inductor

Abstract

The purpose of the present invention is to obtain an inductor that can handle large currents, is small-sized, and has high reliability. The inductor comprises: a magnetic core (11) molded by pressing a mixture of a powder of magnetic material and a binder; a coil portion (12) disposed inside the magnetic core (11); and an outer electrode (13) formed by bending an end portion (12a) of the coil portion (12) protruding from the magnetic core (11). The coil portion (12) and the outer electrode (13) are made of flat conductive wires. The width of the end portion (12a) of the coil portion (12) protruding from the magnetic core (11) is less than an average width of the coil portion (12) disposed inside the magnetic core (11).

Description

[Technical Field]

[0001] The present disclosure relates to an inductor used in various electronic devices. [Background technology]

[0002] In recent years, as electronic devices have become more powerful, there has been a demand for smaller sizes and larger currents, creating a need for inductors that can satisfy both of these requirements.To address this, a magnetic core has been formed by embedding a coil element punched out from a flat conductor in a mixture of magnetic metal powder and a binder made of thermosetting resin, followed by pressure molding, and then bending the ends of the coil element that protrude from the side of the magnetic core to form terminals.

[0003] As prior art document information related to the present disclosure, for example, Patent Document 1 is known. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-19042 Summary of the Invention

[0005] However, to increase the strength of the terminal, it is necessary to widen the width of the flat conductor protruding from the magnetic core. If the thickness of the flat conductor is increased to reduce the DC resistance, force will be applied to the magnetic core when the end is bent to form the terminal, which may cause cracks.

[0006] An object of the present disclosure is to provide a small, highly reliable inductor that can handle large currents.

[0007] In order to solve the above problems, the inductor disclosed herein comprises a magnetic core formed by powdering magnetic material, mixing it with a binder, and then press-molding it, a coil portion disposed inside the magnetic core, and external electrodes formed by protruding the ends of the coil portion from the magnetic core and bending them, the coil portion and external electrodes being made of flat conductor wire, and the width of the ends of the coil portion protruding from the magnetic core being smaller than the average width of the coil portion disposed inside the magnetic core.

[0008] With the above-described configuration, the coil portion having its end protruding from the magnetic core can be easily bent, and a compact, highly reliable inductor capable of handling large currents can be provided. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view of an inductor according to an embodiment of the present disclosure. [Figure 2] 1 is a horizontal cross-sectional view of an inductor according to an embodiment of the present disclosure; [Figure 3] FIG. 10 is a horizontal cross-sectional view of another inductor according to the embodiment of the present disclosure. [Figure 4] 10 is a top perspective view of another inductor according to the embodiment of the present disclosure. [Figure 5] FIG. 10 is a perspective view of yet another inductor according to an embodiment of the present disclosure. [Figure 6] Horizontal cross section of the inductor shown in Figure 5 [Figure 7] 10 is a top perspective view of yet another inductor according to the embodiment of the present disclosure. [Figure 8] Cross section of the inductor shown in Figure 7 DETAILED DESCRIPTION OF THE INVENTION

[0010] An inductor 100 according to an embodiment of the present disclosure will now be described with reference to the drawings.

[0011] Fig. 1 is a see-through perspective view of inductor 100 according to an embodiment of the present disclosure, and in Fig. 1, parts hidden by the magnetic core are indicated by dashed lines. Fig. 2 is a horizontal cross-sectional view of the part of the inductor where the coil part is buried, taken along a plane passing through line II-II shown in Fig. 1 and parallel to bottom surface 11b of magnetic core 11.

[0012] The magnetic core 11 is formed by pressure molding a composite magnetic material containing magnetic powder and a binder. A coil portion 12 made of a flat conductor is embedded inside the magnetic core 11. Both ends 12a of the coil portion 12 protrude from both end faces 11a on opposite sides of the magnetic core 11. Each end 12a of the protruding coil portion 12 is bent to form an external electrode 13.

[0013] The magnetic core 11 has an external shape of approximately 5 mm square and a height of approximately 3 mm. The coil portion 12 and external electrode 13 are formed by punching a copper plate and are 0.3 mm thick. Both ends 12a of the coil portion 12 protrude from both end faces 11a of the magnetic core 11 to form two external electrodes 13. The end 13a of each external electrode 13 is embedded in the end face 11a of the magnetic core 11. The external electrodes 13 protrude from the end face 11a of the magnetic core 11 and are bent toward the bottom face 11b of the magnetic core 11. The end 13a of the external electrode 13 is located at the end where the external electrode 13 extends from the point where the coil portion 12 protrudes from the end face 11a along the width direction (direction of the Y axis) of the end face 11a.

[0014] 1 to 8, an XYZ orthogonal coordinate system is set. The X axis is an axis parallel to the direction connecting the two external electrodes 13 provided on both end faces 11a of the magnetic core 11, the Y axis is an axis parallel to the direction in which the external electrodes 13 extend along the end faces 11a from the places where the coil portions 12 protrude from the end faces 11a, and the Z axis is an axis perpendicular to both the X axis and the Y axis. The bottom face 11b of the magnetic core 11 is parallel to the XY plane. FIG. 2 can also be said to be a cross-sectional view taken along a plane passing through line II-II shown in FIG. 1 and parallel to the XY plane.

[0015] The average width of the coil portion 12 disposed inside the magnetic core 11 is approximately 1.2 mm, the width CEa of the end 12a of the coil portion 12 protruding from the magnetic core 11 is approximately 0.6 mm, and the width Ea of the external electrode 13 bent toward the bottom surface 11b of the magnetic core 11 is approximately 2.5 mm. Here, the average width of the coil portion 12 disposed inside the magnetic core 11 refers to the narrowest width at each point on the path through which the current flows, averaged over the path. Here, the "narrowest width at each point" refers to, for example, the length La at point A on the coil portion 12 in Figure 2, and the length Lb at point B on the coil portion 12.

[0016] Stable soldering can be ensured by making width Ea of external electrode 13 larger than width CEa of end 12a of coil portion 12 protruding from magnetic core 11. Furthermore, width EEa of end 13a of external electrode 13 is set to approximately 0.6 mm, and the width of the portion where end 13a of external electrode 13 is embedded in end face 11a of magnetic core 11 (hereinafter referred to as embedded portion 13e) is set to the same width EEa of end 13a of external electrode 13, approximately 0.6 mm, and embedded portion 13e is curved, thereby making it difficult for end 13a of external electrode 13 and embedded portion 13e to come out of magnetic core 11. Narrowing the width CEa of the end 12a of the coil portion 12 protruding from the magnetic core 11 tends to weaken the strength of the external electrode 13, but by burying the coil portion 12 connected to the end 12a of the coil portion 12 and the embedded portion 13e of the end 13a of the external electrode 13 in the end face 11a of the magnetic core 11 as in the configuration of the present disclosure, the strength of the external electrode 13 can be ensured.

[0017] In this way, when coil portion 12 made of flat conductor wire punched from a thick copper plate is embedded in magnetic core 11 and end 12a of coil portion 12 is bent so that it protrudes from magnetic core 11, forming external electrode 13, bending end 12a of coil portion 12 applies force to magnetic core 11, which may make cracks more likely to occur. This effect becomes particularly significant when the thickness of the flat conductor wire is 0.2 mm or more. In contrast, in the configuration of the present disclosure, width CEa of end 12a of coil portion 12 protruding from magnetic core 11 is smaller than the average width of coil portion 12 embedded in magnetic core 11, so that even if the thickness of the flat conductor wire is 0.2 mm or more, bending at end 12a of coil portion 12 is easy.

[0018] Since the thicker the flat conductor, the more difficult it is to bend, it is preferable to make the difference between the width CEa of the end 12a of the coil portion 12 protruding from the magnetic core 11 and the average width of the coil portion 12 arranged inside the magnetic core 11 greater than or equal to the thickness of the flat conductor.

[0019] While coil portion 12 in FIGS. 1 and 2 has a hook shape, it may also have a diagonal straight shape extending diagonally when magnetic core 11 is viewed from above, as shown in FIG. 3 . Alternatively, coil portion 12 may have a U-shape. FIG. 3 is a horizontal cross-sectional view of another inductor 200 according to an embodiment of the present disclosure, and is a cross-sectional view similar to FIG. 2 . In the inductor of FIG. 3 , coil portion 12 has an average width of approximately 1.9 mm, and end 12a of coil portion 12 protruding from magnetic core 11 has a width CEb of approximately 0.6 mm. This configuration provides a compact, highly reliable inductor 200 that can handle large currents.

[0020] In the above embodiment, the invention is applied to a 5 mm square inductor, but the effects of the present disclosure are particularly useful when the width of the end face 11a of the magnetic core 11 from which the end 12a of the coil portion 12 protrudes is 3 mm or more and 10 mm or less.

[0021] Fig. 4 is a top perspective view of another inductor 300 according to an embodiment of the present disclosure. In Fig. 4, the portion hidden by the magnetic core 11 is indicated by a dashed line.

[0022] The magnetic core 11 has an outer shape of approximately 4 mm square and a height of approximately 2.0 mm. The coil portion 12 and external electrode 13 are formed by punching a copper plate and are 0.2 mm thick. Both end portions 12a of the coil portion 12 protrude from opposite end faces 11a of the magnetic core 11, respectively, to form two external electrodes 13. The end portion 13a of each external electrode 13 is embedded in the end face 11a of the magnetic core 11. Other configurational features are the same as those in FIG. 1. As in the embodiment in FIG. 1, the external electrodes 13 protrude from the end face 11a of the magnetic core 11 and are bent toward the bottom face 11b of the magnetic core 11.

[0023] The average width of coil portion 12 is approximately 0.9 mm, the width CEc of end portion 12a of coil portion 12 protruding from magnetic core 11 is approximately 0.6 mm, and the width Ec of external electrode 13 bent onto bottom surface 11b of magnetic core 11 is approximately 1.4 mm, so that when this inductor 300 is viewed from above, coil portion 12 and external electrode 13 bent onto bottom surface 11b of magnetic core 11 do not overlap. This makes it possible to suppress a decrease in the inductance value of inductor 300 due to cancellation of the magnetic flux of external electrode 13 and the magnetic flux of coil portion 12, and to obtain a desired inductance value.

[0024] FIG. 5 is a perspective view of yet another inductor 400 according to an embodiment of the present disclosure, and FIG. 6 is a horizontal cross-sectional view of the same. FIG. 6 is a cross-sectional view of inductor 400 taken along a plane parallel to the XY plane and passing through line VI-VI shown in FIG. 5. In this inductor 400, coil portion 12 has two straight shapes. Magnetic core 11 has end faces 11c and 11d located opposite each other. One end face 11c of magnetic core 11 is provided with external electrode 13b connected to one coil portion 12 and external electrode 13c connected to the other coil portion 12. The other end face 11d of magnetic core 11 is provided with external electrode 13d connected to two coil portions 12. Width CEd of end portions 12a of coil portions 12 protruding from magnetic core 11 is smaller than the average width of coil portions 12 arranged inside magnetic core 11. When inductor 400 is mounted on a printed circuit board (not shown), external electrode 13b and external electrode 13c may be soldered to pads connected to the electrical circuit of the printed circuit board, and external electrode 13d may be soldered to a dummy pad that is not connected anywhere in the electrical circuit. In this way, an inductor with a high inductance value and external electrodes 13b and 13c at both ends can be obtained, and mountability can also be improved.

[0025] FIG. 7 is a top perspective view of yet another inductor 500 according to an embodiment of the present disclosure, and FIG. 8 is a cross-sectional view of the inductor 500 of FIG. 7 taken along line VIII-VIII. This inductor 500 is a small inductor 500 having a magnetic core 11 with an outer shape of approximately 4 mm square and a height of approximately 2.0 mm. The coil portion 12 and the external electrode 13 are formed by punching a copper plate and have a thickness of approximately 0.3 mm. The coil portion 12 is embedded in the magnetic core 11, and both end portions 12a thereof protrude from both end surfaces 11a of the magnetic core 11 on opposite sides. Each of the protruding end portions 12a is bent toward the end surface 11a and the bottom surface 11b of the magnetic core 11. End 12a of coil portion 12, which is the bent portion, and the portion of external electrode 13 extending from end face 11a of magnetic core 11 toward bottom face 11b of magnetic core 11, are configured to have recessed depressions 14 with a depth of approximately 0.1 mm and a length of approximately 0.4 mm. This reduces the force applied to magnetic core 11 when bending to form external electrode 13, and makes it possible to realize a small inductor 500 of 4 mm square or less, which is free from cracks and has a reduced DC resistance value. [Industrial Applicability]

[0026] INDUSTRIAL APPLICABILITY The inductor according to the present disclosure can be obtained as an inductor that can handle large currents, is small in size, and is highly reliable, and is therefore industrially useful. [Explanation of symbols]

[0027] 11 Magnetic core 11a, 11c, 11d end face 11b Bottom 12 Coil section 12a end 13, 13b, 13c, 13d external electrode 13a End 13e Buried part 14 Depression 100, 200, 300, 400, 500 inductors CEa, CEb, CEc, CEd Width of the end of the coil Ea, Ec Width of the outer electrode EEa Width of the end of the external electrode

Claims

1. A magnetic core made by powdering magnetic material, mixing it with a binder, and then press-molding it. a coil portion disposed inside the magnetic core; an external electrode formed by bending an end of the coil portion so that the end of the coil portion projects from the magnetic core, the coil portion and the external electrode are made of flat conductive wires, The width of the end of the coil portion protruding from the magnetic core is smaller than the average width of the coil portion disposed inside the magnetic core, The width of the coil portion, inside the magnetic core, connected to the end of the coil portion protruding from the magnetic core is the same as the width of the end of the coil portion protruding from the magnetic core. Inductor.

2. 2. The inductor according to claim 1, wherein the width of said external electrodes is greater than the width of the ends of said coil portions protruding from said magnetic core.

3. 2. The inductor according to claim 1, wherein the difference between the width of the end of the coil portion protruding from the magnetic core and the average width of the coil portion disposed inside the magnetic core is equal to or greater than the thickness of the flat conductor wire.

4. 2. The inductor according to claim 1, wherein the coil portion and the external electrode bent onto the bottom surface of the magnetic core do not overlap when viewed from above.

5. The inductor according to claim 1 , wherein the ends of the coil portion and the bent portions of the external electrodes have recesses that are recessed in the thickness direction.

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