JP2003243228A - Common mode filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a common mode filter which is improved in reliability by connecting a pair of coil windings between terminals in a jointless constitution and reduced in height by winding a flat type electric wire in an edgewise winding structure. <P>SOLUTION: A pair of flat type electric wires 11 and 12 which are coated for insulation are laminated in the direction of thickness, widthwise curved, and cylindrically coiled into coil windings 10 and 20 that are connected together. The insulating coating is separated from the ends of the coil windings 10 and 20, the bare ends of the coil winding 10 and 20 are bent so as to serve as surface mounting terminals 12 and 22, the coil windings 10 and 20 are housed in a magnetic core structure 30 which is equipped with a center leg that is inserted into the inner circumferences of the coil windings 10 and 20 and covers the periphery of the coil windings 10 and 20, a cutout 51 is provided to each corner of the bottom of the magnetic core structure 30, and the surface mounting terminals 12 and 22 are made face to the cutouts 51 and kept exposed. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a common mode filter for removing common mode noise by inserting it into a DC line of a portable personal computer, a small electronic device or the like.

[0002]

2. Description of the Related Art Conventionally, as a common mode filter of this type, as shown in FIG. 3, a pair of coil windings 1 are formed by bifilarly winding a wire having a general circular cross section, which is formed with a pot core 2 and a flat plate. It is known to be housed in a magnetic core structure consisting of the core 3. In this case, the terminal structure is such that the terminal electrode 4 is formed on the bottom surface of the flat core 3 by a printing and baking layer of silver paste and an electroplating layer of copper, nickel and tin formed thereon, The winding end 6 of the coil winding 1 is inserted into the formed hole 5 and soldered (dip soldering) to the terminal electrode 4.

[0003]

By the way, in recent years, lead-free solder may be used for mounting a common mode filter on a wiring board. However, since lead-free solder has a higher melting point than eutectic solder, There is also a problem that the solder connection portion P with the winding terminal 6 is also melted and the reliability of the connection between the two is reduced. Further, a pair of coil windings 1 is manufactured by bifilar winding a wire having a general circular cross section, and a step of forming the terminal electrode 4 on the flat core 3 and a step of connecting the winding terminal 6 to the terminal electrode 4. Are required, the number of manufacturing processes is large, and it is difficult to reduce the height.

In view of the above points, the present invention improves reliability by forming a wireless connection between a pair of coil windings and terminals, and stacks rectangular electric wires in the thickness direction and in the width direction. It is an object of the present invention to provide a common mode filter capable of achieving a low profile by forming an edgewise winding structure that is bent into a curved shape and wound into a tubular shape.

Other objects and novel features of the present invention will be clarified in the embodiments described later.

[0006]

In order to achieve the above object, a common mode filter according to the invention of claim 1 of the present application comprises a pair of insulating coated rectangular electric wires laminated in a thickness direction and curved in a width direction. Bend into a cylindrical shape and form a pair of coil windings that are connected to each other by winding in a tubular shape, remove the insulating coating from the winding ends of each coil winding, and bend the winding ends And having the pair of coil windings housed in a magnetic core structure that has a central leg portion that is inserted into the inner circumferences of the pair of coil windings and that covers the periphery of the pair of coil windings, A notch is formed in the bottom surface of the magnetic core structure, and the surface mount terminal is exposed by exposing the surface mount terminal to the notch.

A common mode filter according to a second aspect of the present invention is the common mode filter according to the first aspect, characterized in that the surface mount terminal portion is bent so as not to protrude to the side of the magnetic core structure. .

A common mode filter according to a third aspect of the present invention is the common mode filter according to the first or second aspect, wherein the surface mount terminal portion is formed by bending the winding terminal in a U shape and inwardly. The inside of the U-shaped bent portion is a space.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a common mode filter according to the present invention will be described below with reference to the drawings.

1 and 2 show an embodiment of a common mode filter according to the present invention. In these figures, 1
Reference numerals 0 and 20 denote a pair of coil windings, which are used by stacking insulated flat electric wires 11 and 21 such as enameled wires, and stacking the flat electric wires 11 and 21 in the thickness direction and curving in the width direction. The coil windings 10 and 20 have the same number of turns and are tightly coupled to each other. The winding ends 10a and 20a of the coil windings 10 and 20 have their insulating coatings peeled off, and the insulating coating peeled portions S are tin-plated. Also,
The winding terminals 10a and 20a are bent in a U shape to form the surface mount terminal portions 12 and 22.

On the other hand, as shown in FIG. 2, the magnetic core structure 30 includes a central leg portion 41 which is inserted into the inner circumference of the pair of coil windings 10 and 20 and the periphery (upper surface) of the pair of coil windings. And a ferrite pot core 40 having an outer shell portion 42 covering four side surfaces) and a ferrite flat core 50 (bottom portion of the magnetic core structure) forming a closed magnetic circuit by closing the bottom side opening of the pot core 40. Become. Magnetic core structure 3
Notch portions 51 for exposing the surface mounting terminal portions 12 and 22 at the four corners of the flat core 50 which is the bottom portion of 0.
Are formed.

Then, after the pair of coil windings 10 and 20 are housed in the pot core 40, the flat core 50 is bonded to the bottom side of the pot core 40 by using an adhesive or the like.
From the cutout 51 of the flat core 50 to the surface mount terminal 12,
It is possible to obtain a common mode filter in which 22 is exposed and which has a structure that is flush with the bottom surface of the flat plate-like core 50 or that projects slightly downward. At this time, the surface mount terminal portion 12,
Reference numeral 22 denotes winding ends 10a and 20a which are bent in a U shape and formed inward, do not protrude to the side of the magnetic core structure 30, and the inside of the bent portion is a flat plate. It is a space where the core 50 does not enter.

According to this embodiment, the following effects can be obtained.

(1) Winding ends, that is, rectangular electric wires 11 and 2.
Since the surface mount terminal portions 12 and 22 are directly formed by bending the end portion of 1, there is no connecting wire portion, which is highly reliable,
The common mode filter can be mounted on the wiring board with lead-free solder without any trouble. In addition, a terminal component as a separate component or a terminal electrode formed on the surface of the core is not required, and cost can be reduced.

(2) A pair of coil windings 10, 20 are formed as edgewise windings by laminating a pair of flat rectangular electric wires 11, 21 in the thickness direction and bending them in a widthwise direction. It is possible to achieve a lower profile than a bifilar winding wire having a circular cross section. In addition, the degree of coupling between the pair of coil windings 10 and 20 can be increased.

(3) The surface-mounting terminal portions 12 and 22 are formed by bending the winding terminals 10a and 20a in a U-shape, and there is no core or substrate on the upper surface side of the surface-mounting terminal portions 12 and 22. This is a space, and when soldering to the wiring board, the solder can also go around to the upper side of the surface mount terminal portions 12 and 22, so that the soldering can be reliably performed. Further, by bending the surface-mounting terminal portions 12 and 22 inwardly and inwardly, the surface-mounting terminal portions 12 and 22 do not protrude to the side of the magnetic core structure 30 and the mounting area can be reduced.

Although the embodiment of the present invention has been described above, it is obvious to those skilled in the art that the present invention is not limited to this and various modifications and changes can be made within the scope of the claims. Ah

[0018]

As described above, according to the common mode filter of the present invention, the connection between the pair of coil windings and the surface mount terminal portion is not connected to improve reliability. It is possible to reduce the height by forming the edgewise winding structure in which the rectangular electric wires are laminated in the thickness direction and bent in the width direction in a curved shape to be wound in a tubular shape.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing an embodiment of a common mode filter according to the present invention.

FIG. 2 is a side sectional view of the same.

FIG. 3 is a side sectional view showing an example of a conventional common mode filter.

[Explanation of symbols]

10, 20 coil winding 10a, 20a Winding terminal 11,21 flat wire 12,22 Surface mount terminal 30 Magnetic core structure 40 pot core 41 Central leg 50 flat core 51 Notch

Claims (3)

[Claims] 1. A pair of insulation-coated rectangular electric wires are laminated in a thickness direction, bent in a width direction to be curved and wound into a tubular shape to form a pair of coil windings, which are coupled to each other. The insulating coating on the winding end of the coil winding is peeled off, the winding end is bent to form a surface mount terminal portion, and the central winding portion is inserted into the inner periphery of the pair of coil windings, and The pair of coil windings are housed in a magnetic core structure that covers the periphery of the pair of coil windings, and a cutout portion is formed in the bottom surface of the magnetic core structure, and the surface mount terminal portion is formed in the cutout portion. A common mode filter characterized in that the surface mount terminal portion is exposed to face it. 2. The common mode filter according to claim 1, wherein the surface mount terminal portion is bent so as not to protrude laterally of the magnetic core structure. 3. The surface mount terminal portion is formed by bending the winding end into a U-shape and is formed inward, and the inside of the U-shape bent portion is a space. The common mode filter according to 1 or 2.