Aluminum nitride tape casting slurry based on double dispersing agents and preparation method

Abstract

The invention relates to the field of advanced ceramic materials, in particular to aluminum nitride tape casting slurry based on double dispersants and a preparation method, raw materials comprise standby materials and dispersants, the standby materials comprise aluminum nitride powder, a solvent, a binder and a plasticizer, and the dispersants comprise low-polarity dispersants and high-polarity dispersants. According to the invention, a double-dispersant system is adopted, a low-polarity dispersant reacts with Al-O and Al-OH bonds, a certain anchoring foundation is provided for a high-polarity dispersant, and a foundation for the stability of the whole chemical system is also laid. The high-polarity dispersing agent reacts with an Al-N bond on the surface of the powder, the high-polarity dispersing agent is a block copolymer, partially provides an anchoring chain, partially provides solvation and provides a strong steric hindrance effect, and under the synergistic effect of the high-polarity dispersing agent and the block copolymer, the dispersing efficiency and the system stability are remarkably improved; therefore, the film forming quality of the tape casting slurry and the compactness and thermal conductivity of a sintered body are remarkably improved.

Description

TECHNICAL FIELD

[0001] The application relates to the field of advanced ceramic materials, in particular to an aluminum nitride tape casting slurry based on a double dispersant and a preparation method. BACKGROUND

[0002] Aluminum nitride ceramics are widely used in electronic packaging fields such as power devices, IGBT modules and high-frequency communications due to high thermal conductivity, electrical insulation and thermal expansion coefficient matching, and become an important material of high-performance ceramic substrates. Especially under the background of increasing demand for high heat flux density and high reliability, higher standards are put forward for its thermal conductivity and structural density.

[0003] The commonly used ceramic substrate materials at present include alumina, silicon nitride and aluminum nitride. Alumina has low thermal conductivity (<30 W / m·K), and silicon nitride is prone to lattice distortion during sintering, and both of them are difficult to meet the high-end heat dissipation demand. In comparison, aluminum nitride has a theoretical thermal conductivity as high as 320 W / m·K and good thermal expansion matching, and is an ideal next-generation heat dissipation ceramic material.

[0004] However, the aluminum nitride powder is prone to hydrolysis in air due to high surface activity, and Al-OH bonds are formed on the surface, the bond energy is large, and under the polarization effect, the agglomeration tendency is strong, and the slurry is prone to poor dispersion, poor flowability and other problems during preparation, which seriously affects the film formation and sintering density. Especially the high-polarity single dispersing system used in the traditional way, it is difficult to realize good wettability and steric hindrance at the same time, which limits the play of slurry solid content and thermal conductivity performance.

[0005] In the actual application process, we are faced with a pure aluminum nitride core-shell structure wrapped by amorphous alumina and aluminum hydroxide, therefore, the key to dispersing aluminum nitride powder is to handle the benign hydroxyl (Al-OH) group and Al-O bond on its surface. According to the above chemical analysis, it is difficult to achieve high uniform dispersion only by relying on the properties of aluminum nitride itself, and the aid of external substances (dispersants) is needed. The principle is to use the strong interaction between dispersants and Al-OH groups on the surface of the powder, i.e. electrostatic repulsion and steric hindrance, to overcome the van der Waals force between the powders, so as to achieve high dispersion.

[0006] The thermal conductivity of aluminum nitride ceramic is highly dependent on the continuity of the microstructure after sintering, which is affected by the dispersion uniformity of the slurry and the forming quality. Developing an aluminum nitride slurry system with high solid content, high dispersion stability and good fluidity is a key technical breakthrough to realize the industrial application of high thermal conductivity ceramic substrate. SUMMARY

[0007] The purpose of this invention is to overcome the above-mentioned technical defects and provide an aluminum nitride ceramic casting slurry with high dispersibility, high solid content and excellent flowability achieved by the synergistic effect of low polarity dispersant and high polarity dispersant, and its preparation method, thereby significantly improving the sintering density and thermal conductivity of ceramic substrates.

[0008] The objective of this invention is achieved through the following technical solution: In a first aspect, the present invention discloses an aluminum nitride casting slurry based on a dual dispersant. The raw materials include a pre-mixed material and a dispersant. The pre-mixed material includes 40wt%-55wt% aluminum nitride powder, 35wt%-45wt% solvent, 4wt%-8wt% binder, and 1wt%-2.5wt% plasticizer, totaling 100wt%. The dispersant includes a low-polarity dispersant comprising 0.5wt%-1wt% of the pre-mixed material and a high-polarity dispersant comprising 1.0wt%-2.5wt% of the pre-mixed material.

[0009] In the aluminum nitride ceramic casting slurry of this invention, the chemical state of the aluminum nitride powder surface is relatively complex. Although it only has pure Al-N bonds, it is extremely unstable in air and easily undergoes hydrolysis, producing a layer of hydrolysis products on the aluminum nitride surface, forming Al-OH bonds, Al-O bonds, NH bonds, and Al-N bonds extending on the powder particle surface. In a single dispersant system, a single dispersant cannot firmly adsorb onto the various active sites with different properties on the powder surface, easily leading to particle agglomeration, large viscosity fluctuations, and poor flowability, which has significant limitations, especially under high solids content conditions where stability is even worse. This invention adopts a dual dispersant system, where the low-polarity dispersant interacts with the Al-O and Al-OH bonds, also providing a certain anchoring basis for the high-polarity dispersant, and laying the foundation for the stability of the entire chemical system. The highly polar dispersant interacts with the Al-N bonds on the powder surface. As a block copolymer, the highly polar dispersant partially provides anchoring chains and partially provides solvation, providing a strong steric hindrance effect. The synergistic effect of both significantly improves dispersion efficiency and system stability.

[0010] Preferably, the low-polarity dispersant is oleic acid or SAGO 8080 additive.

[0011] Preferably, the highly polar dispersant is polyetherimide, BYK111 additive, or SAGO9780 additive.

[0012] Preferably, the solvent is at least two of ethanol, toluene, xylene, and acetone.

[0013] Preferably, the solvent is a mixture of ethanol and toluene, preferably, the mass ratio of ethanol to toluene is 1:1-7:3, and preferably, the mass ratio of ethanol to toluene is 7:3.

[0014] Preferably, the adhesive is at least one of polyvinyl butyral, propylene resin, cellulose derivative, and polystyrene, and the plasticizer is at least one of polyethylene glycol and phthalate. Preferably, the polyethylene glycol is polyethylene glycol 200 and / or polyethylene glycol 400.

[0015] Preferably, the adhesive is polyvinyl butyral and the plasticizer is polyethylene glycol 200.

[0016] Preferably, the aluminum nitride powder has an average particle size D50 of 1-1.5 μm.

[0017] Secondly, this invention discloses a method for preparing the aluminum nitride casting slurry based on a dual dispersant, comprising the following steps: (1) Mix the solvent, binder and plasticizer evenly to prepare a uniform organic solvent carrier; (2) Add aluminum nitride powder and wet grind it into a slurry; (3) Add the low-polarity dispersant to the slurry and continue ball milling; (4) Add a high polarity dispersant to the system and continue ball milling to obtain the aluminum nitride casting slurry based on the dual dispersant.

[0018] Preferably, in step (2), a ball mill is used for wet milling, the mass ratio of balls to powder is 1-2:1, the ball milling speed is 200-300 rpm, and the wet milling time is 1-2 hours.

[0019] Preferably, in step (3), the specific process is as follows: dissolve the low polarity dispersant in a small amount of solvent, add it to the slurry, and ball mill at 400-500 rpm for 2-4 hours; In step (4), the ball milling speed is 300-400 rpm and the ball milling time is 2-4 hours.

[0020] Preferably, the process further includes a molding step: after degassing the slurry obtained in step (4), the slurry is cast and dried to obtain a green ceramic tape with a thickness of about 100–150 μm, which is used for subsequent sintering and molding; the casting parameters are: the scraper height is set to 300–500 μm, the casting speed is 0.1 m / min, and after casting, the tape is subjected to gradient drying at 35–55℃ for 60–80 min to obtain a green ceramic tape with a thickness of about 100–150 μm, which is used for subsequent cutting and stacking of samples, warm isostatic pressing, degreasing, sintering and performance characterization of the samples.

[0021] Preferably, the gradient drying process involves setting each temperature gradient to 10°C and drying at each temperature for 20 minutes. This invention employs a gradient drying process, which allows solvent components to evaporate in layers, ensuring uniform drying of the green body and preventing cracking.

[0022] The low-polarity dispersants (oleic acid, Sago8080) in this invention are typical long-chain fatty acids with good wetting and interfacial activity. For example, oleic acid, as a nonpolar organic solvent system, has a carboxyl functional group (-COOH) that can adsorb onto the powder surface, improving compatibility with the dispersion medium. Its long carbon chain provides steric stability, effectively inhibiting initial agglomeration. Similarly, Sago8080, in addition to containing a carboxyl functional group (-COOH), also has carbon-carbon double bonds (C=C), which can react with Al... 3+ To form stable coordination compounds, the two dispersants primarily target the Al-O and Al-OH bonds present on the surface of aluminum nitride powder. For the Al-N bonds present on the aluminum nitride powder surface, a highly polar dispersant (PEI, BYK111, or Sago9780) is required. This highly polar dispersant exists as a block copolymer, containing phosphate groups that strongly interact with the Al-N bonds. The anchoring groups of the dispersant are firmly adsorbed onto the powder surface, and the solvated segments extend into the solvent, forming a protective layer that prevents particles from approaching each other while providing stable steric stability. Its segmental structure can also regulate the rheological behavior of the system under shear stress, giving the slurry good shear dilution properties and storage stability.

[0023] When the two types of dispersants are used in combination, efficient dispersion and system stability of powders under high solid content conditions can be achieved, thereby significantly improving the film-forming quality of the cast slurry and the density and thermal conductivity of the sintered body.

[0024] Compared with the prior art, the present invention has the following advantages and effects: The aluminum nitride ceramic casting slurry of this invention overcomes the limitations of a single dispersant system. Traditional ceramic slurries often use highly polar dispersants that act directly on the powder. However, due to their large structure and limited adsorption sites, these dispersants cannot easily break the Al-O bonds on the powder surface, easily leading to the formation of Al-O-Al bonds. This results in particle agglomeration in the colloid, making dispersion difficult, causing high viscosity and poor flowability, and exhibiting particularly insufficient stability under high solids content conditions. This invention employs a dual dispersant system, significantly improving dispersion efficiency and system stability.

[0025] The aluminum nitride ceramic casting slurry of this invention uses a low-polarity dispersant containing carboxyl groups (-COOH) or carbon-carbon double bonds (C=C), which can react with the Al in the highly active Al-O bonds on the surface of aluminum nitride. 3+The formation of coordination compounds can also provide an anchoring basis for the high polarity of the block copolymer. Meanwhile, low-polarity molecules in the organic system of aluminum nitride ceramic casting slurry exhibit weak electrostatic forces between particles, making it difficult to maintain the stability of the entire system. Simultaneously, the hydroxyl groups (-OH) on the surface of aluminum nitride easily form hydrogen bonds, leading to inter-particle bonding and difficulty in dispersing the powder particles. Considering these factors, a block polymer molecule with high polarity dispersant is used. This molecule forms a strong interaction with the Al-N bonds on the surface of the aluminum nitride powder in the form of anchoring groups. The anchoring groups of the dispersant adsorb onto the powder surface, and the solvated chains extend into the solvent to form a protective layer, preventing particle aggregation. At the same time, the high-polarity chains also provide a strong steric hindrance effect, which is beneficial to the stability of the entire slurry system and is a crucial step in the preparation of high thermal conductivity aluminum nitride ceramic substrates.

[0026] In summary, when the two types of dispersants are used synergistically, the different structural sites on the surface of aluminum nitride, which are bonded or coordinated by dispersants of different polar molecular weights, not only solve the problem of difficult powder dispersion, but also achieve the stability of the entire slurry system. Under the synergistic effect of the two, efficient dispersion of powder and system stability are achieved under high solid content conditions, thereby significantly improving the film-forming quality of the cast slurry and the density and thermal conductivity of the sintered body.

[0027] The preparation method of the present invention is simple and easy to adjust. With the raw materials of the present invention, the final aluminum nitride cast blank has a dense structure and the thermal conductivity after sintering can stably reach more than 230 W / m·K. Attached Figure Description

[0028] Figure 1 This is a TEM image of the surface of the aluminum nitride powder of the present invention; Figure 2 The image shows a SEM image of the green body prepared using the bi-dispersants Sago8080 and Sago9780 in Example 16 of this invention. Figure 3 This is a SEM image of the green body prepared using a single dispersant, the highly polar Sago9780, in Comparative Example 4 of this invention. Figure 4 This is a SEM image of the green body prepared using a single dispersant, low polarity Sago8080, in Comparative Example 3 of this invention. Figure 5 The images show SEM images of sintered bodies prepared using different solvent ratios of the same proportion of bidispersant (Sago8080-0.5wt% and Sago9780-1.5wt%) in Examples 3, 6 and 9 of this invention, where (a) is Example 3, (b) is Example 6 and (c) is Example 9. Figure 6SEM images of sintered bodies prepared using different proportions of bidispersants (Sago8080 and Sago9780) in solvents of the same ratio (ethanol + toluene = 7:3) in Examples 13, 14, 15, and 16 of this invention are shown, where (a) is Example 13, (b) is Example 14, (c) is Example 15, and (d) is Example 16. Figure 7 The images show SEM images of sintered bodies prepared using different solvent systems with the same proportion of a single dispersant in Comparative Examples 3, 4, 7, and 8 of this invention, where (a) is Comparative Example 3, (b) is Comparative Example 4, (c) is Comparative Example 7, and (d) is Comparative Example 8. Detailed Implementation

[0029] To better understand the present invention, the following embodiments are further illustrations of the present invention, but the content of the present invention is not limited to the following embodiments.

[0030] Unless otherwise specified, the methods described in the following examples are conventional; the reagents and materials described are commercially available unless otherwise specified.

[0031] Figure 1 This is a TEM image of the surface of the aluminum nitride powder of the present invention. As can be seen from the image, the chemical state of the aluminum nitride powder surface is relatively complex. Although it only has pure Al-N bonds, it is extremely unstable in air and easily undergoes hydrolysis, producing a layer of hydrolysis products on the aluminum nitride surface, forming Al-OH bonds, Al-O bonds, NH bonds and Al-N bonds extending on the surface of the powder particles.

[0032] Example 1 A bi-dispersant-based aluminum nitride casting slurry comprises a pre-mixed material and a dispersant. The pre-mixed material includes the following components: 50 wt% aluminum nitride powder, 41 wt% solvent (a mixed solvent of ethanol and toluene in a mass ratio of 7:3), 7 wt% polyvinyl butyral, and 2 wt% polyethylene glycol 200. The dispersant comprises 0.5 wt% oleic acid and 1.5 wt% BYK 111 additive.

[0033] The preparation method of the aluminum nitride casting slurry based on a bi-dispersant includes the following steps: 1) Solvent system preparation: Add PVB (polyvinyl butyral) and PEG 200 (polyethylene glycol 200) to the solvent, stir at 200 rpm for 30 min.

[0034] 2) Pretreatment of main material powder: Add AlN powder (D50=1-1.5μm) to the solvent system in step 1), with a ball-to-powder ratio of 2:1, and ball mill at 200rpm for 1.5h.

[0035] 3) Low polarity dispersant: Dissolve oleic acid in a small amount of solvent, and then slowly add it dropwise to the slurry obtained in step 2), and ball mill at 400 rpm for 2 h.

[0036] 4) High polarity dispersant: Add BYK 111 additive to step 3 and ball mill at 300 rpm for 4 h.

[0037] 5) Degassing and casting: Degas the slurry mixed in step 4) under vacuum for 30 min, cast to a thickness of 500 μm at a casting speed of 0.1 m / min, and then dry at 35℃ for 25 min, 45℃ for 25 min, and 55℃ for 25 min in sequence.

[0038] 6) Sintering: Sinter at 1850℃ for 3 hours in a nitrogen atmosphere.

[0039] Example 2 A bi-dispersant-based aluminum nitride casting slurry, comprising a pre-mixed material and a dispersant, wherein the pre-mixed material comprises the following components: 50 wt% aluminum nitride powder, 41 wt% solvent (a mixed solvent of ethanol and toluene in a mass ratio of 7:3), 7 wt% polyvinyl butyral (PEI), and 2 wt% PEG 200; and the dispersant comprises 0.5 wt% oleic acid and 1.5 wt% polyetherimide.

[0040] The preparation method of the aluminum nitride casting slurry based on bi-dispersant includes the following steps: 1) Solvent system preparation: Add PVB (polyvinyl butyral) and PEG 200 (polyethylene glycol 200) to the solvent, stir at 200 rpm for 30 min.

[0041] 2) Pretreatment of main material powder: Add AlN powder (D50=1-1.5μm) to the solvent system in step 1), with a ball-to-powder ratio of 2:1, and ball mill at 200rpm for 1.5h.

[0042] 3) Low polarity dispersant: Dissolve oleic acid in a small amount of solvent, and then slowly add it dropwise to the slurry obtained in step 2), and ball mill at 400 rpm for 2 h.

[0043] 4) High polarity dispersant: Add PEI additive to step 3 and ball mill at 300 rpm for 4 h.

[0044] 5) Degassing and casting: Degas the slurry mixed in step 4) under vacuum for 30 min, cast to a thickness of 500 μm at a casting speed of 0.1 m / min, and then perform gradient drying at 35℃-55℃ for 75 min.

[0045] 6) Sintering: Sinter at 1850℃ for 3 hours in a nitrogen atmosphere.

[0046] Example 3 A bi-dispersant-based aluminum nitride casting slurry comprises a pre-mixed material and a dispersant. The pre-mixed material includes the following components: 50 wt% aluminum nitride powder, 41 wt% solvent (a mixed solvent of ethanol and toluene in a mass ratio of 7:3), 7 wt% polyvinyl butyral, and 2 wt% PEG 200. The dispersant comprises 0.5 wt% Shanggao Sago8080 and 1.5 wt% Shanggao Sago9780.

[0047] The preparation method of the aluminum nitride casting slurry based on a bi-dispersant includes the following steps: 1) Solvent system preparation: Add PVB (polyvinyl butyral) and PEG 200 (polyethylene glycol 200) to the solvent, stir at 200 rpm for 30 min.

[0048] 2) Pretreatment of main material powder: Add AlN powder (D50=1-1.5μm) to the solvent system in step 1), with a ball-to-powder ratio of 2:1, and ball mill at 200rpm for 1.5h.

[0049] 3) Low polarity dispersant: Dissolve Sago8080 in a small amount of solvent, then slowly add it dropwise to the slurry obtained in step 2), and ball mill at 400 rpm for 2 h.

[0050] 4) High polarity dispersant: Add Sago9780 to step 3 and ball mill at 300 rpm for 4 h.

[0051] 5) Degassing and casting: Degas the slurry mixed in step 4) under vacuum for 30 min, cast to a thickness of 500 μm at a casting speed of 0.1 m / min, and then perform gradient drying at 35℃-55℃ for 75 min.

[0052] 6) Sintering: Sinter at 1850℃ for 3 hours in a nitrogen atmosphere.

[0053] Example 4 A bi-dispersant-based aluminum nitride casting slurry comprises a pre-mixed material and a dispersant. The pre-mixed material includes the following components: 50 wt% aluminum nitride powder, 41 wt% solvent (a mixed solvent of ethanol and toluene in a mass ratio of 1:1), 7 wt% polyvinyl butyral, and 2 wt% polyethylene glycol 200. The dispersant includes 0.5 wt% oleic acid and 1.5 wt% BYK 111 additive.

[0054] The preparation method of the aluminum nitride casting slurry based on a bi-dispersant includes the following steps: 1) Solvent system preparation: Add PVB (polyvinyl butyral) and PEG 200 (polyethylene glycol 200) to the solvent, stir at 200 rpm for 30 min.

[0055] 2) Pretreatment of main material powder: Add AlN powder (D50=1-1.5μm) to the solvent system in step 1), with a ball-to-powder ratio of 2:1, and ball mill at 200rpm for 1.5h.

[0056] 3) Low polarity dispersant: Dissolve oleic acid in a small amount of solvent, and then slowly add it dropwise to the slurry obtained in step 2), and ball mill at 400 rpm for 2 h.

[0057] 4) High polarity dispersant: Add BYK 111 additive to step 3) and ball mill at 300 rpm for 4 h.

[0058] 5) Degassing and casting: Degas the slurry mixed in step 4) under vacuum for 30 min, cast to a thickness of 500 μm at a casting speed of 0.1 m / min, and then perform gradient drying at 35℃-55℃ for 75 min.

[0059] 6) Sintering: Sinter at 1850℃ for 3 hours in a nitrogen atmosphere.

[0060] Example 5 A bi-dispersant-based aluminum nitride casting slurry, comprising a pre-mixed material and a dispersant, wherein the pre-mixed material comprises the following components: 50 wt% aluminum nitride powder, 41 wt% solvent (a mixed solvent of ethanol and toluene in a mass ratio of 1:1), 7 wt% polyvinyl butyral (PEI), and 2 wt% PEG 200; and the dispersant comprises 0.5 wt% oleic acid and 1.5 wt% polyetherimide.

[0061] The preparation method of the aluminum nitride casting slurry based on a bi-dispersant includes the following steps: 1) Solvent system preparation: Add PVB (polyvinyl butyral) and PEG 200 (polyethylene glycol 200) to the solvent, stir at 200 rpm for 30 min.

[0062] 2) Pretreatment of main material powder: Add AlN powder (D50=1-1.5μm) to the solvent system in step 1), with a ball-to-powder ratio of 2:1, and ball mill at 200rpm for 1.5h.

[0063] 3) Low polarity dispersant: Dissolve oleic acid in a small amount of solvent, and then slowly add it dropwise to the slurry obtained in step 2), and ball mill at 400 rpm for 2 h.

[0064] 4) High polarity dispersant: Add PEI additive to step 3 and ball mill at 300 rpm for 4 h.

[0065] 5) Degassing and casting: Degas the slurry mixed in step 4) under vacuum for 30 min, cast to a thickness of 500 μm at a casting speed of 0.1 m / min, and then perform gradient drying at 35℃-55℃ for 75 min.

[0066] 6) Sintering: Sinter at 1850℃ for 3 hours in a nitrogen atmosphere.

[0067] Example 6 A bi-dispersant-based aluminum nitride casting slurry comprises a pre-mixed material and a dispersant. The pre-mixed material includes the following components: 50 wt% aluminum nitride powder, 41 wt% solvent (a mixed solvent of ethanol and toluene in a mass ratio of 1:1), 7 wt% polyvinyl butyral, and 2 wt% PEG 200. The dispersant comprises 0.5 wt% Shanggao Sago8080 and 1.5 wt% Shanggao Sago9780.

[0068] The preparation method of the aluminum nitride casting slurry based on a bi-dispersant includes the following steps: 1) Solvent system preparation: Add PVB (polyvinyl butyral) and PEG 200 (polyethylene glycol 200) to the solvent, stir at 200 rpm for 30 min.

[0069] 2) Pretreatment of main material powder: Add AlN powder (D50=1-1.5μm) to the solvent system in step 1), with a ball-to-powder ratio of 2:1, and ball mill at 200rpm for 1.5h.

[0070] 3) Low polarity dispersant: Dissolve Sago8080 in a small amount of solvent, then slowly add it dropwise to the slurry obtained in step 2), and ball mill at 400 rpm for 2 h.

[0071] 4) High polarity dispersant: Add Sago9780 to step 3 and ball mill at 300 rpm for 4 h.

[0072] 5) Degassing and casting: Degas the slurry mixed in step 4) under vacuum for 30 min, cast to a thickness of 500 μm at a casting speed of 0.1 m / min, and then perform gradient drying at 35℃-55℃ for 75 min.

[0073] 6) Sintering: Sinter at 1850℃ for 3 hours in a nitrogen atmosphere.

[0074] Example 7 A bi-dispersant-based aluminum nitride casting slurry comprises a pre-mixed material and a dispersant. The pre-mixed material includes the following components: 50 wt% aluminum nitride powder, 41 wt% solvent (a mixed solvent of ethanol and toluene in a mass ratio of 3:2), 7 wt% polyvinyl butyral, and 2 wt% polyethylene glycol 200. The dispersant comprises 0.5 wt% oleic acid and 1.5 wt% BYK 111 additive.

[0075] The preparation method of the aluminum nitride casting slurry based on a bi-dispersant includes the following steps: 1) Solvent system preparation: Add PVB (polyvinyl butyral) and PEG 200 (polyethylene glycol 200) to the solvent, stir at 200 rpm for 30 min.

[0076] 2) Pretreatment of main material powder: Add AlN powder (D50=1-1.5μm) to the solvent system in step 1), with a ball-to-powder ratio of 2:1, and ball mill at 200rpm for 1.5h.

[0077] 3) Low polarity dispersant: Dissolve oleic acid in a small amount of solvent, and then slowly add it dropwise to the slurry obtained in step 2), and ball mill at 400 rpm for 2 h.

[0078] 4) High polarity dispersant: Add BYK 111 additive to step 3) and ball mill at 300 rpm for 4 h.

[0079] 5) Degassing and casting: Degas the slurry mixed in step 4) under vacuum for 30 min, cast to a thickness of 500 μm at a casting speed of 0.1 m / min, and then perform gradient drying at 35℃-55℃ for 75 min.

[0080] 6) Sintering: Sinter at 1850℃ for 3 hours in a nitrogen atmosphere.

[0081] Example 8 A bi-dispersant-based aluminum nitride casting slurry comprises a pre-mixed material and a dispersant. The pre-mixed material includes the following components: 50 wt% aluminum nitride powder, 41 wt% solvent (a mixed solvent of ethanol and toluene in a mass ratio of 3:2), 7 wt% polyvinyl butyral (PEI), and 2 wt% PEG 200. The dispersant comprises 0.5 wt% oleic acid and 1.5 wt% polyetherimide.

[0082] The preparation method of the aluminum nitride casting slurry based on a bi-dispersant includes the following steps: 1) Solvent system preparation: Add PVB (polyvinyl butyral) and PEG 200 (polyethylene glycol 200) to the solvent, stir at 200 rpm for 30 min.

[0083] 2) Pretreatment of main material powder: Add AlN powder (D50=1-1.5μm) to the solvent system in step 1), with a ball-to-powder ratio of 2:1, and ball mill at 200rpm for 1.5h.

[0084] 3) Low polarity dispersant: Dissolve oleic acid in a small amount of solvent, and then slowly add it dropwise to the slurry obtained in step 2), and ball mill at 400 rpm for 2 h.

[0085] 4) High polarity dispersant: Add PEI additive to step 3 and ball mill at 300 rpm for 4 h.

[0086] 5) Degassing and casting: Degas the slurry mixed in step 4) under vacuum for 30 min, cast to a thickness of 500 μm at a casting speed of 0.1 m / min, and then perform gradient drying at 35℃-55℃ for 75 min.

[0087] 6) Sintering: Sinter at 1850℃ for 3 hours in a nitrogen atmosphere.

[0088] Example 9 A bi-dispersant-based aluminum nitride casting slurry comprises a pre-mixed material and a dispersant. The pre-mixed material includes the following components: 50 wt% aluminum nitride powder, 41 wt% solvent (a mixed solvent of ethanol and toluene in a mass ratio of 3:2), 7 wt% polyvinyl butyral, and 2 wt% PEG 200. The dispersant comprises 0.5 wt% Shanggao Sago8080 and 1.5 wt% Shanggao Sago9780.

[0089] The preparation method of the aluminum nitride casting slurry based on a bi-dispersant includes the following steps: 1) Solvent system preparation: Add PVB (polyvinyl butyral) and PEG 200 (polyethylene glycol 200) to the solvent, stir at 200 rpm for 30 min.

[0090] 2) Pretreatment of main material powder: Add AlN powder (D50=1-1.5μm) to the solvent system in step 1), with a ball-to-powder ratio of 2:1, and ball mill at 200rpm for 1.5h.

[0091] 3) Low polarity dispersant: Dissolve Sago8080 in a small amount of solvent, then slowly add it dropwise to the slurry obtained in step 2), and ball mill at 400 rpm for 2 h.

[0092] 4) High polarity dispersant: Add Sago9780 to step 3 and ball mill at 300 rpm for 4 h.

[0093] 5) Degassing and casting: Degas the slurry mixed in step 4) under vacuum for 30 min, cast to a thickness of 500 μm at a casting speed of 0.1 m / min, and then perform gradient drying at 35℃-55℃ for 75 min.

[0094] 6) Sintering: Sinter at 1850℃ for 3 hours in a nitrogen atmosphere.

[0095] Example 10 A bi-dispersant-based aluminum nitride casting slurry, comprising a pre-mixed material and a dispersant, wherein the pre-mixed material comprises the following components: 50 wt% aluminum nitride powder, 41 wt% a mixed solvent of ethanol and xylene in a mass ratio of 7:3, 7 wt% polyvinyl butyral, and 2 wt% PEG 200; the dispersant comprises 0.5 wt% Shanggao Sago8080 and 1.5 wt% Shanggao Sago9780.

[0096] The preparation method of the aluminum nitride casting slurry based on a bi-dispersant includes the following steps: 1) Solvent system preparation: Add PVB (polyvinyl butyral) and PEG 200 (polyethylene glycol 200) to the solvent, stir at 200 rpm for 30 min.

[0097] 2) Pretreatment of main material powder: Add AlN powder (D50=1-1.5μm) to the solvent system in step 1), with a ball-to-powder ratio of 2:1, and ball mill at 200rpm for 1.5h.

[0098] 3) Low polarity dispersant: Dissolve Sago8080 in a small amount of solvent, then slowly add it dropwise to the slurry obtained in step 2), and ball mill at 400 rpm for 2 h.

[0099] 4) High polarity dispersant: Add Sago9780 to step 3 and ball mill at 300 rpm for 4 h.

[0100] 5) Degassing and casting: Degas the slurry mixed in step 4) under vacuum for 30 min, cast to a thickness of 500 μm at a casting speed of 0.1 m / min, and then perform gradient drying at 35℃-55℃ for 75 min.

[0101] 6) Sintering: Sinter at 1850℃ for 3 hours in a nitrogen atmosphere.

[0102] Example 11 A bi-dispersant-based aluminum nitride casting slurry, comprising a pre-mixed material and a dispersant, wherein the pre-mixed material comprises the following components: 50 wt% aluminum nitride powder, 41 wt% a mixed solvent of ethanol and xylene in a mass ratio of 1:1, 7 wt% polyvinyl butyral, and 2 wt% PEG 200; and the dispersant comprises 0.5 wt% Shanggao Sago8080 and 1.5 wt% Shanggao Sago9780.

[0103] The preparation method of the aluminum nitride casting slurry based on a bi-dispersant includes the following steps: 1) Solvent system preparation: Add PVB (polyvinyl butyral) and PEG 200 (polyethylene glycol 200) to the solvent, stir at 200 rpm for 30 min.

[0104] 2) Pretreatment of main material powder: Add AlN powder (D50=1-1.5μm) to the solvent system in step 1), with a ball-to-powder ratio of 2:1, and ball mill at 200rpm for 1.5h.

[0105] 3) Low polarity dispersant: Dissolve Sago8080 in a small amount of solvent, then slowly add it dropwise to the slurry obtained in step 2), and ball mill at 400 rpm for 2 h.

[0106] 4) High polarity dispersant: Add Sago9780 to step 3 and ball mill at 300 rpm for 4 h.

[0107] 5) Degassing and casting: Degas the slurry mixed in step 4) under vacuum for 30 min, cast to a thickness of 500 μm at a casting speed of 0.1 m / min, and then perform gradient drying at 35℃-55℃ for 75 min.

[0108] 6) Sintering: Sinter at 1850℃ for 3 hours in a nitrogen atmosphere.

[0109] Example 12 A dual-dispersant-based aluminum nitride casting slurry, comprising a pre-mixed material and a dispersant, wherein the pre-mixed material comprises the following components: 50 wt% aluminum nitride powder, 41 wt% a mixed solvent of ethanol and xylene in a mass ratio of 3:2, 7 wt% polyvinyl butyral, and 2 wt% PEG 200; and the dispersant comprises 0.5 wt% Shanggao Sago8080 and 1.5 wt% Shanggao Sago9780.

[0110] The preparation method of the aluminum nitride casting slurry based on a bi-dispersant includes the following steps: 1) Solvent system preparation: Add PVB (polyvinyl butyral) and PEG 200 (polyethylene glycol 200) to the solvent, stir at 200 rpm for 30 min.

[0111] 2) Pretreatment of main material powder: Add AlN powder (D50=1-1.5μm) to the solvent system in step 1), with a ball-to-powder ratio of 2:1, and ball mill at 200rpm for 1.5h.

[0112] 3) Low polarity dispersant: Dissolve Sago8080 in a small amount of solvent, then slowly add it dropwise to the slurry obtained in step 2), and ball mill at 400 rpm for 2 h.

[0113] 4) High polarity dispersant: Add Sago9780 to step 3 and ball mill at 300 rpm for 4 h.

[0114] 5) Degassing and casting: Degas the slurry mixed in step 4) under vacuum for 30 min, cast to a thickness of 500 μm at a casting speed of 0.1 m / min, and then perform gradient drying at 35℃-55℃ for 75 min.

[0115] 6) Sintering: Sinter at 1850℃ for 3 hours in a nitrogen atmosphere.

[0116] Example 13 A bi-dispersant-based aluminum nitride casting slurry, comprising a pre-mixed material and a dispersant, wherein the pre-mixed material comprises the following components: 50 wt% aluminum nitride powder, 41 wt% a mixed solvent of ethanol and toluene in a mass ratio of 7:3, 7 wt% polyvinyl butyral, and 2 wt% PEG 200; and the dispersant comprises 0.5 wt% Shanggao Sago8080 and 2.5 wt% Shanggao Sago9780.

[0117] The preparation method of the aluminum nitride casting slurry based on a bi-dispersant includes the following steps: 1) Solvent system preparation: Add PVB (polyvinyl butyral) and PEG 200 (polyethylene glycol 200) to the solvent, stir at 200 rpm for 30 min.

[0118] 2) Pretreatment of main material powder: Add AlN powder (D50=1-1.5μm) to the solvent system in step 1), with a ball-to-powder ratio of 2:1, and ball mill at 200rpm for 1.5h.

[0119] 3) Low polarity dispersant: Dissolve Sago8080 in a small amount of solvent, then slowly add it dropwise to the slurry obtained in step 2), and ball mill at 400 rpm for 2 h.

[0120] 4) High polarity dispersant: Add Sago9780 to step 3 and ball mill at 300 rpm for 4 h.

[0121] 5) Degassing and casting: Degas the slurry mixed in step 4) under vacuum for 30 min, cast to a thickness of 500 μm at a casting speed of 0.1 m / min, and then perform gradient drying at 35℃-55℃ for 75 min.

[0122] 6) Sintering: Sinter at 1850℃ for 3 hours in a nitrogen atmosphere.

[0123] Example 14 A bi-dispersant-based aluminum nitride casting slurry, comprising a pre-mixed material and a dispersant, wherein the pre-mixed material comprises the following components: 50 wt% aluminum nitride powder, 41 wt% a mixed solvent of ethanol and toluene in a mass ratio of 7:3, 7 wt% polyvinyl butyral, and 2 wt% PEG 200; and the dispersant comprises 0.7 wt% Shanggao Sago8080 and 1.5 wt% Shanggao Sago9780.

[0124] The preparation method of the aluminum nitride casting slurry based on a bi-dispersant includes the following steps: 1) Solvent system preparation: Add PVB (polyvinyl butyral) and PEG 200 (polyethylene glycol 200) to the solvent, stir at 200 rpm for 30 min.

[0125] 2) Pretreatment of main material powder: Add AlN powder (D50=1-1.5μm) to the solvent system in step 1), with a ball-to-powder ratio of 2:1, and ball mill at 200rpm for 1.5h.

[0126] 3) Low polarity dispersant: Dissolve Sago8080 in a small amount of solvent, then slowly add it dropwise to the slurry obtained in step 2), and ball mill at 400 rpm for 2 h.

[0127] 4) High polarity dispersant: Add Sago9780 to step 3 and ball mill at 300 rpm for 4 h.

[0128] 5) Degassing and casting: Degas the slurry mixed in step 4) under vacuum for 30 min, cast to a thickness of 500 μm at a casting speed of 0.1 m / min, and then perform gradient drying at 35℃-55℃ for 75 min.

[0129] 6) Sintering: Sinter at 1850℃ for 3 hours in a nitrogen atmosphere.

[0130] Example 15 A bi-dispersant-based aluminum nitride casting slurry, comprising a pre-mixed material and a dispersant, wherein the pre-mixed material comprises the following components: 50 wt% aluminum nitride powder, 41 wt% a mixed solvent of ethanol and toluene in a mass ratio of 3:2, 7 wt% polyvinyl butyral, and 2 wt% PEG 200; and the dispersant comprises 1 wt% Shanggao Sago8080 and 1 wt% Shanggao Sago9780.

[0131] The preparation method of the aluminum nitride casting slurry based on a bi-dispersant includes the following steps: 1) Solvent system preparation: Add PVB (polyvinyl butyral) and PEG 200 (polyethylene glycol 200) to the solvent, stir at 200 rpm for 30 min.

[0132] 2) Pretreatment of main material powder: Add AlN powder (D50=1-1.5μm) to the solvent system in step 1), with a ball-to-powder ratio of 2:1, and ball mill at 200rpm for 1.5h.

[0133] 3) Low polarity dispersant: Dissolve Sago8080 in a small amount of solvent, then slowly add it dropwise to the slurry obtained in step 2), and ball mill at 400 rpm for 2 h.

[0134] 4) High polarity dispersant: Add Sago9780 to step 3 and ball mill at 300 rpm for 4 h.

[0135] 5) Degassing and casting: Degas the slurry mixed in step 4) under vacuum for 30 min, cast to a thickness of 500 μm at a casting speed of 0.1 m / min, and then perform gradient drying at 35℃-55℃ for 75 min.

[0136] 6) Sintering: Sinter at 1850℃ for 3 hours in a nitrogen atmosphere.

[0137] Example 16 A dual-dispersant-based aluminum nitride casting slurry, comprising a pre-mixed material and a dispersant, wherein the pre-mixed material comprises the following components: 50 wt% aluminum nitride powder, 41 wt% a mixed solvent of ethanol and toluene in a mass ratio of 7:3, 7 wt% polyvinyl butyral, and 2 wt% PEG 200; and the dispersant comprises 0.5 wt% Shanggao Sago8080 and 2 wt% Shanggao Sago9780.

[0138] The preparation method of the aluminum nitride casting slurry based on a bi-dispersant includes the following steps: 1) Solvent system preparation: Add PVB (polyvinyl butyral) and PEG 200 (polyethylene glycol 200) to the solvent, stir at 200 rpm for 30 min.

[0139] 2) Pretreatment of main material powder: Add AlN powder (D50=1-1.5μm) to the solvent system in step 1), with a ball-to-powder ratio of 2:1, and ball mill at 200rpm for 1.5h.

[0140] 3) Low polarity dispersant: Dissolve Sago8080 in a small amount of solvent, then slowly add it dropwise to the slurry obtained in step 2), and ball mill at 400 rpm for 2 h.

[0141] 4) High polarity dispersant: Add Sago9780 to step 3 and ball mill at 300 rpm for 4 h.

[0142] 5) Degassing and casting: Degas the slurry mixed in step 4) under vacuum for 30 min, cast to a thickness of 500 μm at a casting speed of 0.1 m / min, and then perform gradient drying at 35℃-55℃ for 75 min.

[0143] 6) Sintering: Sinter at 1850℃ for 3 hours in a nitrogen atmosphere.

[0144] Example 17 A bi-dispersant-based aluminum nitride casting slurry, comprising a pre-mixed material and a dispersant, wherein the pre-mixed material comprises the following components: 50 wt% aluminum nitride powder, 41 wt% a mixed solvent of ethanol and xylene in a mass ratio of 7:3, 7 wt% polyvinyl butyral, and 2 wt% PEG 200; and the dispersant comprises 0.5 wt% Shanggao Sago8080 and 2 wt% Shanggao Sago9780 in the pre-mixed material.

[0145] The preparation method of the aluminum nitride casting slurry based on a bi-dispersant includes the following steps: 1) Solvent system preparation: Add PVB (polyvinyl butyral) and PEG 200 (polyethylene glycol 200) to the solvent, stir at 200 rpm for 30 min.

[0146] 2) Pretreatment of main material powder: Add AlN powder (D50=1-1.5μm) to the solvent system in step 1), with a ball-to-powder ratio of 2:1, and ball mill at 200rpm for 1.5h.

[0147] 3) Low polarity dispersant: Dissolve Sago8080 in a small amount of solvent, then slowly add it dropwise to the slurry obtained in step 2), and ball mill at 400 rpm for 2 h.

[0148] 4) High polarity dispersant: Add Sago9780 to step 3 and ball mill at 300 rpm for 4 h.

[0149] 5) Degassing and casting: Degas the slurry mixed in step 4) under vacuum for 30 min, cast to a thickness of 500 μm at a casting speed of 0.1 m / min, and then perform gradient drying at 35℃-55℃ for 75 min.

[0150] 6) Sintering: Sinter at 1850℃ for 3 hours in a nitrogen atmosphere.

[0151] Comparative Example 1 The difference between this comparative example and Example 1 is that only 2.5 wt% oleic acid (a low-polarity dispersant) is used as the dispersant.

[0152] Comparative Example 2 The difference between this comparative example and Example 2 is that only 2.5 wt% PEI (highly polar dispersant) is used as the dispersant.

[0153] Comparative Example 3 The difference between this comparative example and Example 3 is that only 2.5 wt% of Sago8080 (a low-polarity dispersant) was used as the dispersant.

[0154] Comparative Example 4 The difference between this comparative example and Example 4 is that only 2.5 wt% of Sago9780 (a highly polar dispersant) was used as the dispersant.

[0155] Comparative Example 5 The difference between this comparative example and Example 10 is that only 2.5 wt% oleic acid (a low-polarity dispersant) is used as the dispersant.

[0156] Comparative Example 6 The difference between this comparative example and Example 10 is that only 2.5 wt% PEI (highly polar dispersant) is used as the dispersant.

[0157] Comparative Example 7 The difference between this comparative example and Example 10 is that only 2.5 wt% of Sago8080 (a low-polarity dispersant) is used as the dispersant.

[0158] Comparative Example 8 The difference between this comparative example and Example 12 is that only 2.5 wt% of Sago9780 (a highly polar dispersant) was used as the dispersant.

[0159] Comparison table of viscosity & thermal conductivity results between Examples 1-17 and Comparative Examples 1-8

[0160] Figure 2 The image shows a SEM image of the green body prepared using the bidispersants Sago8080 and Sago9780 in Example 16, combined with... Figure 2As can be seen from the data in Table 1, the combination of Sago8080 and Sago9780 dispersants results in the best colloidal dispersion efficiency and system stability (colloids are present in the shaded area).

[0161] Figure 3 SEM image of the green body prepared using a single dispersant, the highly polar Sago9780, for Comparative Example 4; Combination Figure 3 The data in Table 1 show that the use of a high-polarity dispersant indirectly reflects the agglomeration of colloids. The high-polarity dispersant cannot effectively address all the structures on the powder surface, resulting in poor system stability (colloids are present in the shaded areas).

[0162] Figure 4 SEM image of the green body prepared using a single low-polarity dispersant, Sago8080, in Comparative Example 3. Combination Figure 4 As can be seen from the data in Table 1, relying solely on low-polarity dispersants, whose molecular chains are short, is insufficient to resist the adsorption and aggregation between powder particles in the system. This results in the colloids and powders encapsulating each other, making it difficult to disperse uniformly in the solvent (colloids exist in the shaded areas).

[0163] Figure 5 SEM images of sintered bodies prepared using different solvent ratios with the same proportions of bidispersant (Sago8080-0.5wt% and Sago9780-1.5wt%) in Examples 3, 6, and 9 are shown, where (a) is Example 3, (b) is Example 6, and (c) is Example 9. Figure 5 As can be seen from the data in Table 1, when comparing different addition ratios of the same solvent, the SEM morphology of the sintered body shows that the addition ratio of solvent affects the wetting distribution of the powder. A lower solvent ratio results in poor uniformity of the colloid and powder, leading to some overburning behavior after sintering.

[0164] Figure 6 The images show SEM images of sintered bodies prepared using different proportions of bidispersants (Sago8080 and Sago9780) in solvents of equal ratio (ethanol + toluene = 7:3) in Examples 13, 14, 15, and 16, where (a) is Example 13, (b) is Example 14, (c) is Example 15, and (d) is Example 16. Figure 6 As can be seen from the data in Table 1, compared with different proportions of bidispersants with the same solvent ratio, the low-polarity bidispersant contains a carboxyl group (-COOH), which can react with the Al in the highly active Al-O bonds on the surface of aluminum nitride. 3+The formation of coordination compounds also provides a certain anchoring basis for the highly polar molecules of the block copolymer. Aluminum nitride ceramic casting slurry exists in an organic system where the electrostatic forces between particles are weak, making it difficult to maintain the stability of the entire system. Simultaneously, the Al-N bonds on the surface of aluminum nitride easily form hydrogen bonds, leading to inter-particle bonding and difficulty in dispersing the powder particles. Considering these factors, a block polymer molecule with high polarity as a dispersant is used. This dispersant forms a strong interaction with the Al-N bonds on the surface of the aluminum nitride powder in the form of anchoring groups. The anchoring groups of the dispersant adsorb onto the powder surface, and the solvated chains extend into the solvent to form a protective layer, preventing particle aggregation. At the same time, the high polarity chains also provide a strong steric hindrance effect, which is beneficial to the stability of the entire slurry system and is a key step in the preparation of high thermal conductivity aluminum nitride ceramic substrates. SEM morphology of the sintered body shows that increasing the amount of low-polarity additives makes electrostatic forces play a dominant role in the system, leading to powder agglomeration. This is reflected in the abnormal growth of some grains during sintering. Increasing the amount of high-polarity additives makes steric hindrance play a dominant role in the system. The steric hindrance is insufficient to resist the forces of Al-O and hydroxyl (-OH) groups in the entire system. During solvent evaporation, the colloids cause the powder to flocculate and agglomerate, resulting in changes in the density uniformity of the green body. This is reflected in the significant differences in grain size and the presence of some pores in the sintered body. The resulting defects directly lead to a decrease in thermal conductivity.

[0165] Figure 7 SEM images of sintered bodies prepared using different solvent systems with the same proportion of a single dispersant in Comparative Examples 3, 4, 7, and 8 are shown, where (a) is Comparative Example 3, (b) is Comparative Example 4, (c) is Comparative Example 7, and (d) is Comparative Example 8. Figure 7 As shown in Table 1, comparing different addition ratios of the same solvent, the SEM morphology of the sintered bodies reveals that in a single dispersant system, low-polarity dispersants mainly form coordination bonds with the powder surface structure. Their short molecular chains make it difficult to overcome the weak electrostatic forces of the powder molecules. The hydroxyl groups (-OH) on the powder surface easily form hydrogen bonds, leading to agglomeration and flocculation of the powder and colloid. This results in poor powder dispersion throughout the green body, causing partial over-burning and grain melting after sintering, forming a glassy phase and affecting the overall thermal conductivity. High-polarity dispersants, with their longer molecular chains, can provide effective steric hindrance, but due to their large structure, they cannot easily adhere to the Al-O bonds on the powder surface, easily forming Al-O-Al bonds. This makes the particles agglomerate in the colloid and difficult to disperse. In other words, under the same sintering conditions, the sintering driving force is greater, resulting in more pores and poorer compactness in the sintered body, thus leading to lower thermal conductivity.

[0166] Combining the data in the table and Figures 2-6It can be seen that the use of high-polarity and low-polarity dispersants in this invention is more conducive to controlling the viscosity of the slurry to around 2 Pa·s. The slurry viscosity is moderate, the colloidal dispersibility is good, and the fluidity of the slurry and the uniform distribution of powder in the colloid under natural conditions are guaranteed. This prevents the precipitation of colloids during the casting and drying process, ensuring the compactness of the grains after sintering, which is more conducive to improving the thermal conductivity. Conversely, from the single dispersant system, it can be seen that low-polarity dispersants mainly form coordination bonds with the powder surface structure. The molecular chain is relatively short and it is difficult to overcome the weak electrostatic force of the powder molecules. The hydroxyl groups (-OH) on the powder surface are prone to forming hydrogen bonds, which makes the powder easy to undergo electrostatic adsorption in the entire green body, resulting in uneven powder dispersion. After sintering, some over-burning and grain melting occur, forming a glassy phase, which affects the overall thermal conductivity.

[0167] Highly polar dispersants have long molecular chains that can act as steric hindrances, but their large high-polarity structures make it difficult to break the Al-O bonds on the powder surface. Electrostatic forces cause the powder to not be evenly distributed in the colloid. During sintering, due to the uneven distribution of the powder in the system, the required sintering driving force is relatively large. That is, under the same sintering conditions, the sintered body has more pores, poorer compactness, and thus lower thermal conductivity.

[0168] In summary, this invention employs a dual dispersant system. When two types of dispersants are used synergistically, the different molecular weights of the dispersants bond or coordinate with the different structures on the aluminum nitride surface, thus solving the problem of difficult powder dispersion and achieving stability of the entire slurry system. By using dispersants with different anchoring groups targeting different active sites on the powder surface, more comprehensive and robust adsorption coverage can be achieved. This combination effectively solves the dispersion problem of powders with wide particle size distributions.

[0169] The above description is merely a preferred embodiment of the present invention, and should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. An aluminum nitride casting slurry based on a dual dispersant, characterized in that, The raw materials include spare materials and dispersants. The spare materials include 40wt%-55wt% aluminum nitride powder, 35wt%-45wt% solvent, 4wt%-8wt% binder, and 1wt%-2.5wt% plasticizer, totaling 100wt%. The dispersants include 0.5wt%-1wt% of low-polarity dispersant and 1.0wt%-2.5wt% of high-polarity dispersant in the spare materials.

2. The aluminum nitride casting slurry based on a dual dispersant according to claim 1, characterized in that, The low-polarity dispersant is oleic acid or SAGO 8080 additive.

3. The aluminum nitride casting slurry based on a dual dispersant according to claim 1, characterized in that, The highly polar dispersant is polyetherimide, BYK111 additive, or SAGO9780 additive.

4. The aluminum nitride casting slurry based on a dual dispersant according to claim 1, characterized in that, The solvent is at least two of ethanol, toluene, xylene, and acetone.

5. The aluminum nitride casting slurry based on a bi-dispersant according to claim 1, characterized in that, The adhesive is at least one of polyvinyl butyral, propylene resin, cellulose derivatives, and polystyrene, and the plasticizer is at least one of polyethylene glycol and phthalate.

6. The aluminum nitride casting slurry based on a dual dispersant according to claim 1, characterized in that, The aluminum nitride powder has an average particle size D50 of 1-1.5 μm.

7. A method for preparing an aluminum nitride casting slurry based on a bi-dispersant as described in any one of claims 1-6, characterized in that, Includes the following steps: (1) Mix the solvent, binder and plasticizer evenly; (2) Add aluminum nitride powder and wet grind it into a slurry; (3) Add the low-polarity dispersant to the slurry and continue ball milling; (4) Add a high polarity dispersant to the system and continue ball milling to obtain the aluminum nitride casting slurry based on the dual dispersant.

8. The method for preparing aluminum nitride casting slurry based on a bi-dispersant according to claim 7, characterized in that, In step (2), a ball mill is used for wet milling. The mass ratio of balls to powder is 1-2:1, the ball milling speed is 200-300 rpm, and the wet milling time is 1-2 hours.

9. The method for preparing aluminum nitride casting slurry based on a bi-dispersant according to claim 7, characterized in that, In step (3), the specific process is as follows: dissolve the low polarity dispersant in a small amount of solvent, add it to the slurry, and ball mill at 400-500 rpm for 2-4 hours; In step (4), the ball milling speed is 300-400 rpm and the ball milling time is 2-4 hours.

10. The method for preparing aluminum nitride casting slurry based on a bi-dispersant according to claim 7, characterized in that, It also includes a molding step: after degassing the slurry obtained in step (4), it is cast and dried to obtain a green ceramic tape with a thickness of about 100–150 μm, which is used for subsequent sintering and molding; the casting parameters are: the scraper height is set to 300–500 μm, the casting speed is 0.1 m / min, and after casting, it is dried at 35–55℃ for 60–80 min to obtain a green ceramic tape with a thickness of about 100–150 μm, which is used for subsequent sintering and molding.

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