JPH08148341A - Chip inductor - Google Patents

Abstract

PURPOSE: To obtain a chip inductor in which a predetermined inductance can be attained without causing any loosening or disordering of winding by employing a prism core part. CONSTITUTION: The chip inductor 1 comprises a core 2 made of a magnetic material, e.g. ferrite. The core 2 comprises a quadrangular prism core part 3 having rectangular cross-section, and quadrangular fringe parts 4 projecting in flange-shape from the sides facing the core part 3 at the opposite ends in the axial direction thereof substantially normally therefrom. The chip inductor 1 has substantially H-shaped plan view. A conductive part 5 is provided on the side face at the fringe part 4 of the core 2 which is coplanar with the core part 3. The core 2 is connected electrically and mechanically, at the conductive part 5 thereof, with one end of a planar elongated electrode piece 10 made of a metal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip inductor in which a core around which a coil is wound is provided with a pair of electrode pieces to which both ends of the coil are connected.

[0002]

2. Description of the Related Art Conventionally, as a chip inductor of this type, for example, a structure described in Japanese Patent Laid-Open No. 2-50404 is known.

The chip inductor described in Japanese Patent Application Laid-Open No. 2-50404 has a pair of leads in which both ends of a coil wound around a winding core of a drum core are axially projected from both end surfaces of the drum core. It connects to each terminal and covers the coil with a protective layer. Further, the lead terminals are engaged with the engaging portions provided on the upper ends at a position spaced apart from the both end surfaces of the drum-shaped core by the rising portions of the pair of electrode pieces which are raised so as to face the both end surfaces of the drum-shaped core. The drum-shaped core is electrically and mechanically connected to the coil-shaped core, the lead terminal and the rising portion of the electrode piece are integrally molded with the molded body.

[0004]

However, in the chip inductor described in the above-mentioned Japanese Patent Laid-Open No. 2-50404, since the drum-shaped core has a circular cross section, winding slack or loosening occurs when winding the coil. There is a possibility that it will occur, and the prescribed inductance cannot be obtained.

Further, since the rising portion of the electrode piece faces the end surface of the drum-shaped core, the magnetic flux generated when the coil is energized intersects with the rising portion, which causes a problem that the Q value is lowered.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a chip inductor which can stably obtain predetermined characteristics.

[0007]

According to a first aspect of the present invention, there is provided a chip inductor, a coil, a winding core portion around which the coil is wound, and both ends of the winding core portion in the axial direction around which the coil is wound. A core provided with a flange-shaped projecting edge portion, a pair of electrode pieces provided at both ends of the core and connected to both ends of the coil, a core on which the coil is wound, and the pair of electrodes. In a chip inductor including a mold body in which a part of an electrode piece is integrally embedded, a winding core portion of the core has a prismatic shape.

A chip inductor according to a second aspect of the present invention is the chip inductor according to the first aspect, wherein the winding core portion is formed in a quadrangular prism shape, and the projecting edge portions are directed outward at a pair of opposite sides of the winding core portion. It is formed in a protruding rectangular column shape.

According to a third aspect of the present invention, there is provided a chip inductor according to the first or second aspect, wherein a pair of electrode pieces is connected to one side surface of the projecting edge portion, and both ends of the coil are connected to the side surface. Is provided with a conductive part.

[0010]

In the chip inductor according to the first aspect of the present invention, since the winding core of the core around which the coil is wound is formed in a prismatic shape, the coil is wound without loosening or winding slack, and a predetermined characteristic can be stably obtained. .

According to a second aspect of the present invention, in the chip inductor according to the first aspect, the core is provided by projecting outwardly at a pair of opposite sides of a square columnar winding core portion and providing a square columnar projecting edge portion. Since the coil is formed, the coil is wound without loosening or winding slack, the predetermined characteristics are stably obtained, the ratio of the surface area to the volume of the core is reduced, and the core due to the stress generated when the mold body is hardened is added to the core. The strain to be received is reduced, the decrease in magnetic permeability is prevented, and the predetermined characteristics are stably obtained easily.

A chip inductor according to a third aspect is the chip inductor according to the first or second aspect, wherein both ends of the coil are connected to one side surface of the projecting edge portion of the core, and a pair of electrode pieces are connected to each side. Since the pair of conductive portions is provided, the amount of magnetic flux that intersects the electrode piece when the coil is energized is reduced, and the Q value is prevented from being lowered.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of one embodiment of the chip inductor of the present invention will be described below with reference to the drawings.

1 and 2, reference numeral 1 denotes a chip inductor, which has a core 2 formed of a magnetic material such as ferrite. This core 2 has a rectangular columnar winding core portion 3 having a rectangular cross section, and a rectangular columnar projecting edge portion 4 projecting substantially vertically from both sides in the axial direction of the winding core portion 3 in a direction of a flange in a substantially vertical manner. From plane H
It is shaped like a square shape. In addition, the projecting edge portion 4 of the core 2
Conductive portions 5 made of a conductive material are provided on the side surfaces that are flush with the winding core portion 3.

In the chip inductor 1, a conductive wire 7 such as a polyurethane-coated electric wire is wound around a winding core portion 3 of a core 2, and both ends thereof are electrically and mechanically connected to the conductive portions 5 and 5, respectively, to form a coil 8. Is wrapped around. Further, on the outer peripheral surface of the coil 8, on the side where the lead wires 7a, 7a of the conductor 7 from the coil 8 connected to the conductive portion 5 are located, polybutadiene for preventing winding looseness or loosening of the coil 8 is used. A protective layer 9 made of synthetic resin is provided.

Further, to the core 2, one end of a metal elongated plate-shaped electrode piece 10 is electrically and mechanically connected to the conductive portion 5, respectively.

The chip inductor 1 includes the coil 8
The core 2 around which is wound and a part of the pair of electrode pieces 10 and 10 are integrally molded with a molding resin to form a molded body.
The electrode piece is embedded in the mold body 11 and extends along the outer peripheral surface of the mold body 11.
Electrodes are formed by bending 10 and 10 in the same direction to form a chip.

The electrode piece 10 is not limited to a simple metal piece, but may be one having a solder layer provided on the outer surface in advance, or the solder layer may be provided on the outer surface after bending.

Next, the manufacturing process of the above embodiment will be described with reference to the drawings.

First, as shown in FIG. 3, a planar substantially H-shaped core 2 having a projecting edge 4 at both axial ends of a winding core 3 is formed in advance from a magnetic material such as ferrite. The side surface that is flush with the winding core portion 3 of the projecting edge portion 4 of the core 2 has
As shown in, a pair of conductive parts 5 is provided by vapor deposition, sputtering, thick film printing, metal foil bonding, or the like.

Then, one end of a conductor wire 7 such as a polyurethane-coated electric wire is electrically and mechanically connected to one conductive portion 5 of the core 2 by thermocompression bonding such as pulse heat, and the conductor wire 7 is wound around the core 2. The core wire 3 is wound a predetermined number of times and the conductor 7
Similarly, the other end of the coil is electrically and mechanically connected to the other conductive part 5, and the coil 8 is attached to the winding core part 3 of the core 2 as shown in FIG.
To wind up.

Next, the core 2 around which the coil 8 is wound is shown in FIG.
As shown in FIG. 5, a pair of conductive parts 5 and 5 to which the lead wires 7a and 7a are connected are mounted on the tips of the metal pieces 13a and 13a between the metal pieces 13a and 13a that project to face the strip-shaped metal frame 13. The core 2 is placed so as to be placed, and the conductive portion 5 and the metal piece 13a are connected by welding or thermocompression bonding. And
As shown in FIG. 7, a protective layer 9 made of synthetic resin such as polybutadiene is provided on the surface of the coil 8 to which the metal piece 13a is attached.

Thereafter, as shown in FIG. 8, the core 2 around which the coil 8 is wound and the tip portions of the pair of metal pieces 13a, 13a are integrally molded with a molding resin into a substantially rectangular parallelepiped, and a cured mold is formed. The outer peripheral surface of the body 11 is appropriately marked.

The metal pieces 13a, 13 of the metal frame 13 are
The base end of a is cut to form the metal piece 13a as the electrode piece 10, and the pair of electrode pieces 10 and 10 protruding from the mold body 11 are bent toward the protective layer 9 side along the outer peripheral surface of the mold body 11. Then, the tips are made to face each other to form electrodes, and the chip inductor 1
To form.

Next, the operation of the above embodiment will be described.

The coil 8 of the chip inductor 1 manufactured according to the above example was energized and the frequency characteristics of the inductance and the Q value were measured. Further, as a comparative example, a chip inductor having a drum-shaped core formed to have the same outer diameter was used. The results are shown in FIG. 9 and FIG.
0 is shown.

From the results of the frequency characteristics shown in FIG. 9, the Q value of the present embodiment is higher than that of the conventional drum type core, and the change ratio of the inductance due to the frequency change is small. It can be seen that stable characteristics can be obtained.

Further, from the results of the DC superposition characteristics shown in FIG. 10, it can be seen that in the present embodiment, the inductance decreases less with the increase in the DC superposition current and the current capacity can be made larger than that of the conventional one.

By the way, it is known that when the conductive wire 7 is wound around the winding core portion 3 of the core 2 and the conductive wire 7 is wound unevenly, a predetermined inductance cannot be obtained.

When the conductor wire is wound around the drum-shaped core having the conventional winding core portion, the conductor wire may not be caught by the outer peripheral surface of the winding core portion, and the conductor wire may be loosened or loosened. However, since the core 2 of this embodiment does not have a predetermined inductance due to the loosening and the winding slack, the core 7 of the core 2 is a quadrangular prism, so that the conductor wire 7 is caught on the corner of the core 3. Since it is wound, it can be wound uniformly without loosening or winding slack, and the line capacitance is stabilized to obtain a predetermined inductance. Further, in this embodiment, the protective layer 9 is provided on a part of the coil 8 to surely prevent winding looseness and loosening during molding of the coil 8, so that a predetermined inductance can be obtained.

On the other hand, when the chip inductor 1 is formed so that its outer dimensions are within a predetermined range, forming the core 2 in the shape of a quadrangular prism has the largest cross-sectional area. Therefore, as in the present embodiment, the winding core portion 3 is formed in a quadrangular prism shape,
The core 2 is formed in a substantially H-shaped planar shape by projecting quadrangular prismatic projecting edge portions 4 in a flange shape substantially perpendicularly from opposite sides of the longitudinal direction at both ends in the axial direction of the winding core portion 3. As a result, the core 2 having a wide cross-sectional area is obtained, and the chip inductor 1 having a high Q value is obtained. Further, since the volume of the core 2 of this embodiment is larger than that of the conventional drum type core, the magnetic characteristics are improved.

On the other hand, when the core 2 is molded with the mold resin and covered with the mold body 11, internal stress is generated by curing and contraction of the mold resin, and this internal stress acts on the core 2. Since the chip inductor 1 of this embodiment is molded into a rectangular parallelepiped shape so that the mounting surface on which the electrodes are formed is a flat surface for surface mounting, the conventional drum-type core has a molded body on the peripheral surface of the core. While the thickness is not uniform and the stress load concentrates on the thin portion of the core thickness and the magnetic susceptibility decreases, the core 2 of this embodiment has a prismatic shape. Are formed on the peripheral surface of the core 2 so as to have a substantially uniform thickness. Therefore, the internal stress generated when the mold body 11 is hardened and contracted is applied to the core 2 substantially uniformly, and in this embodiment, the internal stress is not locally concentrated, the magnetic permeability is less decreased, and the stable inductance is stable. Is obtained.

Further, in this embodiment, a conductive portion 5 is provided on a side surface of the projecting edge portion 4 of the core 2 which is flush with the core portion 3, and the conductive portion 5 is wound around the core portion 3. Since the lead wire 7a of the conducting wire 7 of the coil 8 and one end of the electrode piece 10 are electrically and mechanically connected in parallel to the magnetic flux direction, the magnetic flux generated when the coil 8 is energized intersects the electrode piece 10. The amount can be reduced and the Q value can be prevented from lowering.

[0034]

According to the chip inductor of the first aspect of the present invention, since the winding core of the core around which the coil is wound is formed in a prismatic shape, the coil can be wound without loosening or winding slack, and stable predetermined characteristics can be achieved. You can get it.

According to the chip inductor of the second aspect, in addition to the chip inductor of the first aspect, the projecting edge portion is formed in a quadrangular prism shape so as to project outwardly at a pair of opposite sides of the quadrangular prism core portion. Since the core is formed by providing the core, the volume of the core can be increased, the strain applied to the core due to the stress generated during the curing of the mold body can be reduced, and the decrease of the magnetic permeability can be prevented, so that the predetermined characteristics can be stably and easily obtained. be able to.

According to the chip inductor of claim 3, in addition to the chip inductor of claim 1 or 2,
On one side surface of the projecting edge portion of the core, a pair of conductive portions to which both ends of the coil are respectively connected and a pair of electrode pieces are respectively connected are provided in a direction parallel to the magnetic flux. It is possible to reduce the amount of magnetic flux that intersects and prevent the Q value from decreasing.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a chip inductor of the present invention.

FIG. 2 is a side view of the same.

FIG. 3 is a perspective view showing a core in a manufacturing process of the same chip inductor.

FIG. 4 is a perspective view showing the core after the conductive portion is formed in the manufacturing process of the same chip inductor.

FIG. 5 is a perspective view showing a situation in which a coil is wound in a manufacturing process of the same chip inductor.

FIG. 6 is a perspective view showing a state in which metal pieces are connected in a manufacturing process of the same chip inductor.

FIG. 7 is a perspective view showing a situation in which a protective layer is provided in a manufacturing process of the same chip inductor.

FIG. 8 is a perspective view showing a situation of molding in the manufacturing process of the same chip inductor.

FIG. 9 is a graph showing frequency characteristics of the same chip inductor.

FIG. 10 is a graph showing a DC superposition characteristic of the same chip inductor.

[Explanation of symbols]

 1 Chip Inductor 2 Core 3 Core Core 4 Projection Edge 5 Conductive Part 8 Coil 10 Electrode Piece 11 Molded Body

Claims (3)

[Claims] 1. A coil, a winding core portion around which the coil is wound, and flange-shaped projecting edge portions provided at both ends of the winding core portion in the axial direction around which the coil is wound. A core, a pair of electrode pieces provided at both ends of the core and connected to both ends of the coil, and a core around which the coil is wound and a molded body integrally embedding a part of the pair of electrode pieces In the chip inductor, the winding core portion of the core has a prismatic shape. 2. The winding core portion is formed in a quadrangular prism shape, and the projecting edge portion is formed in a quadrangular prism shape so as to project outward to a pair of opposite sides of the winding core portion. Chip inductor. 3. A pair of conductive parts, to which both ends of the coil are connected and a pair of electrode pieces are respectively connected, are provided on one side surface of the projecting edge part. Chip inductor.