JP7025685B2 - Coil device - Google Patents

Description

The present invention relates to a coil device.

Conventionally, as a coil device, the coil device described in Patent Document 1 is known. The coil device described in Patent Document 1 includes a toroidal core and a coil wound around the toroidal core.

However, the coil device described in Patent Document 1 requires a work of winding a wire around a toroidal core, and there is a possibility that the characteristics of the coil device may vary due to the unwinding of the coil.

Further, in the coil device described in Patent Document 1, the height of the coil device is unnecessary because the core having the winding is embedded and the end of the winding is connected to the pin terminal protruding from the upper surface of the case. It becomes difficult to reduce the height of the coil device.

Japanese Unexamined Patent Publication No. 2009-141004

The present invention has been made in view of such an actual situation, and an object of the present invention is to provide a low-profile coil device with little variation in magnetic characteristics.

In order to achieve the above object, the coil device according to the present invention is
With the core
The element body having the core inside and
At least a terminal electrode having a side surface portion facing the side surface of the element body,
It has a coil portion having a winding portion that surrounds the core in a coil shape.
The winding part is
A plurality of connecting conductors provided along the peripheral edge of the core and penetrating the element body from the upper surface to the lower surface of the element body.
It is formed on the upper surface and the lower surface of the element body, and has a conductor-to-conductor connecting portion that connects the ends of each of the plurality of connecting conductors.
The lead portion connected to the winding portion is connected to the side surface portion of the terminal electrode.

In the coil device according to the present invention, the coil portion has a winding portion that surrounds the core in a coil shape. The winding portion has a plurality of connecting conductors and a conductor-to-conductor connecting portion that connects the ends of the plurality of connecting conductors. That is, unlike the conventional coil, the winding portion in the present invention does not require winding of a wire. That is, it is possible to easily form a winding portion that surrounds the core in a coil shape only by providing a plurality of connecting conductors in the element main body and forming a connecting portion between the conductors. Therefore, in the present invention, it is possible to suppress the variation in the magnetic characteristics of the coil device (stabilize the magnetic characteristics) without causing the winding disorder in the winding portion.

Further, since the coil device according to the present invention does not require winding of the wire, the variation in the number of turns of the winding portion is small, and the inductance value of the coil device can be easily controlled. Further, in the coil device according to the present invention, it is possible to reduce the height as compared with the conventional coil device formed by embedding a wound core.

Further, in the coil device according to the present invention, the lead portion of the coil portion is connected to the side surface portion of the terminal electrode. Therefore, in this respect as well, it is possible to reduce the height of the coil device as compared with the conventional case.

Preferably, the lead portion is formed on at least one of the upper surface and the lower surface of the element body, and connects the end portion of any one of the plurality of connecting conductors with the side surface portion of the terminal electrode. With such a configuration, it is possible to prevent unnecessary routing of the lead portion as compared with the conventional case in which the lead portion is connected to the terminal electrode by routing the wire, and the magnetic characteristics of the coil device vary. Can be effectively suppressed.

The element body may have a plurality of the cores inside, each of the plurality of cores may be surrounded by the winding portion, and the coil portion may surround each of the plurality of cores. It may have a core-to-core connection portion that connects the surrounding winding portions to each other. With such a configuration, one coil portion is provided with a plurality of winding portions connected by a connection portion between cores. Therefore, even when the coil device includes a plurality of cores, it is possible to suppress variations in the magnetic characteristics of the coil device including the plurality of cores, and to reduce the size and height of the coil device. be able to.

Preferably, the lead portion, the conductor-to-conductor connection portion, and, if necessary, the core-to-core connection portion are composed of predetermined conductor patterns formed on the upper surface and the lower surface of the element body. With such a configuration, most of the coil portion can be formed by the conductor pattern, and the coil portion can be easily formed on the upper surface or the lower surface of the element main body. Further, the magnetic characteristics of the coil device can be easily controlled by appropriately changing the shape and size of the conductor pattern.

Preferably, a protective layer for protecting the coil portion is formed on at least one of the upper surface and the lower surface of the element body. With such a configuration, damage and oxidation of the coil portion can be suppressed, deterioration of the coil portion can be effectively prevented, and variations in the magnetic characteristics of the coil device can be effectively suppressed. can. Further, if the protective layer is formed on the upper surface or the lower surface of the element body, the upper surface or the lower surface of the element body can be easily attracted, held, and conveyed by the arm at the time of manufacturing the coil device.

Preferably, the terminal electrode is arranged on the upper surface portion formed on the upper surface of the element body and the protective layer formed on the lower surface of the element body. It has at least one of the lower surfaces. When a protective layer is formed on at least one of the upper surface and the lower surface of the element body, the surface (upper surface) of the lead portion of the coil portion is covered with the protective layer. Even if the surface of the lead portion is covered with a protective layer, it is possible to (electrically) connect the end face of the lead portion to the side surface portion of the terminal electrode, and ensure the continuity between the lead portion and the terminal electrode. be able to.

Preferably, a buffer layer for cushioning the difference in heat shrinkage between the core and the element body is formed on the surface of the core. With such a configuration, the internal stress that may occur at the boundary portion between the core and the element main body is relaxed, and cracks that may occur at the boundary portion can be prevented.

Preferably, the core constitutes a closed magnetic path. By surrounding the core in a coil shape along the closed magnetic path with a coil portion, it is possible to suppress variations in the magnetic characteristics of the coil device having the core constituting the closed magnetic path, and to reduce the height of the coil device. Can be planned.

The core may be a toroidal core.

Further, in order to manufacture the coil device, the method for manufacturing the coil device according to the present invention is as follows.
The process of burying the core inside the board and
A step of forming a plurality of through holes penetrating the substrate from the upper surface to the lower surface of the substrate along the peripheral edge of the core.
A connecting conductor is embedded in each of the plurality of through holes, and inter-conductor connecting portions for connecting the ends of the plurality of connecting conductors are formed on the upper surface and the lower surface of the substrate. The process of forming a coil portion having a winding portion that surrounds the core in a coil shape, and
The process of cutting the substrate in which the core is embedded to form the element body, and
It is characterized by having at least a step of forming a terminal electrode having a side surface portion facing the side surface of the element body on the element body and connecting the lead portion of the coil portion to the side surface portion.

In the method for manufacturing a coil device according to the present invention, a winding portion is formed in the element body after the core is embedded in the substrate (element body). That is, in the present invention, unlike the conventional case, since the winding portion is formed on the element body instead of being wound around the core, the winding portion is not disturbed. In addition, the height of the coil device can be effectively reduced.

FIG. 1A is a perspective view of a coil device according to an embodiment of the present invention. FIG. 1B is a partially enlarged perspective view of a coil portion and the like in the coil device. FIG. 1C is a partially enlarged cross-sectional view of the coil device along the IC-IC line shown in FIG. 1A. FIG. 1D is a partially enlarged perspective view of a terminal electrode in the coil device. FIG. 2A is a perspective view showing a process of manufacturing the coil device. FIG. 2B is a perspective view showing a continuation of the process of FIG. 2A. FIG. 2C is a perspective view showing a continuation of the process of FIG. 2B. FIG. 2D is another perspective view showing the steps following FIG. 2B.

Hereinafter, the present invention will be described based on the embodiments shown in the drawings.

As shown in FIG. 1A, the coil device 2 according to the embodiment of the present invention is a pulse transformer, and includes cores 5a to 5d, an element main body 4, a plurality of terminal electrodes 8, a first coil portion 6a, and the like. It has a second coil portion 6b. The coil device according to the present invention can be applied not only to a pulse transformer but also to other transformers, inductors, EMC filters or other coil devices.

The element main body 4 has a substantially rectangular parallelepiped shape (substantially a hexahedron), and has an upper surface 4a, a lower surface 4b on the opposite side of the upper surface 4a in the Z-axis direction, and four side surfaces 4c to 4f. The dimensions of the element body 4 are not particularly limited, but for example, the vertical (X-axis) dimension of the element body 4 is preferably 8 to 22 mm, and the horizontal (Y-axis) dimension is preferably 8 to 22 mm, which is high. The (Z-axis) dimension is preferably 4 to 6 mm. The element body 4 is preferably made of a thermosetting resin such as an epoxy resin containing a filler (for example, a glass filler). The element body 4 may be made of other synthetic resin such as phenol resin, polyester resin, polyurethane resin, and polyimide resin.

The element main body 4 has a plurality of (four in the illustrated example) cores 5a to 5d inside. The cores 5a to 5d are toroidal cores formed in a cylindrical shape and form a closed magnetic path. The cores 5a to 5d are composed of, for example, a ceramic core such as ferrite or a metal core. The cores 5a to 5d are formed so that the outer peripheral shape and the inner peripheral shape thereof are substantially circular when viewed from the plane direction, but the outer peripheral shape and the inner peripheral shape of the cores 5a to 5d are limited to this. It's not a thing. The outer peripheral shape and inner peripheral shape of the cores 5a to 5d may be, for example, a substantially square shape, a substantially rectangular shape, or any other shape when viewed from a plane direction.

The cores 5a to 5d have an upper surface and a lower surface facing each other in the Z-axis direction. The upper surfaces of the cores 5a to 5d face the upper surface 4a of the element body 4, and the lower surfaces of the cores 5a to 5d face the lower surface 4b of the element body 4. The core 5a is arranged around the corners of the side surface 4e and the side surface 4d of the element body 4, the core 5b is arranged around the corners of the side surface 4e and the side surface 4c of the element body 4, and the core 5c is the element. The core 5d is arranged around the corners of the side surface 4f and the side surface 4d of the main body 4, and the core 5d is arranged around the corners of the side surface 4f and the side surface 4c of the element main body 4.

In the present embodiment, a buffer layer (not shown) for cushioning (relaxing) the difference in heat shrinkage between the cores 5a to 5d and the element main body 4 is formed on the surface of the cores 5a to 5d. The buffer layer is preferably formed on at least one of the upper surface, the lower surface, the inner surface surface and the outer surface surface of the cores 5a to 5d. Examples of the material constituting the buffer layer include stress relaxation materials such as silicon-based resin. The thickness of the buffer layer is preferably 50 to 200 μm.

The first coil portion 6a and the second coil portion 6b form a primary coil and a secondary coil, respectively, and a pulse transformer is formed between them. FIG. 1A shows a set of two first coil portions 6a and a second coil portion 6b, one coil portion 6a, 6b is provided around the core 5a, 5b, and the other coil portion 6a, 6b is provided around the cores 5c and 5d. Since one coil portion 6a, 6b and the other coil portion 6a, 6b have the same configuration, the description of the other coil portion 6a, 6b will be omitted below.

The coil portions 6a and 6b have first lead portions 6a1 and 6b1, second lead portions 6a2 and 6b2, inter-core connection portions 6a3 and 6b3, and winding portions 6a4 and 6b4, respectively. The first lead portions 6a1 and 6b1 are formed at one end of the coil portions 6a and 6b, and the second lead portions 6a2 and 6b2 are formed at the other ends of the coil portions 6a and 6b.

The two winding portions 6a4 and 6b4 are formed between the first lead portions 6a1 and 6b1 and the second lead portions 6a2 and 6b2, respectively. One winding portion 6a4 or 6b4 coiled around the core 5a, and the other winding portion 6a4 or 6b4 coiled around the core 5b.

As shown in FIG. 1B, the winding portions 6a4 and 6b4 each have a plurality of connecting conductors 6a5 and 6b5 and inter-conductor connecting portions 6a6 and 6b6. As shown in FIG. 1B, a plurality of connecting conductors 6a5 and 6b5 (12 in the illustrated example) are provided along the inner peripheral edges of the cores 5c and 5d, and as shown in FIG. 1C, the upper surface of the element main body 4 is provided. It penetrates the element main body 4 from 4a (lower surface 4b) toward the lower surface 4b (upper surface 4a). In the following, when it is necessary to make a distinction, the connecting conductors 6a5 and 6b5 provided along the inner peripheral edges of the cores 5c and 5d are referred to as "inner peripheral side connecting conductors 6a5 and 6b5".

Further, as shown in FIG. 1B, a plurality of connecting conductors 6a5 and 6b5 (12 in the illustrated example) are provided along the outer peripheral edge of the cores 5c and 5d, and as shown in FIG. 1C, the element main body 4 is provided. The element body 4 penetrates from the upper surface 4a (lower surface 4b) to the lower surface 4b (upper surface 4a). In the following, when it is necessary to make a distinction, the connecting conductors 6a5 and 6b5 provided along the outer peripheral edge of the cores 5c and 5d are referred to as "outer peripheral side connecting conductors 6a5 and 6b5". The number of inner peripheral side connecting conductors 6a5 and 6b5 or the number of outer peripheral side connecting conductors 6a5 and 6b5 is not limited to the number shown in the figure, and may be changed as appropriate.

The connecting conductors 6a5 and 6b5 are composed of pin members having a needle-like (or substantially linear) shape. As shown in FIG. 1C, the connecting conductors 6a5 and 6b5 are formed so that the length in the Z-axis direction thereof is substantially equal to the thickness in the Z-axis direction of the element main body 4. Therefore, the upper ends 61a and 61b of the connecting conductors 6a5 and 6b5 are exposed from the upper surface 4a of the element body 4, and the lower ends 62a and 62b are exposed from the lower surface 4b of the element body 4. The exposed surface 610a of the upper end 61a is substantially flush with the upper surface 4a of the element body 4, and the exposed surface 620a of the lower end 62a is substantially flush with the lower surface 4b of the element body 4.

In the example shown in FIG. 1A, a predetermined gap is formed between the inner peripheral side connecting conductors 6a5 and 6b5 and the inner peripheral surface of the core 5, and between the outer peripheral side connecting conductors 6a5 and 6b5 and the outer peripheral surface of the core 5. A predetermined gap is formed in the. However, when the surface of the connecting conductors 6a5 and 6b5 is coated with an insulating coating, the predetermined gap may be omitted. As the insulating coating, an epoxy-modified acrylic resin or the like can be used.

The material constituting the connecting conductors 6a5 and 6b5 is not particularly limited, and examples thereof include a conductive material made of Cu, Ag, Au, Al, or an alloy thereof. The diameter of the pin member constituting the connecting conductors 6a5 and 6b5 is preferably 0.05 to 0.3 mm.

As shown in FIG. 1B, the interconductor connecting portions 6a6 and 6b6 are formed on the upper surface 4a and the lower surface 4b of the element main body 4, and connect the end portions of the plurality of connecting conductors 6a5 and 6b5 to each other. More specifically, as shown in FIGS. 1C and 2C, in the upper surface 4a of the element main body 4, the interconductor connecting portions 6a6 and 6b6 are exposed at the upper ends 61a and 61b of the inner peripheral side connecting conductors 6a5 and 6b5, respectively. The surfaces 610a and 610b are formed so as to connect the exposed surfaces 610a and 610b of the upper ends 61a and 61b of the outer peripheral side connecting conductors 6a and 6b5, respectively.

In the example shown in FIG. 2C, the exposed surfaces 610a and 610b of the upper ends 61a and 61b of the inner peripheral side connecting conductors 6a5 and 6b5 and the upper ends 61a and 61b of the outer peripheral side connecting conductors 6a5 and 6b5 adjacent to each other in the clockwise direction thereof. The exposed surfaces 610a and 610b of the above are connected by the interconductor connecting portions 6a6 and 6b6.

As shown in FIGS. 1C and 2D, in the lower surface 4b of the element main body 4, the inter-conductor connecting portions 6a6 and 6b6 are a plurality of exposed surfaces 620a of the lower ends 62a of each of the plurality of inner peripheral side connecting conductors 6a5 and 6b5. It is formed so as to connect to the exposed surface 620a of each lower end 62a of each of the outer peripheral side connecting conductors 6a5 and 6b5.

In the illustrated example, the exposed surfaces 620a, 620b of the lower ends 62a, 62b of the inner peripheral side connecting conductors 6a5, 6b5 and the lower ends 62a, 62b of the outer peripheral side connecting conductors 6a5, 6b5 adjacent to each other in the clockwise direction are exposed. The surfaces 620a and 620b are connected by conductor-to-conductor connecting portions 6a6 and 6b6.

In this way, the upper ends 61a and 61b of the inner peripheral side connecting conductors 6a6 and 6b6 are connected to the upper ends 61a and 61b of the outer peripheral side connecting conductors 6a5 and 6b5 via the inter-conductor connection portions 6a6 and 6b6. Then, the lower ends 62a and 62b of the outer peripheral side connecting conductors 6a5 and 6b5 are connected to the lower ends 62a and 62b of the other inner peripheral side connecting conductors 6a6 and 6b6 via the other inter-conductor connecting portions 6a6 and 6b6. Ru. By repeatedly making such a connection with the plurality of inner peripheral side connecting conductors 6a6, 6b6 and the plurality of outer peripheral side connecting conductors 6a6, 6b6, a coil shape (spiral shape) consisting of approximately 10 turns is formed. Winding portions 6a4 and 6b4 are formed.

As shown in FIG. 1A, the inter-core connecting portions 6a3 and 6b3 connect the winding portions 6a4 and 6b4 surrounding each of the plurality of (two in the illustrated example) cores 5c and 5d. In the illustrated example, the inter-core connecting portions 6a3 and 6b3 are connected between the winding portions 6a4 and 6b4 surrounding the core 5c and the winding portions 6a4 and 6b4 surrounding the core 5d. More specifically, as shown in FIG. 2C, the intercore connecting portions 6a3 and 6b3 are exposed at the upper ends 61a and 61b of any of the outer peripheral side connecting conductors 6a5 and 6b5 provided along the outer peripheral edge of the core 5c. Connect the surfaces 610a and 610b to the exposed surfaces 610a and 610b of the upper ends 61a and 61b of any of the outer peripheral side connecting conductors 6a and 6b5 provided along the outer peripheral edge of the core 5d different from the core 5c. ing.

In the illustrated example, the inter-core connection portions 6a3 and 6b3 are formed only on the upper surface 4a of the element body 4, but may be formed on the lower surface 4b of the element body 4. Further, the inter-core connection portions 6a3 and 6b3 extend along the outer periphery of the core 5c, but the method of routing the inter-core connection portions 6a3 and 6b3 is not limited to this and may be appropriately changed. ..

The first lead portions 6a1, 6b1 extend from the winding portions 6a4, 6b4 surrounding the core 5c toward the side surface 4d of the element main body 4. More specifically, the first lead portions 6a1, 6b1 have one end on the exposed surfaces 610a, 610b of the upper ends 61a, 61b of any of the plurality of inner peripheral side connecting conductors 6a5, 6b5 provided around the core 5c. It is connected, passes above the core 5c, bends once, and extends toward the side surface 4d of the element body 4. The end faces of the first lead portions 6a1 and 6b1 are exposed from the side surface 4d of the element main body 4 and are connected to the terminal electrodes 8 and 8 described later.

Of the first lead portions 6a1 and 6b1, the portions passing above the core 5c may be regarded as a part of the winding portions 6a4 and 6b4. In this case, the number of turns of the winding portions 6a4 and 6b4 surrounding the core 5c is 12 turns.

The second lead portions 6a2 and 6b2 extend from the winding portions 6a4 and 6b4 surrounding the core 5d toward the side surface 4c of the element main body 4. More specifically, the second lead portions 6a2 and 6b2 have one end on the exposed surfaces 610a and 610b of the upper ends 61a and 61b of any of the plurality of inner peripheral side connecting conductors 6a5 and 6b5 provided around the core 5d. It is connected, passes above the core 5d, bends a plurality of times, and extends toward the side surface 4c of the element body 4. The end faces of the second lead portions 6a2 and 6b2 are exposed from the side surface 4c of the element main body 4 and are connected to the terminal electrodes 8 and 8 described later.

Of the second lead portions 6a2 and 6b2, the portion passing above the core 5d may be regarded as a part of the winding portions 6a4 and 6b4. In this case, the number of turns of the winding portions 6a4 and 6b4 surrounding the core 5d is 12 turns.

Further, in the illustrated example, the first lead portions 6a1, 6b1 and the second lead portions 6a2, 6b2 are formed on the upper surface 4a of the element main body 4, but may be formed on the lower surface 4b of the element main body 4. It may be formed on both the upper surface 4a and the lower surface 4b of the element main body 4. Further, the first lead portions 6a1, 6b1 and the second lead portions 6a2, 6b2 connect the terminal portions 8 and 8 to any of the ends of the plurality of inner peripheral side connecting conductors 6a5 and 6b5. , Any one of the plurality of outer peripheral side connecting conductors 6a5 and 6b5 may be connected to the terminal electrodes 8 and 8.

The first lead portions 6a1, 6b1, the second lead portions 6a2, 6b2, the core-to-core connection portions 6a3, 6b3, and the conductor-to-conductor connection portions 6a6, 6b6 are on the same plane of the element body 4 (on the upper surface 4a and the lower surface 4b). ) Is composed of a predetermined conductor pattern (wiring) formed in). The conductor pattern is composed of a metal such as Ag, Ni, Cu or an alloy thereof. The conductor pattern may be made of the same material as the connecting conductors 6a5 and 6b5, or may be made of different materials. The thickness and width of the conductor pattern is preferably 3 to 30 μm. The conductor pattern can be formed by a method such as printing or plating, but in order to form the conductor pattern with high accuracy, it is preferable to form the conductor pattern by plating rather than printing.

As shown in FIG. 1A, a protective layer (protective film) 7 for protecting the coil portions 6a and 6b (conductor) is formed on the upper surface 4a and the lower surface 4b of the element main body 4. The protective layer 7 is a so-called resist, and is formed by coating, printing, plating, sputtering, or the like of a resist material. The protective layer 7 is made of, for example, an epoxy-based resin, and a material such as silicone can be used. The film thickness of the protective layer 7 is preferably 70 to 130 μm, more preferably 90 to 110 μm. In the illustrated example, the protective layer 7 is formed on both the upper surface 4a and the lower surface 4b of the element body 4, but may be formed on one of the upper surface 4a and the lower surface 4b of the element body 4.

The element main body 4 is formed with a plurality of (8 in the illustrated example) terminal electrodes 8 to which the first lead portions 6a1, 6b1 and the second lead portions 6a2, 6b2 of the coil portions 6a, 6b are connected. .. More specifically, four terminal electrodes 8 are formed on the side surface 4c side of the element body 4, and four terminal electrodes 8 are also formed on the side surface 4d side of the element body 4.

As shown in FIG. 1D, the terminal electrode 8 has a side surface portion 81, an upper surface portion 82, and a lower surface portion 83. As shown in FIG. 1A, the side surface portion 81 faces the side surfaces 4c and 4d of the element main body 4 and abuts on the side surfaces 4c and 4d. The upper surface portion 82 faces the upper surface 4a of the element main body 4 and is arranged on the upper surface 4a (more accurately, on the protective layer 7 formed on the upper surface 4a). The lower surface portion 83 faces the lower surface 4b of the element main body 4 and is arranged on the lower surface 4b (more accurately, on the protective layer 7 formed on the lower surface 4b). In the present embodiment, the lower surface portion 83 has a function as a mounting surface.

The height of the side surface portion 81 of the terminal electrode 8 in the Z-axis direction is the thickness of the element body 4 in the Z-axis direction, the thickness of the protective layer 7 formed on the upper surface 4a of the element body 4, and the thickness of the element body 4. It is formed so as to be substantially equal to the sum of the thickness of the protective layer 7 formed on the lower surface 4b.

In the present embodiment, the terminal electrode 8 is formed so as to straddle the side surface 4c (or the side surface 4d), the upper surface 4a, and the lower surface 4b of the element main body 4. However, the terminal electrode 8 may be formed at least on the side surface 4c (or the side surface 4d) of the element main body 4, and if the side surface portion 81 is provided, the upper surface portion 82 and / or the lower surface portion 83 may be omitted. You may.

The first lead portions 6a1 and 6b1 are connected to the side surface portions 81 and 81 of the terminal electrodes 8 and 8 arranged on the side surface 4d side of the element main body 4, whereby the winding portions 6a4 and 6b4 of the coil portions 6a and 6b are connected. Is connected to the terminal electrodes 8 and 8 via the first lead portions 6a1 and 6b1. Similarly, the second lead portions 6a2 and 6b2 are connected to the side surface portions 81 and 81 of the terminal electrodes 8 and 8 arranged on the side surface 4c side of the element main body 4, whereby the winding portions of the coil portions 6a and 6b are connected. 6a4 and 6b4 are connected to the terminal electrodes 8 and 8 via the second lead portions 6a2 and 6b2.

The terminal electrode 8 is composed of, for example, a laminated electrode film of a base electrode film and a plating film, and the base electrode film is composed of a conductive paste film containing a metal such as Sn, Ag, Ni, Cu or an alloy thereof. Yes, a plating film may be formed on the base electrode film. In this case, after the base electrode film is formed, a drying treatment or a heat treatment is performed, and then a plating film is formed. Examples of the plating film include metals such as Sn, Au, Ni, Pt, Ag, and Pd, or alloys thereof. The terminal electrode 8 may be formed by sputtering. The thickness of the terminal electrode 8 is preferably 3 to 30 μm.

Next, a method of manufacturing the coil device 2 of the present embodiment will be described. As shown in FIG. 2A, in the method of the present embodiment, first, a substrate 3 in which a plurality of cores 5 having a cushioning layer coated on the surface are embedded therein is prepared. In the illustrated example, the substrate 3 is divided into a plurality of regions by a plurality of planned cutting lines 10X extending in the X-axis direction and a plurality of planned cutting lines 10Y extending in the Y-axis direction, and inside each region. Has four cores 5 buried in each.

The method for molding the substrate 3 in which the plurality of cores 5 are embedded is not particularly limited, but for example, insert injection molding in which the plurality of cores 5 are arranged and molded inside the molding die. Or, powder forming is used (substrate forming process). The material of the molding die is not particularly limited, and plastic, metal, or the like may be appropriately selected as long as it can withstand the pressure during molding.

Next, as shown in FIG. 2B, a plurality of through holes 9 penetrating the substrate 3 from the upper surface 3a to the lower surface 3b of the substrate 3 are formed along the inner and outer peripheral edges of each of the plurality of cores 5. (Through hole forming step). The method for forming the through hole 9 is not particularly limited, and a cutting tool such as a drill, a laser, or the like may be used. In the illustrated example, 12 through holes 9 are formed on the inner peripheral side and the outer peripheral side of each core 5. The number of through holes 9 may be appropriately changed according to the number of turns of the winding portions 6a4 and 6b4 of the coil portions 6a and 6b to be formed.

Next, the connecting conductors 6a5 and 6b5 are embedded inside each of the plurality of (inner peripheral side: 12 pieces, outer peripheral side: 12 pieces) through holes 9 (connecting conductor burying step). In the connection conductor burying step, the upper ends 61a, 61b and the lower ends 62a, 62b of the connecting conductors 6a5, 6b5 are exposed from the upper surface 3a and the lower surface 3b of the substrate 3, respectively, and the exposed surfaces 610a, 610b and the exposed surfaces 620a, 620b are exposed. The connecting conductors 6a5 and 6b5 are embedded so that the above appears (see FIG. 1C).

Next, as shown in FIGS. 1C and 2D, on the lower surface 3b of the substrate 3, the exposed surfaces of the lower ends 62a and 62b of each of the plurality of (12 in the illustrated example) inner peripheral side connecting conductors 6a5 and 6b5. The 620a, 620b and the exposed surfaces 620a, 620b of the lower ends 62a, 62b of each of the plurality of (12 in the illustrated example) outer peripheral side connecting conductors 6a5, 6b5 are connected by a conductor pattern. As a result, on the lower surface 3b of the substrate 3, the lower ends 62a, 62b of each of the plurality (12) inner peripheral side connecting conductors 6a5, 6b5 and the plurality (12) outer peripheral side connecting conductors 6a5, 6b5 are formed. Inter-conductor connection portions 6a6 and 6b6 connecting the lower ends 62a and 62b are formed (conductor-to-conductor connection portion forming step).

The method for forming the conductor pattern is preferably performed by a plating method, but may be performed by printing. The same applies to the inter-core conductor pattern forming step described later.

Further, as shown in FIGS. 1C and 2C, on the upper surface 3a of the substrate 3, the exposed surfaces 610a of the upper ends 61a and 61b of each of the plurality of (10 in the illustrated example) inner peripheral side connecting conductors 6a5 and 6b5. , 610b and the exposed surfaces 610a and 610b of the upper ends 61a and 61b of each of the plurality of (10 in the illustrated example) outer peripheral side connecting conductors 6a and 6b5 are connected by a conductor pattern. As a result, on the upper surface 3a of the substrate 3, the upper ends 61a, 61b of each of the plurality (10) inner peripheral side connecting conductors 6a5, 6b5 and the plurality (10) outer peripheral side connecting conductors 6a5, 6b5 are formed. Inter-conductor connection portions 6a6 and 6b6 connecting the upper ends 61a and 61b are formed (conductor-to-conductor connection portion forming step).

As described above, by performing the interconductor-to-conductor connection portion forming step on the upper surface 3a and the lower surface 3b of the substrate 3, the wound portions 6a4 and 6b4 that surround the core 5 in a coil shape are formed.

Further, on the upper surface 3a of the substrate 3, for the two cores 5 adjacent to each other in the Y-axis direction, the upper end 61a of any one of the plurality of outer peripheral side connecting conductors 6a5 and 6b5 provided along the peripheral edge of one core 5. The exposed surfaces 610a and 610b of 61b and the exposed surfaces 610a and 610b of the upper ends 61a and 61b of any of the plurality of outer peripheral side connecting conductors 6a and 6b5 provided along the peripheral edge of the other core 5 are formed by a conductor pattern. Connect (core-to-core conductor pattern forming process). The intercore conductor pattern forming step is performed at the same time as the above-mentioned interconductor connecting portion forming step.

As a result, the winding portions 6a4 and 6b4 surrounding each of the two cores 5 adjacent to each other in the Y-axis direction are connected by a conductor pattern. Although detailed illustration is omitted, the conductor pattern formed in the intercore conductor pattern forming step is formed with a conductor pattern formed across the planned cutting line 10X and without straddling the planned cutting line 10X. It is roughly divided into the conductor pattern. In the inter-core conductor pattern forming step, the conductor pattern may be bent if necessary.

Next, a resist is printed on the upper surface 3a and the lower surface 3b of the substrate 3 to form the protective layer 7 (protective layer forming step). A protective layer 7 is formed on the bottom surface of the molding die in advance, and the resin constituting the substrate 3 is filled inside the molding die from above, whereby the protective layer 7 is formed on the lower surface 3b. A certain substrate 3 may be obtained.

Next, the substrate 3 is cut along the planned cutting lines 10X and 10Y, and is separated into a plurality of element main bodies 4 (board cutting step). As a result, the element main body 4 in which a plurality of (4 in the illustrated example) cores 5c to 5d are embedded is obtained. The method for cutting the substrate 3 is not particularly limited, and a cutting tool such as a dicing saw or a wire saw, a laser, or the like may be used. From the viewpoint of ease of cutting, it is preferable to use a dicing saw having a sharp cut surface.

Here, in the substrate cutting step, the conductor pattern formed across the planned cutting line 10X is also cut in the inter-core conductor pattern forming step. Of the conductor patterns, the conductor patterns arranged on the positive direction side of the Y axis are the first lead portions 6a1 and 6b1 of the element main body 4 arranged on the positive direction side of the Y axis. On the other hand, among the conductor patterns, the conductor patterns arranged on the Y-axis negative direction side are the second lead portions 6a2, 6b2 of the element main body 4 arranged on the Y-axis negative direction side. Become.

The cut surface (end surface) of the first lead portions 6a1 and 6b1 is exposed from the side surface 4d which is the cut surface of the element main body 4. Further, the cut surface (end surface) of the second lead portions 6a2 and 6b2 is exposed from the side surface 4c which is the cut surface of the element main body 4.

On the other hand, the conductor pattern formed in the inter-core conductor pattern forming step without straddling the planned cutting line 10X is not cut in the substrate cutting step, and each of the two cores adjacent to each other in the Y-axis direction is formed. The winding portions 6a4 and 6b4 that surround the periphery are connected to the cores 6a3 and 6b3.

As described above, the coil portions 6a and 6b having the first lead portions 6a1, 6b1, the second lead portions 6a2 and 6b2, the core-to-core connection portions 6a3 and 6b3 and the winding portions 6a4 and 6b4 are formed on the element body 4. be able to.

Next, as shown in FIG. 1A, the terminal electrode 8 is formed on the element main body 4 provided with the coil portions 6a and 6b by the paste method and / or the plating method, and is subjected to a drying treatment or a heat treatment as necessary. Terminal electrode forming process). In the present embodiment, the four terminal electrodes 8 are formed so as to straddle the upper surface 4a, the lower surface 4b, and the side surface 4c of the element body 4, and the upper surface 4a, the lower surface 4b, and the side surface of the element body 4 are formed. Four terminal electrodes 8 are formed so as to straddle 4d. Further, the terminal electrode 8 is formed so as to cover the end faces of the first lead portions 6a1 and 6b1 exposed from the side surface 4d with the side surface portions 81, and the end faces of the second lead portions 6a2 and 6b2 exposed from the side surface 4c are formed. The terminal electrode 8 is formed so as to be covered with the side surface portion 81.

As a result, the terminal electrodes 8 and 8 are connected to the end faces of the first lead portions 6a1 and 6b1 exposed from the side surface 4d, and the terminal electrodes 8 and 8 are connected to the end faces of the second lead portions 6a2 and 6b2 exposed from the side surface 4c. To. As a method for forming the terminal electrode 8, it is preferable to perform screen printing using sputtering or silver paste. This is because the terminal electrode 8 can be formed thin by these methods.

In the above manufacturing method, the substrate forming step, the through hole forming step, the connecting conductor embedding step, the inter-conductor connecting portion forming step, the inter-core conductor pattern forming step, the protective layer forming step, the substrate cutting step, and the terminal electrode forming step. Although each step was performed in order, the substrate cutting step may be performed after the substrate molding step. In this case, each step after the through hole forming step is performed for each of the plurality of element main bodies 4 obtained through the substrate cutting step.

Alternatively, in the substrate forming step, a substrate having the same size as that of the element main body 4 may be formed, and in this case, the substrate cutting step can be omitted. Alternatively, the order of the conductor-to-conductor connection portion forming step and the core-to-core conductor pattern forming step may be exchanged.

In the present embodiment, the coil portions 6a and 6b have winding portions 6a4 and 6b4 that surround the cores 5a to 5d in a coil shape. The winding portions 6a4 and 6b4 have a plurality of connecting conductors 6a5 and 6b5, and inter-conductor connecting portions 6a6 and 6b6 for connecting the respective ends of the plurality of connecting conductors 6a5 and 6b5. That is, unlike the conventional coil, the winding portions 6a4 and 6b4 in the present embodiment do not require winding of a wire. Therefore, simply by providing a plurality of connecting conductors 6a5 and 6b5 on the element main body 4 and forming the interconductor connecting portions 6a6 and 6b6, the winding portions 6a4 and 6b4 that surround the cores 5a to 5d in a coil shape can be easily formed. It is possible to form. Therefore, in the present embodiment, the winding portions 6a4 and 6b4 are not disturbed, and the variation in the magnetic characteristics of the coil device 2 can be suppressed (the magnetic characteristics are stabilized).

Further, since the coil device 2 according to the present embodiment does not require winding of the wire, the variation in the number of turns of the winding portions 6a4 and 6b4 is small, and the inductance value of the coil device 2 can be easily controlled. .. Further, in the coil device 2 according to the present embodiment, it is possible to reduce the height as compared with the conventional coil device formed by embedding a wound core.

Further, in the coil device 2 according to the present embodiment, the first lead portions 6a1, 6b1 and the second lead portions 6a2, 6b2 of the coil portions 6a, 6b are connected to the side surface portions 81, 81 of the terminal electrodes 8, 8. .. Therefore, also in this respect, it is possible to reduce the height of the coil device 2 as compared with the conventional case.

Further, in the present embodiment, the first lead portions 6a1, 6b1 and the second lead portions 6a2, 6b2 are formed on the upper surface 4a of the element main body 4, and the upper end 61a of any one of the plurality of connecting conductors 6a5, 6b5 is formed. , 61b and the side surface portions 81, 81 of the terminal electrodes 8 and 8 are connected. Therefore, it is possible to prevent unnecessary routing of the first lead portions 6a1, 6b1 and the second lead portions 6a2, 6b2 as compared with the conventional case in which the lead portion is connected to the terminal electrode by routing the wire. It is possible to effectively suppress variations in the magnetic characteristics of the device 2.

Further, in the present embodiment, the element main body 4 has a plurality of cores 5a to 5d inside, and each of the plurality of cores 5a to 5d is surrounded by winding portions 6a4 and 6b4, and the coil portions 6a, The 6b has intercore connecting portions 6a3 and 6b3 for connecting the winding portions 6a4 and 6b4 surrounding each of the plurality of cores 5a to 5d. Therefore, one coil portion 6a, 6b is provided with a plurality of winding portions 6a4, 6b4 connected by the intercore connecting portions 6a3, 6b3. Therefore, even when the coil device 2 includes a plurality of cores 5a to 5d, it is possible to suppress variations in the magnetic characteristics of the coil device 2 including the plurality of cores 5a to 5d, and the coil device 2 It is possible to reduce the size and height of the coil.

Further, in the present embodiment, the first lead portions 6a1, 6b1, the second lead portions 6a2, 6b2, the conductor-to-conductor connection portions 6a6, 6b6, and the core-to-core connection portions 6a3, 6b3 are formed on the upper surface 4a and the lower surface 4b of the element main body 4. It is composed of a predetermined conductor pattern that is formed. Therefore, most of the coil portions 6a and 6b can be formed by the conductor pattern, and the coil portions 6a and 6b can be easily formed on the upper surface 4a and the lower surface 4b of the element main body 4. Further, the magnetic characteristics of the coil device 2 can be easily controlled by appropriately changing the shape and size of the conductor pattern.

Further, in the present embodiment, a protective layer 7 for protecting the coil portions 6a and 6b is formed on at least one of the upper surface 4a and the lower surface 4b of the element main body 4. Therefore, damage and oxidation of the coil portions 6a and 6b are suppressed, deterioration of the coil portions 6a and 6b can be effectively prevented, and variations in the magnetic characteristics of the coil device 2 can be effectively suppressed. can. Further, since the protective layer 7 is formed on the upper surface 4a or the lower surface 4b of the element body 4, the upper surface 4a or the lower surface 4b of the element body 4 is easily attracted and held by the arm at the time of manufacturing the coil device 2. Can be transported.

Further, in the present embodiment, the terminal electrode 8 is a protective layer formed on the upper surface portion 82 arranged on the protective layer 7 formed on the upper surface 4a of the element main body 4 and the lower surface 4b of the element main body 4. It has at least one of the lower surface portions 83 arranged on the 7. When the protective layer 7 is formed on at least one of the upper surface 4a and the lower surface 4b of the element body, the surface (upper surface) of the first lead portions 6a1, 6b1 and the second lead portions 6a2, 6b2 of the coil portions 6a, 6b is the protective layer 7. Will be covered with. Even if the surfaces of the first lead portions 6a1, 6b1 and the second lead portions 6a2, 6b2 are covered with the protective layer 7, the first lead portions 6a1, 6b1 and the second lead portions 6a1, 6b1 and the second lead portions 6a1, 6b1 are formed on the side surface portions 81, 81 of the terminal electrodes 8, 8. It is possible to (electrically) connect the end faces of the lead portions 6a2 and 6b2, and ensure that the first lead portions 6a1, 6b1 and the second lead portions 6a2 and 6b2 are electrically connected to the terminal electrodes 8 and 8. Can be done.

Further, in the present embodiment, a buffer layer for cushioning the difference in heat shrinkage between the cores 5a to 5d and the element main body 4 is formed on the surface of the cores 5a to 5d. Therefore, the internal stress that may occur at the boundary portion between the cores 5a to 5d and the element main body 4 is relaxed, and cracks that may occur at the boundary portion can be prevented.

Further, in the present embodiment, the cores 5a to 5d form a closed magnetic path. By surrounding the cores 5a to 5d in a coil shape along the closed magnetic path with the coil portions 6a and 6b, it is possible to suppress variations in the magnetic characteristics of the coil device 2 having the cores 5a to 5d constituting the closed magnetic path. At the same time, the height of the coil device 2 can be reduced.

Further, in the method for manufacturing the coil device 2 according to the present embodiment, after the cores 5a to 5d are embedded in the substrate 3 (element body 4), the winding portions 6a4 and 6b4 are formed in the element body 4. That is, in the present embodiment, unlike the conventional case, the winding portions 6a4 and 6b4 are formed on the element main body 4 instead of being wound around the cores 5a to 5d, so that the winding portions 6a4 and 6b4 are disturbed. Never. In addition, the height of the coil device 2 can be effectively reduced.

The present invention is not limited to the above-described embodiment, and can be variously modified within the scope of the present invention. For example, in the above embodiment, the connecting conductors 6a5 and 6b5 are made of pin members, but for example, the inner wall of the through hole 9 formed in the substrate 3 may be plated or various metals may be printed. The connecting conductors 6a5 and 6b5 may be configured.

Further, in the above embodiment, the element main body 4 has four cores 5a to 5d inside, but may have three or less cores, or may have five or more cores. You may.

Further, in the above embodiment, the connecting conductors 6a5 and 6b5 are embedded in the through holes 9 formed in the substrate 3 to obtain the substrate 3 in which the connecting conductors 6a5 and 6b5 are embedded. However, the method for obtaining the substrate 3 is not limited to this, and for example, the connecting conductors 6a5 and 6b5 are arranged in advance at predetermined positions inside the molding die, and the substrate 3 is configured on the connecting conductors 6a5 and 6b5. The substrate 3 in which the connecting conductors 6a5 and 6b5 are embedded may be obtained by filling the inside of the molding die with the resin to be formed.

Further, in the above embodiment, the element main body 4 has a substantially rectangular shape when viewed from the plane direction, but may have a substantially square shape when viewed from the plane direction.

Further, in the above embodiment, magnetic powder (ferrite or metallic magnetic powder) may be dispersed in the main component constituting the element main body 4.

Further, in the above embodiment, the coil device 2 may be used as an inductor. For example, the core 5a is surrounded by a winding portion 6a4, one end of the winding portion 6a4 is connected to the terminal electrode 8 by the first lead portion 6a1, and the other end is connected to the other terminal electrode 8 by the second lead portion 6a2. By connecting, the inductor can be configured.

Further, in the above embodiment, the connecting conductors 6a5 and 6b5 have a substantially linear shape, but may have a bent shape.

Further, the relationship between the primary coil and the secondary coil described above may be reversed. That is, the first coil portion 6a may form the secondary coil, and the second coil portion 6b may form the primary coil.

2 ... Coil device 3 ... Substrate 3a ... Top surface 3b ... Bottom surface 4 ... Element body 4a ... Top surface 4b ... Bottom surface 4c, 4d, 4e, 4f ... Side surfaces 5, 5a, 5b, 5c, 5d ... Core 6 ... Coil part 6a ... 1st coil part 6a1 ... 1st lead part 6a2 ... 2nd lead part 6a3 ... Core-to-core connection part 6a4 ... Wind Rotation part 6a5 ・ ・ ・ Connection conductor 61a ・ ・ ・ Upper end
610a ... Exposed surface 62a ... Lower end
620a ... Exposed surface 6a6 ... Conductor-to-conductor connection part 6b ... Second coil part 6b1 ... First lead part 6b2 ... Second lead part 6b3 ... Core-to-core connection part 6b4 ... Winding part 6b5 ・ ・ ・ Connection conductor 61b ・ ・ ・ Upper end
610b ... Exposed surface 62b ... Lower end
620b ・ ・ ・ Exposed surface 6b6 ・ ・ ・ Connection between conductors 7 ・ ・ ・ Protective layer 8 ・ ・ ・ First terminal electrode 81 ・ ・ ・ Side surface 82 ・ ・ ・ Top surface 83 ・ ・ ・ Bottom surface 9 ・ ・ ・Through hole

Claims (8)

With the core
An element body having the core inside, an upper surface, a lower surface on the opposite side of the upper surface in the height direction, and four side surfaces .
A pair of terminal electrodes arranged on at least a pair of opposite side surfaces of the element body and having side surface portions facing the side surfaces, respectively .
It has a coil portion having a winding portion that surrounds the core in a coil shape.
The winding part is
A plurality of connecting conductors provided along the peripheral edge of the core and penetrating the element body from the upper surface to the lower surface of the element body.
It is formed on the upper surface and the lower surface of the element body, and has a conductor-to-conductor connecting portion that connects the ends of each of the plurality of connecting conductors.
A pair of lead portions connected to one end and the other end of the winding portion are each exposed from the corresponding positions of the pair of facing side surfaces of the element body and connected to the side surface portions of the pair of terminal electrodes. Being done
The element body has a plurality of the cores inside, and the element body has a plurality of the cores inside.
Each of the plurality of cores is surrounded by the winding portion and is surrounded by the winding portion.
The coil portion has a core-to-core connection portion for connecting winding portions surrounding each of the plurality of cores.
A coil device characterized in that the lead portion, the conductor-to-conductor connection portion, and the core-to-core connection portion are formed of predetermined conductor patterns formed on the upper surface and the lower surface of the element main body. The lead portion is formed on at least one of the upper surface and the lower surface of the element body, and is characterized in that the end portion of any one of the plurality of connecting conductors is connected to the side surface portion of the terminal electrode. The coil device according to claim 1. The coil device according to claim 1 or 2 , wherein a protective layer for protecting the coil portion is formed on at least one of the upper surface and the lower surface of the element body. The terminal electrodes are an upper surface portion arranged on the protective layer formed on the upper surface of the element body and a lower surface portion arranged on the protective layer formed on the lower surface of the element body. The coil device according to claim 3, wherein the coil device has at least one of them. The invention according to any one of claims 1 to 4, wherein a buffer layer for cushioning the difference in heat shrinkage between the core and the element main body is formed on the surface of the core. The coil device described. The coil device according to any one of claims 1 to 5, wherein the core constitutes a closed magnetic path. The coil device according to any one of claims 1 to 6, wherein the core is a toroidal core. The process of burying multiple cores inside the board,
A step of forming a plurality of through holes penetrating the substrate from the upper surface to the lower surface of the substrate along the peripheral edge of each of the plurality of cores.
A connecting conductor is embedded in each of the plurality of through holes, and inter-conductor connecting portions for connecting the ends of the plurality of connecting conductors are formed on the upper surface and the lower surface of the substrate. A step of forming a coil portion having a plurality of winding portions that surround each of the cores in a coil shape.
The process of forming the inter-core connection portion connecting the plurality of winding portions, and
The process of cutting the substrate in which the plurality of cores are embedded to form the element body, and
It has a step of forming at least a terminal electrode having a side surface portion facing the side surface of the element body on the element body and connecting the lead portion of the coil portion to the side surface portion.
The lead portion, the conductor-to-conductor connection portion, and the core-to-core connection portion are configured by forming predetermined conductor patterns on the upper surface and the lower surface of the element body.
In the step of burying the core, the plurality of cores are embedded in each of the plurality of regions of the substrate divided by the planned cutting line.
In the step of forming the through hole, a plurality of the through holes are formed for each of the embedded cores.
In the step of forming the coil portion, the coil portion having the plurality of winding portions is formed in each of the plurality of the regions of the substrate.
In the step of forming the inter-core connection portion, a conductor pattern for connecting the winding portions surrounding the cores adjacent to each other in a predetermined direction on the substrate is formed.
In the step of forming the element main body, the conductor pattern formed by cutting the substrate along the planned cutting line without straddling the planned cutting line is used as the inter-core connection portion. The conductor pattern formed across the planned cutting line is cut to form the lead portion, and a plurality of element bodies having the inter-core connection portion and the lead portion are formed. The manufacturing method of the coil device.

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