Spherical aluminum nitride powder and method for producing the same

Abstract

This invention provides a spherical aluminum nitride powder and its preparation method, belonging to the field of inorganic powder processing. The spherical aluminum nitride powder is composed of primary aluminum nitride particles modified with dopamine and yttrium isopropoxide. The preparation method includes the following steps: mixing primary aluminum nitride particles with a dispersant, binder, dopamine, yttrium isopropoxide, and an organic solvent, followed by wet ball milling; spray granulation and debinding of the wet-milled slurry to obtain spherical granulated powder; debinding, sintering, crushing, and sieving of the spherical granulated powder to obtain spherical aluminum nitride powder. This invention uses dopamine and yttrium isopropoxide to improve the phase stability of primary aluminum nitride particles. Using the modified primary aluminum nitride particles as raw materials, the resulting spherical aluminum nitride powder exhibits a narrower particle size distribution, improved size uniformity, and controllable oxygen content.

Description

Technical Field

[0001] This invention belongs to the field of inorganic powder processing technology, and particularly relates to a spherical aluminum nitride powder and its preparation method. Background Technology

[0002] As core components of modern electronic devices, integrated circuits (ICs) containing various electronic components generate a significant amount of heat during operation, making thermal failure one of the main causes of electronic device failure. Therefore, the lightweight, miniaturized, and integrated design of ICs places high performance demands on the corresponding heat dissipation components. Aluminum nitride, with its excellent thermal conductivity, superior insulation properties, and low coefficient of thermal expansion, is widely used in high thermal conductivity ceramic substrates, insulating and thermally conductive fillers, and heat sinks. Among these, spherical aluminum nitride ceramic powders ranging from tens to hundreds of micrometers are of great significance for preparing fillers with high filler content and high thermal conductivity.

[0003] For example, Chinese invention patent application (title: "A method for preparing spherical large-particle aluminum nitride powder", publication number: CN104909762A, publication date: 20150916) discloses a method for preparing spherical large-particle aluminum nitride powder. The specific process is as follows: aluminum nitride powder, binder, sintering aid, and dispersant are mixed in an organic solvent to form a slurry. Spherical aluminum nitride agglomerates are obtained by spray granulation as granulation material, and then spherical aluminum nitride powder is obtained by high-temperature calcination and ball milling dispersion process.

[0004] However, during the wet ball milling process, the hydrolysis of some aluminum nitride raw materials leads to material deterioration and performance degradation, resulting in a wide particle size distribution of the final spherical aluminum nitride and uncontrollable oxygen content. Summary of the Invention

[0005] This invention addresses the shortcomings of existing methods for preparing spherical aluminum nitride powder by providing a spherical aluminum nitride powder and its preparation method. This invention utilizes dopamine and yttrium isopropoxide to improve the phase stability of primary aluminum nitride particles. Using the modified primary aluminum nitride particles as raw materials, the resulting spherical aluminum nitride powder exhibits a narrower particle size distribution, improved size uniformity, and controllable oxygen content.

[0006] The technical solution adopted in this invention is:

[0007] A spherical aluminum nitride powder is composed of primary aluminum nitride particles modified with dopamine and yttrium isopropoxide.

[0008] Furthermore, the aluminum nitride powder has D100 / D50 ≤ 2.8 and D90 / D10 ≤ 2.9.

[0009] Furthermore, the D50 of the aluminum nitride powder is 20–28 μm.

[0010] Furthermore, the proportion of aluminum nitride powder particles with a roundness of ≥0.8 is ≥70%.

[0011] Furthermore, the maximum particle size of aluminum nitride powder is ≤52μm.

[0012] Furthermore, the C-axis lattice constant of aluminum nitride powder is ≥4.978.

[0013] Based on the same inventive concept, the present invention also provides a method for preparing spherical aluminum nitride, comprising the following steps:

[0014] Step S1: The primary aluminum nitride particles are mixed with dispersant, binder, dopamine, yttrium isopropoxide and organic solvent, and then wet ball milled.

[0015] Step S2: Spray granulation is performed on the slurry obtained from wet ball milling in step S1 to obtain spherical granulated powder.

[0016] Step S3: The spherical granulated powder obtained by spray granulation and debinding in step S2 is debinded, sintered, crushed, and sieved to obtain spherical aluminum nitride powder.

[0017] Further, in step S1, the mass ratio of the dispersant to the primary aluminum nitride particles is 1:50 to 1:200;

[0018] The mass ratio of binder to primary aluminum nitride particles is 1:40 to 1:200;

[0019] The mass ratio of organic solvent to primary aluminum nitride particles is 0.9:1 to 1.3:1.

[0020] The dispersant is one or more of cationic surfactants, anionic surfactants, and nonionic surfactants; the binder is one or more of polyethylene glycol, polyvinylpyrrolidone, polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, tetrafluoroethylene, polyethylene, and polypropylene; and the organic solvent is one or more of ethanol, isopropanol, and acetone.

[0021] Furthermore, in step S1, the mass ratio of dopamine to primary aluminum nitride particles is 1:100 to 1:500;

[0022] The mass ratio of yttrium isopropoxide to primary aluminum nitride particles is 1:20 to 1:40.

[0023] Furthermore, in step S3, the temperature during glue removal is 500℃~700℃, the atmosphere is air, and the time is 2h~4h.

[0024] Furthermore, the sintering temperature is 1700℃~1950℃, the atmosphere is nitrogen, and the time is 2h~6h.

[0025] The beneficial effects of this invention are:

[0026] 1. This invention provides a method for preparing spherical aluminum nitride powder. Dopamine is introduced as a modifier during wet ball milling. The alkaline environment created during the hydrolysis of yttrium isopropoxide guides the modification and polymerization deposition of dopamine on the surface of primary aluminum nitride particles. The polymerization deposition of dopamine on the surface of primary aluminum nitride particles effectively prevents further contact with moisture, reduces particle deterioration, and achieves modification of the primary aluminum nitride particles. During spray granulation, the polymerization deposition of dopamine effectively ensures that the phase of aluminum nitride remains unchanged. Finally, spherical aluminum nitride products are prepared through processes such as debinding and sintering. Furthermore, as an organic compound, dopamine volatilizes during debinding and sintering, without introducing inorganic impurities into the final product. Moreover, the yttrium salts produced by the hydrolysis of yttrium isopropoxide can be uniformly dispersed in the spherical granulated powder, ultimately contributing to improved uniformity of aluminum nitride spheroid size.

[0027] 2. This invention provides a spherical aluminum nitride powder, composed of primary aluminum nitride particles modified with dopamine and yttrium isopropoxide. By using modified primary aluminum nitride particles as raw material, the resulting spherical aluminum nitride powder exhibits a narrowed particle size distribution, improved size uniformity, and controllable oxygen content. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a 68x full-field scanning electron microscope image of the spherical aluminum nitride in Example 1.

[0030] Figure 2 This is a magnified scanning electron microscope image of the largest particle in the spherical aluminum nitride product in Example 1. Detailed Implementation

[0031] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0032] The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Of course, these are merely examples and are not intended to limit the present invention.

[0033] The embodiments of the invention will now be described in detail with reference to the accompanying drawings.

[0034] Example 1

[0035] 100 parts by weight of micron-sized primary aluminum nitride particles (D50 = 1.6 μm), 90 parts by weight of ethanol, 5 parts by weight of yttrium isopropoxide, 1 part by weight of stearic acid, 2 parts by weight of polyvinylpyrrolidone, 1 part by weight of dopamine, and 150 parts by weight of ethanol were placed in a ball mill and wet-milled for 1 hour. After wet-milling, the powder was spray-granulated to obtain spherical granules. The granules were then debinded at 500°C for 4 hours, sintered at 1950°C for 2 hours in a nitrogen-filled sintering furnace, crushed, and sieved to obtain spherical aluminum nitride powder. Scanning electron micrographs of the product are shown below. Figure 1 and Figure 2 The product performance is shown in Table 1.

[0036] from Figure 1 and Figure 2 As can be seen, the spherical aluminum nitride powder has good roundness. Furthermore, the largest particle size was identified from a 68x magnification scanning electron microscope (SEM) image, and then further confirmed to be 51.1 μm in a 1000x magnification SEM image.

[0037] Example 2

[0038] 100 parts by weight of micron-sized primary aluminum nitride particles (D50=1.3μm), 100 parts by weight of acetone, 3 parts by weight of yttrium isopropoxide, 2 parts by weight of stearic acid, 2.5 parts by weight of polyvinylpyrrolidone, 0.5 parts by weight of dopamine, and 150 parts by weight of ethanol were placed in a ball mill and wet-milled for 2 hours. After wet-milling, the particles were spray-granulated to obtain spherical granulated powder. The powder was then debinded at 600℃ for 3 hours, sintered at 1900℃ for 3 hours in a nitrogen-filled sintering furnace, crushed, and sieved to obtain spherical aluminum nitride powder. The properties of the product are shown in Table 1.

[0039] Example 3

[0040] 100 parts by weight of micron-sized primary aluminum nitride particles (D50=1.4μm), 120 parts by weight of ethanol, 2.5 parts by weight of yttrium isopropoxide, 0.5 parts by weight of stearic acid, 1 part by weight of polyvinylpyrrolidone, 0.2 parts by weight of dopamine, and 150 parts by weight of ethanol were placed in a ball mill and wet-milled for 2 hours. After wet-milling, the particles were spray-granulated to obtain spherical granulated powder. The powder was then debinded at 700℃ for 2 hours, sintered at 1700℃ for 6 hours in a nitrogen-filled sintering furnace, crushed, and sieved to obtain spherical aluminum nitride powder. The properties of the product are shown in Table 1.

[0041] Example 4

[0042] 100 parts by weight of micron-sized primary aluminum nitride particles (D50=1.3μm), 110 parts by weight of ethanol, 4 parts by weight of yttrium isopropoxide, 1 part by weight of stearic acid, 0.5 parts by weight of polyvinylpyrrolidone, 0.5 parts by weight of dopamine, and 150 parts by weight of ethanol were placed in a ball mill and wet-milled for 3 hours. After wet-milling, the particles were spray-granulated to obtain spherical granulated powder. The powder was then debinded at 600℃ for 3 hours, sintered at 1800℃ for 4 hours in a nitrogen-filled sintering furnace, crushed, and sieved to obtain spherical aluminum nitride powder. The properties of the product are shown in Table 1.

[0043] Example 5

[0044] 100 parts by weight of micron-sized primary aluminum nitride particles (D50=1.2μm), 100 parts by weight of isopropanol, 4 parts by weight of yttrium isopropoxide, 1 part by weight of stearic acid, 1 part by weight of polyvinylpyrrolidone, 0.4 parts by weight of dopamine, and 150 parts by weight of ethanol were placed in a ball mill and wet-milled for 2 hours. After wet-milling, the particles were spray-granulated to obtain spherical granulated powder. The powder was then debinded at 650℃ for 2.5 hours, sintered at 1750℃ for 5 hours in a nitrogen-filled sintering furnace, crushed, and sieved to obtain spherical aluminum nitride powder. The properties of the product are shown in Table 1.

[0045] Example 6

[0046] 100 parts by weight of micron-sized primary aluminum nitride particles (D50=1.5μm), 90 parts by weight of ethanol, 4 parts by weight of yttrium isopropoxide, 1.5 parts by weight of stearic acid, 2 parts by weight of polyvinylpyrrolidone, 0.6 parts by weight of dopamine, and 150 parts by weight of ethanol were placed in a ball mill and wet-milled for 2 hours. After wet-milling, the particles were spray-granulated to obtain spherical granulated powder. The powder was then debinded at 600℃ for 2 hours, sintered at 1850℃ for 4 hours in a nitrogen-filled sintering furnace, crushed, and sieved to obtain spherical aluminum nitride powder. The properties of the product are shown in Table 1.

[0047] Comparative Example 1

[0048] 100 parts by weight of micron-sized primary aluminum nitride particles (D50=1.3μm), 110 parts by weight of ethanol, 4 parts by weight of yttrium oxide, 1.5 parts by weight of stearic acid, 2 parts by weight of polyvinylpyrrolidone, and 150 parts by weight of ethanol were placed in a ball mill and wet-milled for 1 hour. After wet-milling, the powder was spray-granulated to obtain spherical granules. The granules were then debinded at 500℃ for 4 hours and sintered at 1950℃ for 2 hours in a nitrogen-filled sintering furnace. Finally, the powder was crushed and sieved to obtain spherical aluminum nitride powder. The properties of the product are shown in Table 1.

[0049] Comparative Example 2

[0050] 100 parts by weight of micron-sized primary aluminum nitride particles (D50=1.4μm), 120 parts by weight of ethanol, 4 parts by weight of yttrium oxide, 1.5 parts by weight of stearic acid, 2 parts by weight of polyvinylpyrrolidone, 0.6 parts by weight of dopamine, and 150 parts by weight of ethanol were placed in a ball mill and wet-milled for 1 hour. After wet-milling, the powder was spray-granulated to obtain spherical granules. The granules were then debinded at 500℃ for 4 hours and sintered at 1950℃ for 2 hours in a nitrogen-filled sintering furnace. Finally, the powder was crushed and sieved to obtain spherical aluminum nitride powder. The properties of the product are shown in Table 1.

[0051] In each embodiment, the relevant performance testing methods for the product are as follows:

[0052] (1) Particle size

[0053] Before testing, clean the pipeline with compressed air (0.5 MPa), and use a dry laser particle size analyzer OMC-TopSizer to control the equipment's shading ratio between 1% and 5%.

[0054] (2) Scanning electron microscope

[0055] From SEM images at 68x magnification (Kusem EM-30, such as...) Figure 1 In the sample, the largest aluminum nitride sintered particles were selected, and their size was measured in a 1000x SEM image.

[0056] (3) Roundness

[0057] The particle size and shape analyzer was manufactured by MIP TECHNOLOGY (R-3000), and the test was conducted using the static image method. A 5mm³ measuring spoon was used to load the sample into a proprietary fixture containing an anti-static film. The 50-micrometer-thick film ruptured under a controlled vacuum, dispersing all particles into an inverted conical cavity. After standing for 60 seconds, the particles fell onto a flat glass surface due to gravity, forming a monodisperse layer. The ratio of the projected area of ​​a particle with a roundness of 4π to the square of its perimeter is calculated as: Roundness = 4 × π × Area / Perimeter. 2 Simultaneously, the R-3000 particle size and shape analyzer provides data on the percentage distribution of particles with different roundness.

[0058] Table 1 Product Performance Data

[0059] As shown in Table 1, compared with Comparative Example 1 (using yttrium oxide as a sintering aid without dopamine) and Comparative Example 2 (using yttrium oxide as a sintering aid with dopamine), Examples 1-6, which used yttrium isopropoxide and dopamine as composite modifiers, exhibited higher C-axis lattice constants. This indicates that composite modification is more conducive to the retention of the aluminum nitride phase. The higher C-axis lattice constant also indicates lower oxygen content in the aluminum nitride products, resulting in better thermal conductivity. The spherical aluminum nitride products in Examples 1-6 had lower D100 / D50 and D90 / D10 ratios, indicating a narrower particle size distribution, more concentrated size distribution, and better particle uniformity. Therefore, the composite modification of primary aluminum nitride particles with yttrium isopropoxide and dopamine can effectively optimize particle size uniformity, improve the phase stability of aluminum nitride, and thus enhance the thermal conductivity of spherical aluminum nitride.

[0060] Table 2 Performance data of micron-sized aluminum nitride particles before and after primary ball milling

[0061] As shown in Table 2, the micron-sized primary aluminum nitride particles used in this embodiment had a relatively stable C-axis lattice constant (4.9811–4.9824) before ball milling, indicating that the dissolved oxygen content in the micron-sized primary aluminum nitride particles was similar. However, after ball milling, compared with Comparative Example 1 (using yttrium oxide as a sintering aid and without dopamine) and Comparative Example 2 (using yttrium oxide as a sintering aid and with dopamine), the aluminum nitride in Examples 1–6 (using yttrium isopropoxide and dopamine as composite modifiers) had a higher C-axis lattice constant, indicating that composite modification was more beneficial to the stability of the aluminum nitride phase before sintering.

Claims

1. A method for preparing spherical aluminum nitride, characterized in that, Includes the following steps: Step S1: The primary aluminum nitride particles are mixed with dispersant, binder, dopamine, yttrium isopropoxide and organic solvent, and then wet ball milled. Step S2: Spray granulation is performed on the slurry obtained from wet ball milling in step S1 to obtain spherical granulated powder. Step S3: The spherical granulated powder obtained by spray granulation and debinding in step S2 is debinded, sintered, crushed, and sieved to obtain spherical aluminum nitride powder.

2. The method for preparing spherical aluminum nitride according to claim 1, characterized in that, In step S1, the mass ratio of the dispersant to the primary aluminum nitride particles is 1:50 to 1:

200. The mass ratio of binder to primary aluminum nitride particles is 1:40 to 1:200; The mass ratio of organic solvent to primary aluminum nitride particles is 0.9:1 to 1.3:1; And / or, in step S1, the mass ratio of dopamine to primary aluminum nitride particles is 1:100 to 1:500; The mass ratio of yttrium isopropoxide to primary aluminum nitride particles is 1:20 to 1:

40.

3. The method for preparing spherical aluminum nitride according to claim 1, characterized in that, In step S3, the temperature during glue discharge is 500℃~700℃, the atmosphere is air, and the time is 2h~4h.

4. The method for preparing spherical aluminum nitride according to claim 1, characterized in that, The sintering temperature is 1700℃~1950℃, the atmosphere is nitrogen, and the time is 2h~6h.

5. A spherical aluminum nitride powder, characterized in that, The spherical aluminum nitride particles are prepared by the method described in any one of claims 1 to 4 and are composed of primary aluminum nitride particles modified by dopamine and yttrium isopropoxide.

6. The spherical aluminum nitride powder according to claim 5, characterized in that, The ratio of aluminum nitride powder to D100 is ≤2.8, and the ratio of D90 to D10 is ≤2.

9.

7. The spherical aluminum nitride powder according to claim 5, characterized in that, The D50 of aluminum nitride powder is 20–28 μm.

8. The spherical aluminum nitride powder according to claim 5, characterized in that, The proportion of aluminum nitride powder particles with a roundness of ≥0.8 is ≥70%.

9. The spherical aluminum nitride powder according to claim 5, characterized in that, The maximum particle size of aluminum nitride powder is ≤52μm.

10. The spherical aluminum nitride powder according to claim 5, characterized in that, The C-axis lattice constant of aluminum nitride powder is ≥4.978.

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