JPH0689824A - Choke coil - Google Patents

Abstract

PURPOSE:To increase inductance by reducing magnetic reluctance and leakage magnetic flux. CONSTITUTION:A solid columnar inside core 13 of a ferromagnetic body is closely fit in an empty core of a coil 12. A hollow columnar outside core 14 formed of a ferromagnetic body is closely fit to an outer peripheral surface of the coil 12. After nickel platings 15a, 15b are applied approximately all over both ends in an axial direction thereof, a pair of electrodes 16a, 16b are formed by solder plating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mounting choke coil suitable for mounting on a hybrid integrated circuit.
The present invention relates to a choke coil whose inductance is increased.

[0002]

2. Description of the Related Art Conventionally, this type of chip type RFC (Radio
As an example of a cylindrical choke coil such as a frequency choke, the one shown in the vertical sectional view of FIG. 4 is known. In this, an inner core 2 made of a ferromagnetic material (or a melf type resistor) is inserted inside (air core) of a winding coil 1 in which a coated conductive wire is wound in a solenoid shape.

Then, the insulating coatings on both axial ends of the winding coil 1 are removed, and the removed portion and both axial ends of the inner core 2 are subjected to a base treatment of nickel plating 3a, 3b and then solder-plated. The electrodes 4a and 4b are formed and fixed.

[0004]

However, in such a conventional choke coil, since the outer peripheral surface of the winding coil 1 is exposed to the outside air, the magnetic flux passing through the outside of the winding coil 1 has a large magnetic resistance. Pass through the open air. For this reason, there is a problem that the magnetic resistance becomes large, the leakage magnetic flux becomes large, and the inductance becomes small.

Therefore, the present invention has been made in consideration of such circumstances, and an object thereof is to provide a choke coil having a large inductance by reducing the magnetic flux leaking to the outside of the winding coil.

[0006]

The present invention is configured as follows in order to solve the above-mentioned problems.

That is, according to the present invention, a winding coil formed by winding a conductor wire in a solenoid shape, an inner core made of a magnetic material inserted inside the winding coil, and both axial ends of the inner core and the winding coil are provided. In a choke coil having a pair of electrodes fixed to and electrically connected to a surface, an outer core made of a magnetic material is provided to cover an outer peripheral surface of the winding coil.

[0008]

[Function] Since the magnetic flux passing through the inside of the winding coil passes through the inner core made of a magnetic material having a small magnetic resistance, and the magnetic flux passing through the outside of the winding coil also passes through the outer core made of a magnetic material having a small magnetic resistance, Both the magnetic resistance and the leakage magnetic flux can be reduced to increase the inductance.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention, FIG.
Is a perspective view showing a manufacturing method thereof. In the figure, the choke coil 11 first forms a winding coil 12 by winding a coated conductive wire in a solenoid shape, and an insulating coating is removed on substantially the entire axial ends thereof. The bare portions 12a and 12b are formed.

Next, the inside of this winding coil 12 (air core)
Then, the solid cylindrical inner core 13 made of a ferromagnetic material is closely inserted.

On the other hand, outside the winding coil 12, ferrite, amorphous magnetic material, melf type resistor, YIG
A hollow columnar outer core 14 made of a ferromagnetic material such as (yttrium, iron, garnet) is tightly fitted.

Next, the winding coil 12 and the inner and outer cores 1
Substantially all the axial end portions of 3, 14 are subjected to a base treatment such as nickel plating 15a, 15b to facilitate solder plating, and then solder plating is performed to form a pair of left and right electrodes 16a, 16b. There is.

Therefore, according to the choke coil 11, the magnetic flux inside the winding coil 12 passes through the inner core 13 made of a ferromagnetic material having a low magnetic resistance and the winding coil 1
The magnetic flux on the outer side of 2 also passes through the inside of the outer core 14 having a lower magnetic resistance than in the air, so the magnetic resistance and the leakage magnetic flux can be reduced, and as a result, the inductance can be increased.

In the above-mentioned embodiment, the case where the outer core 14 is formed in a cylindrical shape has been described, but the present invention is not limited to this. For example, a rectangular cylindrical outer core 14a shown in FIG. The outer shape may be formed in a rectangular shape. The rectangular cylindrical outer core 14a has substantially the same electrical characteristics as the cylindrical outer core 14, but has the advantages that it is hard to roll and that the outer flat surface is easily marked, and the mounting work is simplified. be able to.

[0016]

As described above, according to the present invention, since the outer peripheral surface of the winding coil is covered with the outer core made of a magnetic material,
Since the magnetic flux passing through the outside of the winding coil passes through the outer core made of a magnetic material having a magnetic resistance lower than that in the air, both the magnetic resistance and the leakage magnetic flux can be reduced and the inductance can be increased.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an embodiment of a choke coil according to the present invention.

FIG. 2 is a perspective view showing a manufacturing method of the embodiment shown in FIG.

FIG. 3 is a perspective view showing a modified example of the outer core shown in FIG.

FIG. 4 is a vertical sectional view of a conventional choke coil.

[Explanation of symbols]

 11 choke coil 12 winding coil 13 inner core 14 outer core 14a square tubular outer core 15a, 15b nickel plating 16a, 16b pair of electrodes

Claims (1)

[Claims] 1. A winding coil formed by winding a conductor wire in a solenoid shape, an inner core made of a magnetic material inserted into the inside of the winding coil, and fixed to the inner core and both end surfaces in the axial direction of the winding coil. A choke coil having a pair of electrodes that are electrically connected to each other, wherein an outer core made of a magnetic material that covers an outer peripheral surface of the winding coil is provided.