Preparation method of composite powder and resin composite material, and copper-clad plate

Abstract

The invention discloses a preparation method of composite powder and a resin composite material and a copper-clad plate, and the preparation method of the composite powder comprises the following steps: carrying out ball milling on aluminum nitride and ceramic powder with a ball milling medium comprising ethanol, and drying to obtain a first blocky solid; pre-sintering the first blocky solid to obtain an intermediate; after the intermediate is smashed and pressed, the intermediate is wrapped with a film layer with the isolation function and treated under an oil press, and a second blocky solid is obtained; and carrying out solid-phase sintering on the second blocky solid to obtain the composite powder. The mixing uniformity of the aluminum nitride and the ceramic powder in the composite powder is improved, the aluminum nitride has certain hydrolysis resistance, and the overall chemical stability is good. The resin composite material is prepared from the prepared composite powder and a resin material through co-condensation, and has more stable performance and structure. The copper-clad plate based on the composite powder or resin composite material has better heat-conducting property, lower thermal expansion coefficient and lower dielectric loss.

Description

Technical Field

[0001] This application relates to the field of material preparation, and particularly to a preparation method of composite powder and resin composite material, and a copper clad laminate. Background Art

[0002] As one of the core raw materials of printed circuit boards (PCBs), copper clad laminates (CCLs) are widely used in the field of communication electronics. With the rapid development of 5G communication technology and the iterative upgrade of electronic components, the market has put forward higher requirements for the performance of copper clad laminates.

[0003] Traditional copper clad laminates usually use polytetrafluoroethylene (PTFE) as the main material of the dielectric layer. However, resin materials have problems such as poor thermal conductivity and large thermal expansion coefficient. When glass fiber cloth is impregnated with resin to form a prepreg, the glass fiber effect will cause high dielectric loss and heat generation, which will further lead to signal loss. Seriously, it can cause the reduction of the service life of electronic devices or even failure. Summary of the Invention

[0004] In view of this, this application provides a preparation method of composite powder and resin composite material, and a copper clad laminate to solve at least one of the above technical problems.

[0005] To achieve the above object, in the first aspect, this application provides a preparation method of composite powder. The preparation method includes: ball-milling aluminum nitride and ceramic powder, where the ball-milling medium for ball-milling includes ethanol, and after drying, a first massive solid is obtained; pre-sintering the first massive solid to obtain an intermediate; and after crushing and pressing the intermediate, wrapping the intermediate with a film layer having an insulating effect and processing it under a hydraulic press to obtain a second massive solid; performing solid-phase sintering on the second massive solid to obtain composite powder.

[0006] Ball milling and mixing is beneficial to improving the mixing uniformity of aluminum nitride and ceramic powder. Meanwhile, it is conducive to the refinement of powder particles, increasing the specific surface area of powder particles, which is beneficial to the contact area between powder particles during the subsequent solid-phase sintering process, thereby improving the solid solubility. Using anhydrous ethanol as the ball milling medium is beneficial to reducing the hydrolysis of aluminum nitride to form aluminum hydroxide during the ball milling process, which is conducive to reducing the formation of aluminum oxide during the subsequent sintering process, avoiding the reduction of the thermal conductivity of the composite powder due to excessive aluminum oxide, and maintaining a large amount of aluminum nitride is beneficial to the formation of the thermal conduction network during the subsequent solid-phase sintering process, which is conducive to improving the uniformity of solid-phase sintering. By pre-sintering and pulverizing the intermediate obtained from the pre-sintering, it is beneficial to remove the volatile components in the raw materials, better fix the powder materials (aluminum nitride and ceramic powder) in the raw materials, and improve the mixing uniformity of aluminum nitride and ceramic powder. At the same time, it is also beneficial to reduce the shrinkage rate after sintering of the intermediate to optimize the microstructure of the powder materials. By pressing, wrapping, and applying oil pressure to the pulverized intermediate, a denser block can be formed. Increasing the pressure between the powder and particles before solid-phase sintering by cold isostatic pressing is beneficial to improving the solid solubility and the uniformity of solid-phase sintering. Through solid-phase sintering, the solid solution or partial solid solution of aluminum nitride and ceramic powder is realized, making the microstructure of aluminum nitride more uniform, which is beneficial to promoting the formation of a uniform and high-thermal-conductivity sialon solid solution phase. At the same time, the solid-solved aluminum nitride has a more matching thermal expansion coefficient, which helps to reduce the stress concentration and cracking risk of the copper clad laminate under temperature changes; solid solution also reduces the number of interfaces between powder particles, which is conducive to reducing the charge accumulation and leakage at the interfaces and enhancing the electrical insulation of the material; moreover, the chemical stability of aluminum nitride after solid-phase sintering is better, which helps to improve the long-term use performance of the copper clad laminate.

[0007] Based on the first aspect, in some possible implementation manners, the preparation method further includes: ball milling and pre-sintering the pre-sintered product again to obtain an intermediate. This step is beneficial to further removing the volatile components in the raw materials.

[0008] Based on the first aspect, in some possible implementation manners, after the solid-phase sintering, the preparation method further includes sieving the product of the solid-phase sintering using a sieve, and the mesh number of the sieve is 500 to 5000. Controlling the particle size of the composite powder within this range is beneficial to reducing the dielectric loss after the composite powder supports the copper clad laminate.

[0009] Based on the first aspect, in some possible implementation manners, after the solid-phase sintering, the preparation method further includes mixing a modifier with the product of the solid-phase sintering, and the modifier includes grease, so that the surface of the product of the solid-phase sintering is grafted with a hydrophobic group to obtain a composite powder. Modifying with grease is beneficial to improving the hydrophobicity and hydrolysis resistance of the composite powder, thereby being conducive to reducing the hydrolysis of aluminum nitride in the composite powder.

[0010] Based on the first aspect, in some possible implementation manners, the grease includes one or more of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β(aminoethyl)-γ-aminopropylmethyldimethoxysilane, N-β(aminoethyl)-γ-aminopropyltriethoxysilane, and N-β(aminoethyl)-γ-aminopropylmethyldiethoxysilane.

[0011] Based on the first aspect, in some possible implementation manners, the mass ratio of the grease to the product of solid-phase sintering is 0.5% to 5%. This mass ratio is beneficial to promoting the modification effect of the grease on the solid-phase sintering product.

[0012] Based on the first aspect, in some possible implementation manners, the modifier further includes water and ethanol, and the mass ratio of water, ethanol to the grease is 1:(1~3):(5~15). The above-mentioned modifier and controlling the mass ratio between the components of the modifier are beneficial to promoting the modification treatment of the composite powder.

[0013] Based on the first aspect, in some possible implementation manners, the temperature of pre-sintering is 1000 °C to 1200 °C. This pre-sintering temperature is beneficial to further promoting the removal of volatile components.

[0014] Based on the first aspect, in some possible implementation manners, the pressure of the hydraulic press is 1 MPa to 2 MPa. This pressure is beneficial to further promoting the forming effect of the block, making the block formed by cold isostatic pressing more dense.

[0015] Based on the first aspect, in some possible implementation manners, the temperature of solid-phase sintering is 1400 °C to 1800 °C. This solid-phase sintering temperature is beneficial to further enhancing the solid solution effect.

[0016] In the second aspect, the present application provides a preparation method of a resin composite material, and this preparation method includes: obtaining the resin composite material by co-precipitation of the composite powder prepared by the above-mentioned preparation method of the composite powder and a resin material. The resin composite material obtained by co-precipitation has more stable performance and structure.

[0017] Based on the second aspect, in some possible implementation manners, the co-precipitation includes mixing the dispersion liquid of the composite powder with the colloidal resin material to obtain a mixed solution, and stirring the mixed solution to cause co-precipitation. By forming the composite powder into a dispersion liquid, mixing it with the resin colloid, and stirring, it is beneficial to promoting the occurrence of the co-precipitation effect.

[0018] Based on the second aspect, in some possible implementation manners, the preparation method further includes filtering and drying the mixed solution after co-precipitation to obtain the resin composite material.

[0019] In a third aspect, the present application provides a copper clad laminate, which includes a copper foil layer and a dielectric layer arranged in a stacked manner.

[0020] Based on the third aspect, in some possible implementation manners, the dielectric layer includes a resin material and a composite powder prepared by the above-mentioned preparation method of the composite powder.

[0021] Based on the third aspect, in some possible implementation manners, the dielectric layer includes a resin composite material prepared by the above-mentioned preparation method of the resin composite material.

[0022] The dielectric layer of the above copper clad laminate has a composite powder of aluminum nitride ceramic powder with high densification and high uniformity, providing a stable heat conduction structure and signal transmission structure for the copper clad laminate. Therefore, the copper clad laminate has good heat conduction performance, a low coefficient of thermal expansion, and a low dielectric loss. Description of the Drawings

[0023] Figure 1 In (a) is a scanning electron microscope image of aluminum nitride without grease modification after hydrolysis for 24 h provided by the present application, Figure 1 In (b) is a scanning electron microscope image of aluminum nitride with grease modification after hydrolysis for 24 h provided by the present application.

[0024] Figure 2 is a scanning electron microscope image of the resin composite material provided in Example 1 of the present application. Detailed Embodiments

[0025] The embodiments of the present application will be described in detail below. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present application, and should not be construed as a limitation to the present application; it should be noted that unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs; without conflict, the implementation manners and features in the implementation manners of the present application can be combined with each other; many specific details are set forth in the following description to fully understand the present application, and the described implementation manners are only a part of the implementation manners of the present application, rather than all the implementation manners.

[0026] To improve the problems existing in traditional copper clad laminates, related technologies often compound resin materials with ceramic powder to obtain a composite material for copper clad laminates with a lower coefficient of thermal expansion. However, the thermal conductivity of this composite material is still difficult to meet the requirements of certain specific usage conditions. Related technologies also mix aluminum nitride in the ceramic powder to obtain a composite powder, and then compound it with the resin material to further make up for the thermal conductivity of the composite material.

[0027] However, it is difficult to mix different inorganic materials evenly. When aluminum nitride is mixed in ceramic powder, uneven mixing is likely to occur, resulting in unstable material properties and structures, which is not conducive to improving the mechanical strength of the copper clad laminate and increases the manufacturing difficulty of the copper clad laminate. Moreover, the research of this application finds that due to the relatively active surface chemical properties of aluminum nitride, the aluminum nitride in the composite material is easily hydrolyzed to form aluminum hydroxide, which causes phonon conduction to be blocked, thereby reducing the thermal conductivity of the material. At the same time, the instability of the composite material also leads to poor weather resistance.

[0028] Based on this, this application improves the preparation method of the composite powder of ceramic powder and aluminum nitride to improve the uniformity and hydrolysis resistance of the obtained composite powder, and composites the obtained composite powder with a resin material to be used for preparing a copper clad laminate, so as to achieve the purpose of improving the thermal conductivity, mechanical strength and service life of the copper clad laminate.

[0029] One embodiment of this application provides a copper clad laminate, which includes a copper foil layer and a dielectric layer arranged in a stacked manner. The dielectric layer includes a resin composite material. The resin composite material includes a composite powder and a resin material. The composite powder includes aluminum nitride and ceramic powder. The resin material includes PTFE. The aluminum nitride ceramic powder composite powder with high densification and high uniformity in the dielectric layer of the above copper clad laminate provides a stable thermal conduction structure and signal transmission structure for the copper clad laminate. Therefore, the copper clad laminate has good thermal conductivity, a low coefficient of thermal expansion and low dielectric loss.

[0030] Among them, the resin composite material is prepared by co-precipitation of the composite powder and the resin material. The resin composite material obtained by co-precipitation has more stable properties and structures.

[0031] Among them, the composite powder is prepared from aluminum nitride and ceramic powder by the following preparation method: ball-mill aluminum nitride and ceramic powder. The ball-milling medium for ball-milling includes ethanol, and a first block solid is obtained after drying; pre-sinter the first block solid to obtain an intermediate; and after pulverizing and pressing the intermediate, wrap the intermediate with a film layer having an insulating effect and perform treatment under a hydraulic press to obtain a second block solid; perform solid-phase sintering on the second block solid to obtain the composite powder.

[0032] Ball milling and mixing are beneficial to improving the mixing uniformity of aluminum nitride and ceramic powder. At the same time, it is conducive to the refinement of powder particles, increasing the specific surface area of powder particles, which is beneficial to the contact area between powder particles during the subsequent solid-phase sintering process, thereby improving the solid solubility. Using anhydrous ethanol as the ball milling medium is beneficial to reducing the hydrolysis of aluminum nitride to form aluminum hydroxide during the ball milling process, which is conducive to reducing the formation of aluminum oxide during the subsequent sintering process, avoiding the reduction of the thermal conductivity of the composite powder due to excessive aluminum oxide, and maintaining a large amount of aluminum nitride is beneficial to the formation of a thermal conduction network during the subsequent solid-phase sintering process, which is conducive to improving the uniformity of solid-phase sintering. By pre-sintering and crushing the intermediate obtained from the pre-sintering, it is beneficial to remove the volatile components in the raw materials to better fix the powder materials (aluminum nitride and ceramic powder) in the raw materials, and improve the mixing uniformity of aluminum nitride and ceramic powder. At the same time, it is also beneficial to reduce the shrinkage rate after sintering of the intermediate to optimize the microstructure of the powder materials. By pressing, wrapping, and applying oil pressure to the crushed intermediate, a denser block can be formed. By cold isostatic pressing, the pressure between the powder and particles before solid-phase sintering is increased, which is beneficial to improving the solid solubility and the uniformity of solid-phase sintering. Through solid-phase sintering, the solid solution or partial solid solution of aluminum nitride and ceramic powder is realized, making the microstructure of aluminum nitride more uniform, which is beneficial to promoting the formation of a uniform and high-thermal-conductivity sialon solid solution phase. At the same time, the solid-solution aluminum nitride has a more matched thermal expansion coefficient, which helps to reduce the stress concentration and cracking risk of the copper clad laminate under temperature changes; the solid solution also reduces the number of interfaces between powder particles, which is beneficial to reducing the charge accumulation and leakage at the interfaces and enhancing the electrical insulation of the material; and, the chemically stable aluminum nitride after solid-phase sintering is better, which helps to improve the long-term use performance of the copper clad laminate.

[0033] Another embodiment of the present application provides a method for preparing a composite powder, including: Step 1: Ball mill aluminum nitride and ceramic powder. The ball milling medium for ball milling includes ethanol. After drying, a first block solid is obtained, and the first block solid is pre-sintered.

[0034] In some embodiments, the ceramic powder includes one or more of silicon dioxide, titanium dioxide, boron oxide, and silicon nitride to achieve the synergistic adjustment of other properties, such as subsequent processability, etc.

[0035] In some embodiments, the ceramic powder includes silica powder.

[0036] In some embodiments, based on the total mass of aluminum nitride and ceramic powder, the mass ratio of aluminum nitride is greater than 0 and less than or equal to 10%. For example, the mass ratio of aluminum nitride can be 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5% or any value within the range composed of any two of the above values. Providing enough ceramic powder is beneficial to making the obtained composite powder have good mechanical strength.

[0037] In some embodiments, the temperature of pre-sintering is 1000 °C to 1200 °C. For example, the temperature of pre-sintering can be 1000 °C, 1050 °C, 1100 °C, 1150 °C, 1200 °C or any value within the range formed by any two of the above values. Controlling the pre-sintering temperature within the above range is beneficial to further promote the removal of volatile components.

[0038] Step 2: Ball-mill and pre-sinter the pre-sintered product again to obtain an intermediate. This step is beneficial to further remove the volatile components in the raw materials.

[0039] Step 3: After crushing and pressing the intermediate, wrap the intermediate with a film layer having an insulating effect and process it under a hydraulic press to obtain a second massive solid, and perform solid-phase sintering on the second massive solid.

[0040] In some embodiments, the pressure of the hydraulic press is 1 MPa to 2 MPa. For example, the pressure of the hydraulic press can be 1 MPa, 1.1 MPa, 1.2 MPa, 1.3 MPa, 1.4 MPa, 1.5 MPa, 1.6 MPa, 1.7 MPa, 1.8 MPa, 1.9 MPa, 2 MPa or any value within the range formed by any two of the above values. Controlling the pressure of the hydraulic press within the above range is beneficial to further promote the forming effect of the block, making the block formed by cold isostatic pressing more dense.

[0041] In some embodiments, the temperature of solid-phase sintering is 1400 °C to 1800 °C. For example, the temperature of solid-phase sintering can be 1400 °C, 1450 °C, 1500 °C, 1550 °C, 1600 °C, 1650 °C, 1700 °C, 1750 °C, 1800 °C or any value within the range formed by any two of the above values. Controlling the temperature of solid-phase sintering within the above range is beneficial to further enhance the solid solution effect.

[0042] In some embodiments, crushing includes grinding or ball-milling.

[0043] Step 4: Screen the product of solid-phase sintering, and the mesh number of the sieve is 500 to 5000. For example, the mesh number of the sieve can be 500, 600, 700, 800, 900, 1000, 2000, 3000, 4000, 5000 or any value within the range formed by any two of the above values. Controlling the particle size of the composite powder within this range is beneficial to reduce the dielectric loss after the composite powder supports the copper clad laminate.

[0044] Step 5: Mix the modifier with the sieved solid-phase sintered product. The modifier includes grease, so that hydrophobic groups are grafted onto the surface of the solid-phase sintered product to obtain a composite powder. Modification with grease is beneficial to improving the hydrophobicity and hydrolysis resistance of the composite powder, thereby facilitating the reduction of the hydrolysis of aluminum nitride in the composite powder.

[0045] In some embodiments, the grease includes one or more of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β(aminoethyl)-γ-aminopropylmethyldimethoxysilane, N-β(aminoethyl)-γ-aminopropyltriethoxysilane, and N-β(aminoethyl)-γ-aminopropylmethyldiethoxysilane. It can graft hydrophobic groups onto the surface of the solid-phase sintered product, thereby facilitating the improvement of the hydrophobicity and hydrolysis resistance of the composite powder, and thus facilitating the reduction of the hydrolysis of aluminum nitride in the composite powder.

[0046] In some embodiments, the mass ratio of the grease to the solid-phase sintered product is 0.5% to 5%. For example, the mass ratio of the grease to the solid-phase sintered product can be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any value within the range composed of any two of the above values. Controlling the mass ratio of the grease to the solid-phase sintered product within the above range is beneficial to promoting the modification effect of the grease on the solid-phase sintered product.

[0047] In some embodiments, the modifier further includes water and ethanol, and the mass ratio of water, ethanol to the grease is 1:(1~3):(5~15). For example, the mass ratio of water, ethanol to the grease can be 1:1:5, 1:2:5, 1:3:5, 1:1:8, 1:1:10, 1:1:12, 1:1:15, 1:3:15, or any value within the range composed of any two of the above values. The above modifier and controlling the mass ratio between the components of the modifier within the above range are beneficial to promoting the modification treatment of the composite powder.

[0048] Another embodiment of the present application also provides a method for preparing a resin composite material, including: The first step: Mix the composite powder and water to obtain a dispersion of the composite powder, mix the dispersion of the composite powder and the emulsion resin material, and stir to cause co-precipitation of the mixed solution.

[0049] In some embodiments, the temperature of the mixed solution is 15 °C to 50 °C. For example, the temperature of the mixed solution can be 15 °C, 20 °C, 25 °C, 30 °C, 35 °C, 40 °C, 50 °C to promote the occurrence of co-precipitation.

[0050] The second step: Filter the co-precipitated mixed solution to obtain a resin composite material.

[0051] In some embodiments, after filtering the co - condensate mixture, drying is further included.

[0052] The solution of the present application will be explained below in conjunction with embodiments. Those skilled in the art will understand that the following examples are only for explaining the present application and should not be construed as a limitation of the present application. Unless otherwise stated, the reagents, software, and instruments involved in the following embodiments that are not specifically stated are all commercially available products or open - source.

[0053] Example 1: (1) A composite powder, the preparation method of which includes: The first step: Using anhydrous ethanol as the ball - milling medium, zirconia as the ball - milling stones, adding aluminum nitride and silicon micro - powder powders in a ratio of 1:10 as the ball - milling materials, and ball - milling in a nylon ball - milling tank with a planetary ball - mill for 18 h. Among them, the mass ratio of the ball - milling materials, ball - milling medium, and ball - milling stones is 2:3:4.

[0054] The second step: Drying the obtained ball - milling materials at 80 °C, sieving with a 50 - mesh sieve, placing the sieved powder in a nitrogen atmosphere at 1000 °C for pre - sintering for 2 h, with a heating rate of 5 °C / min starting from room temperature, setting the cooling rate to 5 °C / min, and waiting for natural cooling after cooling to 500 °C to obtain an intermediate.

[0055] The third step: Using anhydrous ethanol as the ball - milling medium, zirconia as the ball - milling stones, and the above - mentioned intermediate as the ball - milling material, and ball - milling in a nylon ball - milling tank with a planetary ball - mill for 24 h.

[0056] The fourth step: Drying the obtained ball - milling materials at 80 °C, sieving with a sieve, placing the sieved powder in a mold to press into a denser block, then transferring the block into a rubber sleeve with a thickness of 0.03 mm, evacuating the air in the rubber sleeve by vacuuming, sealing the mouth to wrap the block, putting the wrapped block into a hydraulic press, ensuring that it is completely immersed below the liquid level, and maintaining at a pressure of 1 MPa for 3 min.

[0057] The fifth step: Taking out the wrapped block after hydraulic pressing, placing it in a nitrogen atmosphere at 1400 °C for solid - phase sintering for 2 h, with a heating rate of 5 °C / min starting from room temperature, setting the cooling rate to 5 °C / min, and waiting for natural cooling after cooling to 500 °C.

[0058] The sixth step: Sieving the sintered product obtained in the fifth step with 600 - mesh, 1000 - mesh, and 2000 - mesh sieves to obtain sintered products with different particle sizes.

[0059] Step 7: Mix deionized water, ethanol and γ-aminopropyltriethoxysilane in a constant temperature oil bath at a mass ratio of 2:48:1 for 2 h to obtain a mixed solution; then take the 1000-mesh sieved sintered product obtained in the sixth step, the mass ratio of γ-aminopropyltriethoxysilane to the sintered product is 2%, place it in a powder mixer, set the speed to 5000 r / min for dispersion; quickly add the above mixed solution into the powder mixer by atomization method, mix for 6 h, and obtain a composite powder.

[0060] (2) A resin composite material, the preparation method of which comprises: Step 1: Disperse the composite powder obtained in (1) in deionized water to obtain a dispersion of the composite powder, add PTFE emulsion to the dispersion, continue stirring, and control the temperature to 20°C to allow co-coagulation to occur, wherein the mass ratio of the composite powder, deionized water and PTFE emulsion is 1:20:1.

[0061] Step 2: After the condensate appears, stop stirring, filter the condensate using a 300-mesh screen, and freeze-dry at -50 °C for 48 h to obtain a resin composite material.

[0062] (3) A copper clad laminate, the preparation method of which comprises: The resin composite material obtained in (2) is subjected to aging, calendering, double-sided copper cladding and high-temperature pressing to obtain a copper clad laminate.

[0063] Comparative Example 1: The difference from Example 1 is that in the first step of (1), the ball mill material is only silicon powder, and no aluminum nitride is added. Therefore, ball milling, cold isostatic pressing and solid phase reaction are not required. The rest of the modification, condensation and copper clad laminate preparation processes are the same as those in Example 1.

[0064] Comparative Example 2: The difference from Example 1 is that in (1), the composite powder is obtained by simply blending aluminum nitride and silicon powder and then pre-sintering. No ball milling, pressing, wrapping, oil pressing and solid phase sintering are performed. The remaining modification and condensation, copper clad laminate preparation process are the same as in Example 1.

[0065] This application also uses aluminum nitride that has not been modified with oil and fat to conduct hydrolysis reaction tests. The hydrolysis time is 24 hours to verify the effect of oil modification on the hydrolysis resistance of aluminum nitride. This application uses scanning electron microscopy (SEM) to test the morphology of the above two aluminum nitrides after hydrolysis. Please refer to Figure 1 , Figure 1 (a) is aluminum nitride that has not been modified with oil and fat. It obviously agglomerates after hydrolysis. Figure 1 (b) is aluminum nitride modified with oil and fat, and there is no obvious change after hydrolysis, indicating that the surface coating modification of the oil and fat of the present application can effectively inhibit the hydrolysis of aluminum nitride and improve the anti-hydrolysis ability of aluminum nitride.

[0066] This application also performed a morphology test on the resin composite material of Example 1 using a scanning electron microscope (SEM). Please refer to Figure 2 , Figure 2 to illustrate that the composite powder after the solid-phase reaction can be well dispersed in PTFE, forming a relatively uniform blend.

[0067] This application also performed the following performance parameter tests on the copper-clad laminates obtained in Example 1 and Comparative Examples 1-2: (1) Thermal conductivity test, and the test method refers to ASTM D5470.

[0068] (2) Coefficient of thermal expansion test, and the test method refers to IPC-TM-650 2.4.41.

[0069] (3) Dielectric constant and dielectric loss test, and the test method refers to the SPDR resonator method.

[0070] Please refer to Table 1 for the above test results.

[0071] Table 1. Test results of the performance parameters of the copper-clad laminates of Example 1 and Comparative Examples 1-2 of this application The preparation process of Example 1 of this application achieved high densification and chemical bonding of aluminum nitride and silica powder in the composite powder, reduced pores, thus effectively improving the dispersion and interfacial bonding between aluminum nitride and silica powder. Therefore, the problem of dielectric property weakening was effectively alleviated, and at the same time, the thermal properties of the composite powder were improved.

[0072] Compared with Example 1, Comparative Example 1 did not add aluminum nitride, and the obtained copper-clad laminate had poor thermal conductivity and a high coefficient of thermal expansion.

[0073] Compared with Example 1, in Comparative Example 2, the aluminum nitride added to the silica powder was not subjected to processes such as ball milling, pressing, coating, oil pressure, and solid-phase sintering. The solid-phase bonding between the silica powder and aluminum nitride in the composite powder was weak, the blend dispersion was poor, and partial hydrolysis of aluminum nitride occurred. The limited thermal conduction path that could be provided was further restricted. At the same time, the uniformity of the composite powder decreased, and the defects at the interface would cause an increase in the dielectric loss of the composite powder, and local stress might be introduced during the thermal expansion process.

[0074] The above embodiments are only used to illustrate the technical solutions of this application and not to limit them. Although this application has been described in detail with reference to the above preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of this application can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of this application.

Claims

1. A method for preparing a composite powder, characterized in that: The preparation method comprises: Ball-milling aluminum nitride and ceramic powder, wherein the ball-milling medium includes ethanol, and drying to obtain a first block-like solid; Pre-sintering the first block solid to obtain an intermediate; and After the intermediate is crushed and pressed, the intermediate is wrapped with a film layer having an insulating effect and processed under an oil press to obtain a second block solid; The second block solid is solid-phase sintered to obtain the composite powder.

2. The preparation method according to claim 1, characterized in that The preparation method further comprises: The pre-sintered product is subjected to the ball milling and the pre-sintering again to obtain the intermediate.

3. The preparation method according to claim 1, characterized in that: After the solid phase sintering, the preparation method further comprises: The solid-phase sintered product is sieved using a sieve having a mesh size of 500 to 5000.

4. The preparation method according to claim 1, characterized in that: After the solid phase sintering, the preparation method further comprises: A modifier is mixed with the solid phase sintered product, wherein the modifier includes oil, so that hydrophobic groups are grafted onto the surface of the solid phase sintered product to obtain the composite powder.

5. The preparation method according to claim 4, characterized in that: The preparation method also satisfies at least one of the following conditions: (1) The oil includes one or more of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β (aminoethyl)-γ-aminopropyltrimethoxysilane, N-β (aminoethyl)-γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl)-γ-aminopropyltriethoxysilane and N-β (aminoethyl)-γ-aminopropylmethyldiethoxysilane; (2) The mass ratio of the oil to the solid phase sintering product is 0.5% to 5%; (3) The modifier further includes water and ethanol, and the mass ratio of the water, the ethanol and the oil is 1:(1-3):(5-15).

6. The preparation method according to claim 1, characterized in that: The preparation method also satisfies at least one of the following conditions: (1) The pre-sintering temperature is 1000°C to 1200°C; (2) The pressure of the hydraulic press is 1 MPa to 2 MPa; (3) The temperature of the solid phase sintering is 1400°C to 1800°C.

7. A method for preparing a resin composite material, characterized in that: The preparation method comprises: preparing the composite powder obtained by the preparation method according to any one of claims 1 to 6 by co-coagulation with a resin material.

8. The preparation method according to claim 7, characterized in that: The co-coagulation includes mixing the dispersion of the composite powder and the colloidal resin material to obtain a mixed solution, and stirring the mixed solution to cause co-coagulation.

9. The preparation method according to claim 8, characterized in that: The preparation method further comprises filtering and drying the mixed solution after the co-coagulation to obtain the resin composite material.

10. A copper-clad laminate, comprising a copper foil layer and a dielectric layer stacked together, characterized in that: The dielectric layer satisfies at least one of the following conditions: (1) The dielectric layer comprises a resin material and a composite powder obtained by the preparation method according to any one of claims 1 to 6; (2) The dielectric layer comprises a resin composite material obtained by the preparation method according to any one of claims 7 to 9.

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