KR20140121810A - Magnetic component, and soft magnetic metal powder used therein and manufacturing method thereof - Google Patents

Abstract

The magnetic component such as the inductor and the antenna using the metal magnetic powder has a high complex component of permeability, which is a loss in the GHz band.
1. A soft magnetic metal powder comprising iron as a main component and having an average particle diameter of 300 nm or less and a coercive force (Hc) of 16 to 119 kA / m (200 to 1500 Oe) and a saturation magnetization of 90 A m 2 / And a volume resistivity of 1.0 x 10 < ¹ > OMEGA .cm or more as measured by a four-probe method is 1.0 m < ² > , The loss coefficient at the GHz band can be suppressed to a low level.

Description

TECHNICAL FIELD [0001] The present invention relates to a magnetic component, a soft magnetic metal powder used therefor, and a method of manufacturing the same. BACKGROUND ART [0002]

The present invention relates to a magnetic component used in a high frequency band, a soft magnetic metal powder constituting the magnetic component, and a method of manufacturing the soft magnetic metal powder.

2. Description of the Related Art In recent years, signals used in electronic devices such as cellular phones, notebook PCs, liquid crystal TVs, and the like are becoming higher in frequency. We are already putting the signal of the GHz band into practical use, and the use of the frequency band exceeding 10 GHz in the future is also expected. As the frequency of such devices is increased, it is required to improve performance in a high frequency range even for individual components such as electronic circuits and other passive elements.

In addition, such a device is intended to be used as a mobile device, and its miniaturization and low power consumption are progressing. Therefore, the individual components are required to have characteristics in the high frequency band and low loss. However, among the components constituting the device, the characteristics of the passive device are often determined based on the physical properties of the material, and it is not easy to improve the characteristics in the high frequency band.

For example, a magnetic component such as an inductor or an antenna may have a product characteristic determined by a physical property called a dielectric constant and a magnetic permeability. An inductor is a part that uses magnetic flux flowing in the main body of the part. In order to obtain an inductor that can be used in a high frequency band, it is necessary to develop a magnetic material having not only a magnetic permeability in a high frequency region but also a loss in a high frequency region.

In the case of an antenna, it is necessary to mount an antenna corresponding to a plurality of frequency bands according to advancement of a communication method or technique. In addition, it is desired to make the occupied area of the antenna within the electronic apparatus as small as possible. It is known that the antenna length when receiving a predetermined frequency is in inverse proportion to the 1/2 power of the product of the real part of the permeability and the real part of the permittivity. That is, in order to shorten the antenna length, it is necessary to develop a magnetic material having a high magnetic permeability at a used frequency range. In addition, since the antenna has a small loss, it is most important that a magnetic body having a small loss in a high frequency region is required.

At present, as a magnetic material used for such an inductor or an antenna, a magnetic iron oxide (hereinafter referred to as a "conventional magnetic material") mainly composed of magnetic iron oxide, iron or an alloy thereof represented by ferrite is used. However, there is a problem in that, in a high frequency range of several hundred MHz or more, the loss due to such a magnetic material increases, so that it can not be suitably used. The reason for this is that since the particle diameter is larger than the magnetic domain size, a large hysteresis loss is generated along with the movement of the magnetic wall when the magnetization is reversed, so that the particle diameter is larger than the skin size, Eddy current) loss is generated.

Among such backgrounds, Patent Document 1 proposes nano-order flat particles as metal magnetic particles used in an antenna.

Japanese Patent Application Laid-Open No. 2010-103427

The use of nano-order magnetic particles in a magnetic component used in a high-frequency band is intended to reduce hysteresis loss due to the movement of the magnetic domain wall by inverting the magnetization in a smaller unit than the domain wall is formed. It is also intended to reduce the eddy current loss by making the magnetic particles smaller than the skin size. In other words, it can be considered that the magnetic particles of the nano order have a possibility of obtaining a low-loss magnetic component in the high-frequency band.

However, although the magnetic part using the metal magnetic particles of Patent Document 1 has a lower loss than that of the conventional magnetic material, the value of tan? Representing loss at 1 GHz is 0.18 according to the description of paragraph 0104, and a new low- .

Therefore, it is an object of the present invention to provide a magnetic component having a sufficiently low loss, a soft magnetic metal powder having a nano order for obtaining the same, and a manufacturing method thereof.

The above problem can be solved by forming a magnetic component using a soft magnetic metal powder having a specific constitution.

More specifically, the soft magnetic metal powder is a soft magnetic metal powder,

With iron as the main component,

An average particle diameter of 300 nm or less,

Coercive force (Hc) of 16 to 119 kA / m (200 to 1500 Oe)

Saturation magnetization (saturated magnetization) of 90 A m < 2 > / kg or more,

1.0 g of the soft magnetic metal powder was vertically pressurized to 64 MPa (20 kN)

4 probe having a volume resistivity of 1.0 x 10 < ¹ > OMEGA .cm or more.

Further, the soft magnetic metal powder may further comprise

Wherein the soft magnetic metal powder forms a core / shell structure and the core is a composite of iron or iron-cobalt alloy and the shell comprises at least one of iron, cobalt, aluminum, silicon, rare earth elements (including Y) Oxide.

In addition, the soft magnetic metal powder may be,

The iron-cobalt ratio in the iron-cobalt alloy is Co / Fe = 0.0 to 0.6 in atomic ratio.

The soft magnetic metal powder contains aluminum and has an atomic ratio of the sum of Fe and Co to a total of Al / Fe and Co = 0.01 to 0.30.

In addition, the soft magnetic metal powder may be,

When the soft magnetic metal powder and the epoxy resin were mixed in a mass ratio of 80:20,

Let μ 'be the real part of the complex permeability, μ' be the imaginary part, and tanδ be the loss coefficient (= μ "/ μ '),

Mu] &gt; 1.5 at the frequency of 1 GHz and mu "&lt; 0.5 and tan < 0.15 at the frequency of 2 GHz.

The present invention also provides an inductor and an antenna using the soft magnetic metal powder.

Further, in the method for producing a soft magnetic metal powder of the present invention,

(Including Y) is added by adding an aqueous solution of at least one of aluminum, silicon, a rare earth element (including Y) and magnesium while blowing an oxygen-containing gas into a solution containing iron ions, A precursor forming step of forming a precursor containing at least one of magnesium and magnesium,

A precursor reducing step of reducing the precursor to a metal powder,

And a slow oxidation process in which oxygen is further added to the metal powder obtained in the precursor reduction step to form an oxide film on the surface of the metal powder.

Further, in the above production method, the solution containing the iron ions is an aqueous solution of an iron compound and a cobalt compound.

Further, in the above production method, the precursor obtained in the precursor forming step is characterized by exhibiting a spinel crystal structure by powder X-ray diffraction.

In the above production method, the precursor reduction step is characterized in that the precursor is exposed to a reducing gas at a temperature of 250 ° C to 650 ° C.

In the above manufacturing method, the desulfurizing step is a step of exposing the metal powder to a gas containing oxygen in an inert gas at a temperature of 20 to 150 캜.

According to the soft magnetic metal powder of the present invention, it is possible to obtain a low-loss magnetic component in which μ ', which is the real number of magnetic permeability at 1 GHz, is 1.5 or more and the loss coefficient is 0.15 or less.

Fig. 1 is a diagram illustrating a configuration of an antenna which is a magnetic component of the present invention.
2 is a diagram illustrating the configuration of a coil component that is a magnetic component of the present invention.
3 is a TEM photograph of the soft magnetic powder according to the present invention.
4 is a TEM photograph of the soft magnetic powder according to the present invention.

Hereinafter, the magnetic parts of the present invention and the soft magnetic metal powder used for them and the manufacturing method thereof will be described. However, the present embodiment exemplifies one embodiment of the present invention, and the following contents can be changed without departing from the spirit of the present invention.

The magnetic component of the present invention is constituted by a molded body obtained by compression molding the soft magnetic metal powder of the present invention. Particularly, as an example of magnetic parts, an antenna and a coil part are exemplified.

1 is a view showing an example of an antenna to which a high-frequency magnetic material is applied. The illustrated antenna 10 includes a radiation plate 4 disposed on a conductor plate 1 and a feed point 2 and a shorting plate 3 for supplying power to the radiation plate 4, ) And the radiation plate (4) sandwich the formed body (5) made of the soft magnetic metal powder. By providing such a structure, the wavelength can be shortened and the antenna 10 can be downsized.

Fig. 2 is a view showing an example of a coil part constituted by using a high-frequency magnetic material. The illustrated coil component 12 is constituted by an electrode 6, a flange 7, a winding 8 and a winding core 9. The core 9 as a molding of the soft magnetic metal powder is an elongated columnar rectangular parallelepiped having a rectangular cross section in the short axial direction. The projecting portion 7 has a rectangular parallelepipedic cross section having a larger rectangular cross section than the rectangular cross section of the core 9 and having a thin thickness in the major axis direction of the core 9. The projections 7 may also be formed of a molded body of soft magnetic metal powder.

Next, the soft magnetic metal powder of the present invention will be described in detail.

&Lt; Composition of soft magnetic metal powder &

The soft magnetic metal powder of the present invention is a soft magnetic metal powder which contains Fe (iron) or Fe and Co (cobalt), Al (aluminum), Si (silicon), rare earth element (including Y (yttrium) At least one kind (hereinafter referred to as &quot; Al etc. &quot;) is included.

With regard to the content of Al or the like, the content of Al or the like with respect to the totalization of Fe and Co is set to be 20 at% or less. In the precursor state before the reduction treatment, Fe or Fe and Co are mixed with Al or the like, and then the precursor is reduced to obtain a metal powder. In the reduced metal powder, a large amount of Fe and Co that are likely to be reduced exist in the interior of the particles, and aluminum oxide or the like which is not reduced exists in many of the surfaces of the particles.

Thereafter, the surface of the metal powder is oxidized to form an insulating film containing Al or the like. This increases the electrical resistance of the particles constituting the metal powder and improves the loss based on the eddy current loss and the like when the magnetic component is used. Further, by increasing the amount of Al to be contained, an oxide film containing a large amount of Al can be formed in the surface layer, and the electrical resistance of the particles is increased, so that the eddy current loss can be reduced and tan? In addition, Al, etc., Fe, Fe and Co may remain on the surface.

When Co is contained, the Co content is 0 to 60 at% in terms of the ratio of Co to Fe (hereinafter referred to as &quot; Co / Fe atomic ratio &quot;) in atomic ratio. More preferably 5 to 55 at%, and still more preferably 10 to 50 at%, in terms of the Co / Fe atomic ratio. In such a range, the soft magnetic metal powder has high saturation magnetization and easy to obtain stable magnetic characteristics.

In addition, Al and the like have an effect of preventing sintering and suppress coarsening of particles by sintering at the time of heat treatment. In this specification, Al and the like are treated as one of the &quot; anti-sintering element &quot;. However, Al and the like are non-magnetic components, and if too much is added, the magnetic properties are diluted, which is not preferable. The content of Al or the like with respect to the totalization of Fe and Co is preferably 1 at% to 20 at%, more preferably 3 at% to 18 at%, and still more preferably 5 at% to 15 at%.

<Manufacturing method>

The process for producing the soft magnetic metal powder of the present invention includes a precursor forming step of forming a precursor and a precursor reducing step of reducing the obtained precursor to obtain a soft magnetic metal powder. After the precursor reduction step, an oxidation step for forming an oxide film on the surface of the soft magnetic metal powder may be added to facilitate handling. The precursor formation process is a wet process, and the precursor reduction process and the oxidation process are dry processes.

The precursor forming step is a step of oxidizing an aqueous solution containing an element to be a raw material to obtain an oxide (reaction product), and consequently a particle (precursor) made of an element serving as a raw material.

The precursor reduction step is a step of reducing the precursor to remove oxygen contained in the precursor forming step to obtain a soft magnetic metal powder composed of the element as a raw material. The oxidation step is a step of forming a slight oxide film on the surface of the obtained soft magnetic metal powder. The nano-order (soft magnetic) metal powder has high activity and is easily oxidized at room temperature. When an oxide film is formed on the surface, it can be stably present in air. Each process will be described in detail below.

&Lt; Precursor Forming Step &

In the precursor forming step, a water-soluble iron compound is suitably used as a raw material. As the water-soluble iron compound, iron sulfate, iron nitrate, and ferric chloride can be preferably used, and iron sulfate is more preferably used. The reaction is carried out by allowing an oxygen-containing gas to pass through an aqueous solution of an iron compound or by adding an aqueous solution of an oxidizing agent such as hydrogen peroxide to form an iron oxide.

In the oxidation reaction, it is preferable to carry out the reaction in an environment in which bivalent iron (Fe ^{2 +} ) and trivalent iron (Fe ^{3 +} ) coexist. By allowing coexistence of iron with a different number of valences, it becomes easy to form nuclei, and particles of suitable size can be obtained. Here, the presence ratio of divalent iron and trivalent iron is important for controlling the particle size of the final precursor, and Fe ^{2 +} / Fe ^{3 +} is preferably in the range of 1 to 300 in molar ratio, 150, and more preferably in the range of 15 to 100. [

When Fe ^{2 +} / Fe ^{3 +} is more than 300, the particle size distribution is deteriorated, which is not preferable. When the ratio of Fe ^{2 +} / Fe ^{3 +} is large, the number of nuclei is decreased and the number of particles is decreased, so that the particle size is large. On the other hand, if the ratio of Fe ^{2 +} / Fe ^{3 +} is small, the number of nuclei becomes large and the number of particles increases, so that the particle size becomes small. The trivalent iron may be a trivalent iron compound or may be produced by oxidizing a bivalent iron.

As a raw material, cobalt may be added to iron. As the cobalt material, a water-soluble cobalt compound is preferably used. This is because it reacts in a wet state. As the water-soluble cobalt, cobalt sulfate, cobalt nitrate, cobalt chloride and the like can be preferably used, and cobalt sulfate is more preferably used.

The addition of cobalt is preferably added before forming the nuclei, more preferably added simultaneously with the iron source. It may also be added after deposition of the oxidation reaction.

Oxidation for growing the nucleus is preferably carried out by blowing air or oxygen into the aqueous solution. This is because the flow rate and the flow rate can be easily adjusted, and even if the manufacturing apparatus is enlarged, the oxidation reaction can be uniformly caused in the solution by increasing the outlet port. It may also be oxidized by adding an oxidizing agent.

The raw material may contain aluminum, silicon, rare-earth elements (including Y), and magnesium in addition to iron or iron and cobalt. It is preferable to use a water-soluble compound for such an element. These elements may be added after the addition of iron or iron and cobalt to the reaction vessel, or they may be added during the oxidation reaction to solidify them in the precursor, or they may be added after the oxidation reaction. As the addition method, it is also possible to add at once or continuously.

&Lt; Precursor Reduction Process &

As described above, the precursor obtained through the wet process is subjected to the dry process. In the precursor reduction step, the precursor is heated and reduced by exposing it to a reducing gas such as carbon monoxide, acetylene, or hydrogen at a temperature of 250 ° C to 650 ° C. At this time, multistage reduction may be performed. The multi-stage reduction refers to performing the reducing process of holding the object to be processed at a predetermined temperature for a predetermined time several times while changing the temperature. By appropriately controlling the temperature and time to be held, the characteristics of the finished metal magnetic powder can be controlled. It is also preferable to use a gas obtained by adding steam to the reducing gas as the atmosphere for the reducing treatment.

<Seosanification process>

An alloy magnetic particle powder is obtained after heating and reduction, but if it is handled in the air as it is, it is likely to be oxidized rapidly. Therefore, an oxide layer is formed by the following oxidation step. The oxidation step is a step of forming an oxide layer on the particle surface by gradually processing the inert gas in an inert gas at a temperature of 20 to 300 DEG C for a predetermined time. In practice, it is preferable that the powder after the reduction is cooled to a temperature at which the oxidation step is carried out and the oxidation is carried out at that temperature. At this temperature, an oxide layer And stabilization treatment is preferably performed. Among these steps, a weakly oxidizing gas of the oxidation treatment may be added with steam, or a dense film may be formed by adding water vapor, which is preferable.

The soft magnetic metal powder thus obtained after the oxidation step was examined for powder characteristics and composition by the following method.

<Average particle diameter>

The average particle diameter was measured using a transmission electron microscope (JEM-100CXMark-II type, manufactured by JEOL Ltd.), and the image obtained by observing the metallic magnetic powder in bright field at an acceleration voltage of 100 kV , Magnification: 58000 times). The photograph was taken (for example, the magnification of the magnification was 9 times), 300 particles randomly dispersed from a plurality of photographs were randomly selected, and the particle diameter was measured for each particle , And the average value was obtained.

<BET specific surface area>

The BET specific surface area was determined by the BET method using 4 Soves US manufactured by Infosysonics KK.

&Lt; Evaluation of magnetic properties and weatherability of soft magnetic metal powder &

The coercive force Hc (Oe and kA / m) was measured at an external magnetic field of 10 kOe (795.8 kA / m) using a VSM apparatus (VSM-7P) manufactured by Dohide Kogyo Co., m), saturation magnetization sigma s (Am &lt; 2 &gt; / kg) and squareness ratio SQ were measured. As an index (? S) for evaluating the weatherability of the soft magnetic metal powder, the soft magnetic metal powder was held in a constant temperature and humidity container having a set temperature of 60 占 폚 and a relative humidity of 90% for one week to measure the saturation magnetization ? s was measured and calculated according to? s after storage (? s after storage) /? s before storage (100%).

<Composition analysis of soft magnetic metal powder particles>

The composition of the soft magnetic metal powder particles was obtained by carrying out mass analysis of the whole particles including the metal magnetic phase and the oxide film. Quantitative determination of Co, Al, Y, Mg, and Si was performed using a high frequency induction plasma emission spectrometer ICP (IRIS / AP) manufactured by Jarrels AS. In addition, the amount of Fe was measured using a Hirunuma automatic titration apparatus (COMTIME-980) manufactured by Hiranuma Industrial Co., In addition, oxygen was quantified using a NITROGEN / OXYGEN DETERMETER (TC-436 type) manufactured by LECO Corporation. Since this quantitative result is given as mass%, the Co / Fe atomic ratio and the Al / (Fe + Co) atomic ratio are obtained by appropriately converting to atomic% (at%).

&Lt; Measurement of volume resistivity of soft magnetic metal powder &

The volume resistivity of the soft magnetic metal powder was measured using a powder resistance measuring unit (MCP-PD51) manufactured by Mitsubishi Chemical Corporation, Inc. and MCP-PDLGPWIN manufactured by MITSUBISHI CHEMICAL ANALYTECHNIC CO., LTD. 1.0 g was measured with a 4-probe method while being vertically pressurized to 64 MPa (20 kN).

&Lt; Preparation of molded article of soft magnetic metal powder &

The obtained soft magnetic metal powder is kneaded together with a resin to obtain a molded article. As the resin used at this time, any known thermosetting resin can be used. As the thermosetting resin, phenol resin, epoxy resin, unsaturated polyester resin, isocyanate compound, melamine resin, urea resin, silicone resin and the like can be selected. As the epoxy resin, any of a monoepoxy compound and a polyvalent epoxy compound or a mixture thereof is used.

Examples of the monoepoxy compounds include butyl glycidyl ether, hexyl glycidyl ether, phenyl glycidyl ether, aryl glycidyl ether, para-tert-butylphenyl glycidyl ether, ethylene oxide, propylene oxide, para Xylyl glycidyl ether, glycidyl acetate, glycidyl butyrate, glycidyl hexoate, and glycidyl benzoate.

Examples of the polyvalent epoxy compound include bisphenol A, bisphenol F, bisphenol AD, bisphenol S, tetramethyl bisphenol A, tetramethyl bisphenol F, tetramethyl bisphenol AD, tetramethyl bisphenol S, tetrabromobisphenol A, Bisphenol type epoxy resins obtained by glycidylating bisphenols such as bisphenol A and tetrafluorobisphenol A; other divalent phenols such as biphenol, dihydroxynaphthalene and 9,9-bis (4-hydroxyphenyl) Tris (4-hydroxyphenyl) methane, 4,4- (1- (4- (1- (4-hydroxyphenyl) -1-methylethyl) Phenyl) ethylidene) bisphenol; epoxy resins obtained by glycidylating tetrakisphenols such as 1,1,2,2, -tetrakis (4-hydroxyphenyl) ethane; Phenol novolak, cresol novolak, bisphenol A novolac, brominated Novolak type epoxy resins obtained by glycidylation of novolacs such as novolac, novolac, novolac, novolac, novolac, novolac, novolac, novolac, novolac and novolac bromoborate, glycidylated polyhydric phenols, glycidyl, polyethylene glycol and other polyhydric alcohols Ether-type epoxy resins obtained by glycidylating hydroxycarboxylic acids such as p-oxybenzoic acid and? -Oxynaphthoic acid, ester-type epoxy resins obtained by glycidylating polycarboxylic acids such as phthalic acid and terephthalic acid Epoxy resins such as glycidylates of amine compounds such as 4,4-diaminodiphenylmethane and m-aminophenol, glycidyl type epoxy resins such as amine type epoxy resins such as triglycidyl isocyanurate, And alicyclic epoxides such as 3,4-epoxycyclohexylmethyl-3 ', 4'-epoxycyclohexanecarboxylate and the like.

Among the epoxy resins described above, a polyhydric epoxy compound is preferable from the viewpoint of enhancing storage stability. Of the polyvalent epoxy compounds, glycidyl type epoxy resins are preferable because of their high productivity, and more preferably epoxy resins obtained by glycidylating polyhydric phenols are preferable because of excellent adhesiveness and heat resistance of cured products . More preferably, the epoxy resin is preferably a bisphenol-type epoxy resin, and more preferably an epoxy resin obtained by glycidylating an epoxy resin glycidylated with bisphenol A and bisphenol F.

It is preferable that the form of the resin is a liquid phase. In terms of keeping the composition solid, the epoxy equivalent is preferably 300 or more.

The mixing ratio of the soft magnetic metal powder and the epoxy resin is preferably from 30/70 to 99/1, more preferably from 50/50 to 95/5 by mass ratio, more preferably from 70/70 to 99/5, / 30 to 90/10. If the amount of the resin is too small, the molded article will not be formed. If the resin is too much, desired magnetic properties can not be obtained.

The soft magnetic metal powder of the present invention can be formed into an arbitrary shape by compression molding. The supply for practical use has a shape as illustrated in Figs. 1 and 2. However, in the following embodiments, the molded article was formed into a donut shape, and the characteristics as a magnetic component were evaluated.

The soft magnetic metal powder and the epoxy resin were weighed at a weight ratio of 80:20 and dispersed in an epoxy resin using a vacuum stirring / defoaming mixer (V-mini300, manufactured by EME Co., Ltd.) to obtain a paste. This paste was dried on a hot plate at 60 DEG C for 2 hours to obtain a soft magnetic metal powder-resin composite. This composite was disintegrated to prepare a powder of the composite. 0.2 g of the composite powder was placed in a donut-shaped container and a load of 1 t was applied by a hand press machine to form a toroidal shaped article having an outer diameter of 7 mm and an inner diameter of 3 mm .

&Lt; Evaluation of high-frequency characteristics of soft magnetic metal powder-resin composite &

(E8362C) manufactured by Ajient Technology Co., Ltd. and the same axial type S-parameter method sample holder kit (manufactured by Kanto Electronics Application Development Co., Ltd.) as a high-frequency property of the molded product of the soft magnetic metal powder- (Μ ') of magnetic permeability at 0.5 to 3 GHz, an imaginary part of magnetic permeability (μ ") and a tan δ representing a loss coefficient are calculated using the following formula: CSH2-APC7, sample size: φ7.0 mm-φ3.04 mm × 5 mm Respectively.

Example

[Example 1]

The precursor forming process was performed as follows. 3000 mL of pure water and 100 mL of sodium hydroxide of 12 mol / L were added to a 5000 mL beaker and stirred while maintaining the temperature at 40 ° C in the early stage. To this was added 900 mL of a solution of 2 mol / L ferric sulfate (special reagent) solution and 1 mol / L ferrous sulfate (special reagent) aqueous solution in a mixing ratio of Fe ^{2 +} / Fe ^{3 +} = 20.

Thereafter, the temperature was raised to 90 占 폚, air was further passed through at 200 mL / min, and oxidation was continued for 40 minutes. After air was converted to nitrogen, the mixture was aged for 10 minutes. Then, 80 ml of 0.3 mol / L aluminum sulfate (a special reagent) was added, and the oxidation was continued for 50 minutes by passing air at 200 mL / min to complete the oxidation. Thus, a precursor particle in which Al was solid-dissolved in Fe was obtained. This precursor was filtered and washed by a conventional method, and then dried at 110 ° C to obtain a dried solid (also referred to as a precursor powder) of the precursor.

Next, a precursor reduction process was performed. The precursor powder in which Al was solid-dissolved in Fe was charged into a ventable bucket, the bucket was charged into a through-type reduction furnace, and reduction treatment was performed at 500 占 폚 for 60 minutes while passing hydrogen gas. After the reduction treatment was finished, metallic iron powder (soft magnetic metal powder) was obtained.

Thereafter, in order to proceed to the oxidation step, the atmosphere in the furnace was changed from hydrogen to nitrogen, and the furnace temperature was lowered to 80 占 폚 at a cooling rate of 20 占 폚 / min while flowing nitrogen. In the oxidation step, in the initial stage of the oxide film formation, a gas mixed at a mixing ratio of 1/125 of the air amount for N ₂ is added into the furnace so that the metal iron powder is not rapidly oxidized, and an oxide film And the oxygen concentration in the atmosphere was increased by gradually increasing the supply amount of air.

The flow rate of the finally supplied air was set to 1/25 of N ₂ . At that time, the total amount of gas introduced into the furnace was kept almost constant by adjusting the flow rate of nitrogen. This decarburization treatment was carried out in an atmosphere maintained at 80 캜.

Thus, a final soft magnetic metal powder (having a surface oxide film) was obtained. Table 2 shows the physical properties and bulk characteristics of the obtained soft magnetic metal powder and the high frequency characteristics of the molded body using the same. The conditions of the composition and precursor reduction process and the oxidation process are shown in Table 1 including other examples.

[Example 2]

3000 mL of pure water and 100 mL of sodium hydroxide of 12 mol / L were added to a 5000 mL beaker, and the mixture was stirred while being kept at 40 캜 in an early stage. This a 1 mol / L of ferrous sulfate (reagent) solution and 1 mol / L of cobalt sulfate (reagent) was added 4: the solution was mixed in a mixing ratio of 1 900 mL, and also (Fe ^{2 + +} Co ^{2 +} ) / Fe ^{3 +} = 20 was added at the same time to the reaction solution of 2 mol / L ferric sulfate (special reagent). Thereafter, the same procedure as in Example 1 was repeated to obtain a soft magnetic metal powder (a portion of Fe having a surface oxide film substituted with Co). Table 2 shows the physical properties and bulk characteristics of the obtained soft magnetic metal powder and the high frequency characteristics of the molded body using the same.

[Example 3]

In Example 2, the same procedure as in Example 2 was repeated except that the mixing ratio of 1 mol / L of ferrous sulfate (special reagent) aqueous solution to 1 mol / L of cobalt sulfate (special reagent) solution was changed to 8: 5 did. Table 2 shows the physical properties and bulk characteristics of the obtained soft magnetic metal powder and the high frequency characteristics of the molded body using the same.

Here, the first to third embodiments will be discussed. Compared with Example 1, which did not contain Co, Examples 2 and 3 containing Co resulted in a higher μ '. When Co is added to the FeCo alloy, the magnetic moment is increased to increase the saturation magnetization, thereby increasing the magnetic permeability. That is, when Co is added, there is an effect of increasing μ '.

In addition, although the resonance frequency is shifted to the low-frequency side and the tan delta tends to worsen (increase) when the value of mu 'increases, in this embodiment, the result of increasing the amount of Co and deteriorating the tan delta . For this reason, by containing Co, a denser oxide film can be formed, so that the volume resistivity of the powder is increased and the eddy current loss can be reduced. That is, by containing Co, it was found that there is an effect of improving μ 'without deteriorating (increasing) tan δ.

[Example 4]

In Example 2, the amount of Fe ^{3 +} to form a tablet core (Fe ^{2 + +} Co ^{2 +)} / Fe ^{3 + =} change to 33, and further the aluminum of 0.3mol / L sulfuric acid is added during the oxidation reaction (reagent ) Was changed to 45 ml, the same procedure as in Example 2 was repeated. Table 2 shows the physical properties and bulk characteristics of the obtained soft magnetic metal powder and the high frequency characteristics of the molded body using the same.

[Examples 5 to 8]

With respect to Examples 5 to 8, the same procedure as in Example 4 was repeated except that the amount of aluminum sulfate was changed to the amount shown in Table 1 in Example 4. Table 2 shows the physical properties and bulk characteristics of the obtained soft magnetic metal powder and the high frequency characteristics of the molded body using the same.

Here, the fourth to eighth embodiments will be discussed. By increasing the amount of Al to be contained, it was found that the effect of decreasing tan? In the present invention, when a precursor containing Fe, Co and Al is reduced, Fe and Co, which are easily reduced, are present in the inside of the particle and aluminum oxide, which is difficult to reduce, is present on the surface of the particle. . Therefore, if the amount of Al to be contained is large, an oxide film containing a large amount of aluminum oxide is formed by the surface of the particles, so that the volume resistivity of the particles is increased, and eddy current loss is reduced and tan?

A TEM photograph of the powder obtained in Example 7 is shown in Fig. The TEM image was obtained by applying an acceleration voltage of 100 kV, and the contrast was adjusted so that the portion of the core appeared black. As a result, in Fig. 3 shown as a confirmed example, there is a globular portion darkened at the center of the approximately spherical particle, and a portion where the periphery thereof is thin and almost transparent is seen. As shown in the photograph, the soft magnetic metal powder obtained by the present invention is formed in a shell portion formed of a core portion formed of a metal and an oxide film.

The composition of the core / shell particles can be analyzed by, for example, ICP emission analysis, ESCA, TEM-EDX, XPS, SIMS and the like. Particularly, according to ESCA, the change in composition from the particle surface to the depth direction can be confirmed, and the core portion formed of metal and the shell portion formed of oxide can be identified. In addition, according to TEM-EDX, particles are irradiated with EDX, and the EDX is irradiated to determine the substitution composition of the particles by semi-quantitative determination, so that it is possible to identify the core portion formed of a metal and the shell portion formed of an oxide For example, Japanese Patent Laid-Open Publication No. 2006-128535 [paragraph [0078], etc.).

[Examples 9 to 10]

With respect to Examples 9 to 10, the same procedure as in Example 8 was repeated except that the reducing temperature was changed to the temperature shown in Table 1 in Example 8. Table 2 shows the physical properties and bulk characteristics of the obtained soft magnetic metal powder and the high frequency characteristics of the molded body using the same.

Here, in Examples 7, 9, and 10, it was found that although the reduction temperature of the precursor is different, the value of μ 'is increased as compared with the embodiment where the reduction temperature is high. The reason for this is believed to be the reduction of Fe and the alloying of Co by accelerating the reduction temperature.

[Example 11]

In Example 2, the same procedure as in Example 2 was repeated except that the reduction temperature by the hydrogen gas in the through-type reduction furnace was changed to 600 캜. Table 2 shows the physical properties and bulk characteristics of the obtained soft magnetic metal powder and the high frequency characteristics of the molded body using the same.

[Example 12]

In Example 11, the same procedure as in Example 11 was repeated except that the amount of Fe ^{3 +} for forming the nuclei was changed to (Fe ^{2 +} + Co ^{2 +} ) / Fe ^{3 +} = 85. The physical properties and the bulk characteristics of the obtained soft magnetic metal powder are shown in Table 2, the high frequency characteristics of the molded body using the same, and the TEM photograph of the obtained powder are shown in Fig. It is also seen from this photograph that the soft magnetic metal powder obtained by the present invention is formed in a shell portion formed of a core portion formed of a metal and an oxide film.

[Comparative Example 1]

As the soft magnetic metal powder of Comparative Example 1, a commercially available Mn-Zn ferrite powder was used. The physical properties and bulk characteristics of the soft magnetic metal powder are shown in Table 2, and the high frequency characteristics of the molded body using the same are shown in Table 3.

[Comparative Example 2]

As the soft magnetic metal powder of Comparative Example 2, a commercially available Fe-Cr-Si powder was used. The physical properties and bulk characteristics of the soft magnetic metal powder are shown in Table 2, and the high frequency characteristics of the molded body using the same are shown in Table 3.

(Industrial availability)

The soft magnetic metal powder of the present invention can be used not only for inductors and antennas but also for soft magnetic applications such as magnetic heads, lower layer materials of magnetic recording media, iron cores of electromagnets, trans cores, antennas, electromagnetic shielding materials and radio wave absorbers.

1: conductor plate
2: feeding point
3: Short plate
4: Radiation plate
5: molded article
6: Electrode
7:
8: Winding
9: Reason
10: Antenna
11: Coil
12: Coil parts

Claims (12)

A soft magnetic metal powder comprising iron as a main component:
An average particle diameter of 300 nm or less,
A coercive force (Hc) of 16 to 119 kA / m (200 to 1500 Oe)
A saturation magnetization of 90 A m &lt; 2 &gt; / kg or more,
1.0 g of the soft magnetic metal powder was vertically pressurized to 64 MPa (20 kN)
4 A soft magnetic metal powder having a volume resistivity of 1.0 × 10 ¹ Ω · cm or more as measured by a probe method.
The method according to claim 1,
Wherein the soft magnetic metal powder forms a core / shell structure and the core is a composite of iron or iron-cobalt alloy and the shell comprises at least one of iron, cobalt, aluminum, silicon, rare earth elements (including Y) Oxide, soft magnetic metal powder.
3. The method of claim 2,
The iron-cobalt ratio in the iron-cobalt alloy is Co / Fe = 0.0 to 0.6 in atomic ratio.
4. The method according to any one of claims 1 to 3,
Wherein the soft magnetic metal powder contains aluminum and has a total atomic ratio of Fe to Co and a sum of Al / Fe and Co = 0.01 to 0.30.
5. The method according to any one of claims 1 to 4,
When the soft magnetic metal powder and the epoxy resin were mixed in a mass ratio of 80:20,
The real part of the complex permeability is denoted by μ ', the imaginary part is denoted by μ', and the loss coefficient is denoted by tan δ (= μ "/ μ '
Mu] &gt; 1.5 at a frequency of 1 GHz and mu "&lt; 0.5 and tan < 0.15 at a frequency of 2 GHz and mu '&gt; 1.5 at a frequency of 2 GHz.
An inductor formed by using the soft magnetic metal powder according to any one of claims 1 to 5.
An antenna formed by using the soft magnetic metal powder according to any one of claims 1 to 5.
(Including Y) is added by adding an aqueous solution of at least one of aluminum, silicon, a rare earth element (including Y) and magnesium while blowing an oxygen-containing gas into a solution containing iron ions, A precursor forming step of forming a precursor containing at least one of magnesium and magnesium,
A precursor reduction step of reducing the precursor to a metal powder,
Wherein the metal powder obtained by the precursor reduction process is further subjected to oxygen to further form an oxide film on the surface of the metal powder.
9. The method of claim 8,
Wherein the solution containing the iron ions is an aqueous solution of an iron compound and a cobalt compound.
10. The method according to claim 8 or 9,
Wherein the precursor obtained in the precursor forming step exhibits a spinel type crystal structure by a powder X-ray diffraction method.
11. The method according to any one of claims 8 to 10,
Wherein the precursor reducing step exposes the precursor to a reducing gas at a temperature of 250 ° C to 650 ° C.
The method according to any one of claims 8 to 11,
Wherein the step of exposing the metal powder is a step of exposing the metal powder to a gas containing oxygen in an inert gas at a temperature of 20 ° C to 150 ° C.

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