A high thermal conductivity aluminum nitride ceramic substrate and its preparation method

Abstract

This application relates to a high thermal conductivity aluminum nitride ceramic substrate and its preparation method, belonging to the field of electronic ceramics. The high thermal conductivity aluminum nitride ceramic substrate is prepared using aluminum nitride casting paste, which comprises the following components in parts by weight: 80-100 parts modified aluminum nitride powder, 5-10 parts modified binder, 100-120 parts mixed solvent, 1-3 parts dispersant, and 1-5 parts plasticizer. This application has the effect of improving the density, thermal conductivity, and bending resistance of the aluminum nitride ceramic substrate, and can efficiently dissipate heat, making it suitable as a high-performance ceramic substrate material for assembling ultra-large-scale integrated circuits.

Description

Technical Field

[0001] This application relates to the field of electronic ceramics technology, and in particular to a high thermal conductivity aluminum nitride ceramic substrate and its preparation method. Background Technology

[0002] As the power and density of electronic components increase, the heat generated per unit volume also increases, placing higher demands on the overall performance of circuit boards. Ceramic substrates, with their excellent overall performance in insulation, thermal conductivity, thermal expansion, and chemical stability, are increasingly widely used as substrate materials. Among these, substrates based on alumina and beryllium oxide have been used for a long time; however, these two materials suffer from low thermal conductivity and toxicity, limiting their application.

[0003] Aluminum nitride ceramics possess high thermal conductivity, low dielectric constant and dielectric loss, and good electrical insulation properties. With a thermal expansion coefficient comparable to silicon and gallium arsenide, it is an ideal heat dissipation material for electronic packaging, efficiently dissipating heat from large components. It can serve as a high-performance ceramic substrate material for assembling very large-scale integrated circuits. As chip input power increases, the large heat generation and high output power of high power applications place higher demands on ceramic substrates. However, because aluminum nitride is a covalent compound with a low self-diffusion coefficient, it is difficult to sinter densely, resulting in an aluminum nitride thermal conductivity far lower than the theoretical value, leading to poor thermal conductivity that needs improvement. Summary of the Invention

[0004] To improve the thermal conductivity of aluminum nitride ceramic substrates, this application provides a high thermal conductivity aluminum nitride ceramic substrate and its preparation method.

[0005] This application provides a high thermal conductivity aluminum nitride ceramic substrate and its preparation method, which adopts the following technical solution:

[0006] In the first aspect, this application provides a high thermal conductivity aluminum nitride ceramic substrate, which adopts the following technical solution:

[0007] A high thermal conductivity aluminum nitride ceramic substrate, wherein the high thermal conductivity aluminum nitride ceramic substrate is prepared using aluminum nitride casting paste, the aluminum nitride casting paste comprising the following components in parts by weight:

[0008] 80-100 parts of modified aluminum nitride powder

[0009] 5-10 parts of modified adhesive

[0010] 100-120 parts of mixed solvent

[0011] 1-3 parts dispersant

[0012] Plasticizer 1-5 parts.

[0013] Modified aluminum nitride powder, through modification treatment, results in a denser aluminum nitride ceramic substrate with good thermal conductivity after sintering. Modified binder, through modification treatment, improves the compatibility between the modified binder and modified aluminum nitride powder, thereby improving the dispersibility and stability of aluminum nitride casting slurry. Mixed solvent, through compounding, improves the wettability of modified aluminum nitride powder, enhances the dispersibility and compatibility of each component in aluminum nitride casting slurry, and thus improves the density and thermal conductivity of aluminum nitride ceramic substrate.

[0014] Preferably, the modified aluminum nitride powder comprises high-purity ultrafine aluminum nitride powder and sintering aids.

[0015] Sintering aids can form solid solutions with high-purity ultrafine aluminum nitride powder, change the crystal structure, promote the movement between particles, thereby accelerating the sintering process, causing oxygen to precipitate into the grain boundary phase, forming island-like grain boundary phases, and improving the thermal conductivity and bending strength of aluminum nitride ceramic substrates.

[0016] Preferably, the sintering aid is coated on the surface of high-purity ultrafine aluminum nitride powder by chemical deposition. The raw materials for preparing the sintering aid include anhydrous samarium chloride and anhydrous ammonium carbonate, and the amount of anhydrous samarium chloride is 3-5% of the mass of the high-purity ultrafine aluminum nitride powder.

[0017] By coating sintering aids onto the surface of high-purity ultrafine aluminum nitride powder using chemical deposition, the uniformity of sintering aid distribution can be improved, thereby reducing the oxygen content in the aluminum nitride ceramic substrate and enhancing its thermal conductivity and flexural strength.

[0018] Preferably, the modified aluminum nitride powder is prepared using the following steps:

[0019] A methanol solution of samarium chloride was prepared as the precipitating solution, and a methanol solution of ammonium bicarbonate was prepared as the precipitant. High-purity ultrafine aluminum nitride powder was added to the precipitating solution in a neutral gas atmosphere. The precipitant was added under heating and stirring conditions, and the precipitate was obtained by filtration. The precipitate was calcined and then ground to obtain modified aluminum nitride powder.

[0020] The aluminum nitride ceramic substrate prepared according to the above steps has high thermal conductivity and bending strength.

[0021] Preferably, the raw materials for preparing the modified adhesive include polyvinyl alcohol, glutaraldehyde, and maleic anhydride.

[0022] Modifying polyvinyl alcohol with glutaraldehyde and maleic anhydride can increase the content of active groups on the surface of polyvinyl alcohol, improve the dispersibility and compatibility of the modified binder, and thus improve the thermal conductivity and bending resistance of aluminum nitride ceramic substrates.

[0023] Preferably, the mass ratio of polyvinyl alcohol, glutaraldehyde and maleic anhydride is 1:0.15:(0.1-0.2).

[0024] The aluminum nitride ceramic substrate prepared according to the above steps has good thermal conductivity and bending resistance.

[0025] Preferably, the modified binder further includes modified carbon nanoparticles.

[0026] By modifying the nano-carbon powder, its dispersibility and compatibility can be improved, thereby enhancing the thermal conductivity and bending resistance of the aluminum nitride ceramic substrate.

[0027] Preferably, the modified carbon nanoparticles comprise carbon nanoparticles and 1,4-butadiene.

[0028] 1,4-Butadiene reacts with carbon nanoparticles to increase the alkenyl groups on the surface of the carbon nanoparticles, thereby improving the reactivity and compatibility of the modified carbon nanoparticles and thus enhancing the thermal conductivity and flexural strength of the aluminum nitride ceramic substrate.

[0029] Preferably, the mixed solvent includes xylene and isopropanol.

[0030] The mixed solvent obtained by combining xylene and isopropanol can effectively wet modified aluminum nitride ceramic powder, improve the suspension properties of the powder and the rheological properties of aluminum nitride ceramic slurry, thereby enhancing the thermal conductivity and bending resistance of aluminum nitride ceramic substrate.

[0031] Secondly, this application provides a method for preparing a high thermal conductivity aluminum nitride ceramic substrate, which adopts the following technical solution: A method for preparing a high thermal conductivity aluminum nitride ceramic substrate, comprising the following steps:

[0032] The modified aluminum nitride powder was dispersed in a mixed solvent and ball-milled. After filtration and drying, the ball-milled powder was obtained. The ball-milled powder was then sieved to obtain ultrafine modified aluminum nitride powder with uniform particle size.

[0033] Ultrafine modified aluminum nitride powder, modified binder, mixed solvent, dispersant and plasticizer are mixed and ball-milled to obtain a slurry. The slurry is degassed to obtain a degassed slurry. The degassed slurry is then cast into a green body.

[0034] The green body is subjected to powdering and aging treatment to obtain the treated green body;

[0035] The treated green body is subjected to debinding treatment to obtain a debinded green body;

[0036] The green body after debinding is sintered to obtain a rough product. The rough product is then surface treated to obtain a high thermal conductivity aluminum nitride ceramic substrate.

[0037] The aluminum nitride ceramic substrate prepared according to the above steps has good thermal conductivity and bending resistance.

[0038] In summary, this application includes at least one of the following beneficial technical effects:

[0039] 1. Modified aluminum nitride powder, through modification treatment, results in a denser aluminum nitride ceramic substrate with good thermal conductivity after sintering. Modified binder, through modification treatment, can improve the compatibility between the modified binder and modified aluminum nitride powder, thereby improving the dispersibility and stability of aluminum nitride casting slurry. Mixed solvent, through compounding, can improve the wettability of modified aluminum nitride powder, improve the dispersibility and compatibility of each component in aluminum nitride casting slurry, thereby improving the density and thermal conductivity of aluminum nitride ceramic substrate.

[0040] 2. By coating sintering aids onto the surface of high-purity ultrafine aluminum nitride powder through chemical deposition, the uniformity of sintering aid distribution can be improved, thereby reducing the oxygen content in the aluminum nitride ceramic substrate and improving the thermal conductivity and flexural strength of the aluminum nitride ceramic substrate.

[0041] 3. By modifying the binder and adding modified nano-carbon powder, the compatibility and stability of the aluminum nitride casting slurry are improved, which promotes the densification of the aluminum nitride ceramic substrate and the removal of oxygen elements during the sintering process, reduces the oxygen content, and thus improves the density, thermal conductivity and bending resistance of the aluminum nitride ceramic substrate. Detailed Implementation

[0042] This application discloses a high thermal conductivity aluminum nitride ceramic substrate and its preparation method. The following embodiments provide a more detailed description of this application:

[0043] Example 1

[0044] Preparation of modified aluminum nitride powder

[0045] 4.5 g of anhydrous samarium chloride was prepared into a 1 mol / L samarium chloride methanol solution as the precipitant, and a 1.5 mol / L ammonium bicarbonate methanol solution was prepared as the precipitant. 150 g of high-purity ultrafine aluminum nitride powder was added to the precipitant solution. 50 mL of precipitant was added under the condition of stirring at 200 r / min in a 35℃ water bath. After precipitation reaction for 1 h, the precipitate was obtained by filtration. The precipitate was calcined at 900℃ for 2 h and then ground to obtain modified aluminum nitride powder.

[0046] Preparation of modified adhesives

[0047] 24g of polyvinyl alcohol (molecular weight approximately 25,000) was dissolved in 100mL of deionized water and stirred in a water bath at 80℃ for 2h to obtain a polyvinyl alcohol aqueous solution. After the polyvinyl alcohol aqueous solution was cooled to 30℃, sulfuric acid solution was added to adjust the pH of the polyvinyl alcohol aqueous solution to 3. 3.6g of glutaraldehyde and 2.4g of maleic anhydride were added dropwise at a rate of 30 drops / min, and the reaction was stirred at 800r / min for 2h. The product was obtained by filtration, washed with deionized water until neutral, and dried in an oven at 80℃ for 6h to obtain modified polyvinyl alcohol powder.

[0048] 10g of nano-carbon powder and 2g of 1,4-butadiene were dispersed in ethanol and stirred at 200r / min for 1h. After filtration, the mixture was dried in an oven at 80℃ for 6h to obtain modified nano-carbon powder. 4.5g of modified nano-carbon powder and 15.5g of modified polyvinyl alcohol powder were mixed to obtain a modified binder.

[0049] Fabrication of high thermal conductivity aluminum nitride ceramic substrates

[0050] The modified aluminum nitride powder prepared above was dispersed in 100 mL of a mixed solvent to obtain a suspension. The volume ratio of xylene to isopropanol in the mixed solvent was 1:1. The suspension was ball-milled for 8 h. After filtering, the ball-milled suspension was dried in an oven at 100 °C for 4 h to obtain ball-milled powder. The ball-milled powder was passed through a 6000-mesh sieve to obtain ultrafine modified aluminum nitride powder with uniform particle size. 80 g of ultrafine modified aluminum nitride powder, 5 g of modified binder, 100 g of mixed solvent, 1 g of dispersant, and 1 g of plasticizer were mixed and ball-milled. The dispersant was triolein, and the plasticizer was diethyl phthalate to obtain a slurry. The slurry was deaerated to obtain a deaerated slurry. The slurry was cast into a green body to obtain a green body. The green body was then coated with ultrafine modified aluminum nitride powder and aged for 24 hours to obtain a treated green body. The treated green body was then debonded in a debonding furnace, heated to 500℃ at a rate of 1℃ / min and held for 120 minutes to obtain a debonded green body. The debonded green body was then sintered at 1800℃ for 4 hours, then cooled from 1800℃ to 500℃ at a rate of 5℃ / min, and then cooled to 30℃ at a rate of 3℃ / min to obtain a rough product. The rough product was then surface treated by immersing it in a 10% sodium carbonate solution for 2 hours and then drying it to obtain a high thermal conductivity aluminum nitride ceramic substrate.

[0051] Example 2

[0052] Preparation of modified aluminum nitride powder

[0053] 7.5 g of anhydrous samarium chloride was prepared into a 1 mol / L samarium chloride methanol solution as the precipitant, and a 1.5 mol / L ammonium bicarbonate methanol solution was prepared as the precipitant. 150 g of high-purity ultrafine aluminum nitride powder was added to the precipitant solution. 50 mL of precipitant was added under the condition of stirring at 200 r / min in a 35℃ water bath. After precipitation reaction for 1 h, the precipitate was obtained by filtration. The precipitate was calcined at 900℃ for 2 h and then ground to obtain modified aluminum nitride powder.

[0054] Preparation of modified adhesives

[0055] 22.22 g of polyvinyl alcohol (molecular weight approximately 25,000) was dissolved in 100 mL of deionized water and stirred in a water bath at 80 °C for 2 h to obtain a polyvinyl alcohol aqueous solution. After the polyvinyl alcohol aqueous solution was cooled to 30 °C, sulfuric acid solution was added to adjust the pH of the polyvinyl alcohol aqueous solution to 3. 3.33 g of glutaraldehyde and 4.45 g of maleic anhydride were added dropwise at a rate of 30 drops / min, and the reaction was stirred at 800 r / min for 2 h. The product was obtained by filtration, washed with deionized water until neutral, and dried in an oven at 80 °C for 6 h to obtain modified polyvinyl alcohol powder.

[0056] 10g of nano-carbon powder and 2g of 1,4-butadiene were dispersed in ethanol and stirred at 200r / min for 1h. After filtration, the mixture was dried in an oven at 80℃ for 6h to obtain modified nano-carbon powder. 4.5g of modified nano-carbon powder and 15.5g of modified polyvinyl alcohol powder were mixed to obtain a modified binder.

[0057] Fabrication of high thermal conductivity aluminum nitride ceramic substrates

[0058] The modified aluminum nitride powder prepared above was dispersed in 100 mL of a mixed solvent to obtain a suspension. The volume ratio of xylene to isopropanol in the mixed solvent was 1:1. The suspension was ball-milled for 8 hours. After filtering, the ball-milled suspension was dried in an oven at 100°C for 4 hours to obtain ball-milled powder. The ball-milled powder was passed through a 6000-mesh sieve to obtain ultrafine modified aluminum nitride powder with uniform particle size. 100 g of ultrafine modified aluminum nitride powder, 10 g of modified binder, 120 g of mixed solvent, 3 g of dispersant, and 5 g of plasticizer were mixed and ball-milled. The dispersant was triolein, and the plasticizer was diethyl phthalate to obtain a slurry. The slurry was deaerated to obtain a deaerated slurry. The slurry was then cast to obtain a green body. The green body was then coated with ultrafine modified aluminum nitride powder and aged for 24 hours to obtain a treated green body. The treated green body was then debonded in a debonding furnace, heated to 500°C at a rate of 1°C / min and held for 120 minutes to obtain a debonded green body. The debonded green body was then sintered at 1800°C for 4 hours, then cooled from 1800°C to 500°C at a rate of 5°C / min, and then cooled to 30°C at a rate of 3°C / min to obtain a rough product. The rough product was then surface treated by immersing it in a 10% sodium carbonate solution for 2 hours and then drying it to obtain a high thermal conductivity aluminum nitride ceramic substrate.

[0059] Example 3

[0060] Preparation of modified aluminum nitride powder

[0061] 6g of anhydrous samarium chloride was prepared into a 1mol / L samarium chloride methanol solution as the precipitant, and a 1.5mol / L ammonium bicarbonate methanol solution was prepared as the precipitant. 150g of high-purity ultrafine aluminum nitride powder was added to the precipitant solution. 50mL of precipitant was added under the condition of stirring at 200r / min in a 35℃ water bath. After precipitation reaction for 1h, the precipitate was obtained by filtration. The precipitate was calcined at 900℃ for 2h and then ground to obtain modified aluminum nitride powder.

[0062] Preparation of modified adhesives

[0063] 23.08 g of polyvinyl alcohol (molecular weight approximately 25,000) was dissolved in 100 mL of deionized water and stirred in a water bath at 80 °C for 2 h to obtain a polyvinyl alcohol aqueous solution. After the polyvinyl alcohol aqueous solution was cooled to 30 °C, sulfuric acid solution was added to adjust the pH of the polyvinyl alcohol aqueous solution to 3. 3.46 g of glutaraldehyde and 3.46 g of maleic anhydride were added dropwise at a rate of 30 drops / min, and the reaction was stirred at 800 r / min for 2 h. The product was obtained by filtration, washed with deionized water until neutral, and dried in an oven at 80 °C for 6 h to obtain modified polyvinyl alcohol powder.

[0064] 10g of nano-carbon powder and 2g of 1,4-butadiene were dispersed in ethanol and stirred at 200r / min for 1h. After filtration, the mixture was dried in an oven at 80℃ for 6h to obtain modified nano-carbon powder. 4.5g of modified nano-carbon powder and 15.5g of modified polyvinyl alcohol powder were mixed to obtain a modified binder.

[0065] Fabrication of high thermal conductivity aluminum nitride ceramic substrates

[0066] The modified aluminum nitride powder prepared above was dispersed in 100 mL of a mixed solvent to obtain a suspension. The volume ratio of xylene to isopropanol in the mixed solvent was 1:1. The suspension was ball-milled for 8 hours. After filtering, the ball-milled suspension was dried in an oven at 100°C for 4 hours to obtain ball-milled powder. The ball-milled powder was passed through a 6000-mesh sieve to obtain ultrafine modified aluminum nitride powder with uniform particle size. 90 g of ultrafine modified aluminum nitride powder, 7.5 g of modified binder, 110 g of mixed solvent, 2 g of dispersant, and 3 g of plasticizer were mixed and ball-milled. The dispersant was triolein, and the plasticizer was diethyl phthalate to obtain a slurry. The slurry was deaerated to obtain a deaerated slurry. The slurry was then cast to obtain a green body. The green body was then coated with ultrafine modified aluminum nitride powder and aged for 24 hours to obtain a treated green body. The treated green body was then debonded in a debonding furnace, heated to 500°C at a rate of 1°C / min and held for 120 minutes to obtain a debonded green body. The debonded green body was then sintered at 1800°C for 4 hours, then cooled from 1800°C to 500°C at a rate of 5°C / min, and then cooled to 30°C at a rate of 3°C / min to obtain a rough product. The rough product was then surface treated by immersing it in a 10% sodium carbonate solution for 2 hours and then drying it to obtain a high thermal conductivity aluminum nitride ceramic substrate.

[0067] Example 4

[0068] Example 4 is based on Example 3. The only difference between Example 4 and Example 3 is that the amount of anhydrous samarium chloride used in Example 4 is 3g.

[0069] Example 5

[0070] Example 5 is based on Example 3. The only difference between Example 5 and Example 3 is that the amount of anhydrous samarium chloride used in Example 5 is 9g.

[0071] Example 6

[0072] Example 6 is based on Example 3. The only difference between Example 6 and Example 3 is that in Example 6, the amount of polyvinyl alcohol is 25g, the amount of glutaraldehyde is 3.75g, and the amount of maleic anhydride is 1.25g.

[0073] Example 7

[0074] Example 7 is based on Example 3. The only difference between Example 7 and Example 3 is that in Example 7, the amount of polyvinyl alcohol is 20.69g, the amount of glutaraldehyde is 3.1g, and the amount of maleic anhydride is 6.21g.

[0075] Example 8

[0076] Example 8 is based on Example 3. The only difference between Example 8 and Example 3 is that glutaraldehyde is not added in the step of preparing the modified binder in Example 8.

[0077] Example 9

[0078] Example 9 is based on Example 3. The only difference between Example 9 and Example 3 is that maleic anhydride is not added in the step of preparing the modified binder in Example 9.

[0079] Example 10

[0080] Example 10 is based on Example 3. The only difference between Example 10 and Example 3 is that modified carbon nanoparticles are not added in the step of preparing the modified binder in Example 10.

[0081] Example 11

[0082] Example 11 is based on Example 3. The only difference between Example 11 and Example 3 is that the modified carbon nanoparticles in the step of preparing the modified binder are replaced with carbon nanoparticles.

[0083] Comparative Example 1

[0084] Comparative Example 1 is based on Example 3. The only difference between Comparative Example 1 and Example 3 is that the modified aluminum nitride powder is replaced with high-purity ultrafine aluminum nitride powder and samarium oxide in Comparative Example 1.

[0085] Comparative Example 2

[0086] Comparative Example 2 is based on Example 3. The only difference between Comparative Example 2 and Example 3 is that the modified binder in Comparative Example 2 is replaced with polyvinyl butyral.

[0087] Comparative Example 3

[0088] Comparative Example 3 is based on Example 3, except that the mixed solvent in Comparative Example 3 is replaced with isopropanol.

[0089] Comparative Example 4

[0090] Comparative Example 4 is based on Example 3, except that the mixed solvent in Comparative Example 4 is replaced with xylene.

[0091] Performance testing

[0092] The standard was selected as "GJB 3520-99 Specification for Aluminum Nitride Ceramic Substrates". The density of the samples was tested by Archimedes' water displacement method, the bending strength of the samples was tested by the three-point bending test, and the thermal conductivity of the samples was tested by the laser flash method. Three samples were prepared for each sample, and the average value was taken after measurement. The results are recorded in Table 1.

[0093] Table 1. Test results of density, thermal conductivity, and flexural strength of aluminum nitride ceramic substrates.

[0094]

[0095] As shown in Table 1, the densities of Examples 1-3 are greater than 3.35 g / cm³. 3 The thermal conductivity is greater than 181 W / (m·K) and the bending strength is greater than 478 MPa, which shows that the aluminum nitride ceramic substrate prepared in this application has good density, thermal conductivity and bending strength.

[0096] As shown in Table 1, the only differences between Examples 4 and 5 and Example 3 are: in Example 4, the amount of anhydrous samarium chloride used is 2% of the mass of high-purity ultrafine aluminum nitride powder; in Example 5, the amount of anhydrous samarium chloride used is 6% of the mass of high-purity ultrafine aluminum nitride powder; and in Examples 4 and 5, the density is less than 3.34 g / cm³. 3 The thermal conductivity is less than 179 W / (m·K), and the flexural strength is less than 472 MPa. The density in Example 3 is 3.37 g / cm3, the thermal conductivity is 187 W / (m·K), and the flexural strength is 489 MPa. Compared with Example 3, the density, thermal conductivity, and flexural strength of Examples 4 and 5 are all reduced. This is because the amount of samarium chloride precipitated on the surface of high-purity ultrafine aluminum nitride powder is changed, which in turn affects the amount of sintering aid. Too much or too little sintering aid will affect the sintering performance of aluminum nitride ceramic substrate, thus reducing the density, thermal conductivity, and flexural strength of aluminum nitride ceramic substrate.

[0097] As shown in Table 1, the differences between Examples 6 and 7 and Example 3 are only as follows: in Example 6, the mass ratio of polyvinyl alcohol, glutaraldehyde, and maleic anhydride is 1:0.15:0.05; in Example 7, the mass ratio of polyvinyl alcohol, glutaraldehyde, and maleic anhydride is 1:0.15:0.3; and in Examples 6 and 7, the density is less than 3.35 g / cm³. 3The thermal conductivity is less than 180 W / (m·K), and the flexural strength is less than 479 MPa. Compared with Example 3, Examples 6 and 7 show a decrease in density, thermal conductivity, and flexural strength. This is because the mass ratio of polyvinyl alcohol, glutaraldehyde, and maleic anhydride is not within the specified range. Too much or too little maleic anhydride will affect the reaction performance and bonding performance of the modified binder, reduce the stability and compatibility of the aluminum nitride casting slurry, and affect the performance of the green body, thus resulting in a decrease in density, thermal conductivity, and flexural strength.

[0098] As shown in Table 1, the only differences between Examples 8 and 9 and Example 3 are: glutaraldehyde is not added in the modified binder preparation step of Example 8, maleic anhydride is not added in the modified binder preparation step of Example 9, and the density in Examples 8 and 9 is less than 3.33 g / cm³. 3 The thermal conductivity is less than 175 W / (m·K), and the flexural strength is less than 471 MPa. Compared with Example 3, Examples 8 and 9 show a decrease in density, thermal conductivity, and flexural strength. This is because without the addition of glutaraldehyde or maleic anhydride, the active groups on the surface of the modified binder are reduced, the reactivity decreases, and the dispersibility and compatibility of the aluminum nitride casting slurry decrease, thus reducing the density, thermal conductivity, and flexural strength of the aluminum nitride ceramic substrate.

[0099] As shown in Table 1, the only difference between Examples 10 and 11 and Example 3 is that: in Example 10, modified carbon nanoparticles are not added in the step of preparing the modified binder; in Example 11, the modified carbon nanoparticles in the step of preparing the modified binder are replaced with carbon nanoparticles; and the density in Examples 10 and 11 is less than 3.33 g / cm³. 3 The thermal conductivity is less than 174 W / (m·K), and the flexural strength is less than 475 MPa. Compared with Example 3, Examples 10 and 11 show a decrease in density, thermal conductivity, and flexural strength. This is because without the addition of modified nano-carbon powder, the green body lacks carbon, which reduces sintering performance and increases oxygen content. Without modification of the nano-carbon powder, its dispersibility and compatibility decrease, thus affecting the stability of the aluminum nitride casting slurry, resulting in a decrease in density, thermal conductivity, and flexural strength.

[0100] As shown in Table 1, the only difference between Comparative Example 1 and Example 3 is that the modified aluminum nitride powder in Comparative Example 1 was replaced with high-purity ultrafine aluminum nitride powder and samarium oxide, and the density in Comparative Example 1 was 3.30 g / cm³. 3The thermal conductivity was 161 W / (m·K), and the flexural strength was 457 MPa. Compared with Comparative Example 1 and Example 3, the density, thermal conductivity, and flexural strength were all significantly reduced. This is because the sintering aid samarium oxide was added alone instead of coating the surface of the high-purity ultrafine aluminum nitride powder. The distribution of the sintering aid was uneven, which affected the sintering performance of the aluminum nitride ceramic substrate, resulting in a significant decrease in density, thermal conductivity, and flexural strength.

[0101] As shown in Table 1, the only difference between Comparative Example 2 and Example 3 is that the modified binder in Comparative Example 2 was replaced with polyvinyl butyral, and the density in Comparative Example 2 was 3.31 g / cm³. 3 The thermal conductivity was 158 W / (m·K), and the flexural strength was 452 MPa. Compared with Comparative Example 2 and Example 3, the density, thermal conductivity, and flexural strength all decreased significantly. This is because replacing the modified binder with polyvinyl butyral, lacking the modification treatment of acid anhydride and the doping of modified carbon nanoparticles, reduced the adhesion and compatibility of the modified binder. During the sintering process, the lack of carbon powder introduction led to an increase in oxygen content, affecting the performance of the aluminum nitride crystal phase, thus resulting in a significant decrease in density, thermal conductivity, and flexural strength.

[0102] As shown in Table 1, the only difference between Comparative Examples 3 and 4 and Example 3 is that the mixed solvent in Comparative Example 3 was replaced with isopropanol, and the mixed solvent in Comparative Example 4 was replaced with xylene. The densities in Comparative Examples 3 and 4 are less than 3.33 g / cm³. 3 The thermal conductivity is less than 167 W / (m·K), and the flexural strength is less than 462 MPa. Compared with Comparative Examples 3 and 4 and Example 3, the density, thermal conductivity, and flexural strength are all significantly reduced. This is because replacing the mixed solvent with a single isopropanol or xylene reduces the wetting properties of the solvent, and decreases the rheological properties and stability of the aluminum nitride casting slurry, thereby significantly reducing the density, thermal conductivity, and flexural strength.

[0103] This specific embodiment is merely an explanation of this application and is not intended to limit it. Based on the above description, those skilled in the art can make various changes and modifications without departing from the technical concept of this application. The technical scope of this application is not limited to the contents of the specification but must be determined according to the scope of the claims.

Claims

1. A high thermal conductivity aluminum nitride ceramic substrate, characterized in that: The high thermal conductivity aluminum nitride ceramic substrate is prepared using aluminum nitride casting paste, which comprises the following components in parts by weight: 80-100 parts of modified aluminum nitride powder 5-10 parts of modified adhesive 100-120 parts of mixed solvent 1-3 parts dispersant Plasticizer 1-5 parts; The modified aluminum nitride powder includes high-purity ultrafine aluminum nitride powder and sintering aids; The sintering aid is coated onto the surface of high-purity ultrafine aluminum nitride powder by chemical deposition. The raw materials for preparing the sintering aid include anhydrous samarium chloride and anhydrous ammonium carbonate, and the amount of anhydrous samarium chloride is 3-5% of the mass of the high-purity ultrafine aluminum nitride powder. The raw materials for preparing the modified binder include polyvinyl alcohol, glutaraldehyde and maleic anhydride. The mass ratio of polyvinyl alcohol, glutaraldehyde, and maleic anhydride is 1:0.15:(0.1-0.2). The modified binder also includes modified nano-carbon powder; The modified nano-carbon powder includes nano-carbon powder and 1,4-butadiene; The mixed solvent is xylene and isopropanol.

2. A high thermal conductivity aluminum nitride ceramic substrate as described in claim 1, characterized in that: The modified aluminum nitride powder is prepared using the following steps: A methanol solution of samarium chloride was prepared as the precipitating solution, and a methanol solution of ammonium bicarbonate was prepared as the precipitant. High-purity ultrafine aluminum nitride powder was added to the precipitating solution in a neutral gas atmosphere. The precipitant was added under heating and stirring conditions, and the precipitate was obtained by filtration. The precipitate was calcined and then ground to obtain modified aluminum nitride powder.

3. A method for preparing a high thermal conductivity aluminum nitride ceramic substrate as described in claim 1, characterized in that: Prepared using the following steps: The modified aluminum nitride powder was dispersed in a mixed solvent and ball-milled. After filtration and drying, the ball-milled powder was obtained. The ball-milled powder was then sieved to obtain ultrafine modified aluminum nitride powder with uniform particle size. Ultrafine modified aluminum nitride powder, modified binder, mixed solvent, dispersant and plasticizer are mixed and ball-milled to obtain a slurry. The slurry is degassed to obtain a degassed slurry. The degassed slurry is then cast into a green body. The green body is subjected to powdering and aging treatment to obtain the treated green body; The treated green body is subjected to debinding treatment to obtain a debinded green body; The green body after debinding is sintered to obtain a rough product. The rough product is then surface treated to obtain a high thermal conductivity aluminum nitride ceramic substrate.

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