JP2002170717A - Chip inductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit the leakage of an electromagnetic wave at a low value, and to enable high-density mounting in a chip inductor. SOLUTION: A bobbin 11 is formed by installing leg sections 11b and 11c at both ends of a cylindrically formed core section 11a so as to be approximately crossed at right angles with the axial center of the core section 11a, and external electrodes 13a and 13b are formed so as to cover side faces at both ends in the direction of the axial center of the core section 11a in at least the leg sections 11b and 11c.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip inductor used for various electronic devices, and more particularly, to a wound type chip inductor.

[0002]

2. Description of the Related Art Conventionally, wound type chip inductors have been used in various electronic devices such as mobile phones and personal computers. This wire-wound chip inductor is composed of a bobbin formed by attaching legs substantially vertically to both ends in the axial direction of a pillar-shaped core portion around which the coil is wound, and a coil wound around the bobbin. An external electrode electrically connected to the coil is provided on the bottom side of the leg of the bobbin.

[0003] The materials used for bobbins are generally alumina, ferrite, resin and the like.
For example, an insulated copper wire having a diameter of about 0.02 to 0.1 mm is used. The external electrodes are formed by applying and baking a thick film paste such as Ag, Ag-Pd, Mo-Mn, W, Ni,
It is formed by patterning a metal such as Cu by metallization and plating the surface with Ni, Cu, Sn, solder or the like.

[0004] The chip inductor thus configured is mechanically and electrically connected to the circuit pattern by soldering the external electrodes provided on the legs onto the substrate on which the circuit pattern is formed. Is done.

[0005]

However, with the recent miniaturization of electronic devices such as mobile phones, high-density mounting of electronic components such as chip inductors constituting the electronic devices has been rapidly progressing. When a chip inductor having a conventional configuration is mounted close to such an electronic device, there is a problem that the characteristics of other chip inductors arranged around the device vary due to electromagnetic waves leaking from the chip inductor.

[0006] Such a problem can be solved simply by arranging the chip inductors alone, for example, when the gain varies due to the extension of the antenna as in a coupling circuit formed in an antenna section of a cellular phone or the like. It is especially serious because it is a problem that cannot be done.

The present invention has been made in view of the above points, and has as its object to provide a chip inductor suitable for high-density mounting while suppressing leakage of electromagnetic waves.

[0008]

According to the present invention, in order to solve the above-mentioned problems, in a wire-wound chip inductor, a pillar-shaped core portion and two ends of the core portion are provided at both ends of the core portion. A bobbin having a leg provided so as to be substantially perpendicular to the axis, a coil wire wound around the core, and arranged with both ends led out, and the two ends of the coil wire Parts are electrically connected to each other, and have an external electrode formed so as to cover at least a part of the bottom surface of the leg and a side surface corresponding to an axial end of the core in the leg. A featured chip inductor is provided.

Here, the core part functions as a winding axis of the coil wire, the leg part arranges the core part at a fixed height from the mounting substrate, and the coil wire functions as an inductor. The external electrode fixes both ends of the coil wire and is conductively connected to a circuit pattern on the mounting board via solder or the like.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. First, a first embodiment of the present invention will be described.

FIGS. 1 to 3 are structural views showing the configuration of a chip inductor 10 according to this embodiment. Here, FIG.
FIGS. 2A and 2B are perspective views showing the configuration of the chip inductor 10, FIG. 2A is a front view thereof, FIG.
3C is a bottom view, FIG. 3A is a right side view, and FIG. 3B is a left side view.

The chip inductor 10 has a core 11a formed in a columnar shape, and a core 11a at both ends of the core 11a.
leg 11 projecting so as to be substantially perpendicular to the axis of a
b, 11c, a coil core 12 wound around a core 11a, and a coil wire 12 arranged with both ends thereof extended outside, and both ends of the coil wire 12 electrically connected to each other, and at least a leg External electrodes 13a and 13b are formed so as to cover a part of the bottom surfaces of the portions 11b and 11c and side surfaces of the legs 11b and 11c at both ends in the axial direction of the core 11a.

As long as the core part 11a constituting the bobbin 11 is formed in a columnar shape as described above, there is no particular limitation on its shape, such as a cylinder or a prism.
It is still more preferable that the magnetic head is of a wide flat type so that the influence of the magnetic flux generated from zero on nearby components can be reduced.

The leg portions 11b and 11c are formed in a columnar shape such as a prism, and are formed at both ends in the axial direction of the pillar shape constituting the core portion 11a at substantially perpendicular to the axis of the core portion 11a. 11a
And are formed integrally. At this time, the core 11a and the leg 11
The positions where b and 11c are in contact with each other are set at relatively high positions at the same distance from the bottom surfaces of the legs 11b and 11c. When the chip inductor 10 is mounted, the core 11a In other words, it is arranged at a relatively high position from the mounting surface and substantially parallel to the mounting surface.

Here, the bobbin 11 has a ratio of the total length L1 + L3 of the thickness L1 of the leg 11b and the thickness L3 of the leg 11c in both end directions of the core 11a to the length L2 of the core 11a. It is configured to fall within the range of 2 to 1: 1. With such a ratio, a magnetic path can be secured and Q can be kept high.

The material forming the core 11a and the legs 11b and 11c may be either a magnetic material such as ferrite or a non-magnetic material such as alumina or resin. It is more preferable to use a non-magnetic material in order to reduce the inductance and suppress the influence of the magnetic flux generated from the chip inductor 10 on other components.

The coil wire 12 is an insulated conductor having a diameter of about 0.02 to 0.1 mm formed by coating a linear conductor such as Cu with an insulating film such as a polyurethane resin. Coil wire 1 formed as follows
2 is wound around the core 11a a plurality of times, and both ends thereof are electrically connected and fixed to the external electrodes 13a and 13b, respectively. Here, as a conductor material used for the coil wire 12, if the electric resistance is low and suitable for winding,
A chrome-plated copper wire can be used without particular limitation.

The external electrode 13a is formed in a continuous L-shaped cross section from the bottom surface to the outer side surface of the leg 11b.
The portion of the external electrode 13a disposed on the outer side surface of the leg 11b is configured to cover at least the outer side surface corresponding to one end of the leg portion 11b in the axial direction of the core 11a. The external electrode 13b is connected to the leg 11
c is formed in a continuous L-shaped cross section from the bottom surface to the outer side surface, and at least a portion of the external electrode 13b disposed on the outer side surface of the leg 11c is
The outer side surface corresponding to the other end in the axial direction of the core portion 11a in FIG. External electrodes 13a, 1
In the configuration of 3b, if a material having high conductivity and high adhesion strength to the bobbin 11 is used, a thick film paste such as Ag or Ag-Pd is printed and baked, or Mo-Mn, W, N
A pattern formed by metallizing a metal such as i or Cu can be used without particular limitation, for example, a pattern obtained by plating the surface with Ni, Cu, Sn, solder, or the like.

FIG. 4 is a front view showing the distribution of the magnetic flux 20 when the thus configured chip inductor 10 is arranged close to the side direction. As shown in FIG. 4, in the chip inductor 10, the legs 11b, 11c
Are covered with the external electrodes 13a and 13b, the side surfaces corresponding to both ends in the axial direction of the core 11a in FIG.
The wraparound of the magnetic flux 20 from the side of the side 11c is blocked by the external electrodes 13a and 13b formed on the side. Thereby, a plurality of chip inductors 1
In the case where 0 is arranged close to the axial direction of the core portion, it is possible to reduce the wraparound of the magnetic flux 20 in the axial direction of the core portion where adjacent chip inductors 10 have the greatest effect on each other. , Chip inductor 10
Can be mounted at a high density.

FIG. 5 is a block diagram showing a configuration example of an antenna input / output circuit 30 using such a chip inductor. As shown in FIG.
Is composed of capacitors 32a and 32b and chip inductors 31a and 31b having the configuration according to the present embodiment.
The chip inductor 31a is connected to the antenna 40.

The chip inductors 31a and 31b are connected in series, and the chip inductor 31b is connected to the ground. Also, a capacitor 32a connected to the antenna
Is connected to the ground, and the capacitor 32b is connected to the IC
Connected to.

Here, the magnetic field distribution of each of the chip inductors 31a and 31b constituting the antenna input / output circuit 30 is similar to the magnetic field distribution shown in FIG. 31a, 3
If the antennas 1b are arranged side by side, even if the gain fluctuates due to the extension of the antenna 40, the chip inductors 31a, 31b close to the chip inductors 31a, 31b are generated by magnetic flux generated from the chip inductors 31a, 31b. Characteristic variation can be suppressed.

As described above, in this embodiment, the external electrodes 13
a, 13b are formed so as to cover at least the side surfaces at both ends of the leg portions 11b, 11c in the axial direction of the core, so that the magnetic flux 20 wraps around the leg portions 11b, 11c from the side surface direction. 13a and 13b, the chip inductor 1
0 high-density mounting becomes possible.

Next, a second embodiment of the present invention will be described. This embodiment is a modification of the first embodiment, and is different from the first embodiment in the formation position of the external electrode. In the following, description will be made focusing on differences from the first embodiment, and description of items common to the first embodiment will be omitted.

FIG. 6 is a perspective view showing a state in which the chip inductors 40 and 50 in the present embodiment are arranged side by side in the side direction of the core 41a. As shown in FIG. 6, the chip inductor 40 also has a core portion 41a and leg portions 41b, similarly to the chip inductor 10 according to the first embodiment.
Bobbin 41c, coil wire 42, and external electrode 4
3a and 43b. The difference from the first embodiment is that the external electrodes 43b are not only provided on the bottom surface of the leg 41c and the side surfaces at both ends in the axial direction of the core 41a of the leg portion, but also on the side surface of the adjacent chip inductor 50. (Side of the core 41a). The external electrodes 43b on the side surfaces of the core portion 41a formed here may be formed on both side surfaces of the core portion 41a, or may be formed only on the side surfaces on the adjacent chip inductor 50 side. Good. In addition, the external electrode 4
Instead of 3b, the external electrode 43a may be formed only on both side surfaces of the core 41a or only on the side surface of the adjacent chip inductor 50. Further, in both of the external electrodes 43a and 43b, the external electrodes 42a and 43
It is good also as a structure which forms b.

As described above, in this embodiment, since the external terminals 43b are provided on at least a part of the side surface of the leg portion 41c on the side of the adjacent chip inductor, a plurality of chip inductors are provided in the side surface direction of the core portion 41a. Even if they are arranged side by side, the effect on other chip inductors by the magnetic flux generated from the chip inductor is reduced,
Chip inductors can be mounted at high density.

[0027]

As described above, in the chip inductor according to the present invention, since the external electrodes are formed so as to cover at least the side surfaces at both ends in the axial direction of the core portion of the leg portion, the external electrodes are formed from the chip inductor. Electromagnetic wave leakage can be kept low, and high-density mounting of chip inductors becomes possible.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a chip inductor.

2A is a front view showing a configuration of a chip inductor, FIG. 2B is a plan view thereof, and FIG. 2C is a bottom view thereof.

FIG. 3A is a right side view showing a configuration of a chip inductor, and FIG. 3B is a left side view thereof.

FIG. 4 is a front view showing the distribution of magnetic flux when the chip inductor is arranged close to the core axis direction.

FIG. 5 is a block diagram showing a configuration example of an antenna input / output circuit using a chip inductor.

FIG. 6 is a perspective view showing a state in which chip inductors are arranged side by side in a side direction of a core.

[Explanation of symbols]

10, 31a, 31b, 40, 50: chip inductor, 11: bobbin, 11a, 41a: core part, 11b,
11c, 41b, 41c leg, 12, 42 coil wire, 13a, 13b, 43a, 43b external electrode, 20
... magnetic flux

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Sadaaki Kurata F-term (reference) in Taiyo Denki Co., Ltd. 6-16-20 Ueno, Taito-ku, Tokyo 5E070 AA01 AB08 BA03 CA12 EA02

Claims (5)

[Claims] 1. A wound type chip inductor, comprising: a core portion formed in a columnar shape; and both ends in the axial direction of the core portion projecting so as to be substantially perpendicular to the axis of the core portion. A bobbin having a leg portion, a coil wire wound around the core portion, and both end portions of the coil wire arranged in a state of being led out to the outside; and both end portions of the coil wire are electrically connected to each other. An external electrode formed so as to cover a part of the bottom surface of the leg portion and a side surface corresponding to an axial end of the core portion of the leg portion. 2. The chip inductor according to claim 1, wherein the external electrode is formed in an L-shaped cross section from a bottom surface to a side surface of the leg. 3. The ratio of the total thickness of the leg portions in the axial direction of the core to the length of the core is in the range of 1: 2 to 1: 1. Item 7. The chip inductor according to Item 1. 4. The chip inductor according to claim 1, wherein said bobbin is made of a non-magnetic material. 5. The chip inductor according to claim 1, wherein the core is a wide flat type.