JPH10321438A - Surface mounting type inductor and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small surface mounting type inductor in which the top surface of a coating material has high flatness and dimensional accuracy. SOLUTION: A core 2 is constituted with a winding part 2c and two collar- like leg parts 2a and 2b provided on both end parts of the winding part 2c. A winding 5 is wound on the winding part 2c of the core 2. A coating material 18 provided with a flat top surface is provided on the top part of the core 2. The coating material 18 has a thickness 20 μm or below on the top surface and side surface of top collar parts 7a and 7b of the leg parts 2a and 2b. This coating material 18 is formed by soaking the top part of the core in liquid resin bath, formed into a specified thickness, and then drawing it up.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mount type inductor, for example, a surface mount type inductor used in a small electronic device such as a portable telephone and a method of manufacturing the same.

[0002]

2. Description of the Related Art As shown in FIG. 4, this type of surface mount type inductor comprises a winding portion 2c and two flange-shaped legs 2a and 2b provided at both ends of the winding portion 2c. ,
A surface mount type inductor 1 having a so-called horizontal type core 2 has been proposed. The winding 5 is wound around the winding part 2c. Both ends 5a and 5b of the winding 5 are
Are thermocompression-bonded to terminal electrodes 4a, 4b provided on the lower flanges 3a, 3b of the legs 2a, 2b, and are electrically connected.

A coating material 6 is provided on an upper portion of the core 2, and an upper portion of the winding 5 wound around the winding portion 2 c is covered with the coating material 6. The upper surface of the coating material 6 is flat. The reason why the upper surface of the coating material 6 is made flat is that when the inductor 1 is mounted on the circuit board, the suction by the suction nozzle can be reliably performed, and the winding 5 is not damaged by the suction by the suction nozzle. This is to prevent it.

[0004] The coating material 6 has conventionally been formed as follows. That is, as shown in FIG.
The coating material 6 is formed by immersing the winding 5 wound around the winding portion 2 c of the core 2 from the upper surface side of the core 2 into the concave portion 31 a of the mold 31 containing the liquid coating material 6, It is formed by curing the liquid coating material 6 in the recess 31a by light or heat and then removing the mold 31. Alternatively, separately, as shown in FIG.
The liquid coating material 6 having a high viscosity is provided between the upper flange portions 7a and 7b of the two legs 2a and 2b of the core 2 by a dispenser and cured.

[0005]

As shown in FIGS. 4 and 5, a coating material 6 is formed by using a mold 31. As shown in FIG.
In the inductor 1 in which is formed, the die 31 must be manufactured for each inductor size, and the manufacturing cost of the inductor 1 is high. In addition, it is necessary to use a concave portion 31 a having a dimension larger than the outer dimension of the core 2 in consideration of the clearance for inserting the core 2 in the mold 31. For this reason, since the coating material 6 protrudes from the side surface and the upper surface of the two leg portions 2a and 2b by dimensions d11 and d12 (see FIG. 4) corresponding to the clearance, there is a problem that the outer dimensions of the inductor 1 become large. . Further, since the coating material 6 is burred by the mold, there is a problem that the external dimension accuracy is poor.

On the other hand, in the inductor 1 shown in FIG.
Since no mold is required, manufacturing costs can be reduced. However, there is a problem that the shape of the coating material 6 varies due to the viscosity of the liquid coating material, and it is difficult to form the surface of the coating material 6 in a planar shape.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a small-sized surface-mount inductor having high flatness and dimensional accuracy on the upper surface of a coating material.

[0008]

In order to achieve the above object, a surface mount type inductor according to the present invention comprises (a) a winding portion and two flanges provided at both ends of the winding portion. (B) a winding wound around the winding part; and (c) an upper surface substantially flat and disposed on the upper part of the core, and A coating material having a thickness of 20 μm or less on the upper surface and the side surface of the flange portion.

Further, the method for manufacturing a surface mount type inductor according to the present invention comprises: (d) a step of winding a winding around a winding portion of a core; and (e) a step of applying a liquid coating material having a constant thickness on a flat plate. Forming; and (f) immersing the core in the liquid coating material until it comes into contact with the flat plate, and then lifting the core.
And (g) curing the liquid coating material applied to the core so that the upper surface of the core is substantially flat and the upper surface of the liquid coating material is formed on the leg of the core. The thickness on the top and side surfaces of the flange is 20
forming a coating material having a thickness of not more than μm.

[0010]

In general, the liquid coating material has a property of spreading thinly on the surface of the core. Therefore, when the upper part of the core is immersed in the liquid coating material and then pulled up, the upper flange portion of the leg is coated with a thin liquid coating material having a thickness of 20 μm or less. On the other hand, the upper surface of the winding portion is located at a position receded from the tip end surface of the upper collar portion of the leg portion, but the surface of the liquid coating material applied to the upper surface of the winding portion is a surface for reducing the surface area of the liquid coating material Due to the tension, a substantially coplanar surface is formed with the surface of the liquid coating material applied to the upper flange of the leg. For this reason, the liquid coating material applied to the upper surface of the winding part has a large thickness.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a surface mount type inductor and a method of manufacturing the same according to the present invention will be described with reference to the accompanying drawings.

As shown in FIGS. 1 and 2, the surface mount type inductor 11 is generally composed of a core 2, a winding 5, and a coating material 18. The core 2 has a winding portion 2c
And two flange-shaped legs 2a and 2b provided at both ends of the winding portion 2c. As a material of the core 2, a nonmagnetic ceramic material or a magnetic material such as ferrite is used. Leg 2
Ag, Cu, Ag- are provided on the lower flange portions 3a, 3b of the a, 2b.
Terminal electrodes 4a and 4b made of Pd or the like are provided, respectively.

The winding 5 is wound around a winding portion 2c of the core 2. Both ends 5a and 5b of the winding 5 are fixed to terminal electrodes 4a and 4b provided on the core 2 by means such as thermocompression bonding, and are electrically connected. As the winding 5, for example, a copper wire or the like coated with urethane resin is used. At both ends 5a and 5b, the urethane resin is scattered by heat applied at the time of thermocompression bonding or the like, and the copper wire is exposed. Will be.

A coating material 18 made of resin is provided on the upper part of the core 2, and the upper part of the winding 5 wound around the winding part 2 c is covered with the coating material 18. The upper surface of the coating material 18 is flat. Coating material 18
The reason for making the upper surface of the winding flat is to ensure that the suction by the suction nozzle can be performed when the inductor 11 is mounted on the circuit board and the like.
This is to prevent the damage of the. The coating material 18 has a thickness d2 on the upper surface of the upper flange portions 7a and 7b and a thickness d3 on the side surfaces of the leg portions 2a and 2b of 20 μm or less.

Here, the coating material 18 is formed as shown in FIG.
It is formed by the manufacturing steps shown in (A) to (D). That is, as shown in FIG. 3A, the core 2 around which the winding 5 is wound is held on the holding plate 21 at the distal end surfaces of the lower flanges 3a, 3b of the legs 2a, 2b. On the other hand, as shown in FIG. 3 (B), after flowing the liquid coating material 18 made of resin on the flat plate 22, the squeegee 24 is moved in the direction of arrow K to obtain a flat plate having a desired thickness. The liquid coating material 18 is formed.

Next, as shown in FIG. 3C, the core 2 is applied to the liquid coating material 18 and the upper flange 7 of the legs 2a and 2b.
a and 7b are immersed until they come into contact with the flat plate 22.
A liquid coating material 18 is applied to the upper part of the substrate. afterwards,
The core 2 is pulled up, and as shown in FIG. 3D, a liquid coating material 18 is attached to the winding 5 and the upper part of the core 2. At this time, the film thickness of the coating material 18 is such that the film thickness d2 on the upper surfaces and the film thickness d3 on the side surfaces of the upper flange portions 7a and 7b of the legs 2a and 2b of the core 2 is 20 μm or less.

On the other hand, the upper surface 2d of the winding 2c is connected to the legs 2a,
Although the surface of the liquid coating material 18 attached to the upper surface 2d of the winding portion 2c is located at a position retracted from the front end surfaces of the upper flange portions 7a and 7b, the surface tension of the liquid coating material 18 to reduce the surface area of the liquid coating material 18 The legs 2a, 2b
Coating material 1 attached to upper collar portions 7a, 7b
8 together with the surface of FIG. Therefore, the liquid coating material 18 adhered to the upper surface 2d of the winding portion 2c
Increases the film thickness. The liquid coating material 18 attached to the core 2 and the winding 5 is cured by light or heat.

The surface mount type inductor 1 thus obtained
1 is that the coating material 18 has two legs 2a,
Since the amount of protrusion from the side and top surfaces of 2b is extremely small, it is possible to obtain inductor 11 having small external dimensions. In addition, since a mold or the like is not used, the coating material 1
There is no need to worry about burrs, increase in manufacturing cost, etc., and the inductor 11 has good dimensional accuracy and is inexpensive.

It should be noted that the surface mount type inductor and the method of manufacturing the same according to the present invention are not limited to the above embodiment, but can be variously changed within the scope of the invention.

[0020]

As is apparent from the above description, according to the present invention, the coating material has a substantially flat upper surface and a thickness of 20 μm or less on the upper and side surfaces of the upper flange of the core leg. Therefore, the amount of protrusion of the coating material from the core can be reduced, and a small inductor can be obtained.

Further, a liquid coating material having a constant thickness is formed on a flat plate, and the core is dipped and pulled up until it comes into contact with the flat plate, so that the immersion depth of the core in the liquid coating resin becomes constant. An almost constant liquid coating material can always be adhered to the upper portion of the substrate, and a coating material having good dimensional accuracy and excellent flatness of the upper surface can be easily formed. Furthermore, since a mold or the like does not need to be used, manufacturing costs can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of a surface mount inductor according to the present invention.

FIG. 2 is a partial cross-sectional view of the surface mount inductor shown in FIG.

3A and 3B are diagrams illustrating a manufacturing process of the surface mount type inductor illustrated in FIG. 1, wherein FIG. 3A illustrates a state in which a core is temporarily fixed to a plate, and FIG. (C) shows a state in which the core is immersed in the liquid coating resin, and (D) shows a state in which the core is pulled up from the liquid coating resin.

FIG. 4 is a partial cross-sectional view showing a conventional surface mount type inductor.

FIG. 5 is a perspective view for explaining a coating material forming step of the surface mount inductor shown in FIG. 4;

FIG. 6 is a partial cross-sectional view showing another conventional surface mount inductor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 2 ... Core 2a, 2b ... Leg part 2c ... Winding part 5 ... Winding 7a, 7b ... Upper collar part 11 ... Surface mount type inductor 18 ... Coating material 22 ... Flat plate

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tetsuya Morinaga 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Inside Murata Manufacturing Co., Ltd.

Claims (2)

[Claims] 1. A core comprising a winding part, two flange-shaped legs provided at both ends of the winding part, a winding wound around the winding part, and the core And a coating material disposed on the upper part of the upper part and having a substantially flat upper surface and a thickness of 20 μm or less on the upper and side surfaces of the upper flange part of the leg part. 2. A step of winding a winding around a winding part of a core, a step of forming a liquid coating material having a constant thickness on a flat plate, and a step until the core comes into contact with the liquid coating material against the flat plate. Pulling up after dipping, applying a liquid coating material on the upper part of the core, and curing the liquid coating material applied to the core,
Forming a coating material having a substantially flat upper surface and a thickness of 20 μm or less on the upper surface and side surfaces of the upper flange portion of the leg portion of the core on the upper portion of the core. Method of manufacturing type inductor.