Inductor

Abstract

Provided is an inductor provided with: a magnetic core (11) obtained by mixing and pressure-molding a magnetic powder and a bonding agent; and coil elements (12) embedded in the magnetic core (11). The coil elements (12) comprise two flat plate coils and are such that a first coil element (12a) and a second coil element (12b) are provided so as to overlap in order from a first side surface (11c) side to a second side surface (11d) side. The end sections of the coil elements (12) respectively constitute external electrodes (13) by protruding from a bottom surface (11a) and bending along the bottom surface (11a), the first external electrode (13a) extending toward a first end surface (11e) and a second end surface (11f), and the second external electrode (13b) extending toward the second end surface (11d).

Description

Technical Field

[0001] The present invention relates to an inductor used in power supply circuits and the like.

Background Art

[0002] In recent years, large-scale integrated circuits such as CPUs have been trending toward lower operating voltages, and the required current for elements has reached tens of amperes. Meanwhile, there is growing demand for compact, low-profile power supply circuits. Multiphase power supply systems have been widely used to cope with increasing current requirements, and accordingly the coupling method has been adopted as a power supply system compatible with this architecture. The inductor used in this coupling method is driven by an inductor in which a plurality of coils are coupled with a coupling coefficient of approximately 0.6.

[0003] As for prior art document information related to the invention of this application, for example, Patent Document 1 is known.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0005] However, when there is a demand for even higher current, the conventional coupling method has its limitations. To address this issue, a system called a multiphase voltage regulator is currently under study. This system requires a significantly increased coupling between a plurality of coils, and sufficient characteristics cannot be obtained with the inductors used in conventional coupling methods. To increase the coupling coefficient, it is necessary to increase the facing area between the plurality of coils, which makes it difficult to lead out electrodes as in conventional coupled inductors. Furthermore, this system requires a plurality of inductors to be arranged side by side, which has also caused deterioration of electrical characteristics due to the wiring connecting these inductors.

[0006] The present invention aims to provide a small inductor that can handle high currents, is easy to wire, and has a large coupling coefficient. [Means for solving the problem]

[0007] To solve the above problems, the present invention comprises a rectangular parallelepiped-shaped magnetic core formed by mixing magnetic material powder and a binder and press-molding it, and a coil element embedded in the magnetic core. The magnetic core has a bottom surface, a top surface opposite the bottom surface, a first end surface connecting the bottom surface and the top surface, a second end surface opposite the first end surface, a first side surface connecting the bottom surface and the top surface, and a second side surface opposite the first side surface. When viewed from the top surface, the shape is rectangular, with the first and second end surfaces on the short side and the first and second side surfaces on the long side. The coil element consists of two flat coils and extends from the first side surface to the second side surface. The first coil element and the second coil element are stacked in that order, with the ends of each coil element protruding from the bottom surface and bent along the bottom surface to form external electrodes. The external electrode connected to the first coil element is called the first external electrode, and the external electrode connected to the second coil element is called the second external electrode. The ends of the first coil element are bent toward the first side surface, and the ends of the second coil element are bent toward the second side surface. The first external electrode is extended toward the first end surface and the second end surface, respectively, and the second external electrode is extended toward the second side surface. [Effects of the Invention]

[0008] The above configuration provides a compact inductor that can handle high currents, is easy to wire, and has a large coupling coefficient. [Brief explanation of the drawing]

[0009] [Figure 1] Perspective view of an inductor in one embodiment of the present invention [Figure 2] External view of an inductor in one embodiment of the present invention [Figure 3]Plan view of a coil element in one embodiment of the present invention [Figure 4] Top view of a circuit board on which an inductor is mounted according to one embodiment of the present invention. [Modes for carrying out the invention]

[0010] Hereinafter, an inductor according to one embodiment of the present invention will be described with reference to the drawings.

[0011] Figure 1 is a perspective view of an inductor according to one embodiment of the present invention, viewed from the bottom side. Figure 2 is an external view of the inductor according to one embodiment of the present invention, where Figure 2(a) is an external view of the side of the inductor according to one embodiment of the present invention, Figure 2(b) is an external view of the bottom side, and Figure 2(c) is an external view of the end face. In Figure 2, the internal coil element is shown by a dashed line.

[0012] An inductor in one embodiment of the present invention consists of a rectangular parallelepiped-shaped magnetic core 11 formed by mixing a magnetic material powder consisting of Fe-Si-Cr powder with a binder consisting of silicone and press-molding it, and a coil element 12 embedded in the magnetic core 11. The external shape of the magnetic core 11 is a rectangular parallelepiped with a width of approximately 6 mm, a length of approximately 13 mm, and a height of approximately 5 mm, and when viewed from above it is a rectangle with a width of approximately 6 mm and a length of approximately 13 mm. The magnetic core 11 has a bottom surface 11a on which the end of the coil element 12 protrudes, a top surface 11b opposite to the bottom surface 11a, a first end surface 11e provided on the part that connects the bottom surface 11a and the top surface 11b and is the short side when viewed from the top surface 11b side, a second end surface 11f opposite to the first end surface 11e, a first side surface 11c provided on the part that is the long side, and a second side surface 11d opposite to the first side surface 11c.

[0013] Two flat coil elements 12 are embedded inside the magnetic core 11. The first coil element 12a and the second coil element 12b are embedded in the magnetic core 11, facing each other in the planar direction, from the first side surface 11c to the second side surface 11d. The ends of each coil protrude from the bottom surface 11a of the magnetic core 11 and are bent along the bottom surface 11a to form an external electrode 13. Each coil element 12 is formed by punching out a copper plate, with a thickness of approximately 0.4 mm and a coil pattern width of approximately 0.8 mm. Furthermore, the surface of the coil element 12 embedded in the magnetic core 11 is provided with an insulating layer made of epoxy resin, phenolic resin, acrylic resin, etc., with a thickness of approximately 0.03 mm, by pad printing or the like.

[0014] Here, the external electrode 13 connected to the first coil element 12a is referred to as the first external electrode 13a, and the external electrode 13 connected to the second coil element 12b is referred to as the second external electrode 13b. The end of the first coil element 12a is bent toward the first side surface 11c to form the first external electrode 13a, and the end of the second coil element 12b is bent toward the second side surface 11d to form the second external electrode 13b. Furthermore, the tip of one of the first external electrodes 13a is extended toward the first end surface 11e, and the tip of the other first external electrode 13a is extended toward the second end surface 11f. The tips of the second external electrodes 13b are both extended toward the second side surface 11d.

[0015] Furthermore, the tip portion of the first external electrode 13a is bent along the first end face 11e or the second end face 11f. This is preferable because it makes it easier to form a solder fillet from the first external electrode 13a when mounted, improving the fixing force of the inductor and improving the visibility of the soldering state. On the other hand, it is preferable that the second external electrode 13b is not bent along the second side surface 11d. This makes it difficult to form a solder fillet on the second side surface 11d side, enabling high-density mounting.

[0016] Furthermore, the bottom surface 11a of the magnetic core 11 includes a portion from which the coil element 12 protrudes, and a recess 15 with a depth of approximately 0.4 mm is provided in the region connecting the first side surface 11c and the second side surface 11d. If the end of the coil element 12 is made to protrude from the bottom surface 11a and bent along the bottom surface 11a, a bulge will inevitably occur at the bent portion, resulting in poor stability when mounted. Therefore, as in this embodiment, by making the end of the coil element 12 protrude from the recess 15 provided on the bottom surface 11a of the magnetic core 11, the flatness of the mounting surface of this inductor can be improved. The depth of the recess 15 is preferably 80% or more and 200% or less of the thickness of the external electrode 13. If the depth of the recess is shallower than 80% of the thickness of the external electrode, the flatness will be poor. Conversely, if it exceeds 200%, the core volume will be small and the inductance value will decrease, which is undesirable.

[0017] Here, the coil element 12 will be described in more detail. Figure 3 is a plan view of a coil element in one embodiment of the present invention, where Figure 3(a) is a plan view of the first coil element 12a and Figure 3(b) is a plan view of the second coil element 12b. In Figure 3, the outer shape of the magnetic core 11 when these coil elements are embedded in the magnetic core 11 is shown by a dashed line. The ends of the coil elements that protrude outside the dashed line are bent along the bottom surface 11a after being embedded to form an external electrode 13. At this time, the parts of the two coil elements embedded in the magnetic core 11 overlap, while the parts that form the external electrode 13 do not overlap. Therefore, the coupling between the first coil element 12a and the second coil element 12b can be strengthened in the parts embedded in the magnetic core 11, and the parts that become the external electrode 13 can be easily bent to opposite sides. In Figure 3, the coil loop is rectangular, but the loop may also be rounded in an Ω shape.

[0018] With the above configuration, the end of the first coil element 12a and the end of the second coil element 12b project from the magnetic core 11 in close proximity to each other on the bottom surface 11a, which makes short circuits likely to occur during mounting. Therefore, it is desirable to provide the insulating layer 14 also in regions where the end of the first coil element 12a and the end of the second coil element 12b protrude from the magnetic core 11. In FIG. 2(b), hatching is applied to portions where the insulating layer 14 is provided for clarity. It is desirable that this insulating layer 14 is provided at the same time when an insulating layer is formed on the portion of the coil element embedded in the magnetic core 11. This configuration allows simplification of the process. Furthermore, when viewed from the first side surface 11c side, it is more preferable that regions of each external electrode 13 where the insulating layer 14 is not provided do not overlap. This configuration makes it difficult for short circuits to occur even when a plurality of inductors are mounted at high density, and is therefore more preferable.

[0019] FIG. 4 is a top view of a substrate for mounting an inductor according to an embodiment of the present invention. This substrate is provided with lands 16 for mounting a plurality of inductors, and is electrically connected to each other via wires 17 inside the substrate. In FIG. 4, positions where inductors are to be mounted are indicated by broken lines, and the land 16 portions are hatched. By mounting inductors on such a substrate, the second coil elements 12b of the plurality of inductors can be connected in series with each other. This configuration makes it possible to reduce the DC resistance between the second coil elements. Furthermore, since the second external electrode 13b is provided on the second side surface 11d side and is not provided on the first side surface 11c side, short circuits can be made less likely to occur even when mounting is performed with a reduced distance between adjacent inductors, which allows size reduction of equipment. [Industrial Applicability]

[0020] The inductor according to the present invention is small, can handle large currents, can provide an inductor with a large coupling coefficient, and is industrially useful. [Description of Reference Signs]

[0021] 11 Magnetic core 11a Bottom surface 11b Top surface 11c First side surface 11d Second side surface 11e First end surface 11f Second end surface 12 Coil element 12a First coil element 12b Second coil element 13 External electrode 13a First external electrode 13b Second external electrode 14 Insulating layer 15 Recess 16 Land 17 Wiring

Claims

1. The magnetic core comprises a rectangular parallelepiped formed by mixing magnetic material powder and a binder and press-molding it, and a coil element embedded in the magnetic core, the magnetic core having a bottom surface, a top surface opposite the bottom surface, a first end surface connecting the bottom surface and the top surface, a second end surface opposite the first end surface, a first side surface connecting the bottom surface and the top surface, and a second side surface opposite the first side surface, and having a rectangular shape when viewed from the top surface, with the first and second end surfaces on the short side and the first and second side surfaces on the long side, the coil element consists of two flat coils, with the first coil being formed sequentially from the first side surface toward the second side surface An inductor comprising a first coil element and a second coil element stacked on top of each other, wherein the ends of the first coil element each protrude from the bottom surface and are bent along the bottom surface to form external electrodes, the external electrode connected to the first coil element is called the first external electrode, and the external electrode connected to the second coil element is called the second external electrode, the end of the first coil element is bent toward the first side surface, the end of the second coil element is bent toward the second side surface, the first external electrode is extended toward the first end face and the second end face respectively, and the second external electrode is extended toward the second side surface.

2. The inductor according to claim 1, wherein an insulating layer is provided on a part of the surface of the external electrode, and the regions of the external electrode that are not provided with the insulating layer do not overlap when viewed from the first side.

3. The inductor according to claim 1, wherein the tip portion of the first external electrode is bent along the first end face or the second end face.

Images