Modified metal magnetic powder, and preparation method therefor and use thereof

Abstract

The present disclosure relates to the technical field of magnetic materials. Disclosed are a modified metal magnetic powder, and a preparation method therefor and the use thereof. By using a T-unit siloxane as a raw material, a polysiloxane layer is formed on the surface of a metal magnetic powder; then by means of a drying treatment, the polysiloxane layer is in a low-moisture-content state, thereby promoting the condensation of silanol groups, such that organic groups of the T-unit siloxane are arranged in order, and a uniform polysiloxane layer is formed; and finally, the organic groups of the T-unit siloxane are removed by means of a calcination treatment, such that the uniform polysiloxane layer is converted into a compact siloxane compound layer. The modified metal magnetic powder that can be obtained thereby has a low water content after being placed.

Description

A modified metallic magnetic powder, its preparation method and application Technical Field

[0001] This invention relates to the field of magnetic materials technology, and in particular to a modified metal magnetic powder, its preparation method, and its application. Background Technology

[0002] With the rapid development of microelectronics and communication technologies, electronic components are increasingly moving towards miniaturization, energy saving, and high frequency. This places higher demands on the electrical performance, magnetic properties, and stability of electronic components, while losses at high frequencies are a major obstacle to their application.

[0003] Magnetic powder cores typically employ surface insulation modification to reduce eddy current losses. This surface modification aims to reduce charge concentration on the powder particles, preventing the generation of eddy currents within the particles under high-frequency magnetic fields. Such eddy currents would cause short circuits between the particles, leading to a sharp increase in eddy current losses, higher power losses in the inductor, and even overheating and circuit burnout.

[0004] Existing methods for surface insulation modification of magnetic powder mainly include organic and inorganic insulation coating. In organic insulation coating, organic insulating agents such as epoxy resin, phenolic resin, and silicone resin are used as binders to give the pressed powder inductor the required shape, size, and strength. Organic coating agents have good adhesive properties, but their poor heat resistance makes it difficult to eliminate internal stress in the magnetic core, limiting the heat treatment temperature of the magnetic powder core. In inorganic insulation coating, high-resistivity mineral powders, silicates, and a wide variety of oxides are mainly used as inorganic coating agents. Due to their advantages such as high heat treatment temperature, high resistivity, and low cost, they are widely used in the insulation coating modification of magnetic powders.

[0005] Currently, inorganic coated magnetic powder is used to modify its surface for insulation, but it is difficult to coat the magnetic powder evenly. Incomplete coating poses a risk of conduction between magnetic powder particles at high frequencies.

[0006] Phosphating, the most widely used surface insulation modification method, is disclosed in patent CN110181036A, which describes a composite soft magnetic metal powder. This method involves dissolving phosphoric acid in a volatile organic solvent (such as acetone or alcohol), mixing the soft magnetic powder with the phosphoric acid solution to produce a phosphating reaction, forming a phosphating film on the surface of the soft magnetic powder, and passivating the powder. Subsequently, an insulating agent and binder are added to create an insulating coating. However, the insulating coating formed by this method is prone to incompleteness and unevenness, leading to a decrease in the resistivity of the inductor and a risk of conduction at high frequencies. Furthermore, because it is a solvent reaction, it easily introduces a large amount of moisture into the soft magnetic powder, resulting in a high moisture content in the soft magnetic powder product. This drastically increases the risk of conduction during the operation of electronic components.

[0007] Another example is the method of using silica-coated magnetic powder with high resistivity and excellent thermal stability to modify its surface for insulation. Patent CN110767441A discloses a method for preparing FeSiBCr / SiO2 nanocrystalline soft magnetic composite iron core. This method controls the hydrolysis and polycondensation reaction rate of tetraethyl orthosilicate (TEOS) by controlling process parameters such as the amount of silicon source added, reaction temperature, water content, and ammonia content in the chemical liquid phase in-situ deposition process, so as to form a uniform and continuous SiO2 insulating shell. However, the insulating shell prepared by this method also has the problem of high water content. In addition, the reaction time of this patent is too long, making it unsuitable for industrial mass production. Summary of the Invention

[0008] To address the aforementioned technical problems in surface insulation modification of metal magnetic powder, this invention provides a modified metal magnetic powder, its preparation method, and its application.

[0009] First, this invention provides a modified metal magnetic powder having a core-shell structure with the metal magnetic powder as the core and a siloxane compound as the shell. The high resistivity of the siloxane compound is utilized to make the surface of the modified metal magnetic powder insulating; and it is then incorporated into the solid... 29 In the Si-NMR nuclear magnetic resonance spectrum, the ratio of the peak integral area in the range of -80ppm to -120ppm to the range of +20ppm to -120ppm is 50 to 99.5:100. When used in the semiconductor field, it can have a low water absorption rate after long-term storage, which can reduce the water content of the modified metal magnetic powder after long-term storage and avoid the risk of the modified metal magnetic powder particles becoming conductive due to the presence of moisture.

[0010] Secondly, the present invention provides a method for preparing modified metal magnetic powder. By selecting the best raw materials and optimizing the preparation process, the siloxane compound formed on the surface of the metal magnetic powder is more continuous and dense, and has a low water content after being left for a long time.

[0011] Furthermore, this invention provides the application of modified metal magnetic powder as a filler in the preparation of packaging materials or inductor materials in the semiconductor field.

[0012] The specific technical solution of this invention is as follows: Firstly, this invention provides a modified metal magnetic powder. The special feature of the modified metal magnetic powder provided by this invention is that it has a core-shell structure with metal magnetic powder as the core and a siloxane compound as the shell; in solid... 29 In the Si-NMR nuclear magnetic resonance spectrum, the ratio of the peak integral area of ​​the modified metal magnetic powder in the range of -80ppm to -120ppm to the range of +20ppm to -120ppm is 50 to 99.5:100.

[0013] In the semiconductor field, in order to reduce the eddy current loss of magnetic powder cores, it is necessary to perform insulation modification on the surface of the magnetic powder to avoid the generation of eddy currents inside the magnetic powder particles under high-frequency magnetic fields.

[0014] Therefore, based on the above problems, the present invention provides a modified metal magnetic powder with a core-shell structure of metal magnetic powder as the core and siloxane compound as the shell. By utilizing the high resistivity characteristics of siloxane compound, the modified metal magnetic powder can reduce charge concentration on the surface of the magnetic powder particles, thus preventing the modified metal magnetic powder from being conducted at high frequencies.

[0015] This invention modifies metal magnetic powder in solids 29 In the Si-NMR nuclear magnetic resonance spectrum, the ratio of the peak integrated area in the range of -80ppm to -120ppm to the range of +20ppm to -120ppm is 50 to 99.5:100.

[0016] In the semiconductor field, fillers are generally not used directly after preparation; they have a shelf life and therefore absorb moisture during storage. The modified metal magnetic powder provided by this invention absorbs less moisture after storage, which has a significant advantage in reducing the conductivity risk caused by high moisture content.

[0017] In the modified metal magnetic powder of this invention, to ensure that the siloxane compound is uniformly coated on the surface of the metal magnetic powder, the amount of a specific siloxane compound needs to be within a certain range. If the amount of the siloxane compound is too small, it cannot completely coat the surface of the metal magnetic powder, resulting in a discontinuous shell and high porosity, which can lead to water absorption problems later. If the modified metal magnetic powder has too much water content, ion precipitation will occur, and the risk of conductive bonding between magnetic powder particles will increase, affecting the operation of electronic devices. If the amount of the siloxane compound is too large, the modified metal magnetic powder will agglomerate, making it difficult to mix evenly with the resin. The mixed filler formed by the product and the resin will peel off, which will also increase the formation of pores in the mixed filler of metal magnetic powder and resin, causing water absorption problems. Therefore, this invention provides a modified metal magnetic powder, which in solid form... 29 In the Si-NMR nuclear magnetic resonance spectrum, the ratio of the peak integrated area in the range of -80ppm to -120ppm to the range of +20ppm to -120ppm is 50 to 99.5:100.

[0018] Preferably, the siloxane compound is prepared from a siloxane containing at least 90% wt% T units. Wherein, T units = R1SiO3-, and R1 is a hydrogen atom or a hydrocarbon group consisting of 1 to 16 carbon atoms, which can be independently selected.

[0019] Inorganic coating of magnetic powder involves surface insulation modification, but uniform coating is difficult, and incomplete coating poses a risk of conductivity between powder particles at high frequencies. The modified metal magnetic powder shell provided by this invention exhibits high density and good continuity. The siloxane compound film prepared using polysiloxane containing at least 90% wt T units exhibits high density and good continuity. To coat the metal magnetic powder, the silanol groups of the siloxane need to condense, forming a polysiloxane film on the surface of the magnetic powder. This is followed by heat treatment to obtain the siloxane compound. During the formation of the polysiloxane film, since T-unit molecules rotate more freely than Q-unit molecules, the modified metal magnetic powder film of this invention needs to be prepared using polysiloxane containing at least 90% wt T units to achieve the advantage of low water absorption after placement.

[0020] Further preferred, the T-unit siloxane is selected from hydrocarbon-trialkoxysilane and hydrocarbon-trichlorosilane.

[0021] Preferably, the thickness of the shell is 0.5 nm to 300 nm.

[0022] Preferably, the modified metal magnetic powder provided by the present invention, after being placed in an environment of 25°C and 50% RH for 48 hours, has a Karl Fischer moisture content at 200°C not exceeding 150 ppm / m. 2 .

[0023] If there is moisture in the metal magnetic powder, there is a risk of electrical conduction. At the same time, the presence of moisture can cause metal ions to leach out, which can affect the operation of electronic devices.

[0024] Because the modified metal magnetic powder provided by this invention has a dense and continuous siloxane compound shell, it has the excellent characteristic of low water absorption after storage, which can reduce the water absorption of the metal magnetic powder during the shelf life. As a filler for electronic devices, it can make the device have a lower risk of conduction during operation. At the same time, the surface insulation of the modified metal magnetic powder can reduce eddy current loss.

[0025] Secondly, the present invention provides a method for preparing the above-mentioned modified metal magnetic powder, comprising the following steps: Step S1, adding T-unit siloxane to the metal magnetic powder and reacting it to form polysiloxane on the surface of the metal magnetic powder, thereby obtaining a precursor; Step S2, performing a drying treatment to bring the precursor to a low moisture content state; Step S3, performing a calcination treatment to densify the surface of the precursor, thereby obtaining modified metal magnetic powder; wherein, T-unit = R1SiO3-, R1 is a hydrogen atom or a hydrocarbon group of 1 to 16 independently selectable carbon atoms, and the modified metal magnetic powder has a dense siloxane compound shell.

[0026] To reduce the loss of magnetic powder cores, the surface of the metal magnetic powder is typically modified for insulation. The most common method in existing technologies is to use inorganic insulating coating agents for this modification. However, existing inorganic coating methods for magnetic powder often fail to achieve uniform coating, leading to incomplete coating and the risk of conduction between powder particles at high frequencies. Furthermore, current coating modifications typically do not consider water absorption or moisture content. In the semiconductor field, both fillers and inductor materials are generally not used directly after preparation and have a shelf life; therefore, it is crucial to monitor water absorption during storage and moisture content after storage.

[0027] To improve the density of the siloxane compound film layer of metal magnetic powder and reduce the water absorption of the product after placement, this invention provides a method for preparing the modified metal magnetic powder as described above, forming a uniform and dense siloxane compound film layer on the surface of the metal magnetic powder. First, this invention uses T-unit siloxane raw materials to form a polysiloxane layer on the surface of the metal magnetic powder; then, through drying, the polysiloxane layer is brought to a low moisture content state, promoting the condensation of silanol groups and causing the organic groups of the T-unit siloxane to arrange in an orderly manner, forming a uniform polysiloxane layer, which is beneficial for the formation of a dense siloxane compound; finally, through calcination, some of the organic groups of the T-unit siloxane are removed, transforming the uniform polysiloxane layer into a dense siloxane compound shell layer.

[0028] The conditions for forming a dense siloxane compound shell on the surface of metal magnetic powder according to the present invention include the following three aspects: ① Because T-unit siloxanes are polar, they can be quickly adsorbed onto the surface of metal magnetic powder when mixed with it, forming a polysiloxane film. Therefore, the first condition of the preparation method of the present invention is to use T-unit siloxanes as raw materials. Since T-unit molecules can rotate freely relatively easily, the first condition of using T-unit siloxanes as raw materials is a prerequisite for step S2 of the present invention to promote the rotation and optimize the arrangement of the organic groups of siloxanes by keeping the polysiloxane film in a low moisture content state.

[0029] ② The second condition of the preparation method of this invention is drying to bring the polysiloxane layer to a low moisture content state, which promotes the rotation and orderly arrangement of the organic groups of the T-unit siloxane, thus forming a uniform polysiloxane layer. A uniform polysiloxane layer is beneficial to the formation of a uniform and dense siloxane compound layer. ③ The third condition is to remove the organic groups of the polysiloxane layer by calcination, making it dense. Under this condition, the uniform polysiloxane layer is transformed into a uniform and dense siloxane compound shell layer.

[0030] As a preferred embodiment of the above preparation method, in step S1, the particle size of the metal magnetic powder is 0.05–40 μm.

[0031] To form a uniform siloxane compound shell on the surface of metal magnetic powder, the particle size of the metal magnetic powder needs to be within the range of 0.05–40 μm. If the particle size of the metal magnetic powder is too small, it is prone to agglomeration, making it difficult for T-unit siloxane to be uniformly adsorbed on the surface of the metal magnetic powder. Therefore, it is difficult to form a uniform polysiloxane film, resulting in incomplete coating and poor coating effect. Since the thickness of the siloxane compound to be coated is small, less T-unit siloxane raw material is added. If the particle size of the metal magnetic powder is too large, the siloxane will also have the problem of being difficult to uniformly adsorb on the surface of the metal magnetic powder, resulting in uneven coating and high porosity. If the coating thickness and the amount of added siloxane raw material are increased to promote uniform coating, the resulting metal magnetic powder will agglomerate. Agglomeration will make it difficult for the modified metal magnetic powder to mix evenly with the resin, and the mixed filler formed by the product and the resin will peel off. This will also increase the formation of pores in the mixed filler of metal magnetic powder and resin, causing water absorption problems.

[0032] Preferably, in step S1, the mass ratio of the metal magnetic powder to the added T-unit siloxane is 100:0.2 to 10.

[0033] As a preferred embodiment of the above preparation method, in step S1, an alkaline aqueous solution is added to carry out the reaction.

[0034] Step S1 involves the adsorption of T-unit siloxane onto the surface of the metal magnetic powder to form a polysiloxane film. Adding an alkaline aqueous solution promotes the condensation of silanol groups. The alkaline aqueous solution can be one or more of the following: ammonia, tetramethylammonium hydroxide, choline, ethylenediamine, isopropylamine, and ethanolamine.

[0035] Further optimization involves adding silica powder in step S1 to carry out the reaction.

[0036] Further preferred, the particle size of the silica powder is 10–100 nm.

[0037] To further improve the density of the siloxane compound shell, this invention also adds nano-silica powder during the formation of the polysiloxane shell in step S1. The siloxane compound coated on the surface of the metal magnetic powder in this invention can be primarily derived from T-unit siloxane raw materials, with a small portion being directly added nano-silica powder. During the condensation of siloxanes to form polysiloxanes, the mixture is not dense. During the reaction, a small amount of silica powder is added and dispersed within the polysiloxane framework. In step S3, when the organic groups of the polysiloxane are removed by calcination, this silica powder can fill the positions of the organic groups, reducing the porosity of the siloxane compound shell coated on the surface of the metal magnetic powder. The preferred particle size of the silica powder is 10–100 nm, and the preferred amount added is 0.5%–1.2% of the mass of T-unit siloxane raw materials.

[0038] As a preferred embodiment of the above preparation method, in step S2, the drying treatment reduces the water content of the precursor to 0.1-1%.

[0039] Maintaining a low moisture content in the polysiloxane layer promotes the rotation and orderly arrangement of the organic groups within the T-unit siloxane, resulting in a uniform polysiloxane layer. This leads to a denser and more uniform siloxane compound shell, ultimately resulting in lower water absorption and moisture content in the product after storage. The highest density of the siloxane compound shell formed on the surface of the metal magnetic powder is achieved when the precursor moisture content is between 0.1% and 1%.

[0040] As a preferred method of the above preparation method, the drying treatment method is: heating to 50-200℃ and drying for 6-24 hours.

[0041] As a preferred embodiment of the above preparation method, in step S3, the calcination treatment is carried out under an inert gas atmosphere.

[0042] As a preferred embodiment of the above preparation method, in step S3, the calcination temperature is 600–1200°C and the time is 6–72 hours.

[0043] The purpose of calcination is to remove the organic groups of the T-unit siloxane, transforming the uniform polysiloxane layer into a dense siloxane compound layer. Calcination is carried out in an inert gas atmosphere, which provides superior densification. The preferred treatment temperature is 600–1200℃, and the preferred treatment time is 6–72 hours.

[0044] Thirdly, the present invention also provides the application of the above-mentioned modified metal magnetic powder in the preparation of semiconductor packaging materials or inductor materials.

[0045] In the semiconductor field, assembling passive components, semiconductor components, electroacoustic devices, display devices, optical devices, and radio frequency devices into equipment requires circuit board substrate materials such as high-density interconnect boards, high-frequency and high-speed boards, and motherboards. These substrate materials are generally composed mainly of fillers and organic polymers such as resins. Applying the modified metal magnetic powder provided by this invention to the preparation of semiconductor packaging materials or substrate materials can effectively meet the heat dissipation requirements of semiconductor packaging materials or substrate materials.

[0046] Compared with the prior art, the present invention has the following technical effects: (1) The present invention provides a modified metal magnetic powder with a core-shell structure of metal magnetic powder as the core and siloxane compound as the shell, which can be used in solid... 29In the Si-NMR nuclear magnetic resonance spectrum, the ratio of the peak integral area of ​​the modified metal magnetic powder of this invention in the range of -80ppm to -120ppm to the range of +20ppm to -120ppm is 50 to 99.5:100. The modified metal magnetic powder of this invention can undergo insulating modification of the metal magnetic powder surface using siloxane compounds, reducing eddy current losses in the magnetic powder core. Furthermore, the modified metal magnetic powder of this invention also has the excellent characteristic of low water absorption after storage, which can reduce the water absorption of the modified metal magnetic powder during its shelf life and reduce the conduction risk caused by high water content at high frequencies.

[0047] (2) This invention uses T-unit siloxane raw materials to form a polysiloxane layer on the surface of metal magnetic powder; then, through drying treatment, the polysiloxane layer is brought to a low moisture content state, promoting the condensation of silanol groups and causing the organic groups of the T-unit siloxane to arrange in an orderly manner, forming a uniform polysiloxane layer; finally, through calcination treatment, some of the organic groups of the T-unit siloxane are removed and converted into Q units, transforming the uniform polysiloxane layer into a dense siloxane compound shell. Therefore, this invention provides a metal magnetic powder with a continuous, dense siloxane compound shell, which absorbs little water after being placed. Detailed Implementation

[0048] The present invention will be further described below with reference to embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0049] The particle moisture content was measured at 200 degrees Celsius using a Karl Fischer moisture analyzer (Mitsubishi Chemical CA-310) and the coulometric method. In the performance testing, the unit for water content was ppm / m³. 2 The calculation is to divide the measured moisture content by the geometric external surface area of ​​the test sample particles (calculated based on the measured average particle size).

[0050] The average particle size was measured using a Beckman Coulter LS-13320 laser particle size analyzer with deionized water as the solvent. In this paper, the average particle size refers to the volume average diameter of the particles.

[0051] In siloxane compounds 29In the Si-NMR nuclear magnetic resonance spectrum, the total content of groups bonded to Si is represented by the peak integral area in the range of +20ppm to -120ppm, and the content of Q units is represented by the peak integral area in the range of -80ppm to -120ppm. The modified metal magnetic powder particles provided by this invention have a peak integral area ratio of 50 to 99.5:100 in the range of -80ppm to -120ppm to +20ppm.

[0052] The thickness of the modified metal magnetic powder siloxane compound coating, i.e. the thickness of the modified metal magnetic powder shell, was obtained by high-resolution transmission electron microscopy.

[0053] Example 1 provides a modified metal magnetic powder with a continuous, dense siloxane compound shell, prepared as follows: Step S1: Methyltrimethoxysilane (MTMS) is added to metal magnetic powder with an average particle size of 0.5 μm, and after uniform mixing, 5% ammonia water (by volume) is added, and the reaction is carried out at 25°C to form polysiloxane on the surface of the metal magnetic powder, thus obtaining a precursor. The mass ratio of metal magnetic powder, MTMS, and 5% ammonia water (by volume) is 50:1:1.

[0054] Step S2: Place the precursor obtained in step S1 into a muffle furnace and heat it to 70°C for 24 hours for drying, so that the precursor is in a low moisture content state with a water content of 0.8%.

[0055] Step S3: Nitrogen gas is introduced into the muffle furnace to create a nitrogen atmosphere. The furnace is then heated to 750°C at a rate of 5°C / min and held for 6 hours for calcination to densify the precursor surface. The precursor is then cooled to room temperature in the furnace to obtain modified metal magnetic powder with a continuous and dense siloxane compound coating. The coating thickness of the siloxane compound is 2.0 nm.

[0056] Example 2 provides a modified metal magnetic powder with a continuous, dense siloxane compound shell, prepared as follows: Step S1: Methyltrimethoxysilane (MTMS) is added to metal magnetic powder with an average particle size of 0.5 μm, and after uniform mixing, 5% ammonia water (by volume) is added, and the reaction is carried out at 25°C to form polysiloxane on the surface of the metal magnetic powder, thus obtaining a precursor. The mass ratio of metal magnetic powder, MTMS, and 5% ammonia water (by volume) is 50:1:1.

[0057] Step S2: Place the precursor obtained in step S1 into a muffle furnace and heat it to 70°C for 24 hours for drying, so that the precursor is in a low moisture content state with a water content of 0.2%.

[0058] Step S3: Nitrogen gas is introduced into the muffle furnace to create a nitrogen atmosphere. The furnace is then heated to 750°C at a rate of 5°C / min and held for 6 hours for calcination to densify the precursor surface. The precursor is then cooled to room temperature in the furnace to obtain modified metal magnetic powder with a continuous and dense siloxane compound coating. The coating thickness of the siloxane compound is 2.3 nm.

[0059] Example 3 provides a modified metal magnetic powder with a continuous, dense siloxane compound shell, prepared as follows: Step S1: Methyltrimethoxysilane (MTMS) is added to metal magnetic powder with an average particle size of 0.5 μm, and after uniform mixing, 5% ammonia water (by volume) is added, and the reaction is carried out at 25°C to form polysiloxane on the surface of the metal magnetic powder, thus obtaining a precursor. The mass ratio of metal magnetic powder, MTMS, and 5% ammonia water (by volume) is 50:1:1.

[0060] Step S2: Place the precursor obtained in step S1 into a muffle furnace and heat it to 70°C for 24 hours for drying, so that the precursor is in a low moisture content state with a water content of 1%.

[0061] Step S3: Nitrogen gas is introduced into the muffle furnace to create a nitrogen atmosphere. The furnace is then heated to 750°C at a rate of 5°C / min and held for 6 hours for calcination to densify the precursor surface. The precursor is then cooled to room temperature in the furnace to obtain modified metal magnetic powder with a continuous and dense siloxane compound coating. The coating thickness of the siloxane compound is 2.0 nm.

[0062] Example 4 provides a modified metal magnetic powder with a continuous, dense siloxane compound shell, prepared as follows: Step S1: Methyltrimethoxysilane (MTMS) is added to metal magnetic powder with an average particle size of 1 μm, and after uniform mixing, 5% ammonia water (by volume) is added, and the reaction is carried out at 25°C to form polysiloxane on the surface of the metal magnetic powder, thus obtaining a precursor. The mass ratio of metal magnetic powder, MTMS, and 5% ammonia water (by volume) is 50:1:1.

[0063] Step S2: Place the precursor obtained in step S1 into a muffle furnace and heat it to 70°C for 24 hours for drying, so that the precursor is in a low moisture content state with a water content of 0.8%.

[0064] Step S3: Nitrogen gas is introduced into the muffle furnace to create a nitrogen atmosphere. The furnace is then heated to 750°C at a rate of 5°C / min and held for 6 hours for calcination to densify the precursor surface. The precursor is then cooled to room temperature in the furnace to obtain modified metallic magnetic powder with a continuous and dense siloxane compound coating. The coating thickness of the siloxane compound is 7.0 nm.

[0065] Example 5 provides a modified metal magnetic powder with a continuous, dense siloxane compound shell, prepared by the following method: Step S1, methyltrimethoxysilane (MTMS) is added to metal magnetic powder with an average particle size of 1.8 μm, and after uniform mixing, 5% ammonia water is added, and the reaction is carried out at 25°C to form polysiloxane on the surface of the metal magnetic powder, thus obtaining the precursor. The mass ratio of metal magnetic powder, MTMS, and 5% ammonia water is 50:1:1.

[0066] Step S2: Place the precursor obtained in step S1 into a muffle furnace and heat it to 70°C for 24 hours for drying, so that the precursor is in a low moisture content state with a water content of 0.8%.

[0067] Step S3: Nitrogen gas is introduced into the muffle furnace to create a nitrogen atmosphere. The furnace is then heated to 750°C at a rate of 5°C / min and held for 6 hours for calcination to densify the precursor surface. The precursor is then cooled to room temperature in the furnace to obtain modified metallic magnetic powder with a continuous and dense siloxane compound coating. The coating thickness of the siloxane compound is 24.0 nm.

[0068] Example 6 provides a modified metal magnetic powder with a continuous, dense siloxane compound shell, prepared by the following method: Step S1: Methyltrimethoxysilane (MTMS) is added to metal magnetic powder with an average particle size of 0.05 μm, and after uniform mixing, 5% ammonia water (by volume) is added, and the reaction is carried out at 25°C to form polysiloxane on the surface of the metal magnetic powder, thus obtaining a precursor. The mass ratio of metal magnetic powder, MTMS, and 5% ammonia water (by volume) is 50:1:1.

[0069] Step S2: Place the precursor obtained in step S1 into a muffle furnace and heat it to 70°C for 24 hours for drying, so that the precursor is in a low moisture content state with a water content of 0.8%.

[0070] Step S3: Nitrogen gas is introduced into the muffle furnace to create a nitrogen atmosphere. The furnace is then heated to 750°C at a rate of 5°C / min and held for 6 hours for calcination to densify the precursor surface. The precursor is then cooled to room temperature in the furnace to obtain modified metallic magnetic powder with a continuous and dense siloxane compound coating. The coating thickness of the siloxane compound is 0.5 nm.

[0071] Example 7 provides a modified metal magnetic powder with a continuous, dense siloxane compound shell, prepared as follows: Step S1: Methyltrimethoxysilane (MTMS) is added to a 40 μm layer, mixed thoroughly, and then 5% ammonia solution is added. The mixture is reacted at 25°C to form a polysiloxane on the surface of the metal magnetic powder, thus obtaining a precursor. The mass ratio of the metal magnetic powder, MTMS, and 5% ammonia solution is 50:1:1.

[0072] Step S2: Place the precursor obtained in step S1 into a muffle furnace and heat it to 70°C for 24 hours for drying, so that the precursor is in a low moisture content state with a water content of 0.8%.

[0073] Step S3: Nitrogen gas is introduced into the muffle furnace to create a nitrogen atmosphere. The furnace is then heated to 750°C at a rate of 5°C / min and held for 6 hours for calcination to densify the precursor surface. The precursor is then cooled to room temperature in the furnace to obtain modified metallic magnetic powder with a continuous and dense siloxane compound coating. The coating thickness of the siloxane compound is 260.1 nm.

[0074] Example 8 provides a modified metal magnetic powder with a continuous, dense siloxane compound shell, prepared by the following method: Step S1: Methyltrimethoxysilane (MTMS) is added to metal magnetic powder with an average particle size of 40 μm, and after uniform mixing, 5% ammonia water (by volume) is added, and the reaction is carried out at 25°C to form polysiloxane on the surface of the metal magnetic powder, thus obtaining a precursor. The mass ratio of metal magnetic powder, MTMS, and 5% ammonia water (by volume) is 45:1:1.

[0075] Step S2: Place the precursor obtained in step S1 into a muffle furnace and heat it to 70°C for 24 hours for drying, so that the precursor is in a low moisture content state with a water content of 0.8%.

[0076] Step S3: Nitrogen gas is introduced into the muffle furnace to create a nitrogen atmosphere. The furnace is then heated to 750°C at a rate of 5°C / min and held for 6 hours for calcination to densify the precursor surface. The precursor is then cooled to room temperature in the furnace to obtain modified metallic magnetic powder with a continuous and dense siloxane compound coating. The coating thickness of the siloxane compound is 300.0 nm.

[0077] Example 9 provides a modified metal magnetic powder with a continuous, dense siloxane compound shell, prepared by the following method: Step S1: Methyltrimethoxysilane (MTMS) is added to metal magnetic powder with an average particle size of 10 μm. After mixing evenly, ammonia water with a volume concentration of 5% and nano-silica powder are added. The reaction is carried out at 25°C to form polysiloxane on the surface of the metal magnetic powder, thus obtaining a precursor. The mass ratio of metal magnetic powder, MTMS, ammonia water with a volume concentration of 5% and nano-silica powder is 50:3:3:0.01. The average particle size of the nano-silica powder is 30 nm.

[0078] Step S2: Place the precursor obtained in step S1 into a muffle furnace and heat it to 70°C for 24 hours for drying, so that the precursor is in a low moisture content state with a water content of 0.8%.

[0079] Step S3: Nitrogen gas is introduced into the muffle furnace to create a nitrogen atmosphere. The furnace is then heated to 650°C at a rate of 5°C / min and held for 6 hours for calcination to densify the precursor surface. The precursor is then cooled to room temperature in the furnace to obtain modified metallic magnetic powder with a continuous and dense siloxane compound coating. The coating thickness of the siloxane compound is 127.1 nm.

[0080] Example 10 provides a modified metal magnetic powder with a continuous, dense siloxane compound shell, prepared by the following method: Step S1: Methyltrimethoxysilane (MTMS) is added to metal magnetic powder with an average particle size of 10 μm. After mixing evenly, ammonia water with a volume concentration of 5% and nano-silica powder are added. The reaction is carried out at 25°C to form polysiloxane on the surface of the metal magnetic powder, thus obtaining a precursor. The mass ratio of metal magnetic powder, MTMS, ammonia water with a volume concentration of 5% and nano-silica powder is 50:3:3:0.01. The average particle size of the nano-silica powder is 10 nm.

[0081] Step S2: Place the precursor obtained in step S1 into a muffle furnace and heat it to 70°C for 24 hours for drying, so that the precursor is in a low moisture content state with a water content of 0.8%.

[0082] Step S3: Nitrogen gas is introduced into the muffle furnace to create a nitrogen atmosphere. The furnace is then heated to 650°C at a rate of 5°C / min and held for 6 hours for calcination to densify the precursor surface. The precursor is then cooled to room temperature in the furnace to obtain modified metallic magnetic powder with a continuous and dense siloxane compound coating. The coating thickness of the siloxane compound is 118.0 nm.

[0083] Example 11 provides a modified metal magnetic powder with a continuous, dense siloxane compound shell, prepared by the following method: Step S1: Methyltrimethoxysilane (MTMS) is added to metal magnetic powder with an average particle size of 10 μm. After mixing evenly, ammonia water with a volume concentration of 5% and nano-silica powder are added. The reaction is carried out at 25°C to form polysiloxane on the surface of the metal magnetic powder, thus obtaining a precursor. The mass ratio of metal magnetic powder, MTMS, ammonia water with a volume concentration of 5% and nano-silica powder is 50:3:3:0.01. The average particle size of the nano-silica powder is 100 nm.

[0084] Step S2: Place the precursor obtained in step S1 into a muffle furnace and heat it to 70°C for 24 hours for drying, so that the precursor is in a low moisture content state with a water content of 0.8%.

[0085] Step S3: Nitrogen gas is introduced into the muffle furnace to create a nitrogen atmosphere. The furnace is then heated to 650°C at a rate of 5°C / min and held for 6 hours for calcination to densify the precursor surface. The precursor is then cooled to room temperature in the furnace to obtain modified metallic magnetic powder with a continuous and dense siloxane compound coating. The coating thickness of the siloxane compound is 135.6 nm.

[0086] Example 12 provides a modified metal magnetic powder with a continuous, dense siloxane compound shell, prepared by the following method: Step S1: Methyltrimethoxysilane (MTMS) is added to metal magnetic powder with an average particle size of 10 μm. After mixing evenly, ammonia water with a volume concentration of 5% and nano-silica powder are added. The reaction is carried out at 25°C to form polysiloxane on the surface of the metal magnetic powder, thus obtaining a precursor. The mass ratio of metal magnetic powder, MTMS, ammonia water with a volume concentration of 5% and nano-silica powder is 50:3:3:0.01. The average particle size of the nano-silica powder is 7 nm.

[0087] Step S2: Place the precursor obtained in step S1 into a muffle furnace and heat it to 70°C for 24 hours for drying, so that the precursor is in a low moisture content state with a water content of 0.8%.

[0088] Step S3: Nitrogen gas is introduced into the muffle furnace to create a nitrogen atmosphere. The furnace is then heated to 650°C at a rate of 5°C / min and held for 6 hours for calcination to densify the precursor surface. The precursor is then cooled to room temperature in the furnace to obtain modified metallic magnetic powder with a continuous and dense siloxane compound coating. The coating thickness of the siloxane compound is 109.9 nm.

[0089] Example 13 provides a modified metal magnetic powder with a continuous, dense siloxane compound shell, prepared by the following method: Step S1: Methyltrimethoxysilane (MTMS) is added to metal magnetic powder with an average particle size of 10 μm. After mixing evenly, ammonia water with a volume concentration of 5% and nano-silica powder are added. The reaction is carried out at 25°C to form polysiloxane on the surface of the metal magnetic powder, thus obtaining a precursor. The mass ratio of metal magnetic powder, MTMS, ammonia water with a volume concentration of 5% and nano-silica powder is 50:3:3:0.01. The average particle size of the nano-silica powder is 120 nm.

[0090] Step S2: Place the precursor obtained in step S1 into a muffle furnace and heat it to 70°C for 24 hours for drying, so that the precursor is in a low moisture content state with a water content of 0.8%.

[0091] Step S3: Nitrogen gas is introduced into the muffle furnace to create a nitrogen atmosphere. The furnace is then heated to 650°C at a rate of 5°C / min and held for 6 hours for calcination to densify the precursor surface. The precursor is then cooled to room temperature in the furnace to obtain modified metallic magnetic powder with a continuous and dense siloxane compound coating. The coating thickness of the siloxane compound is 137.7 nm.

[0092] Example 14 provides a modified metal magnetic powder with a continuous, dense siloxane compound shell, prepared as follows: Step S1: Methyltrimethoxysilane (MTMS) is added to metal magnetic powder with an average particle size of 10 μm. After mixing evenly, ammonia water with a volume concentration of 5% and nano-silica powder are added. The mixture is reacted at 25°C to form polysiloxane on the surface of the metal magnetic powder, thus obtaining a precursor. The mass ratio of metal magnetic powder, MTMS, ammonia water with a volume concentration of 5% and nano-silica powder is 50:3:3:0.019. The average particle size of the nano-silica powder is 30 nm.

[0093] Step S2: Place the precursor obtained in step S1 into a muffle furnace and heat it to 50°C for 10 hours to dry it, so that the precursor is in a low moisture content state with a water content of 0.8%.

[0094] Step S3: Nitrogen gas is introduced into the muffle furnace to create a nitrogen atmosphere. The temperature is then increased to 1000℃ at a rate of 5℃ / min and held for 10 hours for calcination to densify the precursor surface. The precursor is then cooled to room temperature in the furnace to obtain modified metallic magnetic powder with a continuous and dense siloxane compound coating. The coating thickness of the siloxane compound is 125.5 nm.

[0095] Example 15 provides a modified metal magnetic powder with a continuous, dense siloxane compound shell, prepared by the following method: Step S1: Methyltrimethoxysilane (MTMS) is added to metal magnetic powder with an average particle size of 10 μm. After mixing evenly, ammonia water with a volume concentration of 5% and nano-silica powder are added. The reaction is carried out at 25°C to form polysiloxane on the surface of the metal magnetic powder, thus obtaining a precursor. The mass ratio of metal magnetic powder, MTMS, ammonia water with a volume concentration of 5%, and nano-silica powder is 100:6:6:0.01. The average particle size of the nano-silica powder is 30 nm.

[0096] Step S2: Place the precursor obtained in step S1 into a muffle furnace and heat it to 200°C for 6 hours to dry it, so that the precursor is in a low moisture content state with a water content of 0.8%.

[0097] Step S3: Nitrogen gas is introduced into the muffle furnace to create a nitrogen atmosphere. The temperature is then increased to 1200℃ at a rate of 5℃ / min and held for 24 hours for calcination to densify the precursor surface. The precursor is then cooled to room temperature in the furnace to obtain modified metal magnetic powder with a continuous and dense siloxane compound coating. The coating thickness of the siloxane compound is 115.6 nm.

[0098] The main difference between Comparative Example 1 and Example 1 is that the average particle size of the metal magnetic powder in step S1 is 0.02 μm. Everything else is the same as in Example 1.

[0099] The coating thickness of the siloxane compound measured in this comparative example was 1.2 nm.

[0100] The main difference between Comparative Example 2 and Example 1 is that the average particle size of the metal magnetic powder in step S1 is 46 μm. Everything else is the same as in Example 1.

[0101] The coating thickness of the siloxane compound measured in this comparative example was 320.2 nm.

[0102] The main difference between Comparative Example 3 and Example 1 is that the average particle size of the metal magnetic powder in step S1 is 46 μm; and the mass ratio of metal magnetic powder, MTMS, and ammonia water with a volume concentration of 5% in step S1 is 40:1:1. Everything else is the same as in Example 1.

[0103] The coating thickness of the siloxane compound measured in this comparative example was 450.4 nm.

[0104] The main difference between Comparative Example 4 and Example 1 is that the water content of the precursor in step S2 is 0.01%. Everything else is the same as in Example 1.

[0105] The coating thickness of the siloxane compound measured in this comparative example was 2.4 nm.

[0106] The main difference between Comparative Example 5 and Example 1 is that the water content of the precursor in step S2 is 1.2%. Everything else is the same as in Example 1.

[0107] The coating thickness of the siloxane compound measured in this comparative example was 2.1 nm.

[0108] The main difference between Comparative Example 6 and Example 1 is that the gas atmosphere used for calcination in step S3 is air. Everything else is the same as in Example 1.

[0109] The coating thickness of the siloxane compound measured in this comparative example was 2.3 nm.

[0110] The main difference between Comparative Example 7 and Example 1 is that the calcination temperature in step S3 is 600°C, and the holding time is 5 hours. Everything else is the same as in Example 1.

[0111] The coating thickness of the siloxane compound measured in this comparative example was 2.2 nm.

[0112] The main difference between Comparative Example 8 and Example 1 is that the calcination temperature in step S3 is 550°C, and the holding time is 6 hours. Everything else is the same as in Example 1.

[0113] The coating thickness of the siloxane compound measured in this comparative example was 2.3 nm.

[0114] Performance characterization was performed on the modified metal magnetic powders prepared in Examples 1-15 and Comparative Examples 1-8, testing for particle size, Q unit content, and moisture content after standing. The results are shown in Table 1. The moisture content after standing was determined by placing the powder in an open environment at 25°C and 50% RH for 48 hours from the point of preparation. Q unit content refers to the solid content of the modified metal magnetic powder. 29 The ratio of the peak integral area in the Si-NMR nuclear magnetic resonance spectrum in the range of -80ppm to -120ppm to the peak integral area in the range of +20ppm to -120ppm.

[0115] Table 1 As shown in Table 1: (1) As shown in Examples 1-15, this invention uses T-unit siloxane raw materials to form a polysiloxane layer on the surface of metal magnetic powder; then, through drying treatment, the polysiloxane layer is in a low moisture content state, promoting the condensation of silanol groups, and the organic groups of T-unit siloxane are arranged in an orderly manner to form a uniform polysiloxane layer, which is conducive to the formation of dense siloxane compounds; finally, through calcination treatment, some of the organic groups of T-unit siloxane are removed and converted into Q units, so that the uniform polysiloxane layer is converted into a dense siloxane compound layer. The modified metal magnetic powder obtained in this way has the excellent characteristic of low water content after storage. Since this modified metal magnetic powder is used in semiconductor fillers, it has a dense siloxane compound shell, which can reduce the water absorption of metal magnetic powder during shelf life, reduce the eddy current loss of magnetic powder core during operation of electronic devices, and reduce the risk of easy conduction between magnetic powder particles caused by high water content.

[0116] (2) Analysis of particle size selection conditions in the preparation method of modified metal magnetic powder of the present invention: From the comparison analysis between Comparative Examples 1 and 2 and Example 1, it can be seen that the particle sizes of the metal magnetic powders in Comparative Examples 1 and 2 are 0.02 μm and 46 μm, respectively, and their water content is greatly increased compared with Example 1. The reason for this is that if the particle size of the metal magnetic powder is too small, it is easy to agglomerate, and the T-unit siloxane is difficult to be uniformly adsorbed on the surface of the metal magnetic powder. Therefore, it is difficult to form a uniform polysiloxane film layer, resulting in poor coating effect. Since the thickness of the siloxane compound to be coated is small, the amount of T-unit siloxane raw material added is small. If the particle size of the metal magnetic powder is too large, the siloxane will also have the problem of being difficult to be uniformly adsorbed on the surface of the metal magnetic powder, resulting in uneven coating. Uneven coating will lead to increased water absorption after the product is placed. Therefore, the particle size of the metal magnetic powder needs to be controlled within a suitable range when preparing modified metal magnetic powder by the method of the present invention.

[0117] Furthermore, comparative analysis of the moisture content characterization data of Examples 1, 6-7, and Comparative Examples 1-2 shows that the preferred particle size of the metal magnetic powder of the present invention is 0.05-40 μm.

[0118] A comparative analysis of Example 8 with Examples 7 and 1 shows that the particle size of the metal magnetic powder in Example 7 is larger than that in Example 1. To increase the coating amount in Example 7 and thus improve the uniformity and density of the coating film, the amount of added T-unit siloxane can be increased. For example, Example 8 increased the amount of added siloxane, and its coating uniformity was better than that of Example 7 (reflected in the lower water absorption of Example 8). However, comparing Comparative Example 3 with Comparative Example 2, when the particle size of the metal magnetic powder in Comparative Example 2 increased to 46 μm, despite the addition of siloxane in Comparative Example 3, the water absorption of Comparative Example 3 was greater than that of Comparative Example 2. Furthermore, agglomeration of the metal magnetic powder was observed during the preparation process. It is speculated that excessive addition of T-unit siloxane will increase the viscosity of the metal magnetic powder, preventing the siloxane from being uniformly adsorbed on the surface of the metal magnetic powder to form a polysiloxane film, ultimately leading to a decrease in the density of the siloxane compound film obtained by calcination. Therefore, it is further speculated that in order to form a uniform and dense shell of siloxane compounds and to reduce the water content of the product, this method needs to control the particle size of the metal magnetic powder within a certain range.

[0119] (3) Analysis of the precursor moisture content in the preparation method of the modified metal magnetic powder of the present invention: A comparison of Comparative Examples 4-5 with Example 1 shows that the moisture content of the precursors after drying in Comparative Examples 4 and 5 is 0.01% and 1.2%, respectively. The moisture content of the modified metal magnetic powder products obtained from these examples is significantly higher than that of Example 1 after placement. Therefore, keeping the moisture content of the precursor within a certain range is beneficial for the formation of dense siloxane compounds. The preferred moisture content of the precursor is a low moisture content of 0.1% to 1%. The reason for this is that keeping the polysiloxane layer in a low moisture content state of 0.1% to 1% promotes the rotation and orderly arrangement of the organic groups of the T-unit siloxane, resulting in a uniform polysiloxane layer. This leads to a denser siloxane compound shell with lower porosity.

[0120] (4) Analysis of the calcination gas atmosphere conditions in the preparation method of the modified metal magnetic powder of the present invention: A comparison between Comparative Example 6 and Example 1 shows that the gas atmosphere for the calcination treatment in step S3 of Comparative Example 6 was air, and the water content of Comparative Example 6 increased significantly after placement. The reason for this is that air contains the active gas oxygen, which reacts with the carbon formed by the decomposition of organic groups. After carrying away the carbon, defects are formed at the carbon sites, resulting in high porosity, a non-dense shell, and high water absorption in the product. When calcination is carried out in an inert atmosphere, although the water released by the condensation of silanols also reacts with carbon and carries away the carbon, the water content is low, so the rate of carbon removal is slow. The continuous condensation of silanols in the film can repair the defect sites, resulting in low porosity and ultimately low water content in the product.

[0121] (5) Analysis of the conditions for the Q unit content of the product in the preparation method of the modified metal magnetic powder of the present invention: Comparative analysis of Comparative Examples 7-8 and Example 1 shows that Comparative Examples 7 and 8, by adjusting the temperature and time of the calcination step, reduced the conversion of T units to Q units, resulting in Q unit contents of 47.0% and 42.1% for the products of Comparative Examples 7 and 8, respectively. The moisture content of the modified metal magnetic powder obtained after standing was 195.4 ppm / m³, respectively. 2 274.6ppm / m 2 The moisture content increased significantly. Therefore, it can be seen that the modified metal magnetic powder provided by this invention controls the Q unit content within a certain range, resulting in a low moisture content in the modified metal magnetic powder after storage.

[0122] (6) Analysis of the conditions for adding nano-silica during the preparation process of the modified metal magnetic powder of the present invention: A comparison of Examples 9-11 with Example 1 shows that nano-silica with different particle sizes and contents was added during the preparation process of Examples 9-11. After placement, the water content decreased to varying degrees, indicating that the addition of nano-silica can improve the density of the prepared siloxane compound film. The reason for this is that when siloxanes condense to form polysiloxanes, the polysiloxane is not dense. During the reaction, a small amount of silica powder is added and dispersed in the polysiloxane skeleton. When the polysiloxane organic groups are removed by calcination in step S3, this silica powder can effectively fill the positions of the organic groups, improving the density of the siloxane compound shell coating on the surface of the metal magnetic powder. Furthermore, comparing Examples 9-11 with Examples 12-13, it can be seen that the particle size of the nano-silica powder needs to be 10-100nm; otherwise, it cannot fill the polysiloxane skeleton. For example, Example 12 cannot function, and its water content is not significantly lower than that of Example 1. The silica particles added in Example 13 are too large, which will destroy the continuity of the shell and ultimately result in a large water content.

[0123] The metal magnetic powder used in the embodiments of the present invention was purchased from Shenzhen Platinum New Materials Co., Ltd.

[0124] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0125] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A modified metallic magnetic powder, characterized in that: The modified metal magnetic powder has a core-shell structure with metal magnetic powder as the core and siloxane compound as the shell; In the solid state 29 In the Si-NMR nuclear magnetic resonance spectrum, the ratio of the peak integral area in the range of -80 ppm to -120 ppm to the peak integral area in the range of +20 ppm to -120 ppm of the modified metal magnetic powder is 50.0-99.5:

100.

2. The modified metal magnetic powder as described in claim 1, characterized in that: The modified metal magnetic powder has a Karl Fischer moisture at 200°C of no more than 150 ppm / m after being left in an environmental condition of 25°C, 50% RH for 48 hours. 2 .

3. The modified metal magnetic powder as described in claim 1, characterized in that: The siloxane compound is prepared from siloxanes containing more than 90% wt T units; Wherein, T unit = R1SiO3-, R1 is a hydrogen atom or a hydrocarbon group of 1 to 16 carbon atoms that can be chosen independently.

4. The modified metal magnetic powder as described in claim 3, characterized in that: The T unit siloxane is selected from hydrocarbon-trialkoxysilane and hydrocarbon-trichlorosilane.

5. The modified metal magnetic powder as described in claim 1, characterized in that: The thickness of the shell ranges from 0.5 nm to 300 nm.

6. The method for preparing modified metal magnetic powder according to any one of claims 1 to 5, characterized in that: Includes the following steps: Step S1: Add T units of siloxane to the metal magnetic powder and react to form polysiloxane on the surface of the metal magnetic powder to obtain the precursor. Step S2: Perform drying treatment to bring the precursor to a low moisture content state; Step S3: Calcination treatment is performed to densify the surface of the precursor and obtain modified metal magnetic powder. Wherein, T unit = R1SiO3-, R1 is a hydrogen atom or a hydrocarbon group of 1 to 16 carbon atoms that can be independently selected, and the modified metal magnetic powder has a dense siloxane compound shell.

7. The method for preparing modified metal magnetic powder as described in claim 6, characterized in that: In step S1, an alkaline aqueous solution is added to carry out the reaction.

8. The method for preparing modified metal magnetic powder as described in claim 7, characterized in that: Silica powder was also added to the reaction.

9. The method for preparing modified metal magnetic powder as described in claim 8, characterized in that: The particle size of the silica powder is 10–100 nm.

10. The method for preparing modified metal magnetic powder as described in claim 6, characterized in that: In step S1, the particle size of the metal magnetic powder is 0.05–40 μm.

11. The method for preparing modified metal magnetic powder as described in claim 6, characterized in that: In step S2, the drying process reduces the moisture content of the precursor to 0.1-1%.

12. The method for preparing modified metal magnetic powder as described in claim 6 or 11, characterized in that: The drying process involves heating to 50–200°C and drying for 6–24 hours.

13. The method for preparing modified metal magnetic powder as described in claim 6, characterized in that: In step S3, the calcination process is carried out in an inert gas atmosphere.

14. The method for preparing modified metal magnetic powder as described in claim 6, characterized in that: In step S3, the calcination temperature is 600–1200℃.

15. The method for preparing modified metal magnetic powder as described in claim 14, characterized in that: In step S3, the calcination treatment time is 6 to 72 hours.

16. The application of the modified metal magnetic powder according to any one of claims 1 to 5, or the modified metal magnetic powder prepared by the preparation method according to any one of claims 6 to 15, in the preparation of semiconductor packaging materials or inductor materials.

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