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Method for manufacturing coil-embedded dust core and coil-embedded dust core

a technology of dust core and coil, which is applied in the field of manufacturing coilembedded dust core and coilembedded dust core, can solve the problems of coil damage, difficult compression,

Inactive Publication Date: 2005-02-10
TDK CORPARATION
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a method for manufacturing a coil-embedded dust core with a uniform density and reduced variation in inductance value. The method involves charging soft magnetic metal powder into a green body and compacting it in an axial direction of the air-core coil. By keeping the density of the soft magnetic metal powder in the parts corresponding to the winding section and the non-winding section equal, the density of the green body can be made uniform. The method also ensures that the coil is not damaged during the process. The coil-embedded dust core with a uniform density can achieve a stable inductance value.

Problems solved by technology

Since the coil is metal, it is more difficult to compress than soft magnetic metal powder, and the coil is sometimes damaged if it is forcefully pressurized.

Method used

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  • Method for manufacturing coil-embedded dust core and coil-embedded dust core
  • Method for manufacturing coil-embedded dust core and coil-embedded dust core
  • Method for manufacturing coil-embedded dust core and coil-embedded dust core

Examples

Experimental program
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Effect test

example 1

[0133] Thirty samples of the coil-embedded dust core having a core size of 12.5 mm long×12.5 mm wide×3.5 mm thick were made according to the following procedure:

[0134] The following were prepared: [0135] Magnetic powder: Permalloy powder manufactured through atomizing method (45% Ni—Fe; mean particle size 25 μm) [0136] Insulating material: silicone resin (SR2414LV by Toray Dow Corning Silicone Co., Ltd.) [0137] Lubricant: aluminum stearate (SA-1000 by Sakai Chemical Industry)

[0138] Next, 2.4 wt % of the insulating material was added to the magnetic powder, and these were mixed for 30 minutes at room temperature using a pressure kneader. Following this, the mixture was exposed to air and dried for 30 minutes at 150° C., thereafter 0.4 wt % of the lubricant was added to the dried magnetic powder and mixed for 15 minutes in a V mixer.

[0139] Subsequently, compressing was performed according to the procedure in FIG. 13A to FIG. 15D, and 30 compacted bodies are made. The coil 1 is form...

example 2

[0153] Out of the thirty samples made in the example 1, twenty samples were broken and the densities of the parts corresponding to the winding sections 3 of the coils 1 and the densities of the hollow parts of the coil 1 shown in FIG. 2A were measured using an Archimedean method with silicone oil. The result is shown in Table 1. Since the weight of each part is small, each part was taken out from twenty samples, and was measured together. The specific gravity of silicone oil is 0.817.

TABLE 1InIn airsiliconeDensity(g)oil (g)(g / cm3)Density of part8.5107.4416.50corresponding to windingsection 3 of coil 1Density of part7.2496.3276.42corresponding to hollowpart of coil 1

[0154] As shown in Table 1, the density of the part corresponding to the winding section 3 of the coil 1 shown in FIG. 2A was 6.50 g / cm3, and the density of the part corresponding to the hollow part of the coil 1 was 6.42 g / cm3. Namely, the difference between the density of the part corresponding to the winding section ...

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Abstract

It is an object to provide a method for manufacturing a coil-embedded dust core with a small variation in inductance value with efficiency and the like. A step (a) of charging soft magnetic metal powder including an insulating material, composing a green body 10, so as to cover a coil 1, and a step (b) of compacting the soft magnetic metal powder covering the coil 1 in an axial direction of the coil 1 are included, and in the step (b), the soft magnetic metal powder is compacted while an amount of the soft metal powder charged into the part corresponding to the winding section is kept smaller than an amount of the soft magnetic metal powder charged into the other part that are not corresponding to the winding section, with an upper surface or a lower surface of the winding section as a reference. Thereby, a coil-embedded dust core with entirely uniform density can be obtained, and according to the coil-embedded dust core with entirely uniform density, a variation in inductance value is reduced and it becomes possible to obtain a predetermined inductance value with stability.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a coil-embedded dust core, which may be used in inductors having a unitary structure with a magnetic core and in other electronic components. The present invention also relates to a method for manufacturing the coil-embedded dust core. More particularly, the invention relates to a method for manufacturing coil-embedded dust core constructed by embedding an air-core coil in a green body, and the like. [0003] 2. Description of the Related Art [0004] In recent years, electric and electronic equipment has become more compact, and dust cores that are compact (low in height) yet able to accommodate large current have come to be in demand. [0005] Materials used for dust cores are ferrite powder and ferromagnetic metal powder, but ferromagnetic metal powder has larger saturation magnetic flux density than ferrite powder and its DC bias characteristics may be maintained even in a strong magne...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B22F7/08A61B8/08H01F17/04H01F41/10
CPCA61B8/08A61B8/145Y10T29/49073Y10T29/49071Y10T29/4902A61B8/4483
Inventor SATOH, SADAKITAMURA, JUNETSUMORO, HIDEHARUSUZUKI, TSUNEO
Owner TDK CORPARATION
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