Soft magnetic metal powder

Abstract

This soft magnetic metal powder has a high spheronization rate and excellent magnetic characteristics, and contains Fe, Co, and Ni.　Provided is soft magnetic metal powder containing Fe, Co, and less than 5 mol% (excluding 0 mol%) of Ni. The spheronization rate of the soft magnetic metal powder is 75% or more as calculated by the formula: (area / minimum circumscribed circle area) × 100. The soft magnetic metal powder has a crystallite diameter larger than 30 nm. The soft magnetic metal powder has an average particle diameter of 0.05-1.5 μm.

Description

soft magnetic metal powder

[0001] The present disclosure relates to soft magnetic metal powders.

[0002] In recent years, miniaturization and high integration of electronic components such as inductors, magnetic cores, and magnetic heads have been required to improve device performance. Among soft magnetic metal powder materials, alloys containing iron and cobalt are particularly characterized by high saturation magnetic flux density. Therefore, demand for soft magnetic metal powder materials is expected to grow further in the future.

[0003] Increasing the packing density of soft magnetic metal powder is also effective in improving the magnetic properties of electronic components, making soft magnetic metal powder with submicron particle sizes important.

[0004] Furthermore, in response to the demand for thinner electronic components, inductors and transformers are becoming thinner, and for this reason, spherical soft magnetic metal powder containing fine particles is considered ideal.

[0005] Current common methods for producing soft magnetic metal powders include water atomization, gas atomization, and spray pyrolysis. However, all of these methods only produce soft magnetic metal powders with a wide particle size distribution due to the manufacturing process. Furthermore, it is difficult to obtain spherical FeCo-based fine particles.

[0006] JP 2013-236021 A JP 2022-138129 A

[0007] Patent Document 1 discloses a technique for soft magnetic metal powder containing an FeCo alloy. However, the soft magnetic metal powder obtained is not spherical. Therefore, this soft magnetic metal powder is not suitable for use in small electronic devices.

[0008] Patent Document 2 discloses a technique for soft magnetic metal powder containing an iron-nickel alloy. However, the Ni content is high, at 5 mol % or more, and therefore sufficient saturation magnetization characteristics cannot be obtained.

[0009] The above technical problems are solved by the soft magnetic metal powder according to the present disclosure as follows.

[0010] The soft magnetic metal powder according to the present embodiment contains at least Fe, Co, and less than 5 mol % (excluding 0 mol %) of Ni.

[0011] The soft magnetic metal powder of embodiment 1 may have a sphericity of 75% or more. Here, the sphericity is calculated by the following (Equation 1). (Embodiment 2) (Equation 1) Sphericity = (Area / Area of ​​smallest circumscribed circle) × 100

[0012] The soft magnetic metal powder of embodiment 1 may have a crystallite diameter of greater than 30 nm.

[0013] The soft magnetic metal powder of the first embodiment may have an average particle size of 0.05 μm or more and 1.5 μm or less.

[0014] The soft magnetic metal powder of embodiment 1 may have a coefficient of variation of 0.25 or less. Here, the coefficient of variation is calculated by the following (Equation 2): (Embodiment 5) (Equation 2) Coefficient of variation = Standard deviation of particle diameter / Average particle diameter

[0015] The soft magnetic metal powder of the first embodiment may be coated with a compound containing one or more elements selected from aluminum, silicon, chromium, zirconium, titanium, yttrium, and phosphorus.

[0016] According to this embodiment, a soft magnetic metal powder having a high saturation magnetization (σs) can be obtained. In the soft magnetic metal powder according to this embodiment, the Ni content is reduced. Meanwhile, the proportions of Fe and Co are high. Therefore, due to its excellent magnetic properties, this soft magnetic metal powder can be suitably used in the manufacture of electronic components.

[0017] The soft magnetic metal powder according to this embodiment contains Fe, Co, and Ni. Furthermore, the Ni content is less than 5 mol%. This allows for the production of soft magnetic metal powder having a spherical particle shape. Therefore, when this soft magnetic metal powder is used to manufacture electronic components such as inductors, the soft magnetic metal powder exhibits excellent packing properties and thin film smoothness.

[0018] This embodiment will be described in detail below.

[0019] First, the soft magnetic metal powder according to this embodiment will be described.

[0020] The soft magnetic metal powder according to this embodiment contains at least iron (Fe), cobalt (Co), and nickel (Ni). As described above, the soft magnetic metal powder according to this embodiment contains Fe, Co, and Ni, and therefore exhibits the magnetic properties required for electronic components.

[0021] The Ni content of the soft magnetic metal powder according to this embodiment is greater than 0 mol% and less than 5 mol%. In this disclosure, mol% refers to the ratio of the amount of a specific element to the amount of all elements constituting the soft magnetic metal powder.

[0022] When the Ni content is 5 mol% or more, the relative contents of Fe and Co decrease. Therefore, sufficient saturation magnetization may not be obtained. Also, when the Ni content is 0 mol%, that is, when the soft magnetic metal powder contains an alloy of Fe and Co, it may not be possible to obtain a soft magnetic metal powder having a spherical particle shape. The Ni content is preferably 4 mol% or less, more preferably 3 mol% or less. The lower limit of the Ni content is not particularly limited. The Ni content is preferably 0.001 mol% or more, more preferably 0.005 mol% or more.

[0023] The Fe content of the soft magnetic metal powder according to this embodiment is not particularly limited. The Fe content is preferably 70 to 90 mol%, more preferably 71 to 85 mol%, and even more preferably 72 to 80 mol%. If the Fe content is within the above range, electronic components having high saturation magnetization can be produced using the soft magnetic metal powder according to this embodiment.

[0024] The Co content of the soft magnetic metal powder according to this embodiment is not particularly limited. The Co content is preferably 9 to 25 mol%, more preferably 13 to 23 mol%, and even more preferably 15 to 20 mol%. If the Co content is within this range, a higher saturation magnetization can be obtained.

[0025] In order to suppress a decrease in saturation magnetization due to the oxide film, the oxygen (O) content in the soft magnetic metal powder is preferably 13.5 mol % or less, more preferably 10.0 mol % or less, and even more preferably 8.0 mol % or less.

[0026] The soft magnetic metal powder according to this embodiment may contain phosphorus (P). The P content is preferably 5 mol% or less. If the P content exceeds 5 mol%, the proportion of magnetic elements decreases. Therefore, σs decreases. As a result, sufficient magnetic properties of the soft magnetic metal powder may not be obtained. The soft magnetic metal powder according to this embodiment does not necessarily need to contain P. Therefore, the lower limit of the P content is 0 mol%.

[0027] The soft magnetic metal powder according to this embodiment may contain boron (B). The B content is preferably 1.5 mol% or less. If the B content exceeds 1.5 mol%, the proportion of magnetic elements decreases. Therefore, σs decreases. As a result, sufficient magnetic properties of the soft magnetic metal powder may not be obtained. The soft magnetic metal powder according to this embodiment does not necessarily need to contain B. Therefore, the lower limit of the B content is 0 mol%.

[0028] The soft magnetic metal powder according to this embodiment preferably has a spherical particle shape.

[0029] To determine the sphericity in this embodiment, the soft magnetic metal powder according to this embodiment is photographed at 20,000x magnification using a scanning electron microscope (SEM). For all particles present within the field of view of the obtained image, the particle area and the area of ​​the smallest circumscribing circle of the particle are measured using image analysis software A-zo-kun. From the obtained measurements, the sphericity can be calculated using the following (Equation 1): (Equation 1) Sphericity = (Area / Area of ​​smallest circumscribing circle) x 100

[0030] The sphericity of the soft magnetic metal powder according to this embodiment is preferably 75% or more. If the sphericity is 75% or more, when the soft magnetic metal powder according to this embodiment is dispersed in a medium such as a resin, the viscosity of the resulting paste tends to be low. Furthermore, when a thin layer is formed using the paste, the smoothness of the thin layer surface tends to be high.

[0031] In addition, increasing the sphericity of the soft magnetic metal powder improves the fillability of the soft magnetic metal powder in a medium such as a resin, thereby improving magnetic properties such as magnetic permeability and reducing core loss.

[0032] The sphericity is more preferably 77% or more, and even more preferably 80% or more. The upper limit of the sphericity is 100%. A sphericity of 100% means that the powder particles are truly spherical.

[0033] The crystallite diameter of the soft magnetic metal powder according to this embodiment is preferably greater than 30 nm. If the crystallite diameter is 30 nm or less, sufficient magnetic properties may not be obtained. The crystallite diameter is more preferably 40 nm or more, and even more preferably 50 nm or more. The upper limit of the crystallite diameter depends on whether or not annealing treatment is performed. Therefore, the upper limit of the crystallite diameter is not particularly limited. The crystallite diameter is preferably 500 nm or less, and more preferably 300 nm or less.

[0034] The average particle size of the soft magnetic metal powder according to this embodiment is preferably 0.05 μm or more and 1.5 μm or less (0.05 to 1.5 μm), more preferably 0.07 to 1.0 μm, and even more preferably 0.1 to 0.8 μm. If the average particle size is less than 0.05 μm, the proportion of the oxide film on the particle surface increases. As a result, the saturation magnetization may decrease. On the other hand, if the average particle size is greater than 1.5 μm, sufficient thin layer surface smoothness may not be obtained.

[0035] The coefficient of variation of the soft magnetic metal powder according to this embodiment, calculated by the following (Equation 2), is preferably 0.25 or less, more preferably 0.20 or less, and even more preferably 0.18 or less. If the coefficient of variation is within the above range, a narrow particle size distribution can be obtained. As a result, when the layer is thinned, the surface has excellent smoothness. If the coefficient of variation of the soft magnetic metal powder according to this embodiment exceeds 0.25, when a sintered body obtained from the metal powder is used in a small electronic component, sufficient magnetic properties may not be obtained. (Equation 2) Coefficient of variation = Standard deviation of particle size / Average particle size

[0036] The lower limit of the coefficient of variation is, for example, 0.001.

[0037] The soft magnetic metal powder according to this embodiment is preferably coated with a compound containing one or more elements selected from aluminum, silicon, chromium, zirconium, titanium, yttrium, and phosphorus, because this is expected to improve the insulating effect of the soft magnetic metal powder.

[0038] The compound that coats the soft magnetic metal powder particles is not particularly limited. A preferred compound is a metal oxide. Examples of such metal oxides include silicon oxide and aluminum oxide.

[0039] The content of the compound that coats the soft magnetic metal powder particles is not particularly limited, and the preferred content of the compound is in the range of 0.1 mol % to 5.0 mol %.

[0040] If the content of the compound that coats the soft magnetic metal powder particles is less than 0.1 mol %, a sufficient insulating effect may not be obtained, whereas if the content is more than 5.0 mol %, the saturation magnetization may decrease.

[0041] The saturation magnetization of the soft magnetic metal powder according to this embodiment is preferably 190 Wb·m / kg or more. If the saturation magnetization is 190 Wb·m / kg or more, electronic components with sufficient magnetic properties can be manufactured from this soft magnetic metal powder.

[0042] The reason why the soft magnetic metal powder according to this embodiment exhibits high saturation magnetization has not yet been fully elucidated. However, researchers speculate that the reason is as follows: The soft magnetic metal powder according to this embodiment contains a trace amount of Ni (less than 5 mol%) in addition to Fe and Co. Because the Ni content is less than 5 mol%, the compositional proportions of Fe and Co in the soft magnetic metal powder increase. This is thought to improve the magnetic properties. Furthermore, when obtaining an FeCo alloy by liquid-phase reduction in conventional methods, only fine particles with a low sphericity are obtained. On the other hand, the soft magnetic metal powder according to this embodiment contains a trace amount of Ni (less than 5 mol%), which promotes the reduction reaction of the metal salt. As a result, it is presumed that spherical fine particles can be obtained.

[0043] Next, a method for producing the soft magnetic metal powder according to this embodiment will be described.

[0044] The soft magnetic metal powder according to this embodiment can be produced by a liquid-phase reduction method, in which an aqueous solution of metal salts of Fe, Co, and Ni is reduced with a reducing agent.

[0045] Examples of iron salts include iron (II) sulfate, iron (II) chloride, iron (II) acetate, iron (II) oxalate, iron (III) chloride, and iron (III) sulfate. However, usable iron salts are not limited to these examples. One or more of the exemplified iron salts can be used.

[0046] Examples of cobalt salts include cobalt(II) chloride, cobalt(II) sulfate, and cobalt(II) nitrate. However, usable cobalt salts are not limited to these examples. One or more of the exemplified cobalt salts can be used.

[0047] Examples of nickel salts include nickel(II) chloride, nickel(II) sulfate, nickel(II) nitrate, and nickel(III) fluoride. However, the nickel salts that can be used are not limited to these examples. One or more of the nickel salts listed above can be used.

[0048] The content of the nickel salt in the aqueous metal salt solution is preferably in the range of 0.5 to 4.0 mol %, more preferably 0.8 to 3.8 mol %, and even more preferably 1.0 to 3.5 mol %, relative to 100 mol % in total of the metal salts of Fe, Co, and Ni.

[0049] The aqueous solution of the metal salt may contain one or more complexing agents. The aqueous solution of the metal salt may also contain one or more reducing agents.

[0050] The complexing agent is not particularly limited. Examples of the complexing agent include glycine, alanine, ammonium sulfate, ammonium chloride, and sodium citrate III. However, the complexing agent that can be used is not limited to these examples.

[0051] The amount of the complexing agent added is preferably in the range of 25 to 120 mol % relative to 100% of the total amount of the metal salts.

[0052] The aqueous solution of the metal salt does not necessarily need to contain a reducing agent. However, the aqueous solution of the metal salt may contain a P-based reducing agent. Examples of P-based reducing agents include sodium hypophosphite and calcium hypophosphite. However, the reducing agents that can be used are not limited to these examples.

[0053] The amount of the P-based reducing agent added is preferably in the range of 0.5 to 2.0 mol % relative to 100% of the total amount of the metal salts.

[0054] The acidity of the aqueous solution of the metal salt is adjusted with a pH adjuster, preferably to a pH range of 3.0 to 6.0.

[0055] The pH adjuster is not particularly limited, and examples of the pH adjuster include sodium hydroxide, aqueous ammonia, and sodium bicarbonate.

[0056] The aqueous solution of metal salts may contain metal salts (other metal salts) containing metal elements other than Fe, Co, and Ni. The other metal salts are preferably salts of metals more noble than Ni. Salts of one or more noble metals can be used. Examples of such salts include water-soluble salts of copper, palladium, and platinum. A preferred salt is palladium(II) ammonium chloride. The other metal salts can serve as the starting point for the reduction reaction. Therefore, when the other metal salts are used, it becomes easier to obtain a more uniform soft magnetic metal powder.

[0057] The content of the other metal salts is preferably in the range of 0.1 to 0.5 mol ppm based on the total of the Fe metal salt, the Co metal salt, and the Ni metal salt.

[0058] The aqueous solution of the metal salt may optionally contain a dispersant, a catalyst, or an antifoaming agent.

[0059] The reducing agent used to reduce the aqueous solution of metal salt is not particularly limited. Examples of reducing agents that can be used include B-type reducing agents and hydrazine. One or more reducing agents can be used.

[0060] Examples of B-type reducing agents include sodium borohydride, potassium borohydride, and dimethylaminoborane.

[0061] The amount of the reducing agent added is preferably in the range of 100 to 400 mol % based on the total amount of the metal salts.

[0062] The reducing agent is preferably a reducing solution containing a pH adjuster. The acidity of the reducing solution is preferably adjusted to a pH range of 12 to 14, although this depends on the reducing agent used for reduction.

[0063] The reduction is carried out using a mixture prepared by mixing the reducing solution with an aqueous solution of a metal salt. The preferred reduction temperature is in the range of 60°C to 90°C.

[0064] If the reduction temperature is lower than 60°C, particle growth may be incomplete due to insufficient reaction energy. On the other hand, if the reduction temperature is higher than 90°C, excessive reaction energy may be generated and the reducing agent may be deactivated early. In such cases, the soft magnetic metal powder according to this embodiment may not be obtained.

[0065] A chelating agent may be used as the hydrazine decomposition inhibitor. An example of a chelating agent is anhydrous ethylenediamine (EDA). 1.0 to 5.0 mol % of the chelating agent can be added relative to the total amount of metal salts. The chelating agent can be added by mixing the chelating agent with the reduction solution in advance. Alternatively, the chelating agent can be added after the start of reduction.

[0066] After the reduction reaction, the resulting reaction product can be washed and dried as appropriate to obtain the soft magnetic metal powder according to this embodiment. The soft magnetic metal powder according to this embodiment can also be heat-treated (annealed) to reduce the crystal distortion of the powder particles. The conditions for the heat treatment are not particularly limited. For example, an industrially preferred heat treatment temperature range is 300 to 600 degrees. A preferred heat treatment time is, for example, in the range of 1 to 3 hours.

[0067] The soft magnetic metal powder according to this embodiment may be subjected to a coating treatment. The surface coating treatment method in this embodiment is not particularly limited. Any method can be used as long as it can cover the surface of the soft magnetic metal powder with a compound containing a specific element. Examples of such specific elements include one or more elements selected from aluminum, silicon, chromium, zirconium, titanium, yttrium, and phosphorus. An example of a surface coating treatment method is a method that utilizes the hydrolysis of TEOS. The bond to the surface of the soft magnetic metal powder particles may be a chemical bond or a physical adsorption.

[0068] Examples of this embodiment will be described below, but this embodiment is not limited to these examples.

[0069] Example 1 A solution containing iron (II) sulfate heptahydrate at a concentration of 0.400 mol / L, cobalt (II) sulfate heptahydrate at a concentration of 0.085 mol / L, nickel (II) sulfate hexahydrate at a concentration of 0.015 mol / L, trisodium citrate monohydrate at a concentration of 0.20 mol / L, and ammonium palladium (II) chloride at a concentration of 1.00×10 －７ The compound and pure water were added to a glass beaker so that the concentration was 1000 mol / L. The compound and pure water were then stirred and mixed to obtain an aqueous solution of the metal salt. The pH of the aqueous solution of the metal salt was adjusted to a range of 3.0 to 5.0.

[0070] These compounds were mixed with distilled water so that the concentration of sodium borohydride was 1.00 mol / L and the concentration of sodium hydroxide was 2.70 mol / L, thereby obtaining a reduced solution.

[0071] The reducing solution was added to the aqueous solution of the metal salt while stirring the aqueous solution. Then, the aqueous solution of the metal salt and the reducing solution were mixed. The pH of the resulting mixed solution was adjusted to a range of 11.0 to 13.0.

[0072] After the reduction solution was added, the resulting mixture was heated to 70° C. Thereafter, the mixture was kept at a constant temperature of 70° C. for 2 hours.

[0073] The precipitated powder was then separated from the liquid, washed with water and alcohol, and then dried in an inert atmosphere to obtain a dried powder.

[0074] The dried powder was heat treated in a nitrogen atmosphere at 500° C. for 2 hours, thereby obtaining a crystalline soft magnetic metal powder containing an FeCoNi alloy.

[0075] (Example 2) Soft magnetic metal powder was prepared using the iron salt, cobalt salt, nickel salt, metal salt containing a metal element other than Fe, Co, and Ni (other metal salt), complexing agent, and reducing agent shown in Table 1. Dried powder was obtained by the same production method as in Example 1, except that the reduction temperature was changed as shown in Table 1. Thereafter, the dried powder was not subjected to heat treatment, and the soft magnetic metal powder of Example 2 was obtained. The obtained soft magnetic metal powder was an FeCoNi alloy.

[0076] (Example 3) The soft magnetic metal powder and compound obtained in Example 1 were placed in a glass beaker together with isopropyl alcohol and stirred so that the concentration of the soft magnetic metal powder was 0.30 mol / L, the concentration of tetraethoxysilane (TEOS) was 0.04 mol / L, and the concentration of aqueous ammonia was 0.20 mol / L. The recovered soft magnetic metal powder was then washed and dried in a nitrogen atmosphere. In this way, a soft magnetic metal powder coated with silica was obtained. The compound coating the soft magnetic metal powder particles was silicon dioxide.

[0077] Comparative Example 1 With reference to Example 13 of JP-A No. 2022-138129, a soft magnetic metal powder was obtained as follows.

[0078] The concentration of iron(II) sulfate heptahydrate was 0.40 mol / L, the concentration of cobalt(II) sulfate heptahydrate was 0.05 mol / L, the concentration of nickel(II) sulfate hexahydrate was 0.05 mol / L, the concentration of trisodium citrate monohydrate was 0.18 mol / L, and the concentration of ammonium palladium(II) chloride was 1.00 x 10 －７ The above-mentioned compound was placed in a glass beaker together with 1000 ml of distilled water and mixed so that the concentration became 1 mol / L. To dissolve the compound by mixing, the mixture was stirred using a stirrer at 100 to 300 rpm at a dissolution temperature of 85°C. In this way, an aqueous solution of the metal salt was obtained.

[0079] The above compounds were mixed with 632 ml of distilled water so that the concentration of hydrazine monohydrate was 1.83 mol / L and the concentration of sodium hydroxide aqueous solution was 3.54 mol / L, thus preparing a reducing solution at 25°C.

[0080] Anhydrous ethylenediamine (EDA) was mixed with 18.00 ml of distilled water at room temperature to a concentration of 0.01 mol / L, thus obtaining a hydrazine decomposition inhibitor solution.

[0081] The reducing solution was added over 10 seconds to an aqueous solution of metal salts that was being stirred at 100 to 300 rpm at the previous dissolution temperature, and the pH of the resulting mixture was adjusted to a range of 11.0 to 13.0.

[0082] After the reduction solution was poured into the aqueous solution of metal salts, the resulting mixture was heated to the reduction temperature of 85° C. while being stirred.

[0083] Three minutes after the introduction of the reducing solution began, the hydrazine decomposition inhibitor solution was added dropwise over 10 minutes to the stirred mixture of the aqueous metal salt solution and the reducing solution.

[0084] After the dropwise addition of the hydrazine decomposition inhibitor solution was completed, the temperature of the mixture was kept constant at 85° C., the reduction temperature, for 2 hours while the mixture was stirred.

[0085] After the two hours had elapsed, the stirring was stopped. The precipitated powder was separated from the liquid. The obtained powder was washed with water and alcohol. The powder was then dried in an inert atmosphere. In this way, a crystalline FeCoNi alloy was obtained as a soft magnetic metal powder.

[0086] Comparative Example 2: A solution containing iron (II) sulfate heptahydrate at a concentration of 0.40 mol / L, cobalt (II) sulfate heptahydrate at a concentration of 0.10 mol / L, trisodium citrate monohydrate at a concentration of 0.20 mol / L, and ammonium palladium (II) chloride at a concentration of 2.00 × 10 －７The above compounds were placed in a glass beaker and mixed with distilled water to a concentration of 1000 mol / L. In this way, an aqueous solution of metal salts was obtained. The pH of the aqueous solution of metal salts was adjusted to a range of 3.0 to 5.0.

[0087] The above compounds were mixed with 215 ml of distilled water so that the concentration of sodium borohydride was 1.00 mol / L and the concentration of aqueous sodium hydroxide was 2.70 mol / L, thus preparing a reducing solution.

[0088] The reducing solution was added to the aqueous solution of metal salts to obtain a mixed solution, the pH of which was adjusted to a range of 11.0 to 13.0.

[0089] After the reduction solution was added, the resulting mixture was heated to 70° C. Thereafter, the mixture was kept at a constant temperature of 70° C. for 2 hours.

[0090] The precipitated powder was then separated from the liquid, washed, and dried in an inert atmosphere to obtain a crystalline soft magnetic metal powder containing an FeCo alloy.

[0091] Table 2 shows the particle properties, composition analysis results, and magnetic properties of the soft magnetic metal powders obtained in the examples and comparative examples.

[0092]

[0093]

[0094] Among the particle properties of the soft magnetic metal powder, the average particle size, standard deviation of particle size, and sphericity ratio were determined by the following methods. Using a scanning electron microscope (SEM) (Hitachi High-Tech S-4800 FE-SEM), the soft magnetic metal powder was photographed at a magnification of 20,000 times. The particle properties were evaluated for all particles within the photographed field of view. The average particle size and standard deviation of particle size were calculated by measurement using image analysis software A-zo-kun (Asahi Kasei Engineering Co., Ltd.). The sphericity ratio was calculated from the aforementioned (Equation 1) by measurement using image analysis software A-zo-kun (Asahi Kasei Engineering Co., Ltd.).

[0095] The crystallite diameter of the soft magnetic metal powder was evaluated by Rietveld analysis from measured values ​​obtained using an X-ray diffractometer (D8ADVANCE, manufactured by Bruker Japan Co., Ltd.).

[0096] The composition (Fe, Ni, Co, Si) was evaluated using an X-ray fluorescence analyzer (Rigaku Corporation ZSX Primus II).

[0097] To identify the obtained soft magnetic metal powder and the compounds coating the metal powder particles, the soft magnetic metal powder particles were observed with a field emission transmission electron microscope (FE-TEM) JEM-F200 (JEOL Ltd.) operated in scanning mode. Elemental analysis of the observed particles was performed with an energy dispersive X-ray spectrometer (EDS).

[0098] The composition analysis (O) was evaluated using an oxygen, nitrogen and hydrogen analyzer (Horiba Ltd. EMGA-930).

[0099] The magnetic properties (saturation magnetization (σs)) of the soft magnetic metal powder were evaluated using a vibrating sample magnetometer (VSM) (Tamagawa Seisakusho Co., Ltd., Model TM-VSM2130MRHL).

[0100] The soft magnetic metal powder according to this embodiment has a high sphericity. Therefore, when used in electronic components such as inductors, this soft magnetic metal powder exhibits excellent filling properties and thin film smoothness. Furthermore, the soft magnetic metal powder according to this embodiment has a high saturation magnetization. Therefore, this soft magnetic metal powder can contribute to the miniaturization and high integration of electronic components such as inductors, magnetic cores, and magnetic heads. Furthermore, the soft magnetic metal powder particles are fine particles with a highly uniform particle size. Therefore, this soft magnetic metal powder can be suitably used as a material for constructing small electronic components.

Claims

1. A soft magnetic metal powder containing at least Fe, Co, and less than 5 mol% (excluding 0 mol%) of Ni.

2. The soft magnetic metal powder according to claim 1, having a sphericity of 75% or more, calculated by the following formula (1): (Formula 1) Sphericity = (area / area of ​​smallest circumscribed circle) x 100 3. The soft magnetic metal powder according to claim 1, having a crystallite diameter of greater than 30 nm.

4. The soft magnetic metal powder according to claim 1, having an average particle size of 0.05 μm or more and 1.5 μm or less.

5. The soft magnetic metal powder according to claim 1, having a coefficient of variation calculated by the following formula (2) of 0.25 or less: (Formula 2) Coefficient of variation = Standard deviation of particle diameter / Average particle diameter 6. The soft magnetic metal powder according to claim 1, comprising powder particles coated with a compound containing one or more elements selected from aluminum, silicon, chromium, zirconium, titanium, yttrium, and phosphorus.

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