JPH08264322A - Chip inductor - Google Patents

Abstract

PURPOSE: To provide a chip-inductor which is smaller in height than a conventional one where a coiled wire wound like a circle is buried in a magnetic core. CONSTITUTION: A coiled wire 2 wound like rectangles is buried in a rectangular parallelepipedic magnetic core 1, and an outer electrode 3 is formed on each end face of the magnetic core 1 and its vicinity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip type inductor in which a coil-shaped conductor is embedded in a magnetic core.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 5, a coil-shaped conductive wire b wound in a circular shape is embedded in a rectangular parallelepiped magnetic core a, and both ends thereof are connected to an external electrode c formed on the magnetic core a. Connected chip inductors have been proposed.

[0003]

In the above-mentioned chip-shaped inductor, since the coil-shaped conductive wire b is embedded in the magnetic core a, a closed magnetic path is formed, and the chip-shaped inductor has a small size and a high inductance value. However, when mounted on a printed circuit board, a chip-shaped inductor having a low height is desired due to a demand for miniaturization of electronic devices including the printed circuit board.

In view of such circumstances, it is an object of the present invention to obtain a flat chip inductor.

[0005]

In order to achieve the above object, the present invention provides a chip-type inductor in which a coil-shaped conductor is embedded in a rectangular parallelepiped magnetic core, wherein the coil-shaped conductor has a square shape. It is characterized in that it is wound in a rectangular shape or in an elliptical shape.

[0006]

When a current flows through the coil-shaped conducting wire wound in a square shape or an elliptical shape, the magnetic flux flows through the closed magnetic circuit in the magnetic core, and a predetermined impedance value is generated.

When the length of each turn of the coil-shaped conductor is made equal to the length of each turn of the coil-shaped conductor wound in a circular shape, the impedance values are substantially equal, while the high value of the chip-type inductor is high. Is low.

[0008]

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 in which a coil-shaped conductor 2 is embedded. External electrodes 3 and 3 made of a conductive film are formed, and the coil-shaped conductor 2 is formed by winding the conductor into a flat rectangular shape as shown in the drawing. The dimensions of the magnetic core portion 4 inside the magnetic core 1 and the coil-shaped conductor 2 are, for example, as shown in FIG. 2, A: 1.8 mm, B: 1.0 m.
m, C: 3, 2 mm, D: 2.4 mm, E: 0.7 m
m, F: 4.5 mm, the number of turns of the coil-shaped conductive wire 2 is 7, and the impedance value thereof is 1400 ohms. Corresponding to this, the dimensions of the magnetic core a of the conventional chip-type inductor and the magnetic core portion a1 inside the coil-shaped conducting wire b wound in a circular shape are G: 1.8 mm, H: 3.2.
mm, I: 0.7 mm (minimum jacket size), J: 4.5
mm, and its impedance value is 1400 ohms. According to this example, the height was reduced from 3.2 mm of the conventional one to 2.4 mm, and the height was reduced by 0.8 mm, that is, 25%.

Next, an example of a method for manufacturing the above chip inductor will be described with reference to FIG. The binder S and the magnetic material raw material powder B having an appropriate mixing ratio are kneaded by the kneading machine 5 to homogenize the magnetic material raw material powder and the binding material, and the kneaded kneading material 6 is pressed to the primary extrusion molding machine 7. The rod body 8 having a rectangular cross section as a core having a desired size, which is supplied and formed from the outlet of the primary extruder 7, is extruded at a speed of 30 m / min, for example. This rod body 8 is dried by, for example, a dryer (not shown), and then the conductor wire 10 is wound by a winding machine 9, and the rod body 8 on which the conductor wire 10 is wound is sent to a secondary extrusion molding machine 11. To do. In this secondary extrusion molding machine 11, in advance, the kneading material 6 pressurized and supplied to the primary extrusion molding machine 7 by the kneading machine 5 and the kneading material 12 in which the mixing ratio of the magnetic material powder and the binder is the same or large. Since pressure is applied, the conductor 10 wound around the rod body 8 is covered with the kneading material 12 by the molding machine 11 to form the jacket. After this, cutting is performed according to the size of the firing furnace or the shape of the setter to be laid, and the temperature is 600 to 1000 ° C., for example, 9 ° C.
Bake at 00 ° C. and cut with a cutter according to the size of each inductor. Individual inductor body 13 cut
Is barrel-polished with barrel powder and water, and the corners are rounded. Next, a silver paste composed of silver powder and a solvent is applied to both end faces of the inductor body 13 and the end portions of the outer peripheral surface continuous with the same, and baked to form the external electrodes 3. At this time, the terminals 2a, 2a of the coil-shaped conductor 2 exposed on both end surfaces of the inductor body 13 are connected to the external electrode 3. The silver layer of the external electrode 3 is nickel plated and solder plated. In addition to this manufacturing method, a conductor wire is wound around a fired magnetic rod having a rectangular cross section, and then the outer periphery thereof is coated with the kneading material by an extrusion molding machine to form a jacket,
The inductor body 13 may be formed by firing this in a firing furnace and then cutting it according to the size of each inductor.

FIG. 4 shows another embodiment of the present invention. This chip-type inductor has a coil-shaped conductive wire 2 in which a conductive wire is wound in an elliptical shape inside a magnetic core 1 having a rectangular parallelepiped shape, which can also be manufactured by the manufacturing method shown in FIG. Also in this case, since the coil-shaped conductive wire is formed flat, the height becomes lower than that of the conventional one.

[0011]

The present invention has an effect that the height can be formed lower than that of the conventional chip-type inductor in the above-mentioned structure.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of the present invention.

FIG. 2A and FIG. 2B are explanatory views for explaining the dimensions of the present invention and the conventional chip inductor.

FIG. 3 is an explanatory view showing an example of a method for manufacturing the chip inductor shown in FIG.

FIG. 4 is a perspective view of another embodiment of the present invention.

FIG. 5 is a perspective view of a conventional chip inductor.

[Explanation of symbols]

 1 magnetic core 2 coiled wire 3 external electrode

Claims (2)

[Claims] 1. A chip-type inductor in which a coil-shaped conductor is embedded in a rectangular parallelepiped magnetic core, wherein the coil-shaped conductor is wound in a square shape. 2. A chip-type inductor in which a coil-shaped conductive wire is embedded in a rectangular parallelepiped magnetic core, wherein the coil-shaped conductive wire is wound in an elliptical shape.