JP2008192893A - Magnetic thin member, magnetic element using the same, and method of manufacturing the magnetic thin member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase a DC bias characteristic in a magnetic element using a magnetic thin member. <P>SOLUTION: A magnetic thin member 4 comprises sheets 5 made of a magnetic material, and air holes 6 are provided in the sheet 5. With such an arrangement, the provision of the air holes 6 enables reduction of the permeability of a magnetic thin member 4. Thus even when a large current flows through a coil 8, this causes no saturation of a magnetic flux. Consequently a high DC bias characteristic can be obtained. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a magnetic element used for an inductor, a choke coil, a transformer and the like of an electronic device, a magnetic thin body constituting the magnetic element, and a manufacturing method thereof.

  Conventionally, as shown in FIGS. 1 and 2, this type of magnetic element includes a magnetic body 1 formed by laminating magnetic thin bodies made of a magnetic material, a coil 2 for generating a magnetic flux flowing in the magnetic body, and this coil. 2 and a terminal 3 electrically connected to 2.

As prior art document information relating to this application, for example, Patent Document 1 is known.
Japanese Patent Laid-Open No. 11-2119833

  Such a conventional magnetic element has a problem of low DC superposition characteristics.

  That is, in the above conventional configuration, as the current flowing through the coil 2 is increased, the amount of magnetic flux generated in the coil 2 is increased, and as a result, the amount of magnetic flux that can pass through the magnetic thin body is saturated. The problem is that the DC superposition characteristics are low.

  Accordingly, an object of the present invention is to improve the DC superposition characteristics of a magnetic element using such a magnetic thin body.

  In order to achieve this object, the present invention is configured such that the magnetic thin body includes a sheet made of a magnetic material, and pores are provided in the sheet.

  With this configuration, the magnetic element of the present invention reduces the magnetic permeability of the magnetic thin body due to the presence of pores, so that the magnetic flux does not saturate even when a large current is passed through the coil. Obtainable.

(Embodiment 1)
Hereinafter, a magnetic thin body and a magnetic element using the same according to Embodiment 1 of the present invention will be described with reference to the drawings.

  As shown in FIG. 3, the magnetic thin body 4 in the present embodiment includes a sheet 5 made of a magnetic material, and pores 6 are provided in the sheet 5.

  By providing such pores 6, the magnetic permeability of the magnetic thin body 4 can be reduced.

  Next, a magnetic element using this magnetic thin body will be described.

  As shown in FIG. 4, the magnetic element in the present embodiment includes a laminated core 7 made of a magnetic thin body 4, a coil 8 that generates a magnetic flux flowing through the laminated core, and a terminal electrically connected to the coil 8. 9.

  With such a configuration, the magnetic permeability of the magnetic thin body 4 can be lowered due to the presence of the pores 6. As a result, the magnetic flux does not saturate even when a large current is passed through the coil 8, and high DC superposition characteristics are obtained. It can be done.

  In addition, as for the content rate of the pore 6 in the magnetic thin body 4, it is desirable to set it as 3 vol% or more and 50 vol% or less. This is because, by setting it to 3 vol% or more, it is possible to secure the effect of improving the DC superposition characteristics, and by setting it to 50 vol% or less, it is possible to suppress a significant decrease in magnetic permeability.

  As the magnetic material constituting the sheet 5, it is desirable to use a metal magnetic material such as Fe, Fe—Si, Fe—Ni, Fe—Ni—Mo, or Fe—Si—Al. This is because these metal magnetic materials have high saturation magnetic flux density and magnetic permeability and exhibit excellent soft magnetic characteristics. If the content of at least one of Fe and Ni is 50 wt% or more, the ratio of Fe, Ni, Si, Mo, and Al may be determined as appropriate according to the intended magnetic characteristics.

  It is desirable that the metal magnetic material be magnetically continuous in the magnetic thin body 4. This is to obtain excellent magnetic characteristics.

  In addition, it is desirable that the average particle diameter of the metal magnetic powder used for sheet forming is 0.1 to 100 μm. From the viewpoint of reducing loss, the thickness of the magnetic thin body is preferably 300 μm or less as described below, and in order to realize this thickness, it is preferably at least 100 μm or less. This is because the cost can be reduced by setting the thickness to 0.1 μm or more.

  That is, when it is smaller than 0.1 μm, for example, when it is prepared by an atomizing method, the yield is remarkably lowered. As a method for producing such a fine powder, for example, a wet method using a precipitation reaction in a solution, thermal plasma, The vapor phase method using evaporative solidification can be mentioned, but these methods are expensive.

  The thickness of the magnetic thin body 4 is preferably 0.5 to 300 μm. By making it 300 μm or less, it is possible to suppress eddy currents and to suppress an increase in loss in the high frequency region, and by making it 0.5 μm or more, there is no need to reduce the particle size of the magnetic powder. This is because the cost can be reduced as described above.

  In addition, as shown in FIG. 5, it is desirable to set it as the structure which provides the insulating layer 10 in the magnetic thin body 4. FIG. This is because such a configuration can suppress the eddy current from rotating around the entire core through the magnetic thin bodies, and suppress an increase in loss in the high frequency region.

  In addition, the organic binder used for this invention is not specifically limited, For example, an epoxy resin, an acrylic resin, a butyral resin, a phenol resin etc. can be used. Acrylic resins and butyral resins having good degreasing properties are preferred.

  Here, the manufacturing method of the magnetic thin body 4 in Embodiment 1 of this invention is demonstrated.

  First, a metal magnetic powder and an organic binder are kneaded and dispersed to form a slurry.

  Next, a sheet-like mixture is formed by sheet molding using the obtained slurry.

  Then, the magnetic thin body 4 which has the pore 6 in the sheet | seat 5 which consists of magnetic materials can be manufactured by removing and baking this sheet-like mixture.

  In addition, the kneading | mixing dispersion | distribution process in this invention is not specifically limited, For example, various ball mills, such as a rotation ball mill and a planetary ball mill, can be used. It is also possible to add a plasticizer for the purpose of improving the plasticity of the sheet-like mixture and a solvent for the purpose of adjusting the viscosity of the slurry during kneading and dispersing.

  In addition, the sheet | seat shaping | molding process in this invention is not specifically limited, For example, it can carry out with a column-shaped coating machine etc.

  In addition, the removal process in this invention is not specifically limited, It can carry out using a normal removal furnace. Degreasing conditions may be appropriately determined depending on the organic binder used, and the degreasing temperature is 200 to 500 ° C., and the degreasing time is in the range of 1 to 24 hours.

  In addition, the baking process in this invention is not specifically limited, It can carry out using normal electric furnaces, such as a horizontal furnace, a box furnace, a belt furnace. The firing conditions may be appropriately determined according to the target porosity, the firing temperature is 600 to 1400 ° C., and the firing time is 0.5 to 48 hours. The firing atmosphere is preferably a non-oxidizing atmosphere such as a reducing atmosphere or an inert atmosphere in order to prevent deterioration of magnetic characteristics due to oxidation.

  Specific examples will be described below.

(Example 1)
First, a predetermined amount of metal magnetic powder having an average particle diameter of 18 μm, butyral resin as an organic binder, phthalate ester as a plasticizer, and methyl ethyl ketone as a solvent are kneaded and dispersed in a rotary ball mill to prepare a slurry.

  Next, a sheet-like mixture is formed using this slurry by a doctor blade method.

  Then, the prepared sheet-like mixture is degreased at 300 to 400 ° C. for 3 to 8 hours.

  Next, baking is performed at 850 to 1200 ° C. in an argon atmosphere for 1 to 5 hours.

  Thus, a metal magnetic thin body having a porosity of 20 vol% and a thickness of about 60 μm was prepared.

(Example 2)
First, using a metal magnetic powder having a composition of 3.6 Si 96.4 Fe and an average particle diameter of 25 μm in terms of% by weight, a sheet-like mixture is formed and degreased in the same manner as in Example 1.

  Next, baking is performed at 670 to 1300 ° C. in a hydrogen atmosphere for 1 to 12 hours.

  Thus, a metal magnetic thin body having a porosity of 30 vol% and a thickness of about 90 μm was prepared.

(Example 3)
First, a sheet-like mixture is prepared in the same manner as in Example 1 by using metal magnetic powder having a composition of 49 Ni 51 Fe and an average particle diameter of 12 μm in terms of% by weight.

  Next, the obtained sheet-like mixture is degreased at 350 ° C. for 8 hours.

  Thereafter, baking is performed at 1050 ° C. for 1 hour in a hydrogen atmosphere.

  Thus, a metal magnetic thin body having a porosity of 23% and a thickness of about 35 μm was prepared.

  The magnetic element of the present invention has high direct current superimposition characteristics and is useful in various electric devices.

External perspective view of a conventional magnetic element Sectional view of a conventional magnetic element Sectional drawing of the magnetic thin body in Embodiment 1 of this invention Sectional drawing of the magnetic element in Embodiment 1 of this invention Sectional drawing of the laminated core in Embodiment 1 of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Magnetic body 2 Coil 3 Terminal 4 Magnetic thin body 5 Sheet 6 Porous 7 Laminated core 8 Coil 9 Terminal 10 Insulating layer

Claims (7)

With a sheet of magnetic material,
A magnetic thin body provided with pores in the sheet. The magnetic thin body according to claim 1, wherein the content of pores in the sheet is 3 vol% or more and 50 vol% or less. The magnetic thin body according to claim 1, wherein the magnetic material is a metal magnetic material. Metal magnetic material
The magnetic thin body according to claim 3, comprising at least one of Fe, Fe-Si, Fe-Ni, Fe-Ni-Mo, and Fe-Si-Al. Magnetic bodies formed by laminating magnetic thin bodies according to any one of claims 1 to 4,
A coil for generating a magnetic flux flowing in the magnetic body;
A magnetic element having a terminal electrically connected to the coil; The magnetic element according to claim 5, wherein an insulating layer is provided between the magnetic thin bodies. First, a metal magnetic powder and an organic binder are kneaded and dispersed to create a slurry,
Next, a sheet-like mixture is formed using the slurry,
A method for producing a magnetic thin body, in which the sheet-like mixture is then removed and fired.

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