Spherical silica powder and preparation method thereof

Abstract

According to the spherical silica powder and the preparation method thereof provided by the invention, through compounding of the surface modified spherical silica powder and the sulfydryl silane coupling agent modified silicon dioxide nanoparticles, the two kinds of spherical silica powder with different particle sizes are mutually coupled, so that the flowability of an epoxy molding compound is improved, and the packaging molding performance is improved; meanwhile, an imidazole group is introduced to the surface of the spherical silica powder through surface modification, sulfydryl is introduced to the surfaces of the silica nanoparticles, the dispersion uniformity and interfacial compatibility of the spherical silica powder in the epoxy molding compound are improved, the sulfydryl can be subjected to a curing reaction with an epoxy group on epoxy resin, the filling effect of the silica powder is improved, and the filling effect of the silica powder is improved. And the comprehensive properties of high heat conductivity, high temperature welding resistance, high moisture resistance, high bonding strength, low stress, low expansion, low water absorption and the like of the packaging material are improved.

Description

Technical Field

[0001] The invention relates to the field of silicon micropowder materials, and in particular to a method for preparing spherical silicon micropowder. Background Art

[0002] Spherical silica powder is an amorphous quartz powder material whose main component is SiO2. It has the advantages of fine particles, high purity, excellent dielectric properties, high thermal conductivity, and low thermal expansion coefficient. It is widely used in electronics, rubber industry, coatings, aerospace and other fields.

[0003] Integrated circuit packaging is one of the most important and widely used applications of spherical silicon powder. It can effectively improve the thermal stability, mechanical strength, electrical insulation, thermal expansion coefficient, internal stress and modulus of packaging materials, and the filling rate can reach 70%~90%. The higher the filling rate of silicon powder, the smaller its thermal expansion coefficient, the lower its thermal conductivity, the closer it is to the thermal expansion coefficient of single crystal silicon, and the better the performance of the electronic components produced thereby. However, the compatibility of spherical silicon powder with epoxy molding compound matrix resin is poor. The increase in filling amount will further lead to the deterioration of the dispersion uniformity and compatibility of spherical silicon powder in epoxy molding compound, and will also greatly reduce the fluidity of epoxy molding compound, which is not conducive to the packaging molding process, resulting in poor comprehensive performance of packaging materials, and cannot meet the requirements of large-scale and ultra-large-scale integrated circuits for packaging materials of high purity, high reliability, high thermal conductivity, high temperature welding resistance, high moisture resistance, high bonding strength, low stress, low expansion, low water absorption, low viscosity, low environmental pollution, and easy processing. Summary of the invention

[0004] In order to overcome the above-mentioned defects, the purpose of the present invention is to provide a spherical silicon micropowder and a preparation method thereof. By compounding surface-modified spherical silicon micropowder and mercaptosilane coupling agent-modified silicon dioxide nanoparticles, two spherical silicon micropowders with different particle sizes are coupled with each other, the fluidity of epoxy molding plastics is improved, and the packaging molding performance is improved; at the same time, imidazole groups are introduced on the surface of the spherical silicon micropowder and mercapto groups are introduced on the surface of the silicon dioxide nanoparticles through surface modification, so as to improve the dispersion uniformity and interface compatibility of the spherical silicon micropowder in the epoxy molding plastics, and the mercapto groups can also undergo a curing reaction with the epoxy groups on the epoxy resin, so as to improve the filling effect of the silicon micropowder and improve the comprehensive properties of the packaging material such as high thermal conductivity, high temperature welding resistance, high moisture resistance, high bonding strength, low stress, low expansion, and low water absorption.

[0005] The objective of the present invention is achieved through the following technical scheme: a spherical silicon micropowder, comprising surface-modified spherical silicon micropowder and mercaptosilane coupling agent-modified silicon dioxide nanoparticles in a mass ratio of 1:2.5-4, the particle size of the surface-modified spherical silicon micropowder is 5-35 μm, and the particle size of the mercaptosilane coupling agent-modified silicon dioxide nanoparticles is 50-350 nm.

[0006] Preferably, the preparation method of surface-modified spherical silicon micropowder comprises: adding spherical silicon micropowder to a hydrochloric acid solution, stirring, then adding a 30% hydrogen peroxide solution with a mass concentration of 1.0% of the solution volume, continuing stirring overnight, filtering out the precipitate and washing with deionized water until neutral to obtain pretreated spherical silicon micropowder; then dispersing the pretreated spherical silicon micropowder in a 2-5g / L chlorosilane coupling agent solution, stirring and reacting at room temperature for 12-24h, separating the precipitated product and washing it with toluene and anhydrous ethanol in turn, and drying to obtain spherical silicon micropowder modified with a chlorosilane coupling agent; dissolving the spherical silicon micropowder modified with a chlorosilane coupling agent and hydroxyethylimidazole in acetone, dropping a catalyst potassium fluoride, adjusting the pH value of the reaction system to 6-7, reacting at a constant temperature for 12h, removing HCl, and obtaining surface-modified spherical silicon micropowder.

[0007] Preferably, the chlorine-containing silane coupling agent can be one or more of KH-550, KH-431, KH-230, and YDH-702.

[0008] Preferably, the mass ratio of the spherical silica powder modified by the chlorine-containing silane coupling agent to hydroxyethylimidazole is 5-35:1.

[0009] Preferably, the preparation method of mercaptosilane coupling agent modified silica nanoparticles comprises: respectively preparing a tetraethyl orthosilicate solution (the volume ratio of tetraethyl orthosilicate to anhydrous ethanol is 1:2.5) and an ammonia ethanol solution (the volume ratio of a commercially available 25% ammonia solution to anhydrous ethanol is 1:15), and under stirring, dropping the tetraethyl orthosilicate solution into the ammonia ethanol solution at a mixing volume ratio of 1:10-15, and continuing to stir and react for 1-2 hours after the dropwise addition is completed, centrifuging at a low speed of 2500rpm for 5-15 minutes to remove the precipitate, and centrifuging at a high speed of 13000rpm for 15 minutes to separate the precipitate and wash it with anhydrous ethanol and deionized water in turn, and drying to obtain silica nanoparticles; then dispersing the silica nanoparticles in a 2-5g / L mercaptosilane coupling agent solution, stirring and reacting at room temperature for 12-24 hours, separating the precipitate product and washing it with toluene and anhydrous ethanol in turn, and drying to obtain mercaptosilane coupling agent modified silica nanoparticles.

[0010] Preferably, the mercaptosilane coupling agent can be one or more of KH-580 and KH-590.

[0011] The present invention also provides a method for preparing spherical silicon micropowder, comprising mixing surface-modified spherical silicon micropowder and mercaptosilane coupling agent-modified silicon dioxide nanoparticles at a mass ratio of 1:2.5-4 and stirring them uniformly, wherein the particle size of the surface-modified spherical silicon micropowder is 5-35 μm, and the particle size of the mercaptosilane coupling agent-modified silicon dioxide nanoparticles is 50-350 nm.

[0012] The present invention also provides a packaging material, comprising 30-50 parts by mass of epoxy resin, 5-20 parts by mass of curing agent, 0.5-10 parts by mass of curing accelerator, 10-50 parts by mass of spherical silicon powder, 5-15 parts by mass of toughening agent, 1-5 parts by mass of release agent and 0.2-2 parts by mass of colorant.

[0013] Preferably, the epoxy resin may be one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, and o-cresol epoxy resin.

[0014] Preferably, the curing agent can be selected from one or more of dicyandiamide, aromatic amine, melamine and phenolic resin.

[0015] Preferably, the curing agent accelerator can be selected from one or more of organic acid hydrazide and imidazole.

[0016] Preferably, the toughening agent may be one or more of liquid nitrile rubber and liquid silicone rubber.

[0017] The present invention also provides a method for preparing a packaging material, comprising the following steps: Step S1: weigh 30-50 parts by mass of epoxy resin, 5-20 parts by mass of curing agent, 0.5-10 parts by mass of curing accelerator, 10-50 parts by mass of spherical silicon powder, 5-15 parts by mass of toughening agent, 1-5 parts by mass of release agent and 0.2-2 parts by mass of colorant.

[0018] Step S2: In a high-speed mixer, first add the spherical silicon powder prepared in the preparation example, a curing agent and a curing accelerator and mix for 3 minutes, then add other components and mix for 5 minutes.

[0019] Step S3: adding the mixed material in step 2 to a twin-screw extruder, setting the temperature of each section of the extruder to 90°C-120°C, melt-extrude for 3-5 minutes, cool, crush, sieve, and cure by molding on a flat vulcanizer at a curing temperature of 140°C-175°C to obtain an epoxy resin composition.

[0020] Beneficial effects: 1. Surface-modified micron-sized spherical silicon powder and mercaptosilane coupling agent-modified silicon dioxide nanoparticles are mixed to form spherical silicon powder. The two spherical silicon powders with different particle sizes are coupled with each other to exert the synergistic enhancement effect of micro-nano particles, thereby better exerting the filling effect of silicon powder, so that the epoxy resin composition packaging material has better comprehensive properties in conductivity, mechanical properties, heat resistance, moisture resistance, low expansion, low water absorption, packaging processing, etc.

[0021] 2. Surface modification of micron-sized spherical silicon powder and spherical nano-silicon powder and then mixing them can inhibit the agglomeration of spherical silicon powder, and can change the spherical silicon powder from hydrophilic to hydrophobic, improve the interfacial compatibility and dispersion uniformity of spherical silicon powder with epoxy resin, curing agent, and curing accelerator, and thus improve the mechanical properties and moisture resistance of epoxy resin composition. On the other hand, the surface modification of spherical silicon powder by chlorosiloxane and hydroxyethyl imidazole introduces imidazole groups that are the same as the imidazole curing accelerator groups, and the surface modification of nano-spherical silicon powder by mercaptosilane coupling agent introduces mercapto groups that can undergo a ring-opening reaction with the epoxy groups in the epoxy resin, so that the silicon powder and the epoxy resin composition are more tightly combined and dispersed more evenly, thereby improving the electrical conductivity and heat resistance of the epoxy resin composition. DETAILED DESCRIPTION

[0022] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] The present invention is further explained below in conjunction with specific implementation modes.

[0024] Preparation Example 1 A spherical silicon powder, the preparation method of which comprises the following steps: Step 1, preparation of surface modified spherical silicon powder: add spherical silicon powder with a particle size of 15 μm to hydrochloric acid solution, stir, then add 1.0% of the solution volume and a 30% mass concentration of hydrogen peroxide solution, continue stirring overnight, filter out the precipitate and wash with deionized water until neutral to obtain pretreated spherical silicon powder; then disperse the pretreated spherical silicon powder in 3g / L chlorosilane coupling agent KH-550 solution, stir at room temperature for 12h and separate the precipitate. The product was precipitated and washed with toluene and anhydrous ethanol in turn, and dried to obtain spherical silicon micropowder modified by chlorosilane coupling agent KH-550; the spherical silicon micropowder modified by chlorosilane coupling agent KH-550 and hydroxyethylimidazole were dissolved in acetone at a mass ratio of 10:1, and the catalyst potassium fluoride was added dropwise, and the pH value of the reaction system was adjusted to 6-7. The reaction was carried out at a constant temperature for 12 hours, and HCl was removed to obtain surface-modified spherical silicon micropowder. The particle size of the surface-modified spherical silicon micropowder was found to be 21 μm.

[0025] Step 2, preparing mercaptosilane coupling agent modified silica nanoparticles: prepare a tetraethyl orthosilicate solution (the volume ratio of tetraethyl orthosilicate to anhydrous ethanol is 1:2.5) and an ammonia ethanol solution (the volume ratio of a commercially available 25% ammonia solution to anhydrous ethanol is 1:15), respectively, and under stirring, add the tetraethyl orthosilicate solution dropwise to the ammonia ethanol solution at a mixing volume ratio of 1:10. After the addition is completed, continue to stir and react for 1.5 hours, centrifuge at 2500 rpm for 15 minutes to remove the precipitate, and centrifuge at 13000 rpm. The mixture was centrifuged at high speed for 15 minutes, and the precipitate was separated and washed with anhydrous ethanol and deionized water in turn, and dried to obtain silica nanoparticles. The particle size was tested to be 126 nm. The silica nanoparticles were then dispersed in a 3 g / L mercaptosilane coupling agent KH-580 solution, and the reaction was stirred at room temperature for 12 hours. The precipitate product was separated and washed with toluene and anhydrous ethanol in turn, and dried to obtain mercaptosilane coupling agent modified silica nanoparticles. The particle size of the mercaptosilane coupling agent modified silica nanoparticles was tested to be 187 nm.

[0026] Step 3: Mix the surface-modified spherical silicon micropowder and the mercaptosilane coupling agent-modified silicon dioxide nanoparticles in a mass ratio of 1:3 and stir evenly.

[0027] Comparative Preparation Example 1 A spherical silicon powder, the preparation method of which comprises the following steps: Step 1, preparation of surface modified spherical silicon powder: add spherical silicon powder with a particle size of 15 μm to hydrochloric acid solution, stir, then add 1.0% of the solution volume and a 30% mass concentration of hydrogen peroxide solution, continue stirring overnight, filter out the precipitate and wash with deionized water until neutral to obtain pretreated spherical silicon powder; then disperse the pretreated spherical silicon powder in 3g / L chlorosilane coupling agent KH-550 solution, stir at room temperature for 12h and separate the precipitate. The product was precipitated and washed with toluene and anhydrous ethanol in turn, and dried to obtain spherical silicon micropowder modified by chlorosilane coupling agent KH-550; the spherical silicon micropowder modified by chlorosilane coupling agent KH-550 and hydroxyethylimidazole were dissolved in acetone at a mass ratio of 10:1, and the catalyst potassium fluoride was added dropwise, and the pH value of the reaction system was adjusted to 6-7. The reaction was carried out at a constant temperature for 12 hours, and HCl was removed to obtain surface-modified spherical silicon micropowder. The particle size of the surface-modified spherical silicon micropowder was found to be 21 μm.

[0028] Comparative Preparation Example 2 A spherical silicon micropowder, the preparation method of which comprises the following steps: preparing mercaptosilane coupling agent modified silicon dioxide nanoparticles: respectively preparing a tetraethyl orthosilicate solution (the volume ratio of tetraethyl orthosilicate to anhydrous ethanol is 1:2.5) and an ammonia ethanol solution (the volume ratio of a commercially available 25% ammonia solution to anhydrous ethanol is 1:15), under stirring, dripping the tetraethyl orthosilicate solution into the ammonia ethanol solution at a mixing volume ratio of 1:10, continuing to stir and react for 1.5 hours after the dripping is completed, performing low-speed centrifugation at 2500 rpm for 15 minutes to remove the precipitate, and then stirring for 1.5 hours. The mixture was centrifuged at 3000 rpm for 15 min, and the precipitate was separated and washed with anhydrous ethanol and deionized water in turn, and dried to obtain silica nanoparticles. The particle size was found to be 126 nm after testing. The silica nanoparticles were then dispersed in a 3 g / L mercaptosilane coupling agent KH-580 solution, and the reaction was stirred at room temperature for 12 h. The precipitate was separated and washed with toluene and anhydrous ethanol in turn, and dried to obtain mercaptosilane coupling agent modified silica nanoparticles. The particle size of the mercaptosilane coupling agent modified silica nanoparticles was found to be 187 nm.

[0029] Comparative Preparation Example 3 A spherical silicon powder, the preparation method of which comprises the following steps: Step 1, preparing mercaptosilane coupling agent modified silica nanoparticles: prepare tetraethyl orthosilicate solution (the volume ratio of tetraethyl orthosilicate and anhydrous ethanol is 1:2.5) and ammonia ethanol solution (the volume ratio of commercially available 25% ammonia solution and anhydrous ethanol is 1:15) respectively, and under stirring, add the tetraethyl orthosilicate solution dropwise to the ammonia ethanol solution at a mixing volume ratio of 1:10. After the addition is completed, continue to stir and react for 1.5 hours, centrifuge at 2500rpm for 15 minutes to remove the precipitate, centrifuge at 13000rpm for 15 minutes, separate the precipitate and wash it with anhydrous ethanol and deionized water in turn, and obtain silica nanoparticles after drying. The particle size is 126nm after testing.

[0030] Step 2: Spherical silicon micropowder (particle size of 15 μm) and mercaptosilane coupling agent-modified silicon dioxide nanoparticles are mixed in a mass ratio of 1:3 and stirred evenly.

[0031] Example 1 A packaging material, the preparation method of which comprises the following steps: Step S1: Weigh 35 parts by mass of o-cresol epoxy resin, 10 parts by mass of melamine, 1 part by mass of 2-methylimidazole, 45 parts by mass of spherical silica powder prepared in Preparation Example 1, 5 parts by mass of liquid nitrile rubber, 2 parts by mass of release agent stearic acid and 0.2 parts by mass of colorant.

[0032] Step S2: In a high-speed mixer, first add the spherical silicon powder prepared in Preparation Example 1, melamine and 2-methylimidazole and mix for 3 minutes, then add other components and mix for 5 minutes.

[0033] Step S3: adding the mixed material in step 2 to a twin-screw extruder, setting the temperature of each section of the extruder to 90°C-120°C, melt-extrude for 3-5 minutes, cool, crush, sieve, and cure by molding on a flat vulcanizer at a curing temperature of 140°C-175°C to obtain an epoxy resin composition.

[0034] Comparative Example 1 A packaging material, the preparation method of which comprises the following steps: Step S1: Weigh 35 parts by mass of o-cresol epoxy resin, 10 parts by mass of melamine, 1 part by mass of 2-methylimidazole, 45 parts by mass of spherical silica powder obtained in Preparation Comparative Preparation Example 1, 5 parts by mass of liquid nitrile rubber, 2 parts by mass of release agent stearic acid and 0.2 parts by mass of colorant.

[0035] Step S2: In a high-speed mixer, first add the spherical silicon powder prepared in Comparative Preparation Example 1, melamine and 2-methylimidazole and mix for 3 minutes, then add other components and mix for 5 minutes.

[0036] Step S3: adding the mixed material in step 2 to a twin-screw extruder, setting the temperature of each section of the extruder to 90°C-120°C, melt-extrude for 3-5 minutes, cool, crush, sieve, and cure by molding on a flat vulcanizer at a curing temperature of 140°C-175°C to obtain an epoxy resin composition.

[0037] Comparative Example 2 A packaging material, the preparation method of which comprises the following steps: Step S1: Weigh 35 parts by mass of o-cresol epoxy resin, 10 parts by mass of melamine, 1 part by mass of 2-methylimidazole, 45 parts by mass of spherical silica powder prepared in Preparation Comparative Preparation Example 2, 5 parts by mass of liquid nitrile rubber, 2 parts by mass of release agent stearic acid and 0.2 parts by mass of colorant.

[0038] Step S2: In a high-speed mixer, first add the spherical silicon powder prepared in Comparative Preparation Example 2, melamine and 2-methylimidazole and mix for 3 minutes, then add other components and mix for 5 minutes.

[0039] Step S3: adding the mixed material in step 2 to a twin-screw extruder, setting the temperature of each section of the extruder to 90°C-120°C, melt-extrude for 3-5 minutes, cool, crush, sieve, and cure by molding on a flat vulcanizer at a curing temperature of 140°C-175°C to obtain an epoxy resin composition.

[0040] Comparative Example 3 A packaging material, the preparation method of which comprises the following steps: Step S1: Weigh 35 parts by mass of o-cresol epoxy resin, 10 parts by mass of melamine, 1 part by mass of 2-methylimidazole, 45 parts by mass of spherical silica powder prepared in Preparation Comparative Preparation Example 3, 5 parts by mass of liquid nitrile rubber, 2 parts by mass of release agent stearic acid and 0.2 parts by mass of colorant.

[0041] Step S2: In a high-speed mixer, first add the spherical silicon powder prepared in Comparative Preparation Example 3, melamine and 2-methylimidazole and mix for 3 minutes, then add other components and mix for 5 minutes.

[0042] Step S3: adding the mixed material in step 2 to a twin-screw extruder, setting the temperature of each section of the extruder to 90°C-100°C, melt-extrude for 3-5 minutes, cool, crush, sieve, and mold-cure on a flat-plate vulcanizer at a curing temperature of 140°C-175°C to obtain an epoxy resin composition.

[0043] Performance Testing The properties of the epoxy resin compositions prepared in Example 1 and Comparative Examples 1-3 were characterized.

[0044] The volume resistivity was tested according to GB / T 1410-2006, the bending performance was tested according to GB / T 9341-2000, the impact performance was tested according to GB / T 1043-1993, the heat deformation temperature was tested according to GB / T 1634-1979, the water absorption was tested according to GB / T 1034-1998, the gelation time was tested according to the electronic industry standard SJ / P11197-1999, and the thermal expansion coefficient was tested by TMAQ400 instrument, the test temperature was 25-300°C, and the heating rate was 5°C / min. The test results are shown in Table 1 below.

[0045] Table 1 Epoxy resin composition

[0046] From the comparison between Example 1 and Comparative Example 1 and Comparative Example 2, it can be seen that Example 1 has higher volume resistivity, bending strength and impact strength, higher heat deformation temperature, lower linear expansion coefficient and water absorption, and higher gelation time. This may be due to the mutual coupling of two spherical silicon micropowders with different particle sizes, which exerts a synergistic enhancement effect of micro-nano particles, thereby better exerting the filling effect of silicon micropowder, so that the epoxy resin composition packaging material has better comprehensive properties in conductivity, mechanical properties, heat resistance, moisture resistance, low expansion, low water absorption, packaging processing, etc.

[0047] From the comparison between Example 1 and Comparative Example 3, it can be seen that Example 1 has higher volume resistivity, bending strength and impact strength, higher heat deformation temperature, lower linear expansion coefficient and water absorption rate. This may be due to the surface modification of spherical silicon micropowder by chlorosiloxane and hydroxyethyl imidazole, and the surface modification of nano spherical silicon micropowder by mercaptosilane coupling agent, which on the one hand changes the spherical silicon micropowder from hydrophilic to hydrophobic, and similar groups have better compatibility, improves the interface compatibility and dispersion uniformity of spherical silicon micropowder with epoxy resin, curing agent and curing accelerator, and thus improves the epoxy resin. The mechanical properties and moisture resistance of the resin composition. On the other hand, the surface modification of micron-sized spherical silicon powder and nano-sized spherical silicon powder are respectively carried out and then mixed, which can inhibit the agglomeration of the spherical silicon powder. The imidazole group introduced by the surface modification of the spherical silicon powder by chlorosiloxane and hydroxyethyl imidazole is the same as the imidazole curing accelerator group. The mercapto silane coupling agent is used to modify the nano-spherical silicon powder and introduces a mercapto group, which can undergo a ring-opening reaction with the epoxy group in the epoxy resin, so that the silicon powder and the epoxy resin composition are more tightly combined and dispersed more evenly, thereby improving the conductivity and heat resistance of the epoxy resin composition.

[0048] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A spherical silicon powder, characterized in that: The invention comprises surface-modified spherical silicon micropowder and mercaptosilane coupling agent modified silicon dioxide nanoparticles in a mass ratio of 1:2.5-4, wherein the particle size of the surface-modified spherical silicon micropowder is 5-35 μm, and the particle size of the mercaptosilane coupling agent modified silicon dioxide nanoparticles is 50-350 nm. The preparation method of the surface-modified spherical silicon micropowder is as follows: adding the spherical silicon micropowder to a hydrochloric acid solution, stirring, then adding a hydrogen peroxide solution, continuing to stir overnight, filtering out the precipitate and washing with deionized water until neutral. The pretreated spherical silicon micropowder is obtained; the pretreated spherical silicon micropowder is then dispersed in a 2-5g / L chlorosilane coupling agent solution, stirred for reaction at room temperature for 12-24h, separated, washed, and dried to obtain chlorosilane coupling agent-modified spherical silicon micropowder; the chlorosilane coupling agent-modified spherical silicon micropowder and hydroxyethylimidazole are dissolved in acetone, potassium fluoride as a catalyst is added dropwise, the pH value of the reaction system is adjusted to 6-7, and the reaction is carried out at a constant temperature for 12-24h to obtain surface-modified spherical silicon micropowder.

2. The spherical silicon powder according to claim 1, characterized in that: The chlorine-containing silane coupling agent is selected from one or more of KH-550, KH-431, KH-230 and YDH-702.

3. The spherical silicon powder according to claim 1, characterized in that: The mass ratio of the spherical silicon micropowder modified by the chlorine-containing silane coupling agent to hydroxyethylimidazole is 5-35:

1.

4. The spherical silicon powder according to claim 1, characterized in that: The preparation method of silicon dioxide nanoparticles modified by a mercaptosilane coupling agent comprises the following steps: respectively preparing a tetraethyl orthosilicate solution and an ammonia ethanol solution, dripping the tetraethyl orthosilicate solution into the ammonia ethanol solution at a mixing volume ratio of 1:10-15 under stirring, continuing stirring and reacting for 1-2 hours after the dripping is completed, performing low-speed centrifugation at 2500 rpm for 5-15 minutes to remove precipitation, performing high-speed centrifugation at 13000 rpm for 15 minutes, separating the precipitation and washing it with anhydrous ethanol and deionized water in turn, and drying to obtain silicon dioxide nanoparticles; then dispersing the silicon dioxide nanoparticles in a 2-5 g / L mercaptosilane coupling agent solution, stirring and reacting at room temperature for 12-24 hours, separating the precipitation product and washing it with toluene and anhydrous ethanol in turn, and drying to obtain silicon dioxide nanoparticles modified by a mercaptosilane coupling agent.

5. The spherical silicon powder according to claim 4, characterized in that: The mercaptosilane coupling agent is selected from one or more of KH-580 and KH-590.

6. A method for preparing spherical silicon powder according to any one of claims 1 to 5, characterized in that: The surface-modified spherical silicon micropowder and the mercaptosilane coupling agent-modified silicon dioxide nanoparticles are mixed in a mass ratio of 1:2.5-4 and stirred evenly.

7. A packaging material comprising 30-50 parts by mass of epoxy resin, 5-20 parts by mass of curing agent, 0.5-10 parts by mass of curing accelerator, 10-50 parts by mass of spherical silicon powder according to any one of claims 1 to 5, 5-15 parts by mass of toughening agent, 1-5 parts by mass of release agent and 0.2-2 parts by mass of colorant.

8. The packaging material according to claim 7, characterized in that: The epoxy resin is selected from one or more of bisphenol epoxy resin and o-cresol epoxy resin; the curing agent is selected from one or more of dicyandiamide, aromatic amine, melamine and phenolic resin.

9. The packaging material according to claim 7, characterized in that: The curing agent is selected from one or more of dicyandiamide, aromatic amine, melamine and phenolic resin.

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