Composite silica powder as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of silica powder, and provides composite silica powder as well as a preparation method and application thereof. The preparation method comprises the following steps: sequentially crushing, pickling, drying and grinding quartzite ore to obtain silica powder, mixing the silica powder and wollastonite powder to obtain mixed powder, and reacting the mixed powder, a silane coupling agent and a solvent. The quartzite ore is subjected to all-directional refining treatment, so that the high purity and proper particle size distribution of the silica powder are guaranteed, the particle size distribution state of the composite silica powder is optimized, and the thermal deformation of the aluminum-based copper-clad plate is reduced by 70% or above compared with that of traditional silica powder; through the synergistic effect between the silica powder and the wollastonite powder and the good dispersity of the composite silica powder in the aluminum-based copper-clad plate, the heat conductivity coefficient of the aluminum-based copper-clad plate is increased by 20% or above; and through reasonable compounding and modification processes, firm chemical bonding is formed between the silica powder and the epoxy resin, so that the bonding strength of the aluminum-based copper-clad plate is improved by more than 35%.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon micropowder, and in particular to composite silicon micropowder and a preparation method and application thereof. Background Art

[0002] With the rapid advancement of electronic technology, the performance of electronic devices continues to improve, and the performance requirements for their internal components are becoming increasingly stringent. Aluminum-based copper-clad laminates (ACLs) serve as critical heat dissipation components and electrical connectors in electronic devices. Their performance directly impacts the performance and lifespan of these devices. Silicon micropowder is a common filler material for ACLs. Traditional ACLs often lack the required purity, particle size distribution, and compatibility with epoxy resins. For example, the difficulty in effectively removing impurities from quartzite ore results in low purity, impacting the electrical performance and reliability of the ACLs. The lack of effective particle size control makes it impossible to meet the diverse requirements of ACLs for silica micropowders of varying particle sizes, further impacting the thermal conductivity and mechanical properties of the ACLs. More critically, the poor compatibility of traditional ACLs with epoxy resins results in weak interfacial bonding during the composite process, which can easily lead to delamination, cracking, deformation, and warping during use, severely reducing the quality and service life of the ACLs. In addition, with the development of electronic equipment towards miniaturization, lightweight, high power density, etc., the heat dissipation performance and mechanical stability of aluminum-based copper clad laminates are also facing higher challenges.

[0003] Therefore, the research and development of composite silicon micropowder and its preparation method that can effectively overcome the above problems has become a research hotspot and key technical problem in the field of electronic materials. Summary of the Invention

[0004] The purpose of the present invention is to provide a composite silicon micropowder and a preparation method and application thereof in view of the deficiencies in the prior art.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing composite silicon micropowder, comprising the following steps:

[0007] 1) The quartzite ore is crushed, pickled, dried and ground in sequence to obtain silicon micropowder;

[0008] 2) mixing silicon micropowder and wollastonite powder to obtain a mixed powder;

[0009] 3) Mixing the mixed powder, silane coupling agent and solvent, and reacting them to obtain composite silicon powder.

[0010] Preferably, the acid solution used for pickling in step 1) is hydrochloric acid or sulfuric acid, the mass fraction of the acid solution is 5-15%, and the pickling time is 0.5-2h;

[0011] The drying temperature is 80-120° C., and the drying time is 3-6 hours.

[0012] Preferably, the grinding in step 1) is performed by ball milling or air flow milling, the rotation speed of the ball milling is 150-250 r / min, the ball milling time is 3-6 h, the ball-to-material ratio is 3-10:1, and the ball milling medium is zirconia beads;

[0013] The pressure of the jet mill is 0.6-1.2 MPa, the jet milling time is 1-3 hours, and the classifying wheel speed of the jet mill is 1200-2000 r / min.

[0014] Preferably, the D50 of the silicon micropowder in step 1) is 3-10 μm, and the particle size of the wollastonite powder in step 2) is 800-3000 mesh.

[0015] Preferably, in step 2), the mass ratio of the silicon micropowder to wollastonite powder is 1 to 5:1.

[0016] Preferably, the solvent in step 3) is anhydrous ethanol or acetone.

[0017] Preferably, in step 3), the mass of the silane coupling agent is 0.8-2% of the mass of the mixed powder, and the mass-to-volume ratio of the mixed powder to the solvent is 1 g: 3-6 mL.

[0018] Preferably, the reaction temperature in step 3) is 50-80° C., and the reaction time is 2-5 h; stirring is performed during the reaction, and the stirring speed is 100-200 r / min.

[0019] The present invention also provides composite silicon micropowder prepared by the preparation method.

[0020] The present invention also provides application of the composite silicon micropowder in aluminum-based copper-clad laminates.

[0021] The beneficial effects of the present invention include the following:

[0022] 1) The present invention effectively ensures the high purity and appropriate particle size distribution of silicon micropowder by means of fine processing such as crushing, pickling, sorting and grinding of quartzite ore, and composites silicon micropowder of different particle sizes with wollastonite powder to optimize the particle size distribution of silicon micropowder and make its structure denser, so that the thermal expansion coefficient of aluminum-based copper clad laminate during temperature changes is effectively adjusted, and the thermal deformation is significantly reduced. When tested in the range of 20 to 100°C, the thermal deformation of aluminum-based copper clad laminate can be reduced by more than 70% compared with traditional silicon micropowder, which can ensure the stability of electronic equipment at different operating temperatures; the synergistic effect between silicon micropowder of different particle sizes and wollastonite powder and the good dispersion of composite silicon micropowder in aluminum-based copper clad laminate enhance the thermal conduction path of the material, so that the thermal conductivity of the aluminum-based copper clad laminate is increased by more than 20%, meeting the heat dissipation requirements of electronic equipment, helping to improve the performance of electronic equipment and extend its service life.

[0023] 2) The present invention forms a strong chemical bond between silicon micropowder and epoxy resin through a reasonable composite process and a modification process of a silane coupling agent, significantly improving the bonding strength of the aluminum-based copper-clad laminate by more than 35% compared with traditional silicon micropowder, effectively preventing delamination and cracking problems during the use of the aluminum-based copper-clad laminate.

[0024] 3) The preparation method of the present invention can flexibly adjust the process parameters and raw material ratios according to actual needs, can meet the production of aluminum-based copper-clad laminates with different performance requirements, and has strong adaptability and operability; the composite silicon micropowder of the present invention can also effectively improve the deformation and warping problems of the aluminum-based copper-clad laminates, so that the aluminum-based copper-clad laminates have good thermal conductivity, insulation, mechanical strength and dimensional stability, etc., ensuring the normal operation and long-term reliability of electronic equipment, showing extremely important application value and broad application prospects, and at the same time having important significance for promoting the miniaturization and high performance development of electronic equipment. DETAILED DESCRIPTION

[0025] The present invention provides a method for preparing composite silicon micropowder, comprising the following steps:

[0026] 1) The quartzite ore is crushed, pickled, dried and ground in sequence to obtain silicon micropowder;

[0027] 2) mixing silicon micropowder and wollastonite powder to obtain a mixed powder;

[0028] 3) Mixing the mixed powder, silane coupling agent and solvent, and reacting them to obtain composite silicon powder.

[0029] In the present invention, the crushing in step 1) is preferably carried out using a jaw crusher. After the crushing, quartzite ore powder is obtained. The particle size of the quartzite ore powder is preferably 1 to 5 cm, more preferably 2 to 4 cm, and more preferably 3 to 3.5 cm.

[0030] In the present invention, after the crushing in step 1) is completed, it is preferred to first perform sorting, and then sequentially perform pickling, drying and grinding; the purity of the raw materials is ensured by sorting.

[0031] In the present invention, the acid solution used for pickling in step 1) is preferably hydrochloric acid or sulfuric acid, and the mass fraction of the acid solution is preferably 5-15%. When hydrochloric acid is used, the mass fraction of hydrochloric acid is more preferably 10-12%; when sulfuric acid is used, the mass fraction of sulfuric acid is more preferably 7-8%. The pickling time is preferably 0.5-2h, more preferably 1-1.8h, and more preferably 1.5h;

[0032] The drying temperature is preferably 80-120° C., more preferably 90-110° C., and more preferably 100-105° C.; the drying time is preferably 3-6 h, more preferably 4-5 h, and more preferably 4.5 h.

[0033] In the present invention, after the acid washing in step 1) is completed, it is preferred to first perform washing, and then sequentially perform drying and grinding; the reagent used in the washing is preferably water, and the washing is preferably stopped when the washing liquid reaches neutrality.

[0034] In the present invention, the grinding in step 1) is preferably performed by ball milling or airflow milling, the rotation speed of the ball mill is preferably 150 to 250 r / min, more preferably 180 to 230 r / min, and more preferably 200 r / min; the ball milling time is preferably 3 to 6 h, more preferably 4 to 5 h, and more preferably 4.5 h; the ball-to-material ratio is preferably 3 to 10:1, more preferably 5 to 8:1, and more preferably 6 to 7:1; the ball milling medium is preferably zirconia beads;

[0035] The pressure of the air flow mill is preferably 0.6-1.2 MPa, more preferably 0.7-1 MPa, more preferably 0.8-0.9 MPa; the air flow milling time is preferably 1-3 h, more preferably 1.5-2.5 h, more preferably 2 h; the classifying wheel speed of the air flow mill is preferably 1200-2000 r / min, more preferably 1400-1800 r / min, more preferably 1600 r / min.

[0036] In the present invention, the D50 of the silicon powder in step 1) is preferably 3-10 μm, more preferably 5-8 μm, and more preferably 6-7 μm; the particle size of the wollastonite powder in step 2) is preferably 800-3000 mesh, more preferably 1000-2500 mesh, and more preferably 1500-2000 mesh.

[0037] In the present invention, the mass ratio of the silicon micropowder to wollastonite powder in step 2) is preferably 1 to 5:1, more preferably 2 to 4:1, and even more preferably 3:1.

[0038] In the present invention, the mixing in step 2) is preferably stirring mixing, and the stirring mixing speed is preferably 800-1000 r / min, more preferably 900 r / min; the stirring mixing time is preferably 1-3 h, more preferably 2 h.

[0039] In the present invention, in step 2), two kinds of silicon micropowders with different D50 are preferably mixed with wollastonite powder.

[0040] In the present invention, the solvent in step 3) is preferably anhydrous ethanol or acetone.

[0041] In the present invention, the mass of the silane coupling agent in step 3) is preferably 0.8-2% of the mass of the mixed powder, more preferably 1-1.8%, and more preferably 1.2-1.5%; the mass volume ratio of the mixed powder to the solvent is preferably 1 g: 3-6 mL, more preferably 1 g: 4-5.5 mL, and more preferably 1 g: 4.5-5 mL.

[0042] In the present invention, the silane coupling agent in step 3) is preferably a silane coupling agent capable of forming a chemical bond with the epoxy resin, and is further preferably one or more of γ-aminopropyltriethoxysilane, γ-glycidyloxypropyltrimethoxysilane and N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane.

[0043] In the present invention, in step 3), the mixing is preferably performed by first mixing the mixed powder with the solvent and then adding the silane coupling agent.

[0044] In the present invention, the temperature of the reaction in step 3) is preferably 50-80°C, more preferably 60-70°C, and more preferably 65°C; the reaction time is preferably 2-5h, more preferably 3-4.5h, and more preferably 3.5-4h; stirring is preferably performed during the reaction, and the stirring speed is preferably 100-200r / min, more preferably 120-180r / min, and more preferably 150r / min.

[0045] The present invention also provides composite silicon micropowder prepared by the preparation method.

[0046] The present invention also provides application of the composite silicon micropowder in aluminum-based copper-clad laminates.

[0047] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0048] In the embodiments of the present invention, the quartzite ore is quartzite ore from Dafen area, Suichuan County, Jiangxi Province, and the wollastonite powder is GY series wollastonite powder produced by Jiangxi Guangyuan Chemical Co., Ltd.

[0049] Example 1

[0050] Quartzite ore is crushed to a 3cm particle size using a jaw crusher. Quartzite ore powder is then sorted using a mechanical vibrating screen to remove particles that do not meet particle size requirements or contain significant impurities. The sorted quartzite ore powder is acid-washed with 10% hydrochloric acid for 1 hour and then rinsed with deionized water until the rinse solution is neutral. The washed quartzite ore powder is dried at 100°C for 4 hours to obtain dry quartzite ore powder. The dried quartzite ore powder is then ball-milled at 200 rpm for 4 hours using zirconia beads as the milling medium at a ball-to-batch ratio of 6:1 to obtain silicon micropowder with a D50 of 6μm.

[0051] Silica powder and wollastonite powder (the particle size of wollastonite powder is 1500 mesh) with a mass ratio of 3:1 are placed in a high-speed mixer and stirred at a speed of 800 r / min for 2 hours to obtain a mixed powder. The mixed powder is dispersed in anhydrous ethanol (the mass volume ratio of the mixed powder to anhydrous ethanol is 1g:5mL), and then γ-aminopropyltriethoxysilane (the mass of γ-aminopropyltriethoxysilane is 1.5% of the mass of the mixed powder) is added to obtain a mixture. The mixture is stirred and reacted at 65°C at a speed of 150 r / min for 3 hours to obtain composite silica powder.

[0052] Example 2

[0053] Quartzite ore was crushed to a 4cm particle size using a jaw crusher. Quartzite ore powder was then sorted using a mechanical vibrating screen to remove particles that did not meet the particle size requirements or contained significant impurities. The sorted quartzite ore powder was acid-washed with 8% sulfuric acid for 1.5 hours and then washed with deionized water until the washing solution was neutral. The washed quartzite ore powder was dried at 110°C for 3 hours to obtain dry quartzite ore powder. The dried quartzite ore powder was then jet milled at a pressure of 0.9 MPa and a classifying impeller speed of 1200 r / min for 2 hours to obtain silica micropowder with a D50 of 8μm. The dried quartzite ore powder was then jet milled at a pressure of 0.7 MPa and a classifying impeller speed of 1800 r / min for 1.5 hours to obtain silica micropowder with a D50 of 5μm.

[0054] Silica powder with a D50 of 5 μm and silica powder with a D50 of 8 μm were mixed in a mass ratio of 2:1 to obtain a mixed silica powder. The mixed silica powder and wollastonite powder (the particle size of the wollastonite powder is 2000 mesh) with a mass ratio of 4:1 were placed in a high-speed mixer and stirred at a speed of 800 r / min for 2.5 hours to obtain a mixed powder. The mixed powder was dispersed in acetone (the mass volume ratio of the mixed powder to acetone was 1 g: 4 mL), and then γ-glycidyloxypropyltrimethoxysilane (the mass of γ-glycidyloxypropyltrimethoxysilane was 1% of the mass of the mixed powder) was added to obtain a mixture. The mixture was stirred and reacted at 70°C at a speed of 200 r / min for 4 hours to obtain composite silica powder.

[0055] Example 3

[0056] A jaw crusher was used to crush the quartzite ore into 2cm particle size quartzite ore powder. Fines that did not meet the particle size requirements and those with obvious impurities were removed through manual sorting and wind screening equipment. The sorted quartzite ore powder was acid-washed with 12% hydrochloric acid for 1.5 hours and then rinsed with deionized water until the rinse solution was neutral. The washed quartzite ore powder was dried at 90°C for 5 hours to obtain dry quartzite ore powder. The dried quartzite ore powder was then placed in a ball mill using zirconia beads as the milling medium at a ball-to-batch ratio of 3:1 and milled at 180 rpm for 5 hours to obtain silicon micropowder with a D50 of 4μm.

[0057] Silica powder and wollastonite powder (the particle size of wollastonite powder is 2500 mesh) with a mass ratio of 4:1 are placed in a planetary mixer and stirred at a speed of 1000 r / min for 2 hours to obtain a mixed powder. The mixed powder is dispersed in anhydrous ethanol (the mass volume ratio of the mixed powder to anhydrous ethanol is 1g:4.5mL), and then N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane (the mass of N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane is 1.8% of the mass of the mixed powder) is added to obtain a mixture. The mixture is stirred and reacted at 70°C at a speed of 100 r / min for 3.5 hours to obtain composite silica powder.

[0058] Example 4

[0059] Quartzite ore was crushed to a 3.5 cm particle size using a jaw crusher. Quartzite ore powder was then sorted using a mechanical vibrating screen to remove particles that did not meet the particle size requirements or contained significant impurities. The sorted quartzite ore powder was acid-washed with 7% sulfuric acid for 1.8 hours and then washed with deionized water until the washing solution was neutral. The washed quartzite ore powder was dried at 105°C for 4.5 hours to obtain dry quartzite ore powder. The dried quartzite ore powder was then jet milled at a pressure of 0.8 MPa and a classifying impeller speed of 1400 r / min for 3 hours to obtain silica micropowder with a D50 of 7 μm. The dried quartzite ore powder was jet milled at a pressure of 0.6 MPa and a classifying impeller speed of 2000 r / min for 1 hour to obtain silica micropowder with a D50 of 4 μm.

[0060] Silica powder with a D50 of 4 μm and silica powder with a D50 of 7 μm were mixed in a mass ratio of 3:2 to obtain a mixed silica powder. The mixed silica powder and wollastonite powder (the particle size of the wollastonite powder is 3000 mesh) with a mass ratio of 3:1 were placed in a high-speed mixer and stirred at a speed of 800 r / min for 3 hours to obtain a mixed powder. The mixed powder was dispersed in acetone (the mass volume ratio of the mixed powder to acetone was 1 g: 5.5 mL), and then γ-aminopropyltriethoxysilane (the mass of γ-aminopropyltriethoxysilane was 1.2% of the mass of the mixed powder) was added to obtain a mixture. The mixture was stirred at 65°C at a speed of 120 r / min for 4.5 hours to obtain a composite silica powder.

[0061] Comparative Example 1

[0062] Traditional silicon micropowder: A mixture of GS-004 silicon micropowder and GS-010 silicon micropowder produced by Jiangxi Guangyuan Chemical Co., Ltd., in which the mass ratio of GS-004 silicon micropowder to GS-010 silicon micropowder is 1:2.

[0063] Aluminum-based copper-clad laminates were prepared using the silicon micropowders from Examples 1 to 4 and Comparative Example 1, respectively. The preparation method was as follows: the silicon micropowder was mixed with N,N-dimethylformamide (the mass-to-volume ratio of silicon micropowder to N,N-dimethylformamide was 1g:5mL) and stirred at 150 rpm for 20 minutes until uniformly mixed, thereby obtaining a mixed system. A silane coupling agent, KH-560, was added to the mixed system (the mass of KH-560 was 1.2% of the mass of the silicon micropowder), and the mixture was reacted at 70°C for 4 hours to obtain a surface-modified silicon micropowder dispersion. The silicon micropowder dispersion, curing agent, dicyandiamide, and accelerator, imidazole, were sequentially added to epoxy resin E51 and stirred at 800 rpm until the powders were uniformly dispersed and free of agglomerates, thereby obtaining an adhesive. The adhesive contained 40 parts silicon micropowder, 100 parts epoxy resin, 8 parts dicyandiamide, and 0.5 parts imidazole.

[0064] The aluminum substrate surface was polished with sandpaper to a surface roughness of 1.6 to 3.2 μm (Ra), and the oxide film and oil stains were removed. The substrate was then cleaned with ethanol. A 2% solution of silane coupling agent KH-560 was then applied to the surface for 20 minutes to enhance adhesion to the adhesive.

[0065] The glue was evenly applied to the treated aluminum substrate using a coating machine, with a thickness of 100 μm. The adhesive was then heat-cured at a pressure of 2 MPa. The curing schedule for the heat-curing process was: initial curing at 100°C for 1 hour, followed by full curing at 150°C for 2 hours, and finally, further curing at 180°C for 3 hours.

[0066] The bonding strength of the aluminum-based copper clad laminate was tested in accordance with GB / T 7124-2008, the thermal deformation of the aluminum-based copper clad laminate in the range of 2 to 100°C was tested in accordance with GB / T1634.2-2004, and the thermal conductivity of the aluminum-based copper clad laminate was tested in accordance with GB / T22588-2008. The test results are shown in Table 1.

[0067] Table 1 Performance test results of aluminum-based copper-clad laminates prepared with different silicon micropowders

[0068] Silica powder types Bonding strength / MPa Thermal deformation / mm Thermal conductivity / W / (m·K) Example 1 35 0.12 3.2 Example 2 32 0.15 3.0 Example 3 38 0.16 3.5 Example 4 36 0.13 3.3 Comparative Example 1 25 0.6 2.5

[0069] As can be seen from Table 1, due to the good compounding and modification process, the composite silicon micropowder of the present invention is more tightly bonded to the epoxy resin, resulting in an increase in the bonding strength of the aluminum-based copper-clad laminate by 38-52% compared to conventional silicon micropowder. The structural optimization of the composite silicon micropowder and its good compatibility with the epoxy resin reduce the difference in thermal expansion of the aluminum-based copper-clad laminate at different temperatures, inhibit thermal deformation, and have good thermal stability. The synergistic effect of the silicon micropowder and wollastonite powder in the composite silicon micropowder promotes heat conduction, enhances the thermal conduction path, and improves the thermal conductivity of the aluminum-based copper-clad laminate. The aluminum-based copper-clad laminate prepared with the composite silicon micropowder of the present invention is superior to conventional silicon micropowder in terms of bonding strength, thermal deformation, and thermal conductivity.

[0070] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing composite silicon micropowder, characterized in that: The following steps are included: 1) The quartzite ore is crushed, pickled, dried and ground in sequence to obtain silicon micropowder; 2) mixing silicon micropowder and wollastonite powder to obtain a mixed powder; 3) Mixing the mixed powder, silane coupling agent and solvent, and reacting them to obtain composite silicon powder.

2. The preparation method according to claim 1, characterized in that The acid solution used in the pickling step 1) is hydrochloric acid or sulfuric acid, the mass fraction of the acid solution is 5-15%, and the pickling time is 0.5-2h; The drying temperature is 80-120° C., and the drying time is 3-6 hours.

3. The preparation method according to claim 2, characterized in that Step 1) The grinding is performed by ball milling or air jet milling, the rotation speed of the ball milling is 150-250 r / min, the ball milling time is 3-6 hours, the ball-to-material ratio is 3-10:1, and the ball milling medium is zirconia beads; The pressure of the jet mill is 0.6-1.2 MPa, the jet milling time is 1-3 hours, and the classifying wheel speed of the jet mill is 1200-2000 r / min.

4. The preparation method according to claim 2 or 3, characterized in that The D50 of the silicon micropowder in step 1) is 3 to 10 μm, and the particle size of the wollastonite powder in step 2) is 800 to 3000 mesh.

5. The preparation method according to claim 4, characterized in that In step 2), the mass ratio of the silicon micropowder to the wollastonite powder is 1 to 5:

1.

6. The preparation method according to claim 5, characterized in that Step 3) The solvent is anhydrous ethanol or acetone.

7. The preparation method according to claim 5 or 6, characterized in that: Step 3) The mass of the silane coupling agent is 0.8-2% of the mass of the mixed powder, and the mass-to-volume ratio of the mixed powder to the solvent is 1 g: 3-6 mL.

8. The preparation method according to claim 7, characterized in that Step 3) The reaction temperature is 50-80° C., and the reaction time is 2-5 h. Stirring is performed during the reaction at a speed of 100-200 r / min.

9. Composite silicon micropowder prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the composite silicon micropowder according to claim 9 in aluminum-based copper-clad laminates.