Aluminum nitride substrate with high heat dissipation and light weight and preparation method thereof

Abstract

This invention discloses a high-heat-dissipation, lightweight aluminum nitride substrate and its preparation method, belonging to the field of aluminum nitride substrate preparation technology. The preparation method of the high-heat-dissipation, lightweight aluminum nitride substrate includes the following steps: Step 1: Mixing aluminum nitride powder with a modified dispersant to obtain modified aluminum nitride powder, then further mixing with a composite sintering aid and ball milling to obtain a pretreated mixed powder; Step 2: Mixing the pretreated mixed powder, binder, plasticizer, and ethanol, ball milling, and post-treatment to obtain a green body; Step 3: Sintering and treating the green body to obtain the high-heat-dissipation, lightweight aluminum nitride substrate. The aluminum nitride substrate prepared by this method has high heat dissipation performance, high density, and excellent lightweight properties.

Description

Technical Field

[0001] This invention belongs to the field of aluminum nitride substrate preparation technology, specifically relating to a high heat dissipation and lightweight aluminum nitride substrate and its preparation method. Background Technology

[0002] With the rapid development of electronic information technology towards high integration and high power density, thermal management of chips and devices has become a core bottleneck restricting system performance and reliability. Traditional heat dissipation materials, such as alumina ceramics and copper substrates, are insufficient in thermal conductivity or excessively dense, making it difficult to meet the dual requirements of efficient heat dissipation and lightweight design for next-generation electronic devices. Against this backdrop, aluminum nitride ceramic substrates, with their unique physicochemical properties, are gradually becoming a key material in the field of high-end electronic packaging. Their thermal conductivity far exceeds that of alumina ceramics, enabling rapid transfer of heat generated by the chip to the heat dissipation structure, effectively avoiding performance degradation and shortened lifespan caused by localized overheating. Simultaneously, the coefficient of thermal expansion of aluminum nitride is highly compatible with that of silicon chips, significantly reducing the risk of interface failure caused by thermal stress and improving the stability of devices in extreme environments.

[0003] Lightweight design is another significant advantage of aluminum nitride substrates. Compared to metals such as copper, aluminum nitride has a lower density. In weight-sensitive fields such as aerospace and new energy vehicles, its weight reduction effect can be directly translated into reduced energy consumption and increased battery life. In addition, aluminum nitride has excellent electrical insulation, corrosion resistance, and high-frequency signal transmission characteristics, which can meet the stringent requirements of low loss and high reliability in scenarios such as 5G communication and artificial intelligence.

[0004] Patent CN118495961A discloses a composite aluminum nitride substrate, its preparation method, and its applications. The preparation method includes the following steps: preparing modified diamond whiskers with inorganic-philic groups on their surface; mixing the modified diamond whiskers with aluminum nitride powder to form a mixed powder; pressing the mixed powder into a green blank; and sintering the green blank to obtain the composite aluminum nitride substrate. By doping modified diamond whiskers between aluminum nitride particles and forming a three-dimensional network structure between the aluminum nitride particles, the resulting composite aluminum nitride substrate possesses excellent thermal conductivity, as well as outstanding mechanical strength and bending resistance, making it an ideal material for heat dissipation in high-power electronic devices. Although this composite aluminum nitride substrate, through the formation of a three-dimensional network structure by doping with modified diamond whiskers, exhibits excellent thermal conductivity, mechanical strength, and bending resistance, there is still room for improvement in terms of heat dissipation and lightweighting. In terms of heat dissipation, although the three-dimensional network structure is beneficial to heat conduction, there is still room for optimization in the uniformity of the mixture of modified diamond whiskers and aluminum nitride powder, as well as the tightness of the interface between the two. This will affect the heat transfer efficiency. In terms of lightweighting, the modified diamond whiskers and aluminum nitride powder themselves have a large density, and in order to ensure performance, it is difficult to further reduce the overall density of the material under the current formulation and preparation process, which limits the development of lightweighting. Summary of the Invention

[0005] The purpose of this invention is to provide a lightweight aluminum nitride substrate with high heat dissipation and a method for preparing the same, in order to solve the technical problems of poor lightweighting and heat dissipation performance of aluminum nitride substrates in the prior art.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] This invention provides a method for preparing a high-heat-dissipation and lightweight aluminum nitride substrate, comprising the following steps:

[0008] Step 1: Add aluminum nitride powder to ethanol, then add a modified dispersant and mix to obtain modified aluminum nitride powder; mix the modified aluminum nitride powder with a composite sintering aid and ball mill to obtain a pretreated mixed powder;

[0009] Step 2: Add the pretreated mixed powder to a container containing binder, plasticizer and ethanol, ball mill, vacuum degas to obtain slurry, then coat the slurry onto the carrier, dry to obtain blank, cut, stack, laminate, remove glue to obtain blank;

[0010] Step 3: Place the blank into the sintering furnace, evacuate and heat it, then introduce nitrogen gas and continue to heat and hold it. After the treatment is completed, cool it and depressurize it to obtain the sintered substrate. Then place it in the working chamber, evacuate it, and react it under high temperature and high pressure in an argon atmosphere. After the reaction is completed, cool it, grind it and polish it to obtain a high heat dissipation and lightweight aluminum nitride substrate.

[0011] Preferably, in step one, the aluminum nitride powder has a purity > 99.5%, an oxygen content < 0.5%, a particle size < 3 μm, and the ratio of aluminum nitride powder, ethanol, modified dispersant, and composite sintering aid is (80-90) g : (50-75) mL : (2-5) g : (2.4-10) g, and the ball milling time is 8-12 h.

[0012] Preferably, the method for preparing the modified dispersant includes the following steps:

[0013] Q1: Add methyl allyl polyoxyethylene ether and mercaptoacetic acid to a container containing deionized water, heat, add ammonium persulfate aqueous solution dropwise, then add acrylic acid aqueous solution dropwise, and then add methanol solution containing methacryloyloxypropyltrimethoxysilane dropwise. After the addition is complete, react. After the reaction is complete, cool down, add sodium hydroxide aqueous solution, and rotary evaporate to obtain a mixture.

[0014] Q2: Wash the dialysis bag with distilled water, then add the mixture into the dialysis bag, place it in deionized water, and dialyze it on a magnetic stirrer. After dialysis, freeze-crystallize and freeze-dry to obtain the modified dispersant.

[0015] The synthesis reaction formula for the modified dispersant in the above process is as follows:

[0016]

[0017] Preferably, in Q1, the molar ratio of methyl allyl polyoxyethylene ether, acrylic acid, and methacryloyloxypropyltrimethoxysilane is (0.8-1.1):(0.88-1.16):(0.12-0.16), the average molecular weight of methyl allyl polyoxyethylene ether is 1000, the temperature is raised to 50-55℃, the reaction time is 3-4h, and a 30wt% sodium hydroxide aqueous solution is added to adjust the pH of the reaction system to 7-7.2.

[0018] Preferably, in Q2, the molecular weight interception of the dialysis bag is 2000. During the dialysis process, the deionized water is changed every 2 hours. Once the color of the deionized water becomes lighter, the deionized water is changed to be changed every 12 hours.

[0019] Preferably, the preparation method of the composite sintering aid includes the following steps:

[0020] S1: Add distilled water to a container, then add concentrated nitric acid, mix well, then add barium nitrate, cerium oxide, zirconium oxynitrate, yttrium nitrate hexahydrate and nickel nitrate in sequence, stir and mix, then add citric acid, then add ammonia to adjust the pH, stir the reaction, and heat to obtain the sintering aid precursor;

[0021] S2: Add the sintering aid precursor into a muffle furnace and calcine to obtain a composite sintering aid.

[0022] In the above process, under acidic conditions, citric acid undergoes a complexation reaction with metal ions to form a stable water-soluble complex, thereby achieving a high degree of uniform mixing of the components at the molecular level. Subsequently, by adding ammonia to adjust the pH, the formation of the metal-citric acid complex is further promoted. During the heating and final calcination stages, nitrate ions and citric acid undergo a vigorous redox reaction, releasing a large amount of gas and heat, which causes the sintering aid precursor to rapidly decompose into a composite sintering aid.

[0023] Preferably, in S1, the molar ratio of barium nitrate, cerium oxide, zirconium oxynitrate, yttrium nitrate hexahydrate, nickel nitrate, and citric acid is (0.88-1.21):(0.21-0.63):(0.22-0.61):(0.05-0.26):(0.01-0.08):(3.81-4.19), the pH is adjusted to 7-9, and the stirring reaction time is 6-8 h; in S2, the calcination temperature is 1000-1200℃, and the calcination time is 6-8 h.

[0024] Preferably, in step two, the adhesive is composed of one or more of polyvinyl butyral, butyl acrylate, polyvinyl alcohol, and polyvinylpyrrolidone, and the plasticizer is composed of one or more of dibutyl phthalate, glycerol, polyethylene glycol, diethylene glycol diisooctanoate, and butyl benzyl phthalate. The heating rate during the glue removal process is 0.2-2℃ / min, and the temperature is raised to 550-600℃ and kept at that temperature for 1-3 hours under nitrogen atmosphere.

[0025] Preferably, in step three, the vacuum is evacuated to 10... -2 -10 -3 The temperature is raised to 800-1200℃, nitrogen is introduced, and the temperature is raised to 1700-1800℃ at a rate of 5-10℃ / min. The temperature is held for 2-6 hours, and then cooled to 550-590℃ at a rate of 3-5℃ / min. The high temperature is 1400-1600℃, the high pressure is 100-200MPa, and the reaction time is 1-3 hours.

[0026] A lightweight aluminum nitride substrate with high heat dissipation was prepared using the above-described preparation method.

[0027] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0028] 1. In the process of preparing aluminum nitride substrates, the present invention utilizes pressureless sintering and hot isostatic pressing (HIP) to synergistically enhance the material properties. During sintering, the precise control of atmosphere and temperature effectively removes impurities and gases from the blank, achieving preliminary grain boundary purification. After pressureless sintering, the closed pores inside the material are eliminated by the HIP process, completely eliminating the closed pores and achieving high densification.

[0029] 2. This invention applies the modified dispersant obtained to the preparation process of aluminum nitride substrates, which can effectively prevent the agglomeration of aluminum nitride powder in the slurry, laying the foundation for the preparation of high-density, uniformly structured substrates. The polyether long chains contained in the modified dispersant fully extend in the aqueous medium to form a hydration layer, generating a strong steric hindrance effect between particles, preventing particles from agglomerating due to van der Waals forces. The carboxylate ions generated by the ionization of the modified dispersant molecules are adsorbed on the surface of the aluminum nitride powder, enhancing the dispersion stability through electrostatic repulsion between particles. At the same time, the silanoxy groups at the ends of the modified dispersant form hydrogen bonds or partial covalent bonds with the hydroxyl groups on the surface of the aluminum nitride powder through hydrolysis, strengthening adsorption and making it difficult to desorb, thereby significantly improving the dispersibility and stability of the aluminum nitride powder, resulting in the final aluminum nitride substrate with excellent density and higher thermal conductivity.

[0030] 3. This invention applies the prepared composite sintering aid to the preparation process of aluminum nitride substrates, which can effectively promote the density of the substrate and improve its thermal conductivity. The components in the composite sintering aid react with the primary alumina on the surface of the aluminum nitride particles to form a liquid phase with a low eutectic point and low viscosity. Subsequently, this substance greatly promotes particle rearrangement and mass transport through a dissolution-precipitation mechanism, achieving rapid densification at a lower temperature. At the same time, the composite sintering aid reacts with oxygen impurities to generate a stable grain boundary phase, purifying the aluminum nitride lattice and significantly reducing the defect concentration of phonon scattering. Then, through the sintering process, the grain boundary phase gathers at the grain boundaries, forming a continuous thermally conductive network composed of high-purity aluminum nitride grains, giving the prepared aluminum nitride substrate excellent thermal conductivity. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Example 1: This example discloses a method for preparing a modified dispersant, including the following steps:

[0033] Q1: Add 9.5g of methyl allyl polyoxyethylene ether with an average molecular weight of 1000 and 0.19g of mercaptoacetic acid to a container containing 100mL of deionized water, heat to 50℃, add 1mL of ammonium persulfate aqueous solution with a concentration of 0.1425g / mL, then add 2mL of acrylic acid aqueous solution with a concentration of 0.367g / mL, and then add 2mL of methanol solution containing 0.348g of methacryloyloxypropyltrimethoxysilane. After the addition is complete, react for 4h. After the reaction is complete, cool down, add 30wt% sodium hydroxide aqueous solution to adjust the pH of the reaction system to 7, and rotary evaporate to obtain a mixture.

[0034] Q2: Wash the dialysis bag with distilled water. The molecular weight cutoff of the dialysis bag is 2000. Then add the mixture into the dialysis bag, place it in deionized water, and dialyze it on a magnetic stirrer. During the dialysis process, change the deionized water every 2 hours. When the color of the deionized water becomes lighter, change the deionized water every 12 hours. After the dialysis is completed, freeze crystallize and freeze dry to obtain the modified dispersant.

[0035] This embodiment discloses a method for preparing a composite sintering aid, including the following steps:

[0036] S1: Add 50 mL of distilled water to a container, then add 12 mL of 98 vt% concentrated nitric acid. After mixing well, add 1.3655 g of barium nitrate, 0.3615 g of cerium oxide, 0.4795 g of zirconium oxynitrate, 0.297 g of yttrium nitrate hexahydrate, and 0.0411 g of nickel nitrate in sequence. After stirring and mixing, add 3.84 g of citric acid, then add ammonia water to adjust the pH to 7. After stirring and reacting for 8 hours, heat to obtain the sintering aid precursor.

[0037] S2: Add the sintering aid precursor into a muffle furnace and calcine at 1100℃ for 8 hours to obtain a composite sintering aid.

[0038] This embodiment discloses a method for preparing a high-heat-dissipation and lightweight aluminum nitride substrate, including the following steps:

[0039] Step 1: Add 85g of aluminum nitride powder (purity > 99.5%, oxygen content < 0.5%, particle size < 3μm) to 62.5mL of ethanol, then add 3.5g of modified dispersant and mix to obtain modified aluminum nitride powder; mix the modified aluminum nitride powder with 6.2g of composite sintering aid and ball mill for 10h to obtain pretreated mixed powder;

[0040] Step 2: Add 8g of pretreated mixed powder to a container containing 0.11g of polyvinyl butyral, 0.14g of dibutyl phthalate and 10mL of ethanol, ball mill, vacuum degas, and obtain a slurry. Then coat the slurry onto a carrier, dry, and obtain a green sheet. Cut, stack, laminate, and remove the glue. The heating rate during the glue removal process is 1℃ / min. Heat to 550℃ and hold for 2h under nitrogen atmosphere to obtain a green body.

[0041] Step 3: Place the billet into the sintering furnace and evacuate it to 10°C. -2 After Pa, the temperature is raised to 1000℃, then nitrogen gas is introduced, and the temperature is raised to 1800℃ at a heating rate of 5℃ / min and held for 6 hours. After the treatment, the temperature is cooled to 550℃ at a cooling rate of 3℃ / min, and the pressure is released to obtain the sintered substrate. Then it is placed in the working chamber, vacuumed, and reacted at 1600℃ high temperature, 200MPa high pressure, and argon atmosphere for 3 hours. After the reaction, it is cooled, ground, and polished to obtain a high heat dissipation and lightweight aluminum nitride substrate.

[0042] Example 2: This example discloses a method for preparing a modified dispersant, including the following steps:

[0043] Q1: Add 8g of methyl allyl polyoxyethylene ether with an average molecular weight of 1000 and 0.19g of mercaptoacetic acid to a container containing 100mL of deionized water, heat to 50℃, add 1mL of ammonium persulfate aqueous solution with a concentration of 0.1425g / mL, then add 2mL of acrylic acid aqueous solution with a concentration of 0.317g / mL, and then add 2mL of methanol solution containing 0.298g of methacryloyloxypropyltrimethoxysilane. After the addition is complete, react for 4h. After the reaction is complete, cool down, add 30wt% sodium hydroxide aqueous solution to adjust the pH of the reaction system to 7, and rotary evaporate to obtain a mixture.

[0044] Q2: Wash the dialysis bag with distilled water. The molecular weight cutoff of the dialysis bag is 2000. Then add the mixture into the dialysis bag, place it in deionized water, and dialyze it on a magnetic stirrer. During the dialysis process, change the deionized water every 2 hours. When the color of the deionized water becomes lighter, change the deionized water every 12 hours. After the dialysis is completed, freeze crystallize and freeze dry to obtain the modified dispersant.

[0045] This embodiment discloses a method for preparing a composite sintering aid, including the following steps:

[0046] S1: Add 50 mL of distilled water to a container, then add 12 mL of 98 vt% concentrated nitric acid. After mixing well, add 1.1499 g of barium nitrate, 0.181 g of cerium oxide, 0.254 g of zirconium oxynitrate, 0.096 g of yttrium nitrate hexahydrate, and 0.0091 g of nickel nitrate in sequence. After stirring and mixing, add 3.66 g of citric acid, then add ammonia water to adjust the pH to 7. After stirring and reacting for 8 hours, heat to obtain the sintering aid precursor.

[0047] S2: Add the sintering aid precursor into a muffle furnace and calcine at 1100℃ for 8 hours to obtain a composite sintering aid.

[0048] This embodiment discloses a method for preparing a high-heat-dissipation and lightweight aluminum nitride substrate, including the following steps:

[0049] Step 1: Add 80g of aluminum nitride powder (purity > 99.5%, oxygen content < 0.5%, particle size < 3μm) to 50mL of ethanol, then add 2g of modified dispersant and mix to obtain modified aluminum nitride powder; mix the modified aluminum nitride powder with 2.4g of composite sintering aid and ball mill for 10h to obtain pretreated mixed powder;

[0050] Step 2: Add 8g of pretreated mixed powder to a container containing 0.11g of polyvinyl butyral, 0.14g of dibutyl phthalate and 10mL of ethanol, ball mill, vacuum degas, and obtain a slurry. Then coat the slurry onto a carrier, dry, and obtain a green sheet. Cut, stack, laminate, and remove the glue. The heating rate during the glue removal process is 1℃ / min. Heat to 550℃ and hold for 2h under nitrogen atmosphere to obtain a green body.

[0051] Step 3: Place the billet into the sintering furnace and evacuate it to 10°C. -2 After Pa, the temperature is raised to 1000℃, then nitrogen gas is introduced, and the temperature is raised to 1800℃ at a heating rate of 5℃ / min and held for 6 hours. After the treatment, the temperature is cooled to 550℃ at a cooling rate of 3℃ / min, and the pressure is released to obtain the sintered substrate. Then it is placed in the working chamber, vacuumed, and reacted at 1600℃ high temperature, 200MPa high pressure, and argon atmosphere for 3 hours. After the reaction, it is cooled, ground, and polished to obtain a high heat dissipation and lightweight aluminum nitride substrate.

[0052] Example 3: This example discloses a method for preparing a modified dispersant, including the following steps:

[0053] Q1: 11g of methyl allyl polyoxyethylene ether with an average molecular weight of 1000 and 0.19g of mercaptoacetic acid were added to a container containing 100mL of deionized water. The temperature was raised to 50℃, and 1mL of ammonium persulfate aqueous solution with a concentration of 0.1425g / mL was added dropwise. Then, 2mL of acrylic acid aqueous solution with a concentration of 0.418g / mL was added dropwise. Then, 2mL of methanol solution containing 0.397g of methacryloyloxypropyltrimethoxysilane was added dropwise. After the addition was completed, the reaction was allowed to proceed for 4 hours. After the reaction was completed, the temperature was lowered, and 30wt% sodium hydroxide aqueous solution was added to adjust the pH of the reaction system to 7. The mixture was then obtained by rotary evaporation.

[0054] Q2: Wash the dialysis bag with distilled water. The molecular weight cutoff of the dialysis bag is 2000. Then add the mixture into the dialysis bag, place it in deionized water, and dialyze it on a magnetic stirrer. During the dialysis process, change the deionized water every 2 hours. When the color of the deionized water becomes lighter, change the deionized water every 12 hours. After the dialysis is completed, freeze crystallize and freeze dry to obtain the modified dispersant.

[0055] This embodiment discloses a method for preparing a composite sintering aid, including the following steps:

[0056] S1: Add 50 mL of distilled water to a container, then add 12 mL of 98 vt% concentrated nitric acid. After mixing well, add 1.5811 g of barium nitrate, 0.542 g of cerium oxide, 0.705 g of zirconium oxynitrate, 0.498 g of yttrium nitrate hexahydrate and 0.0721 g of nickel nitrate in sequence. After stirring and mixing, add 4.02 g of citric acid, then add ammonia water to adjust the pH to 7. Stir and react for 8 hours, then heat to obtain the sintering aid precursor.

[0057] S2: Add the sintering aid precursor into a muffle furnace and calcine at 1100℃ for 8 hours to obtain a composite sintering aid.

[0058] This embodiment discloses a method for preparing a high-heat-dissipation and lightweight aluminum nitride substrate, including the following steps:

[0059] Step 1: Add 90g of aluminum nitride powder (purity > 99.5%, oxygen content < 0.5%, particle size < 3μm) to 75mL of ethanol, then add 5g of modified dispersant and mix to obtain modified aluminum nitride powder; mix the modified aluminum nitride powder with 10g of composite sintering aid and ball mill for 10h to obtain pretreated mixed powder;

[0060] Step 2: Add 8g of pretreated mixed powder to a container containing 0.11g of polyvinyl butyral, 0.14g of dibutyl phthalate and 10mL of ethanol, ball mill, vacuum degas, and obtain a slurry. Then coat the slurry onto a carrier, dry, and obtain a green sheet. Cut, stack, laminate, and remove the glue. The heating rate during the glue removal process is 1℃ / min. Heat to 550℃ and hold for 2h under nitrogen atmosphere to obtain a green body.

[0061] Step 3: Place the billet into the sintering furnace and evacuate it to 10°C. -2 After Pa, the temperature is raised to 1000℃, then nitrogen gas is introduced, and the temperature is raised to 1800℃ at a heating rate of 5℃ / min and held for 6 hours. After the treatment, the temperature is cooled to 550℃ at a cooling rate of 3℃ / min, and the pressure is released to obtain the sintered substrate. Then it is placed in the working chamber, vacuumed, and reacted at 1600℃ high temperature, 200MPa high pressure, and argon atmosphere for 3 hours. After the reaction, it is cooled, ground, and polished to obtain a high heat dissipation and lightweight aluminum nitride substrate.

[0062] Example 4: This example discloses a method for preparing a modified dispersant, including the following steps:

[0063] Q1: Add 9g of methyl allyl polyoxyethylene ether with an average molecular weight of 1000 and 0.19g of mercaptoacetic acid to a container containing 100mL of deionized water, heat to 50℃, add 1mL of ammonium persulfate aqueous solution with a concentration of 0.1425g / mL, then add 2mL of acrylic acid aqueous solution with a concentration of 0.343g / mL, and then add 2mL of methanol solution containing 0.321g of methacryloyloxypropyltrimethoxysilane. After the addition is complete, react for 4h. After the reaction is complete, cool down, add 30wt% sodium hydroxide aqueous solution to adjust the pH of the reaction system to 7, and rotary evaporate to obtain a mixture.

[0064] Q2: Wash the dialysis bag with distilled water. The molecular weight cutoff of the dialysis bag is 2000. Then add the mixture into the dialysis bag, place it in deionized water, and dialyze it on a magnetic stirrer. During the dialysis process, change the deionized water every 2 hours. When the color of the deionized water becomes lighter, change the deionized water every 12 hours. After the dialysis is completed, freeze crystallize and freeze dry to obtain the modified dispersant.

[0065] This embodiment discloses a method for preparing a composite sintering aid, including the following steps:

[0066] S1: Add 50 mL of distilled water to a container, then add 12 mL of 98 vt% concentrated nitric acid. After mixing well, add 1.4287 g of barium nitrate, 0.221 g of cerium oxide, 0.381 g of zirconium oxynitrate, 0.127 g of yttrium nitrate hexahydrate and 0.0628 g of nickel nitrate in sequence. After stirring and mixing, add 3.72 g of citric acid, then add ammonia water to adjust the pH to 7. After stirring and reacting for 8 hours, heat to obtain the sintering aid precursor.

[0067] S2: Add the sintering aid precursor into a muffle furnace and calcine at 1100℃ for 8 hours to obtain a composite sintering aid.

[0068] This embodiment discloses a method for preparing a high-heat-dissipation and lightweight aluminum nitride substrate, including the following steps:

[0069] Step 1: Add 82g of aluminum nitride powder (purity > 99.5%, oxygen content < 0.5%, particle size < 3μm) to 55mL of ethanol, then add 3g of modified dispersant and mix to obtain modified aluminum nitride powder; mix the modified aluminum nitride powder with 3.8g of composite sintering aid and ball mill for 10h to obtain pretreated mixed powder;

[0070] Step 2: Add 8g of pretreated mixed powder to a container containing 0.11g of polyvinyl butyral, 0.14g of dibutyl phthalate and 10mL of ethanol, ball mill, vacuum degas, and obtain a slurry. Then coat the slurry onto a carrier, dry, and obtain a green sheet. Cut, stack, laminate, and remove the glue. The heating rate during the glue removal process is 1℃ / min. Heat to 550℃ and hold for 2h under nitrogen atmosphere to obtain a green body.

[0071] Step 3: Place the billet into the sintering furnace and evacuate it to 10°C. -2 After Pa, the temperature is raised to 1000℃, then nitrogen gas is introduced, and the temperature is raised to 1800℃ at a heating rate of 5℃ / min and held for 6 hours. After the treatment, the temperature is cooled to 550℃ at a cooling rate of 3℃ / min, and the pressure is released to obtain the sintered substrate. Then it is placed in the working chamber, vacuumed, and reacted at 1600℃ high temperature, 200MPa high pressure, and argon atmosphere for 3 hours. After the reaction, it is cooled, ground, and polished to obtain a high heat dissipation and lightweight aluminum nitride substrate.

[0072] Example 5: This example discloses a method for preparing a modified dispersant, including the following steps:

[0073] Q1: Add 10g of methyl allyl polyoxyethylene ether with an average molecular weight of 1000 and 0.19g of mercaptoacetic acid to a container containing 100mL of deionized water, heat to 50℃, add 1mL of ammonium persulfate aqueous solution with a concentration of 0.1425g / mL, then add 2mL of acrylic acid aqueous solution with a concentration of 0.393g / mL, and then add 2mL of methanol solution containing 0.378g of methacryloyloxypropyltrimethoxysilane. After the addition is complete, react for 4h. After the reaction is complete, cool down, add 30wt% sodium hydroxide aqueous solution to adjust the pH of the reaction system to 7, and rotary evaporate to obtain a mixture.

[0074] Q2: Wash the dialysis bag with distilled water. The molecular weight cutoff of the dialysis bag is 2000. Then add the mixture into the dialysis bag, place it in deionized water, and dialyze it on a magnetic stirrer. During the dialysis process, change the deionized water every 2 hours. When the color of the deionized water becomes lighter, change the deionized water every 12 hours. After the dialysis is completed, freeze crystallize and freeze dry to obtain the modified dispersant.

[0075] This embodiment discloses a method for preparing a composite sintering aid, including the following steps:

[0076] S1: Add 50 mL of distilled water to a container, then add 12 mL of 98 vt% concentrated nitric acid. After mixing well, add 1.2117 g of barium nitrate, 0.412 g of cerium oxide, 0.621 g of zirconium oxynitrate, 0.387 g of yttrium nitrate hexahydrate and 0.0873 g of nickel nitrate in sequence. After stirring and mixing, add 3.97 g of citric acid, then add ammonia water to adjust the pH to 7. After stirring and reacting for 8 hours, heat to obtain the sintering aid precursor.

[0077] S2: Add the sintering aid precursor into a muffle furnace and calcine at 1100℃ for 8 hours to obtain a composite sintering aid.

[0078] This embodiment discloses a method for preparing a high-heat-dissipation and lightweight aluminum nitride substrate, including the following steps:

[0079] Step 1: Add 88g of aluminum nitride powder (purity > 99.5%, oxygen content < 0.5%, particle size < 3μm) to 70mL of ethanol, then add 4g of modified dispersant and mix to obtain modified aluminum nitride powder; mix the modified aluminum nitride powder with 7.2g of composite sintering aid and ball mill for 10h to obtain pretreated mixed powder;

[0080] Step 2: Add 8g of pretreated mixed powder to a container containing 0.11g of polyvinyl butyral, 0.14g of dibutyl phthalate and 10mL of ethanol, ball mill, vacuum degas, and obtain a slurry. Then coat the slurry onto a carrier, dry, and obtain a green sheet. Cut, stack, laminate, and remove the glue. The heating rate during the glue removal process is 1℃ / min. Heat to 550℃ and hold for 2h under nitrogen atmosphere to obtain a green body.

[0081] Step 3: Place the billet into the sintering furnace and evacuate it to 10°C. -2 After Pa, the temperature is raised to 1000℃, then nitrogen gas is introduced, and the temperature is raised to 1800℃ at a heating rate of 5℃ / min and held for 6 hours. After the treatment, the temperature is cooled to 550℃ at a cooling rate of 3℃ / min, and the pressure is released to obtain the sintered substrate. Then it is placed in the working chamber, vacuumed, and reacted at 1600℃ high temperature, 200MPa high pressure, and argon atmosphere for 3 hours. After the reaction, it is cooled, ground, and polished to obtain a high heat dissipation and lightweight aluminum nitride substrate.

[0082] Comparative Example 1: Compared with Example 1, Comparative Example 1 did not add any modified dispersant during the preparation of the high heat dissipation and lightweight aluminum nitride substrate, and all other conditions remained unchanged.

[0083] Comparative Example 2: Compared with Example 1, Comparative Example 2 did not add composite sintering aids during the preparation of the high heat dissipation and lightweight aluminum nitride substrate, and all other conditions remained unchanged.

[0084] Performance testing:

[0085] The high heat dissipation and lightweight aluminum nitride substrates prepared in Examples 1-5 and Comparative Examples 1-2 were subjected to performance tests. The bulk density of the samples was tested according to GB / T 25995-2010, and the thermal conductivity of the samples was tested according to GB / T 22588-2008. The test results are shown in Table 1.

[0086] Table 1

[0087]

[0088] As shown in Table 1, the test results indicate that aluminum nitride substrates with high density and excellent heat dissipation performance can be prepared using the methods of Examples 1-5. A comparison between Comparative Example 1 and Examples 1-5 reveals that adding a modified dispersant can effectively improve the density and heat dissipation performance of the aluminum nitride substrate; a comparison between Comparative Example 2 and Examples 1-5 reveals that adding a composite sintering aid can effectively improve the density and heat dissipation performance of the aluminum nitride substrate.

[0089] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0090] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a high-heat-dissipation, lightweight aluminum nitride substrate, characterized in that, Includes the following steps: Step 1: Add aluminum nitride powder to ethanol, then add a modified dispersant and mix to obtain modified aluminum nitride powder; mix the modified aluminum nitride powder with a composite sintering aid and ball mill to obtain a pretreated mixed powder; Step 2: Add the pretreated mixed powder to a container containing binder, plasticizer and ethanol, ball mill, vacuum degas to obtain slurry, then coat the slurry onto the carrier, dry to obtain blank, cut, stack, laminate, remove glue to obtain blank; Step 3: Place the billet into the sintering furnace, evacuate and heat it up, then introduce nitrogen gas and continue to heat and hold it. After the treatment is completed, cool it and depressurize it to obtain the sintered substrate. Then place it into the working chamber, evacuate it, and react it under high temperature and high pressure in an argon atmosphere. After the reaction is completed, cool it, grind it and polish it to obtain a high heat dissipation and lightweight aluminum nitride substrate. The preparation method of the composite sintering aid includes the following steps: S1: Add distilled water to a container, then add concentrated nitric acid, mix well, then add barium nitrate, cerium oxide, zirconium oxynitrate, yttrium nitrate hexahydrate and nickel nitrate in sequence, stir and mix, then add citric acid, then add ammonia to adjust the pH, stir the reaction, and heat to obtain the sintering aid precursor; S2: Add the sintering aid precursor into a muffle furnace and calcine to obtain a composite sintering aid.

2. The method for preparing a high-heat-dissipation and lightweight aluminum nitride substrate according to claim 1, characterized in that, In step one, the purity of aluminum nitride powder is >99.5%, the oxygen content is <0.5%, the particle size is <3μm, and the ratio of aluminum nitride powder, ethanol, modified dispersant and composite sintering aid is (80-90)g:(50-75)mL:(2-5)g:(2.4-10)g.

3. The method for preparing a high-heat-dissipation and lightweight aluminum nitride substrate according to claim 1, characterized in that, The preparation method of the modified dispersant includes the following steps: Q1: Add methyl allyl polyoxyethylene ether and mercaptoacetic acid to a container containing deionized water, heat, add ammonium persulfate aqueous solution dropwise, then add acrylic acid aqueous solution dropwise, and then add methanol solution containing methacryloyloxypropyltrimethoxysilane dropwise. After the addition is complete, react. After the reaction is complete, cool down, add sodium hydroxide aqueous solution, and rotary evaporate to obtain a mixture. Q2: Wash the dialysis bag with distilled water, then add the mixture into the dialysis bag, place it in deionized water, and dialyze it on a magnetic stirrer. After dialysis, freeze-crystallize and freeze-dry to obtain the modified dispersant.

4. The method for preparing a high-heat-dissipation and lightweight aluminum nitride substrate according to claim 3, characterized in that, In Q1, the molar ratio of methyl allyl polyoxyethylene ether, acrylic acid and methacryloyloxypropyltrimethoxysilane is (0.8-1.1):(0.88-1.16):(0.12-0.16).

5. The method for preparing a high-heat-dissipation and lightweight aluminum nitride substrate according to claim 3, characterized in that, In Q2, the dialysis bag has a molecular weight limit of 2000. During dialysis, the deionized water is changed every 2 hours. Once the color of the deionized water becomes lighter, the deionized water is changed to be changed every 12 hours.

6. The method for preparing a high-heat-dissipation and lightweight aluminum nitride substrate according to claim 1, characterized in that, In S1, the molar ratio of barium nitrate, cerium oxide, zirconium oxynitrate, yttrium nitrate hexahydrate, nickel nitrate, and citric acid is (0.88-1.21):(0.21-0.63):(0.22-0.61):(0.05-0.26):(0.01-0.08):(3.81-4.19); in S2, the calcination temperature is 1000-1200℃, and the calcination time is 6-8h.

7. The method for preparing a high-heat-dissipation and lightweight aluminum nitride substrate according to claim 1, characterized in that, In step two, the adhesive is composed of one or more of polyvinyl butyral, butyl acrylate, polyvinyl alcohol, and polyvinylpyrrolidone, and the plasticizer is composed of one or more of dibutyl phthalate, glycerol, polyethylene glycol, diethylene glycol diisooctanoate, and butyl benzyl phthalate.

8. The method for preparing a high-heat-dissipation and lightweight aluminum nitride substrate according to claim 1, characterized in that, In step three, the vacuum is evacuated to 10. -2 -10 -3 The temperature is raised to 800-1200℃, nitrogen is introduced, and the temperature is raised to 1700-1800℃ at a rate of 5-10℃ / min. The temperature is held for 2-6 hours, and then cooled to 550-590℃ at a rate of 3-5℃ / min. The high temperature is 1400-1600℃, the high pressure is 100-200MPa, and the reaction time is 1-3 hours.

9. A lightweight aluminum nitride substrate with high heat dissipation, characterized in that, It is prepared by the preparation method according to any one of claims 1-8.

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