Preparation method of industrial grade aluminum nitride ceramic substrate with high thermal conductivity

Abstract

The invention relates to the technical field of ceramic preparation, provides a preparation method of a high-heat-conductivity industrial-grade aluminum nitride ceramic substrate, and solves the problems that an aluminum nitride ceramic substrate prepared by the existing technical scheme cannot have high industrial production efficiency, low cost and high heat conduction efficiency at the same time. Comprising the following steps: (1) synthesizing alpha-Al2O3 by adopting an ultrasonic spray pyrolysis method; (2) uniformly mixing alpha-Al2O3 and carbon black, carrying out high-temperature synthesis and decarburization treatment, adding a sintering aid, and uniformly mixing to obtain a third mixture; (3) uniformly mixing methylbenzene and absolute ethyl alcohol, and adding polyvinyl butyral, dioctyl phthalate, a dispersing agent, an adhesive and absolute ethyl alcohol to obtain second slurry; (4) adding the third mixture into the second slurry, and uniformly mixing; (5) pouring into a mold to obtain an AlN sheet; (6) the AlN sheets are stacked and then subjected to pressing treatment; and (7) sintering and cooling to room temperature to obtain the aluminum nitride ceramic substrate.

Description

Technical Field

[0001] The invention relates to the technical field of ceramic preparation, and in particular to a method for preparing an industrial-grade aluminum nitride ceramic substrate with high thermal conductivity. Background Art

[0002] Aluminum nitride (AlN) ceramics have a theoretical thermal conductivity of up to 320 W / (m·K) and a thermal expansion coefficient that matches that of silicon (4.5×10 -8 / ℃), low dielectric constant (8~10), excellent insulation performance and environmental protection and non-toxicity make it an ideal choice for the new generation of high thermal conductivity electronic substrates and packaging materials.

[0003] Chinese patent application number CN201611054095.0 discloses an aluminum nitride powder for an aluminum nitride ceramic substrate and a preparation method thereof, wherein the preparation method of the aluminum nitride powder comprises the following steps: (a), preparing a precursor mixture; (b), high temperature synthesis; (c), decarburization treatment; (d), surface treatment. The preparation method provided by the invention is simple, has a low synthesis temperature, is pollution-free, and is suitable for large-scale production. The invention also provides an aluminum nitride powder prepared by the above method, wherein the prepared aluminum nitride powder has good water resistance and the trace elements required for the sintering process of the aluminum nitride substrate are evenly distributed in the powder, and a more suitable powder particle size range is obtained by adjusting the amount of sintering aid used, thereby improving the density, thermal conductivity and shock resistance of the substrate. However, the alumina powder used in the technical solution has more impurities and a higher purchase cost than the method of atomization pyrolysis synthesis of aluminum salt solution used in the present application.

[0004] Chinese patent application number CN202411116576.4 discloses an aluminum nitride ceramic substrate and a preparation method thereof, wherein the raw materials include aluminum nitride powder and a sintering aid; the sintering aid includes a calcium compound and component A; the mass ratio of component A to the calcium compound is 1 to 4:1; the component A includes an ytterbium compound, a lanthanum compound, and a europium compound, and the mass ratio of the ytterbium compound, the lanthanum compound, and the europium compound is 1:1:1 to 3; the aluminum nitride powder is polycaprolactone-modified aluminum nitride powder; the preparation method of the polycaprolactone-modified aluminum nitride powder includes the following steps: dissolving polycaprolactone and mixing it with aluminum nitride powder, drying it, and obtaining polycaprolactone-modified aluminum nitride powder; the mass ratio of polycaprolactone to aluminum nitride powder is 0.1 to 0.4:2. Through the above technical solution, the problem of low bending strength and thermal conductivity of aluminum nitride ceramic substrates in the related art is solved. However, this technical solution uses more expensive rare earth oxides, and the cost of industrial production is high. Summary of the invention

[0005] Therefore, in view of the above problems, the present invention provides a method for preparing an industrial-grade aluminum nitride ceramic substrate with high thermal conductivity, which solves the problem that the aluminum nitride ceramic substrate prepared by the prior art solution cannot have both high industrial production efficiency, low cost and high thermal conductivity.

[0006] To achieve the above object, the present invention adopts the following technical solutions: A method for preparing an industrial-grade aluminum nitride ceramic substrate with high thermal conductivity comprises the following steps: S1. Preparation of raw materials: α-Al 2 O 3 , carbon black, sintering aids; S2, according to the α-Al 2 O 3 The molar ratio of α-Al to carbon black is 4-6:1. 2 O 3 and carbon black to obtain a first mixture, and placing the first mixture in a tube furnace at N 2 Under protection, raising the temperature to 1600°C-1650°C and keeping it for 2h-3h. After the reaction is completed, lowering the temperature to 700°C-750°C and then cooling naturally to room temperature to obtain a second mixture; S3, mixing the second mixture and the sintering aid uniformly in a ratio of 96wt%-99wt% of the second mixture and the remainder being the sintering aid to obtain a third mixture; S4, according to the weight ratio of toluene to anhydrous ethanol of 1:1-1.5, toluene and anhydrous ethanol are mixed uniformly to obtain a first slurry; take 50wt%-55wt% of the first slurry by mass, add 1wt%-2wt% of polyvinyl butyral, 1wt%-2wt% of dioctyl phthalate, 1wt%-2wt% of dispersant, 1wt%-2wt% of adhesive, and the balance is anhydrous ethanol to the first slurry, mix uniformly, and obtain a second slurry; S5, adding the third mixture to the second slurry, mixing evenly to obtain a third slurry, adding Al 2 O 3 The pellets are ball-milled; the third slurry after ball milling is placed in a drying furnace for evaporation and degassing, and then the third slurry is poured into a mold at a pouring speed of 25 cm / min, and dried at 70° C.-75° C. for 10 h-12 h to obtain a plurality of AlN sheets with a thickness of 160 μm-180 μm; S6, stacking 2-4 AlN sheets, and then pressing them to obtain a rough AlN substrate with a thickness of 1.0 mm-1.5 mm; S7, thermally degreasing the rough AlN substrate, and then heating it in a BN crucible under N 2 sintering under a temperature-controlled atmosphere and cooling to room temperature to obtain the aluminum nitride ceramic substrate; Wherein, the α-Al 2 O 3 The synthesis process is as follows: the aluminum salt solution is converted into aluminum salt fine mist, which is transported to a quartz reaction tube, and the temperature is raised to 1200℃-1400℃. A thermal decomposition reaction occurs in the quartz reaction tube. After the thermal decomposition reaction is completed, α-Al 2 O 3 .

[0007] Furthermore, the aluminum salt is Al(NO 3 ) 3 6H 2 O or AlCl 3 6H 2 O.

[0008] Furthermore, the α-Al 2 O 3 The synthesis is carried out in a synthesis system comprising an air mover, an ultrasonic atomizer, a tubular furnace equipped with a quartz reaction tube, a product collector and an acid absorber.

[0009] Furthermore, the concentration of the aluminum salt solution is 0.001 mol / L-0.002 mol / L.

[0010] Furthermore, the delivery rate of the aluminum salt mist to the quartz reaction tube is 5L / min-7L / min.

[0011] Furthermore, the α-Al 2 O 3 The purity is ≥99.9% and the particle size is ≤100nm.

[0012] Furthermore, the carbon black is MA100, and the particle size is ≤20nm.

[0013] Furthermore, the sintering aid is Y 2 O 3 , purity ≥99.99%.

[0014] Furthermore, in step S2, the temperature increasing rate is 10°C / min.

[0015] Furthermore, in step S2, the temperature reduction rate is 5°C / min.

[0016] By adopting the above technical solution, the beneficial effects of the present invention are: Using Al(NO3 ) 3 6H 2 O or AlCl 3 6H 2 O aluminum salt solution is used as a precursor solution, and after ultrasonic atomization, it is decomposed at high temperature to form α-Al 2 O 3 , avoiding the introduction of impurities, and obtaining high-purity α-Al 2 O 3 The high-temperature pyrolysis process effectively removes organic matter or solvent residues and reduces impurity pollution. The preparation process is simple and low-cost, making it suitable for industrial production.

[0017] Ultrasonic atomization disperses the solution into micron-sized droplets, ensuring uniform distribution of the precursor, and generates nano- or submicron-sized α-Al after pyrolysis. 2 O 3 Particles, the cavitation effect of ultrasound disperses the particles, combined with high temperature calcination, reduce hard agglomeration, and obtain a spherical or quasi-spherical structure with good dispersion.

[0018] The atomized droplets are rapidly dehydrated and crystallized in a tubular furnace equipped with a quartz reaction tube, promoting the amorphous Al 2 O 3 Transform to α phase (high temperature stable phase), avoid intermediate phase (such as γ-Al 2 O 3 ) remains. And the phase change efficiency is high, short-time high temperature treatment accelerates the crystal transformation, and the product is a single α-Al 2 O 3 It is mainly composed of quartz and has high crystallinity, which is conducive to industrial production. Combined with an acid absorber, it can prevent air pollution.

[0019] Carbon black MA100 is used as a carbon source. Its particle size is ≤20nm, with high porosity and high specific surface area, making it easier to adhere to α-Al 2 O 3 The particle surface and α-Al 2 O 3 Good blending; carbon black acts as a nano-scale dispersant to inhibit the formation of AlN and α-Al 2 O 3 The agglomeration of particles makes the microstructure of the sintered body more uniform, reduces the porosity, and increases the relative density of aluminum nitride ceramics. High density can reduce grain boundary defects and significantly improve bending strength and fracture toughness. At the same time, carbon black is inexpensive and can replace some expensive rare earth oxides (Y 2 O 3 The amount used is reduced), which can significantly reduce production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic diagram of the structure of a synthesis system in an embodiment of the present invention; Explanation of the numbers in the figure: 1-air mover, 2-ultrasonic atomizer, 3-tube furnace equipped with quartz reaction tube, 4-product collector, 5-acid absorber. DETAILED DESCRIPTION

[0021] Example 1

[0022] A method for preparing an industrial-grade aluminum nitride ceramic substrate with high thermal conductivity, characterized in that it comprises the following steps: (1) Preparation of raw materials: Raw materials include: α-Al 2 O 3 , carbon black, sintering aid; the α-Al 2 O 3 The purity is 99.9% and the particle size is 100nm; the carbon black is MA100 and the particle size is 20nm; the sintering aid is Y 2 O 3 , purity is 99.99%; (1-1) α-Al 2 O 3 Synthesis system: The α-Al 2 O 3 Synthesized by ultrasonic spray pyrolysis, Figure 1 , the α-Al 2 O 3 The synthesis is carried out in a synthesis system, which comprises: an air mover 1, an ultrasonic atomizer 2, a tubular furnace 3 equipped with a quartz reaction tube, a product collector 4 and an acid absorber 5; (1-2) α-Al 2 O 3 The synthesis process: Al(NO 3 ) 3 6H 2 The O solution is converted into aluminum salt mist and transported to the quartz reaction tube. The temperature is raised to 1200℃, and a thermal decomposition reaction occurs in the quartz reaction tube. After the thermal decomposition reaction is completed, α-Al 2 O 3 ; The Al(NO 3 ) 3 6H 2 The concentration of O solution is 0.001 mol / L; the delivery rate is 5 L / min; The synthesis reaction equation is as follows:

[0023] (2) According to the α-Al 2 O 3The molar ratio of α-Al to carbon black is 4:1. 2 O 3 and carbon black to obtain a first mixture, and placing the first mixture in a tube furnace at N 2 Under protection, the temperature was raised to 1600° C. at a heating rate of 10° C. / min, and kept warm for 2 hours. After the reaction was completed, the temperature was lowered to 750° C. at a cooling rate of 5° C. / min, and then naturally cooled to room temperature to obtain a second mixture; (3) mixing the second mixture and the sintering aid in a ratio of 96 wt % of the second mixture and the remainder of the sintering aid to obtain a third mixture; (4) mixing toluene and anhydrous ethanol in a weight ratio of 1:1 to obtain a first slurry; taking 50 wt % of the first slurry, adding 1 wt % of polyvinyl butyral, 1 wt % of dioctyl phthalate, 1 wt % of a dispersant, 1 wt % of a binder, and the balance being anhydrous ethanol, to the first slurry, and mixing them uniformly to obtain a second slurry; (5) Add the third mixture to the second slurry, mix well to obtain a third slurry, and add Al 2 O 3 The pellets are ball-milled; the third slurry after ball milling is placed in a drying furnace for evaporation and degassing, and then the third slurry is poured into a mold at a pouring speed of 25 cm / min, and dried at 70° C. for 10 hours to obtain a number of AlN sheets with a thickness of 160 μm; (6) stacking the AlN sheets described in step 2, and then pressing them to obtain a rough AlN substrate with a thickness of 1.0 mm to 1.5 mm; (7) The rough AlN substrate is subjected to thermal degreasing treatment and then heated in a BN crucible under N 2 The aluminum nitride ceramic substrate is sintered under a vacuum atmosphere and cooled to room temperature to obtain the aluminum nitride ceramic substrate.

[0024] Example 2

[0025] A method for preparing an industrial-grade aluminum nitride ceramic substrate with high thermal conductivity, characterized in that it comprises the following steps: (1) Preparation of raw materials: Raw materials include: α-Al 2 O 3 , carbon black, sintering aid; the α-Al 2 O 3 The purity is 99.9% and the particle size is 80nm; the carbon black is MA100 and the particle size is 20nm; the sintering aid is Y 2O 3 , purity is 99.99%; (1-1) α-Al 2 O 3 Synthesis system: The α-Al 2 O 3 Synthesized by ultrasonic spray pyrolysis, Figure 1 , the α-Al 2 O 3 The synthesis is carried out in a synthesis system, which comprises: an air mover 1, an ultrasonic atomizer 2, a tubular furnace 3 equipped with a quartz reaction tube, a product collector 4 and an acid absorber 5; (1-2) α-Al 2 O 3 The synthesis process: AlCl 3 6H 2 The O solution is converted into aluminum salt mist and transported to the quartz reaction tube. The temperature is raised to 1300℃, and a thermal decomposition reaction occurs in the quartz reaction tube. After the thermal decomposition reaction is completed, α-Al 2 O 3 ; The AlCl 3 6H 2 The concentration of O solution is 0.001 mol / L; the delivery rate is 5 L / min; The synthesis reaction equation is as follows:

[0026] (2) According to the α-Al 2 O 3 The molar ratio of α-Al to carbon black is 4:1. 2 O 3 and carbon black to obtain a first mixture, and placing the first mixture in a tube furnace at N 2 Under protection, the temperature was raised to 1600° C. at a heating rate of 10° C. / min, and kept warm for 2 hours. After the reaction was completed, the temperature was lowered to 750° C. at a cooling rate of 5° C. / min, and then naturally cooled to room temperature to obtain a second mixture; (3) mixing the second mixture and the sintering aid in a ratio of 97 wt % of the second mixture and the remainder of the sintering aid to obtain a third mixture; (4) mixing toluene and anhydrous ethanol in a weight ratio of 1.2:1 to obtain a first slurry; taking 52 wt% of the first slurry, adding 1 wt% of polyvinyl butyral, 1 wt% of dioctyl phthalate, 1 wt% of a dispersant, 1 wt% of a binder, and the balance being anhydrous ethanol to the first slurry, and mixing them uniformly to obtain a second slurry; (5) Add the third mixture to the second slurry, mix well to obtain a third slurry, and add Al 2 O 3 The pellets were ball-milled; the third slurry after ball milling was placed in a drying furnace for evaporation and degassing, and then the third slurry was poured into a mold at a pouring speed of 25 cm / min, and dried at 72° C. for 11 hours to obtain a number of AlN sheets with a thickness of 170 μm; (6) stacking three AlN sheets and pressing them to obtain a rough AlN substrate with a thickness of 1.2 mm; (7) The rough AlN substrate is subjected to thermal degreasing treatment and then heated in a BN crucible under N 2 The aluminum nitride ceramic substrate is sintered under a vacuum atmosphere and cooled to room temperature to obtain the aluminum nitride ceramic substrate.

[0027] Example 3

[0028] A method for preparing an industrial-grade aluminum nitride ceramic substrate with high thermal conductivity, characterized in that it comprises the following steps: (1) Preparation of raw materials: Raw materials include: α-Al 2 O 3 , carbon black, sintering aid; the α-Al 2 O 3 The purity is 99.9% and the particle size is 100nm; the carbon black is MA100 and the particle size is 20nm; the sintering aid is Y 2 O 3 , purity is 99.99%; (1-1) α-Al 2 O 3 Synthesis system: The α-Al 2 O 3 Synthesized by ultrasonic spray pyrolysis, Figure 1 , the α-Al 2 O 3 The synthesis is carried out in a synthesis system, which comprises: an air mover 1, an ultrasonic atomizer 2, a tubular furnace 3 equipped with a quartz reaction tube, a product collector 4 and an acid absorber 5; (1-2) α-Al2 O 3 The synthesis process: Al(NO 3 ) 3 6H 2 The O solution is converted into aluminum salt mist and transported to the quartz reaction tube. The temperature is raised to 1400℃, and a thermal decomposition reaction occurs in the quartz reaction tube. After the thermal decomposition reaction is completed, α-Al 2 O 3 ; The Al(NO 3 ) 3 6H 2 The concentration of O solution is 0.002 mol / L; the delivery rate is 7 L / min; The synthesis reaction equation is as follows:

[0029] (2) According to the α-Al 2 O 3 The molar ratio of α-Al to carbon black is 6:1. 2 O 3 and carbon black to obtain a first mixture, and placing the first mixture in a tube furnace at N 2 Under protection, the temperature was raised to 1650° C. at a heating rate of 10° C. / min, and the temperature was kept for 3 hours. After the reaction was completed, the temperature was lowered to 700° C. at a cooling rate of 5° C. / min, and then naturally cooled to room temperature to obtain a second mixture; (3) mixing the second mixture and the sintering aid in a ratio of 98 wt % of the second mixture and the remainder of the sintering aid to obtain a third mixture; (4) mixing toluene and anhydrous ethanol in a weight ratio of 1.5:1 to obtain a first slurry; taking 55 wt % of the first slurry, adding 2 wt % of polyvinyl butyral, 2 wt % of dioctyl phthalate, 2 wt % of a dispersant, 2 wt % of a binder, and the balance being anhydrous ethanol, to the first slurry, and mixing them uniformly to obtain a second slurry; (5) Add the third mixture to the second slurry, mix well to obtain a third slurry, and add Al 2 O 3 The pellets are ball-milled; the third slurry after ball milling is placed in a drying furnace for evaporation and degassing, and then the third slurry is poured into a mold at a pouring speed of 25 cm / min, and dried at 75° C. for 11 hours to obtain a number of AlN sheets with a thickness of 180 μm; (6) stacking four AlN sheets and pressing them to obtain a rough AlN substrate with a thickness of 1.2 mm; (7) The rough AlN substrate is subjected to thermal degreasing treatment and then heated in a BN crucible under N 2 The aluminum nitride ceramic substrate is sintered under a vacuum atmosphere and cooled to room temperature to obtain the aluminum nitride ceramic substrate.

[0030] Comparative Example 1 The difference from Example 1 is: Commercially available AlN powder, Y 2 O 3 The AlN powder has a purity of 99.99% and a particle size of 100 nm. 2 O 3 The purity is 99.99%; other technical solutions are the same as those in Example 1.

[0031] The test data of Example 1, Example 2, Example 3 and Comparative Example 1 are shown in Table 1.

[0032] Table 1

[0033] The thermal conductivity, bending strength and density of the products of Example 1, Example 2 and Example 3 all show good results, which indicates that the aluminum nitride ceramics prepared by the present invention have good quality.

[0034] Although the present invention has been specifically shown and described in conjunction with the preferred embodiments, it should be understood by those skilled in the art that various changes may be made to the present invention in form and details without departing from the spirit and scope of the present invention as defined by the appended claims, all of which are within the scope of protection of the present invention.

Claims

1. A method for preparing an industrial-grade aluminum nitride ceramic substrate with high thermal conductivity, characterized in that: The following steps are involved: S1. Preparation of raw materials: α-Al2O3, carbon black, sintering aid; S2, according to the molar ratio of α-Al2O3 to carbon black of 4-6:1, the α-Al2O3 and carbon black are mixed uniformly to obtain a first mixture, the first mixture is placed in a tube furnace, under N2 protection, the temperature is increased to 1600°C-1650°C, and the temperature is kept for 2h-3h. After the reaction is completed, the temperature is reduced to 700°C-750°C, and then naturally cooled to room temperature to obtain a second mixture; S3, mixing the second mixture and the sintering aid uniformly in a ratio of 96wt%-99wt% of the second mixture and the remainder being the sintering aid to obtain a third mixture; S4, according to the weight ratio of toluene to anhydrous ethanol of 1:1-1.5, toluene and anhydrous ethanol are mixed uniformly to obtain a first slurry; take 50wt%-55wt% of the first slurry by mass, add 1wt%-2wt% of polyvinyl butyral, 1wt%-2wt% of dioctyl phthalate, 1wt%-2wt% of dispersant, 1wt%-2wt% of adhesive, and the balance is anhydrous ethanol to the first slurry, mix uniformly, and obtain a second slurry; S5, adding the third mixture to the second slurry, mixing evenly to obtain a third slurry, adding Al2O3 pellets, and performing ball milling; placing the third slurry after ball milling into a drying furnace for evaporation and degassing, and then pouring the third slurry into a mold at a pouring speed of 25 cm / min, and drying at 70°C-75°C for 10h-12h to obtain a plurality of AlN flakes with a thickness of 160μm-180μm; S6, stacking 2-4 AlN sheets, and then pressing them to obtain a rough AlN substrate with a thickness of 1.0 mm-1.5 mm; S7, subjecting the rough AlN substrate to thermal degreasing treatment, and then sintering it in a BN crucible under a N2 atmosphere, and cooling it to room temperature to obtain the aluminum nitride ceramic substrate; The α-Al2O3 is synthesized by ultrasonic spray pyrolysis, and the synthesis process is as follows: converting the aluminum salt solution into aluminum salt fine mist, transporting it into a quartz reaction tube, raising the temperature to 1200°C-1400°C, allowing a thermal decomposition reaction to occur in the quartz reaction tube, and collecting the α-Al2O3 after the thermal decomposition reaction is completed.

2. The method for preparing a high thermal conductivity industrial grade aluminum nitride ceramic substrate according to claim 1, characterized in that: The aluminum salt is Al(NO3)3·6H2O or AlCl3·6H2O.

3. The method for preparing a high thermal conductivity industrial grade aluminum nitride ceramic substrate according to claim 1, characterized in that: The synthesis of α-Al2O3 is carried out in a synthesis system, which includes an air mover, an ultrasonic atomizer, a tubular furnace equipped with a quartz reaction tube, a product collector and an acid absorber.

4. The method for preparing a high thermal conductivity industrial grade aluminum nitride ceramic substrate according to claim 1, characterized in that: The concentration of the aluminum salt solution is 0.001 mol / L-0.002 mol / L.

5. The method for preparing a high thermal conductivity industrial grade aluminum nitride ceramic substrate according to claim 1, characterized in that: The aluminum salt fine mist is transported into the quartz reaction tube at a rate of 5 L / min-7 L / min.

6. The method for preparing a high thermal conductivity industrial grade aluminum nitride ceramic substrate according to claim 1, characterized in that: The purity of the α-Al2O3 is ≥99.9% and the particle size is ≤100nm.

7. The method for preparing a high thermal conductivity industrial grade aluminum nitride ceramic substrate according to claim 1, characterized in that: The carbon black is MA100, and the particle size is ≤20nm.

8. The method for preparing a high thermal conductivity industrial grade aluminum nitride ceramic substrate according to claim 1, characterized in that: The sintering aid is Y2O3, and the purity is ≥99.99%.

9. The method for preparing a high thermal conductivity industrial grade aluminum nitride ceramic substrate according to claim 1, characterized in that: In step S2, the temperature is increased at a rate of 10°C / min.

10. The method for preparing a high thermal conductivity industrial grade aluminum nitride ceramic substrate according to claim 1, characterized in that: In step S2, the temperature is lowered at a rate of 5°C / min.

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