JP2020094278A - Insulation coating soft magnetic alloy powder - Google Patents

Abstract

To provide a soft magnetic alloy powder that has both of magnetic properties and reliability of insulation, corrosion resistance and the like.SOLUTION: There is provided an insulation coating soft magnetic alloy powder wherein an oxide coat of 1-10 nm in thickness is formed on the surface of iron-based soft magnetic alloy powder, with the ratio between particle size (D50)/oxide coat thickness being 100-21000.SELECTED DRAWING: Figure 1

Description

The present invention relates to an insulating coated soft magnetic alloy powder.

In recent years, for power inductors used in power supply circuits, soft magnetic materials that can be used at large currents and high frequencies have been demanded due to demands for downsizing and height reduction. Conventionally, ferrite-based materials, which are oxides, have been used as the main material of inductors, but they are disadvantageous in downsizing due to their low saturation magnetization. In recent years, alloy-based materials that have high saturation magnetization and are advantageous for downsizing and height reduction The number of metal inductors using materials is increasing rapidly. A soft magnetic alloy powder containing iron as a main material (hereinafter, also referred to as iron-based soft magnetic alloy powder) is used for the metal inductor, and a soft magnetic alloy powder and a resin are mixed, and a powder magnetic core formed by compression molding is used. Are known. The magnetic characteristics (saturation magnetization, magnetic permeability, core loss, frequency characteristics, etc.) of the dust core depend on the magnetic characteristics, particle size distribution, filling property, and electrical resistance of the soft magnetic alloy powder used.

Conventionally used ferrite materials are oxides, so they had high reliability such as insulation and corrosion resistance, but alloy materials have lower reliability than ferrite materials, and soft magnetic alloys As a method of improving the insulating property and corrosion resistance of powder, for example, film formation by phosphoric acid treatment is known (Patent Documents 1 and 2). However, in the case of forming a film by phosphoric acid treatment, the film thickness of the film is as thick as micron order, so the magnetic properties of the powder are deteriorated, and further, the film is easily peeled off by an external force. There is a problem that the characteristics are deteriorated due to the energization of the magnetic material and the generation of rust. In order to achieve both magnetic properties and reliability such as insulation and corrosion resistance, a thinner coating that is difficult to peel off is required.

JP, 2003-272911, A JP, 2008-63651, A

It is an object of the present invention to provide a soft magnetic alloy powder having both high magnetic properties and reliability such as insulation and corrosion resistance.

The present inventor, as a result of various studies, formed a thin oxide film having a nano-order film thickness on the iron-based soft magnetic alloy powder, and as a result, a high insulating property was obtained while suppressing deterioration of magnetic properties. The present invention has been completed based on the finding that an iron-based soft magnetic alloy powder having corrosion resistance (hereinafter also referred to as an insulating coating soft magnetic alloy powder) can be obtained.

That is, in the present invention, an oxide film having a film thickness of 1 to 10 nm is formed on the surface of the iron-based soft magnetic alloy powder, and the particle diameter (D50)/oxide film thickness ratio is 100 to 21000. Which is a soft magnetic alloy powder having an insulating coating.

According to one aspect of the present invention, there is provided the above-mentioned insulating coated soft magnetic alloy powder, wherein the oxide coating has a thickness of 1 to 6 nm.

According to one aspect of the present invention, there is provided the above-described insulating coated soft magnetic alloy powder having a particle diameter (D50)/oxide coating thickness ratio of 150 to 3000.

According to one aspect of the present invention, there is provided the above-mentioned insulating coated soft magnetic alloy powder, wherein the iron-based soft magnetic alloy powder has a particle size (D50) of 0.7 to 5 μm.

According to one aspect of the present invention, there is provided the above-mentioned insulating coated soft magnetic alloy powder, wherein the iron based soft magnetic alloy powder is an iron based amorphous alloy powder or an iron based crystalline alloy powder.

According to one aspect of the invention,
The iron-based soft magnetic alloy powder has the following composition formula:
_{(Fe 1-st Co s Ni} t) 100-xy {(Si a B b) m (P c C d) n} x M y
[Wherein the composition ratio of Fe, Co and Ni is
19≦x≦22,
0≦y≦6.0,
0≦s≦0.35,
0≦t≦0.35, and s+t≦0.35,
The composition ratio of Si, B, P and C is
(0.5:1)≦(m:n)≦(6:1),
(2.5:7:5)≦(a:b)≦(5.5:4.5) and (5.5:4.5)≦(c:d)≦(9.5:0.5) ),
M is Nb or Mo]
There is provided the above-mentioned insulating coated soft magnetic alloy powder which is an iron-based amorphous alloy powder having a composition represented by:

According to one aspect of the present invention, there is provided the above-described insulating coated soft magnetic alloy powder, wherein the iron-based soft magnetic alloy powder is a Fe-Si-Cr-based crystalline alloy powder.

According to one aspect of the present invention, there is provided the above-described insulating coated soft magnetic alloy powder containing 5% by weight or less of Cr.

According to one aspect of the present invention, there is provided the above-mentioned insulating film soft magnetic alloy powder, wherein the oxide film is a SiO ₂ film.

According to the present invention, it is possible to provide a soft magnetic alloy powder having both high magnetic properties and reliability such as insulation and corrosion resistance.

2 is a transmission electron micrograph of the insulating coated soft magnetic alloy powder of the present invention. 3 is a graph showing a scanning electron micrograph of an insulating coated soft magnetic alloy powder and an iron-based amorphous alloy powder on which an oxide coating is not formed, and a line scan result of oxygen by an energy dispersive X-ray analyzer. It is a graph which shows the film thickness of an oxide film, the particle size of an insulating film soft magnetic alloy powder, and the amount of oxygen concerning Comparative Example 5 and Examples 11-17. It is a graph which shows the relationship between the film thickness of an oxide film and the resistivity which concerns on the comparative example 5 and Example 11-17. It is a photograph which shows the presence or absence of rust after a salt spray test concerning an example and a comparative example. It is a graph which shows the relationship between the film thickness of an oxide film and magnetic permeability which concerns on the comparative example 5 and Example 11-17.

Hereinafter, one embodiment of the present invention will be described in detail. The present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within a range that does not impair the effects of the present invention.

In the insulating coated soft magnetic alloy powder according to the present embodiment, an oxide coating having a film thickness of 1 to 10 nm is formed on the surface of the iron-based soft magnetic alloy powder. In the insulating coated soft magnetic alloy powder according to the present embodiment, the oxide coating has a film thickness of 1 to 10 nm, preferably 1 to 9 nm, more preferably 1 to 8 nm, still more preferably 1 to 6 nm. By forming a thin oxide film of nano-order in the above range on the surface of the iron-based soft magnetic alloy powder, the insulating film has a high insulating property while suppressing the deterioration of the magnetic properties of the soft magnetic alloy powder. Corrosion resistance can be obtained.

[Film thickness]
The film thickness of the oxide film of the insulating film soft magnetic alloy powder according to the present embodiment means an actually measured value of the film thickness measured using a transmission electron microscope or the like.

[Oxide coating]
In the present specification, the “oxide coating” means an insulating coating containing an oxide, which is formed in the form of an iron-based soft magnetic alloy powder, and as long as the coating has insulating properties, the oxide is particularly Not limited.

[Iron-based soft magnetic alloy powder]
In the present specification, the "iron-based soft magnetic alloy powder" means a conventionally known soft magnetic alloy powder mainly composed of iron. From the viewpoint of magnetic properties and productivity, the iron-based soft magnetic alloy powder is preferably an iron-based amorphous alloy powder or an iron-based crystalline alloy powder produced by a water atomizing method. The particle size of the iron-based soft magnetic alloy powder is not particularly limited and is adjusted according to desired magnetic characteristics.

[Ratio of particle size (D50)/thickness of oxide film]
In the insulating coated soft magnetic alloy powder according to the present embodiment, the ratio of the particle diameter of the insulating coated soft magnetic alloy powder (D50)/the film thickness of the oxide coating is 100 to 21000, preferably 100 to 10000, and more preferably 150 to. It is 5,000, more preferably 150 to 3,000. The “particle size (D50)/oxide film thickness ratio” is the ratio of the measured value of median diameter D50 of the insulating film soft magnetic alloy powder to the measured film thickness of the oxide film, It is a dimensionless quantity that has no unit. Since the ratio of the particle diameter (D50)/the film thickness of the oxide film is within the above range, the insulating film soft magnetic alloy powder has excellent magnetic properties, insulating properties and corrosion resistance as a material for a dust core. ..
The particle diameter of the iron-based soft magnetic alloy powder according to the present embodiment is preferably 0.1 to 210 μm, more preferably 0.2 to 100 μm, still more preferably 0.5 to 50 μm, and even more preferably 0.5 to 30 μm, particularly preferably 0.7 to 5 μm.

[Particle size]
In the present specification, the “particle diameter” means a median diameter: D50, which is measured by a conventionally known method, for example, a laser diffraction/scattering method.

In the insulating coated soft magnetic alloy powder according to the present embodiment, the iron-based soft magnetic alloy powder is preferably iron-based amorphous alloy powder or iron-based crystalline alloy powder. The use of the iron-based amorphous alloy powder or the iron-based crystalline alloy powder has excellent soft magnetic properties.

In the insulating coated soft magnetic alloy powder according to the present embodiment, the iron-based soft magnetic alloy powder has the following composition formula:
_{(Fe 1-st Co s Ni} t) 100-xy {(Si a B b) m (P c C d) n} x M y
[Wherein the composition ratio of Fe, Co and Ni is
19≦x≦22,
0≦y≦6.0,
0≦s≦0.35,
0≦t≦0.35, and s+t≦0.35,
The composition ratio of Si, B, P and C is
(0.5:1)≦(m:n)≦(6:1),
(2.5:7:5)≦(a:b)≦(5.5:4.5) and (5.5:4.5)≦(c:d)≦(9.5:0.5) ),
M is Nb or Mo]
An iron-based amorphous alloy powder having a composition represented by is preferable.
Since the iron-based soft magnetic alloy powder is the iron-based amorphous alloy powder having the above composition, it has flame retardancy in addition to excellent soft magnetic properties.

The insulating coated soft magnetic alloy powder according to the present embodiment is preferably an iron-based crystalline alloy powder in which the iron-based soft magnetic alloy powder is a Fe-Si-Cr-based crystalline alloy powder. Since the iron-based soft magnetic alloy powder is the Fe-Si-Cr-based crystalline alloy powder, it has excellent soft magnetic characteristics and corrosion resistance.

In the insulating coated soft magnetic alloy powder according to this embodiment, the iron-based soft magnetic alloy powder preferably contains 5 wt% or less of Cr. By containing Cr, an oxide film is formed on the surface of the iron-based soft magnetic alloy powder itself, and the corrosion resistance of the insulating soft magnetic alloy powder is further improved. Not only Cr but also Al, Zn, etc. contribute to the formation of an oxide film on the surface of the iron-based soft magnetic alloy powder itself, and therefore, the same effect is obtained. Since Al has the effect of increasing the hardness of the oxide film formed by Cr and/or Zn and improving the corrosion resistance, a synergistic effect can be obtained by simultaneously including Cr and/or Zn and Al.

In the insulating coated soft magnetic alloy powder according to the present embodiment, the oxide coating is preferably a SiO ₂ film. Since the oxide film is a dense and chemically very stable SiO ₂ film, it is possible to obtain an insulating film soft magnetic alloy powder that is hard to peel off and has high insulation and corrosion resistance.

[Production method]
The insulating coated soft magnetic alloy powder according to the present embodiment is manufactured by forming an oxide coating on the iron-based soft magnetic alloy powder.

The iron-based soft magnetic alloy powder, which is a material, can be manufactured by a conventionally known melting process method, mechanical process method, or chemical process method, but is preferably manufactured by an atomizing method. For the melt in which the material adjusted to the desired composition is melted, the powder is obtained by performing the atomizing method in which the parameters are set so that the desired cooling conditions and the particle size are obtained, and then the powder is dried to obtain the target. An iron-based soft magnetic powder can be obtained. Among the atomizing methods, the water atomizing method is preferable because it can be produced in the atmosphere and thus the equipment cost and the production cost are low and a powder having a small diameter can be obtained. Since the powder has a small diameter, it is possible to suppress eddy current loss and manufacture a dust core or the like having excellent magnetic characteristics.

The oxide film can be formed by a conventionally known method such as a vapor phase method such as a chemical vapor deposition method (CVD) or a physical vapor deposition method (PVD) or a thermal spraying method. From the viewpoint, the sol-gel method is preferred. In the sol-gel method, a solution containing a metal alkoxide or metal acetate as a raw material of an oxide as a film component, water for hydrolysis, an alcohol as a solvent, an acid or a base as a catalyst, and the like as described above. After mixing with the iron-based soft magnetic alloy powder obtained in (1), the solvent is removed by heating to form an oxide film. Mixing can be performed using, for example, a planetary mixer, a mix muller, a raft mixer, a ribbon mixer, or the like, and the device used for mixing is not particularly limited as long as it is a device having a mechanism for mixing powder and solution. .. In the sol-gel method, the film thickness of the oxide film can be adjusted to a desired film thickness by adjusting conditions such as the compounding amount of the oxide, the mixing time, the dropping method of the solution, the dropping amount, and the temperature. it can.

By carrying out classification after forming the oxide film, it is possible to obtain an insulating film soft magnetic alloy powder having a target particle size according to desired magnetic characteristics.

Examples of the present invention will be shown below. The contents of the present invention should not be construed as being limited to these examples.

[Production of soft magnetic alloy powder for insulating film]
1. Preparation of Raw Material Alloy Powder A raw material mixture prepared so as to have the following composition was melted in a high frequency induction furnace, and an iron-based amorphous alloy powder and an iron-based crystalline alloy powder were produced by using a water atomizing method.
<Iron-based amorphous alloy powder>
_{(Fe 1-st Co s Ni} t) 100-xy {(Si a B b) m (P c C d) n} x M y
In the formula, s=0, t=0, x=22, y=0.89, m:n=3:1, a:b=3.8:6.2, c:d=7.8:2. .2 and Cr: 0 wt% to 3.0 wt %.
<Iron-based crystalline alloy powder>
-(92) Fe3.5Si4.5Cr (wt%),
・(95)Fe2Si3Cr(wt%),
・(92)Fe5Si3Cr(wt%),
・(90)Fe7Si3Cr(wt%),
-(92)Fe7Si1Cr (wt%), and-(91)Fe7Si2Cr (wt%)
The conditions of water atomizing in the production of the iron-based amorphous alloy powder and the iron-based crystalline alloy powder were as follows.
<Iron-based amorphous alloy powder-water atomizing conditions>
・Water pressure: 100 MPa
・Water volume: 100 L/min ・Water temperature: 20°C
・Orifice diameter: φ4mm
・Melting temperature: 1500℃
<Iron-based crystalline alloy powder-water atomizing conditions>
・Water pressure: 100 MPa
・Water volume: 100 L/min ・Water temperature: 20°C
・Orifice diameter: φ4mm
・Melting temperature: 1800℃

Each of the obtained iron-based amorphous alloy powder and iron-based crystalline alloy powder was dried by a vibrating vacuum dryer (VU-60 manufactured by Central Processing Machine). The drying conditions are as follows.
<Drying conditions>
・Temperature: 100℃
-Pressure: 10 kPa or less-Time: 60 minutes With respect to each of the iron-based amorphous alloy powder and the iron-based crystalline alloy powder after drying, the composition analysis was performed by an ICP emission spectrometer [SPS3500DD: manufactured by Hitachi High-Tech Science] It was confirmed that it had a composition that

2. Conditions for obtaining a coating solution containing iron-based amorphous alloy powder and iron-based crystalline alloy powder after coating treatment and drying, each having components necessary for forming a SiO ₂ coating, and a target film thickness Was mixed and heated to completely remove the solvent, and at the same time, the oxide film was cured to form oxide films of various thicknesses. The conditions for controlling the film thickness were determined by calculating from the concentration of the coating component of the coating liquid (concentration of the solid component of the coating liquid), the specific gravity of the coating component, and the specific surface area of each powder.
For example, when obtaining an oxide film having a film thickness of 5 nm, 10.98 g of a coating liquid having a concentration of 10% was mixed with 1 kg of each powder.

3. Classifying treatment Coating treatment, iron-based amorphous alloy powder and iron-based crystalline alloy powder after drying, respectively, are classified by an air flow classifier [Nisshin Engineering: Turbo Classifier] to obtain the target insulating coated soft magnetic alloy powder. Obtained. The particle size (D50) of the obtained insulating coated soft magnetic alloy powder was measured by using a wet particle size distribution analyzer [MT3300EX II: manufactured by Microtrac Bell].

Insulating film soft magnetic alloy powder (Example 1-32, Comparative Example 1-16) produced using iron-based amorphous alloy powder, and insulating film soft magnetic alloy powder produced using iron-based crystalline alloy powder (implementation The following evaluations were performed on Examples 33-50 and Comparative Examples 17-28).

[Evaluation item]
1. Powder physical properties
1-1. Film observation Scanning electron microscope (SEM) [JSM7200: made by JEOL] was used to observe the shape of the insulating film soft magnetic alloy powder, and an energy dispersive X-ray analyzer (EDS) [X-MAX50: made by Oxford Instruments ], the oxide film was observed using the transmission electron microscope (TEM) [H-9500: made by Hitachi High-Technologies].
1-2. Oxygen content measurement The oxygen content contained in the insulating coated soft magnetic alloy powder was measured using an oxygen analyzer [EMGA823: manufactured by Horiba, Ltd.].

2. Coating performance Insulating coating Soft magnetic alloy powder and epoxy resin were mixed to produce granulated powder, which was pressed into a cylindrical shape to produce pellets (diameter: 12 mm, height: 5 mm). ..
2-1. Insulation evaluation Withstanding voltage insulation resistance tester [TOS9201: Kikusui Denki], both sides of the pellet were sandwiched between copper plates, the resistance value was measured by the two-terminal method, and the volume resistivity was calculated from the external dimensions and resistance value of the pellet. did.
2-2. Evaluation of Corrosion Resistance Using a salt spray tester [STP-90V-4: manufactured by Suga Test Instruments], a salt spray test was conducted according to American Standard ASTM-B117. The occurrence of rust on the pellet surface was visually checked every 24 hours up to 96 hours.

3. Magnetic properties The above-mentioned granulated powder is pressed into a ring shape (molding pressure: 5 MPa) to produce a dust core (outer diameter: 15 mm, inner diameter: 9 mm, thickness: 3 mm), wire diameter: 0.3 mm The toroidal core in which the copper wire of No. 2 was wound by bi-ferra was prepared and used as the evaluation data. The magnetic permeability was measured using a BH analyzer [SY8258: manufactured by Iwatsu Keisoku] under the conditions of measurement frequency: 1000 kHz and maximum magnetic flux density: 40 mT.

[Evaluation results]
1. Powder Physical Properties FIG. 1 is a transmission electron microscope (TEM) photograph of an insulating coated soft magnetic alloy powder obtained by forming an oxide coating on an iron-based amorphous alloy powder according to Example 16. As shown in FIG. 1, it was confirmed that a film (film thickness: 5 nm) was certainly formed on the iron-based amorphous alloy powder. It was also confirmed that the film thickness calculated from the film treatment conditions of the oxide film and the film thickness actually match.

FIG. 2 is a scanning electron micrograph of an insulating coated soft magnetic alloy powder according to Example 15 (on the right in FIG. 2) and an iron-based amorphous alloy powder without an oxide coating according to Comparative Example 5 (on the left in FIG. 2) ( It is a line scan result of oxygen by a SEM) and an energy dispersive X-ray analyzer (EDS). The vertical axis represents the number of oxygen Kα rays counted per hour, and the higher the value, the more oxygen is present, that is, the oxide film is formed. As is clear from the left-right comparison in FIG. 2, it was confirmed that the oxide film was certainly formed on the iron-based amorphous alloy powder by the film treatment.

FIG. 3 shows the relationship between the film thickness (nm) of the oxide film calculated from the conditions for forming the oxide film, the particle size (D50: μm) of the insulating film soft magnetic alloy powder, and the oxygen amount (wt %). It is an example of the graph shown (Comparative example 5 and Examples 11-17). As shown in FIG. 3, as the film thickness is increased, the amount of oxygen is increased in proportion, which means that the oxide film is formed on the iron-based amorphous alloy powder. It means that the film can be adjusted to a desired film thickness.

2. Film Performance FIG. 4 is an example of a graph showing the relationship between the film thickness and the resistivity of the oxide film of the insulating film soft magnetic alloy powder (Comparative Example 5 and Examples 11-17). The resistivity of the iron-based amorphous alloy powder having no oxide film was about 1.0×10 ⁴ Ω·m, but the resistivity increased about 100 times even if the thickness of the oxide film was 1 nm. However, when the film thickness of the oxide film was 2 nm, the resistivity was as high as about 1.0×10 ⁷ Ω·m.

FIG. 5 is an example of a photograph showing the presence or absence of rust after the salt spray test, in which the black dots in the photograph surrounded by the broken line are the rust. The iron-based amorphous alloy powder having no oxide film has rust after 48 hours. On the other hand, in the iron-based amorphous alloy powder having an oxide film, rust was observed only after 96 hours when the film thickness was 2.5 nm, and when the film thickness was 3 nm, rust was observed even after 96 hours. Was not done. It can be seen that the insulating coated soft magnetic alloy powder according to the present example has significantly improved corrosion resistance even when the oxide coating has a nano-thickness.

3. Magnetic Properties FIG. 6 is an example of a graph showing the relationship between the film thickness of the oxide film and the magnetic permeability (Comparative Example 5 and Examples 11-17). It can be seen that since the thickness of the oxide film is as thin as nano-order, even if the film thickness increases, the decrease in magnetic permeability is small and the decrease in magnetic permeability is moderate.

Table 1 shows the evaluation results of the insulating coating soft magnetic alloy powder (Example 1-32, Comparative Example 1-16) produced by using the iron-based amorphous alloy powder, and the insulation produced by using the iron-based crystalline alloy powder. Table 2 shows the evaluation results of the coated soft magnetic alloy powders (Example 33-50, Comparative Examples 17-28).

In Tables 1 and 2, the "reduction rate (%)" is the reduction rate of the magnetic permeability compared to the alloy powder on which the oxide film not subjected to the film treatment is not formed, and the "corrosion resistance (h)" In the above-mentioned salt spray test, is the result of visually confirming the occurrence of rust every 24 hours, "-48" was the occurrence of rust was confirmed within 48 hours, "48-72" Indicates that rust has been confirmed within 48 hours to 72 hours, "72-96" indicates that rust has occurred within 72 hours to 96 hours, and "96-" indicates that 96 hours have elapsed. It means that the generation of rust was not confirmed.

As shown in Tables 1 and 2, the insulating coated soft magnetic alloy powders according to the examples suppress the decrease rate of magnetic permeability to less than 20% regardless of whether they are amorphous or crystalline. Moreover, the resistivity and the corrosion resistance are improved as compared with the comparative example in which the coating is not formed. In addition, about Examples 11, 24, and 27 in Table 1, the result of corrosion resistance evaluation is "-48" similarly to Comparative Examples 5, 11, and 13, respectively, but compared with Comparative Examples 5, 11, and 13. Since the resistivity was significantly improved, it was clear that the oxide film was indeed formed, and no difference was observed by observation every 24 hours, but the oxide film was not formed. It can be said that the corrosion resistance is improved as compared with the comparative example. From this result, it can be said that the insulating coated soft magnetic alloy powders according to the examples have excellent properties as a material for the dust core. In particular, the insulating coated soft magnetic alloy powder according to Examples 1-9, 11-15, 18, 19, 21, 21, 22, 24, 25, 27, 28, 30, 31 has a decrease rate of magnetic permeability of less than 10%. That is, the insulating coated soft magnetic alloy powders according to Examples 1, 2, 5-9, 14, 15, 19, and 31 further have high resistivity and corrosion resistance. There is. The insulating coated soft magnetic alloy powder according to the example has very excellent characteristics as a material for a dust core.

As shown in Tables 1 and 2, the insulating coated soft magnetic alloy powders according to the examples are formed of an oxide coating on the surface of the iron-based soft magnetic alloy powder itself, and are effective in improving the corrosion resistance of Cr. Even if the content is small, the corrosion resistance is improved. That is, according to the present invention, the amount of Cr used can be reduced and the insulating coated soft magnetic alloy powder can be produced at a lower cost.

In this embodiment, each powder was coated with a SiO ₂ film, but the same result can be obtained by coating with an Al ₂ O ₃ film.

Claims (9)

An oxide film having a film thickness of 1 to 10 nm is formed on the surface of the iron-based soft magnetic alloy powder, and the ratio of particle diameter (D50)/oxide film thickness is 100 to 21000. Magnetic alloy powder. The insulating coated soft magnetic alloy powder according to claim 1, wherein the oxide coating has a thickness of 1 to 6 nm. The insulating coated soft magnetic alloy powder according to claim 1 or 2, wherein a ratio of particle diameter (D50)/oxide coating thickness is 150 to 3000. The insulating coated soft magnetic alloy powder according to claim 1, wherein the iron-based soft magnetic alloy powder has a particle diameter (D50) of 0.7 to 5 μm. The insulating coated soft magnetic alloy powder according to any one of claims 1 to 4, wherein the iron-based soft magnetic alloy powder is an iron-based amorphous alloy powder or an iron-based crystalline alloy powder. The iron-based soft magnetic alloy powder has the following composition formula:
_{(Fe 1-st Co s Ni} t) 100-xy {(Si a B b) m (P c C d) n} x M y
[Wherein the composition ratio of Fe, Co and Ni is
19≦x≦22,
0≦y≦6.0,
0≦s≦0.35,
0≦t≦0.35, and s+t≦0.35,
The composition ratio of Si, B, P and C is
(0.5:1)≦(m:n)≦(6:1),
(2.5:7:5)≦(a:b)≦(5.5:4.5) and (5.5:4.5)≦(c:d)≦(9.5:0.5) ),
M is Nb or Mo]
The insulating coated soft magnetic alloy powder according to claim 5, which is an iron-based amorphous alloy powder having a composition represented by: The insulating coated soft magnetic alloy powder according to claim 5, wherein the iron-based soft magnetic alloy powder is a Fe-Si-Cr-based crystalline alloy powder. The insulating coated soft magnetic alloy powder according to claim 1, containing 5 wt% or less of Cr. The insulating coated soft magnetic alloy powder according to claim 1, wherein the oxide coating is a SiO ₂ film.