JP3439829B2 - Manufacturing method of inductor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an inductor comprising a coil-shaped conductor covered with an insulating coating and a magnetic part formed by enclosing the coil-shaped conductor. 2. Description of the Related Art Inductors such as a smoothing choke coil and a noise filter of a power supply, which are formed by winding a conductor insulated and coated on a toroidal magnetic core, are often used because of its simplicity. However, with the recent downsizing of electronic devices and integration of parts, inductors have been required to have an outer shape and dimensions suitable for downsizing and surface mounting. The structure of winding a conductor coated with insulation on a toroidal magnetic core,
As the miniaturization progresses, it becomes difficult to perform winding, and it is difficult to obtain an outer shape and a dimensional ratio suitable for surface mounting. Therefore, an inductor in which a conventionally used toroidal magnetic core wound with a conductor covered with an insulating material is sealed with a resin or a resin containing a magnetic material, or a thin plate composed of a conductor and a magnetic material is used as a conductor. Inductors which are alternately laminated and sintered so that a part of them has a contact have come to be used.
However, an inductor in which a conductor insulated and coated on a toroidal magnetic core is sealed with a resin or a resin containing a magnetic material does not have a large inductance with respect to dimensions, and thus cannot sufficiently meet the demand for miniaturization. On the other hand, inductors made by laminating and sintering thin plates composed of conductors and magnetic materials alternately so that some of the conductors have contacts make it possible to efficiently surface mount even if the size is reduced because the magnetic flux generated by the coil does not leak outside However, it is necessary to use a noble metal such as silver or palladium for the conductor, and it requires special manufacturing equipment, the manufacturing process is complicated and the manufacturing cost is high, The constituents of the material and the magnetic material are mutually diffused, and the characteristics of the material to be used are also reduced in terms of magnetic characteristics by 10
There is a disadvantage that 0% cannot be expressed. To overcome the disadvantages of these inductors, an insulated conductor is wound and pressed to enclose it in a mixture of magnetic powder and binder in a volume ratio of 6: 4 to 9: 1. A molded inductor has been proposed (see Japanese Patent Application No. 5-291046). This inductor can satisfy the requirements of miniaturization and surface mounting. [0005] However, the inductor having such a structure has a non-uniform pressure distribution in a metal mold at the time of press molding, and is liable to cause displacement of the coil and deformation of the coil. As a result, it cannot be manufactured as designed and the defect rate increases. In addition, if the mixing ratio of the magnetic powder to the resin is increased to improve the performance, the mixture becomes a sticky and lumpy lump, and it is difficult to insert the mixture into the mold. Can not be arranged. Further, the lead wire from the coil impairs the operability during pressure molding. [0006] The present invention solves the above-mentioned problems in inductors, and comprises expensive metal, special manufacturing equipment,
Alternatively, a complicated manufacturing process is not required, the original characteristics of the magnetic material and the conductor can be expressed 100%, the manufacturing cost is low, and the pressure molding process is not required. There is no risk of displacement or deformation of the coil, the coil can be precisely placed at the desired position and shape, and the magnetic characteristics as designed can be exhibited.The inductor can be manufactured in a small size and suitable for surface mounting. It is intended to provide a manufacturing method. SUMMARY OF THE INVENTION The present invention provides a step of winding a conductor coated with insulation in the form of a coil, a step of mixing and kneading a magnetic substance and an epoxy resin, and a step of mixing and kneading the magnetic substance. By embedding the coil-shaped conductor in a mixture of the epoxy resin and a kneaded magnetic material and removing the excess epoxy resin from the mixture of the epoxy resin by centrifugal force and then curing. The above problem is solved by manufacturing an inductor. [0008] Since the coil-shaped conductor is buried in a mixture of a magnetic substance and an epoxy resin without excessive pressure molding, excess epoxy resin is removed by centrifugal force and hardened. , The mixture can be easily charged, there is no risk of coil displacement or coil deformation, and the coil can be precisely positioned at the desired position and shape, regardless of the mixing ratio of the magnetic substance and epoxy resin. A molded article having a constant density can be stably manufactured. FIG. 1 is a perspective view of an inductor manufactured by a method of manufacturing an inductor according to an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of an inductor manufactured by the manufacturing method,
FIG. 3 is an explanatory view of a step of embedding a coil-shaped conductor in a mixture of a kneaded magnetic substance and an epoxy resin, and FIG. 4 is a diagram showing an excessive epoxy resin from a mixture of a kneaded magnetic substance and an epoxy resin. It is explanatory drawing of the process of removing by centrifugal force. In the method of manufacturing the inductor 1 of this embodiment, first, the conductor 2 covered with the insulation is wound in a coil shape.
The conductor 2 is not particularly limited in its cross-sectional shape, thickness, etc. as long as its surface is insulated and coated with an enamel coating or the like, and is optimal in view of magnetism, electric characteristics and workability required for the inductor 1. The shape and thickness may be determined. In addition, the shape of the coil to be wound includes, for example, a coil having a cross-sectional shape of a circle or a square, which is manufactured by winding, but is not limited thereto. Is also good. Next, the magnetic material and the epoxy resin are mixed and kneaded to produce a mixture 5. The magnetic material is not particularly limited as long as it has soft magnetic characteristics. But,
From the viewpoint of economy and magnetic properties such as magnetic permeability, the metal magnetic material is preferably, for example, iron powder, iron-silicon alloy, iron-silicon-aluminum alloy, iron-nickel alloy, or the like. The particle diameter of the magnetic material is not particularly limited, but is preferably in the range of 20 to 500 μm, and more preferably in the range of 50 to 300 μm in terms of increasing the productivity and the density of the inductor 1. The kind of the magnetic substance to be used may be a single kind or a mixture of two or more kinds. As the epoxy resin, a one-pack type or two-pack type epoxy resin which is used as it is or diluted with a solvent to adjust the viscosity is used. Epoxy resins having a longer pot life are easier to produce, but shorter finger contact times after molding are more productive. Also, a thermosetting resin or a thermosetting resin can be used, but the thermosetting resin must be curable at a temperature within a range that does not impair the insulating coating of the conductor 2. As for the viscosity of the epoxy resin, a low viscosity makes it easier to remove excess resin, but a high viscosity is better to keep the composition of the mixture uniform over a long period of time, so select an appropriate range of viscosity. . The ratio of the magnetic substance to the epoxy resin is made richer in a range in which the mixture 5 can be automatically and quantitatively supplied to the container 6, so that the molding time can be shortened and the cost can be reduced.
Then, the coiled conductor 2 is positioned in the container 6,
A predetermined amount of the mixture 5 is supplied into the container 6 with the measuring cup 7,
A coil-shaped conductor 6 is embedded in a mixture 5 of a kneaded magnetic substance and an epoxy resin. At this time, the mixture 5 of the magnetic substance and the epoxy resin contains an excessive amount of the epoxy resin in order to enable automatic quantitative supply. Since the container 6 can be an open type, accurate positioning of the coil made of the conductor coated with insulation is possible,
Deterioration of operability due to the external electrode 3 of the coil can be avoided. Since pressure molding is not performed, the container 6 does not need to have high pressure resistance and can be made thinner. The shape of the container 6 can be appropriately selected as long as the conductor 2 wound in a coil shape, such as a cylindrical shape or a donut shape, can be accommodated therein, in addition to the hexahedron as shown in FIG. The main function of the epoxy resin is to maintain the shape of the inductor 1 and to insulate between the magnetic powders.
It is preferable that the number is small in the inductor 1. Then, the container 6 in which the coil-shaped conductor 2 is embedded in the mixture 5 of the kneaded magnetic substance and the epoxy resin is attached to the rotating shaft 9 with the support 8 so that the bottom surface 6B is on the outside, and the rotation is performed. give. A large number of pores 10 are formed in the bottom surface 6B of the container 6, and when the container 6 is rotated, the epoxy resin 11 excessively added to enable automatic quantitative supply is removed from the pores 10. Removed by centrifugal force. Excessive epoxy resin 11 is eliminated, and the magnetic material is densified and the predetermined magnetic portion 4 is removed.
Is formed, the container 6 is removed from the rotating shaft 9 and hardened. Through the above steps, the inductor 1 including the coil-shaped conductor 2 covered with the insulating coating and the magnetic part 4 formed by enclosing the coil-shaped conductor 2 is formed. (Example 1) An alloy powder composed of 9.5% by weight silicon, 5.5% by weight aluminum, and the balance of iron produced by a water atomization method was sieved to collect only a powder having a particle diameter of 63 to 106 µm. This was heat-treated at 1000 ° C. for 2 hours in an argon atmosphere, and 22 g of magnetic powder and 11 g of a two-part epoxy resin (viscosity at mixing 650 cps, specific gravity 1.2) were mixed and kneaded in a measuring cup. Then, a mixture was prepared. An enamel-coated copper wire having a diameter of 0.3 mm is wound on a cylinder having an outer diameter of 18 mm to form a coil having a height of 6 mm and a volume of 40 turns. The mixture is filled in this mold, the excess epoxy resin is removed from the pores at the bottom of the mold by applying a centrifugal force of 10 G, and the magnetic powder is concentrated. The epoxy resin was cured by leaving it to stand overnight, and this was removed from the mold to form an inductor. The obtained inductor has a bottom surface of 30 × 30.
It was a hexahedron having a height of 10 mm and a height of 10 mm. The magnetic powder was uniformly distributed in the resin, and had sufficient strength against external force. As a result of measuring the inductance with an LCR meter, the inductance was 210 μH at a frequency of 1 kHz. (Example 2) Pure iron (purity 9) produced by an electrolysis method
9.9% or more) in a nitrogen atmosphere, and sieved to collect a powder having a particle diameter of 63-150 μm,
C, 16 g of magnetic powder heat-treated in an argon atmosphere for 2 hours, and a two-part epoxy resin (viscosity of 650 when mixed)
cps, specific gravity 1.2) 8 g in a measuring cup,
The mixture was kneaded to prepare a mixture. An enamel-coated copper wire having a diameter of 0.3 mm is wound on a cylinder having an outer diameter of 18 mm to form a coil having a height of 6 mm and 40 turns. This coil is previously formed into a cylindrical mold having a bottom surface having an inner diameter of 30 mm. After the center axis is overlapped, the mixture is filled in the mold, and the excess epoxy resin is removed from the pores at the bottom of the mold by applying a centrifugal force of 10 G, and the magnetic powder is concentrated. The epoxy resin was cured by leaving it at room temperature overnight, and the epoxy resin was removed from the mold to obtain an inductor. The obtained inductor has a bottom surface of 30 m in diameter.
It had a circular shape of m and a cylindrical shape with a height of 10.2 mm. The magnetic powder was uniformly distributed in the resin, and had sufficient strength against external force. As a result of measuring the inductance with an LCR meter, the inductance was 190 μH at a frequency of 1 kHz. (Example 3) An alloy powder composed of 9.5% by weight of silicon, 5.5% by weight of aluminum and the balance of iron produced by a water atomization method was sieved to collect only a powder having a particle diameter of 63 to 106 µm. This was heat-treated at 1000 ° C. for 2 hours in an argon atmosphere, with 4.5 g of a magnetic powder and a two-part epoxy resin (viscosity at mixing 650 cps, specific gravity 1.2) 2.3.
g was mixed and kneaded in a measuring cup to prepare a mixture. An enamel-coated copper wire having a diameter of 0.3 mm is wound around a cylinder having an outer diameter of 7 mm to form a coil having a height of 5 mm and 40 turns. The mixture is filled in the mold, the excess epoxy resin is removed from the pores at the bottom of the mold by applying a centrifugal force of 10 G, and the magnetic powder is concentrated. The epoxy resin was cured by leaving it to stand overnight, and this was removed from the mold to form an inductor. The obtained inductor has a bottom surface of 10 × 20
It was a hexahedron having a height of 10 mm and a height of 10 mm. The magnetic powder was uniformly distributed in the resin, and had sufficient strength against external force. As a result of measuring the inductance with an LCR meter, it was 35 μH at a frequency of 1 kHz. As described above, according to the inductor manufacturing method of the present invention, expensive metal, special manufacturing equipment,
Alternatively, an inductor that does not require a complicated manufacturing process and can realize 100% of the original characteristics of the magnetic body and the conductor can be manufactured at low cost. In addition, since there is no need for a pressure molding process, there is no risk of coil displacement or coil deformation, and the coil can be accurately placed at the desired position and shape, and can exhibit magnetic characteristics as designed. Thus, an inductor suitable for surface mounting can be manufactured.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an inductor manufactured by a method for manufacturing an inductor according to an embodiment of the present invention. FIG. 2 is a longitudinal sectional view of an inductor manufactured by this manufacturing method. FIG. 3 is an explanatory view of a step of embedding a coiled conductor in a mixture of a kneaded magnetic substance and an epoxy resin. FIG. 4 is an explanatory view of a step of removing an excess epoxy resin from a mixture of a kneaded magnetic substance and an epoxy resin by centrifugal force. [Description of Signs] 1 Inductor 2 Conductor 3 External electrode 4 Magnetic part 5 Mixture 6 Container 6B Bottom 7 Measuring cup 8 Support 9 Rotating shaft 10 Pores 11 Epoxy resin

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kenichi Nagatsuma 20 Kamiyoshima Kodate, Yoshima-cho, Iwaki-shi, Fukushima Furukawa Machinery & Metal Co., Ltd. Iwaki Plant (56) References JP-A-5-114527 (JP, A JP-A-6-84648 (JP, A) JP-A-1-147813 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01F 41/02 H01F 3/08 H01F 27 / 255 H01F 27/32 H01F 41/04 H01F 41/12

Claims (1)

(57) [Claim 1] A step of winding a conductor coated with insulation in the form of a coil, a step of mixing and kneading a magnetic substance and an epoxy resin, and a step of mixing and kneading the kneaded magnetic substance and epoxy. An inductor comprising: a step of embedding the coiled conductor in a mixture with a series resin; and a step of removing excess epoxy resin from the mixture of the kneaded magnetic substance and the epoxy resin by centrifugal force and then curing the mixture. Manufacturing method.