Aluminum nitride high-temperature co-fired via fill tungsten paste and method of making same

Abstract

The application relates to the field of electronic materials, and discloses an aluminum nitride high-temperature co-firing hole-filling tungsten slurry and a preparation method thereof. The hole-filling tungsten slurry comprises composite modified tungsten-copper composite powder, a composite functional phase and an organic carrier. The composite modified tungsten-copper composite powder is prepared by adopting a spray drying, calcining and reducing process to prepare tungsten-copper composite powder and then modified by adopting an airflow crushing method. Then, carboxyl-terminated hyperbranched polyester is used to cooperate with gamma-aminopropyl triethoxysilane to form on the surface of the prepared modified tungsten-copper composite powder. The performance is upgraded by optimizing the component proportioning ratio and the preparation process of the tungsten slurry. The tungsten slurry takes the composite modified tungsten-copper composite powder as the main body, is matched with the composite functional phase composed of nano aluminum-yttrium alloy powder and a low-temperature activated sintering aid, is compounded with the organic carrier, and is subjected to gradient three-roller rolling, vacuum degassing and other processes to improve the slurry homogeneity, and the interface bonding strength, the sintering density, the electrical conductivity and the mechanical properties are improved.

Description

Technical Field

[0001] This invention belongs to the field of electronic materials technology, specifically relating to a high-temperature co-fired aluminum nitride tungsten paste for filling pores and its preparation method. Background Technology

[0002] High-temperature co-fired ceramics, as a high-performance electronic packaging material, have broad application prospects in fields such as detection, communication, smart wearables, and low-altitude economy due to their excellent thermal conductivity, high insulation strength, and multi-layer wiring integration capabilities. Through-hole filling is one of the key processes in the manufacturing process of high-temperature co-fired ceramics, which directly affects the reliability of electrical connections between different layers inside the component. This process mainly involves metallizing the through-holes of the punched ceramic sheet, that is, filling the through-holes with a metal paste that has a conductive function.

[0003] Tungsten has a high melting point and good electrical and thermal conductivity, making it an ideal conductor paste material for aluminum nitride ceramic substrates. However, traditional conductor pastes suffer from problems such as easy oxidation and weak interfacial bonding. Furthermore, as the power of circuit modules continues to increase, the current carrying capacity of tungsten conductor pastes can no longer meet the requirements, affecting the signal transmission performance of high-temperature co-fired ceramic packages. In order to meet the needs of higher bandwidth and faster transmission rates, it is urgent to prepare tungsten-based conductor pastes with lower sheet resistance to meet the application needs of aluminum nitride ceramic substrates in high-end electronics. Summary of the Invention

[0004] To address the shortcomings mentioned in the background art, the present invention aims to provide a high-temperature co-fired aluminum nitride pore-filling tungsten slurry and its preparation method. By optimizing the composition ratio and preparation process of the tungsten slurry, performance upgrades are achieved. The tungsten slurry is mainly composed of composite modified tungsten-copper composite powder, combined with a composite functional phase composed of nano-aluminum-yttrium alloy powder and low-temperature activated sintering aid. It is also combined with an organic carrier and subjected to gradient three-roll rolling, vacuum degassing and other processes to improve the homogeneity of the slurry, thereby improving the interfacial bonding strength, sintering density, conductivity and mechanical properties.

[0005] The objective of this invention can be achieved through the following technical solutions: A high-temperature co-fired aluminum nitride tungsten paste for filling pores comprises, by mass percentage: 78-82% composite modified tungsten-copper composite powder, 10-14% composite functional phase, and 7-11% organic carrier; The modified tungsten-copper composite powder is prepared by spray drying, calcination and reduction processes to obtain tungsten-copper composite powder with a copper content of 10~30 wt.%, and modified by airflow crushing method. Then, it is grafted onto the surface of the prepared modified tungsten-copper composite powder using terminal carboxyl hyperbranched polyester in synergy with γ-aminopropyltriethoxysilane.

[0006] Preferably, the composite functional phase is composed of nano-aluminum-yttrium alloy powder and low-temperature activated sintering aid in a mass ratio of 1:2~4.

[0007] Preferably, the aluminum-yttrium atomic ratio in the nano-aluminum-yttrium alloy powder is 3:1; the low-temperature activation sintering aid is SiO2-CuO-TiO2.

[0008] Preferably, the preparation method of the composite modified tungsten-copper composite powder includes the following steps: ① Ammonium paratungstate and copper nitrate were continuously stirred in deionized water at 90℃. An appropriate amount of citric acid was added to promote the dissolution of ammonium paratungstate. After a uniform and transparent solution was formed, it was spray-dried to obtain precursor powder. ② The precursor powder is calcined in air at 600~700℃ to remove ammonium ions, nitrate ions and organic carbon from the precursor powder, and then reduced with hydrogen at 750~900℃ to obtain tungsten copper composite powder. ③ The tungsten-copper composite powder was modified by airflow crushing to obtain modified tungsten-copper composite powder; ④ The modified tungsten copper composite powder was ultrasonically dispersed in ethanol, and then a mixed solution of γ-aminopropyltriethoxysilane, deionized water and ethanol was added. The mixture was ultrasonically stirred for 2 hours, and then filtered, washed and dried to prepare the aminated modified tungsten copper composite powder. ⑤ The aminated modified tungsten-copper composite powder was ultrasonically dispersed in acetone solvent, and then 0.5% by mass of terminal carboxyl hyperbranched polyester and p-toluenesulfonic acid were added. The mixture was then magnetically stirred at 80~100℃ for 30~40 min, and subsequently filtered, washed and dried to prepare the composite modified tungsten-copper composite powder.

[0009] Preferably, the air inlet temperature of the spray dryer is set to 180°C, the atomizing disc rotation speed is set to 18000 rpm, and the feeding speed is set to 3 kg / h; the copper content in the tungsten-copper composite powder is 10~30 wt.%.

[0010] Preferably, the gas pressure of the airflow crusher is set to 0.5~0.7MPa, the feed rate is set to 4.5~5kg / h, and the classifier speed is set to 4000~4200rpm.

[0011] Preferably, the particle size parameter of the modified tungsten-copper composite powder is: D 10 The thickness is 1.15~1.25μm, D 50 The diameter is 2.55~2.65μm, D 90 The thickness is 4.55~4.67μm.

[0012] The method for preparing the aluminum nitride high-temperature co-fired pore-filling tungsten paste as described above includes the following steps: S1. Preparation of organic carrier: Organic binder is added to organic solvent in batches to dissolve it, then dispersant and plasticizer are added in sequence, heated and stirred evenly, cooled and filtered to obtain organic carrier; S2. Preparation of slurry precursor: Take the composite modified tungsten copper composite powder and composite functional phase and add them to the mixing equipment. Dry premix for 30 min under argon protection. After thorough mixing, add them to the organic carrier and continue stirring for 30 min to obtain the slurry precursor. S3. Homogenization rolling on a three-roll mill: The initial slurry is added to a three-roll mill for repeated rolling. The initial gap between the rolls is 120µm, and the gap is gradually reduced to 15µm. The total number of rolling passes is 20 to obtain a homogeneous slurry. S4. Degassing and Storage: The homogeneous slurry is transferred to a vacuum degassing device, the vacuum degree is set to -0.09MPa, the degassing time is 30min, and after degassing, it is filtered. After filtration, the slurry is put into a sealed container, argon gas is introduced into the container, and it is sealed and stored to prepare aluminum nitride high-temperature co-fired pore-filling tungsten slurry.

[0013] Preferably, the organic solvent is one or a combination of acetone, ethanol, ethyl acetate, diethylene glycol ethyl ether acetate, and terpineol; the organic binder is one or a combination of ethyl cellulose and polyvinyl butyral; the dispersant is one or a combination of polyethylene glycol, oleic acid, trioleic acid glyceride, and fish oil; and the plasticizer is one or a combination of dimethyl phthalate and butyl benzyl phthalate.

[0014] Preferably, the viscosity of the aluminum nitride high-temperature co-fired pore-filling tungsten slurry is 400~500 Pa·s.

[0015] The beneficial effects of this invention are: This invention employs spray drying, calcination, and reduction processes to prepare tungsten-copper composite powder with a copper content of 10-30 wt.%. The tungsten-copper composite powder is then modified using an air-jet milling method. The air-jet milled tungsten-copper composite powder exhibits a narrower particle size distribution, smoother particle surfaces, and better powder dispersibility, which is beneficial for improving the packing density of the pores, enhancing the rheological properties of the slurry, and significantly reducing sintering shrinkage unevenness. Subsequently, a composite modified tungsten-copper composite powder is prepared by grafting a carboxyl-terminated hyperbranched polyester with γ-aminopropyltriethoxysilane onto the surface of the modified tungsten-copper composite powder, constructing an "organic-inorganic hybrid" system. The unique spherical dendritic structure of the hyperbranched polymer effectively prevents the agglomeration of the modified tungsten-copper composite powder, and the grafted modified tungsten-copper composite powder has better chemical affinity with the organic carrier, improving the rheological and thixotropic properties of the pore-filling slurry. Simultaneously, it effectively protects the modified tungsten-copper composite powder from oxidation during high-temperature co-firing. This invention achieves performance upgrades by optimizing the composition ratio and preparation process of tungsten paste. The tungsten paste is mainly composed of composite modified tungsten-copper composite powder, combined with a composite functional phase consisting of nano-aluminum-yttrium alloy powder and a low-temperature activation sintering aid, and an organic carrier. During high-temperature sintering, the nano-aluminum-yttrium alloy powder reacts in situ with residual oxygen to generate Al2O3 or YAG phase, effectively preventing oxidation damage to the tungsten-based conductor paste and aluminum nitride substrate. The low-temperature activation sintering aid significantly reduces the sintering activation energy and promotes the low-temperature densification sintering of the composite tungsten-copper powder. The synergistic effect of both eliminates harmful oxygen and... Low-temperature activation sintering was achieved, forming a continuous, dense, and high-bonding co-fired interface between the tungsten-based conductor paste and the aluminum nitride substrate. The scientifically proportioned components and their synergistic effects are significant. Gradient three-roll rolling and vacuum degassing processes improve the homogeneity of the paste. At the same time, process parameter control ensures product quality. This high-temperature co-fired aluminum nitride tungsten paste effectively solves the problems of easy oxidation, weak interface bonding, and poor pore filling effect of traditional products. It exhibits excellent sintering density, electrical conductivity, and mechanical properties. The preparation process is suitable for industrial production and can meet the application needs of aluminum nitride ceramic substrates in high-end electronic fields. Detailed Implementation

[0016] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0017] Example 1: A method for preparing a composite modified tungsten-copper composite powder includes the following steps: ① Add 1531g of ammonium paratungstate and 453g of copper nitrate to 5000mL of 90℃ deionized water and stir continuously. Add 330g of citric acid to promote the dissolution of ammonium paratungstate. After a uniform and transparent solution is formed, spray dry it. Set the air inlet temperature to 180℃, the atomizing disc speed to 18000rpm, and the feed rate to 3kg / h to obtain precursor powder. ② The precursor powder was calcined in air at 650°C for 4 hours to remove ammonium ions, nitrate ions and organic carbon from the precursor powder, and then reduced with hydrogen at 825°C for 5 hours to obtain tungsten-copper composite powder. ③ The tungsten-copper composite powder was modified by air jet crushing. The gas pressure was set to 0.7 MPa, the feed rate was set to 5 kg / h, and the classifier speed was set to 4200 rpm to prepare the modified tungsten-copper composite powder. ④ Take 2g of modified tungsten copper composite powder and ultrasonically disperse it in 80mL of ethanol. Then add 0.03g of γ-aminopropyltriethoxysilane, 20mL of deionized water and 20mL of ethanol. Stir ultrasonically for 2h. Then filter, wash and dry to prepare aminated modified tungsten copper composite powder. ⑤ Take 2g of aminated modified tungsten copper composite powder and ultrasonically disperse it in 80mL of acetone solvent. Then add 0.5% by mass of end-carboxyl hyperbranched polyester (hyperbranched polyester CHBP of model C102) and 0.002g of p-toluenesulfonic acid. Stir magnetically at 80℃ for 40min. Then filter, wash and dry to prepare the composite modified tungsten copper composite powder.

[0018] Example 2: A method for preparing a composite modified tungsten-copper composite powder includes the following steps: ① 1187.5g of ammonium paratungstate and 797g of copper nitrate were continuously stirred in 5000mL of 90℃ deionized water. 330g of citric acid was added to promote the dissolution of ammonium paratungstate. After a uniform and transparent solution was formed, spray drying was carried out. The air inlet temperature was set to 180℃, the atomizing disc speed was set to 18000rpm, and the feed rate was set to 3kg / h to obtain precursor powder. ② The precursor powder was calcined in air at 640℃ for 4.5h to remove ammonium ions, nitrate ions and organic carbon from the precursor powder, and then reduced with hydrogen at 800℃ for 6h to obtain tungsten copper composite powder. ③ The tungsten-copper composite powder was modified by airflow crushing. The gas pressure was set to 0.65 MPa, the feed rate was set to 4.5 kg / h, and the classifier speed was set to 4000 rpm to prepare the modified tungsten-copper composite powder. ④ Take 2g of modified tungsten copper composite powder and ultrasonically disperse it in 80mL of ethanol. Then add 0.03g of γ-aminopropyltriethoxysilane, 20mL of deionized water and 20mL of ethanol. Stir ultrasonically for 2h. Then filter, wash and dry to prepare aminated modified tungsten copper composite powder. ⑤ Take 2g of aminated modified tungsten copper composite powder and ultrasonically disperse it in 80mL of acetone solvent. Then add 0.5% by mass of end-carboxyl hyperbranched polyester (hyperbranched polyester CHBP of model C102) and 0.002g of p-toluenesulfonic acid. Stir magnetically at 80℃ for 40min. Then filter, wash and dry to prepare the composite modified tungsten copper composite powder.

[0019] Example 3: A method for preparing a composite modified tungsten-copper composite powder includes the following steps: ① 923g of ammonium paratungstate and 1061g of copper nitrate were continuously stirred in 5000mL of 90℃ deionized water. 330g of citric acid was added to promote the dissolution of ammonium paratungstate. After a uniform and transparent solution was formed, spray drying was carried out. The air inlet temperature was set to 180℃, the atomizing disc speed was set to 18000rpm, and the feed rate was set to 3kg / h to obtain precursor powder. ② The precursor powder was calcined in air at 660℃ for 4.5h to remove ammonium ions, nitrate ions and organic carbon from the precursor powder, and then reduced with hydrogen at 875℃ for 4h to obtain tungsten copper composite powder. ③ The tungsten-copper composite powder was modified by airflow crushing. The gas pressure was set to 0.6 MPa, the feed rate was set to 4.5 kg / h, and the classifier speed was set to 4000 rpm to prepare the modified tungsten-copper composite powder. ④ Take 2g of modified tungsten copper composite powder and ultrasonically disperse it in 80mL of ethanol. Then add 0.03g of γ-aminopropyltriethoxysilane, 20mL of deionized water and 20mL of ethanol. Stir ultrasonically for 2h. Then filter, wash and dry to prepare aminated modified tungsten copper composite powder. ⑤ Take 2g of aminated modified tungsten copper composite powder and ultrasonically disperse it in 80mL of acetone solvent. Then add 0.5% by mass of end-carboxyl hyperbranched polyester (hyperbranched polyester CHBP of model C102) and 0.002g of p-toluenesulfonic acid. Stir magnetically at 80℃ for 40min. Then filter, wash and dry to prepare the composite modified tungsten copper composite powder.

[0020] Example 4 A high-temperature co-fired aluminum nitride pore-filling tungsten slurry comprises the following components by mass percentage: 78% of the composite modified tungsten-copper composite powder prepared in Example 1, 14% of the composite functional phase, and 8% of the organic carrier.

[0021] The preparation method of the above-mentioned high-temperature co-fired aluminum nitride tungsten paste for filling holes includes the following steps: S1. Preparation of organic carrier: Add 0.4g ethyl cellulose and 0.2g polyvinyl butyral to 15mL terpineol in batches to dissolve, then add 0.2mL polyethylene glycol and 0.1mL dimethyl phthalate in sequence, stir at 70℃ until completely dissolved, keep warm for 2h, cool and filter to obtain organic carrier. S2. Preparation of slurry precursor: The composite modified tungsten copper composite powder and composite functional phase prepared in Example 1 are added to the mixing equipment and dry premixed for 30 min under argon protection. After thorough mixing, the mixture is added to the organic carrier and stirred for another 30 min to obtain the slurry precursor. The composite functional phase is composed of nano aluminum-yttrium alloy powder and SiO2-CuO-TiO2 in a mass ratio of 1:2. S3. Homogenization rolling on a three-roll mill: The initial slurry is added to a three-roll mill for repeated rolling. The initial gap between the rolls is 120µm, and the gap is gradually reduced to 15µm. The total number of rolling passes is 20 to obtain a homogeneous slurry. S4. Degassing and Storage: The homogeneous slurry is transferred to a vacuum degassing device, the vacuum degree is set to -0.09MPa, the degassing time is 30min, and after degassing, it is filtered. After filtration, the slurry is put into a sealed container, argon gas is introduced into the container, and it is sealed and stored to prepare aluminum nitride high-temperature co-fired pore-filling tungsten slurry.

[0022] Example 5 A high-temperature co-fired aluminum nitride pore-filling tungsten slurry comprises the following components by mass percentage: 79% of the composite modified tungsten-copper composite powder prepared in Example 2, 11% of the composite functional phase, and 10% of the organic carrier.

[0023] The preparation method of the above-mentioned high-temperature co-fired aluminum nitride tungsten paste for filling holes includes the following steps: S1. Preparation of organic carrier: Add 0.4g ethyl cellulose and 0.2g polyvinyl butyral to 15mL terpineol in batches to dissolve, then add 0.2mL polyethylene glycol and 0.1mL dimethyl phthalate in sequence, stir at 70℃ until completely dissolved, keep warm for 2h, cool and filter to obtain organic carrier. S2. Preparation of the initial slurry: The composite modified tungsten-copper composite powder and the composite functional phase prepared in Example 2 were added to the mixing equipment and dry premixed for 30 min under argon protection. After thorough mixing, the mixture was added to the organic carrier and stirred for another 30 min to obtain the initial slurry. The composite functional phase was composed of nano-aluminum-yttrium alloy powder and SiO2-CuO-TiO2 in a mass ratio of 1:3. S3. Homogenization rolling on a three-roll mill: The initial slurry is added to a three-roll mill for repeated rolling. The initial gap between the rolls is 120µm, and the gap is gradually reduced to 15µm. The total number of rolling passes is 20 to obtain a homogeneous slurry. S4. Degassing and Storage: The homogeneous slurry is transferred to a vacuum degassing device, the vacuum degree is set to -0.09MPa, the degassing time is 30min, and after degassing, it is filtered. After filtration, the slurry is put into a sealed container, argon gas is introduced into the container, and it is sealed and stored to prepare aluminum nitride high-temperature co-fired pore-filling tungsten slurry.

[0024] Example 6 A high-temperature co-fired aluminum nitride pore-filling tungsten slurry comprises the following components by mass percentage: 81% of the composite modified tungsten-copper composite powder prepared in Example 3, 10% of the composite functional phase, and 9% of the organic carrier.

[0025] The preparation method of the above-mentioned high-temperature co-fired aluminum nitride tungsten paste for filling holes includes the following steps: S1. Preparation of organic carrier: Add 0.4g ethyl cellulose and 0.2g polyvinyl butyral to 15mL terpineol in batches to dissolve, then add 0.2mL polyethylene glycol and 0.1mL dimethyl phthalate in sequence, stir at 70℃ until completely dissolved, keep warm for 2h, cool and filter to obtain organic carrier. S2. Preparation of slurry precursor: The composite modified tungsten copper composite powder and composite functional phase prepared in Example 3 are added to the mixing equipment and dry premixed for 30 min under argon protection. After thorough mixing, the mixture is added to the organic carrier and stirred for another 30 min to obtain the slurry precursor. The composite functional phase is composed of nano aluminum-yttrium alloy powder and SiO2-CuO-TiO2 in a mass ratio of 1:4. S3. Homogenization rolling on a three-roll mill: The initial slurry is added to a three-roll mill for repeated rolling. The initial gap between the rolls is 120µm, and the gap is gradually reduced to 15µm. The total number of rolling passes is 20 to obtain a homogeneous slurry. S4. Degassing and Storage: The homogeneous slurry is transferred to a vacuum degassing device, the vacuum degree is set to -0.09MPa, the degassing time is 30min, and after degassing, it is filtered. After filtration, the slurry is put into a sealed container, argon gas is introduced into the container, and it is sealed and stored to prepare aluminum nitride high-temperature co-fired pore-filling tungsten slurry.

[0026] Comparative Example 1: A high-temperature co-fired aluminum nitride pore-filling tungsten slurry comprises the following components by mass percentage: 79% tungsten-copper composite powder prepared in Example 2, 11% composite functional phase, and 10% organic carrier.

[0027] The preparation method of the above-mentioned high-temperature co-fired aluminum nitride tungsten paste for filling holes includes the following steps: S1. Preparation of organic carrier: Add 0.4g ethyl cellulose and 0.2g polyvinyl butyral to 15mL terpineol in batches to dissolve, then add 0.2mL polyethylene glycol and 0.1mL dimethyl phthalate in sequence, stir at 70℃ until completely dissolved, keep warm for 2h, cool and filter to obtain organic carrier. S2. Preparation of slurry precursor: The tungsten-copper composite powder and composite functional phase prepared in Example 2 are added to the mixing equipment and dry premixed for 30 min under argon protection. After thorough mixing, the mixture is added to the organic carrier and stirred for another 30 min to obtain the slurry precursor. The composite functional phase is composed of nano-aluminum-yttrium alloy powder and SiO2-CuO-TiO2 in a mass ratio of 1:3. S3. Homogenization rolling on a three-roll mill: The initial slurry is added to a three-roll mill for repeated rolling. The initial gap between the rolls is 120µm, and the gap is gradually reduced to 15µm. The total number of rolling passes is 20 to obtain a homogeneous slurry. S4. Degassing and Storage: The homogeneous slurry is transferred to a vacuum degassing device, the vacuum degree is set to -0.09MPa, the degassing time is 30min, and after degassing, it is filtered. After filtration, the slurry is put into a sealed container, argon gas is introduced into the container, and it is sealed and stored to prepare aluminum nitride high-temperature co-fired pore-filling tungsten slurry.

[0028] Comparative Example 2: A high-temperature co-fired aluminum nitride pore-filling tungsten slurry comprises the following components by mass percentage: 79% of the modified tungsten-copper composite powder prepared in Example 2, 11% of the composite functional phase, and 10% of the organic carrier.

[0029] The preparation method of the above-mentioned high-temperature co-fired aluminum nitride tungsten paste for filling holes includes the following steps: S1. Preparation of organic carrier: Add 0.4g ethyl cellulose and 0.2g polyvinyl butyral to 15mL terpineol in batches to dissolve, then add 0.2mL polyethylene glycol and 0.1mL dimethyl phthalate in sequence, stir at 70℃ until completely dissolved, keep warm for 2h, cool and filter to obtain organic carrier. S2. Preparation of slurry precursor: The modified tungsten copper composite powder and composite functional phase prepared in Example 2 are added to the mixing equipment and dry premixed for 30 min under argon protection. After thorough mixing, the mixture is added to the organic carrier and stirred for another 30 min to obtain the slurry precursor. The composite functional phase is composed of nano-aluminum-yttrium alloy powder and SiO2-CuO-TiO2 in a mass ratio of 1:3. S3. Homogenization rolling on a three-roll mill: The initial slurry is added to a three-roll mill for repeated rolling. The initial gap between the rolls is 120µm, and the gap is gradually reduced to 15µm. The total number of rolling passes is 20 to obtain a homogeneous slurry. S4. Degassing and Storage: The homogeneous slurry is transferred to a vacuum degassing device, the vacuum degree is set to -0.09MPa, the degassing time is 30min, and after degassing, it is filtered. After filtration, the slurry is put into a sealed container, argon gas is introduced into the container, and it is sealed and stored to prepare aluminum nitride high-temperature co-fired pore-filling tungsten slurry.

[0030] Comparative Example 3: A high-temperature co-fired aluminum nitride pore-filling tungsten slurry comprises the following components by mass percentage: 79% modified tungsten-copper composite powder prepared in Example 2, 11% composite functional phase, and 10% organic carrier.

[0031] The preparation method of the above-mentioned high-temperature co-fired aluminum nitride tungsten paste for filling holes includes the following steps: S1. Preparation of organic carrier: Add 0.4g ethyl cellulose and 0.2g polyvinyl butyral to 15mL terpineol in batches to dissolve, then add 0.2mL polyethylene glycol and 0.1mL dimethyl phthalate in sequence, stir at 70℃ until completely dissolved, keep warm for 2h, cool and filter to obtain organic carrier. S2. Preparation of slurry precursor: The modified tungsten copper composite powder and the composite functional phase SiO2-CuO-TiO2 prepared in Example 2 were added to the mixing equipment and dry premixed for 30 min under argon protection. After thorough mixing, the mixture was added to the organic carrier and stirred for another 30 min to obtain the slurry precursor. S3. Homogenization rolling on a three-roll mill: The initial slurry is added to a three-roll mill for repeated rolling. The initial gap between the rolls is 120µm, and the gap is gradually reduced to 15µm. The total number of rolling passes is 20 to obtain a homogeneous slurry. S4. Degassing and Storage: The homogeneous slurry is transferred to a vacuum degassing device, the vacuum degree is set to -0.09MPa, the degassing time is 30min, and after degassing, it is filtered. After filtration, the slurry is put into a sealed container, argon gas is introduced into the container, and it is sealed and stored to prepare aluminum nitride high-temperature co-fired pore-filling tungsten slurry.

[0032] Performance testing The composite modified tungsten-copper powders prepared in Examples 1-3 were subjected to cold isostatic pressing and medium-frequency induction sintering. The cold isostatic pressing was performed with a pressing force of 200 MPa and a holding time of 5 min. The compacts were then placed in a medium-frequency induction furnace for sintering under a hydrogen atmosphere throughout the process. The maximum sintering temperature was 2000℃, and the holding time was 2 h. The density of the sintered samples was determined using the Archimedes displacement method. A WDW-50 universal testing machine was used to perform a three-point flexural strength test on the sintered samples at room temperature. The sample dimensions were 3 mm × 3 mm × 21 mm, with a span of 10 mm. The sample surface was mechanically polished to a bright finish before testing. The data results are shown in the table below.

[0033] As can be seen from the data in the table above, the modified tungsten-copper composite powders prepared in Examples 1-3 of this invention have good sintering density and mechanical properties.

[0034] The aluminum nitride high-temperature co-fired tungsten pastes prepared in Examples 4-6 and Comparative Examples 1-3 were uniformly coated onto the surface of aluminum nitride green ceramic sheets with a thickness of 200 μm using a screen printing process. The thickness of the printed film was controlled at 20 μm. After drying, the printed green ceramic sheets were laminated using a double-layer lamination process to ensure uniform and tight lamination. The laminated green sheets were cut into several 35 mm × 26 mm strip samples and placed in a high-temperature sintering furnace for sintering in a wet hydrogen / nitrogen mixed atmosphere. The dimensions of the sintered samples were approximately 29 mm × 22 mm × 0.41 mm. The heating rate was controlled at 1 °C / min during sintering, the co-firing temperature was set at 1580 °C, and the temperature was held for 2 hours. Afterward, the samples were naturally cooled to room temperature, and the following performance tests were performed: The bonding strength of the slurry film layer was determined using the cross-cut adhesion test. First, the surface of the slurry film layer was ensured to be clean and uncontaminated. Then, the sample was placed flat on a table, and an 11-blade blade with 1mm spacing was used to make 11 horizontal rows of scratches along the slurry film layer, followed by 11 vertical rows of scratches, forming a 10×10 grid pattern on the film surface. The scratched surface was then completely covered with 3M tape, appropriate pressure was applied, and then the surface was quickly pulled up. The sheet resistance of the slurry film layer was tested using a four-probe sheet resistance tester to evaluate its conductivity. The data results are shown in the table below.

[0035] As can be seen from the data in the table above, since the composite modified tungsten copper composite powder was replaced with an equal amount of tungsten copper composite powder in Comparative Example 1, the composite modified tungsten copper composite powder was replaced with an equal amount of modified tungsten copper composite powder in Comparative Example 2, and no nano-aluminum-yttrium alloy powder was added in Comparative Example 3, the measured bonding strength of Comparative Examples 1-3 was lower than that of Examples 4-6, and the sheet resistance was higher than that of Examples 4-6. This indicates that the aluminum nitride high-temperature co-fired pore-filling tungsten slurry prepared in Examples 4-6 of this invention has better interfacial bonding strength and conductivity than Comparative Examples 1-3.

[0036] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0037] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A high-temperature co-fired aluminum nitride tungsten paste for filling pores, characterized in that, By mass percentage, it comprises the following components: 78-82% composite modified tungsten-copper composite powder, 10-14% composite functional phase, and 7-11% organic carrier; The modified tungsten-copper composite powder is prepared by spray drying, calcination and reduction processes to obtain tungsten-copper composite powder with a copper content of 10~30 wt.%, and modified by airflow crushing method. Then, it is grafted onto the surface of the prepared modified tungsten-copper composite powder using terminal carboxyl hyperbranched polyester in synergy with γ-aminopropyltriethoxysilane.

2. The aluminum nitride high-temperature co-fired tungsten paste for filling pores according to claim 1, characterized in that, The composite functional phase is composed of nano-aluminum-yttrium alloy powder and low-temperature activated sintering aid in a mass ratio of 1:2~4.

3. The aluminum nitride high-temperature co-fired tungsten paste for filling pores according to claim 2, characterized in that, The aluminum-yttrium atomic ratio in the nano-aluminum-yttrium alloy powder is 3:1; the low-temperature activation sintering aid is SiO2-CuO-TiO2.

4. The aluminum nitride high-temperature co-fired tungsten paste for filling pores according to claim 1, characterized in that, The preparation method of the composite modified tungsten-copper composite powder includes the following steps: ① Ammonium paratungstate and copper nitrate were continuously stirred in deionized water at 90℃. An appropriate amount of citric acid was added to promote the dissolution of ammonium paratungstate. After a uniform and transparent solution was formed, it was spray-dried to obtain precursor powder. ② The precursor powder is calcined in air at 600~700℃ to remove ammonium ions, nitrate ions and organic carbon from the precursor powder, and then reduced with hydrogen at 750~900℃ to obtain tungsten copper composite powder. ③ The tungsten-copper composite powder was modified by airflow crushing to obtain modified tungsten-copper composite powder; ④ The modified tungsten copper composite powder was ultrasonically dispersed in ethanol, and then a mixed solution of γ-aminopropyltriethoxysilane, deionized water and ethanol was added. The mixture was ultrasonically stirred for 2 hours, and then filtered, washed and dried to prepare the aminated modified tungsten copper composite powder. ⑤ The aminated modified tungsten-copper composite powder was ultrasonically dispersed in acetone solvent, and then 0.5% by mass of terminal carboxyl hyperbranched polyester and p-toluenesulfonic acid were added. The mixture was then magnetically stirred at 80~100℃ for 30~40 min, and subsequently filtered, washed and dried to prepare the composite modified tungsten-copper composite powder.

5. The aluminum nitride high-temperature co-fired tungsten paste for filling pores according to claim 4, characterized in that, The inlet temperature of the spray dryer is set to 180℃, the rotation speed of the atomizing disc is set to 18000rpm, and the feeding speed is set to 3kg / h; the copper content in the tungsten-copper composite powder is 10~30wt.%.

6. The aluminum nitride high-temperature co-fired pore-filling tungsten paste according to claim 4, characterized in that, The gas pressure for the airflow crusher is set to 0.5~0.7MPa, the feed rate is set to 4.5~5kg / h, and the classifier wheel speed is set to 4000~4200rpm.

7. The aluminum nitride high-temperature co-fired tungsten paste for filling pores according to claim 4, characterized in that, The particle size parameter of the modified tungsten-copper composite powder is: D 10 The thickness is 1.15~1.25μm, D 50 The diameter is 2.55~2.65μm, D 90 The thickness is 4.55~4.67μm.

8. The method for preparing high-temperature co-fired aluminum nitride tungsten paste for filling pores according to any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Preparation of organic carrier: Organic binder is added to organic solvent in batches to dissolve it, then dispersant and plasticizer are added in sequence, heated and stirred evenly, cooled and filtered to obtain organic carrier; S2. Preparation of slurry precursor: Take the composite modified tungsten copper composite powder and composite functional phase and add them to the mixing equipment. Dry premix for 30 min under argon protection. After thorough mixing, add them to the organic carrier and continue stirring for 30 min to obtain the slurry precursor. S3. Homogenization rolling on a three-roll mill: The initial slurry is added to a three-roll mill for repeated rolling. The initial gap between the rolls is 120µm, and the gap is gradually reduced to 15µm. The total number of rolling passes is 20 to obtain a homogeneous slurry. S4. Degassing and Storage: The homogeneous slurry is transferred to a vacuum degassing device, the vacuum degree is set to -0.09MPa, the degassing time is 30min, and after degassing, it is filtered. After filtration, the slurry is put into a sealed container, argon gas is introduced into the container, and it is sealed and stored to prepare aluminum nitride high-temperature co-fired pore-filling tungsten slurry.

9. The method for preparing high-temperature co-fired aluminum nitride tungsten slurry for filling pores according to claim 8, characterized in that, The organic solvent is one or a combination of acetone, ethanol, ethyl acetate, diethylene glycol ethyl ether acetate, and terpineol; the organic binder is one or a combination of ethyl cellulose and polyvinyl butyral; the dispersant is one or a combination of polyethylene glycol, oleic acid, trioleic acid glyceride, and fish oil; and the plasticizer is one or a combination of dimethyl phthalate and butyl benzyl phthalate.

10. The method for preparing high-temperature co-fired aluminum nitride tungsten paste for filling pores according to claim 8, characterized in that, The viscosity of the aluminum nitride high-temperature co-fired pore-filling tungsten slurry is 400~500 Pa·s.

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