JP2005142459A - Surface mount type inductor - Google Patents

Abstract

An object of the present invention is to provide a surface mount type inductor in which a winding terminal is joined to a joining electrode without being bent and the reliability of fixing a core is improved.
In a surface mount type inductor in which two naveled pot cores and an air-core coil are housed, the naveled pot core has a magnetic core serving as a winding core inside, and terminals on a pair of opposing end surfaces on the upper surface. A pair of opposed notches are provided in the engaging recess and the bottom of the side. The air-core coil is wound with an insulation-coated conductor having a fusion layer on the surface, and the winding start and end terminals are drawn out to the outer periphery of the winding-so-called α winding. A connection that has a U-shaped cross-section, is provided with springiness, and has a connection terminal that sandwiches the terminal engagement recesses of two combined navel pot cores, and extends from the center of one end of the connection terminal It has a department.
[Selection] Figure 1

Description

The present invention relates to a surface mount type (SMD) inductor.

  In recent years, with the increase in portable electronic devices such as mobile communication devices, there has been a demand for low loss and high efficiency of electronic components and circuits. In particular, many attempts have been made to reduce the heat generated by the resistance due to the high-frequency loss and the current as much as possible in the coil for switching power supply due to the higher frequency accompanying the downsizing.

As an example, Patent Document 1 discloses a switching method in which a rectangular wire is wound in a spiral shape to increase the space factor of the winding, and the DC resistance Rdc of the winding is reduced as much as possible to reduce the loss due to current. A power SMD choke coil is described.
By the way, in the SMD choke coil using this flat wire, the winding method is a spiral winding wound from the inside to the outside. Therefore, the winding start terminal of the winding must be drawn out from the inside to the outside and connected to the external connection terminal, which is complicated in order to have a structure in consideration of contact with the winding. In addition, it is necessary to devise a method for pulling out the winding terminal.

On the other hand, Patent Document 2 describes a coil using so-called α winding in which winding ends at the beginning and end of winding are led to the outer periphery as windings using a rectangular wire.
FIG. 4 shows an exploded perspective view of the coil.
As shown in FIG. 4, the coil 20 has an air core coil 23, an outer core 21 provided with a cylindrical coil housing part b having a concave cross section, and a cross section including a flange part 22 a at one end of the core part a. The structure is a T-shaped core 22.

  The outer core 21 forms a U-shaped terminal electrode 24. Both ends 23a, 23b are joined to the joint 24a of the terminal electrode 24 by thermocompression bonding, arc welding, soldering or the like while the air-core coil 23 is installed in the coil housing part b of the outer core 21. The core part a of the T-shaped core 22 is inserted into the center hole of the air-core coil 23, and the T-shaped core 22 and the outer core 21 are bonded and fixed with an adhesive such as an epoxy adhesive.

In this structure, in order to connect the both ends 23a, 23b of the air-core coil 23 to the terminal electrode 24, it is necessary to bend the flat wire at the start of winding, the end of winding and the portion 24a to be joined (bending portion 25). . For this reason, the bent portion of the rectangular wire damages the insulating film, and there is a problem in reliability such as heat generation and short circuit when a large current flows.
JP 7-288210 A JP 2002-170729 A

  The present invention has been made in view of such a background, and an object of the present invention is to provide a surface-mount type inductor that is bonded to a bonding electrode without bending a winding terminal and that has improved core fixing reliability. And

  In order to solve the above-mentioned problems, the present invention provides two naveled pot cores and a surface mount type inductor in which an air core coil is housed, and the navel pot core includes a magnetic core serving as a winding core inside. A pair of opposed end faces on the upper surface are provided with a terminal engaging recess, and a pair of opposed notches are provided on the side skirt. The air-core coil is wound with an insulation-coated conductor having a fusion layer on the surface, and the winding start and end terminals are drawn out to the outer periphery of the winding-so-called α winding. A connection that has a U-shaped cross-section, is provided with springiness, and has a connection terminal that sandwiches the terminal engagement recesses of two combined navel pot cores, and extends from the center of one end of the connection terminal It has a department.

  As described above, the present invention provides an air core coil wound with an insulation-coated conductive wire having a fusion layer on the surface thereof, and a winding in which the winding start and winding end terminals are drawn to the outer periphery of the winding. (So-called α winding), so that the combined two navel pot cores can be sandwiched, and the joint terminal provided with a connection part for connecting the coil terminal can be pulled out without being bent and connected to the joint terminal . Since there is no work to bend the winding terminal, the winding terminal is not damaged, and therefore, no heat generation or short circuit occurs. In addition, since the two pot cores are sandwiched and fixed by the joining terminals, it is possible to provide a highly reliable surface-mount inductor that is resistant to drop impact.

An embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a perspective view of a surface mount inductor according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of the surface mount inductor shown in FIG.

As shown in FIG. 1 and FIG. 2, in the surface mount type inductor 10 of the present invention, 1 and 2 are naveled pot cores, 3 is an air core coil, and 4 is a structure of a junction terminal.
The air-core coil 3 has two layers of winding start and winding end terminals 3a and 3b drawn out to the outer periphery using a rectangular wire which is an insulation coated conductor having a wide cross section with a fusion layer on the surface. A so-called α winding.
The naveled pot cores 1 and 2 are made of a ferrite magnetic material formed into a substantially square shape and fired. A coil housing portion b having a concave cross section is provided, and a magnetic leg (navel) through which the center hole of the air core coil 3 is inserted at the center of the inside E-shaped core provided with a. Terminal engagement recesses c <b> 1 and c <b> 2 that engage the joining terminals 4 are provided on a pair of opposing end surfaces on the upper surface of the core. Further, a pair of opposed notches b1 and b2 for drawing out the winding terminals 3a and 3b of the air-core coil 3 are provided at the skirts on the side surfaces adjacent to each other.

  The junction terminal 4 is a conductive metal terminal and has a U-shaped cross section, and a junction surface 4a and a junction surface extending from one end of the central portion in the direction of the notch. Protrusions 4b projecting at right angles in the outward direction are provided at both ends. The joint terminal 4 is for fitting the winding terminals 3a and 3b of the air-core coil 3 to the joint surfaces 4a and 4a, and bending and holding the protrusion 4b.

Next, a manufacturing method will be described.
An air-core coil 3 that is pre-wound around the magnetic leg a of one navel pot core 2 (or 1) by applying an epoxy adhesive to the tip of each magnetic leg a of the two navel pot cores 1 and 2. Is inserted into the magnetic leg a, and the winding terminals 3a and 3b of the air-core coil 3 are passed through the notches b1 and b2 of the respective cores. Next, the leg portion a of the other navel-attached pot core 1 (or 2) is passed through the center of the air-core coil, and the two navel-attached pot cores 1 and 2 and the air-core coil 3 are combined. Simultaneously, the two joining terminals 4 are engaged and clamped in the terminal engaging recesses c1 and c2 of the navel pot cores 1 and 2, respectively. Then, an epoxy adhesive 8 having heat resistance is applied between the joining terminal 4, the terminal engaging recesses c1 and c2, and the terminal engaging recess to adhere and fix. However, the adhesive is not allowed to adhere to the outer periphery of the junction terminal. Next, the winding terminals 3a and 3b of the air-core coil 3 are cut to a length matching the joining surface 4a of the joining terminal 4 (may be cut to a preset length), and the protrusion 4b is bent inward. Hold the winding terminal. And winding terminal 3a, 3b and the junction terminal 4 are electrically connected by soldering or thermocompression bonding, welding, etc. in a bending part.

  As described above, the surface mount type inductive coil of the present invention forms the air core coil with the α winding and draws the winding terminal from the outer periphery so that the winding terminal of the flat wire is led to the joining terminal without being bent. No damage to the flat wire. And it is possible to mechanically and electrically connect the wound winding terminal while sandwiching the two pot cores using the joining terminal. And it can fix firmly using a heat resistant resin adhesive between the terminal engagement recessed part of the two navel pot cores combined with the joining terminal, and a terminal engagement recessed part. This makes it possible to provide a surface mount inductor that is resistant to drop impact.

FIG. 3 is a perspective view of an air-core coil using insulating film conductors having different cross-sectional shapes as another embodiment.
FIG. 3A is a rectangular wire having a width n wider than a thickness m of the insulating coating wire used in the above embodiment. It is suitable mainly for narrower width than thickness and smaller mounting area.
FIG. 3B is an air-core coil using an insulating film conductor in which the thickness m is thicker than the width n contrary to FIG. 3A, and is suitable for a surface-mount type inductor having a suppressed height.
FIG. 3 (c) is an insulating film conductor having a round (circle) cross section used for winding of a general coil, and the price is lower than that used in FIGS. 3 (a) and 3 (b). Winding work is easy and economical, so it is suitable for surface mount type inductors considering the economy.
3A, 3B, and 3C may be selected in consideration of characteristics, workability, economy, and the like.

  As mentioned above, although the Example of the surface mount type inductor of this invention was described, it is not restricted to these Examples. For example, in the embodiment, the two-layer winding is used. However, when the inductance is large and the number of turns is to be increased, a multilayer winding may be used. The two navel-attached pot cores have an E-shaped square cross section, but may be round or polygonal, and the air-core coil storage portion may be cylindrical. Moreover, you may combine a thing with a cross section of E shape, and a I shape. About a junction terminal, not only the shape of an Example but the shape which can electrically connect a coil | winding terminal and can clamp two navel pot cores should just be sufficient.

1 is a perspective view of a surface mount inductor according to an embodiment of the present invention. FIG. 2 is an assembled perspective view of the surface mount inductor according to the embodiment of the present invention shown in FIG. Perspective view of air-core coil using insulating coating conductors with different cross-sectional shapes Assembly perspective view of coil using conventional rectangular wire

Explanation of symbols

1, 2 Naveled pot core 3 Air core coil 4 Connection terminal b1, b2 Notch c1, c2 Terminal engagement recess

Claims (5)

In surface mount type inductors that house two navel pot cores and air core coils inside,
The naveled pot core has a magnetic core serving as a winding core inside, a pair of opposing end faces on the upper surface are provided with terminal engaging recesses, and a pair of opposed notches are provided on the side skirts,
The air-core coil is wound with an insulation-coated conductor having a fusion layer on the surface, and the winding start and end of winding are drawn out to the outer periphery of the winding-so-called α winding,
A connection that has a U-shaped cross section, is provided with springiness, and has a connection terminal that sandwiches the terminal engagement recesses of the two combined pot cores, and extends from the center of one end of the connection terminal A surface-mount type inductor characterized by comprising a portion. In surface mount type inductors that house two navel pot cores and air core coils inside,
The naveled pot core has a magnetic core serving as a winding core inside, a pair of opposing end faces on the upper surface are provided with terminal engaging recesses, and a pair of opposed notches are provided on the side skirts,
The air-core coil has a fusion layer on its surface and is wound using a rectangular wire, which is a rectangular insulation-coated conductor having a wide cross section, and ends of winding start and end of winding are on the outer periphery of the winding. Pulled out-the so-called alpha roll,
A connection that has a U-shaped cross section, is provided with springiness, and has a connection terminal that sandwiches the terminal engagement recesses of the two combined pot cores, and extends from the center of one end of the connection terminal A surface-mount type inductor characterized by comprising a portion. In surface mount type inductors that house two navel pot cores and air core coils inside,
The navel-attached pot core has a rectangular plane, and has a magnetic core serving as a winding core inside. The pair of opposed end faces on the upper surface have terminal engaging recesses and a pair of cut faces facing the skirts of the side surfaces adjacent to each other. There is a notch,
The air-core coil has a fusion layer on its surface and is wound using a rectangular wire, which is a rectangular insulation-coated conductor having a wide cross section, and ends of winding start and end of winding are on the outer periphery of the winding. Pulled out-the so-called alpha roll,
A connection that has a U-shaped cross section, is provided with springiness, and has a connection terminal that sandwiches the terminal engagement recesses of the two combined pot cores, and extends from the center of one end of the connection terminal A surface-mount type inductor characterized by comprising a portion. 4. The surface mount inductor according to claim 1, wherein the connection terminal includes protrusions on both end faces in the width direction of the connection portion. 5. The surface mount inductor according to claim 1, wherein a thermosetting resin adhesive is applied and fixed along a side surface from the connection terminal, the terminal engagement recess, and the terminal engagement recess.

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