rows and 2 columns in each substrate30. However, each substrate30may be lengthened to provide, for example, several hundred columns of the individual regions A1. The reel-like substrate100is cut along the cutting position A2and divided into a plurality of sheet-like coil substrates10.

Hereinafter, the manufacturing of a single individual region A1(illustrated by dashed lines inFIG. 9) of one substrate will be described for the sake of convenience.

In the steps illustrated inFIGS. 10A and 10B, the insulation layer51is stacked, in a semi-cured state, on the lower surface30A of the substrate30in the region (i.e., block11) excluding the outer frame13. For example, the insulation layer51covers the entire lower surface30A of the substrate30at the position of the block11. For example, when using the insulative resin film for the insulation layer51, the insulative resin film is laminated onto the lower surface30A of the substrate30. In this step, however, the insulative resin film is not thermally cured and is in the B-stage state (semi-cured state). The insulative resin film is laminated in the vacuum atmosphere to limit the formation of voids in the insulation layer51. When using a liquid insulative resin or an insulative resin paste for the insulation layer51, the liquid insulative resin or the insulative resin paste is, for example, applied to the lower surface30A of the substrate30by a printing process or a spin coating process. Then, the liquid insulative resin or the insulative resin paste is pre-baked to the B-stage state.

Then, the through hole30X is formed in the substrate30at the position of the individual region A1. Furthermore, the through hole51X, which is in communication with the through hole30X, is formed in the insulation layer51at the position of the individual region A1. The through holes30X,51X can be formed through a pressing process or a laser cutting process, for example. The sprocket holes13X may be formed in this step. In other words, the through holes30X,51X and the sprocket holes13X may be formed in the same step.

Next, in the step illustrated inFIG. 11A, a metal foil161is stacked on the lower surface of the semi-cured insulation layer51. The metal foil161covers, for example, the entire lower surface of the insulation layer51. For example, the metal foil161is laminated onto the lower surface of the semi-cured insulation layer51by thermal compression bonding. Then, a thermal curing process is performed under a temperature atmosphere of approximately 150° C. to cure the semi-cured insulation layer51. When the insulation layer51is cured, the substrate30is adhered to the upper surface of the insulation layer51, and the metal foil161is adhered to the lower surface of the insulation layer51. In other words, the insulation layer51functions as an adhesive for adhering the substrate30and the metal foil161. The metal foil161is patterned in a subsequent step to form the wiring61, the connecting portion61A, and the like. Copper foil, for example, may be used as the metal foil161.

Then, the via wiring V1is formed on the metal foil161exposed in the through hole51X. In this step, the through hole51X and a portion of the through hole30X are filled with the via wiring V1. For example, a plated film is deposited in the through holes30X,51X through electrolytic plating using the metal foil161as a power supplying layer to form the via wiring V1. Alternatively, a metal paste of copper or the like may be applied to the metal foil161exposed in the through hole51X to form the via wiring V1.

Next, as illustrated inFIGS. 11B and 11C, the metal foil161is patterned to form the metal layer61E on the lower surface of the insulation layer51at the position of the individual region A1. The patterning of the metal foil161forms the connecting portion61A at one end of the metal layer61E and the metal layer61D, which serves as the dummy pattern. As a result, the structural body41including the insulation layer51, the metal layer61E, and the connecting portion61A is stacked on the lower surface30A of the substrate30. The metal layer61E formed in this step has a larger planar shape than the wiring61(portion of helical coil) illustrated inFIG. 7, for example. The metal layer61E is ultimately punched out to form the first-layer wiring61(approximately one winding) of the helical coil. Furthermore, in this step, the metal layer81, which is connected to the connecting portion61A and the metal layer61D, is formed on the lower surface of the insulation layer51at the position of the coupling portion12. In other words, in this step, the metal foil161illustrated inFIG. 11Ais patterned to form an opening201Y and the grooves61Y,61Z, as illustrated inFIG. 11C. The groove61Y enables the helical shape of the coil to be easily formed when shaping the coil substrate20in a subsequent step. The metal layer81formed in this step is used as a power supplying layer when performing electrolytic plating in a subsequent step. If electrolytic plating is not performed in a subsequent step, the formation of the metal layer81may be omitted. InFIG. 11C, the insulation layer51exposed from the opening201Y and the grooves61Y,61Z is shaded.

The patterning of the metal foil161is performed, for example, using a wiring forming process such as a subtractive process. For example, the photosensitive resist is applied to the lower surface of the metal foil161, and a predetermined region is exposed and developed to form an opening in the resist. Then, the metal foil161exposed from the opening is etched and removed. This integrally forms the metal layer61E, the connecting portion61A, the metal layer61D, and the metal layer81.

In the step illustrated inFIG. 12A, a support film102(support member) having a structure similar to the substrate100is first prepared. In other words, the support film102includes a block11with a plurality of individual regions A1, and an outer frame13projecting out to the outer side of the block11. A reel-like (tape-like) flexible insulative resin film may be used, for example, for the support film102. For example, polyphenylene sulfide (PPS), polyimide film, polyethylene naphtalate film, and the like may be used as the support film102. The thickness of the support film102is, for example, approximately 12 to 50 μm.

Then like the steps illustrated inFIGS. 9 to 11A, the structural body42including the insulation layer52and the metal layer62E is stacked on a lower surface102A of the support film102. For example, after forming the sprocket hole102X in the support film102at the position of the outer frame13, the insulation layer52in the semi-cured state is stacked on the lower surface102A of the support film102at a position other than the outer frame13. Then, as illustrated inFIG. 12B, the through holes52X,52Y that extend through the support film102and the insulation layer52in the thickness direction are formed through a pressing process or a laser cutting process. Then, the metal foil is stacked on the lower surface of the semi-cured insulation layer52, and the metal foil is patterned by the subtractive method. As illustrated inFIGS. 12B and 12C, the metal layer62E is formed on the lower surface of the insulation layer52at the position of the individual region A1, and the metal layer62D serving as the dummy pattern is formed by patterning the metal foil. The metal layer82, which is connected to the metal layer62D, is formed on the lower surface of the insulation layer52at the position of the coupling portion12. In other words, in this step, an opening202Y and the grooves62Y,62Z are formed by patterning the metal foil stacked on the lower surface of the insulation layer52. The metal layer62E formed in this step has a larger planar shape than the wiring62(part of helical coil) illustrated inFIG. 7, for example. The metal layer62E is ultimately punched out or the like to form the second-layer wiring62(approximately ¾ of a winding) of the helical coil. The metal layer62E is separated from the metal layer82by the opening202Y and the groove62Z. The groove62Y enables the helical shape of the coil to be easily formed when shaping the coil substrate20in a subsequent step. InFIG. 12C, the insulation layer52exposed from the opening202Y and the grooves62Y,62Z is shaded.

The sprocket holes102X are through hole for conveying the support film102like the sprocket holes13X. When the support film102is attached to the manufacturing device, the sprocket holes102X engage with the pins of the sprocket driven by a motor or the like to convey the support film102at the pitch between the sprocket holes102X.

First, in the step illustrated inFIG. 13A, the adhesive layer71in the semi-cured state that covers the entire surfaces (lower surface and side surface) of the metal layers62D,62E,82is stacked on the lower surface of the insulation layer52. The grooves62Y,62Z and the opening202Y (refer toFIG. 12A) are filled with the adhesive layer71. For example, when using the insulative resin film for the adhesive layer71, the insulative resin film is laminated to the lower surface of the insulation layer52by thermal compression bonding. The thermal compression bonding may be performed by pressing the insulative resin film at a predetermined pressure (e.g., approximately 0.5 to 0.6 MPa) under a vacuum atmosphere. In this step, however, the insulative resin film is not thermally cured and is in the B-stage state (semi-cured state). Alternatively, when using the liquid insulative resin or the insulative resin paste for the adhesive layer71, the liquid insulative resin or the insulative resin paste is applied to the lower surface of the insulation layer52, for example, by a printing process or a spin coating process. Then, the liquid insulative resin or the insulative resin paste is pre-baked to the B-stage state. The insulative resin having high fluidity is preferably used, for example, for the material of the adhesive layer71. The grooves62Y,62Z and the opening202Y may be filled by such insulative resin having high fluidity.

In the step illustrated inFIG. 13B, the through hole62X is formed in the metal layer62E, which is exposed from the through hole52X, and the through hole71X, which is in communication with the through hole62X, is formed in the adhesive layer71. The through holes62X,71X have smaller planar shapes than the through hole52X. In the present example, the through holes52X,62X,71X have a circular shape, and the diameter of the through holes62X,71X is smaller than the diameter of the through hole52X. The upper surface of the metal layer62E around the through hole62X is thereby exposed from the through hole52X. The through holes62X,71X may be formed through a pressing process or a laser cutting process, for example.

When the structural body42is stacked on the upper surface30B of the substrate30, the through holes52X,62X,71X are formed at positions overlapping the through hole30X in a plan view, as illustrated inFIG. 13C. The upper surface of the metal layer62E is exposed from the through hole52Y.

In the step illustrated inFIG. 13C, the structure illustrated inFIG. 13B(i.e., structure in which the structural body42and the adhesive layer71are stacked in order on the lower surface102A of the support film102) is arranged on the upper side of the structure in which the structural body41is stacked on the lower surface30A of the substrate30. In this case, the adhesive layer71is arranged faced downward to the upper surface30B of the substrate30.

Then, in the step illustrated inFIG. 14A, the structural body42is stacked on the upper surface30B of the substrate30by way of the adhesive layer71so that the structural body41and the support film102are arranged at the outer side. For example, the structure illustrated inFIG. 14Ais hot pressed from above and below through vacuum pressing or the like. The adhesive layer71in the semi-cured state is then pressed and spread in the planar direction by the lower surface of the metal layer62E and the upper surface30B of the substrate30. When using the insulative resin having high fluidity as the material of the adhesive layer71in this case, the adhesive layer71that spreads in the planar direction may leak into the through hole71X and close the through hole71X. In such a case, the entire upper surface of the via wiring V1exposed from the through hole30X will be covered by the adhesive layer71, and the via wiring V2connected to the via wiring V1cannot be formed in a subsequent step. Thus, the through hole30X of the substrate30is formed to have a larger diameter than the through hole71X of the adhesive layer71in the present example. The pressure applied to the adhesive layer71around the through hole30X is thus small to reduce leakage of the adhesive layer71into the through hole71X. In other words, hot pressing limits reduction in the size of the planar shape of the through hole71X. Furthermore, a portion of the adhesive layer71spreads into the through hole30X in the present step, and the spread adhesive layer71covers the upper inner side surface of the through hole30X exposed from the via wiring V1. As a result, a portion of the through hole71X is formed in the through hole30X. In the hot pressing of the present step, the structure illustrated inFIG. 14Xis pressed from above and below with a pressure (e.g., approximately 0.2 to 0.6 MPa) that is the same as or smaller than the pressure of when laminating the adhesive layer71to the lower surface of the insulation layer52.

Then, the adhesive layer71is cured. This maintains the through hole71X, the through hole62X, and the through hole52X in communication. A portion of the upper surface of the via wiring V1is thus exposed from the through hole71X.

In the steps illustrated inFIGS. 12A to 14A, the through holes62X,71X may be formed after stacking the structural body42on the upper surface30B of the substrate30by way of the adhesive layer71.

In the step illustrated inFIG. 14B, the support film102illustrated inFIG. 14Ais removed from the insulation layer52. For example, the support film102is mechanically removed from the insulation layer52.

Then, the via wiring V2is formed on the via wiring V1exposed from the through hole71X. The through holes71X,62X,52X are filled with the via wiring V2. In this case, the through hole52X has a larger diameter than the through holes71X,62X. Thus, the via wiring V2also forms on a portion of the upper surface of the metal layer62E. This connects the via wiring V2to the side surface of the metal layer62E defining the inner side surface of the through hole62X and the upper surface of the metal layer62E around the through hole62X. As a result, the metal layer61E and the metal layer62E are connected in series by the via wirings V1, V2. In this step, for example, the upper surface of the via wiring V2is formed to be substantially flush with the upper surface of the insulation layer52. The via wiring V2may be formed by performing electrolytic plating that uses both of the metal layer81and the metal layer61E as the power supplying layers or by filling metal paste or the like. When forming the via wiring V2, the metal layer62E exposed from the through hole52Y is masked so that a plated film does not form on the through hole52Y.

In the manufacturing steps described above, the metal layer61E is connected in series to the metal layer62E by the via wiring V1, V2in the stacked structure including the structural body41stacked on the lower surface30A of the substrate30and the structural body42stacked on the upper surface30B of the substrate30. The series conductor of the metal layers61E,62E and the via wirings V1, V2corresponds to the portion of an approximately (1+¾) winding of the helical coil.

In the step illustrated inFIG. 15A, the structural body43including the insulation layer53and the metal layer63E is stacked on a lower surface103A of a support film103(support member), and the adhesive layer72is then stacked on the structural body43. This step may be performed in the same manner as the steps illustrated inFIGS. 12A to 13B. The step ofFIG. 15Aand the steps illustrated inFIGS. 12A to 13Bdiffer only in the position of the through hole and the shape of the metal layer (wiring) after patterning the metal foil. Thus, detailed description of the manufacturing method in the step ofFIG. 15Awill be omitted. The shape, thickness, material, and the like of the support film103and the support films104to105(support members) used in subsequent steps are similar to the support film102illustrated inFIG. 12A. Sprocket holes103X to107X formed in the outer frame13of each support film103to107are also similar to the sprocket holes102X of the support film102.

The structure illustrated inFIG. 15Aincludes the through holes53X,53Y that extend through the support film103and the insulation layer53in the thickness direction, and the through holes63X,72X that extend through the metal layer63E and the adhesive layer72in the thickness direction and communicate with the through hole53X. The through hole53X has a larger diameter than the through holes63X,72X. Thus, the upper surface of the metal layer63E around the through hole63X is exposed from the through hole53X. As illustrated inFIG. 15B, the metal layer63E, the metal layer63D, and the metal layer83are formed on the lower surface of the insulation layer53. The metal layer63E is separated from the metal layers63D,83by an opening203Y and the groove63Z. The groove63Y formed in the metal layer63E enables the helical shape of the coil to be easily formed when shaping the coil substrate20in a subsequent step. The metal layer63E, for example, has a larger planar shape than the wiring63illustrated inFIG. 7. The metal layer63E is ultimately punched out or the like to form the third-layer wiring63(about one winding) of the helical coil. As illustrated inFIG. 15A, the adhesive layer72is formed on the lower surface of the insulation layer53so as to cover the lower surface and the side surface of the metal layer63E, and fill the opening203Y, the groove63Y, and the groove63Z (refer toFIG. 15B). InFIG. 15B, the illustration of the adhesive layer72is omitted, and the insulation layer53exposed from the opening203Y and the grooves63Y,63Z is illustrated shaded.

The steps illustrated inFIGS. 16A to 16Cwill now be described.FIGS. 16A to 16Care cross-sectional views taken along line15a-15ainFIG. 15B.

First, in the step illustrated inFIG. 16A, the structural body43and the support film103are stacked on the insulation layer52of the structural body42through the adhesive layer72so that the structural body41and the support film103are arranged on the outer side like the step illustrated inFIG. 14A. In this case, the through hole52Y of the insulation layer52has a larger diameter than the through hole72X of the adhesive layer72. Thus, leakage of the adhesive layer72into the through hole72X may be like the adhesive layer71. The inner side surface of the through hole52Y is covered by the adhesive layer72. As a result, a portion of the through hole72X of the adhesive layer72forms in the through hole52Y. Furthermore, the through hole72X, the through hole63X, and the through hole53X are communicated, and the metal layer62E is exposed from the through hole72X.

In the step illustrated inFIG. 16B, the support film103illustrated inFIG. 16Ais removed from the insulation layer53. For example, the support film103is mechanically removed from the insulation layer53.

Then, in the step illustrated inFIG. 16C, the via wiring V3is formed in the same manner as the step illustrated inFIG. 14B. The through holes72X,63X,53X are filled with the via wiring V3. The via wiring V3is connected to the side surface of the metal layer63E defining the inner side surface of the through hole63X, the upper surface of the metal layer63E around the through hole63X, and the upper surface of the metal layer62E exposed from the through hole72X. As a result, the metal layer62E and the metal layer63E are connected in series by the via wiring V3. In this step, for example, the upper surface of the via wiring V3is formed to be substantially flush with the upper surface of the insulation layer53. The via wiring V3, for example, may be formed by performing electrolytic plating that uses both of the metal layer81and the metal layer61E as the power supplying layers or by filling metal paste or the like.

In the manufacturing steps described above, the metal layers61E,62E,63E are connected in series by the via wirings V1to V3in the stacked structure including the structural body41, the substrate30, the structural body42, and the structural body43. The series conductor of the metal layers61E,62E,63E and the via wirings V1to V3corresponds to the portion of an approximately (2+¾) winding of the helical coil.

In the steps illustrated inFIGS. 15A to 16B, the through holes63X,72X may be formed after stacking the structural body43on the structural body42by way of the adhesive layer72.

In the step illustrated inFIG. 17A, the structural body44including the insulation layer54and the metal layer64E is stacked on a lower surface104A of the support film104. This step can be performed in the same manner as the steps illustrated inFIGS. 12A to 13B. Thus, detailed description of the manufacturing method in the step ofFIG. 17Awill be omitted.

The structure illustrated inFIG. 17Aincludes the through holes54X,54Y that extend through the support film104and the insulation layer54in the thickness direction, and the through holes64X,73X that extend through the metal layer64E and the adhesive layer73in the thickness direction and communicate with the through hole54X. The through hole54X has a larger diameter than the through holes64X,73X. Thus, the upper surface of the metal layer64E around the through hole64X is exposed from the through hole54X. The metal layer64E, the metal layer64D, and the metal layer84are formed on the lower surface of the insulation layer54. As illustrated inFIG. 17B, the metal layer64E is separated from the metal layers64D,84by an opening204Y and the groove64Z. The groove64Y formed in the metal layer64E enables the helical shape of the coil to be easily formed when shaping the coil substrate20in a subsequent step. The metal layer64E has a larger planar shape than the wiring64illustrated inFIG. 7, for example. The metal layer64E is ultimately punched out or the like to form the fourth-layer wiring64(approximately ¾ winding) of the helical coil. Furthermore, as illustrated inFIG. 17A, the adhesive layer73is formed on the lower surface of the insulation layer54so as to cover the lower surface and the side surface of the metal layer64E and to fill the opening204Y (refer toFIG. 17B) and the grooves64Y,64Z. InFIG. 17B, the illustration of the adhesive layer73is omitted, and the insulation layer54exposed from the opening204Y and the grooves64Y,64Z is illustrated shaded.

The steps illustrated inFIGS. 18A and 18Bwill now be described.FIGS. 18A and 18Bare cross-sectional views taken along line17a-17ainFIG. 17B.

First, in the step illustrated inFIG. 18A, the structural body44and the support film104are stacked on the insulation layer53of the structural body43by way of the adhesive layer73so that the structural body41and the support film104are arranged on the outer side. In this case, the through hole53Y of the insulation layer53has a larger diameter than the through hole73X of the adhesive layer73. Thus, leakage of the adhesive layer73into the through hole73X may be limited like the adhesive layer71. The inner side surface of the through hole53Y is covered by the adhesive layer73. As a result, a portion of the through hole73X of the adhesive layer73is formed in the through hole53Y. Furthermore, the through hole73X, the through hole64X, and the through hole54X are communicated, and the metal layer63E is exposed from the through hole73X. The support film104is then removed from the insulation layer54.

Then, in the step illustrated inFIG. 18B, the via wiring V4is formed like the step illustrated inFIG. 14B. The through holes73X,64X,54X are filled with the via wiring V4. Thus, the via wiring V4is connected to the side surface of the metal layer64E defining the inner side surface of the through hole64X, the upper surface of the metal layer64E around the through hole64X, and the upper surface of the metal layer63E exposed from the through hole73X. As a result, the metal layer63E and the metal layer64E are connected in series by the via wiring V4. In this step, for example, the upper surface of the via wiring V4is formed to be substantially flush with the upper surface of the insulation layer54. The via wiring V4is, for example, formed by performing electrolytic plating that uses both of the metal layer81and the metal layer61E as the power supplying layers or by filling metal paste or the like.

In the manufacturing steps described above, the metal layers61E,62E,63E,64E are connected in series by the via wirings V1to V4in the stacked structure including the structural body41, the substrate30, and the structural bodies42to44. The series conductor of the metal layers61E,62E,63E,64E and the via wirings V1to V4corresponds to the portion of approximately three windings of the helical coil.

In the steps illustrated inFIGS. 17A and 18A, the through holes64X,73X may be formed after stacking the structural body33on the structural body43through the adhesive layer73.

In the step illustrated inFIG. 19A, the structural body45including the insulation layer55and the metal layer65E is stacked on a lower surface105A of the support film105. This step can be performed in the same manner as the steps illustrated inFIGS. 12A to 13B. Thus, detailed description of the manufacturing method in the step ofFIG. 19Awill be omitted.

The structure illustrated inFIG. 19Aincludes the through holes55X,55Y that extend through the support film105and the insulation layer55in the thickness direction, and the through holes65X,74X that extend through the metal layer65E and the adhesive layer74in the thickness direction and communicate with the through hole55X. The through hole55X has a larger diameter than the through holes65X,74X. Thus, the upper surface of the metal layer65E around the through hole65X is exposed from the through hole55X. Furthermore, as illustrated inFIG. 19B, the metal layer65E, the metal layer65D, and the metal layer85are formed on the lower surface of the insulation layer55. The metal layer65E is separated from the metal layers65D,85by an opening205Y and the groove65Z. The groove65Y formed in the metal layer65E enables the helical shape of the coil to be easily formed when shaping the coil substrate20in a subsequent step. The metal layer65E has a larger planar shape than the wiring65illustrated inFIG. 7, for example. The metal layer65E is ultimately punched out or the like to form the fifth-layer wiring65(about one winding) of the helical coil. As illustrated inFIG. 19A, the adhesive layer74is formed on the lower surface of the insulation layer55to cover the lower surface and the side surface of the metal layer65E and fill the opening205Y, the groove65Y, and the groove65Z (refer toFIG. 19B). InFIG. 19B, the illustration of the adhesive layer74is omitted, and the insulation layer55exposed from the opening205Y and the grooves65Y,65Z is illustrated shaded.

The steps illustrated inFIGS. 20A and 20Bwill now be described.FIGS. 20A and 20Bare cross-sectional views taken along line19a-19ainFIG. 19B.

First, in the step illustrated inFIG. 20A, the structural body45and the support film105are stacked on the insulation layer54of the structural body44through the adhesive layer74so that the structural body41and the support film105are arranged on the outer side like the step illustrated inFIG. 14A. In this case, the through hole54Y of the insulation layer54has a larger diameter than the through hole74X of the adhesive layer74. Thus, the leakage of the adhesive layer74into the through hole74X may be limited like the adhesive layer71. The inner side surface of the through hole54Y is covered by the adhesive layer74. As a result, a portion of the through hole74X of the adhesive layer74forms in the through hole54Y. Furthermore, the through hole74X, the through hole65X, and the through hole55X are communicated, and the metal layer64E is exposed from the through hole74X. The support film105is then removed from the insulation layer55.

In the step illustrated inFIG. 20B, the via wiring V5is formed like the step illustrated inFIG. 14B. The through holes74X,65X,55X are filled with the via wiring V5. Thus, the via wiring V5is connected to the side surface of the metal layer65E defining the inner side surface of the through hole65X, the upper surface of the metal layer65E around the through hole65X, and the upper surface of the metal layer64E exposed from the through hole74X. As a result, the metal layer64E and the metal layer65E are connected in series by the via wiring V5. In this step, for example, the upper surface of the via wiring V5is formed to be substantially flush with the upper surface of the insulation layer55. The via wiring V5can be formed through methods such as electrolytic plating that uses both of the metal layer81and the metal layer61E as power supplying layers or by filling metal paste or the like.

In the manufacturing steps described above, the metal layers61E,62E,63E,64E,65E are connected in series by the via wirings V1to V5in the stacked structure including the structural body41, the substrate30, and the structural bodies42to45. The series conductor of the metal layers61E,62E,63E,64E,65E and the via wirings V1to V5corresponds to the portion of approximately four windings of the helical coil.

In the steps illustrated inFIGS. 19A and 20A, the through holes65X,74X may be formed after stacking the structural body45on the structural body44through the adhesive layer74.

In the step illustrated inFIG. 21A, the structural body46including the insulation layer56and the metal layer66E is stacked on a lower surface106A of the support film106. This step can be performed in the same manner as the steps illustrated inFIGS. 12A to 13B. Thus, detailed description of the manufacturing method in the step ofFIG. 21Awill be omitted.

The structure illustrated inFIG. 21Aincludes the through holes56X,56Y that extend through the support film106and the insulation layer56in the thickness direction, and the through holes66X,75X that extend through the metal layer66E and the adhesive layer75in the thickness direction and communicate with the through hole56X. The through hole56X has a larger diameter than the through holes66X,75X. Thus, the upper surface of the metal layer66E around the through hole665X is exposed from the through hole56X. Furthermore, as illustrated inFIG. 21B, the metal layer66E, the metal layer66D, and the metal layer86are formed on the lower surface of the insulation layer56. The metal layer66E is separated from the metal layers66D,86by an opening206Y and the groove65Z. The groove66Y formed in the metal layer66E enables the helical shape of the coil to be easily formed when shaping the coil substrate20in a subsequent step. The metal layer66E has a larger planar shape than the wiring66illustrated inFIG. 7, for example. The metal layer66E is ultimately punched out or the like to form the sixth-layer wiring66(about ¾ winding) of the helical coil. As illustrated inFIG. 21A, the adhesive layer75is formed on the lower surface of the insulation layer56to cover the lower surface and the side surface of the metal layer66E and fill the opening206Y (refer toFIG. 21B) and the grooves66Y,66Z. InFIG. 21B, the illustration of the adhesive layer75is omitted, and the insulation layer56exposed from the opening206Y and the grooves66Y,66Z is illustrated shaded.

The steps illustrated inFIGS. 22A and 22Bwill now be described.FIGS. 22A and 22Bare cross-sectional views taken along line21a-21ainFIG. 21B.

First, in the step illustrated inFIG. 22A, the structural body46and the support film106are stacked on the insulation layer55of the structural body45through the adhesive layer75so that the structural body41and the support film106are arranged on the outer side like the step illustrated inFIG. 14A. In this case, the through hole55Y of the insulation layer55has a larger diameter than the through hole75X of the adhesive layer75. Thus, the leakage of the adhesive layer75into the through hole75X may be limited like the adhesive layer71. The inner side surface of the through hole55Y is covered by the adhesive layer75. As a result, a portion of the through hole75X of the adhesive layer75is formed in the through hole55Y. Furthermore, the through hole75X, the through hole66X, and the through hole56X are communicated, and the metal layer65E is exposed from the through hole75X. The support film106is then removed from the insulation layer56.

In the step illustrated inFIG. 22B, the via wiring V6is formed like the step illustrated inFIG. 14A. The through holes75X,66X,56X are filled with the via wiring V6. Thus, the via wiring V6is connected to the side surface of the metal layer66E defining the inner side surface of the through hole66X, the upper surface of the metal layer66E around the through hole66X, and the upper surface of the metal layer65E exposed from the through hole75X. As a result, the metal layer65E and the metal layer66E are connected in series by the via wiring V6. In this step, for example, the upper surface of the via wiring V6is formed to be substantially flush with the upper surface of the insulation layer56. The via wiring V6can be formed through methods such as electrolytic plating that uses both of the metal layer81and the metal layer61E as power supplying layers or by filling metal paste and the like.

In the manufacturing steps described above, the metal layers61E,62E,63E,64E,65E,66E are connected in series by the via wirings V1to V6in the stacked structure including the structural body41, the substrate30, and the structural bodies42to46. The series conductor portion of the metal layers61E,62E,63E,64E,65E,66E and the via wirings V1to V6corresponds to the portion of approximately (4+¾) windings of the helical coil.

In the steps illustrated inFIGS. 21A and 22A, the through holes66X,75X may be formed after stacking the structural body46on the structural body45through the adhesive layer75.

In the step illustrated inFIG. 23A, the structural body47including the insulation layer57and the metal layer67E is stacked on a lower surface107A of the support film107. This step can be performed in the same manner as the steps illustrated inFIGS. 12A to 13B. Thus, detailed description of the manufacturing method in the step ofFIG. 23Awill be omitted.

The structure illustrated inFIG. 23Bincludes the through holes57X,57Y that extend through the support film107and the insulation layer57in the thickness direction, and the through holes67X,76X that extend through the metal layer67E and the adhesive layer76in the thickness direction and communicate with the through hole57X. The through hole57X has a larger diameter than the through holes67X,76X. Thus, the upper surface of the metal layer67E around the through hole67X is exposed from the through hole57X. Furthermore, as illustrated inFIG. 23C, the metal layer67E, the connecting portion67A, the metal layer67D, and the metal layer87are formed on the lower surface of the insulation layer57. The metal layer67E is separated from the metal layers67D,87by the opening207Y and the groove67Z. The groove67Y formed in the metal layer67E enables the helical shape of the coil to be easily formed when shaping the coil substrate20in a subsequent step. The metal layer67E has a larger planar shape than the wiring67illustrated inFIG. 7, for example. The metal layer67E is ultimately punched out or the like to form the seventh-layer wiring67(about one winding) of the helical coil. As illustrated inFIGS. 23A and 23B, the adhesive layer76is formed on the lower surface of the insulation layer57to cover the lower surface and the side surface of the metal layer67E and fill the opening207Y and the grooves67Y,67Z. InFIG. 23C, the illustration of the adhesive layer76is omitted, and the insulation layer57exposed from the opening207Y and the grooves67Y,67Z is illustrated shaded.

First, in the step illustrated inFIG. 24A, the structural body47and the support film107are stacked on the insulation layer56of the structural body46through the adhesive layer76so that the structural body41and the support film107are arranged on the outer side like the step illustrated inFIG. 14A. In this case, the through hole56Y of the insulation layer56has a larger diameter than the through hole76X of the adhesive layer76. Thus, the leakage of the adhesive layer76into the through hole76X may be limited like the adhesive layer71. The inner side surface of the through hole56Y is covered by the adhesive layer76. As a result, a portion of the through hole76X of the adhesive layer76is formed in the through hole56Y. Furthermore, the through hole76X, the through hole67X, and the through hole57X are communicated, and the metal layer66E is exposed from the through hole76X. The support film107illustrated inFIG. 24Ais then removed from the insulation layer57in the step illustrated inFIG. 24B.

In the steps illustrated inFIGS. 25A and 25B, the via wiring V7is formed like the step illustrated inFIG. 14B. The through holes76X,67X,57X are filled with the via wiring V7. Thus, the via wiring V7is connected to the side surface of the metal layer67E defining the inner side surface of the through hole67X, the upper surface of the metal layer67E around the through hole67X, and the upper surface of the metal layer66E exposed from the through hole76X. As a result, the metal layer66E and the metal layer67E are connected in series by the via wiring V7. Furthermore, the via wiring V8that fills the through hole57Y is formed, as illustrated inFIG. 25B. The metal layer67E is thus electrically connected to the via wiring V8. In this step, for example, the upper surfaces of the via wirings V7, V8are formed to be substantially flush with the upper surface of the insulation layer57. The via wirings V7, B8can be formed through methods such as electrolytic plating that uses both of the metal layer81and the metal layer61E as power supplying layers, filling of the metal paste, and the like.

In the manufacturing steps described above, the metal layers61E,62E,63E,64E,65E,66E,67E are connected in series by the via wirings V1to V7in the stacked structure including the structural body41, the substrate30, and the structural bodies42to47. The series conductor of the metal layers61E,62E,63E,64E,65E,66E,67E and the via wirings V1to V7corresponds to the portion of approximately (5+½) windings of the helical coil.

In the steps illustrated inFIGS. 23A and 24B, the through holes67X,76X may be formed after stacking the structural body47on the structural body46through the adhesive layer76.

In the manufacturing steps described above, the stacked body23including the structural body41stacked on the lower surface30A of the substrate30, and the plurality of structural bodies42to47stacked in order on the upper surface30B of the substrate30may be manufactured in each individual region A1.

In the step illustrated inFIG. 26A, the reel-like substrate100having the structure illustrated inFIGS. 25A and 25Bis cut along the cutting position A2illustrated inFIG. 9to be singulated into an individual sheet-like coil substrate10. In the example ofFIG. 26A, twelve individual regions A1are formed in the coil substrate10. The substrate100completed in the steps illustrated inFIGS. 25A and 25Bmay be shipped as a product without undergoing the step illustrated inFIG. 26A.

In the steps illustrated inFIGS. 26B to 28B, the coil substrate10is shaped when punched out to remove unnecessary portions, and the metal layers61E to67E are processed into the shapes of the wirings61to67of the helical coil.FIG. 26Billustrates the metal layer67E and the adhesive layer76before shaping the coil substrate10. InFIG. 26B, the illustration of the insulation layer57is omitted, and the adhesive layer76exposed from the opening207Y and the grooves67Y,67Z is illustrated shaded.FIG. 27schematically illustrates the shapes of the metal layers61E to67E before shaping the coil substrate10. For example, the coil substrate10illustrated inFIGS. 26B and 27is shaped as illustrated inFIGS. 28A and 28Bby undergoing pressing that uses a die, for example. In the present example, the substrate30, the insulation layers51to57, the metal layers61E to67E, and the adhesive layers71to76(refer toFIG. 25B) are punched out when undergoing pressing at the position corresponding to the opening20Y to remove unnecessary portions from the coil substrate10illustrated inFIGS. 26B and 27. Furthermore, the substrate30, the insulation layers51to57, the metal layers61E to67E, and the adhesive layers71to76are punched out when undergoing pressing at the position overlapping the region illustrated by broken lines inFIGS. 26B and 27in a plan view to remove the unnecessary portion of the coil substrate10. As illustrated inFIG. 28B, this forms the opening20Y at a certain location in the block11, and the stacked body23is shaped to a substantially rectangular shape in a plan view. Furthermore, the through hole23X is formed at substantially the central part of the stacked body23, and the metal layers61E to67E are each shaped into the wirings61to67, as illustrated inFIG. 28A. The wirings61to67are connected in series by the via wirings V1to V7to be formed as a helical coil having approximately (5+½) windings. The formation of the through hole23X exposes the end face of each wiring61to67from the inner wall surface of the through hole23X. Furthermore, the formation of the opening20Y exposes the end face of each wiring61to67from the outer wall surface of the stacked body23(refer toFIG. 3). The stacked body23is formed in each individual region A1, and the adjacent stacked bodies23are coupled by the coupling portion12.

In the present embodiment, when performing pressing, the metal layer (metal layer61E to67E and metal layer61D to67D) in each structural body41to47prior to shaping have substantially the same shape. In other words, the difference in shape of the metal layer formed in each structural body41to47is reduced by arranging the metal layer61D to67D serving as the dummy pattern in each structural body41to47. This reduces deformation of the stacked body23that would be caused by a difference in the shapes of the metal layer during pressing.

The coil substrate10may be shaped (i.e., opening20Y and through hole23X may be formed) through laser processing instead of pressing that uses a die. In this step, the recognition mark12X that extends through the coupling portion12in the thickness direction may be formed at a certain location in the coupling portion12, as illustrated inFIG. 28B, when forming the opening20Y and the through hole23X. The recognition mark12X may be formed, for example, through press working using a die or through laser processing.

The steps illustrated inFIGS. 29 and 30Aform the insulation film25that covers the entire surface of the stacked body23including the inner wall surface of the through hole23X. The insulation film25continuously covers the outer wall surface of the stacked body23formed in each individual region A1, the lower surface and the side surface of the wiring61of the lowermost layer, the upper surface of the insulation layer57of the uppermost layer, the upper surfaces of the via wirings V7, V8, and the inner wall surface of the through hole23X. Therefore, the insulation film25covers the end face of each wiring61to67exposed at the outer wall surface of the stacked body23and the inner wall surface of the through hole23X. Thus, even if the encapsulation resin91of the inductor90(refer toFIG. 8B) contains the conductive body (filler of magnetic body, etc.), the insulation film25limits short-circuiting of each of the wirings61to67with the conductive body of the encapsulation resin91.

The insulation film25can be formed, for example, using the spin coating method and the spray coating method. An electrodeposited resist may be used as the insulation film25. In this case, the electrodeposited resist (insulation film25) is attached only to the end face of each wiring61to67exposed at the outer wall surface of the stacked body23and the inner wall surface of the through hole23X by performing an electrodeposition application process.

The above manufacturing steps manufacture the coil substrate20in each individual region A1and the coil substrate10including the coil substrates20.

A method for manufacturing the inductor90will now be described.

First, in the step illustrated inFIG. 30B, the encapsulation resin91is formed to encapsulate the entire coil substrate20in each individual region A1. This fills the through hole20X of the coil substrate20with the encapsulation resin91and covers the outer wall surface of the coil substrate20, the upper surface of the coil substrate20(upper surface of insulation film25), and the lower surface of the coil substrate20(lower surface of insulation film25) with the encapsulation resin91. A method for filling the encapsulation resin91includes, for example, a transfer mold method, a compression mold method, and an injection mold method.

The structure (coil substrate10) illustrated inFIG. 30Bis cut along the position of the individual region A1illustrated with a broken line. This removes the coupling portion12and the outer frame13, and the coil substrate10is singulated into the coil substrate20(refer toFIG. 31A) encapsulated by the encapsulation resin91. In this case, a plurality of coil substrates20is obtained. The connecting portion61A is exposed at one side surface20A of the coil substrate20, and the connecting portion67A is exposed at the other side surface20B of the coil substrate20.

In the steps illustrated inFIGS. 30B and 31A, the coil substrate10is cut and singulated into a plurality of coil substrates20after forming the encapsulation resin91for encapsulating the coil substrate20in each individual region A1. Instead, for example, the coil substrate10may be singulated into the coil substrates20, and then each coil substrate20may be encapsulated with the encapsulation resin91excluding the side surfaces20A,20B.

Then, in the step illustrated inFIG. 31B, the electrodes92,93are formed. The electrode92continuously covers the side surface20A of the coil substrate20and one side surface, the upper surface, and the lower surface of the encapsulation resin91. The electrode93continuously covers the side surface20B of the coil substrate20, and the other side surface, the upper surface, and the lower surface of the encapsulation resin91. The inner wall surface of the electrode92contact the side surface of the connecting portion61A exposed at the side surface20A of the coil substrate20. Therefore, the wiring61including the connecting portion61A is electrically connected to the electrode92. In the same manner, the inner wall surface of the electrode93contacts the side surface of the connecting portion67A exposed at the side surface20B of the coil substrate20. Therefore, the wiring67including the connecting portion67A is electrically connected to the electrode93.

The above manufacturing steps manufactures the inductor90illustrated inFIG. 8B.

The present embodiment has the advantages described below.

(1) The structural bodies41to47including the wirings61to67and the insulation layers51to57are stacked on the substrate3, and the wirings61to67are connected in series by the via wirings V1to V7to form a single helical coil. In such a structure, the coil of any number of windings may be formed without changing the planar shape of the coil (inductor) by adjusting the number of structural bodies stacked on the substrate30. This facilitates the formation of a coil having a smaller size (e.g., planar shape of 1.6 mm×0.8 mm) than the conventional size (e.g., planar shape of 1.6 mm×1.6 mm).

(2) The number of windings (number of turns) of the coil is increased without changing the planar shape of the coil (inductor) by increasing the number of structural bodies stacked on the substrate30. This facilitates the formation of a small coil having a large inductance.

(3) In each structural body42to47, the insulation layers52to57include the through holes52X to57X having larger planar shapes than the through holes62X to67X of the wirings62to67. Furthermore, the through holes62X,52X are filled with the via wiring V2, the through holes63X,53X are filled with the via wiring V3, the through holes64X,54X are filled with the via wiring V4, the through holes65X,55X are filled with the via wiring V5, the through holes66X,56X are filled with the via wiring V6, and the through holes67X,57X are filled with the via wiring V7. The via wirings V2to V7are connected to the inner side surfaces of the through holes62X to67X, and connected to the upper surfaces of the wirings62to67exposed from the through holes52X to57X around the through holes62X to67X. In this structure, the contact area of the via wirings V2to V7and the wirings62to67is increased compared to when the through holes52X to57X have planar shapes with the same size as the through holes62X to67X. As a result, the connection reliability between the via wirings V2to V7and the wirings62to67is enhanced. Furthermore, the connection reliability of the wirings62to67is enhanced.

(4) When stacking the structural body43on the structural body42, the structural body43including the metal layer63E with the through hole63X and the insulation layer53is stacked on the lower surface103A of the support film103, and the adhesive layer72including the through hole72X that communicates with the through hole63X is stacked on the structural body43. The insulation layer52of the structural body42includes the through hole52Y having a larger planar shape than the through holes63X,72X. The structural body43is stacked on the structural body42by way of the adhesive layer72with the support film103arranged on the outer side. This limits leakage of the adhesive layer72into the through hole72X since the through hole52Y has a larger planar shape than the through hole72X. Therefore, even if a high pressure is applied to the structural bodies42,43and the adhesive layer72or a material of high fluidity is used as the material of the adhesive layer72when stacking the structural body43on the structural body42by way of the adhesive layer72, reduction in the size of the planar shape of the through hole72X is limited. The same applied when stacking the other structural bodies44to47.

(5) The through electrodes (via wirings V2to V8) that electrically connect the wiring62to67extend through the insulation layer of the structural body at the lower side of the two adjacent structural bodies and the wiring and the insulation layer of the structural body at the upper side. Thus, the insulation layers52to57of the structural bodies42to47each include two through electrodes. In the present example, the via wirings V2, V3are formed in the insulation layer52, the via wirings V3, V4are formed in the insulation layer53, the via wirings V4, V5are formed in the insulation layer54, the via wirings V5, V6are formed in the insulation layer55, the via wirings V6, V7are formed in the insulation layer56, and the via wirings V7, V8are formed in the insulation layer57. In such a structure, the via wirings V2to V8function as support bodies and maintain the rigidity of the insulation layers52to57. This limits twisting of the inductor90.

(6) The substrate30having a lower thermal expansion coefficient than the insulation layers51to57of the structural bodies41to47is arranged in the stacked body23. The thermal deformation (thermal contraction or thermal expansion) of the substrate30is thus small when a temperature change occurs in the coil substrate20. Therefore, displacement of the wirings61to67is limited. In other words, deviation in the position of the coil (coil substrate20) formed by the wirings61to67from the designed position is limited even if a temperature change occurs in the coil substrate20. This improves the position accuracy of the coil formed by the wirings61to67.

(7) The rigidity of the substrate30is higher than the insulation layers51to57. For example, the substrate30is thicker than the insulation layers51to57. Thermal deformation of the entire coil substrate20is limited by providing the substrate30with high rigidity.

(8) The structural bodies41to47are stacked on the substrate30to form the stacked body23, and the wiring61is arranged on the lowermost layer of the stacked body23. The wiring61(e.g., copper layer) has a higher adhesiveness to the insulation film25than the substrate30(e.g., polyimide film). Thus, the adhesiveness of the stacked body23and the insulation film25is increased compared to when the substrate30is arranged on the lowermost layer of the stacked body23. If the substrate30is arranged on the lowermost layer of the stacked body23, surface treatment (e.g., plasma process) needs to be performed on the lower surface of the substrate30before forming the insulation film25to increase the adhesiveness of the substrate30and the insulation film25. In the present example, such surface treatment does not need to be performed since the adhesiveness of the wiring61and the insulation film25is high.

(9) In the coil substrate10, the stacked body23and the outer frame13share the substrate30, and the sprocket holes13X are formed in the outer frame13. Thus, the coil substrate10is easily conveyed using the sprocket holes13X of the substrate30without using an additional member.

(10) Instead of the manufacturing method of the present embodiment, the wiring corresponding to the shape of the coil may be formed in each structural body before stacking the plurality of structural bodies. For example, the wirings61to67(with the through hole23X) illustrated inFIG. 7are formed in the structural bodies41to47. Then, the structural bodies41to47are stacked on the substrate30to form the stacked body23. In this method, however, the wirings61to67may be displaced in the planar direction (e.g., laterally), and the stacked wirings61to67may not completely overlap in a plan view. When the through hole and the like are formed in the stacked body, the displaced wirings may be partially removed. Such a problem is solved by narrowing the wiring to form in each structural body in advance, for example. However, this would increase the DC resistance of the coil.

To cope with such a problem, in the manufacturing method of the present embodiment, the metal layers61E to67E having larger planar shapes than the wiring61to67, which have the shapes of a helical coil, are formed in each structural body41to47in advance. The structural bodies41to47are then stacked on the substrate30to form the stacked body23. The stacked body23is shaped in the thickness direction, and the metal layers61E to67E are processed so that the wirings61to67are shaped into a helical coil. Thus, the wirings61to67that overlap each other in a plan view are stacked with high accuracy without being displaced in the planar direction. Therefore, the helical coil is accurately formed. As a result, the DC resistance of the helical coil becomes small. In other words, displacement of the wirings61to67in the planar direction does not need to be taken into consideration. Thus, each wiring61to67may be widened, and the DC resistance of the coil may be decreased.

(11) A reel-like (tape-like) flexible insulative resin film is used as the substrate100and the support films102to107. This allows the coil substrate10to be manufactured reel-to-reel. Therefore, the cost of the coil substrate10may be decreased when mass-produced.

(12) The number of windings of each of the wirings61to67is less than or equal to a single winding of the coil. This allows wider wirings to be formed in a single structural body. In other words, the cross-sectional area in the widthwise direction of each wiring61to67may be increased, and the winding wiring resistance related with the inductor performance may be decreased.

(13) The metal layers61D to67D serving as dummy patterns are arranged in each structural body41to47. Thus, the difference in the shape of the metal layer becomes small in the structural bodies41to47. This limits the formation of valleys and ridges in the insulation layers51to57covering the metal layers that would be caused by differences in the shape of the metal layer.

(14) The metal layers81to87are stacked on the substrate30where the coupling portion12is located. This increases the mechanical strength of the entire coil substrate10.

Modified Examples of First Embodiment

The first embodiment may be modified to the forms described below.

In the manufacturing steps of the first embodiment, the formation of the openings201Y to207Y may be omitted. In this case, for example, only the grooves61Y,61Z are formed in the metal foil161covering the entire lower surface of the insulation layer51in the step of patterning the metal foil161illustrated inFIG. 11B. In other words, the metal foil161(metal layer61E) that covers the lower surface of the insulation layer51is formed excluding the grooves61Y,61Z. This is the same for the other layers. For example, the metal layer62E that covers the lower surface of the insulation layer52is formed on the lower surface of the insulation layer52excluding the grooves62Y,62Z.

In the first embodiment and the modification described above, a recognition mark similar to the recognition mark12X may be formed in the outer frame13. In other words, a through hole for positioning may be formed in the outer frame13. In this case, the recognition mark and the sprocket hole13X may both be formed in the outer frame13. Alternatively, only the recognition mark may be formed in the outer frame13.

In the first embodiment, the via wiring V1filling the through hole51X of the insulation layer51and a portion of the through hole30X of the substrate30is formed. Then, the structural body42is stacked on the upper surface30B of the substrate30by way of the adhesive layer71. Subsequently, the via wiring V2for filling the through holes71X,62X,52X is formed on the via wiring V1. Instead, the formation of the via wiring V1may be omitted. In this case, the structural body42is stacked on the upper surface30B of the substrate through the adhesive layer71. Then, the via wiring V2may be formed in the through holes51X,30X,71X,62X, and52X.

In the first embodiment and each modification described above, the through holes52Y to56Y of the insulation layers52to56have larger planar shapes than the through holes72X to76X of the adhesive layers72to76immediately above the insulation layers52to56. Instead, for example, as illustrated inFIG. 32, the planar shapes of the through holes52Y to56Y (only through holes52Y,55Y,56Y illustrated inFIG. 32) may be substantially the same size as the through holes72X to76X (through holes72X,75X,76X inFIG. 32) of the adhesive layers72to76. Such a structure also has advantages (1) to (3) and (5) to (14) of the embodiment described above.

In the first embodiment and each modification described above, the through hole30X of the substrate30and the through hole51X of the insulation layer51have larger planar shapes than the through hole71X of the adhesive layer71stacked on the substrate30. Instead, for example, as illustrated inFIG. 32, the planar shapes of the through holes30X,51X may be substantially the same size as the through hole71X. In this case, for example, the through holes51X,30X may be filled with the via wiring V1. Alternatively, the via wiring V1may be omitted, and the through holes51X,30X,71X,62X, and52X may be filled with the via wiring V2.

In the first embodiment and each modification described above, the number of structural bodies stacked on the substrate30is not particularly limited. For example, two or more structural bodies may be stacked on the lower surface30A of the substrate30, or one to five or seven or more structural bodies may be stacked on the upper surface30B of the substrate30. Furthermore, the number of structural bodies stacked on the lower surface30A of the substrate30and the number of structural bodies stacked on the upper surface30B of the substrate30may be adjusted so that the substrate30is arranged near the center in the thickness direction of the stacked body23.

In the first embodiment and each modification described above, the substrate30may be omitted. For example, as illustrated inFIG. 33, the stacked body23A of the inductor90A does not include the structure corresponding to the substrate30. InFIG. 33, the structural body42is stacked on the insulation layer51of the structural body41by way of the adhesive layer71. In this case, the wiring61and the wiring62are electrically connected by the via wiring V2in the through holes71X,62X,52X. The inter-layer distance between the wirings61,62can be shortened by omitting the substrate30to increase the inductance of the inductor90A. The entire inductor90can be reduced in thickness by omitting the substrate30. fill

Second Embodiment

A second embodiment will now be described with reference toFIGS. 34 to 38.

In a stacked body23B of an inductor90B illustrated inFIG. 34, the structural body41(insulation layer51and wiring61), the substrate30, and the via wiring V1are omitted from the inductor90illustrated inFIG. 8B, and the structural body42is stacked on the adhesive layer71. Thus, in the stacked body23B, the lower surface of the adhesive layer71is the outermost surface (lowermost surface herein) of the stacked body23B. In this case, for example, the through holes71X,62X,52X are filled with the via wiring V2, and the lower end face of the via wiring V2is exposed from the adhesive layer71. The insulation film25is formed to cover the lower end face of the via wiring V2and the lower surface of the adhesive layer71. In the stacked body23B, the wiring62is the lowermost wiring. Thus, the connecting portion62A is formed at one end of the wiring62in place of the connecting portion61A.

One example of a method for manufacturing the inductor90B will now be described.

First, in the step illustrated inFIG. 35A, the insulation layer52including the through holes52X,52Y is stacked on the lower surface102A of the support film102, and the metal foil including the metal layers62D,62E,82and the connecting portion62A is stacked on the insulation layer52like the steps illustrated inFIGS. 12A and 12B. Then, the adhesive layer71is arranged on the lower side of the metal layers62D,62E,82.

In the step illustrated inFIG. 35B, the adhesive layer71in the semi-cured state that covers the metal layers62D,62E,82and the entire surface of the connecting portion62A is stacked on the lower surface of the insulation layer52like the step illustrated inFIG. 13A. Then, the through hole62X, which extends through the metal layer62E exposed from the through hole52X, and the through hole71X, which extends through the adhesive layer71and communicates with the through hole62X, are formed like the step illustrated inFIG. 13B.

In the step illustrated inFIG. 35C, the structural body42is stacked on the upper surface110A of the support substrate110by way of the adhesive layer71. The structure illustrated inFIG. 35Cis heated and pressurized from above and below through vacuum pressing, for example. Then, the adhesive layer71is cured. This adheres the adhesive layer71to the support substrate110, and the adhesive layer71is adhered to the structural body42. In this case, a portion of the upper surface110A of the support substrate110is exposed from the through hole71X. The metal plate and the metal foil, for example, may be used as the support substrate110. A tape-like substrate of resin film such as polyimide film, PPS (polyphenylene sulfide) film, a glass plate, and the like may be used as the support substrate110. In the present embodiment, a copper plate is used for the support substrate110. The support substrate110is formed, for example, to be thicker than the wiring62and thicker than the insulation layer52. The mechanical strength of the structural body42in the middle of manufacturing can be sufficiently ensured by using such support substrate110. This limits degradation in the handling property of the structural body42during manufacturing even if the substrate30is omitted.

In the step illustrated inFIG. 36A, the via wiring V2is formed on the upper surface110A of the support substrate110exposed from the through hole71X. The through holes71X,62X,52X are filled with the via wiring V2. The via wiring V2may be formed, for example, by performing electrolytic plating. For example, a first conductive layer (e.g., Ni layer) is formed on the support substrate110exposed from the through hole71X through electrolytic plating that uses the support substrate110(copper plate herein) as the power supplying layer. Then, a second conductive layer (e.g., Cu layer) is formed on the first conductive layer through electrolytic plating. This forms the via wiring V2having a two-layer structure. A material that functions as an etching stopper layer when removing the support substrate110through etching in a subsequent step is preferred as the material of the first conductive layer. Thus, the support substrate110functions as a supporting body in the manufacturing process and also functions as the power supplying layer in the electrolytic plating. The via wiring V2can also be formed through other processes such as by filling a metal paste or the like.

In the step illustrated inFIG. 36B, the structural bodies43to47are stacked on the structural body42, which is stacked on the upper surface110A of the support substrate110, like the steps illustrated inFIGS. 15A to 25B. In the manufacturing steps described above, the stacked body23B including the plurality of structural bodies42to47stacked in order on the upper surface110A of the support substrate110in each individual region A1can be manufactured. When forming the via wirings V3to V7through electrolytic plating, the support substrate110and the via wiring V2may be used as power supplying layers.

In the step illustrated inFIG. 37A, the metal layers62E to67E (refer toFIG. 36B) are shaped when punched out and processed to have the shapes of the wirings62to67of the helical coil like the steps illustrated inFIGS. 26A to 28B. In this step, the metal layers62E to67E are shaped with the stacked body23B stacked on the support substrate110, which has high rigidity. This limits displacement of the wirings62to67when shaped. The position accuracy of the wirings62to67may thus be improved. The wirings62to67improve the position accuracy of the coil.

The support substrate110used as a temporary substrate is then removed. For example, if the copper plate is used for the support substrate110, the via wiring V2(specifically, first conductive layer, which is Ni layer) and the adhesive layer71are selectively etched by wet etching using aqueous ferric chloride, aqueous copper chloride, ammonium persulfate aqueous solution, or the like. This removes the support substrate110. In this case, the first conductive layer (Ni layer) of the via wiring V2and the adhesive layer71function as the etching stopper layers for when etching the support substrate110. If the PI film, and the like are used for the support substrate110or if a stripping layer is arranged, the support substrate110may be mechanically removed from the stacked body23B. As illustrated inFIG. 37B, the removal of the support substrate110exposes the lower end face of the via wiring V2and the lower surface of the adhesive layer71to the outer side.

In this manner, the support substrate110is relatively thick to ensure the mechanical strength of the structural bodies42to47and the adhesive layers71to76in the manufacturing process, and the support substrate110is removed after stacking the structural bodies42to47. Thus, each member of the stacked body23B does not need to be thick. Therefore, the entire stacked body23B can be thinned.

Then, in the step illustrated inFIG. 38, the insulation film25that covers the entire surface of the stacked body23B including the inner wall surface of the through hole23X is formed. This manufactures the coil substrate20in each individual region A1. Then, the inductor90B illustrated inFIG. 34can be manufactured by performing steps similar to the steps illustrated inFIGS. 30B to 31B.

The inductance of the inductor90B may be improved by omitting the structural body41(insulation layer51and wiring61), the substrate30, and the via wiring V1.

Third Embodiment

A third embodiment will now be described with reference toFIGS. 39 to 45B.

In a stacked body23C of an inductor90C illustrated inFIG. 39, the substrate30is omitted from the inductor90illustrated inFIG. 8B, and the structural body42is stacked on the insulation layer51of the structural body41with the adhesive layer71located in between. More specifically, the insulation layer51, which includes the through hole51X, is stacked on the upper surface of the wiring61, which is the lowermost layer, and the adhesive layer71is stacked on the upper surface of the insulation layer51. The adhesive layer71is partially located in the through hole51X and covers the wall surface of the through hole51X. Further, the adhesive layer71covers portions of the side surfaces of the wiring62and the metal layer62D. The adhesive layer71includes the through hole71X that extends through the adhesive layer71in the thickness direction of the adhesive layer71. The upper surface of the wiring61is partially exposed through the through hole71X. The through hole71X extends from the upper surface of the adhesive layer71to the lower surface of the adhesive layer71formed in the through hole51X. That is, the through hole71X is partially formed in the through hole51X. In other words, the through hole51X has a larger planar shape than the through hole71X.

The wiring62is stacked on the upper surface of the adhesive layer71. The wiring62includes the through hole62X, which is in communication with the through hole71X. The insulation layer52is stacked on the upper surface of the wiring62and the upper surface of the adhesive layer71. The insulation layer52includes the through hole52X, which extends through the insulation layer52in the thickness direction and is in communication with the through holes62X and71X. The upper surface of the wiring62around the through hole62X is exposed from the through hole52X. Accordingly, the through hole52X has a larger planar shape than the through holes62X and71X.

The via wiring V2is formed in the through holes52X,62X, and71X, which are in communication with one another. The via wiring V2is formed on the wiring61, which is exposed from the through hole71X. The through holes52X,62X, and71X are all filled with the via wiring V2. The via wiring V2functions as a through electrode that connects the wiring61and the wiring62in series.

In the coil substrate20illustrated inFIG. 39, insulation films25C that partially cover the surface of the stacked body23C are formed in place of the insulation film25that covers the entire surface of the stacked body23illustrated inFIG. 8B. Each insulation film25C covers the surface of a conductor exposed from the surface of the stacked body23C. In the present example, the insulation films25C cover the side surfaces of the wirings62to67that are exposed from the wall surface of the through hole23X, the side surfaces of the wirings62to67exposed from the outer walls surface of the stacked body23C, the side surfaces and lower surface of the wiring61in the lowermost layer, and the upper surfaces of the via wirings V7and V8(only via wiring V7illustrated inFIG. 39) in the uppermost layer. In this manner, the insulation films25C, which cover the wirings61to67and the via wirings V7and V8, are discrete or spaced apart from one another. For example, the insulation film25C that covers the side surfaces and the lower surface of the wiring61is discrete and spaced apart from the insulation film25C that covers the side surface of the wiring62exposed from the wall surface of the through hole23X. The insulation films25C are formed from an electrodeposition resin, which is obtained through electrodeposition (electrodeposition coating). The material of the electrodeposition resin may be an insulative resin, such as an epoxy resin, an acrylic resin, or an imide resin. The insulation films25C may also partially cover the insulation layers51to57and the adhesive layers71to76that are formed around the wirings61to67and the via wirings V7and V8.

The surfaces of the connecting portions61A and67A, which are exposed through the side surfaces20A and20B of the stacked body23C, are exposed from the insulation films25C and thus not covered by the insulation films25C.

In the same manner as the first and second embodiments, a magnetic material, which is formed from magnetic powder and a resin that serves as a bonding material, is used for the encapsulation resin91. Thus, the encapsulation resin91functions as a magnetic body. For example, ferrite or a magnetic metal, such as iron or an iron-based alloy, may be used as the material of the magnetic powder. As the material of the bonding material, for example, a thermosetting resin such as an epoxy-based resin or a thermoplastic resin may be used.

The encapsulation resin91entirely covers the coil substrate20(stacked body23C and insulation films25C) excluding the side surfaces20A and20B where the connecting portions61A and67A are exposed. Accordingly, the gaps between the insulation films25C are filled with the encapsulation resin91. In other words, the encapsulation resin91contacts and directly covers portions of the surfaces of the insulation layers51to57and portions of the surfaces of the adhesive layers71to76. This increases the volume of the encapsulation resin91, which functions as the magnetic body, in, for example, the through hole23X and increases the inductance of the inductor90C. Further, the omission of the substrate30allows the inductor90C to be entirely reduced in thickness.

In the third embodiment, the through hole23X is one example of a first through hole, the through hole52Y is one example of a second through hole, the through hole72X is one example of a third through hole, the through hole63X is one example of a fourth through hole, the through hole53X is one example of a fifth through hole, the through hole62X is one example of a sixth through hole, the through hole52X is one example of a seventh through hole, the through hole71X is one example of an eighth through hole, and the through hole51X is one example of an ninth through hole. The wiring62is one example of a first wiring, the wiring63is one example of a second wiring, the wiring61is one example of a third wiring, the insulation layer52is one example of a first insulation layer, the insulation layer53is one example of a second insulation layer, and the insulation layer51is one example of a third insulation layer. The adhesive layer72is one example of a first adhesive layer, the adhesive layer71is one example of a second adhesive layer, the via wirings V2to V8are each one example of a through electrode, the via wiring V3is one example of a first through electrode, and the via wiring V2is one example of a second through electrode. The insulation films25C are each one example of a discrete insulation film. The insulation films25C that cover the surfaces of the wirings61to67exposed from the surface of the stacked body23correspond to first discrete insulation films. The insulation films25C that cover the surfaces of the via wirings V7and V8exposed from the surface of the stacked body23correspond to second discrete insulation films.

One example of a method for manufacturing the inductor90C will now be described.

In the step illustrated inFIGS. 40A to 40C, a support film101having a structure similar to the substrate100illustrated inFIG. 9is first prepared. As illustrated inFIGS. 40A and 40C, the support film101includes a block11with a plurality of individual regions A1(only one illustrated inFIGS. 40A to 40C) and an outer frame13projecting out of the block11. A reel-like (tape-like) flexible insulative resin film may be used, for example, for the support film101. For example, polyphenylene sulfide, polyimide film, and polyethylene naphtalate film may be used as the support film101. The thickness of the support film101is, for example, approximately 12 to 50 μm.

Then, in the same manner as the step illustrated inFIG. 10A, the insulation layer51is stacked, in a semi-cured state, on a lower surface101A of the support film101in a region excluding the outer frame13(i.e., in block11). As illustrated inFIGS. 40A and 40B, a pressing process or a laser cutting process is performed to form the through hole51X that extends through the support film101and the insulation layer51in the thickness direction. At the same time as when the through hole51X is formed or before stacking the insulation layer51, sprocket holes101X are formed in the outer frame13of the support film101.

In the step illustrated inFIG. 41A, the metal foil161is stacked on the lower surface of the semi-cured insulation layer51. The metal foil161covers, for example, the entire lower surface of the insulation layer51. For example, the metal foil161is laminated onto the lower surface of the semi-cured insulation layer51by thermal compression bonding. Then, a thermal curing process is performed under a temperature of approximately 150° C. to cure the semi-cured insulation layer51.

In the same manner as the step illustrated inFIGS. 11B and 11C, the metal foil161is patterned using a wiring formation process such as a subtractive process. More specifically, as illustrated inFIGS. 41B and 41C, the metal foil161is patterned to form the metal layer61E on the lower surface of the insulation layer51in the individual region A1. The patterning of the metal foil161forms the connecting portion61A at one end of the metal layer61E and forms the metal layer61D, which serves as a dummy pattern. As a result, the structural body41that includes the insulation layer51, the metal layer61E, and the connecting portion61A is stacked on the lower surface101A of the support film101. Further, in this step, as illustrated inFIG. 410, the metal layer81, which is connected to the connecting portion61A and the metal layer61D, is formed on the lower surface of the insulation layer51at the location of the connecting portion12. In other words, in this step, the metal foil161illustrated inFIG. 41Ais patterned to form the opening201Y and the grooves61Y and61Z. InFIG. 41C, the insulation layer51exposed from the opening201Y and the grooves61Y and61Z is shaded.

In the step illustrated inFIG. 42A, the support film101illustrated inFIG. 41Bis removed from the insulation layer51. For example, the support film101is mechanically removed from the insulation layer51.

In the step illustrated inFIG. 42B, the insulation layer52, which includes the through holes52X and52Y, is stacked on the lower surface102A of the support film102and a metal foil, which includes the metal layers62D,62E, and82, is stacked on the insulation layer52in the same manner as the step illustrated inFIG. 12B. Then, the semi-cured adhesive layer71, which covers the entire surfaces of the metal layers62D,62E, and82, is stacked on the lower surface of the insulation layer52in the same manner as the step illustrated inFIG. 13A.

In the step illustrated inFIG. 42C, the through hole62X, which extends through the metal layer62E that is exposed from the through hole52X, and the through hole71X, which extends through the adhesive layer71and is in communication with the through hole62X, are formed in the same manner as the step illustrated inFIG. 13B.

In the step illustrated inFIG. 42D, the structural body42and the support film102are stacked, with the adhesive layer71located in between, on the upper surface of the insulation layer51of the structural body41so that the structural body41and the support film102are arranged at the outer side. For example, the structure illustrated inFIG. 42Dis heated and pressurized from above and below through vacuum pressing. As a result, the semi-cured adhesive layer71is pressed and spread in the planar direction by the lower surface of the metal layer62E and the upper surface of the insulation layer51. This spreads a portion of the adhesive layer71in the through hole51X, and the spread adhesive layer71covers the wall surface of the through hole51x. Consequently, the through hole71X is partially formed in the through hole51X.

Then, the adhesive layer71is cured. This keeps the through hole71X, the through hole62X, and the through hole52X in communication with one another. Thus, the upper surface of the metal layer61E is partially exposed from the through hole71X. Then, the support film102is removed from the insulation layer52.

In the step illustrated inFIG. 43A, the via wiring V2is formed on the upper surface of the metal layer61E exposed from the through hole71X. The through holes71x,62X, and52X are filled with the via wiring V2. As a result, the via wiring V2connects the metal layer61E and the wiring layer623in series. The via wiring V2may be formed, for example, by performing electrolytic plating that uses both of the metal layer81and the metal layer61E as the power supplying layers or by filling metal paste or the like.

In the manufacturing steps described above, the metal layer61E is connected in series to the metal layer62E by the via wiring V2in the stacked structure that includes the structural body41and the structural body42.

In the step illustrated inFIG. 43B, the structural bodies43to47are stacked on the structural body42in the same manner as the steps illustrated inFIGS. 15A to 25B. This manufactures the stacked body23C, which includes the sequentially stacked structural bodies41to47, in each individual region A1.

In the step illustrated inFIGS. 44A and 44B, the stacked body23C is molded in the same manner as the steps illustrated inFIGS. 26A to 28B, and the metal layers61E to67E (refer toFIG. 43B) are shaped when punched out and processed to have the shapes of the wirings61to67of the helical coil. As a result, the through hole23X is formed in the central portion of the stacked body23C, as illustrated inFIG. 44A. The formation of the through hole23X exposes the end surface of each of the wirings61to67from the wall surface of the through hole23X. Further, in this step, as illustrated inFIG. 44B, the opening20Y is formed at a predetermined location in each individual region A1, and the stacked body23C is molded to be rectangular in a plan view. The formation of the opening20Y exposes the end surface of each of the wirings61to67from the outer wall surface (side wall) of the stacked body23C.FIG. 44Bis a cross-sectional view of the coil substrate20taken along line44b-44binFIG. 41C.

When the stacked body23C is punched in a pressing (stamping) process to form the through hole23X and the opening20Y, burrs may be produced at the end surfaces of the wirings61to67exposed from the wall surface of the through hole23X and the end surfaces of the wirings61to67exposed from the outer wall surface of the stacked body23C (wall surface of the opening20Y). To remove such burrs, a burr removal step may be performed. For example, an etching process such as wet etching may be performed to remove the burrs from the end surfaces of the wirings61to67. The burr removal step facilitates the covering of the end surfaces of the wirings61to67with the insulation films25C in a subsequent step.

Further, in the burr removal step, the etching process (wet etching) may be performed so that the end surfaces of the wirings61to67are located inward to the stacked body23C from the wall surface of the through hole23X to form recesses in the wall surface of the through hole23X at the location of the end surfaces of the wirings61to67. In this case, in a subsequent step, the insulation films25C are formed to fill the recesses. This reduces portions of the insulation films25C protruding from the wall surface of the through hole23X toward the through hole23X. In other words, the surfaces of the insulation films25C are substantially flush with the end surfaces of the insulation layers51to57and the end surfaces of the adhesive layers71to76on the wall surface of the through hole23X. This facilitates the filling of the magnetic material (encapsulation resin91) in a subsequent step and increases the volume (filling amount) of the magnetic material (encapsulation resin91) to increase the inductance of the inductor90C. In the same manner, recesses may be formed in the outer wall surface of the stacked body23C (wall surface of the opening20Y) at the location of the end surfaces of the wirings61to67.

In the step illustrated inFIGS. 45A and 45B, electrodeposition is performed to form the insulation films25C that cover the surfaces of the wirings61to67and the via wirings V7and V8that are exposed from the surface of the stacked body23C. More specifically, the insulation films25C cover the side surfaces (end surfaces) of the wirings62to67that are exposed from the inner wall surface of the through hole23X, the side surfaces (end surfaces) of the wirings62to67that are exposed from the outer wall surface of the stacked body23C, the side surfaces and the lower surface of the wiring61, and the upper surfaces of the via wirings V7and V8. The formation of the insulation films25C through electrodeposition allows the thickness of the insulation films25C to be easily controlled. That is, the insulation films25cmay be minimized in thickness. Further, electrodeposition selectively (partially) arranges the insulation films25C on the surface of the stacked body23C to cover the wirings61to67and the via wirings V7and V8with high accuracy. As a result, the region in which the insulation films25C are formed may be minimized, and the formation of voids in each insulation film25C may be limited.FIG. 45Bis a cross-sectional view of the coil substrate20taken along line44b-44binFIG. 41C.

Then, steps that are the same as the steps30B to31B are performed to manufacture the inductor90C illustrated inFIG. 39. In the third embodiment, the insulation films25C are thin. Thus, the encapsulation resin91may be formed near the wirings61to67, and the volume of the encapsulation resin91may be increased. This allows the inductance of the inductor90C to be increased.

Modified Examples of Third Embodiment

In the inductor90C of the third embodiment, the insulation film25of the inductor90A illustrated inFIG. 33is replaced by the insulation films25C. The inductor90(FIG. 8B) and the inductor90B (FIG. 34) may undergo the same modification.

For example, as illustrated inFIG. 46, the insulation film25of the inductor90illustrated inFIG. 8Bmay be replaced by the insulation films25C that cover the surfaces of the wirings61to67and the surfaces of the conductors, such as the via wiring V7, exposed from the surface of the stacked body23.

In the same manner, as illustrated inFIG. 47, the insulation film25of the inductor90B illustrated inFIG. 34may be replaced by the insulation films25C that cover the surfaces of the wirings62to67and the surfaces of the conductors, such as the via wirings V2and V7, exposed from the surface of the stacked body23B. In this case, the lower surface of the via wiring V2is covered by the insulation film25C.

Although not illustrated in the drawings, the insulation film25of the inductor90illustrated inFIG. 32may also be replaced by the insulation films25C.

Fourth Embodiment

A fourth embodiment will now be described with reference toFIGS. 48 to 51B.

In a stacked body23D illustrated inFIGS. 48 and 49, each of the via wirings V2to V7(only via wirings V2, V3, V6, and V7illustrated inFIG. 48) is partially exposed from the wall surface of the through hole23X. As illustrated inFIG. 49, in the present example, the through hole23X of the stacked body23D has a larger planar shape than the through hole23X of the stacked body23illustrated inFIG. 2. In the example illustrated inFIG. 49, the through hole23X eliminates a portion corresponding to approximately one-fourth of each of the via wirings V2to V8, which are generally circular in a plan view. That is, the through hole23X cuts away a portion of each of the via wirings V2to V8in the stacking direction. This exposes the cut surface (end surface) of each of the via wirings V2to V8from the wall surface of the through hole23X. For example, in the via wiring V2, as illustrated inFIG. 48, the cut surface (end surface) of each of the via wiring V2, which extends through the insulation layers51and52, the wiring62, and the adhesive layer71in the thickness direction, is exposed from the wall surface of the through hole23X. That is, the cut surface (end surface) of the via wiring V2from the upper surface of the wiring61to the lower surface of the adhesive layer72is exposed from the wall surface of the through hole23X. In other words, the through holes51X,52X,62X, and71X are in communication with the through hole23X. The wiring61is located immediately below the via wiring V2exposed from the wall surface of the through hole23X. That is, the end surface of the via wiring V2and the end surface of the wiring61immediately below the via wiring V2are continuously exposed in the stacking direction from the wall surface of the through hole23X. In the same manner as the via wiring V2and the wiring61, the via wirings V3to V8and the wirings62to67are also exposed from the wall surface of the through hole23X.

The coil substrate20of the present example includes insulation films25D that cover the surface of conductors exposed from the stacked body23D. The insulation films25D cover the end surfaces of the wirings62to67and the end surfaces of the via wirings V2to V8that are exposed from the wall surface of the through hole23X, the end surfaces of the wirings62to67exposed from the outer wall surface of the stacked body23D, the lower surface and the side surfaces of the wiring61in the lowermost layer, and the via wirings V7and V8in the uppermost layer (only via wiring V7illustrated inFIG. 48). The insulation films25D, which cover the wirings61to67and the via wirings V2to V8, are spaced apart from one another. However, some of the insulation films25D continuously cover the wirings61to67and the via wirings V2to V8that are continuously exposed from the wall surface of the through hole23X. The insulation films25D are formed from, for example, an electrodeposition resin, which is obtained through electrodeposition (electrodeposition coating). In the fourth embodiment, the insulation films25D that cover the surfaces of the wirings61to67exposed from the surface of the stacked body23D each correspond to first discrete insulation films. The insulation films25D that cover the surfaces of the via wirings V2to V8exposed from the stacked body23D correspond to second discrete insulation films.

In the inductor90D, which includes the stacked body23D, the through hole23X has a large planar shape. Thus, the encapsulation resin91formed in the through hole23X may be increased in volume. This allows the volume of the encapsulation resin91, which functions as the magnetic body, to be increased and thus allows the inductance of the inductor90D to be increased.

One example of a method for manufacturing the inductor90D will now be described.

In the step illustrated inFIG. 50A, the structural bodies41to47are sequentially stacked in the same manner as the steps illustrated inFIGS. 40A to 43Bto manufacture the stacked body23D.

In the step illustrated inFIG. 50B, the stacked body23D is molded in the same manner as the steps illustrated inFIGS. 26A to 28B, and the metal layers61E to67E (refer toFIG. 50A) are processed into wirings61to67to form a helical coil. As a result, the through hole23X is formed in the central portion of the stacked body23D at a location partially overlapping each of the via wirings V2to V8(only via wirings V2, V3, V6, and V7illustrated inFIG. 50B). The formation of the through hole23X exposes the end surface of each of the wirings61to67and the end surface of each of the via wirings V2to V8from the wall surface of the through hole23X. That is, each of the via wirings V2to V8is partially cut away in the stacking direction by the through hole23X, and the cut surface of each of the via wirings V2to V8is exposed from the wall surface of the through hole23X. In this step, as illustrated inFIG. 51A, each individual region A1includes the opening20Y at a certain location, and the stacked body23D is formed to be rectangular in a plan view. The formation of the opening20Y exposes the end surface of each of the wirings61to67(only wiring67illustrated inFIG. 51A) from the outer wall surface of the stacked body23D.

Then, in the step illustrated inFIG. 51B, electrodeposition is performed to form the insulation films25D that cover the surfaces of the conductors exposed from the surface of the stacked body23D. More specifically, the insulation films25D cover the end surfaces of the wirings62to67and the end surfaces of the via wirings V2to V8exposed from the wall surface of the through hole23X, the end surfaces of the wirings62to67exposed from the outer wall surface of the stacked body23D, the lower surface and side surfaces of the wiring61, and the upper surfaces of the via wirings V7and V8(only via wiring V7illustrated inFIG. 51B). The thickness of the insulation films25D may be easily controlled by forming the insulation films25D through electrodeposition. Further, the formation of voids in the insulation films25D may be limited by performing electrodeposition.FIG. 51Bis a cross-sectional view of the coil substrate20taken along line51b-51binFIG. 51A.

Subsequently, steps that are the same as the steps illustrated inFIGS. 30B to 31Bare performed to manufacture the inductor90D illustrated inFIG. 48.

Modified Examples of Fourth Embodiment

In the inductor90D of the fourth embodiment (FIG. 48), the formation of the through hole23X, which has a larger planar shape than the inductor900illustrated inFIG. 39, partially exposes each of the via wirings V2to V8from the wall surface of the through hole23X. The same modification may be applied to the inductor90(FIG. 8B) and the inductor90B (FIG. 34).

For example, as illustrated inFIG. 52, each of the via wirings V1to V8(only via wirings V1to V3, V6, and V7are illustrated inFIG. 52) in the inductor90ofFIG. 46may be partially exposed from the wall surface of the through hole23X.

Further, as illustrated inFIG. 53, each of the via wirings V2to V8(only via wirings V2, V3, V6, and V7are illustrated inFIG. 53) in the inductor90B ofFIG. 47may be partially exposed from the wall surface of the through hole23X.

In the inductors90D,90, and90B illustrated inFIGS. 48, 52, and 53, the opening20Y may be formed at a location partially overlapping the via wirings V1to V8in a plan view. That is, in the inductors90D,90, and90B illustrated inFIGS. 48, 52, and 53, the cut surface (end surfaces) of each of the via wirings V1to V8may be exposed from the outer wall surfaces of the stacked bodies23D,23, and23B. For example, in the inductor90D illustrated inFIG. 48, the planar shape (profile in a plan view) of the stacked body23D illustrated inFIG. 49may be reduced in size so that the end surfaces of the wirings61to67and the end surfaces of the via wirings V1to V8(through electrodes) are exposed from the outer wall surface of the stacked body23D. In this case, the insulation films25D may be partially arranged on the outer wall surface of the stacked body23D to cover the end surfaces of the wirings61to67and the end surfaces of the via wirings V1to V8that are exposed from the outer wall surface of the stacked body23D. This structure allows for further reduction in the size of the inductors90D,90, and90B.

In the inductors90D,90, and90B illustrated inFIGS. 48, 52, and 53, the insulation films25D (discrete insulation films) may be replaced by the insulation film25that entirely covers the surface of each of the stacked bodies23D,23, and23B.

In each embodiment and each modification described above, the metal layers81to87may be omitted.

In each embodiment and each modification described above, the metal layers61D to67D (dummy patterns) may be omitted.

In the first and second embodiments, the insulation film25may be omitted. Further, in the fourth embodiment, the insulation film25D may be omitted. For example, if the encapsulation resin91does not contain the magnetic body (i.e., magnetic material), the insulation film25(or insulation films25D) for covering the coil substrate20is not necessary. Thus, the insulation film25(or insulation films25D) may be omitted. In this case, the encapsulation resin91does not contain a magnetic body that may cause short-circuiting. Thus, the encapsulation resin91may be formed directly on the coil substrate20.

In the first embodiment, the insulation layer51may be omitted. In this case, surface treatment such as the plasma process or the like is preferably performed on the lower surface30A of the substrate30to increase the adhesiveness of the substrate30and the wiring61. This also sufficiently ensures insulation between the wiring61and the wiring62with the substrate30.

In each embodiment and each modification described above, the number of windings of the wirings in the structural bodies41to47may be combined in any manner. The wiring of approximately one winding and the wiring of approximately ¾ of a winding may be combined as in the embodiment described above. Alternatively, the wiring of approximately one winding and the wiring of approximately ½ of a winding may be combined. The wiring of four types of patterns (wirings62,63,64,65in the example of the embodiment described above) becomes necessary if the wiring of approximately ¾ of a winding is used, and the helical coil can be formed with only the wirings of two types of patterns if the wiring of approximately ½ of a winding is used.

In the third embodiment, it has been described that the burr removal step may be performed after the stacked body23C is punched in a pressing (stamping) process to form the through hole23X and the opening20Y. In the same manner, the burr removal step may be performed in each of the first, second, and fourth embodiments. For example, in the first embodiment, the burr removal step may be performed after the steps illustrated inFIGS. 28A and 28B.

Clauses

This disclosure further encompasses various embodiments described below.

1. A method for manufacturing an inductor, the method including:

preparing a plurality of structural bodies, wherein each of the plurality of structural bodies includes a metal layer and an insulation layer formed on the metal layer;

forming a stacked body by sequentially stacking the plurality of structural bodies while connecting the metal layers of the plurality of structural bodies in series;

molding the stacked body to shape the metal layers of the plurality of structural bodies into wirings so that the wirings that are connected in series form a helical coil; and

forming a plurality of first discrete insulation films by performing electrodeposition so that the plurality of first discrete insulation films are spaced apart from each other and cover surfaces of the wirings exposed from a surface of the stacked body.

2. The method according to clause 1, wherein the forming a stacked body includes electrically connecting the metal layers of the plurality of structural bodies that are adjacent in a stacking direction of the stacked body with a plurality of through electrodes, the method further including

forming a plurality of second discrete insulation films by performing the electrodeposition so that the plurality of second discrete insulation films are spaced apart from each other and cover surfaces of at least two of the plurality of through electrodes that are exposed from the surface of the stacked body.