JPH0632655Y2 - Structure of bead inductor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bead inductor structure.

A so-called bead inductor is generally used in order to reduce electromagnetic mutual interference generated in a digital circuit and an analog circuit. At a high frequency of 1 MHz or higher, a bead inductor using a ferrite bead core (hereinafter referred to as a ferrite bead inductor) is effective in reducing electromagnetic mutual interference.

Here, the structure of a conventional bead inductor, particularly a ferrite bead inductor, will be described with reference to FIG.

A through hole is provided in the central axis of the cylindrical ferrite core 1, and the conductor wire 2 is passed through this through hole. The conductor wire 2 may be penetrated as shown in FIG. 1 (a), or may be wound one or more times as shown in FIG. 1 (b). The adhesive 3 is injected into the through hole until it reaches both ends of the core.

In the above-mentioned structure, it is difficult to inject an appropriate amount of the adhesive first, the adhesive may adhere to the outer peripheral surface of the core, and there is a problem that it takes a long time to cure the adhesive. . Furthermore, in the above-mentioned inductor, the core may be broken when an external force is applied to the conducting wire or the like.
Further, since it is difficult to dispose this inductor on the substrate in a stable manner, when an external force such as vibration is applied, the core is likely to be chipped or cracked, and the conductor wire may be cut due to fatigue.

An object of the present invention is to provide a bead inductor which is not chipped or cracked in the core and is easy to mount on the substrate.

According to the present invention, it is possible to obtain a bead inductor having a structure in which a thermoplastic or thermosetting resin layer is integrally formed on a bead inductor and the surface of the resin layer is formed to have a flat portion.

Hereinafter, the present invention will be described with reference to the embodiments shown in the drawings. The ferrite bead inductor will be described here, but the same applies to other bead inductors.

First, referring to FIG. 2, which is an embodiment of the present invention, a lead wire 2 is inserted into a through hole of a cylindrical ferrite core 1 having a through hole in its central axis to form a ferrite bead inductor. This ferrite bead inductor has a mold part made of thermoplastic (for example, polyester resin) or thermosetting resin, and the resin layer of the mold part 4 covers the entire surface of the ferrite core 1. Furthermore, the mold part 4 in this example has a hexagonal cross-sectional shape.

The illustrated ferrite bead inductor can be manufactured by positioning the lead wire 1 in the ferrite core 1 in a hexagonal prism-shaped mold and injecting, for example, polyester resin into the mold.

In the ferrite bead inductor having the above-described structure, since the ferrite core 1 is sealed by the mold portion 4, damage to the ferrite core 1 due to external force such as vibration can be prevented, and the surface shape is hexagonal columnar using resin. Therefore, the ferrite bead inductor can be stably arranged on the circuit board by bringing one flat surface of the hexagonal column into contact with the circuit board.

Further, as described above, since the mold portion 4 is integrated with the ferrite core 1 by using the mold, the work of bonding the ferrite core 1 and the conductor wire 2 is not necessary, and the solidification can be achieved in a short time.

In addition, in the embodiment shown in FIG. 2, the surface shape is a hexagonal column, but as shown in FIG. 3, a flat portion 5 extending along the central axis is formed in a part of the outer periphery as the mold portion 4. You may use what has.

In other words, it suffices to form a flat portion on the surface of the resin layer so that the ferrite bead inductor can come into contact with the circuit board.

Further, as shown in FIG. 4, in the resin layer forming operation, a plurality of ferrite bead inductors may be molded at once. In this case, the ferrite bead inductors are connected to each other by the thin portion 6, and the ferrite bead inductor can be mounted on the circuit board as it is, or can be separated by the thin portion 6.

In addition, when connecting the ferrite bead inductors with a thin portion as described above, if each ferrite bead inductor has a hexagonal column shape, the strength of the die is higher than that of the square column shape or the shape shown in FIG. Is strong, and the life of the mold can be extended. In this embodiment, the case of using the ferrite bead core has been described, but the same effect can be obtained with other bead cores.

As described above, according to the present invention, a bead inductor, particularly a ferrite bead inductor, is molded with a thermoplastic resin or a thermosetting resin, and a flat surface portion that comes into contact with a circuit board is provided on the surface of the resin layer to form an integrated body. Since the structure is formed, it is possible to provide a bead inductor that is not damaged by external force such as vibration, has high environmental resistance, is easy to manufacture, and is inexpensive.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of the structure of a conventional ferrite bead inductor, FIG. 2 is a perspective view showing one embodiment of the present invention, and FIG. 3 is a perspective view showing another embodiment of the present invention. FIG. 4 is a front view showing still another embodiment according to the present invention. DESCRIPTION OF SYMBOLS 1 ... Ferrite core, 2 ... Conductive wire, 3 ... Adhesive agent, 4 ... Mold part, 5 ... Plane part, 6 ... Thin part.

Claims (1)

[Scope of utility model registration request] 1. A bead inductor having a core having a through hole and a conductive wire, wherein the conductive wire is inserted into the through hole in the previous stage, the core including the conductive wire being a thermoplastic or thermosetting resin. The structure of the bead inductor is characterized in that a flat portion is formed on the molding surface, the flat portion being in contact with the circuit board.