Preparation method of high-thermal-conductivity aluminum nitride tape casting green body and ceramic chip thereof

Abstract

The invention relates to the field of ceramic materials, in particular to a preparation method of a high-thermal-conductivity aluminum nitride tape-casting green body and a ceramic chip thereof, and the high-thermal-conductivity aluminum nitride tape-casting green body is prepared from the following raw materials in parts by weight: 100 parts of aluminum nitride powder, 1.5-3.5 parts of a dispersing agent, 8-12 parts of a binder, 3-6 parts of a plasticizer, 1-5 parts of a sintering aid and 80-100 parts of water. According to the invention, due to the low hydrolytic property of the slurry, the uniform distribution of the sintering aid and the optimized sintering schedule, the thermal conductivity of the obtained ceramic wafer is stabilized at 200W / (m.K) or above, the ceramic wafer has a uniform and compact microstructure, the bending strength can reach 450MPa or above, and the requirement of high-end application on mechanical reliability is met.

Description

Technical Field

[0001] This invention relates to the field of ceramic materials, specifically to a method for preparing a high thermal conductivity aluminum nitride cast green body and its ceramic sheets. Background Technology

[0002] Aluminum nitride ceramics possess high thermal conductivity, good insulation, low dielectric constant, low dielectric loss, a thermal expansion coefficient matching that of silicon, and good chemical stability. They are widely used in semiconductors and vacuum electronic fields, and are also key materials for electronic components in automotive electronics and aerospace. With the rapid development of electronic integration and packaging, electronic components and devices are trending towards miniaturization and micro-miniaturization. As an ideal electronic packaging and heat dissipation substrate material, aluminum nitride ceramics face higher performance requirements, necessitating further optimization and improvement of their fabrication processes. Casting is the mainstream process for producing its sheet-like products. However, existing aluminum nitride casting technologies have the following significant drawbacks: aluminum nitride powder is chemically reactive and readily reacts with moisture in solvents (especially water or organic solvent systems containing trace amounts of water), undergoing hydrolysis. This leads to a sharp increase in slurry viscosity and severely impairs the thermal conductivity of the final product. Summary of the Invention

[0003] Purpose of the invention: In view of the above-mentioned technical problems, the present invention proposes a method for preparing high thermal conductivity aluminum nitride cast green blanks and ceramic sheets thereof.

[0004] The technical solution adopted is as follows: A high thermal conductivity aluminum nitride cast green blank is made from the following raw materials in parts by weight: 100 parts aluminum nitride powder, 1.5-3.5 parts dispersant, 8-12 parts binder, 3-6 parts plasticizer, 1-5 parts sintering aid, and 80-100 parts water; The dispersant is made of alkenylimidazolium ionic liquid, vinylphosphonic acid, acrylic monomer and allyl polyoxyethylene ether.

[0005] Furthermore, the anion of the alkenyl imidazole ionic liquid is hexafluorophosphate. Hexafluorophosphate is highly stable in water and does not hydrolyze. Moreover, the larger volume of hexafluorophosphate provides stronger steric hindrance, allowing the polymer chains to be arranged more tightly on the surface of the aluminum nitride powder, further reducing the chance of water molecules contacting the aluminum nitride surface.

[0006] Furthermore, the acrylic monomer is composed of methacrylic acid and methyl methacrylate in a mass ratio of 3-5:1.

[0007] Furthermore, the dispersant is prepared as follows: Dissolve acrylic acid monomer and vinylphosphonic acid in water, adjust the pH to 7-8, and heat to 40-60℃. Then, dissolve alkenyl imidazole ionic liquid, allyl polyoxyethylene ether and initiator in water and add them dropwise to the reaction system. After the addition is complete, heat to 80-90℃, keep the temperature and stir the reaction. Then, precipitate the reaction solution in acetone, collect the product and dry it.

[0008] Furthermore, the mass ratio of the acrylic monomer, vinylphosphonic acid, alkenylimidazolium ionic liquid, and allyl polyoxyethylene ether is 4-6:1-2:0.5-1:1.5-2.5.

[0009] Furthermore, the adhesive is a compound of acrylic resin and polyvinyl butyral in a mass ratio of 2-5:1.

[0010] Acrylic resins provide high bond strength and toughness, while polyvinyl butyral provides excellent flexibility and film-forming properties. The combination of the two makes the green body both strong and tough.

[0011] Furthermore, the plasticizer is a compound of citrate ester plasticizer and polyethylene glycol in a mass ratio of 1:1-2.

[0012] The combination of these two materials results in high plasticizing efficiency, giving the green body excellent flexibility. It can be bent at large angles several times without breaking, greatly improving the yield of subsequent processing.

[0013] Furthermore, the sintering aid is composed of nano-yttrium oxide and nano-lanthanum oxide in a mass ratio of 3-5:1.

[0014] Nano-yttrium oxide and nano-lanthanum oxide possess larger specific surface areas and higher reactivity, enabling them to react more effectively with aluminum nitride, promoting rapid formation and uniform distribution of the liquid phase, thereby significantly reducing the sintering temperature. They also contribute to promoting uniform grain growth and refining grain size. The uniform and fine grain structure is beneficial for improving the mechanical strength and thermal conductivity of ceramics.

[0015] On the other hand, the preparation method of the above-mentioned high thermal conductivity aluminum nitride cast green blank is as follows: Aluminum nitride powder, sintering aid, dispersant and water are mixed and ball-milled to obtain a dispersion. After sealed aging, binder and plasticizer are added and ball-milled again to obtain a mixed slurry. The mixed slurry is then degassed under vacuum and filtered through a sieve to obtain a casting slurry. The casting slurry is then cast into a mold.

[0016] On the other hand, the present invention also provides a method for preparing ceramic sheets: After removing the binder from the high thermal conductivity aluminum nitride cast green body, it is then sintered at 1750-1850℃ under a flowing nitrogen atmosphere.

[0017] The beneficial effects of this invention are: The large amounts of organic solvents used in non-aqueous casting processes are detrimental to the green preparation of aluminum nitride ceramics, increase manufacturing costs, and raise safety and environmental concerns. Aqueous casting systems, on the other hand, use water as a solvent, offering advantages such as being pollution-free, environmentally friendly, non-flammable, and low-cost, making them suitable for the green and low-cost manufacturing of aluminum nitride ceramics. However, aluminum nitride powder readily undergoes hydrolysis with water, introducing additional oxygen elements onto the surface of the ceramic powder. After high-temperature sintering, this increases the oxygen content in the aluminum nitride ceramic lattice, leading to a decrease in the thermal conductivity and mechanical properties of aluminum nitride.

[0018] In the existing technology, in order to inhibit the hydrolysis of aluminum nitride, it is necessary to first use phosphoric acid to acid wash the aluminum nitride powder to form a water-insoluble phosphate protective layer on its surface, thereby inhibiting its reaction with water and improving its resistance to hydrolysis. However, this will generate a lot of acidic waste liquid and add an extra acid washing step, which is not conducive to industrial production.

[0019] This invention provides a dispersant made of alkenylimidazolium ionic liquid, vinylphosphonic acid, acrylic monomer, and allyl polyoxyethylene ether. The nitrogen atom of the imidazole ring in the alkenylimidazolium ionic liquid can serve as a coordination site, reacting with the Al atoms on the surface of aluminum nitride powder. 3+ Through coordination, a stable chelate structure is formed. The imidazolium cation can also electrostatically adsorb onto the surface of aluminum nitride and form a zwitterionic structure with the negative charge of phosphonic acid, thereby increasing the thickness of the electric double layer and maintaining the stability of the slurry.

[0020] Phosphonic acid groups can coordinate with Al on the surface of aluminum nitride powder via bidentate or tripentate coordination. 3+ The formation of a stable chelate ring structure effectively blocks direct contact between water molecules and aluminum nitride powder, inhibiting aluminum nitride hydrolysis. Furthermore, the hydrophobic nature of the polyethylene-based skeleton can form a physical barrier on the outside of the coordination layer, significantly reducing the adsorption and penetration of water molecules on the particle surface.

[0021] The carboxyl groups of methacrylic acid can be strongly adsorbed onto the surface of positively charged aluminum nitride particles, providing electrostatic anchoring. The polyoxyethylene chains of allyl polyoxyethylene ether form a hydration layer on the surface of aluminum nitride particles, preventing the aluminum nitride particles from getting close to each other through steric hindrance. It can also form hydrogen bonds with water molecules to enhance lubrication. Methyl methacrylate can enhance the rigidity of molecular chains, reduce self-entanglement, form a steric hindrance layer with a certain mechanical strength, and improve steric hindrance efficiency.

[0022] In this invention, the dispersant inhibits aluminum nitride hydrolysis, increases solid content, and maintains slurry stability, laying the foundation for subsequent casting and sintering. This meets the requirements for preparing high thermal conductivity aluminum nitride ceramics in an aqueous system, offering advantages such as being pollution-free, environmentally friendly, non-flammable, and low-cost. Thanks to the low hydrolytic activity of the slurry, the uniform distribution of the sintering aid, and the optimized sintering process, the resulting ceramic sheets exhibit a stable thermal conductivity above 200 W / (m·K), along with a uniform and dense microstructure and a flexural strength exceeding 450 MPa, meeting the mechanical reliability requirements of high-end applications. Detailed Implementation

[0023] Unless otherwise specified in the examples, the conditions were performed under standard conditions or as recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products. Techniques not mentioned in this invention refer to existing technologies. Unless otherwise specified, the following examples and comparative examples are parallel experiments, using the same processing steps and parameters.

[0024] Aluminum nitride powder: average particle size D50 is 0.8-1.5μm, from TOKUYAMA Chemical Co., Ltd., Japan.

[0025] Dispersant: Homemade.

[0026] Acrylic resins: Hanwha S-74 waterborne acrylic resin.

[0027] Polyvinyl butyral: Eastman Butvar PVB 63148-65-2 (USA).

[0028] Acetyl tributyl citrate: Shandong Kexing Chemical Co., Ltd.

[0029] Polyethylene glycol-2000: Shandong Kexing Chemical Co., Ltd.

[0030] Nano-yttrium oxide: Shanghai Hanlang New Materials Technology Co., Ltd.

[0031] Nano-lanthanum oxide: Shandong Mengxi New Materials Co., Ltd.

[0032] Example 1: A high thermal conductivity aluminum nitride cast green blank is made from the following raw materials in parts by weight: 100 parts aluminum nitride powder, 2.5 parts dispersant, 9 parts acrylic resin, 3 parts polyvinyl butyral, 2 parts acetyl tributyl citrate, 3 parts polyethylene glycol-2000, 4 parts nano yttrium oxide, 1 part nano lanthanum oxide, and 90 parts deionized water.

[0033] The dispersant is made of 1-allyl-3-methylimidazolium hexafluorophosphate, vinylphosphonic acid, acrylic monomer, and allyl polyoxyethylene ether. The acrylic monomer is composed of methacrylic acid and methyl methacrylate in a mass ratio of 4:1. The preparation method of the dispersant is as follows: Dissolve 40g methacrylic acid, 10g methyl methacrylate, and 15g vinylphosphonic acid in 500ml deionized water. Adjust the pH to 7-8 with 0.1M sodium hydroxide solution. Heat to 50℃. Dissolve 8g 1-allyl-3-methylimidazolium hexafluorophosphate, 20g allyl polyoxyethylene ether, and 0.5g initiator KPS in an appropriate amount of deionized water and add them dropwise to the reaction system. After the addition is complete, heat to 85℃ and stir for 4 hours. Finally, precipitate the reaction solution in acetone, collect the product, and vacuum dry it.

[0034] A method for preparing ceramic sheets: Aluminum nitride powder, nano-yttrium oxide, nano-lanthanum oxide, dispersant, and deionized water were added to a ball mill jar and mixed evenly. The mixture was ball-milled at 300 rpm for 60 min to obtain a dispersion. After sealing and aging for 24 h, acrylic resin, polyvinyl butyral, acetyl tributyl citrate, and polyethylene glycol-2000 were added. The mixture was then ball-milled at 500 rpm for 10 h to obtain a mixed slurry. The mixed slurry was vacuum degassed for 30 min and filtered through a 200-mesh sieve to obtain a cast slurry.

[0035] The casting slurry is injected into the casting machine hopper and cast on a polyester film carrier in a dry and clean air environment. The wet film thickness is controlled by the gap of the doctor blade. After casting, the film enters the drying channel and the drying temperature range is 30-60℃ to obtain a green body. The green body is placed in an atmosphere sintering furnace and heated from room temperature to 300℃ at a rate of 1℃ / min in flowing air and held for 60 min. Then, the temperature is increased to 600℃ at a rate of 0.5℃ / min and held for 120 min to completely remove the organic carrier. After debinding, the temperature is increased to 1800℃ at a rate of 10℃ / min in a flowing nitrogen atmosphere and held for sintering for 3 h. The film is then cooled in the furnace.

[0036] Example 2: A high thermal conductivity aluminum nitride cast green blank is made from the following raw materials in parts by weight: 100 parts aluminum nitride powder, 3.5 parts dispersant, 9 parts acrylic resin, 3 parts polyvinyl butyral, 2 parts acetyl tributyl citrate, 3 parts polyethylene glycol-2000, 4 parts nano yttrium oxide, 1 part nano lanthanum oxide, and 100 parts deionized water.

[0037] The dispersant is made of 1-allyl-3-methylimidazolium hexafluorophosphate, vinylphosphonic acid, acrylic monomer and allyl polyoxyethylene ether. The acrylic monomer is composed of methacrylic acid and methyl methacrylate in a mass ratio of 4:1. The preparation method of the dispersant is the same as in Example 1.

[0038] A method for preparing ceramic sheets: Aluminum nitride powder, nano-yttrium oxide, nano-lanthanum oxide, dispersant, and deionized water were added to a ball mill jar and mixed evenly. The mixture was ball-milled at 300 rpm for 60 min to obtain a dispersion. After sealing and aging for 24 h, acrylic resin, polyvinyl butyral, acetyl tributyl citrate, and polyethylene glycol-2000 were added. The mixture was then ball-milled at 500 rpm for 10 h to obtain a mixed slurry. The mixed slurry was vacuum degassed for 30 min and filtered through a 200-mesh sieve to obtain a cast slurry.

[0039] The casting slurry is injected into the casting machine hopper and cast on a polyester film carrier in a dry and clean air environment. The wet film thickness is controlled by the gap of the doctor blade. After casting, it enters the drying channel and the drying temperature range is 30-60℃ to obtain a green body. The green body is placed in an atmosphere sintering furnace and heated from room temperature to 300℃ at a rate of 1℃ / min in flowing air and held for 60 min. Then, the temperature is increased to 600℃ at a rate of 0.5℃ / min and held for 120 min to completely remove the organic carrier. After debinding, the temperature is increased to 1850℃ at a rate of 5℃ / min in a flowing nitrogen atmosphere and held for sintering for 2 h. It is then cooled with the furnace.

[0040] Example 3: A high thermal conductivity aluminum nitride cast green blank is made from the following raw materials in parts by weight: 100 parts aluminum nitride powder, 1.5 parts dispersant, 9 parts acrylic resin, 3 parts polyvinyl butyral, 2 parts acetyl tributyl citrate, 3 parts polyethylene glycol-2000, 4 parts nano yttrium oxide, 1 part nano lanthanum oxide, and 80 parts deionized water.

[0041] The dispersant is made of 1-allyl-3-methylimidazolium hexafluorophosphate, vinylphosphonic acid, acrylic monomer and allyl polyoxyethylene ether. The acrylic monomer is composed of methacrylic acid and methyl methacrylate in a mass ratio of 4:1. The preparation method of the dispersant is the same as in Example 1.

[0042] A method for preparing ceramic sheets: Aluminum nitride powder, nano-yttrium oxide, nano-lanthanum oxide, dispersant, and deionized water were added to a ball mill jar and mixed evenly. The mixture was ball-milled at 300 rpm for 60 min to obtain a dispersion. After sealing and aging for 24 h, acrylic resin, polyvinyl butyral, acetyl tributyl citrate, and polyethylene glycol-2000 were added. The mixture was then ball-milled at 500 rpm for 10 h to obtain a mixed slurry. The mixed slurry was vacuum degassed for 30 min and filtered through a 200-mesh sieve to obtain a cast slurry.

[0043] The casting slurry is injected into the casting machine hopper and cast onto a polyester film carrier in a dry, clean air environment. The wet film thickness is controlled by the gap between the doctor blades. After casting, the film enters the drying channel, where the drying temperature range is 30-60℃, resulting in a green body. The green body is then placed in an atmosphere sintering furnace and heated from room temperature to 300℃ at a rate of 1℃ / min in flowing air, and held for 60 minutes. The temperature is then increased to 600℃ at a rate of 0.2℃ / min and held for 120 minutes to completely remove the organic carrier. After debinding, the temperature is increased to 1750℃ at a rate of 10℃ / min in a flowing nitrogen atmosphere and held for sintering for 6 hours. The film is then cooled in the furnace.

[0044] Comparative Example 1: It is basically the same as Example 1, except that sodium hexametaphosphate is used instead of the self-made dispersant.

[0045] Comparative Example 2: It is basically the same as Comparative Example 1, except that ammonium polyacrylate is used instead of the homemade dispersant.

[0046] Comparative Example 3: It is basically the same as Comparative Example 1, except that 1-allyl-3-methylimidazolium chloride is used instead of 1-allyl-3-methylimidazolium hexafluorophosphate in the preparation of the dispersant.

[0047] The dispersant is made of 1-allyl-3-methylimidazolium chloride, vinylphosphonic acid, acrylic monomer, and allyl polyoxyethylene ether. The acrylic monomer is composed of methacrylic acid and methyl methacrylate in a mass ratio of 4:1. The preparation method of the dispersant is as follows: Dissolve 40g methacrylic acid, 10g methyl methacrylate, and 15g vinylphosphonic acid in 500ml deionized water. Adjust the pH to 7-8 with 0.1M sodium hydroxide solution. Heat to 50℃. Dissolve 8g 1-allyl-3-methylimidazolium chloride, 20g allyl polyoxyethylene ether, and 0.5g initiator KPS in an appropriate amount of deionized water and add them dropwise to the reaction system. After the addition is complete, heat to 85℃ and stir for 4 hours. Finally, precipitate the reaction solution in acetone, collect the product, and vacuum dry it.

[0048] Comparative Example 4: It is basically the same as Example 1, except that 1-allyl-3-methylimidazolium hexafluorophosphate is not added during the preparation of the dispersant.

[0049] The dispersant is made of vinylphosphonic acid, acrylic monomer, and allyl polyoxyethylene ether. The acrylic monomer is composed of methacrylic acid and methyl methacrylate in a mass ratio of 4:1. The preparation method of the dispersant is as follows: Dissolve 40g methacrylic acid, 10g methyl methacrylate, and 15g vinylphosphonic acid in 500ml deionized water. Adjust the pH to 7-8 with 0.1M sodium hydroxide solution. Heat to 50℃. Dissolve 20g allyl polyoxyethylene ether and 0.5g initiator KPS in an appropriate amount of deionized water and add them dropwise to the reaction system. After the addition is complete, heat to 85℃ and stir for 4 hours. Finally, precipitate the reaction solution in acetone, collect the product, and vacuum dry it.

[0050] Comparative Example 5: It is basically the same as Example 1, except that vinylphosphonic acid is not added during the preparation of the dispersant.

[0051] The dispersant is made of 1-allyl-3-methylimidazolium hexafluorophosphate, acrylic monomer, and allyl polyoxyethylene ether. The acrylic monomer is composed of methacrylic acid and methyl methacrylate in a mass ratio of 4:1. The preparation method of the dispersant is as follows: Dissolve 40g of methacrylic acid and 10g of methyl methacrylate in 500ml of deionized water. Adjust the pH to 7-8 with 0.1M sodium hydroxide solution. Heat to 50℃. Dissolve 8g of 1-allyl-3-methylimidazolium hexafluorophosphate, 20g of allyl polyoxyethylene ether, and 0.5g of initiator KPS in an appropriate amount of deionized water and add them dropwise to the reaction system. After the addition is complete, heat to 85℃ and stir for 4 hours. Finally, precipitate the reaction solution in acetone, collect the product, and vacuum dry it.

[0052] Comparative Example 6: It is basically the same as Example 1, except that acrylic acid monomers are not added during the preparation of the dispersant.

[0053] The dispersant is made of 1-allyl-3-methylimidazolium hexafluorophosphate, vinylphosphonic acid, and allyl polyoxyethylene ether, and the preparation method of the dispersant is as follows: Dissolve 15g of vinylphosphonic acid in 500ml of deionized water, adjust the pH to 7-8 with 0.1M sodium hydroxide solution, and heat to 50℃. Dissolve 8g of 1-allyl-3-methylimidazolium hexafluorophosphate, 20g of allyl polyoxyethylene ether, and 0.5g of initiator KPS in an appropriate amount of deionized water and add them dropwise to the reaction system. After the addition is complete, heat to 85℃ and stir for 4 hours. Finally, precipitate the reaction solution in acetone, collect the product, and vacuum dry it.

[0054] Comparative Example 7: It is basically the same as Example 1, except that allyl polyoxyethylene ether is not added during the preparation of the dispersant.

[0055] The dispersant is made from 1-allyl-3-methylimidazolium hexafluorophosphate, vinylphosphonic acid, and acrylic acid monomers. The acrylic acid monomers are composed of methacrylic acid and methyl methacrylate in a mass ratio of 4:1. The preparation method of the dispersant is as follows: Dissolve 40g methacrylic acid, 10g methyl methacrylate, and 15g vinylphosphonic acid in 500ml deionized water. Adjust the pH to 7-8 with 0.1M sodium hydroxide solution. Heat to 50℃. Dissolve 8g 1-allyl-3-methylimidazolium hexafluorophosphate and 0.5g initiator KPS in an appropriate amount of deionized water and add them dropwise to the reaction system. After the addition is complete, heat to 85℃ and stir for 4 hours. Finally, precipitate the reaction solution in acetone, collect the product, and vacuum dry it.

[0056] Performance testing The ceramic sheets prepared in Examples 1-3 and Comparative Examples 1-7 were used as samples for performance testing.

[0057] Thermal conductivity was determined using the transient plane heat source method, and flexural strength was obtained by referring to the test method for flexural strength of ceramic materials in GB / T 4741-1999.

[0058] The test results are shown in Table 1 below: As shown in Table 1 above, the ceramic sheet prepared by this invention not only has good thermal conductivity, but also excellent mechanical properties.

[0059] A comparison of the data from Example 1 and Comparative Examples 1-2 shows that, compared with conventional dispersants, the dispersant of the present invention can effectively improve the thermal conductivity and mechanical properties of ceramic sheets.

[0060] A comparison of the data from Example 1 and Comparative Example 3 shows that the addition of 1-allyl-3-methylimidazolium chloride has a greater effect on improving the thermal conductivity and mechanical properties of the ceramic sheet than that of 1-allyl-3-methylimidazolium chloride.

[0061] A comparison of the data from Example 1 with Comparative Examples 4-7 shows that the addition of 1-allyl-3-methylimidazolium hexafluorophosphate, vinylphosphonic acid, acrylic monomer, and allyl polyoxyethylene ether during the preparation of the dispersant all play a positive role in improving the thermal conductivity and mechanical properties of the ceramic sheet.

[0062] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high thermal conductivity aluminum nitride cast green billet, characterized in that, Made from the following parts by weight of raw materials: 100 parts aluminum nitride powder, 1.5-3.5 parts dispersant, 8-12 parts binder, 3-6 parts plasticizer, 1-5 parts sintering aid, and 80-100 parts water; The dispersant is made of alkenylimidazolium ionic liquid, vinylphosphonic acid, acrylic monomer and allyl polyoxyethylene ether.

2. The high thermal conductivity aluminum nitride cast green blank as described in claim 1, characterized in that, The anion of the alkenylimidazolium ionic liquid is hexafluorophosphate.

3. The high thermal conductivity aluminum nitride cast green blank as described in claim 1, characterized in that, The acrylic monomer is a compound of methacrylic acid and methyl methacrylate in a mass ratio of 3-5:

1.

4. The high thermal conductivity aluminum nitride cast green blank as described in claim 3, characterized in that, The dispersant is prepared as follows: Dissolve acrylic acid monomer and vinylphosphonic acid in water, adjust the pH to 7-8, and heat to 40-60℃. Then, dissolve alkenyl imidazole ionic liquid, allyl polyoxyethylene ether and initiator in water and add them dropwise to the reaction system. After the addition is complete, heat to 80-90℃, keep the temperature and stir the reaction. Then, precipitate the reaction solution in acetone, collect the product and dry it.

5. The high thermal conductivity aluminum nitride cast green blank as described in claim 4, characterized in that, The mass ratio of the acrylic monomer, vinylphosphonic acid, alkenyl imidazole ionic liquid and allyl polyoxyethylene ether is 4-6:1-2:0.5-1:1.5-2.

5.

6. The high thermal conductivity aluminum nitride cast green blank as described in claim 1, characterized in that, The adhesive is a compound of acrylic resin and polyvinyl butyral in a mass ratio of 2-5:

1.

7. The high thermal conductivity aluminum nitride cast green blank as described in claim 1, characterized in that, The plasticizer is a compound of citrate ester plasticizer and polyethylene glycol in a mass ratio of 1:1-2.

8. The high thermal conductivity aluminum nitride cast green blank as described in claim 1, characterized in that, The sintering aid is composed of nano-yttrium oxide and nano-lanthanum oxide in a mass ratio of 3-5:

1.

9. The high thermal conductivity aluminum nitride cast green blank as described in claim 1, characterized in that, Its preparation method is as follows: Aluminum nitride powder, sintering aid, dispersant and water are mixed and ball-milled to obtain a dispersion. After sealed aging, binder and plasticizer are added and ball-milled again to obtain a mixed slurry. The mixed slurry is then degassed under vacuum and filtered through a sieve to obtain a casting slurry. The casting slurry is then cast into a mold.

10. A method for preparing a ceramic sheet, characterized in that, The high thermal conductivity aluminum nitride cast green blank according to any one of claims 1-9 is debonded and then sintered at 1750-1850°C under a flowing nitrogen atmosphere.

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