JP3131722B2 - Chip inductor and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip-shaped inductor in which a coil-shaped conductor is buried in a magnetic core and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4, a coiled conductor b is buried in a magnetic core a, both ends of which are extended in the axial direction to be exposed at both end surfaces of the magnetic core a, and external ends are provided on the both end surfaces. Electrode c
And a chip-shaped inductor formed as shown in FIG.
There is known a chip inductor in which a linear conductor b1 is embedded in a magnetic core a, both ends of which are exposed at both end surfaces of the magnetic core a, and external electrodes c are formed on the both end surfaces.

[0003]

According to the above-mentioned conventional chip-shaped inductor, the connection between both ends of the coil-shaped conductive wire b and the external electrode c is a point contact, so that the resistance of the contact is high. When a large current is applied to the coil-shaped conductive wire b, there is a problem in that disconnection or poor contact may occur at this portion.

[0004] The present invention solves the above-mentioned problems of the conventional chip inductor, reduces the contact resistance, and can cope with a large current and a chip inductor which can be manufactured easily and at low cost. It is intended to provide a manufacturing method.

[0005]

In order to achieve the above object, a chip-shaped inductor according to the present invention has a coil-shaped conductor buried inside a magnetic core, both ends of which are exposed at both end surfaces of the magnetic core. In a chip inductor in which both terminals are connected to external electrodes formed on both end faces of the magnetic core,
The winding pitch of the winding including the both ends is narrower than the winding pitch of the other windings, and the two ends are linearly exposed on both end surfaces of the magnetic core. The production method of the present invention
A core is formed by extruding a kneaded material obtained by kneading a magnetic material powder and a binder, and after winding a coil-shaped conductor wire wound alternately at a wide winding pitch and a narrow winding pitch on the core, By extruding the kneading material, a core is formed by surrounding the core in which the conductive wire is wound in a coil shape, and then the core and the core are baked to obtain a predetermined length and a narrow winding. Cutting at the pitch winding, a coil-shaped conductor is buried in the magnetic core to create a chip-shaped inductor base having both ends linearly exposed at both end faces of the magnetic core. Either the external electrodes are formed on both end surfaces, or a coiled conductive wire wound alternately at a wide winding pitch and a narrow winding pitch is wound around a core made of a sintered magnetic material. After that, the core formed by winding the conductive wire into a coil by extrusion molding of the kneading material Surround and form a jacket, and then fire the core and the jacket, cut at a predetermined length and at a narrow winding pitch, and embed the coiled conductor in the magnetic core A chip-shaped inductor base is formed with both ends linearly exposed at both end faces of the magnetic core, and external electrodes are formed on both end faces of the chip-shaped inductor base.

[0006]

As described above, in the chip-shaped inductor of the present invention, since both ends of the coil-shaped conductor exposed on both end faces of the magnetic core are linear, the chip-shaped inductor is formed on both end faces but has an area in contact with the external electrode. Becomes large and the contact with the external electrode becomes good. Therefore, the contact resistance is reduced, and when a large current flows through the coil-shaped conductor, heat generation at the contact portion is reduced. Therefore, disconnection or poor contact due to evaporation of the contact portion is reduced. According to the manufacturing method of the present invention, as described above, after winding a coiled conductor wound alternately at a wide winding pitch and a narrow winding pitch on the core, the extruding of the kneading material is performed to form the conductor. A coil is wound around the core to form an envelope, and then the core and the envelope are fired and then cut at a predetermined length and at a narrow winding pitch. Thus, the coil-shaped conductor is embedded in the magnetic core, and both ends of the coil-shaped conductor are formed in a linear manner to form a chip-shaped inductor body exposed at both end faces of the magnetic core. Therefore, the chip-shaped inductor can be manufactured continuously, easily and easily. It can be manufactured at low cost.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a rectangular parallelepiped magnetic core made of, for example, ferrite, and reference numeral 2 denotes a coiled conductive wire. The coiled conductive wire 2 is embedded inside the magnetic core 1, and both ends 3, 3 are exposed at both end surfaces of the magnetic core 1. The coiled conductive wire 2 has a winding pitch including both ends 3, 3 that is narrower than the winding pitch of the other windings. External electrodes 4 are formed on both end surfaces of the magnetic core 1 and both end portions of the peripheral surface connected to the end surfaces of the magnetic core 1.

Next, a method of manufacturing the chip inductor will be described. As shown in FIG. 2, the binder S and the magnetic material powder B having an appropriate mixing ratio are kneaded by a kneader 5 so that the magnetic material powder and the binder are homogenized.
The desired extruded, for example, a rod 8 having a circular cross section as a core having a diameter of 0.5 to 10 mm formed from an outlet of the primary extruder 7 is supplied to the next extruder 7 under pressure, for example, at 30 m / Extrude at a speed of seconds. After the rod body 8 is dried by, for example, a drier (not shown), a conductor 10 is alternately wound at a wide winding pitch and a narrow winding pitch by a winding machine 9, and the conductor 1 is dried.
The rod body 8 wound with 0 is fed into the secondary extruder 11.
The secondary extruder 11 has a kneader 5 in advance.
Since the kneading material 12 having a larger mixing ratio and a smaller shrinkage ratio than the kneading material 6 supplied to the primary extruder 7 under pressure is supplied under pressure, or the kneading material 12 having the same mixing ratio is supplied under pressure. The conductor 10 wound on the rod 8 by the machine 11 is covered with the kneading material 12 to form a jacket. After that, it is cut in accordance with the size of the firing furnace or the shape of the setter to be laid below, fired at 600 to 1000 ° C., for example, 900 ° C., and cut with a cutter in accordance with the dimensions of each inductor base. Since the windings are wound so that the interval between adjacent narrow winding pitches is equal to the length of each individual inductor body, cutting is performed at this position. Cut individual inductor substrate 1
3 is barrel-polishing with barrel powder and water to give a rounded corner.

As shown in FIG. 1, a coiled conductor 2 is embedded in a magnetic core 1 and both ends 3, 3 of the coiled conductor 2 are formed on both ends of the magnetic core 1 in an arc shape. It is linearly exposed. External electrodes 4 and 4 are formed by applying and baking a silver paste to both end surfaces of the inductor base 13 and both end portions of the peripheral surface connected thereto. External electrodes 3, 3
Is plated with nickel and solder.

The above-mentioned chip-shaped inductor is manufactured by the above-mentioned manufacturing method, but a conductor is wound on a fired circular rod having a circular cross section as shown in FIG. 2 and thereafter manufactured by the method shown in FIG. Can be.

In the above embodiment, both terminals are exposed in the form of a circular arc. However, the present invention is not limited to this. The terminals are U-shaped, U-shaped (FIG. 3A), and U-shaped. Deformation such as (FIG. 3B) is possible.

[0012]

According to the present invention, when the above structure is used, the connection between the two ends of the coiled conductor and the external electrode is in linear contact with each other. In this case, even if a large current flows, there is no effect of disconnection or poor contact at this portion, and there is an effect that the chip inductor can be manufactured easily and at low cost.

[Brief description of the drawings]

FIGS. 1A and 1B are a front view and a cross-sectional view of one embodiment of the present invention.

FIG. 2 is a diagram for explaining an example of the manufacturing method of the present invention for manufacturing the chip inductor.

FIGS. 3A and 3B are cross-sectional views of modifications of the above embodiment.

FIG. 4 is a front view of an example of a conventional chip inductor.

FIG. 5 is a front view of another example of the conventional chip inductor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Magnetic core 2 Coiled conductor 3 Terminal 4 External electrode 6, 12 Kneading material 7, 11 Extruder 13 Chip-shaped inductor base

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-302410 (JP, A) JP-A-8-191022 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01F 17 / 04,27 / 28,41 / 10

Claims (3)

(57) [Claims] 1. A chip-shaped conductor in which a coil-shaped conductive wire is buried inside a magnetic core, both ends of which are exposed at both end faces of the magnetic core, and both ends are connected to external electrodes formed on both end faces of the magnetic core. In the inductor, the winding pitch including the two ends is narrower than the other windings, and the two ends are linearly exposed at both end surfaces of the magnetic core. 2. A coiled wire formed by extruding a kneaded material obtained by kneading a raw material powder of magnetic material and a binder, and alternately winding the winding core with a wide winding pitch and a narrow winding pitch. After winding, the kneading material is extruded to form a jacket surrounding the core in which the conductive wire is wound in a coil shape, and then the core and the jacket are fired to a predetermined length. And cut at the place of the winding of a narrow winding pitch, to create a chip-shaped inductor body in which the coil-shaped conductor is embedded in the magnetic core and both ends are linearly exposed at both end surfaces of the magnetic core, A method of manufacturing a chip inductor, wherein external electrodes are formed on both end surfaces of the chip inductor base. 3. A coiled conductor wound alternately at a wide winding pitch and a narrow winding pitch is wound on a core made of a fired magnetic material, and the kneaded material is extruded to form a coil. Forming a jacket surrounding the winding core wound in a shape, and then cutting at a predetermined length and at a winding position of a narrow winding pitch after firing the core and the jacket, A coil-shaped conductive wire is embedded in a magnetic core, and both ends of the coil-shaped conductive wire are linearly exposed to form a chip-shaped inductor body exposed at both end faces of the magnetic core, and external electrodes are formed on both end faces of the chip-shaped inductor body. Manufacturing method of a chip-shaped inductor.