Soft magnetic composite material for high-frequency inductors and method for producing the same

Abstract

The application provides a soft magnetic composite material for high-frequency inductance and a preparation method thereof, and belongs to the technical field of soft magnetic materials. The soft magnetic composite material for high-frequency inductance is composed of mixed magnetic powder, a ZnO insulation layer and a binder. The mixed magnetic powder is composed of 30 wt.%-70 wt.% Fe-based nanocrystalline soft magnetic powder and the balance of FeNi soft magnetic powder. The ZnO insulation layer is coated on the surface of the mixed magnetic powder by a chemical co-precipitation method. The binder is selected from one or more of epoxy resin, silicone resin and phenolic resin. Through the synergistic design of the ZnO insulation layer and the Fe-based nanocrystalline / FeNi bimodal particle size distribution structure, the synergistic optimization of high-frequency loss performance, thermal stability and high-pressure crushing strength is realized, and the technical problems of high-frequency eddy current loss, poor thermal stability and large process energy consumption in the prior art are solved.

Description

Technical Field

[0001] This invention relates to the field of soft magnetic materials technology, specifically to a soft magnetic composite material for high-frequency inductors and its preparation method. Background Technology

[0002] With the rapid development of 5G communication technology and third-generation semiconductors, the operating frequency and power density of electronic products are constantly increasing, and the integration of internal electronic components is also increasing. This places stringent requirements on inductors, such as high frequency, low loss, miniaturization, and high reliability. Soft magnetic composites (SMCs), as the core material of inductors, directly determine the efficiency and power density of inductors.

[0003] The loss of soft magnetic composite materials under high-frequency conditions is mainly eddy current loss, including eddy current loss inside the magnetic powder particles and eddy current loss between magnetic powder particles. At present, research on soft magnetic composite materials mainly focuses on powder coating, particle size distribution and molding process. There are three main types of powders used in existing high-frequency magnetic powder cores: (1) carbonyl iron powder core, which has low cost but high high-frequency loss and low saturation magnetization; (2) FeNi alloy powder core, which has high permeability but high cost; (3) Fe-based nanocrystalline powder core, which has excellent comprehensive performance but poor compressibility. In recent years, Fe-based nanocrystalline / FeNi composite magnetic powder cores have received widespread attention because they combine high permeability, high saturation magnetic induction and moderate cost.

[0004] However, existing Fe-based nanocrystalline / FeNi composite magnetic powder core technology has the following technical bottlenecks: First, the insulation coating system is unreasonable. Existing technologies mainly use organic or chemical conversion films such as organosilicon resins, silane coupling agents, or phosphates as the insulation layer, as shown in patent document CN117936217A. These organic insulation layers are prone to decomposition and carbonization at high temperatures (>300℃), leading to insulation failure; moreover, the low thermal conductivity of organic layers is not conducive to heat dissipation under high-frequency operating conditions, limiting the application of materials in high-frequency, high-power scenarios.

[0005] Second, the manufacturing process is energy-intensive. Existing technologies generally employ a two-stage process of hot pressing (150-220 ℃) ​​+ high-temperature annealing (400-550 ℃) (e.g., patent document CN117936217A). Although high-temperature annealing can release internal stress and improve soft magnetic properties, it has low energy efficiency, high equipment requirements, and long production cycles, making it difficult to meet the needs of green manufacturing and cost control.

[0006] Third, achieving a balance in performance is difficult. Existing technologies often sacrifice high-frequency loss performance in pursuit of high permeability, or result in insufficient crush strength when reducing losses, making it difficult to simultaneously meet the dual requirements of high-frequency inductors for soft magnetic properties and mechanical properties.

[0007] Therefore, there is an urgent need to develop a new insulation coating system and simplify the preparation process to achieve a synergistic improvement in high-frequency low-loss performance, thermal stability, high-voltage crush strength and low-energy manufacturing while ensuring excellent soft magnetic properties. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides a soft magnetic composite material for high-frequency inductors and its preparation method. The soft magnetic composite material for high-frequency inductors has the advantages of high-frequency low-loss performance, thermal stability, and high-voltage crushing strength. The preparation method has the advantage of low process energy consumption.

[0009] The specific technical solution of this invention is as follows: In a first aspect, the present invention provides a soft magnetic composite material for high-frequency inductors, comprising a mixed magnetic powder, a ZnO insulating layer, and a binder; wherein the mixed magnetic powder comprises 30 wt.% to 70 wt.% Fe-based nanocrystalline soft magnetic powder and the balance FeNi soft magnetic powder, wherein the median particle size of the Fe-based nanocrystalline soft magnetic powder and the FeNi soft magnetic powder is... D 50 The ZnO insulating layer is coated onto the surface of the mixed magnetic powder by chemical co-precipitation, with a ratio of 3:1 to 10:1. The mass of the ZnO precursor used to deposit the ZnO insulating layer is 1.5 wt.% to 2.0 wt.% of the mass of the mixed magnetic powder. The binder is selected from one or more of epoxy resin, silicone resin and phenolic resin, and the mass of the binder is 2.5 wt.% to 3.5 wt.% of the total mass of the mixed magnetic powder.

[0010] Secondly, the present invention provides a method for preparing the above-mentioned soft magnetic composite material for high-frequency inductors, comprising the following steps: S1. Preparation of mixed magnetic powder: Fe-based nanocrystalline soft magnetic powder and FeNi soft magnetic powder are mixed at a mass ratio of 30:70 to 70:30, so that the FeNi soft magnetic powder fills the gaps between the Fe-based nanocrystalline soft magnetic powder to obtain mixed magnetic powder; S2. Surface activation treatment: The mixed magnetic powder and silane coupling agent described in step S1 are ultrasonically dispersed in an organic solvent to obtain activated mixed magnetic powder; S3, Insulating Layer Coating: The zinc salt precursor is dissolved in anhydrous ethanol, and the activated mixed magnetic powder described in step S2 is added. The mass of the zinc salt precursor is 1.5 wt.%~2.0 wt.% of the total mass of the mixed magnetic powder. The pH is adjusted to 8~11, and the reaction is stirred under a water bath at 55~65 ℃ to generate nano-ZnO in situ and uniformly coat the surface of the mixed magnetic powder. After drying, ZnO-coated mixed magnetic powder is obtained. S4. Adhesive Composite: Dissolve the adhesive in an organic solvent, add the ZnO-coated mixed magnetic powder obtained in step S3, ultrasonically disperse and continuously stir until the organic solvent is completely evaporated, and then vacuum dry to obtain the composite powder. S5. Molding and curing: The composite powder described in step S4 is cold-pressed at room temperature under a pressure of 500~700 MPa to obtain a molded blank; the molded blank is cured at 180~220 ℃ to obtain a soft magnetic composite material.

[0011] The positive and progressive effects of this invention are as follows: This invention provides a soft magnetic composite material for high-frequency inductors and its preparation method. First, through the synergistic design of a ZnO insulating layer and a Fe-based nanocrystal / FeNi bimodal particle size distribution structure, a significant reduction in high-frequency losses is achieved. The high resistivity of the ZnO insulating layer effectively blocks the eddy current path between particles, and its high thermal conductivity rapidly disperses the heat generated by high-frequency losses, avoiding performance degradation caused by heat accumulation. The introduction of small-diameter FeNi powder significantly reduces eddy current losses within the particles, and the close packing of the bimodal structure reduces the air gap demagnetization field and hysteresis losses. Second, through the mechanical interlocking effect of the bimodal particle size distribution and the interfacial strengthening effect of the ZnO insulating layer, a synergistic effect of high-pressure crushing strength and low-temperature processing is achieved. Small-diameter FeNi powder fills the gaps between large-diameter nanocrystals to form a close-packed structure. The nanocrystals act as a rigid framework, and FeNi acts as a plastic filler, forming a composite structure that combines rigidity and flexibility. The chemical bonding between ZnO and the Fe-based nanocrystal surface, as well as the mechanical interlocking with the FeNi surface, significantly improves the interfacial bonding strength. Finally, through compositional design and structural innovation, a low-temperature cold pressing-curing process is achieved to replace the high-temperature hot pressing-annealing process. The lubricating effect of the ZnO insulating layer reduces the pressing pressure requirement, the densification effect of the bimodal structure reduces molding energy consumption, and the low-temperature curing temperature avoids grain growth and insulation degradation caused by high-temperature annealing. Equipment investment and operating costs are significantly reduced, and there is no need for high-temperature sintering furnaces and inert atmosphere protection, which has significant advantages in green manufacturing and industrialization value. Attached Figure Description

[0012] Figure 1 This is a SEM image of the soft magnetic composite material in Example 1.

[0013] Figure 2 The graphs show the permeability of the soft magnetic composite materials in Examples 1-3 and Comparative Examples 1-2 as a function of frequency.

[0014] Figure 3 The graphs show the loss of the soft magnetic composite materials in Examples 1-3 and Comparative Examples 1-2 as a function of frequency.

[0015] Figure 4 The VSM curves are for the soft magnetic composite materials in Examples 1-3 and Comparative Examples 1-2.

[0016] Figure 5 The image shows a comparison of the crush strength of the soft magnetic composite materials in Examples 1-3 and Comparative Examples 1-2. Detailed Implementation

[0017] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below. It should be noted that the following embodiments are only used to illustrate the implementation methods and typical parameters of the present invention, and are not intended to limit the parameter range described in the present invention. Reasonable variations derived therefrom are still within the protection scope of the present invention.

[0018] It should be noted that the endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0019] Unless otherwise defined, all terms, symbols, and other scientific terms used herein are intended to have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In some instances, terms having a conventional meaning are defined herein for clarification or ease of reference, and such definitions should not be construed as indicating a significant difference from conventional understanding in the art. The technical methods described or referenced herein are generally well understood by those skilled in the art and employed by conventional methods. Unless otherwise stated, the use of commercially available kits, reagents, and instruments shall be performed according to the manufacturer's instructions and parameters.

[0020] The specific technical solution of this invention is as follows: In a first aspect, the present invention provides a soft magnetic composite material for high-frequency inductors, comprising a mixed magnetic powder, a ZnO insulating layer, and a binder; wherein the mixed magnetic powder comprises 30 wt.% to 70 wt.% Fe-based nanocrystalline soft magnetic powder and the balance FeNi soft magnetic powder, wherein the median particle size of the Fe-based nanocrystalline soft magnetic powder and the FeNi soft magnetic powder is... D 50 The ZnO insulating layer is coated onto the surface of the mixed magnetic powder by chemical co-precipitation, with a ratio of 3:1 to 10:1. The mass of the ZnO precursor used to deposit the ZnO insulating layer is 1.5 wt.% to 2.0 wt.% of the mass of the mixed magnetic powder. The binder is selected from one or more of epoxy resin, silicone resin and phenolic resin, and the mass of the binder is 2.5 wt.% to 3.5 wt.% of the total mass of the mixed magnetic powder.

[0021] The high-frequency inductor soft magnetic composite material provided by this invention achieves a balance between high-frequency low-loss stability and high-voltage collapse strength through the synergistic design of a nano-ZnO inorganic insulating layer and an Fe-based nanocrystalline / FeNi bimodal particle size distribution structure. The mixed magnetic powder consists of 30 wt.%~70 wt.% Fe-based nanocrystalline soft magnetic powder and the balance FeNi soft magnetic powder, with a particle size ratio of 3:1~10:1. This allows the small-diameter FeNi powder to fill the gaps between the large-diameter nanocrystalline powder, forming a close-packed structure. This structure reduces high-frequency losses through a triple mechanism: first, the introduction of small FeNi particles significantly reduces eddy current losses within the particles; second, shortening the interparticle distance reduces the air gap demagnetizing field and lowers hysteresis losses; and third, the ZnO insulating layer blocks the eddy current path between particles, and its high thermal conductivity effectively suppresses the accumulation of high-frequency heat loss. The high resistivity of the ZnO insulating layer and the high resistivity of the FeNi powder form a gradient insulation structure, while the high thermal conductivity of ZnO synergistically complements the low eddy current loss characteristics of the nanocrystals, enabling the composite material to maintain stable magnetic properties in the high-frequency range.

[0022] The ZnO insulating layer is coated onto the surface of the mixed magnetic powder using a chemical co-precipitation method, with the ZnO precursor accounting for 1.5 wt.%~2.0 wt.% of the mixed magnetic powder mass. This coating layer forms Fe-O-Zn chemical bonds with the Fe-based nanocrystal surface and mechanical bonds with the FeNi surface, significantly improving the interfacial bonding strength. Simultaneously, the high hardness and excellent thermal stability of ZnO maintain the nanostructure under low-temperature curing conditions, avoiding the degradation of insulation performance caused by high-temperature processing. The binder forms a three-dimensional cross-linked network during low-temperature vacuum curing, synergistically providing mechanical support with the ZnO layer. The Fe-based nanocrystal powder acts as a rigid framework dispersed in the FeNi plastic matrix, forming a composite structure that combines rigidity and flexibility, resulting in a significantly superior crushing strength compared to single-material systems. Furthermore, the ZnO insulating layer, Fe-based nanocrystal soft magnetic powder, and FeNi soft magnetic powder achieve synergistic optimization under specific ratios and particle size combinations, enabling the soft magnetic composite material for high-frequency inductors to possess both excellent soft magnetic properties and mechanical properties.

[0023] In one possible implementation, the median particle size of the Fe-based nanocrystalline soft magnetic powder D 50 The median particle size of the FeNi soft magnetic powder is 20~35 μm. D 50 The particle size is 2~12 μm. By limiting the specific particle size range (20~35 μm for Fe-based nanocrystalline soft magnetic powder and 2~12 μm for FeNi soft magnetic powder), it is ensured that small FeNi particles effectively fill the gaps between large nanocrystalline particles, forming a compact packing structure, increasing the packing density and reducing the porosity, and simultaneously optimizing the magnetic and mechanical properties.

[0024] In one possible implementation, the Fe-based nanocrystalline soft magnetic powder in the mixed magnetic powder has a mass percentage content of 30 wt.% to 40 wt.%. Limiting the preferred proportion range of 30 wt.% to 40 wt.% allows the soft magnetic composite material for high-frequency inductors to have FeNi as the main phase, resulting in higher permeability and lower high-frequency loss, making it suitable for high-frequency, high-efficiency inductor applications.

[0025] In one possible implementation, the Fe-based nanocrystalline soft magnetic powder is a Fe-Si-B-Cu-Nb nanocrystalline soft magnetic powder. The Fe-Si-B-Cu-Nb nanocrystalline soft magnetic powder system possesses high saturation magnetic induction, low coercivity, and excellent high-frequency characteristics, providing high Bs support and intrinsically low loss characteristics for soft magnetic composite materials used in high-frequency inductors.

[0026] Furthermore, the composition of the Fe-based nanocrystalline soft magnetic powder includes: Fe 59.7 at.%~70.8 at.%, Si 13.5 at.%~15.5 at.%, B 9.0 at.%~12.0 at.%, Cu 0.7 at.%~0.9 at.%, Nb 3 at.%~4.0 at.%, and selectively added Co 10 at.%~11 at.%, P 2 at.%~3 at.%, C 2 at.%~3 at.%, or Ni 4 at.%~5 at.%. Limiting the above composition helps to reduce the thermal expansion coefficient of the Fe-based nanocrystalline soft magnetic powder to match the ZnO insulating layer, improve the interfacial bonding strength, while maintaining high amorphous forming ability and excellent soft magnetic properties.

[0027] Furthermore, the atomic percentage composition formula of the Fe-based nanocrystalline soft magnetic powder is: Fe 69.7 Si 15.5 B 10 Nb4Cu 0.8 Fe 70.8 Si 13.5 B 12 Nb3Cu 0.7 Fe 69.6 Si 14.5 B9P2Nb4Cu 0.9 Fe 69.8 Si 14.5 B9C2Nb4Cu 0.7 Fe 59.7 Co 10 Si 15.5 B 10 Nb4Cu 0.8 or Fe 64.7 Ni5Si 15.5 B 10 Nb4Cu0.8 The specific preferred composition of the Fe-based nanocrystalline soft magnetic powder described above is beneficial to improving the high-temperature stability and mechanical reliability of the composite material.

[0028] In one possible implementation, the FeNi soft magnetic powder is composed of: Fe 45.0 at.%~55.0 at.%, Ni 45 at.%~55 at.%. Limiting the atomic percentages of Fe and Ni in the FeNi soft magnetic powder to 45.0 at.%~55.0 at.% gives the FeNi powder high permeability, low coercivity, and excellent high-frequency magnetic stability, with low intrinsic eddy current loss. Simultaneously, this formulation of FeNi powder has high resistivity and good compatibility with Fe-based nanocrystalline soft magnetic powder. After compounding, it can fully utilize the synergistic effect of gradient particle size filling, effectively reducing high-frequency loss in the composite material and improving interparticle meshing, thus assisting in enhancing mechanical strength.

[0029] In one possible implementation, the thickness of the ZnO insulating layer is 50-200 nm. Limiting the thickness of the ZnO insulating layer to 50-200 nm ensures that the insulating layer is uniform, intact, and of moderate thickness, effectively blocking the eddy current path between particles while minimizing the dilution effect of non-magnetic relative magnetic properties.

[0030] Secondly, the present invention provides a method for preparing the above-mentioned soft magnetic composite material for high-frequency inductors, comprising the following steps: S1. Preparation of mixed magnetic powder: Fe-based nanocrystalline soft magnetic powder and FeNi soft magnetic powder are mixed at a mass ratio of 30:70 to 70:30, so that the FeNi soft magnetic powder fills the gaps between the Fe-based nanocrystalline soft magnetic powder to obtain mixed magnetic powder; In step S1, Fe-based nanocrystalline soft magnetic powder and FeNi soft magnetic powder are mixed at a mass ratio of 30:70 to 70:30. This ensures that the Fe-based nanocrystalline powder provides the core soft magnetic properties of the soft magnetic composite material, such as high permeability and high saturation magnetic induction, while also ensuring that the proportion of FeNi soft magnetic powder is sufficient to play a synergistic role in filling gaps, reducing losses, and enhancing mechanical properties. At the same time, it provides a structural basis for the subsequent ZnO insulating layer coating and molding curing. S2. Surface activation treatment: The mixed magnetic powder and silane coupling agent described in step S1 are ultrasonically dispersed in an organic solvent to obtain activated mixed magnetic powder; In step S2, active functional groups are introduced onto the surface of the mixed magnetic powder using a silane coupling agent, enhancing the chemical affinity between the powder surface and the ZnO precursor, promoting uniform nucleation and dense coating of ZnO on the powder surface, and improving the integrity and bonding strength of the insulating layer. An organic solvent serves as a dispersion medium, reducing the surface tension of the mixed magnetic powder and ensuring uniform coverage of all powder surfaces by the silane coupling agent. Ultrasonic dispersion breaks up soft powder agglomerates through cavitation, achieving sufficient particle dispersion and uniform adsorption of the silane coupling agent, providing uniform surface active sites for subsequent ZnO coating. Step S2 also improves the interfacial compatibility between the magnetic powder and subsequent coating layers and binders through chemical modification of the mixed magnetic powder surface.

[0031] S3, Insulating Layer Coating: The zinc salt precursor is dissolved in anhydrous ethanol, and the activated mixed magnetic powder described in step S2 is added. The mass of the zinc salt precursor is 1.5 wt.%~2.0 wt.% of the total mass of the mixed magnetic powder. The pH is adjusted to 8~11, and the reaction is stirred under a water bath at 55~65 ℃ to generate nano-ZnO in situ and uniformly coat the surface of the mixed magnetic powder. After drying, ZnO-coated mixed magnetic powder is obtained. In step S3, after surface activation, the magnetic powder is grafted with active groups of silane coupling agent, which can adsorb and combine with zinc ions during the in-situ ZnO generation process, allowing ZnO nuclei to grow directionally on the magnetic powder surface. This is beneficial for the in-situ and uniform coating of the insulating layer on the magnetic powder surface. The zinc salt precursor accounts for 1.5 wt.%~2.0 wt.% of the total mass of the mixed magnetic powder, which can form a continuous and dense nano-ZnO insulating layer on the magnetic powder surface, blocking the conductive path between magnetic powder particles and suppressing eddy current loss between particles. The alkaline range of pH 8~11 is the optimal reaction environment for the hydrolysis and condensation of the zinc salt precursor to generate ZnO nuclei, resulting in nano-sized ZnO with a dense and uniform coating layer. Stirring the reaction under ℃ water bath conditions provides stable and uniform reaction conditions, allowing the hydrolysis products of the zinc salt precursor to fully contact the surface of each magnetic powder particle, ensuring the uniformity of the ZnO insulating layer coating on the magnetic powder surface. The ZnO insulating layer is directly generated on the surface of the magnetic powder through solution phase chemical reaction, resulting in extremely strong adhesion between the coating layer and the magnetic powder surface, making it difficult to fall off. Compared with physical mixing coating, this significantly improves the coating stability and durability of the insulating layer, which is conducive to maintaining good insulation effect in long-term use and suppressing high-frequency eddy current loss.

[0032] S4. Adhesive Composite: Dissolve the adhesive in an organic solvent, add the ZnO-coated mixed magnetic powder obtained in step S3, ultrasonically disperse and continuously stir until the organic solvent is completely evaporated, and then vacuum dry to obtain the composite powder. In step S4, dissolving the binder in an organic solvent can reduce the binder viscosity and achieve molecular-level dispersion of the binder, ensuring the uniformity of the magnetic powder subsequently coated with ZnO. The surface of the magnetic powder after being coated with ZnO has good interfacial compatibility and can fully combine with the binder solution. The binder is uniformly deposited on the surface of the magnetic powder through solvent evaporation. Vacuum drying removes residual solvent and air bubbles, improving the density and insulation reliability of the composite material. This provides a bonding basis for subsequent molding and curing, and the binder can also form a double insulation structure with the ZnO insulation layer, further blocking the conductive path between magnetic powder particles and strengthening the high-frequency anti-eddy current loss capability.

[0033] S5. Molding and curing: The composite powder described in step S4 is cold-pressed at room temperature under a pressure of 500~700 MPa to obtain a molded blank; the molded blank is cured at 180~220 ℃ to obtain a soft magnetic composite material for high-frequency inductors.

[0034] In step S5, the powder is densified at room temperature using a pressure of 500~700 MPa. This pressure range is lower than that of hot pressing (usually >800 MPa), but a high-density preform can be obtained by utilizing the filling effect of the bimodal particle size distribution and the lubricating effect of ZnO. Room temperature cold pressing avoids the influence of the high temperature of hot pressing on the pre-curing of ZnO insulation layer and binder, maintaining the processing adaptability and microstructure integrity of the material. A curing temperature of 180~220 ℃ is used, which is lower than the ZnO grain growth temperature (~300 ℃) and nanocrystalline annealing temperature (~400 ℃), to achieve full cross-linking and curing of the binder, forming a three-dimensional network structure, and giving the composite material the final mechanical strength and magnetic stability.

[0035] The method for preparing soft magnetic composite materials for high-frequency inductors provided by the present invention, through the synergistic cooperation of the above five steps, simplifies the process, reduces energy consumption, and prepares a soft magnetic composite material that combines high-frequency low-loss stability and high-voltage crushing strength.

[0036] In one possible implementation, the organic solvent is anhydrous ethanol or acetone. Anhydrous ethanol and acetone have good solubility for silane coupling agents and zinc salt precursors, and moderate volatility, facilitating subsequent drying and removal. Furthermore, they do not chemically react with the magnetic powder, ensuring the stability and safety of the surface treatment process.

[0037] In one possible implementation, the mass of the silane coupling agent in step S2 is 0.8 wt.% to 1.2 wt.% of the mass of the mixed magnetic powder. This range of coupling agent dosage is beneficial for forming a complete and uniform active layer on the surface of the mixed magnetic powder, ensuring sufficient reaction with the ZnO precursor while avoiding insulation degradation or magnetic property dilution caused by excessive coupling agent residue.

[0038] In one possible implementation, the drying temperature in step S3 is 60-80 °C and the drying time is 8-12 h. These drying conditions allow the ZnO precursor hydrolysis products and solvents to fully evaporate, forming a dense and uniform ZnO insulating layer.

[0039] In one possible implementation, the zinc salt precursor in step S3 is zinc acetate dihydrate or zinc nitrate. Zinc acetate dihydrate and zinc nitrate readily hydrolyze to Zn(OH)2 under weakly alkaline conditions, and are mildly converted to ZnO at around 60 °C. The reaction is well controllable, produces uniform film, and the byproducts are easy to wash away, making it suitable for industrial production.

[0040] In one possible implementation, the room temperature cold pressing time in step S5 is 3-5 min, and the curing time is 0.8-1.2 h. The 3-5 min holding time allows the powder to be fully densified and stress relaxed, while the 0.8-1.2 h curing time allows the binder to be fully cross-linked. The two work together to achieve a short-cycle, high-efficiency preparation process.

[0041] The technical solution of the present invention will be further described below with reference to specific embodiments and comparative examples. All reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing. The instruments used in the embodiments are also commercially available.

[0042] Example 1 This embodiment provides a soft magnetic composite material for high-frequency inductors, which is composed of mixed magnetic powder, a ZnO insulating layer, and a binder; the mixed magnetic powder consists of 70 wt.% Fe. 69.7 Si 15.5 B 10 Nb4Cu 0.8 Nanocrystalline soft magnetic powder and 30 wt.% Fe 50 Ni 50 The mixture is composed of soft magnetic powder. The ZnO insulating layer is coated on the surface of the mixed magnetic powder by chemical co-precipitation. The mass of the ZnO precursor used to deposit the ZnO insulating layer is 1.75 wt.% of the mass of the mixed magnetic powder. The thickness of the ZnO insulating layer is about 100 nm. The binder is epoxy resin, and the mass of the binder is 3 wt.% of the total mass of the mixed magnetic powder.

[0043] The soft magnetic composite material for high-frequency inductors provided in this embodiment is prepared through the following steps: S1. Prepare the mixed magnetic powder: Adjust the median particle size... D 50 Fe = 28 μm 69.7 Si 15.5 B 10 Nb4Cu 0.8Nanocrystalline soft magnetic powder and median particle size D 50 FeNi50 powder with a particle size of 4 μm (Ni content 50 wt.%) was mixed at a mass ratio of 70:30, so that the FeNi powder filled the Fe... 69.7 Si 15.5 B 10 Nb4Cu 0.8 Mixed magnetic powder is obtained in the interstices of nanocrystalline powder; S2. Surface activation treatment: The mixed magnetic powder from step S1 and a propane coupling agent accounting for 1.0 wt.% of the total mass of the mixed magnetic powder are placed in anhydrous ethanol and ultrasonically dispersed for 30 min to obtain activated mixed magnetic powder. S3. Insulation Coating: Zinc acetate dihydrate (1.75 wt.% of the mixed magnetic powder) was dissolved in anhydrous ethanol and ultrasonically dispersed completely. This solution was then added dropwise to the stirred mixed magnetic powder. Deionized water was added, and the pH was adjusted to 9.0 using ammonia. The mixture was reacted in a 60 °C water bath for 120 min to allow nano-ZnO to form in situ and uniformly coat the surface of the mixed magnetic powder. After the reaction, the powder was washed three times with deionized water and dried at 60 °C for 10 h to obtain a mixed magnetic powder with a ZnO insulating layer approximately 100 nm thick. S4. Adhesive composite: 3.0 wt.% of epoxy resin by weight of mixed magnetic powder is dissolved in acetone, ultrasonically dispersed, and then the above-mentioned mixed magnetic powder coated with ZnO insulating layer is added. The mixture is stirred until the acetone is completely evaporated, and then dried in a vacuum oven at 60 °C for 1 h to obtain composite powder. S5. Molding and curing: The composite powder obtained in step S4 is cold-pressed at room temperature under a pressure of 600 MPa for 4 min, and then cured under vacuum at 200 ℃ for 1 h to obtain a soft magnetic composite material.

[0044] Example 2 This embodiment provides a soft magnetic composite material for high-frequency inductors, which differs from Embodiment 1 in that: the Fe content in the mixed magnetic powder is... 69.7 Si 15.5 B 10 Nb4Cu 0.8 The mass ratio of nanocrystalline soft magnetic powder to FeNi50 powder was 50:50, and all other aspects were the same as in Example 1.

[0045] Example 3 This embodiment provides a soft magnetic composite material for high-frequency inductors, which differs from Embodiment 1 in that: the Fe content in the mixed magnetic powder is... 69.7 Si 15.5 B 10 Nb4Cu 0.8 The mass ratio of nanocrystalline soft magnetic powder to FeNi50 powder was 30:70, and all other aspects were the same as in Example 1.

[0046] Example 4 This embodiment provides a soft magnetic composite material for high-frequency inductors, which differs from Embodiment 1 in that: the Fe content in the mixed magnetic powder is... 69.7 Si 15.5 B 10 Nb4Cu 0.8 The mass ratio of nanocrystalline soft magnetic powder to FeNi50 powder is 35:65. The binder is silicone resin, and the mass of the binder is 2.5 times the total mass of the mixed magnetic powder. All other aspects are the same as in Example 1.

[0047] Example 5 This embodiment provides a soft magnetic composite material for high-frequency inductors, which differs from Embodiment 1 in that: the Fe content in the mixed magnetic powder is... 69.6 Si 14.5 B9P2Nb4Cu 0.9 The mass ratio of nanocrystalline soft magnetic powder to FeNi50 powder is 40:60. The binder is phenolic resin, and the mass of the binder is 3.5 wt.% of the total mass of the mixed magnetic powder. All other aspects are the same as in Example 1.

[0048] Example 6 This embodiment provides a soft magnetic composite material for high-frequency inductors, which differs from Embodiment 1 in that: the Fe content in the mixed magnetic powder is... 69.8 Si 14.5 B9C2Nb4Cu 0.7 The mass ratio of nanocrystalline soft magnetic powder to FeNi50 powder was 60:40, and all other aspects were the same as in Example 1.

[0049] Example 7 This embodiment provides a soft magnetic composite material for high-frequency inductors, which differs from Embodiment 1 in that: the Fe content in the mixed magnetic powder is... 69.7 Si 15.5 B 10 Nb4Cu 0.8 The mass ratio of nanocrystalline soft magnetic powder to FeNi50 powder was 65:45, and all other aspects were the same as in Example 1.

[0050] Example 8 This embodiment provides a soft magnetic composite material for high-frequency inductors, which differs from Embodiment 3 in that the mixed magnetic powder is made of Fe. 59.7 Co 10 Si 15.5 B 10 Nb4Cu 0.8 Nanocrystalline soft magnetic powder and Fe 45 Ni 55 The powders were mixed in a mass ratio of 65:45, Fe 59.7 Co 10 Si15.5 B 10 Nb4Cu 0.8 Median particle size of nanocrystalline soft magnetic powder D 50 26 μm, Fe 45 Ni 55 Median particle size of powder D 50 The thickness is 5 μm, and everything else is the same as in Example 3.

[0051] Example 9 This embodiment provides a soft magnetic composite material for high-frequency inductors, which differs from Embodiment 3 in that the mixed magnetic powder is made of Fe. 64.7 Ni5Si 15.5 B 10 Nb4Cu 0.8 Nanocrystalline soft magnetic powder and Fe 55 Ni 45 The powders were mixed in a mass ratio of 65:45, Fe 64.7 Ni5Si 15.5 B 10 Nb4Cu 0.8 Median particle size of nanocrystalline soft magnetic powder D 50 30 μm, Fe 55 Ni 45 Median particle size of powder D 50 The thickness is 5 μm, and everything else is the same as in Example 3.

[0052] Example 10 This embodiment provides a soft magnetic composite material for high-frequency inductors. The difference from Embodiment 3 is that the mass of zinc acetate dihydrate in step S3 is 2 wt.% of the mass of the mixed magnetic powder, and the thickness of the ZnO insulating layer is about 200 nm. All other aspects are the same as in Embodiment 3.

[0053] Example 11 This embodiment provides a soft magnetic composite material for high-frequency inductors. The difference from Embodiment 3 is that the zinc salt precursor in step S3 is zinc nitrate, the mass of zinc nitrate is 1.5 wt.% of the mass of the mixed magnetic powder, and the thickness of the ZnO insulating layer is about 50 nm. All other aspects are the same as in Embodiment 3.

[0054] Example 12 This embodiment provides a soft magnetic composite material for high-frequency inductors. The difference from Embodiment 3 is that the mass of the silane coupling agent in step S2 is 0.8 wt.% of the mass of the mixed magnetic powder, and the pH value in step S3 is 8. The reaction is carried out under a water bath at 65 ℃. All other aspects are the same as in Embodiment 3.

[0055] Example 13 This embodiment provides a soft magnetic composite material for high-frequency inductors. The difference from Embodiment 3 is that the mass of the silane coupling agent in step S3 is 1.2 wt.% of the mass of the mixed magnetic powder, the pH value in step S3 is 11, and the reaction is carried out under a water bath at 55 ℃. All other aspects are the same as in Embodiment 3.

[0056] Example 14 This embodiment provides a soft magnetic composite material for high-frequency inductors. The difference between this embodiment and Embodiment 3 is that the pressure for room temperature cold pressing in step S5 is 500 MPa, and the curing temperature under vacuum is 180 °C. All other aspects are the same as in Embodiment 3.

[0057] Example 15 This embodiment provides a soft magnetic composite material for high-frequency inductors. The difference between this embodiment and Embodiment 3 is that the pressure for room temperature cold pressing in step S5 is 550 MPa, and the curing temperature under vacuum is 190 °C. All other aspects are the same as in Embodiment 3.

[0058] Example 16 This embodiment provides a soft magnetic composite material for high-frequency inductors. The difference between this embodiment and Embodiment 3 is that the pressure for room temperature cold pressing in step S5 is 650 MPa, and the curing temperature under vacuum is 210 °C. All other aspects are the same as in Embodiment 3.

[0059] Example 17 This embodiment provides a soft magnetic composite material for high-frequency inductors. The difference between this embodiment and Embodiment 3 is that the pressure for room temperature cold pressing in step S5 is 700 MPa, and the curing temperature under vacuum is 220 °C. All other aspects are the same as in Embodiment 3.

[0060] Example 18 This embodiment provides a soft magnetic composite material for high-frequency inductors, which differs from Embodiment 3 in that: Fe 69.7 Si 15.5 B 10 Nb4Cu 0.8 Median particle size of nanocrystalline soft magnetic powder D 50 The median particle size of the FeNi50 powder is 35 μm, and the median particle size is 12 μm. All other parameters are the same as in Example 3.

[0061] Example 19 This embodiment provides a soft magnetic composite material for high-frequency inductors, which differs from Embodiment 3 in that: Fe 69.7 Si 15.5 B 10 Nb4Cu 0.8 Median particle size of nanocrystalline soft magnetic powder D 50The median particle size of FeNi50 powder is 20 μm, and the median particle size is 2 μm. All other parameters are the same as in Example 3.

[0062] Comparative Example 1 This comparative example provides a soft magnetic composite material for high-frequency inductors, which differs from Example 1 in that the mixed magnetic powder composition is 100 wt.% Fe. 69.7 Si 15.5 B 10 Nb4Cu 0.8 The nanocrystalline soft magnetic powder is the same as in Example 1.

[0063] Comparative Example 2 This comparative example provides a soft magnetic composite material for high-frequency inductors, which differs from Example 1 in that the mixed magnetic powder composition is 100 wt.% Fe. 50 Ni5 soft magnetic powder, and everything else is the same as in Example 1.

[0064] Comparative Example 3 This comparative example provides a soft magnetic composite material for high-frequency inductors, prepared according to the method in Example 1 of patent document CN117936217A, wherein the Fe-based nanocrystalline powder accounts for 50%, the FeNi powder accounts for 50%, and an organosilicon resin (3%) + silane coupling agent (0.4%) is used as an insulating binder. The hot pressing is performed at a temperature of 180 ℃ and a pressure of 800 MPa; the annealing treatment is performed at a temperature of 450 ℃ and a time of 1 h.

[0065] Performance testing methods: Microstructure: The microstructure of the cross-section of the soft magnetic composite material was observed using a scanning electron microscope (SEM).

[0066] Permeability testing: The permeability of the soft magnetic composite material as a function of frequency was tested using an Agilent 4294A impedance analyzer.

[0067] Loss test: The soft magnetic composite material magnetic ring sample was wound (20 turns for the primary winding and 5 turns for the secondary winding), and the volume loss of the magnetic ring at different frequencies was tested using an Iwasaki 8218 AC hysteresis looper.

[0068] Saturation magnetic flux density test: The saturation magnetic flux density of the soft magnetic composite material was tested using a Lakeshore 7410 Vibrating Sample Magnetometer (VSM).

[0069] Crushing strength test: The crushing strength of the soft magnetic composite material was tested using a universal testing machine.

[0070] Test results: Figure 1This is a SEM image of the soft magnetic composite material used in Example 1. It can be clearly observed from the image that the Fe used in Example 1... 69.7 Si 15.5 B 10 Nb4Cu 0.8 (median particle size) D 50 Approximately 28 μm) and FeNi50 soft magnetic powder (median particle size) D 50 Approximately 4 μm, a typical bimodal particle size distribution structure was formed. Small-diameter FeNi powder effectively filled the large-diameter Fe particles. 69.7 Si 15.5 B 10 Nb4Cu 0.8 The triangular gaps significantly improve the packing density of the composite material. Figure 1 The areas marked by the yellow dashed circle represent residual gaps that have not yet been fully filled. This microstructural feature ensures that the material maintains excellent mechanical properties (compressive strength > 2300 kPa) and soft magnetic properties even under low-pressure cold pressing. Furthermore, the presence of burr-like roughness on the particle surface indicates the adhesion of ZnO nanoparticles to the surface; the presence of gray transition regions between particles indicates that the ZnO insulating layer fills the gaps, rather than direct metal contact; and the absence of metal sintering necks between particles proves that the ZnO inorganic insulating layer effectively blocks metal contact between particles, providing a structural basis for reducing high-frequency eddy current losses.

[0071] Figure 2 The graphs show the permeability of the soft magnetic composite materials in Examples 1-3 and Comparative Examples 1-2 as a function of frequency. The results show that the soft magnetic composite materials using the ZnO inorganic insulating system in Examples 1-3 maintain excellent permeability stability within the 10 MHz frequency range. Specifically, Example 1 (70% Fe-based nanocrystals) exhibits permeability fluctuations of less than ±2% in the 10 kHz to 2 MHz range, while Example 3 (30% Fe-based nanocrystals) achieves a permeability of 27.1 at 100 kHz. Particularly noteworthy is the higher permeability of Example 3 (27.1) compared to the pure FeNi system in Comparative Example 2 (24.4), demonstrating the synergistic enhancement effect of the bimodal particle size distribution structure. Compared with existing technologies that use silicone resin insulation (Comparative Example 3), although the permeability of soft magnetic composite materials for high-frequency inductors is lower in the low-frequency range (<100 kHz), they exhibit better stability in the high-frequency range (>500 kHz). The high resistivity and high thermal conductivity of ZnO effectively suppress high-frequency eddy current losses, so that the permeability remains stable over a wider frequency range, which is the core requirement for high-frequency inductor applications.

[0072] Figure 3The graphs show the loss versus frequency curves of the soft magnetic composite materials in Examples 1-3 and Comparative Examples 1-2, with a fixed magnetic flux density of 200 mT. The results show that the loss of the soft magnetic composite material in this application gradually increases with increasing frequency, but at the same frequency, the loss of Examples 1-3 is significantly lower than that of Comparative Example 1. In particular, Example 3 (30% Fe-based nanocrystals + 70% FeNi) exhibits a loss as low as 900.4 mW / cm² at 2000 kHz. 3 Achieved <1000 mW / cm 3 The invention achieves a leading level of performance, reducing losses by 71% compared to Comparative Example 1 (pure nanocrystals) and even by 6% compared to the pure FeNi system (Comparative Example 2). This unexpected technical effect stems from the synergistic effect of the ZnO inorganic insulating layer and the bimodal particle size distribution structure: small-particle-size FeNi powder fills the gaps between large-particle-size nanocrystals, effectively blocking eddy current paths and reducing hysteresis losses, while the ZnO insulating layer further improves high-frequency resistivity. Compared to existing technologies using silicone resin insulation (Comparative Example 3), this invention significantly reduces losses in the high-frequency range (>500 kHz), and the preparation process does not require high-temperature annealing, reducing energy consumption by more than 40%.

[0073] Figure 4 The VSM curves of the soft magnetic composite materials in Examples 1-3 and Comparative Examples 1-2 show the relationship between saturation magnetic induction (Bs) and the applied magnetic field. All samples exhibit the typical narrow hysteresis loop characteristics of soft magnetic materials. Comparative Example 2 (100% FeNi) has the highest Bs (~1.19 T), while pure FeNi has excessively high permeability (…). Figure 2 Insufficient crushing strength Figure 5 This material cannot be used alone. Comparative Example 1 (100% nanocrystals) had the lowest Bs (~0.94 T), mainly due to the high porosity and poor compressibility of the single nanocrystal system. Example 3 of this application (30% Fe-based nanocrystals + 70% FeNi) achieved Bs = 1.16 T, close to the level of pure FeNi, with a reduction of only 2.5%, demonstrating the efficient retention of Bs by the bimodal particle size distribution structure. The Bs range of Examples 1-3 is 1.05-1.16 T, meeting the requirements of high-frequency inductors for high saturation magnetic induction (>1.0 T). Compared with the prior art using a high-temperature annealing process (Comparative Example 3), although the Bs of this application is slightly lower, the preparation temperature is reduced from 450 °C to 200 °C, resulting in a significant reduction in energy consumption.

[0074] Figure 5The chart shows a comparison of the crush strength of the soft magnetic composite materials in Examples 1-3 and Comparative Examples 1-2. The radial compression method was used to apply a radial load to the toroidal magnetic powder core samples until failure. The results show that Comparative Example 1 (100% Fe-based nanocrystals) has the lowest crush strength (~1431 kPa), mainly due to the high hardness, poor compressibility, and high porosity of the nanocrystal powder. Example 3 (30% Fe-based nanocrystals + 70% FeNi) has the highest crush strength (~2915 kPa), an increase of 107% compared to Comparative Example 1 and 26% compared to Comparative Example 2 (pure FeNi, ~2305 kPa), demonstrating the significant enhancing effect of the bimodal particle size distribution structure on mechanical properties. The crush strength range of Examples 1-3 is 2334-2915 kPa, all meeting the mechanical requirements for industrial automated winding (>2000 kPa). Compared with existing technologies (which require hot pressing and high-temperature annealing in Comparative Example 3), this application uses a cold pressing process at 600 MPa and 200 °C for low-temperature curing, achieving higher strength with lower energy consumption and a simpler process. The performance data of the soft magnetic composite materials in Examples 1-3 and Comparative Examples 1-2 are shown in Table 1: Table 1 Performance data of soft magnetic composite materials in Examples 1-3 and Comparative Examples 1-2 As shown in Table 1, this application, through the synergistic design of the ZnO inorganic insulating layer and the Fe-based nanocrystal / FeNi bimodal particle size distribution structure, achieved a magnetic permeability of 22.7–27.1, a saturation magnetic induction of 1.05–1.16 T, and a high-frequency loss of 900.4–1386.6 mW / cm² within an optimized ratio range of 30–70%. 3 An excellent balance between 2 MHz and crushing strength of 2334~2915 kPa is achieved. Example 3 shows a loss of 900.4 mW / cm² at 2000 kHz. 3 Breaking 1000 mW / cm 3 It meets the industry threshold, with a crushing strength of 2914.9 kPa reaching the industry-leading level. Moreover, the preparation process does not require high-temperature annealing, reducing energy consumption by more than 53%, and has significant industrial practical value and green manufacturing advantages.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A soft magnetic composite material for high-frequency inductors, characterized in that, It is composed of mixed magnetic powder, a ZnO insulating layer, and a binder; the mixed magnetic powder consists of 30 wt.%~70 wt.% Fe-based nanocrystalline soft magnetic powder and the balance FeNi soft magnetic powder, wherein the median particle size of the Fe-based nanocrystalline soft magnetic powder and the FeNi soft magnetic powder is... D 50 The ZnO insulating layer is coated onto the surface of the mixed magnetic powder by chemical co-precipitation, with a ratio of 3:1 to 10:

1. The mass of the ZnO precursor used to deposit the ZnO insulating layer is 1.5 wt.% to 2.0 wt.% of the mass of the mixed magnetic powder. The binder is selected from one or more of epoxy resin, silicone resin and phenolic resin, and the mass of the binder is 2.5 wt.% to 3.5 wt.% of the total mass of the mixed magnetic powder.

2. The soft magnetic composite material for high-frequency inductors according to claim 1, characterized in that, The median particle size of the Fe-based nanocrystalline soft magnetic powder D 50 The median particle size of the FeNi soft magnetic powder is 20~35 μm. D 50 The value is 2~12 μm.

3. The soft magnetic composite material for high-frequency inductors according to claim 1, characterized in that, The Fe-based nanocrystalline soft magnetic powder in the mixed magnetic powder has a mass percentage content of 30 wt.% to 40 wt.%.

4. The soft magnetic composite material for high-frequency inductors according to claim 1, characterized in that, The Fe-based nanocrystalline soft magnetic powder is a Fe-Si-B-Cu-Nb series nanocrystalline soft magnetic powder.

5. The soft magnetic composite material for high-frequency inductors according to claim 4, characterized in that, The Fe-based nanocrystalline soft magnetic powder comprises: Fe 59.7 at.%~70.8 at.%, Si 13.5 at.%~15.5 at.%, B 9.0 at.%~12.0 at.%, Cu 0.7 at.%~0.9 at.%, Nb 3 at.%~4.0 at.%, and selectively added Co 10 at.%~11 at.%, P 2 at.%~3 at.%, C 2 at.%~3 at.%, or Ni 4 at.%~5 at.%.

6. The soft magnetic composite material for high-frequency inductors according to claim 5, characterized in that, The atomic percentage composition formula of the Fe-based nanocrystalline soft magnetic powder is: Fe 69.7 Si 15.5 B 10 Nb4Cu 0.8 Fe 70.8 Si 13.5 B 12 Nb3Cu 0.7 Fe 69.6 Si 14.5 B9P2Nb4Cu 0.9 Fe 69.8 Si 14.5 B9C2Nb4Cu 0.7 Fe 59.7 Co 10 Si 15.5 B 10 Nb4Cu 0.8 or Fe 64.7 Ni5Si 15.5 B 10 Nb4Cu 0.8 .

7. The soft magnetic composite material for high-frequency inductors according to claim 1, characterized in that, The FeNi soft magnetic powder has the following composition: Fe 45.0 at.%~55.0 at.%, Ni 45 at.%~55 at.%.

8. The soft magnetic composite material for high-frequency inductors according to claim 1, characterized in that, The thickness of the ZnO insulating layer is 50~200 nm.

9. A method for preparing a soft magnetic composite material for high-frequency inductors according to any one of claims 1-8, characterized in that, Includes the following steps: S1. Preparation of mixed magnetic powder: Fe-based nanocrystalline soft magnetic powder and FeNi soft magnetic powder are mixed at a mass ratio of 30:70 to 70:30, so that the FeNi soft magnetic powder fills the gaps between the Fe-based nanocrystalline soft magnetic powder to obtain mixed magnetic powder; S2. Surface activation treatment: The mixed magnetic powder and silane coupling agent described in step S1 are ultrasonically dispersed in an organic solvent to obtain activated mixed magnetic powder; S3, Insulating Layer Coating: The zinc salt precursor is dissolved in anhydrous ethanol, and the activated mixed magnetic powder described in step S2 is added. The mass of the zinc salt precursor is 1.5 wt.%~2.0 wt.% of the total mass of the mixed magnetic powder. The pH is adjusted to 8~11, and the reaction is stirred under a water bath at 55~65 ℃ to generate nano-ZnO in situ and uniformly coat the surface of the mixed magnetic powder. After drying, ZnO-coated mixed magnetic powder is obtained. S4. Adhesive Composite: Dissolve the adhesive in an organic solvent, add the ZnO-coated mixed magnetic powder obtained in step S3, ultrasonically disperse and continuously stir until the organic solvent is completely evaporated, and then vacuum dry to obtain the composite powder. S5. Molding and curing: The composite powder described in step S4 is cold-pressed at room temperature under a pressure of 500~700 MPa to obtain a molded blank; the molded blank is cured at 180~220 ℃ to obtain a soft magnetic composite material.

10. The method for preparing the soft magnetic composite material for high-frequency inductors according to claim 9, characterized in that, The organic solvent is anhydrous ethanol or acetone; And / or, the mass of the silane coupling agent in step S2 is 0.8 wt.% to 1.2 wt.% of the mass of the mixed magnetic powder; And / or, the drying temperature in step S3 is 60~80 ℃ and the time is 8~12 h; And / or, the time for room temperature cold pressing in step S5 is 3~5 min, and the curing time is 0.8~1.2 h.

Images