Preparation method and application of soft magnetic composite material

Abstract

The invention provides a preparation method of a soft magnetic composite material, which comprises the following steps: S1, carrying out jet milling and grading treatment on iron-containing soft magnetic powder to obtain soft magnetic fine powder; s2, dissolving a metal precursor in absolute ethyl alcohol, adding a catalyst, stirring to obtain a precursor solution, adding the soft magnetic fine powder in the S1 into the precursor solution, stirring to obtain an insulating coating solution, filtering, drying, and carrying out heat preservation at high temperature to obtain soft magnetic powder coated with a ceramic insulating layer; s3, performing insulating layer etching on the soft magnetic powder coated with the ceramic insulating layer in the step S2 through a hot atomic layer etching technology to obtain the etched soft magnetic powder coated with the ceramic insulating layer; and S4, mixing the etched soft magnetic powder coated with the ceramic insulating layer with an organic binder, and carrying out compression molding on the mixed powder to obtain the soft magnetic composite material. According to the invention, the effective magnetic conductivity and the total loss performance of the soft magnetic fine powder are obviously improved, the efficiency of the AI chip power supply magnetic element is improved, and the cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of soft magnetic materials, and relates to a method for preparing soft magnetic composite materials and their applications. Background Technology

[0002] As the computing power of AI chips, accelerator cards, and data center servers continues to increase, chip power consumption and current density are rising dramatically. On-chip or packaged power management circuits need to operate at frequencies of 1-20MHz or even higher to achieve rapid dynamic voltage regulation and high power density. To achieve miniaturized inductors, transformers, and other magnetic components with high frequency and high efficiency, more and more solutions are using soft magnetic composite materials or pressed soft magnetic powder cores, and attempting to integrate them near AI chips or even inside the package. Soft magnetic materials, due to their low coercivity, high permeability, and high saturation magnetic induction, are widely used in energy conversion and communication equipment.

[0003] When magnetic materials are exposed to rapidly changing magnetic fields, the total energy of the core decreases due to hysteresis losses and / or eddy current losses. Hysteresis losses are caused by the energy required to overcome the magnetic force retained within the core component. High resistivity helps reduce eddy current losses. However, traditional soft magnetic materials have some limitations in high-frequency applications. For example, although metallic soft magnetic materials have high saturation magnetization and good frequency characteristics, their application is limited by their low resistivity and susceptibility to eddy current losses at high frequencies. While soft magnetic ferrites have high resistivity, their low saturation flux density, poor thermal stability, and high magnetostriction coefficient make them difficult to meet the development requirements of high-power, low-loss, and low-noise power electronic equipment.

[0004] To address these issues, researchers have begun forming insulating coatings on the surfaces of soft magnetic materials to improve resistivity, reduce eddy current losses, and maintain high magnetic properties. However, existing insulating coating techniques still have some limitations. For example, while traditional wet coating methods (such as sol-gel, hydrolytic deposition, and co-precipitation) are simple and low-cost, the ceramic layer thickness is often uneven in fine powder systems with irregular morphologies and narrow gaps, resulting in thin coatings or even weak insulation zones in some particles or localized areas. CN113077953A proposes a method and product for improving the permeability of iron-based magnetic powder cores based on magnetic exchange length. This preparation method involves coating the surface of iron-based soft magnetic powder with a silica insulating layer, adding a binder and ultrasonically dispersing it, and finally mixing the iron-based / silica soft magnetic composite powder, the uniformly dispersed nano-sized iron-based soft magnetic powder, the binder, and the release agent, followed by pressing and heat treatment. This method effectively improves the magnetic induction intensity and permeability of the product. However, this method still faces the challenge of further improving the uniformity and density of the silica insulating layer. Although atomic layer deposition (ALD) can form ceramic films with precise and controllable thickness and extremely uniformity on complex three-dimensional surfaces, its deposition rate is low. The thickness of a single cycle deposition is usually less than 0.2 nm. To obtain a thickness of tens of nanometers, hundreds or even thousands of cycles are required. When processing kilogram-level soft magnetic fine powders, the processing time per batch is long, the equipment occupancy is high, and the energy consumption is large.

[0005] Existing atomic layer etching (ALE) technology mainly serves semiconductor thin film processing, and mostly adopts the form of combining plasma and gas-phase reactants for nanoscale etching of silicon wafers or planar thin films. It does not involve finely adjusting the thickness of wet ceramic coating on the surface of soft magnetic fine powder through thermal atomic layer etching to optimize high-frequency magnetic performance while taking into account production efficiency.

[0006] Therefore, how to form a ceramic insulating layer with uniform thickness and minimal impact on soft magnetic properties through a simple and efficient method while ensuring insulation has become an urgent problem to be solved. Summary of the Invention

[0007] The purpose of this invention is to provide a method for preparing soft magnetic composite materials. By combining a ceramic insulating coating layer formed on the surface of the soft magnetic material with a thermal atomic layer etching process to thin the ceramic insulating coating layer, the invention more effectively solves the problems of uneven film thickness, magnetic degradation caused by thick films, low efficiency, and high cost in the prior art. Furthermore, it significantly improves the effective permeability and total loss performance of the soft magnetic fine powder, improves the efficiency of the power magnetic components of AI chips, and has low cost, thus showing good industrial prospects.

[0008] To achieve the above objectives, the present invention provides a method for preparing a soft magnetic composite material, comprising the following steps: S1. The iron-containing soft magnetic powder is subjected to air jet milling and classification to obtain soft magnetic fine powder with uniform particle size distribution; S2. A sol is coated on the surface of a soft magnetic fine powder using the sol-gel method, and then dried and sintered to form a soft magnetic powder coated with a ceramic insulating layer; S3. The soft magnetic powder coated with the ceramic insulating layer in step S2 is etched by thermal atomic layer etching technology to reduce the thickness of the ceramic insulating layer to 2~15nm, and the etched soft magnetic powder coated with the ceramic insulating layer is obtained. S4. Mix the etched soft magnetic powder coated with a ceramic insulating layer with an organic binder, and press the mixed powder into a mold to obtain a soft magnetic composite material; The sol is one of Al2O3, SiO2, TiO2, ZrO2, MgO, and HfO2.

[0009] The iron-containing soft magnetic powder is at least one of pure iron powder, iron-silicon alloy powder, iron-aluminum alloy powder, iron-silicon-aluminum alloy powder, iron-silicon-chromium alloy powder, and iron-nickel alloy powder.

[0010] In step S1, the average particle size of the iron-containing soft magnetic powder is less than 10 μm, and the particle size range of the soft magnetic fine powder obtained after treatment is 1-8 μm, the D50 particle size is 1-5 μm, the D90 particle size is less than 8 μm, and the oxygen content of the soft magnetic fine powder is 0.1-1.0 wt%.

[0011] Step S2 includes: dissolving the precursor in anhydrous ethanol or isopropanol, adding an appropriate amount of pH adjuster and stirring to hydrolyze the precursor to form a sol, adding the soft magnetic fine powder from S1 to the sol and stirring to obtain soft magnetic fine powder coated with the sol, filtering and drying, and then keeping it at high temperature to obtain soft magnetic powder coated with a ceramic insulating layer. The precursor is a metal alkoxide of aluminum, titanium, zirconium, or hafnium, or tetraethoxysilane, or magnesium nitrate. The metal alkoxide includes one of aluminum isopropanol, tetraisopropyl titanate, tetra-n-propyl zirconate, or tetrabutyl hafnium oxide.

[0012] In step S2, the thickness of the insulating layer is 10 nm - 30 nm.

[0013] Step S3 includes: placing the soft magnetic powder coated with the ceramic insulating layer into the ALD reaction chamber, or into a porous container inside the ALD reaction chamber, for fluidization; replacing the gas in the reaction chamber with an inert gas; alternately loading the first surface treatment gas and the second surface treatment gas into the reaction chamber in a pulsed manner with the inert gas; purging the residual gas with inert gas between the alternations; setting the temperature of the reaction chamber to 150-450℃; and repeating step S3 until the thickness of the ceramic insulating layer is 2-15nm.

[0014] The first and second surface treatment gases include one of NbF5 and triethylamine, TaF5 and ammonia, and TiF4 and ammonia.

[0015] The organic binder is one or more of phenolic resin, epoxy resin, silicone resin, polyfluorinated ethylene, and melamine resin, and the mass percentage of the organic binder is 0.5% to 2.5%.

[0016] A composite soft magnetic powder is obtained by steps S1 to S3 of the preparation method described above.

[0017] The method for preparing the soft magnetic composite material is applied to the preparation of magnetic components inside the power supply of AI chips.

[0018] Beneficial effects: (1) The present invention adopts a combination process of wet coating to form the initial ceramic insulating layer and thermal atomic layer etching to thin the ceramic insulating layer. Under the premise of ensuring insulation, the thickness of the ceramic layer is significantly reduced, and the magnetic properties of the soft magnetic fine powder are improved. Compared with the traditional single wet coating or atomic layer deposition process, the combination process of the present invention can more effectively solve the problems of uneven film thickness, magnetic degradation caused by thick film, low efficiency and high cost in the prior art.

[0019] (2) The present invention forms an initial thick ceramic insulating layer by wet coating. By utilizing the high coverage and high throughput characteristics of the wet process on the surface of soft magnetic fine powder, it ensures that each particle and its small depressions are covered by the ceramic layer, which effectively improves the uniformity and thickness distribution of the coating and overcomes the problem of thin coating or weak insulation in some areas in the traditional wet coating.

[0020] (3) This invention uses thermal atomic layer etching (ALD) to thin the initial ceramic insulating layer at the nanoscale under plasma-free conditions, avoiding the problems of low efficiency and high cost caused by relying entirely on ALD to form a thin film. By reasonably selecting the types of reactants and the process window, it is ensured that the crystal structure and magnetic properties of the soft magnetic substrate are not significantly damaged, and the change in saturation magnetic induction intensity before and after treatment does not exceed 5%, and the change in coercivity does not exceed 10%.

[0021] (4) By using the self-limiting etching characteristics of thermal atomic layer etching, the present invention can accurately reduce the initial thick film to below 10nm, preferably 2-15nm, which significantly improves the effective permeability and total loss performance of soft magnetic fine powder under 1MHz and 0.05T conditions, and improves the efficiency of AI chip power magnetic components.

[0022] (5) The combined process method of the present invention is simple and controllable, applicable to a variety of soft magnetic fine powders and ceramic systems, and is particularly suitable for the AI ​​chip industry’s demand for mass production and low-cost supply of materials, and has good prospects for industrial application. Detailed Implementation

[0023] The present invention will now be described in detail with reference to specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments. Unless otherwise specified, the equipment used in the following embodiments is conventional equipment in the art; unless otherwise specified, the reagents used are commercially available products or prepared using conventional methods in the art. Specific details not described in the following embodiments can be achieved using conventional experimental methods in the art.

[0024] Terminology Explanation Coercivity is the strength of the reverse magnetic field required to reduce the magnetization (or magnetic induction) of a material to zero, reflecting the material's ability to "retain magnetism." The lower the coercivity, the easier the material is to magnetize and demagnetize, the narrower the hysteresis loop, and the smaller the hysteresis loss. Materials with low coercivity (typically less than 100 A / m) are suitable for high-frequency alternating magnetic field applications, such as inductors in switching power supplies and AI chip power supplies.

[0025] Permeability represents how easily a material can be magnetized under the influence of an external magnetic field. The higher the permeability, the stronger the magnetic flux density can be generated under the same magnetic field, which is beneficial for increasing the inductance value and reducing the size of the device.

[0026] Saturation magnetic flux density represents the maximum magnetic flux density that a material can withstand. The greater the saturation magnetic flux density, the more power an inductor or transformer can handle in the same volume, thus avoiding performance degradation caused by core saturation.

[0027] Total loss, which consists of hysteresis, eddy current and residual loss, usually increases significantly with increasing frequency at a fixed magnetic flux density and is the core indicator for evaluating the high-frequency performance of magnetic materials.

[0028] A method for preparing a soft magnetic composite material includes the following steps: S1. The iron-containing soft magnetic powder is subjected to air jet milling and classification to obtain soft magnetic fine powder with uniform particle size distribution; S2. A sol is coated on the surface of a soft magnetic fine powder using the sol-gel method, and then dried and sintered to form a soft magnetic powder coated with a ceramic insulating layer; S3. The ceramic insulating layer of the soft magnetic powder coated with the ceramic insulating layer in step S2 is etched by thermal atomic layer etching technology to reduce the thickness of the ceramic insulating layer to 2-15nm, and the etched soft magnetic powder coated with the ceramic insulating layer is obtained. S4. Mix the etched soft magnetic powder coated with a ceramic insulating layer with an organic binder, and press the mixed powder into a mold to obtain a soft magnetic composite material; The sol is one of Al2O3, SiO2, TiO2, ZrO2, MgO, and HfO2. The thickness of the insulating layer in step S2 is 10 nm - 100 nm.

[0029] In step S1, the average particle size of the iron-containing soft magnetic powder is less than 10 μm, and the resulting soft magnetic fine powder has a particle size range of 1-8 μm, a D50 particle size of 1-5 μm, a D90 particle size of less than 8 μm, and an oxygen content of 0.1-1.0 wt%. The iron-containing soft magnetic powder is at least one of pure iron powder, iron-silicon alloy powder, iron-aluminum alloy powder, iron-silicon-aluminum alloy powder, iron-silicon-chromium alloy powder, and iron-nickel alloy powder.

[0030] Step S2 includes: dissolving the precursor in anhydrous ethanol or isopropanol, adding an appropriate amount of pH adjuster or pH adjuster and chelating agent, stirring to hydrolyze the precursor to form a sol, adding the soft magnetic fine powder from S1 to the sol and stirring to obtain soft magnetic fine powder coated with the sol, filtering and drying, and then keeping it at high temperature to obtain soft magnetic powder coated with a ceramic insulating layer; wherein, the precursor and pH adjuster are shown in Table 1.

[0031] Table 1 Step S3 includes: placing the soft magnetic powder coated with ceramic insulating layer into the ALD reaction chamber, or into a porous container inside the ALD reaction chamber, for fluidization; replacing the gas in the reaction chamber with inert gas; alternately loading the first surface treatment gas and the second surface treatment gas from Table 2 into the reaction chamber in a pulsed manner with inert gas; purging the residual gas with inert gas between alternations; setting the temperature of the reaction chamber to 150-450℃; and repeating step S3 until the thickness of the ceramic insulating layer is 2-15nm.

[0032] Table 2 Example 1 This embodiment provides a method for preparing a soft magnetic composite material, including the following steps: (1) Select FeSiAl soft magnetic fine powder with an average particle size of 3μm and control the oxygen content of the powder to be below 0.3wt%. The fine powder is obtained by air jet milling and classification process. The D50 particle size is less than 3μm and the D90 particle size is less than 5μm. The above air jet milling and classification process is disclosed in the prior art CN104174857B.

[0033] (2) Wet coating to form the initial alumina layer: Aluminum isopropoxide is dissolved in anhydrous ethanol. The mass ratio of aluminum isopropoxide, anhydrous ethanol and FeSiAl soft magnetic fine powder is controlled to be 1:100:100. The FeSiAl soft magnetic fine powder from step (1) is added to the sol and stirred at room temperature for 45 min to make the sol uniformly coat the powder surface. It is filtered and dried at 100℃ for 2 h, and then kept at 500℃ for 1 h to convert the precursor into an alumina layer. The thickness of the initial alumina insulating layer is observed by TEM sectioning. The average thickness of the initial alumina layer is about 15-27 nm, and the thickness on different particles is distributed between 10-30 nm. Two FeSiAl soft magnetic fine powders coated with the initial alumina layer are prepared according to the above steps, one of which is used as a comparative example.

[0034] (3) Load the FeSiAl soft magnetic fine powder coated with the initial alumina layer into the ALD reaction chamber, or place it into a porous container inside the ALD reaction chamber for fluidization. Then, repeatedly evacuate and replace with nitrogen at least three times. Set the temperature of the reaction chamber to 200~460℃ and perform the following cycle operation under nitrogen protection: ① Introduce halogen-containing first surface treatment gas NbF5 to cause it to undergo a self-limiting reaction with the surface of the alumina layer to form a fluorinated modified layer; ②Use nitrogen gas to purge excess first surface treatment gases and volatile byproducts; ③ Introduce the second surface treatment gas triethylamine, which undergoes ligand exchange or reduction reaction with the fluorinated modified layer to generate volatile byproducts and remove the fluorinated modified layer; ④ Purge the second surface treatment gases and volatile byproducts with nitrogen gas.

[0035] Steps ①-④ constitute an atomic layer etching cycle. Through etching experiments on a flat standard sample, the average etching depth per cycle was determined to be approximately 0.15 nm / cycle.

[0036] Based on the initial alumina layer thickness and the target thickness requirement, the etching cycle was set to 50 times. After etching, the average thickness of the final alumina insulating layer was measured to be approximately 6 nm, with a thickness distribution between 4 and 15 nm.

[0037] Triethylamine is an organic base that can undergo an effective ligand exchange reaction with the fluorinated modified layer (such as the Nb-OF layer) formed in the first step, generating volatile fluorinated amine products (such as NbF5·N(Et)3), thereby removing the etched material in the gas phase. Using NbF5 and triethylamine to etch the alumina layer ensures that the crystal structure and magnetic properties of the soft magnetic substrate are not significantly damaged by chlorides because it is chloride-free.

[0038] Wet coating forms the initial alumina layer at low cost and high yield, while the atomic layer etching rate is much higher than the atomic layer deposition rate. This embodiment combines the high throughput and low cost of wet coating with the atomic precision thinning capability of ALE, seeking a more feasible and cost-effective solution on an industrial scale while ensuring insulation, uniformity and magnetic properties.

[0039] (4) High-frequency magnetic property comparison test The soft magnetic fine powder for comparison and the soft magnetic fine powder after atomic layer etching were respectively mixed with an organic binder at a mass ratio of 97:3 and pressed into ring-shaped samples suitable for packaging-level inductance simulation. These were respectively designated as the comparative sample and the sample of the present invention. The organic binder was one or more of phenolic resin, epoxy resin, silicone resin, polyfluorinated ethylene, and melamine resin.

[0040] Effective permeability and loss were tested at 1 MHz and a magnetic flux density of 0.05 T. The results showed that the effective permeability of the sample of the present invention was about 70, while that of the comparative sample was about 60, representing an increase of about 17%. The total loss of the sample of the present invention was about 1.5 W / kg, while that of the comparative sample was about 2.0 W / kg, representing a decrease of about 30%. FeSiAl soft magnetic powder was coated with 10 nm Al2O3 using the ALD method, and then mixed with an organic binder at a mass ratio of 97:3 and pressed into a toroidal sample suitable for simulating packaged inductors. The effective permeability tested at 1 MHz and a magnetic flux density of 0.05 T was 85–110, and the loss was 1.8–2.5 W / kg.

[0041] Ptotal = Ph + Pe + Pex + Pr Hysteresis loss (Ph): proportional to the square of the magnetic flux density amplitude B, and proportional to the frequency f (fB). 2 This is caused by magnetic domain flipping.

[0042] Eddy current loss (Pe): with f 2 B 2 It is directly proportional to the resistivity of the material and the degree of insulation between particles.

[0043] Residual / abnormal losses (Pex and Pr): caused by the hysteresis of the dynamic response of the domain walls at high frequencies, and are related to the 3 / 2 power of frequency and magnetic flux density.

[0044] Due to the extremely low magnetic flux density of 0.05T and extremely high frequency of 1MHz, the soft magnetic composite material of this invention exhibits eddy currents suppressed by both the alumina layer and insulating bonding in the "skin limit-core resonance region." The remaining loss is dominated by hysteresis and residual eddy currents, and the hysteresis term is sharply reduced after B is halved. The soft magnetic composite material prepared using the method of this embodiment, because the oxide undergoes high-temperature sintering during the wet coating process to form a dense crystalline oxide, and after ALE removal of the surface layer, the remaining oxide remains a dense crystalline oxide, exhibiting higher resistivity and lower dielectric loss than amorphous oxides formed by direct low-temperature oxidation using ALD.

[0045] Example 2: This embodiment provides a method for preparing a soft magnetic composite material, including the following steps: (1) Soft magnetic fine powder: FeSiCr soft magnetic fine powder with an average particle size of 2μm was selected, and the oxygen content of the powder was controlled at 0.5wt%. The fine powder was obtained by air jet milling and classification process, with a D50 particle size of 2μm and a D90 particle size of less than 4μm.

[0046] (2) Wet coating to form the initial silicon oxide layer: Tetraethoxysilane was dissolved in anhydrous ethanol, and appropriate amounts of water and 25-28 wt% concentrated ammonia were added. The amount of concentrated ammonia added was 1%-5% of the total volume of the TEOS ethanol solution. The concentration of Si(OC2H5)4 was controlled at 0.35 mol / L, and the mixture was stirred to form a silicon-containing sol. FeSiCr soft magnetic fine powder was added to the sol and stirred at room temperature for 3 h to make the sol uniformly coat the powder surface. The powder was filtered and dried at 90℃ for 3 h, and then kept at 600℃ for 1.5 h to convert the precursor into a silicon oxide layer, thus obtaining the initial silicon oxide insulating layer. Through cross-sectional observation and thickness estimation, the average thickness of the initial silicon oxide layer was about 17-27 nm, and the thickness distribution on different particles was between 15-30 nm. Two FeSiAl soft magnetic fine powders coated with the initial silicon oxide layer were prepared according to the above steps, one of which was used as a comparative example.

[0047] (3) Thermal atomic layer etching to thin the silicon oxide layer The FeSiAl soft magnetic fine powder coated with the initial silicon oxide layer is loaded into the ALD reaction chamber, or placed in a porous container inside the ALD reaction chamber, and fluidized. Then, the chamber is repeatedly evacuated and replaced with nitrogen at least three times. The temperature of the reaction chamber is set to 350°C, and the following cycle is performed under argon protection: ① Introduce the first surface treatment gas TaF5 containing halogens, so that it undergoes a self-limiting reaction with the surface of the silicon oxide layer to form a fluorinated modified layer; ②Use nitrogen gas to purge excess first surface treatment gases and volatile byproducts; ③ Introduce ammonia, a second surface treatment gas, to react with the fluorinated modified layer via ligand exchange, generating volatile byproducts and removing the fluorinated modified layer; ④ Purge the second surface treatment gases and volatile byproducts with nitrogen gas.

[0048] Steps ①-④ constitute a thermal atomic layer etching cycle. Through etching experiments on a flat standard sample, the average etching depth per cycle was determined to be approximately 0.2 nm / cycle.

[0049] Based on the initial silicon oxide layer thickness and the target thickness requirement, the etching cycle was set to 60 times. After etching, the average thickness of the final silicon oxide insulating layer was measured to be approximately 5 nm, with a thickness distribution between 3 and 17 nm.

[0050] (4) High-frequency magnetic property comparison test Two portions of soft magnetic fine powder were mixed with an organic binder at a mass ratio of 98:2 and pressed into a ring-shaped composite material suitable for packaging-level inductance simulation.

[0051] Effective permeability and loss were tested at 2 MHz and a magnetic flux density of 0.08 T. Compared with a sample prepared by a control powder using only wet coating without thermal atomic layer etching, the results showed that the effective permeability of the sample of the present invention was about 75, while that of the control sample was about 65, representing an increase of about 15% in effective permeability. The total loss of the sample of the present invention was about 1.8 W / kg, while that of the control sample was about 2.2 W / kg, representing a decrease of about 20% in total loss.

[0052] It should be understood that the above description of the preferred embodiments is quite detailed, but it should not be considered as a limitation on the scope of protection of this invention. Those skilled in the art, under the guidance of this invention, can make substitutions or modifications without departing from the scope of protection of the claims of this invention, and all such substitutions or modifications fall within the scope of protection of this invention. The scope of protection of this invention should be determined by the appended claims.

Claims

1. A method of producing a soft magnetic composite material, characterized by, The method comprises the following steps: S1. Airflow milling and grading treatment of the iron-containing soft magnetic powder to obtain soft magnetic fine powder with uniform particle size distribution; S2. Coating sol on the surface of the soft magnetic fine powder by sol-gel method, and then drying and sintering to obtain soft magnetic powder coated with ceramic insulating layer; S3. Etching the ceramic insulating layer of the soft magnetic powder coated with ceramic insulating layer in step S2 by thermal atomic layer etching technology, reducing the thickness of the ceramic insulating layer to 2-8 nm, and obtaining soft magnetic powder body coated with etched ceramic insulating layer; S4. Mixing the soft magnetic powder body coated with etched ceramic insulating layer with an organic binder, and pressing the mixed powder to obtain a soft magnetic composite material; The sol is one of Al2O3, SiO2, TiO2, ZrO2, MgO, and HfO2.

2. The method of claim 1, wherein the soft magnetic composite material is prepared by the steps of: The iron-containing soft magnetic powder is at least one of pure iron powder, iron-silicon alloy powder, iron-aluminum alloy powder, iron-silicon-aluminum alloy powder, iron-silicon-chromium alloy powder, and iron-nickel alloy powder. ​ 3. The method of claim 1, wherein the soft magnetic composite material is prepared by the steps of: mixing the magnetic powder and the resin to form a mixture; and heating the mixture to a temperature of 150 to 300°C for 1 to 10 hours. The average particle size of the iron-containing soft magnetic powder in step S1 is less than 10 μm, and the particle size of the obtained soft magnetic fine powder after treatment is in the range of 1-8 μm, the D50 particle size is 1-5 μm, the D90 particle size is less than 8 μm, and the oxygen content of the soft magnetic fine powder is 0.1-1.0 wt%.

4. The method of claim 1, wherein the soft magnetic composite material is prepared by the steps of: Step S2 comprises: dissolving a precursor in anhydrous ethanol or isopropanol, adding an appropriate amount of pH adjuster and stirring to hydrolyze the precursor to form a sol, adding the soft magnetic fine powder in step S1 to the sol and stirring to obtain soft magnetic fine powder coated with sol, filtering, drying, and then obtaining soft magnetic powder coated with ceramic insulating layer after high-temperature heat preservation; ​ The precursor is a metal alkoxide of aluminum, titanium, zirconium, or hafnium, or tetraethoxysilane or magnesium nitrate, and the metal alkoxide includes one of aluminum isopropanol, titanium acid tetraisopropyl ester, zirconium acid tetra-n-propyl ester, and hafnium acid tetrabutyl ester.

5. The method of claim 1, wherein the soft magnetic composite is prepared by the steps of: The thickness of the ceramic insulating layer in step S2 is 10 nm-30 nm.

6. The method of claim 1, wherein the soft magnetic composite material is prepared by the steps of: mixing the magnetic powder and the resin to form a mixture; and heating the mixture to a temperature of 150°C to 300°C for 1 to 10 hours. Step S3 comprises: placing the soft magnetic powder coated with ceramic insulating layer in an ALD reaction chamber or a porous container in the ALD reaction chamber, fluidizing, replacing the gas in the reaction chamber with an inert gas, and alternately loading the first surface treatment gas and the second surface treatment gas into the reaction chamber in a pulse manner with the inert gas, purging the residual gas between the alternations, setting the temperature of the reaction chamber to 150-450℃, and repeating step S3 until the thickness of the ceramic insulating layer is 2-15 nm.

7. The method of claim 6, wherein the soft magnetic composite material is prepared by the steps of: mixing the magnetic powder and the resin to form a mixture; and heating the mixture to a temperature of 150°C to 300°C for 1 to 10 hours. The first surface treatment gas and the second surface treatment gas include one of NbF5 and triethylamine, TaF5 and ammonia, and TiF4 and ammonia.

8. The method of claim 1, wherein the soft magnetic composite material is prepared by the steps of: mixing the magnetic powder and the resin to form a mixture; and heating the mixture to a temperature of 150°C to 300°C for 1 to 10 hours. The organic binder is one or more of phenolic resin, epoxy resin, silicone resin, polyfluorinated ethylene, and melamine resin, and the mass fraction of the organic binder is 0.5-2.5%.

9. A composite soft magnetic powder, characterized by, The steps S1-S3 are obtained by the preparation method of any one of claims 1-8.

10. Application of the preparation method of the soft magnetic composite material of any one of claims 1-8 in the preparation of internal magnetic elements of AI chip power supplies.

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