Modified metal magnetic powder, and preparation method and application thereof

Abstract

The application relates to the technical field of magnetic materials, and discloses a modified metal magnetic powder and a preparation method and application thereof. The application forms a polysiloxane layer on the surface of the metal magnetic powder by using T unit siloxane raw materials; then the polysiloxane layer is in a state of low moisture content through drying treatment, the condensation of silicon hydroxyl groups is promoted, the organic groups of the T unit siloxane are orderly arranged, and a uniform polysiloxane layer is formed; finally, the organic groups of the T unit siloxane are removed through calcination treatment, the uniform polysiloxane layer is converted into a dense siloxane compound layer. The modified metal magnetic powder obtained in this way has excellent performance of low water content after being placed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of magnetic materials, in particular to a modified metal magnetic powder and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of microelectronics and communication technology, electronic components are increasingly developing towards miniaturization, energy saving, high frequency and other directions, which puts higher requirements on the electrical properties, magnetic properties and stability of electronic components. The loss at high frequency is a major obstacle to its application.

[0003] Magnetic powder cores usually adopt a method of insulating modification of the surface of the powder to reduce eddy current loss. The main purpose of insulating modification of the surface of the magnetic powder is to reduce the phenomenon of charge concentration on the surface of the magnetic powder particles, so as to avoid the generation of eddy current in the interior of the magnetic powder particles under a high-frequency magnetic field, make the magnetic powder particles conduct (regarded as short-circuit), and then cause the eddy current loss between the magnetic powder particles to increase sharply, the power loss of inductance to be large, and even the problem of heating to burn the circuit.

[0004] The existing methods of insulating modification of the surface of the magnetic powder mainly include organic insulating coating and inorganic insulating coating. In the organic insulating coating, an organic insulating coating agent such as epoxy resin, phenolic resin, organic silicon resin, etc. is used as an adhesive to make the inductor device after powder pressing have the required shape size and strength. The organic coating agent has good adhesion, but its heat resistance is poor, it is difficult to eliminate the stress in the magnetic core, and it limits the heat treatment temperature of the magnetic powder core. In the inorganic insulating coating process, mineral powder, silicate and various oxides with high resistivity are mainly used as inorganic coating agents. Due to the advantages of high heat treatment temperature, high resistivity and low cost, they are widely used in insulating coating modification of magnetic powder.

[0005] At present, the inorganic coated magnetic powder is difficult to uniformly coat the surface, and the incomplete coating makes the magnetic powder particles exist the risk of conduction at high frequency.

[0006] The most commonly used method of surface insulating modification is phosphating treatment. Patent CN110181036A discloses a kind of composite soft magnetic metal powder, which is prepared by dissolving phosphoric acid in a volatile organic solvent (such as acetone, alcohol, etc.), then 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 then adding an insulating agent and a binder for powder insulating coating. The insulating coating layer formed by this method is prone to be incomplete and uneven, the resistivity of the inductor is reduced, and there is a risk of conduction at high frequency. At the same time, since it is a solvent reaction, more water is introduced into the soft magnetic powder, and the water content of the soft magnetic powder product is high, which greatly increases the risk of conduction during the operation of the electronic component.

[0007] For example, a method for insulating modification of the surface of magnetic powder by coating the magnetic powder with high resistivity and silicon dioxide with good thermal stability. Patent CN110767441A discloses a preparation method of FeSiBCr / SiO2 nanocrystalline soft magnetic composite core. The method controls the hydrolysis and polycondensation reaction rate of tetraethyl orthosilicate (TEOS) by controlling the dropping amount of silicon source, 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, and the reaction time of this patent is too long, which is not suitable for industrial mass production. SUMMARY

[0008] In order to solve the above technical problems of surface insulating modification of metal magnetic powder, the present application provides a modified metal magnetic powder and its preparation method and application.

[0009] Firstly, the present application provides a modified metal magnetic powder having a core-shell structure with a metal magnetic powder as a core and a siloxane compound as a shell. The high resistivity of the siloxane compound makes the surface of the modified metal magnetic powder insulating. And the modified metal magnetic powder has a low water content after long time storage. 29 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 in the Si-NMR nuclear magnetic resonance spectrum is 50-99.5:100. The application can have a lower water absorption after long time storage in the semiconductor field, so that the modified metal magnetic powder has a lower water content after long time storage, avoiding the risk of conduction between the modified metal magnetic powder particles due to the presence of water.

[0010] Secondly, the present application provides a preparation method of modified metal magnetic powder. By optimizing the raw materials and 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 long time storage.

[0011] Thirdly, the present application provides the application of the modified metal magnetic powder as a filler in the preparation of packaging materials or inductance materials in the semiconductor field.

[0012] The specific technical solutions of the present application are as follows:

[0013] In the first aspect, the present application provides a modified metal magnetic powder. The modified metal magnetic powder provided by the present application has a core-shell structure with a metal magnetic powder as a core and a siloxane compound as a shell. The modified metal magnetic powder has a low water content after long time storage. 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 50-99.5:100.

[0014] In the semiconductor field, in order to reduce the eddy current loss of the magnetic powder core, the surface of the magnetic powder needs to be modified for insulation to avoid the generation of eddy current in the internal part of the magnetic powder particles under a high-frequency magnetic field.

[0015] Therefore, based on the above problems, the present application provides a modified metal magnetic powder with a core-shell structure having a metal magnetic powder as a core and a siloxane compound as a shell layer. Through the high resistivity characteristics of the siloxane compound, the modified metal magnetic powder can reduce the concentration of electric charges on the surface of the magnetic powder particles and avoid the conduction of the modified metal magnetic powder under high frequency.

[0016] The modified metal magnetic powder of the present application has a water content of 0.1% to 5% by mass in a solid state. 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 peak integral area in the range of +20ppm to -120ppm is 50-99.5:100.

[0017] In the semiconductor field, during the actual application process of the filler, the filler is generally not directly used after preparation and will have a shelf life, so it will absorb water during storage. The modified metal magnetic powder provided by the present application has a small amount of water absorption after storage, which has great advantages in reducing the risk of conduction caused by high water content.

[0018] In the modified metal magnetic powder of the present application, in order to make the siloxane compound uniformly wrapped on the surface of the metal magnetic powder, the amount of the specific siloxane compound needs to be within a certain range. If the amount of the siloxane compound is too small, the siloxane compound cannot completely wrap the surface of the metal magnetic powder, the shell layer is discontinuous and has high porosity, there will be a problem of water absorption later, the water content of the modified metal magnetic powder is too large, there will be a problem of ion precipitation, and the risk of conduction between the 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 have an agglomeration phenomenon, it is difficult to mix uniformly with the resin, and the mixed filler formed by the product and the resin will have a peeling phenomenon, which will also increase the formation of pores in the metal magnetic powder and resin mixed filler, causing water absorption problems. Therefore, the present application provides a modified metal magnetic powder, which has a water content of 0.1% to 5% by mass in a solid state. 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 peak integral area in the range of +20ppm to -120ppm is 50-99.5:100.

[0019] Preferably, the siloxane compound is prepared from a siloxane containing 90%wt or more T units. The T unit is R1SiO3-, and R1 is a hydrogen atom or a carbon atom 1 to 16 hydrocarbon group which can be independently selected.

[0020] The inorganic coated magnetic powder is difficult to be uniformly coated, and the incomplete coating causes the risk of conduction between the magnetic powder particles at high frequency. The siloxane compound shell of the modified metal magnetic powder provided by the application has high density and good continuity. The siloxane compound film prepared by using polysiloxane containing 90wt% or more T units as raw material has high density and good continuity. In order to coat the metal magnetic powder, the silanol of the siloxane needs to be condensed to form a polysiloxane film layer on the surface of the metal magnetic powder, and then the siloxane compound is obtained by heat treatment. During the formation of the polysiloxane film layer, the T unit molecules are more easily rotated than the Q unit molecules. Therefore, in order to form a uniform, continuous and dense film layer, the film layer of the modified metal magnetic powder provided by the application needs to be prepared by using polysiloxane containing 90wt% or more T units as raw material, so as to have the advantage of less water absorption after storage.

[0021] Further preferably, the T unit siloxane is selected from hydrocarbyl trialkoxysilane and hydrocarbyl trichlorosilane.

[0022] Preferably, the thickness of the shell layer is 0.5nm-300nm.

[0023] Preferably, the modified metal magnetic powder provided by the application has a Karl Fischer moisture content of not more than 150ppm / m2 at 200℃ after being stored at 25℃ and 50% RH for 48 hours. 2 .

[0024] The metal magnetic powder has moisture connection, which causes the risk of conduction, and the existence of moisture also causes the problem of metal ion precipitation, which affects the operation of electronic devices.

[0025] The modified metal magnetic powder provided by the application has a dense and continuous siloxane compound shell, so it has the excellent characteristic of less water absorption after storage, and can reduce the water absorption of the metal magnetic powder during the shelf life. When the modified metal magnetic powder is used as a filler of an electronic device, the operation of the electronic device has a lower risk of conduction, and the surface insulation of the modified metal magnetic powder can also reduce the eddy current loss.

[0026] In a second aspect, the application provides a preparation method of the modified metal magnetic powder, which comprises the following steps:

[0027] Step S1: adding T unit siloxane to the metal magnetic powder for reaction to form polysiloxane on the surface of the metal magnetic powder and obtain a precursor;

[0028] Step S2: drying treatment to make the precursor in a low moisture content state;

[0029] Step S3: calcination treatment to densify the surface of the precursor and obtain the modified metal magnetic powder;

[0030] wherein T unit = R1SiO3-, R1 is a hydrogen atom or a hydrocarbon group of carbon atoms 1 to 16 which can be independently selected, and the modified metal magnetic powder has a dense siloxane compound shell.

[0031] In order to reduce the loss of magnetic powder core, the surface of the metal magnetic powder is usually modified by insulation, and the most commonly used method in the prior art is to coat the surface of the metal magnetic powder with an inorganic insulation coating agent. However, the existing inorganic coated magnetic powder is difficult to uniformly coat the surface of the metal magnetic powder, and the incomplete coating causes the risk of conduction between the magnetic powder particles at high frequency. Moreover, the coating modification in the prior art does not consider the water absorption and water content, but in the semiconductor field, whether it is a filler or an inductor material, it is generally not directly used after preparation, and there is a shelf life, so the water absorption during storage and the water content after storage need to be concerned.

[0032] In order to improve the density of the siloxane compound film layer of the metal magnetic powder and reduce the water absorption of the product after storage, the present application provides a preparation method of the modified metal magnetic powder as described above, which forms a uniform and dense siloxane compound film layer on the surface of the metal magnetic powder. First, the present application forms a polysiloxane layer on the surface of the metal magnetic powder by using T unit siloxane raw material; then, the polysiloxane layer is in a low moisture content state by drying treatment, which promotes the condensation of silanol and the ordered arrangement of the organic groups of T unit siloxane, forming a uniform polysiloxane layer, which is conducive to the formation of a dense siloxane compound; finally, through calcination treatment, part of the organic groups of T unit siloxane are removed, and the uniform polysiloxane layer is converted into a dense siloxane compound shell.

[0033] The conditions for forming the dense siloxane compound shell on the surface of the metal magnetic powder of the present application include the following three aspects:

[0034] ① Since T unit siloxane has polarity, it can quickly adsorb on the surface of the metal magnetic powder when mixed with the metal magnetic powder to form a polysiloxane film layer. Therefore, the first condition of the preparation method of the present application is to use T unit siloxane raw material. Since the molecular free rotation of T unit is relatively easy, the first condition of using T unit siloxane as raw material is a prerequisite for the step S2 of the present application to promote the rotation of the organic groups of siloxane and optimize their arrangement by making the polysiloxane film layer in a low moisture content state.

[0035] ② The second condition of the preparation method of the present application is to dry the polysiloxane layer to a low moisture content state to promote the rotation of the organic groups of T unit siloxane and arrange them in order to form a uniform polysiloxane layer. The uniform polysiloxane layer is conducive to the formation of a uniform and dense siloxane compound layer,

[0036] (3) The third condition is to remove the organic group of the polysiloxane layer by calcination to densify it, and the uniform polysiloxane layer is converted into a uniform and dense siloxane compound shell layer under this condition.

[0037] As a preferred embodiment of the above preparation method, the particle size of the metal magnetic powder in step S1 is 0.05-40 μm.

[0038] To enable the formation of a uniform siloxane compound shell layer on the surface of the metal magnetic powder, the particle size of the metal magnetic powder needs to be in the range of 0.05-40 μm. 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 uniformly adsorb on the surface of the metal magnetic powder, so it is difficult to form a uniform polysiloxane film layer thereon, and the coating is incomplete and the coating effect is poor. Since the thickness of the siloxane compound to be coated is small, the amount of T unit siloxane raw material added is small, and 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. At this time, if the uniform coating is promoted by increasing the coating thickness and increasing the amount of siloxane raw material added, the obtained metal magnetic powder will have the phenomenon of agglomeration, which will make it difficult for the modified metal magnetic powder to be uniformly mixed with the resin, and the mixed filler formed by the product and the resin will have the phenomenon of peeling, which will also increase the formation of pores in the metal magnetic powder and resin mixed filler, causing water absorption problems.

[0039] As a preferred embodiment, the mass ratio of the metal magnetic powder to the added T unit siloxane in step S1 is 100:0.2-10.

[0040] As a preferred embodiment of the above preparation method, an alkaline aqueous solution is added for reaction in step S1.

[0041] Step S1 is a reaction in which the T unit siloxane is adsorbed on the surface of the metal magnetic powder to form a polysiloxane film layer, and the addition of an alkaline aqueous solution for reaction can promote the condensation of silanol groups. The alkaline aqueous solution can be one or more of an aqueous ammonia solution, a tetramethylammonium hydroxide solution, a choline solution, an ethylenediamine solution, an isopropylamine solution, and an ethanolamine solution.

[0042] Further preferably, a silica powder is also added for reaction in step S1.

[0043] Further preferably, the particle size of the silica powder is 10-100 nm.

[0044] In order to further improve the density of the siloxane compound shell, the present application also adds nano-silica powder when forming the polysiloxane shell in step S1. The siloxane compound coated on the surface of the metal magnetic powder is mostly prepared from T-unit siloxane raw material, and a small amount of nano-silica powder is directly added. When the siloxane is condensed to form polysiloxane, it is not dense. During the reaction, a small amount of silica powder is dispersed in the polysiloxane skeleton. When the organic group is removed by calcination in step S3, these silica powders 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 particle size of the silica powder is preferably 10-100 nm, and the amount added is preferably 0.5-1.2% of the mass of the T-unit siloxane raw material.

[0045] As a preferred embodiment of the above preparation method, in step S2, the drying treatment makes the water content of the precursor 0.1-1%.

[0046] By keeping the polysiloxane layer in a low moisture content state, the organic groups of the T-unit siloxane are rotated and arranged in order, forming a uniform polysiloxane layer, and the resulting siloxane compound shell is more dense and uniform, ultimately resulting in a product with less water absorption after storage and a low water content after storage. When the water content of the precursor is 0.1-1%, the siloxane compound shell formed on the surface of the metal magnetic powder has the highest density.

[0047] As a preferred embodiment of the above preparation method, the drying treatment method is to heat to 50-200°C and dry for 6-24 hours.

[0048] As a preferred embodiment of the above preparation method, in step S3, the calcination treatment is carried out in an inert gas atmosphere.

[0049] As a preferred embodiment of the above preparation method, in step S3, the calcination treatment is carried out in an inert gas atmosphere.

[0050] The effect of calcination treatment is to remove the organic groups of the T-unit siloxane and convert the uniform polysiloxane layer into a dense siloxane compound layer. Calcination treatment is carried out in an inert gas atmosphere, which has a better densification effect, and the treatment temperature is preferably 600-1200°C and the time is preferably 6-72 hours.

[0051] In a third aspect, the present application also provides the use of the modified metal magnetic powder described above in the preparation of semiconductor packaging materials or inductance materials.

[0052] In the field of semiconductor, when assembling passive elements, semiconductor elements, electroacoustic devices, display devices, optical devices, radio frequency devices and the like into devices, circuit board substrates such as high-density interconnection boards, high-frequency high-speed boards and mother boards are required. These substrates are generally mainly composed of fillers and resins and the like organic polymers. The modified metal magnetic powder provided in the present application can effectively meet the heat dissipation requirements of semiconductor packaging materials or substrate materials when applied to the preparation of semiconductor packaging materials or substrate materials.

[0053] Compared with the prior art, the present application has the following technical effects:

[0054] (1) The present application provides a modified metal magnetic powder having a core-shell structure with a metal magnetic powder as the core and a siloxane compound as the shell. The modified metal magnetic powder has a low core loss and a low water absorption after storage. 29 In the Si-NMR nuclear magnetic resonance spectrum, the ratio of the peak integral area of the modified metal magnetic powder of the present application in the range of -80ppm to -120ppm to the range of +20ppm to -120ppm is 50-99.5:100. The modified metal magnetic powder of the present application can be insulated by modifying the surface of the metal magnetic powder with a siloxane compound, thereby reducing the eddy current loss of the magnetic powder core. Further, the modified metal magnetic powder of the present application also has the excellent characteristic of low water absorption after storage, which can reduce the water absorption of the modified metal magnetic powder during the shelf life and reduce the risk of conduction at high frequencies due to high water content.

[0055] (2) The present application uses T-unit siloxane raw material to form a polysiloxane layer on the surface of the 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 ordered arrangement of the organic groups of T-unit siloxane, forming a uniform polysiloxane layer. Finally, through calcination treatment, part of the organic groups of T-unit siloxane are removed to convert them to Q units, and the uniform polysiloxane layer is converted to a dense siloxane compound shell. Thus, the present application provides a metal magnetic powder with a continuous and dense siloxane compound shell, which has low water absorption after storage. DETAILED DESCRIPTION

[0056] The present application will be further described below in conjunction with examples. Those skilled in the art will be able to implement the present application based on these descriptions. In addition, the examples of the present application involved in the following description are generally only a part of the examples of the present application, not all examples. Therefore, based on the examples in the present application, all other examples obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.

[0057] The moisture content of the particles is the moisture at 200 degrees Celsius, measured using a Karl Fischer moisture meter, model CA-310 from Mitsubishi Chemical, using the Coulomb method. In the performance test, the moisture content is measured in ppm / m 2 which is calculated as the measured moisture content divided by the geometric outer surface area of the particles of the test substance (calculated from the measured average particle size).

[0058] The average particle size is measured using a Beckman Coulter laser particle size distribution meter LS-13320, using deionized water as the solvent. In this context, the average particle size refers to the volume average diameter of the particles.

[0059] In the siloxane compound of the present application 29 The total content of groups bonded to Si is represented by the peak integral area in the range of +20 ppm to -120 ppm, and the content of Q units is represented by the peak integral area in the range of -80 ppm to -120 ppm. The modified metal magnetic powder provided in the present application has a 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 50 to 99.5:100.

[0060] The coating thickness of the siloxane compound of the modified metal magnetic powder, i.e., the shell thickness of the modified metal magnetic powder, is measured by high-resolution transmission electron microscopy.

[0061] Example 1

[0062] A modified metal magnetic powder having a continuous, dense siloxane compound shell is provided and is prepared as follows:

[0063] Step S1, methyltrimethoxysilane (MTMS) is added to metal magnetic powder having an average particle size of 0.5 μm, and after 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 to obtain a precursor. The mass ratio of the metal magnetic powder, MTMS, and 5% ammonia water is 50:1:1.

[0064] Step S2, the precursor obtained in Step S1 is placed in a muffle furnace, heated to 70°C, and held at this temperature for 24 hours to dry the precursor to a low moisture content of 0.8%.

[0065] Step S3, nitrogen gas is introduced into the muffle furnace to create a nitrogen atmosphere, and then the temperature is raised to 750°C at a rate of 5°C / min, and held at this temperature for 6 hours to perform calcination to densify the surface of the precursor, and then the furnace is cooled to room temperature to obtain a modified metal magnetic powder having a continuous, dense siloxane compound coating on the surface. The coating thickness of the siloxane compound is 2.0 nm.

[0066] Example 2

[0067] A modified metal magnetic powder having a continuous and dense shell of siloxane compound is provided and prepared by the following method:

[0068] Step S1, methyltrimethoxysilane (MTMS) is added to metal magnetic powder having an average particle size of 0.5 μm, and after 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 to obtain a precursor. The mass ratio of the metal magnetic powder, the MTMS, and the 5% ammonia water by volume is 50:1:1.

[0069] Step S2, the precursor obtained in Step S1 is placed in a muffle furnace, and heated to 70°C for 24 hours to dry the precursor to a low moisture content of 0.2%.

[0070] Step S3, nitrogen is introduced into the muffle furnace to create a nitrogen atmosphere, and then the temperature is raised to 750°C at a rate of 5°C / min, and held for 6 hours to calcine the precursor to densify the surface of the precursor, and then the furnace is cooled to room temperature to obtain a modified metal magnetic powder having a continuous and dense shell of siloxane compound. The thickness of the siloxane compound shell is 2.3 nm.

[0071] Example 3

[0072] A modified metal magnetic powder having a continuous and dense shell of siloxane compound is provided and prepared by the following method:

[0073] Step S1, methyltrimethoxysilane (MTMS) is added to metal magnetic powder having an average particle size of 0.5 μm, and after 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 to obtain a precursor. The mass ratio of the metal magnetic powder, the MTMS, and the 5% ammonia water by volume is 50:1:1.

[0074] Step S2, the precursor obtained in Step S1 is placed in a muffle furnace, and heated to 70°C for 24 hours to dry the precursor to a low moisture content of 1%.

[0075] Step S3, nitrogen is introduced into the muffle furnace to create a nitrogen atmosphere, and then the temperature is raised to 750°C at a rate of 5°C / min, and held for 6 hours to calcine the precursor to densify the surface of the precursor, and then the furnace is cooled to room temperature to obtain a modified metal magnetic powder having a continuous and dense shell of siloxane compound. The thickness of the siloxane compound shell is 2.0 nm.

[0076] Example 4

[0077] A modified metal magnetic powder having a continuous and dense shell of siloxane compound is provided and is prepared by the following method:

[0078] Step S1, methyltrimethoxysilane (MTMS) is added to metal magnetic powder having an average particle size of 1 μm, and after being mixed uniformly, ammonia water having a volume concentration of 5% is added, and reaction is performed at 25°C to form polysiloxane on the surface of the metal magnetic powder to obtain a precursor. The mass ratio of the metal magnetic powder, the MTMS, and the ammonia water having a volume concentration of 5% is 50:1:1.

[0079] Step S2, the precursor obtained in Step S1 is placed into a muffle furnace, and is heated to 70°C for constant temperature for 24 hours to perform drying treatment, so that the precursor is in a low moisture content state having a water content of 0.8%.

[0080] Step S3, nitrogen is introduced into the muffle furnace to make the furnace have a nitrogen atmosphere, and then the temperature is increased to 750°C at a temperature increasing rate of 5°C / min, and is kept for 6 hours to perform calcination treatment to densify the surface of the precursor, and then the furnace is cooled to room temperature to obtain a modified metal magnetic powder having a continuous and dense shell of siloxane compound. The coating thickness of the siloxane compound is 7.0 nm.

[0081] Example 5

[0082] A modified metal magnetic powder having a continuous and dense shell of siloxane compound is provided and is prepared by the following method:

[0083] Step S1, methyltrimethoxysilane (MTMS) is added to metal magnetic powder having an average particle size of 1.8 μm, and after being mixed uniformly, ammonia water having a volume concentration of 5% is added, and reaction is performed at 25°C to form polysiloxane on the surface of the metal magnetic powder to obtain a precursor. The mass ratio of the metal magnetic powder, the MTMS, and the ammonia water having a volume concentration of 5% is 50:1:1.

[0084] Step S2, the precursor obtained in Step S1 is placed into a muffle furnace, and is heated to 70°C for constant temperature for 24 hours to perform drying treatment, so that the precursor is in a low moisture content state having a water content of 0.8%.

[0085] Step S3, nitrogen is introduced into the muffle furnace to make the furnace have a nitrogen atmosphere, and then the temperature is increased to 750°C at a temperature increasing rate of 5°C / min, and is kept for 6 hours to perform calcination treatment to densify the surface of the precursor, and then the furnace is cooled to room temperature to obtain a modified metal magnetic powder having a continuous and dense shell of siloxane compound. The coating thickness of the siloxane compound is 24.0 nm.

[0086] Example 6

[0087] A modified metal magnetic powder having a continuous and dense shell of siloxane compound is provided and is prepared by the following method:

[0088] Step S1, methyltrimethoxysilane (MTMS) is added to metal magnetic powder with an average particle size of 0.05 μm, and then ammonia water with a volume concentration of 5% is added after uniform mixing. The surface of the metal magnetic powder is formed with polysiloxane by reaction at 25°C to obtain a precursor. The mass ratio of the metal magnetic powder, MTMS, and ammonia water with a volume concentration of 5% is 50:1:1.

[0089] Step S2, the precursor obtained in Step S1 is placed into a muffle furnace, and dried by heating to 70°C for 24 hours to make the precursor in a low moisture content state with a water content of 0.8%.

[0090] Step S3, nitrogen is introduced into the muffle furnace to make the furnace in a nitrogen atmosphere, and then the temperature is raised to 750°C at a temperature raising rate of 5°C / min and kept for 6 hours for calcination treatment to densify the surface of the precursor. Then the furnace is cooled to room temperature to obtain modified metal magnetic powder with a continuous and dense siloxane compound shell on the surface. The thickness of the siloxane compound shell is 0.5 nm.

[0091] Example 7

[0092] A modified metal magnetic powder with a continuous and dense siloxane compound shell is provided, which is prepared by the following method:

[0093] Step S1, methyltrimethoxysilane (MTMS) is added to 40 μm metal magnetic powder, and then ammonia water with a volume concentration of 5% is added after uniform mixing. The surface of the metal magnetic powder is formed with polysiloxane by reaction at 25°C to obtain a precursor. The mass ratio of the metal magnetic powder, MTMS, and ammonia water with a volume concentration of 5% is 50:1:1.

[0094] Step S2, the precursor obtained in Step S1 is placed into a muffle furnace, and dried by heating to 70°C for 24 hours to make the precursor in a low moisture content state with a water content of 0.8%.

[0095] Step S3, nitrogen is introduced into the muffle furnace to make the furnace in a nitrogen atmosphere, and then the temperature is raised to 750°C at a temperature raising rate of 5°C / min and kept for 6 hours for calcination treatment to densify the surface of the precursor. Then the furnace is cooled to room temperature to obtain modified metal magnetic powder with a continuous and dense siloxane compound shell on the surface. The thickness of the siloxane compound shell is 260.1 nm.

[0096] Example 8

[0097] A modified metal magnetic powder with a continuous and dense siloxane compound shell is provided, which is prepared by the following method:

[0098] Step S1, methyltrimethoxysilane (MTMS) is added to metal magnetic powder with an average particle size of 40 μm, and then ammonia water with a volume concentration of 5% is added after uniform mixing, and polysiloxane is formed on the surface of the metal magnetic powder by reaction at 25°C to obtain a precursor. The mass ratio of the metal magnetic powder, the MTMS, and the ammonia water with a volume concentration of 5% is 45:1:1.

[0099] Step S2, the precursor obtained in step S1 is placed into a muffle furnace, and dried at 70°C for 24 hours to make the precursor in a low moisture content state with a water content of 0.8%.

[0100] Step S3, nitrogen is introduced into the muffle furnace to make the furnace in a nitrogen atmosphere, and then the temperature is raised to 750°C at a temperature raising rate of 5°C / min and kept for 6 hours for calcination treatment to densify the surface of the precursor, and then the furnace is cooled to room temperature to obtain modified metal magnetic powder with a continuous and dense siloxane compound shell. The coating thickness of the siloxane compound is 300.0 nm.

[0101] Example 9

[0102] A modified metal magnetic powder with a continuous and dense siloxane compound shell is provided, which is prepared by the following method:

[0103] Step S1, methyltrimethoxysilane (MTMS) is added to metal magnetic powder with an average particle size of 10 μm, and then ammonia water with a volume concentration of 5% and nano-silicon dioxide powder are added after uniform mixing, and polysiloxane is formed on the surface of the metal magnetic powder by reaction at 25°C to obtain a precursor. The mass ratio of the metal magnetic powder, the MTMS, the ammonia water with a volume concentration of 5%, and the nano-silicon dioxide powder is 50:3:3:0.01. The average particle size of the nano-silicon dioxide powder is 30 nm.

[0104] Step S2, the precursor obtained in step S1 is placed into a muffle furnace, and dried at 70°C for 24 hours to make the precursor in a low moisture content state with a water content of 0.8%.

[0105] Step S3, nitrogen is introduced into the muffle furnace to make the furnace in a nitrogen atmosphere, and then the temperature is raised to 650°C at a temperature raising rate of 5°C / min and kept for 6 hours for calcination treatment to densify the surface of the precursor, and then the furnace is cooled to room temperature to obtain modified metal magnetic powder with a continuous and dense siloxane compound shell. The coating thickness of the siloxane compound is 127.1 nm.

[0106] Example 10

[0107] A modified metal magnetic powder with a continuous and dense siloxane compound shell is provided, which is prepared by the following method:

[0108] Step S1, methyltrimethoxysilane (MTMS) is added to metal magnetic powder with an average particle size of 10 μm, and then ammonia water with a volume concentration of 5% and nano-silica powder are added after uniform mixing. Reaction is carried out at 25°C to form polysiloxane on the surface of the metal magnetic powder to obtain a precursor. The mass ratio of the 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.

[0109] Step S2, the precursor obtained in step S1 is placed into a muffle furnace and heated to 70°C for constant temperature for 24 hours for drying treatment, so that the precursor is in a low moisture content state with a water content of 0.8%.

[0110] Step S3, nitrogen is introduced into the muffle furnace to make the furnace in a nitrogen atmosphere, and then the temperature is raised to 650°C at a temperature raising rate of 5°C / min for heat preservation for 6 hours for calcination treatment to densify the surface of the precursor. Then the furnace is cooled to room temperature to obtain modified metal magnetic powder with a continuous and dense siloxane compound shell on the surface. The coating thickness of the siloxane compound is 118.0 nm.

[0111] Example 11

[0112] A modified metal magnetic powder with a continuous and dense siloxane compound shell is provided, which is prepared by the following method:

[0113] Step S1, methyltrimethoxysilane (MTMS) is added to metal magnetic powder with an average particle size of 10 μm, and then ammonia water with a volume concentration of 5% and nano-silica powder are added after uniform mixing. Reaction is carried out at 25°C to form polysiloxane on the surface of the metal magnetic powder to obtain a precursor. The mass ratio of the 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.

[0114] Step S2, the precursor obtained in step S1 is placed into a muffle furnace and heated to 70°C for constant temperature for 24 hours for drying treatment, so that the precursor is in a low moisture content state with a water content of 0.8%.

[0115] Step S3, nitrogen is introduced into the muffle furnace to make the furnace in a nitrogen atmosphere, and then the temperature is raised to 650°C at a temperature raising rate of 5°C / min for heat preservation for 6 hours for calcination treatment to densify the surface of the precursor. Then the furnace is cooled to room temperature to obtain modified metal magnetic powder with a continuous and dense siloxane compound shell on the surface. The coating thickness of the siloxane compound is 135.6 nm.

[0116] Example 12

[0117] A modified metal magnetic powder having a continuous and dense shell of siloxane compound is provided and is prepared by the following method:

[0118] In step S1, methyltrimethoxysilane (MTMS) is added to metal magnetic powder having an average particle size of 10 μm, and after mixing, 5% ammonia water and nano-silica powder are added. The mixture is reacted at 25°C to form polysiloxane on the surface of the metal magnetic powder to obtain a precursor. The mass ratio of the metal magnetic powder, MTMS, 5% ammonia water, and nano-silica powder is 50:3:3:0.01. The average particle size of the nano-silica powder is 7 nm.

[0119] In step S2, the precursor obtained in step S1 is placed in a muffle furnace and dried at 70°C for 24 hours to reduce the moisture content of the precursor to 0.8%.

[0120] In step S3, nitrogen is introduced into the muffle furnace to create a nitrogen atmosphere, and the temperature is then increased to 650°C at a rate of 5°C / min and held for 6 hours to calcine the precursor and densify the surface of the precursor. The furnace is then cooled to room temperature to obtain a modified metal magnetic powder having a continuous and dense shell of siloxane compound. The thickness of the siloxane compound shell is 109.9 nm.

[0121] Example 13

[0122] A modified metal magnetic powder having a continuous and dense shell of siloxane compound is provided and is prepared by the following method:

[0123] In step S1, methyltrimethoxysilane (MTMS) is added to metal magnetic powder having an average particle size of 10 μm, and after mixing, 5% ammonia water and nano-silica powder are added. The mixture is reacted at 25°C to form polysiloxane on the surface of the metal magnetic powder to obtain a precursor. The mass ratio of the metal magnetic powder, MTMS, 5% ammonia water, and nano-silica powder is 50:3:3:0.01. The average particle size of the nano-silica powder is 120 nm.

[0124] In step S2, the precursor obtained in step S1 is placed in a muffle furnace and dried at 70°C for 24 hours to reduce the moisture content of the precursor to 0.8%.

[0125] In step S3, nitrogen is introduced into the muffle furnace to create a nitrogen atmosphere, and the temperature is then increased to 650°C at a rate of 5°C / min and held for 6 hours to calcine the precursor and densify the surface of the precursor. The furnace is then cooled to room temperature to obtain a modified metal magnetic powder having a continuous and dense shell of siloxane compound. The thickness of the siloxane compound shell is 137.7 nm.

[0126] Example 14

[0127] A modified metal magnetic powder having a continuous and dense shell of siloxane compound is provided and is prepared by the following method:

[0128] Step S1, methyltrimethoxysilane (MTMS) is added to metal magnetic powder having an average particle size of 10 μm, and after mixing uniformly, ammonia water having a volume concentration of 5% and nano-silica powder are added, and reaction is performed at 25°C to form polysiloxane on the surface of the metal magnetic powder to obtain a precursor. The mass ratio of the metal magnetic powder, the MTMS, the ammonia water having a volume concentration of 5%, and the nano-silica powder is 50:3:3:0.019. The average particle size of the nano-silica powder is 30 nm.

[0129] Step S2, the precursor obtained in Step S1 is placed in a muffle furnace, heated to 50°C for 10 hours, and dried to have a low moisture content of 0.8%.

[0130] Step S3, nitrogen is introduced into the muffle furnace to make the furnace have a nitrogen atmosphere, and then the temperature is raised to 1000°C at a rate of 5°C / min and held for 10 hours to perform calcination to densify the surface of the precursor, and then the furnace is cooled to room temperature to obtain a modified metal magnetic powder having a continuous and dense shell of siloxane compound. The thickness of the siloxane compound shell is 125.5 nm.

[0131] Example 15

[0132] A modified metal magnetic powder having a continuous and dense shell of siloxane compound is provided and is prepared by the following method:

[0133] Step S1, methyltrimethoxysilane (MTMS) is added to metal magnetic powder having an average particle size of 10 μm, and after mixing uniformly, ammonia water having a volume concentration of 5% and nano-silica powder are added, and reaction is performed at 25°C to form polysiloxane on the surface of the metal magnetic powder to obtain a precursor. The mass ratio of the metal magnetic powder, the MTMS, the ammonia water having a volume concentration of 5%, and the nano-silica powder is 50:3:3:0.019. The average particle size of the nano-silica powder is 30 nm.

[0134] Step S2, the precursor obtained in Step S1 is placed in a muffle furnace, heated to 200°C for 6 hours, and dried to have a low moisture content of 0.8%.

[0135] Step S3, nitrogen is introduced into the muffle furnace to make the furnace have a nitrogen atmosphere, then the temperature is raised to 1200℃ at a rate of 5℃ / min, and the precursor is calcined for 24h to make the surface of the precursor densified, then the furnace is cooled to room temperature, and a modified metal magnetic powder with a continuous and dense siloxane compound coating on the surface is obtained. The coating thickness of the siloxane compound is 115.6nm.

[0136] Comparative Example 1

[0137] The main difference from Example 1 is that the average particle size of the metal magnetic powder in Step S1 is 0.02μm. The others are the same as Example 1.

[0138] The coating thickness of the siloxane compound in this comparative example is 1.2nm.

[0139] Comparative Example 2

[0140] The main difference from Example 1 is that the average particle size of the metal magnetic powder in Step S1 is 46μm. The others are the same as Example 1.

[0141] The coating thickness of the siloxane compound in this comparative example is 320.2nm.

[0142] Comparative Example 3

[0143] The main difference from Example 1 is that the average particle size of the metal magnetic powder in Step S1 is 46μm; in Step S1, the mass ratio of the metal magnetic powder, MTMS, and ammonia water with a volume concentration of 5% is 40:1:1. The others are the same as Example 1.

[0144] The coating thickness of the siloxane compound in this comparative example is 450.4nm.

[0145] Comparative Example 4

[0146] The main difference from Example 1 is that the water content of the precursor in Step S2 is 0.01%. The others are the same as Example 1.

[0147] The coating thickness of the siloxane compound in this comparative example is 2.4nm.

[0148] Comparative Example 5

[0149] The main difference from Example 1 is that the water content of the precursor in Step S2 is 1.2%. The others are the same as Example 1.

[0150] The coating thickness of the siloxane compound in this comparative example is 2.1nm.

[0151] Comparative Example 6

[0152] The main difference from Example 1 is that the gas atmosphere for calcination in step S3 is air. Other than that, it is the same as Example 1.

[0153] The coating thickness of the siloxane compound was measured to be 2.3 nm.

[0154] Comparative Example 7

[0155] The main difference from Example 1 is that the temperature for calcination in step S3 is 600°C, and the holding time is 5 h. Other than that, it is the same as Example 1.

[0156] The coating thickness of the siloxane compound was measured to be 2.2 nm.

[0157] Comparative Example 8

[0158] The main difference from Example 1 is that the temperature for calcination in step S3 is 550°C, and the holding time is 6 h. Other than that, it is the same as Example 1.

[0159] The coating thickness of the siloxane compound was measured to be 2.3 nm.

[0160] Performance Characterization

[0161] The modified metal magnetic powders prepared in Examples 1-15 and Comparative Examples 1-8 were tested for particle size, Q unit content, and water content after storage. The results are shown in Table 1. The water content after storage was tested by storing the modified metal magnetic powders in an open container at 25°C and 50% RH for 48 hours. The Q unit content was the solid content of the modified metal magnetic powders, as measured by the method described in the Test Methods section. 29 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 in the Si-NMR nuclear magnetic resonance spectrum.

[0162] Table 1

[0163]

[0164] From Table 1, it can be seen that:

[0165] (1) From Examples 1-15, it can be seen that, by using T-unit siloxane raw material, the present application forms a polysiloxane layer on the surface of the metal magnetic powder; then, by drying treatment, the polysiloxane layer is in a state of low moisture content, promoting the condensation of silanol groups, and the organic groups of T-unit siloxane are orderly arranged, forming a uniform polysiloxane layer, which is conducive to the formation of dense siloxane compounds; finally, by calcination treatment, part 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 property of having less water content after storage. Since the modified metal magnetic powder is applied to semiconductor fillers, it has a dense siloxane compound shell layer, which can reduce the water absorption of the metal magnetic powder during the shelf life, reduce the eddy current loss of the magnetic powder core during the operation of electronic devices, and reduce the risk of easy conduction between magnetic powder particles caused by high water content.

[0166] (2) In the preparation method of the modified metal magnetic powder of the present application, the selection conditions of particle size are analyzed as follows:

[0167] From the comparative analysis of Comparative Examples 1-2 and Example 1, it can be seen that the particle sizes of the metal magnetic powders of Comparative Examples 1-2 are 0.02 μm and 46 μm, respectively, and their water contents are 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 T-unit siloxane is difficult to uniformly adsorb on the surface of the metal magnetic powder, so it is difficult to form a uniform polysiloxane film layer thereon, thereby resulting in poor coating effect. Since the thickness of the siloxane compound to be coated is small, and 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 uniformly adsorb on the surface of the metal magnetic powder, resulting in uneven coating. Uneven coating will lead to increased water absorption of the product after storage. Therefore, the particle size of the metal magnetic powder prepared by the method of the present application needs to be controlled within a suitable range.

[0168] Further, from the comparative analysis of the water content characterization data of Example 1, Examples 6-7, and Comparative Examples 1-2, it can be seen that the particle size of the metal magnetic powder of the present application is preferably 0.05-40 μm.

[0169] And from the comparative analysis of Example 8 and Example 7, Example 1, it can be seen that the particle size of the metal magnetic powder of Example 7 is larger than that of Example 1. In order to improve the coating amount of Example 7 to improve the uniformity of the coating film layer and to improve the film density, the amount of T units of siloxane added can be increased, such as Example 8, which improves the amount of siloxane added, and the coating uniformity is better than that of Example 7 (reflected in the lower water absorption of Example 8). But by comparing Comparative Example 3 with Comparative Example 2, when the particle size of the metal magnetic powder of Comparative Example 2 increases to 46 μm, although Comparative Example 3 increases the amount of siloxane added, the water absorption of Comparative Example 3 is more than that of Comparative Example 2, and during the preparation process, it is found that the metal magnetic powder has agglomeration phenomenon. Therefore, it is speculated that too much T units of siloxane will increase the viscosity of the metal magnetic powder, and the siloxane cannot be uniformly adsorbed on the surface of the metal magnetic powder to form a polysiloxane film layer, which ultimately leads to a decrease in the density of the siloxane compound film layer obtained by calcination. Therefore, it is further speculated that in order to form a uniform and dense siloxane compound shell layer and to reduce the water content of the product, the particle size of the metal magnetic powder needs to be controlled within a certain range.

[0170] (3) In the preparation method of the modified metal magnetic powder of the present application, the analysis of the water content of the precursor:

[0171] From the comparative analysis of Comparative Examples 4-5 and Example 1, it can be seen that the water content of the precursor after drying of Comparative Examples 4 and 5 is 0.01% and 1.2%, respectively, and the water content of the modified metal magnetic powder product obtained after storage is greatly increased compared with Example 1. Therefore, it can be seen that the water content of the precursor is within a certain range, which is beneficial to the formation of a dense siloxane compound. The water content of the precursor is preferably in a low moisture content state of 0.1% to 1%. The reason for this is that the polysiloxane layer is in a state of 0.1% to 1% low moisture content, which can promote the rotation of the organic group of T units of siloxane and orderly arrange it, so as to form a uniform polysiloxane layer, and further make the obtained siloxane compound shell layer more dense and have lower porosity.

[0172] (4) In the preparation method of the modified metal magnetic powder of the present application, the analysis of the conditions of the calcination gas atmosphere of the precursor:

[0173] From the comparative analysis of Comparative Example 6 and Example 1, it can be seen that the gas atmosphere of the calcination treatment in step S3 of Comparative Example 6 is air, and the water content of the product of Comparative Example 6 greatly increases after being placed. The reason is that in the air, it contains active gas oxygen, which will react with the carbon formed by the decomposition of the organic group, and after taking away the carbon, defects will be formed at the carbon sites, so the porosity is high, the shell layer is not dense, and the product has a large water absorption. When calcination is carried out in an inert atmosphere, although the water discharged by the condensation of silicon hydroxyl groups will also react with carbon to take away carbon, the water content is low, so the rate of taking away carbon is slow, and the continuous condensation of silicon hydroxyl groups in the film layer can repair the defect sites, so the porosity is low, and finally the water content of the product is low.

[0174] (5) In the preparation method of the modified metal magnetic powder of the present application, the condition analysis of the unit content of the product Q:

[0175] From the comparative analysis of Comparative Examples 7-8 and Example 1, it can be seen that by adjusting the temperature and time of the calcination step, Comparative Examples 7 and 8 reduce the transformation of T units to Q units, so that the Q unit content of the products of Comparative Examples 7 and 8 is 47.0% and 42.1% respectively, and the water content of the modified metal magnetic powder obtained by them is 195.4 ppm / m 2 , 274.6 ppm / m 2 , respectively, which greatly increases. Therefore, it can be seen that the modified metal magnetic powder provided by the present application controls the content of Q units within a certain range, so that the water content of the obtained modified metal magnetic powder is low after being placed.

[0176] (6) In the preparation method of the modified metal magnetic powder of the present application, the condition analysis of the addition of nano-silicon dioxide in the preparation process: From the comparative analysis of Examples 9-11 and Example 1, it can be seen that different particle sizes and contents of nano-silicon dioxide are added in the preparation process of Examples 9-11, and the water content after being placed has different degrees of reduction, which shows that the addition of nano-silicon dioxide can improve the density of the siloxane compound film layer prepared. The reason is that when the siloxane is condensed to form polysiloxane, it is not dense, and a small amount of silicon dioxide powder is added in the reaction process and dispersed in the polysiloxane skeleton. In step S3, the calcination removes the organic group of polysiloxane, and these silicon dioxide powders can well fill the position of the organic group, improving the density of the siloxane compound shell layer on the surface of the metal magnetic powder. Further, from the comparison of Examples 9-11 and Examples 12-13, it can be seen that the particle size of the nano-silicon dioxide powder should be 10-100 nm, otherwise it cannot play the role of filling in the polysiloxane skeleton. For example, Example 12 cannot play a role, and the water content has no reduction compared with Example 1. In Example 13, the particle size of the added silicon dioxide is too large, which will destroy the continuity of the shell layer, and finally result in a large water content.

[0177] The raw material metal magnetic powder used in the examples of the present application is purchased from Shenzhen Ptco New Material Co., Ltd.

[0178] The raw materials and equipment used in the present application are common raw materials and equipment in the art, unless otherwise specified; the methods used in the present application are conventional methods in the art, unless otherwise specified.

[0179] The above is only the preferred embodiment of the present application, and does not limit the present application in any way. Any simple modification, change and equivalent transformation of the above embodiment based on the technical essence of the present application still falls within the protection scope of the technical solution of the present application.

Claims

1. A modified metal magnetic powder, characterized by: The modified metal magnetic powder has a core-shell structure with a metal magnetic powder as a core and a siloxane compound as a shell layer; the siloxane compound is prepared by polymerization of a T unit siloxane as a raw material and calcination treatment, wherein the T unit = R1SiO3-, and R1 is a hydrogen atom or an independently selected hydrocarbon group of 1 to 16 carbon atoms; In the solid state 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 -80 ppm to -120 ppm to the peak integral area in the range of +20 ppm to -120 ppm is 50.0~99.5:

100.

2. The modified metal magnetic powder of claim 1, wherein: The modified metal magnetic powder has a Karl Fischer moisture at 200°C of not more than 150 ppm / m after being left in an environment of 25°C, 50% RH for 48 hours. 2 .

3. The modified metal magnetic powder of claim 1 wherein: The T unit siloxane is selected from a hydrocarbon group trialkoxysilane and a hydrocarbon group trichlorosilane.

4. The modified metal magnetic powder of claim 1 wherein: The thickness of the shell layer is 0.5 nm to 300 nm.

5. The method of producing a modified metal magnetic powder according to any one of claims 1 to 4, wherein: The method comprises the following steps: Step S1, adding a T unit siloxane to the metal magnetic powder to perform a reaction to form a polysiloxane on the surface of the metal magnetic powder to obtain a precursor; Step S2, performing a drying treatment to place the precursor in a low moisture content state; Step S3, performing a calcination treatment to densify the surface of the precursor to obtain the modified metal magnetic powder; The T unit = R1SiO3-, and R1 is a hydrogen atom or an independently selected hydrocarbon group of 1 to 16 carbon atoms, and the modified metal magnetic powder has a dense siloxane compound shell layer.

6. The method for preparing modified metal magnetic powder as described in claim 5, characterized in that: In step S1, an alkaline aqueous solution is added to perform the reaction.

7. The method for preparing modified metal magnetic powder as described in claim 6, characterized in that: Silicon dioxide powder is also added to perform the reaction.

8. The method for preparing modified metal magnetic powder as described in claim 7, characterized in that: The particle size of the silicon dioxide powder is 10 nm to 100 nm.

9. The method for preparing modified metal magnetic powder as described in claim 5, characterized in that: In step S1, the particle size of the metal magnetic powder is 0.05 μm to 40 μm.

10. The method for preparing modified metal magnetic powder as described in claim 5, characterized in that: In step S2, the drying treatment is performed to make the water content of the precursor 0.1% to 1%.

11. The method of producing a modified metal magnetic powder according to claim 5 or 10, wherein: The drying treatment method is to heat to 50°C to 200°C and dry for 6 hours to 24 hours.

12. The method for preparing modified metal magnetic powder as described in claim 5, characterized in that: In step S3, the calcination treatment is performed in an inert gas atmosphere.

13. The method for preparing modified metal magnetic powder as described in claim 5, characterized in that: In step S3, the temperature of the calcination treatment is 600°C to 1200°C.

14. The method for preparing modified metal magnetic powder as described in claim 13, characterized in that: In step S3, the time of the calcination treatment is 6 hours to 72 hours.

15. Use of the modified metal magnetic powder according to any one of claims 1 to 4 or prepared by the preparation method according to any one of claims 5 to 14 in preparation of a semiconductor packaging material or an inductor material.

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