JP2005142380A - Coil component and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact coil component having a surface mounting structure for developing excellent characteristics without using any pot core, and to provide a method for manufacturing it. <P>SOLUTION: In a status that a coil is set in the cavity of a metallic mold, composite magnetic materials constituted of magnetic powder and polymer are made plastic, and packed in the cavity. Thus, it is possible to obtain a molded body where the surrounding and periphery of a coil are covered with the composite magnetic materials, and to provide a terminal for surface mounting by bending the terminal of the coil extended to the outside of the molded body along the side face of the molded body, and carrying out forming working. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a coil component used for an inductor or the like and a manufacturing method thereof.

  A coil around which a conductor is wound is often used in various forms as an important part constituting an electronic device. In order to meet the recent demands for downsizing and thinning of electronic devices, the structure of a coil for downsizing and surface mounting on a circuit board has been studied and put into practical use.

  As an example as described above, a coil component in which a coil is assembled to a magnetic core having a shape called a pot core is used. 4A and 4B are views showing an example of a pot core. FIG. 4A is a perspective view showing a state where the main body and the lid are separated, and FIG. It is a perspective view which shows the state which provided the terminal.

  In FIG. 4, 9 is a main body of the pot core, 10 is a center core, 11 is a lid, and 12 is a terminal for surface mounting. The main body 9, the core 10, and the lid 11 are made of a magnetic material typified by Ni—Zn-based ferrite, and constitute a closed magnetic circuit in the assembled state. Moreover, the terminal 12 is produced by drawing out the terminal of the coil accommodated inside, and performing forming processes, such as a crushing process and a bending process.

  5 is a view showing an example of a coil assembled to the pot core shown in FIG. 4, FIG. 5 (a) is a plan view, and FIG. 5 (b) is a perspective view. The example shown in FIG. 5 uses a conductor with a circular cross section, but in order to improve the space factor of the coil, a rectangular flat conductor with a flat cross section was bent and wound in the width direction. A coil formed by a method called edgewise winding is generally used.

  Thus, in order to further reduce the size of the coil component in which the coil is assembled to the pot core, it is naturally necessary to reduce the size of the pot core. However, a pot core is generally manufactured by pressing a magnetic oxide powder such as ferrite into a required shape and sintering, or by mixing a pulverized powder of a magnetic alloy with a binder and pressing it. Therefore, there is a limit to downsizing.

  On the other hand, in such a coil component, a sealing polymer is filled and bonded between the coil and the pot core, but in order to further improve the characteristics, the sealing high For example, magnetic powder is mixed and dispersed in molecules and used. For example, Patent Document 1 discloses a technique related to this.

  When the technology disclosed in Patent Document 1 is developed, a polymer containing magnetic powder is filled on the inner peripheral side of the coil, and at the same time, by covering the periphery of the coil, characteristics equivalent to those obtained by assembling the coil in the pot core are obtained. While maintaining, it can be expected that further downsizing is possible and the manufacturing process can be simplified. However, Patent Document 1 makes no mention of such a technique.

Japanese Patent Laid-Open No. 2003-224013

  Accordingly, an object of the present invention is to provide a coil component that has a small surface mounting structure without using a pot core and can be obtained by a simple process, and a method for manufacturing the coil component.

  This invention is made | formed as a result of examining using insert molding as a method of covering the inner periphery and circumference | surroundings of a coil with the polymer containing magnetic powder.

  That is, the present invention is a coil component characterized by having a coil whose inner periphery and periphery are covered with a magnetic material containing magnetic powder and polymer.

  Moreover, this invention is the said coil components, The said magnetic material comprises a closed magnetic circuit.

  In the present invention, the coil is inserted into the cavity of the mold, the plasticized magnetic material made of magnetic powder and polymer is filled in the cavity, and the magnetic material is solidified and then integrated. A coil component manufacturing method comprising the step of taking out the coil and the magnetic material from the cavity.

  In the present invention, as described above, in a state where the coil is held inside the cavity of the mold, a magnetic material (hereinafter referred to as a composite magnetic material) in which magnetic powder is mixed and dispersed in a polymer is plasticized. Since it is press-fitted into the cavity, a coil component having a required shape and having the inner periphery and the periphery of the coil covered with the composite magnetic material can be easily obtained.

  Insert molding is used as described above in the manufacture of the coil component of the present invention, particularly in the step of covering the inner periphery and the periphery of the coil with the composite magnetic material. For this, injection molding or transfer molding is used.

  Injection molding is a method in which a molten thermoplastic polymer is pressed into a cavity of a mold, and the injected thermoplastic polymer, that is, a molded product is cooled and solidified and taken out from the cavity. Transfer molding is mainly performed by heat. In this method, the curable polymer is melted and transferred to a cavity at a high pressure, and the transferred thermosetting polymer, that is, a molded product is taken out in a state where the curing reaction has progressed. Insert molding requires proper mold design due to the characteristics of the molding method, but both injection molding and transfer molding can be applied.

  As described above, since a thermoplastic polymer is basically used for injection molding, various polyolefins, polyamides, acrylic polymers, liquid crystals are specifically used for the composite magnetic material of the present invention. Examples thereof include linear polymers such as resins. However, in recent years, a technique using a thermosetting polymer for injection molding has also been developed, and thus the technology is not necessarily limited to a thermoplastic polymer.

  In addition, since a polymer that is cured by a crosslinking reaction is basically used for transfer molding, specific examples of the composite magnetic material of the present invention include an epoxy resin, an unsaturated polyester, and a rubber-based material. Can be mentioned. However, thermoplastic polymers can also be used by appropriately setting the molding conditions.

  In addition, the magnetic powder used in the composite magnetic material is basically not limited as long as it is obtained as a powder, and various oxide powders such as ferrite and magnetic alloy powders can be used depending on the required characteristics. It can be selected appropriately.

  Next, the present invention will be described in more detail with specific examples. Here, the example which covers a coil with a composite magnetic material using injection molding is demonstrated.

  First, the preparation process of a composite magnetic material is demonstrated. As the magnetic powder, an Mn—Zn ferrite powder having an average particle diameter of 3 μm was prepared. Moreover, nylon 12 was prepared as a thermoplastic polymer.

  In order to improve the fluidity in the molding process as a composite magnetic material, the ferrite powder was subjected to a surface treatment using a titanium-based coupling agent. The treatment method is as follows: 2 parts by weight of titanium-based coupling agent is weighed with respect to 100 parts by weight of ferrite powder, diluted by adding 20 times the amount of ethyl alcohol by volume, added to the ferrite powder, and stirred, then 80 ° C. And heated for 3 minutes.

  Next, 10 parts by weight of nylon 12 is weighed with respect to 100 parts by weight of the surface-treated ferrite powder, and the composite magnetic material for injection molding is simultaneously kneaded and pelletized using a twin-screw kneading extruder. Got.

  FIG. 3 is a cross-sectional view schematically showing the inside of an injection mold for insert molding. In FIG. 3, 4 is a cavity, 1 is a coil, 5 is a sprue, 6 is a runner, 7 is a gate, and 8 is an ejector pin. Here, the coil 1 having the same shape as that shown in FIG. 5 was used. However, a rectangular conductor made of a copper wire with polyurethane insulation was used as the conductor.

  As shown in FIG. 3, with the coil 1 installed in the cavity 4, the mold temperature is set to 100 to 120 ° C., and the composite magnetic material plasticized by heating to 240 ° C. is sprue 5, runner 6, gate The cavity 4 was filled via 7. After completion of filling, the molded body was cooled by holding for 12 seconds, the mold was opened, and the ejector pins 8 were taken out.

  2A and 2B are perspective views showing the external appearance of the coil component. FIG. 2A shows a state immediately after the coil component is taken out from the mold, and FIG. 2B shows a state where the terminals are subjected to forming processing. Moreover, FIG. 1 is a figure which shows the completion state of the coil component of a present Example, FIG. 1 (a) is a top view, FIG.1 (b) is a front view. 1 and 2, 2 is a coil component body, and 3 is a terminal.

  As shown in FIG. 2, the terminal 3 is extended in the horizontal direction in the drawing immediately after being taken out of the mold, so it is bent along the side surface of the coil component body 2 and bent to the bottom surface for surface mounting. Terminal. At this time, the terminal 3 may be appropriately crushed to enlarge the area as a surface mounting terminal.

  Moreover, since the composite magnetic material covering the inner periphery and the periphery of the coil is in a continuous state, it forms a closed magnetic circuit. If necessary, it is easy to form a magnetic gap by inserting an appropriate member into the cavity during insert molding.

  In addition, although the example which used the injection molding for the insert molding was shown in the said Example, transfer molding can also be used, and other molding methods, such as press molding, should examine die design etc. suitably. And applicable.

The figure which shows the completion state of a coil component. FIG. 1A is a plan view. FIG. 1B is a front view. The perspective view which shows the external appearance of a coil component. FIG. 2A shows a state immediately after taking out from the mold. FIG. 2B shows a state where the terminal is subjected to forming processing. Sectional drawing which showed typically the inside of the metal mold | die for injection molding which performs insert molding. The figure which shows an example of a pot core. FIG. 4A is a perspective view showing a state in which the main body and the lid are separated. FIG. 4B is a perspective view showing a state where a coil and a lid are assembled to provide a surface mounting terminal. The figure which shows an example of a coil. FIG. 5A is a plan view. FIG. 5B is a perspective view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Coil 2 Coil components main body 3,12 Terminal 4 Cavity 5 Spru 6 Runner 7 Gate 8 Ejector pin 9 Main body (pot core) 10 Core 11 Cover

Claims (3)

  A coil component comprising a coil whose inner periphery and periphery are covered with a magnetic material containing magnetic powder and a polymer.   The coil component according to claim 1, wherein the magnetic material forms a closed magnetic path.   The coil is inserted into a cavity of a mold, a plasticized magnetic material made of magnetic powder and polymer is filled in the cavity, and the magnetic material is solidified. A method for manufacturing a coil component, comprising the step of taking out the magnetic material from the cavity.

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