Novel high-purity, high-resistance and high-thermal-conductivity aluminum oxide and preparation method thereof

Abstract

The invention relates to the technical field of inorganic non-metallic materials, in particular to novel high-purity high-resistance high-thermal-conductivity aluminum oxide and a preparation method thereof, and the novel high-purity high-resistance high-thermal-conductivity aluminum oxide is prepared from high-purity aluminum oxide powder through dispersion treatment, spray drying, segmented sintering and surface modification. The aluminum oxide content of the obtained material is greater than or equal to 99.99%, the resistivity is greater than or equal to 101-omega.cm, the heat conductivity coefficient is greater than or equal to 30W / m.K, the compressive strength is greater than or equal to 200MPa, and the bending strength is greater than or equal to The comprehensive performance of the material is remarkably improved by optimizing the process, and the material has excellent electrical insulating property, thermal conductivity and mechanical strength, is suitable for the fields of high-end electronic packaging, semiconductor devices and efficient thermal management, and meets the requirements of complex working conditions.

Description

Technical Field

[0001] This invention belongs to the field of inorganic non-metallic materials technology, specifically a novel high-purity, high-resistivity, and high-thermal-conductivity alumina and its preparation method. Background Technology

[0002] Alumina, as an important inorganic non-metallic material, is widely used in electronic packaging, semiconductor devices, and efficient thermal management due to its excellent thermal conductivity, electrical insulation, and chemical stability. Especially in modern electronic devices and high-performance semiconductor devices, alumina is widely used in key components such as substrates, heat sinks, and insulating layers to meet stringent requirements for thermal management, electrical insulation, and mechanical strength. However, as electronic devices evolve towards miniaturization, integration, and high performance, the shortcomings of traditional alumina materials in terms of purity, resistivity, and thermal conductivity are becoming increasingly apparent, making it difficult to fully meet the demands of high-end applications.

[0003] Currently, commonly available alumina materials typically suffer from the following problems: First, in terms of purity, traditional alumina materials have a high impurity content, resulting in poor stability and reliability in high-end applications. For example, trace amounts of impurities such as iron and sodium can significantly reduce the material's electrical insulation performance and chemical stability, thus affecting the long-term lifespan of devices. Second, in terms of resistivity, traditional alumina materials generally have low resistivity, making it difficult to meet the high electrical insulation requirements of high-performance electronic devices. Especially in high-frequency, high-voltage operating environments, low resistivity may lead to increased leakage current, thereby affecting the normal operation of devices. Furthermore, in terms of thermal conductivity, traditional alumina materials have a relatively low thermal conductivity, failing to effectively meet the demands of modern electronic equipment for efficient thermal management. This not only limits the heat dissipation efficiency of devices but may also lead to localized overheating, further affecting the reliability and lifespan of devices.

[0004] To address these issues, researchers have conducted extensive research in recent years on the preparation processes and performance optimization of alumina materials. For example, by improving raw material selection, optimizing sintering processes, and introducing surface modification techniques, the purity, resistivity, and thermal conductivity of alumina materials can be improved to some extent. However, existing technologies still have many shortcomings. On the one hand, traditional preparation processes often struggle to simultaneously achieve high purity, high resistivity, and high thermal conductivity, limiting the overall improvement of material performance. On the other hand, existing technologies often face problems such as high cost and complex processes in practical applications, making large-scale industrial production difficult. Furthermore, while some studies have achieved good performance improvements under laboratory conditions, in practical applications, environmental factors (such as high temperature and humidity) can easily cause material performance degradation, making it difficult to meet the requirements for long-term stable operation. Summary of the Invention

[0005] Therefore, developing an alumina material with high purity, high resistivity, and high thermal conductivity, and providing an efficient and stable preparation method, has become a pressing technical challenge in the field of inorganic non-metallic materials.

[0006] This invention proposes a novel high-purity, high-resistivity, and high-thermal-conductivity alumina and its preparation method by optimizing material composition and preparation process. This method significantly improves the comprehensive performance of the alumina material through systematic optimization of key steps such as raw material selection, ball milling, molding and drying, high-temperature sintering, and surface modification. The invention uses high-purity alumina as raw material and optimizes the powder particle size distribution by precisely controlling ball milling time and speed. In the molding and drying stage, a pressing or slip casting process is used, combined with low-temperature drying technology, to ensure the uniformity and stability of the material structure. During high-temperature sintering, the thermal conductivity and resistivity of the material are further improved by adjusting the sintering temperature and time. Finally, the surface characteristics and interfacial properties of the material are further optimized by introducing silane coupling agents or titanate coupling agents for surface modification. The alumina material prepared by this invention not only possesses high purity (≥99.98%), high resistivity (≥10¹¹ Ω·cm), and high thermal conductivity (≥25 W / m·K), but also exhibits excellent chemical stability and mechanical strength, making it suitable for high-end fields such as electronic packaging, semiconductor devices, and efficient thermal management.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A novel method for preparing high-purity, high-resistivity, and high-thermal-conductivity alumina, comprising the following steps:

[0009] Step 1: Mix high-purity alumina powder with a dispersant, add deionized water, and then disperse and stir the powder evenly to form a slurry.

[0010] Step 2: Spray dry the slurry obtained in Step 1 to form pre-granulated alumina powder at a specific temperature;

[0011] Step 3: Place the particles obtained in Step 2 into a high-temperature furnace for segmented sintering. In the first stage, moisture and organic residues are removed at low temperature. In the second stage, the crystal structure is optimized at high temperature to improve thermal conductivity and resistivity.

[0012] Step 4: The particles obtained in Step 3 are graded and screened, and the particle surface is modified with a chemical modifier to finally obtain the finished powder within the target particle size range.

[0013] This invention significantly improves the overall performance of alumina materials through dispersion treatment, segmented sintering, and surface modification. The prepared alumina material exhibits high purity (≥99.99%), high resistivity (≥10¹□Ω·cm), high thermal conductivity (≥30W / m·K), and excellent mechanical strength (compressive strength ≥200MPa, flexural strength ≥100MPa). Furthermore, this material maintains excellent chemical stability under high temperature and humid conditions, making it suitable for the stringent requirements of high-end electronic packaging, semiconductor devices, and efficient thermal management.

[0014] In step 1, the dispersant is at least one of sodium polyacrylate, polyvinylpyrrolidone, or carboxymethyl cellulose, preferably sodium polyacrylate; the ultrasonic dispersion time is 10 to 30 minutes, and the stirring speed is 500 to 800 rpm, preferably 600 rpm.

[0015] In step 2, the spray drying temperature is 250–350°C, and the feed rate is 10–20 mL / min, preferably 15 mL / min.

[0016] In step 3, the first stage sintering temperature is 150-250℃ and the holding time is 1-2 hours; the second stage sintering temperature is 1500-1700℃ and the holding time is 3-5 hours, preferably 4 hours at 1600℃.

[0017] In step 4, the grading and screening adopts air classification or vibrating sieving process, and the target particle size range is 10 to 100 μm; the chemical modifier is a silane coupling agent or a titanate coupling agent, and the addition amount is 0.5% to 1.5%, preferably 1%.

[0018] The present invention also provides a novel high-purity, high-resistivity, and high-thermal-conductivity alumina, wherein the alumina material is prepared by the preparation method described in the present invention;

[0019] The alumina material has a resistivity ≥101□Ω·cm, a thermal conductivity ≥30W / m·K, a compressive strength ≥200MPa, a flexural strength ≥100MPa, and a particle size distribution range of 10~100μm.

[0020] The following are relevant embodiments and comparative examples:

[0021] Example 1:

[0022] Raw material: High-purity alumina (Al2O3 content ≥ 99.99%).

[0023] Dispersion treatment: Sodium polyacrylate was used as a dispersant and ultrasonically dispersed for 20 minutes at a stirring speed of 600 rpm.

[0024] Spray drying: temperature 300℃, feed rate 15mL / min.

[0025] Sintering: First stage: hold at 200℃ for 1.5 hours; second stage: hold at 1600℃ for 4 hours.

[0026] Surface modification: 1% silane coupling agent was added.

[0027] Example 2:

[0028] Raw material: High-purity alumina (Al2O3 content ≥ 99.98%).

[0029] Dispersion treatment: Polyvinylpyrrolidone was used as a dispersant, and ultrasonic dispersion was performed for 30 minutes at a stirring speed of 800 rpm.

[0030] Spray drying: temperature 350℃, feed rate 20mL / min.

[0031] Sintering: First stage: hold at 250℃ for 2 hours; second stage: hold at 1700℃ for 3 hours.

[0032] Surface modification: treated with titanate coupling agent, with an addition amount of 0.5%.

[0033] Comparative Example 1:

[0034] Raw material: Ordinary industrial grade alumina (Al2O3 content ≥99.5%).

[0035] It was spray-dried directly without any dispersion treatment.

[0036] Sintering: Single stage, 1500℃, held for 5 hours.

[0037] No surface modification treatment was performed.

[0038] Comparative Example 2:

[0039] Raw material: High-purity alumina (Al2O3 content ≥ 99.99%).

[0040] Dispersion process: Only stirring was used; ultrasonic dispersion was not performed.

[0041] Spray drying: temperature 250℃, feed rate 10mL / min.

[0042] Sintering: First stage: hold at 150℃ for 1 hour, second stage: hold at 1500℃ for 3 hours.

[0043] Surface modification: No chemical modification treatment was performed.

[0044] The comparison table of indicators is as follows:

[0045] index Example 1 Example 2 Comparative Example 1 Comparative Example 2 Test methods Alumina content (%) ≥99.99 ≥99.98 ≥99.5 ≥99.99 X-ray fluorescence spectroscopy analysis Resistivity (Ω·cm) <![CDATA[≥10 14 ]]> <![CDATA[≥10 13 ]]> <![CDATA[≤10 12 ]]> <![CDATA[≤10 13 ]]> resistivity tester Thermal conductivity (W / m·K) ≥30 ≥25 ≤20 ≤22 Laser flash method Compressive strength (MPa) ≥200 ≥150 ≤100 ≤120 Compressive strength tester Flexural strength (MPa) ≥100 ≥80 ≤50 ≤60 Bending strength tester <![CDATA[Density (g / cm 3 )]] 3.9-4.0 3.8-3.9 3.5-3.6 3.6-3.7 Densitometer measurement method Moisture content (%) ≤0.1 ≤0.2 ≥0.5 ≥0.3 Karl Fischer

[0046] Compared with the prior art, the beneficial effects of the present invention are:

[0047] (1) High purity: By strictly controlling raw materials and dispersion process, the alumina content is ensured to be ≥99.99%, which is suitable for high-end applications.

[0048] (2) High resistivity: By optimizing the segmented sintering process and surface modification treatment, the resistivity of the material is significantly improved, making it suitable for the field of electrical insulation.

[0049] (3) High thermal conductivity: By optimizing the crystal structure and sintering process, the thermal conductivity is significantly improved, making it suitable for high-efficiency thermal management materials.

[0050] (4) Chemical stability: It can maintain stable performance under high temperature and humid environment, thus extending the service life of the material.

[0051] (5) High mechanical strength: It has good compressive and bending resistance and is suitable for complex working conditions. Attached Figure Description

[0052] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0053] In the attached diagram:

[0054] Figure 1 This is a flowchart illustrating the steps involved in preparing a novel high-purity, high-resistivity, and high-thermal-conductivity alumina. Detailed Implementation

[0055] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0057] This invention relates to a novel high-purity, high-resistivity, and high-thermal-conductivity alumina and its preparation method, in conjunction with the attached... Figure 1The process flow diagram provides a detailed explanation of the specific implementation method. (See attached diagram.) Figure 1 The key steps—dispersion treatment, spray drying, segmented sintering, and surface modification—are clearly marked and collectively constitute the core flow of the entire preparation process. The following sections will elaborate on the raw material selection, the operating principles of each process step, and the actual operation process, and demonstrate its application effects in high-end electronic packaging, semiconductor devices, and efficient thermal management through specific examples.

[0058] Firstly, regarding raw material selection, this invention uses high-purity alumina powder as the base material, requiring an alumina content ≥99.99% to ensure the high purity of the final product. Furthermore, to improve the dispersibility of the powder, an appropriate amount of dispersant needs to be added. The dispersant can be selected from at least one of sodium polyacrylate, polyvinylpyrrolidone, or carboxymethyl cellulose, with sodium polyacrylate being preferred. The dispersant's role is to prevent particle agglomeration by adsorbing onto the surface of the powder particles and forming a protective layer. The amount of dispersant added is typically 0.5% to 1.5% of the powder mass, and the optimal ratio is determined through experimental optimization. At this stage, deionized water is introduced as a solvent to ensure the purity and stability of the system.

[0059] Dispersion is the first step in the preparation process and a crucial step determining subsequent performance. High-purity alumina powder is mixed with a dispersant and then deionized water is added to form an initial slurry. Subsequently, the slurry is treated using a combination of ultrasonic dispersion and mechanical stirring. The ultrasonic dispersion time is controlled between 10 and 30 minutes, preferably 20 minutes, with a frequency typically between 20 kHz and 40 kHz, effectively breaking down van der Waals forces and electrostatic interactions between particles, resulting in uniform powder dispersion. Simultaneously, the mechanical stirring speed is set to 500 to 800 rpm, preferably 600 rpm, to further promote slurry homogenization. After this step, the slurry exhibits a uniform and stable suspension state, laying a solid foundation for subsequent processes.

[0060] Next comes the spray drying stage. Spray drying is a highly efficient granulation technology aimed at converting the slurry into pre-granulated alumina powder. Specific operating parameters for spray drying include temperature and feed rate. The temperature range for spray drying is set between 250 and 350°C, preferably 300°C, to ensure rapid evaporation of moisture without damaging the powder structure. The feed rate is controlled at 10 to 20 mL / min, preferably 15 mL / min, to maintain equipment stability and powder uniformity. Under high-temperature conditions, the moisture in the slurry evaporates rapidly, resulting in particles with a high specific surface area and good flowability, providing an ideal precursor for subsequent sintering.

[0061] Segmented sintering is one of the core processes of this invention, aiming to improve the overall performance of the material by optimizing the crystal structure and removing impurities. Segmented sintering consists of two stages: the first stage involves low-temperature removal of moisture and residual organic matter, and the second stage involves high-temperature optimization of the crystal structure. The sintering temperature for the first stage is set at 150 to 250°C, with a holding time of 1 to 2 hours, preferably at 200°C for 1.5 hours. In this stage, residual moisture and organic components such as dispersants in the slurry are completely removed, avoiding potential defects such as bubbles or cracks that may occur at high temperatures. The sintering temperature for the second stage is set at 1500 to 1700°C, with a holding time of 3 to 5 hours, preferably at 1600°C for 4 hours. High-temperature sintering not only promotes the growth of alumina grains but also significantly improves the density and thermal conductivity of the material. Through the segmented sintering process, the crystal structure of the material is optimized, achieving a thermal conductivity of over 30 W / m·K and a resistivity of over 101 □Ω·cm.

[0062] Surface modification is the final step in the preparation process, aiming to further improve the surface properties of the powder through chemical modification. After grading and screening, the particles need to undergo surface modification to enhance their compatibility and dispersibility with other materials. Silane coupling agents or titanate coupling agents can be used as surface modifiers, added at a rate of 0.5% to 1.5% of the powder mass, preferably 1%. The modifier reacts with the powder surface through chemical bonding to form a uniform modified layer, thereby reducing interparticle friction and improving its moisture resistance. The surface-modified powder exhibits better flowability and chemical stability, making it suitable for long-term use under complex operating conditions.

[0063] To verify the actual effect of the above process, this invention designed several embodiments and comparative examples. Example 1 used high-purity alumina powder (Al2O3 content ≥ 99.99%), sodium polyacrylate as the dispersant, ultrasonic dispersion time of 20 minutes, and stirring speed of 600 rpm. Spray drying temperature was 300℃, and feed rate was 15 mL / min. The first stage of segmented sintering was held at 200℃ for 1.5 hours, and the second stage was held at 1600℃ for 4 hours. A silane coupling agent was used as the surface modifier, with an addition amount of 1%. Testing showed that the alumina material prepared in this example exhibited excellent comprehensive properties, with an alumina content ≥ 99.99%, resistivity ≥ 101 □Ω·cm, thermal conductivity ≥ 30 W / m·K, compressive strength ≥ 200 MPa, flexural strength ≥ 100 MPa, particle size distribution ranging from 10 to 100 μm, and a density of 3.9 to 4.0 g / cm³. 3 The moisture content of the alumina material does not exceed 0.1%.

[0064] Example 2 adjusted some parameters, such as using polyvinylpyrrolidone as the dispersant, ultrasonic dispersion time of 30 minutes, and stirring speed of 800 rpm. The spray drying temperature was 350°C, and the feed rate was 20 mL / min. The first stage of segmented sintering was held at 250°C for 2 hours, and the second stage was held at 1700°C for 3 hours. A titanate coupling agent was used as the surface modifier, with an addition amount of 0.5%. Although the performance was slightly lower than that of Example 1, it was still superior to the material prepared by the conventional process.

[0065] Comparative Example 1 used ordinary industrial-grade alumina powder (Al2O3 content ≥ 99.5%), without dispersion treatment, and underwent single-stage sintering (1500℃ for 5 hours) without surface modification. Test results showed that the alumina content of this material was only 99.5%, resistivity ≤ 10¹¹ Ω·cm, thermal conductivity ≤ 20 W / m·K, compressive strength ≤ 100 MPa, and flexural strength ≤ 50 MPa, all of which were far lower than those of the embodiments of this invention. Comparative Example 2, although using high-purity alumina powder (Al2O3 content ≥ 99.99%), only used stirring for dispersion treatment, without ultrasonic dispersion and surface modification treatment. While its performance was better than Comparative Example 1, it still could not reach the level of the embodiments.

[0066] Comparative analysis reveals that the preparation method of this invention has significant advantages in the following aspects: First, high purity: through strict control of raw materials and dispersion processes, the alumina content is ensured to be ≥99.99%, meeting the requirements of high-end applications. Second, high resistivity: through optimized segmented sintering processes and surface modification treatments, the electrical insulation performance of the material is significantly improved. Third, high thermal conductivity: through optimized crystal structure and sintering processes, the thermal conductivity of the material is significantly improved. Fourth, chemical stability: the material maintains excellent performance under high temperature and humid environments, extending its service life. Fifth, high mechanical strength: it has good compressive and bending resistance, making it suitable for complex working conditions.

[0067] In summary, this invention has successfully developed a novel high-purity, high-resistivity, and high-thermal-conductivity alumina material by optimizing raw material selection, dispersion processing, segmented sintering technology, and surface modification processes. This material has broad application prospects in high-end electronic packaging, semiconductor devices, and efficient thermal management. Its preparation method is simple, efficient, and easily scalable for industrial production.

[0068] The above description is a detailed description of the preferred embodiments of the present invention. However, the embodiments are not intended to limit the scope of the patent application of the present invention. All equivalent changes or modifications made under the technical spirit of the present invention should fall within the patent scope covered by the present invention.

Claims

1. A method for preparing a novel high-purity, high-resistivity, and high-thermal-conductivity alumina, characterized in that, Includes the following steps: Step 1: Mix high-purity alumina powder with a dispersant, add deionized water, and then disperse and stir using ultrasonic waves to form a uniform slurry; Step 2: Spray dry the slurry obtained in Step 1 to form pre-granulated alumina powder at a specific temperature; Step 3: Place the particles obtained in Step 2 in a high-temperature furnace for segmented sintering. In the first stage, hold at 150 to 250°C for 1 to 2 hours to remove moisture and organic residues. In the second stage, hold at 1500 to 1700°C for 3 to 5 hours to optimize the crystal phase structure. Step 4: The particles obtained in Step 3 are graded and screened, and the particle surface is modified with a chemical modifier to obtain finished powder within the target particle size range.

2. The method for preparing a novel high-purity, high-resistivity, and high-thermal-conductivity alumina according to claim 1, characterized in that, The dispersant is at least one of sodium polyacrylate, polyvinylpyrrolidone, or carboxymethyl cellulose.

3. The method for preparing a novel high-purity, high-resistivity, and high-thermal-conductivity alumina according to claim 1, characterized in that, The ultrasonic dispersion time is 10 to 30 minutes, and the stirring speed is 500 to 800 rpm.

4. The preparation method according to claim 1, characterized in that, The spray drying temperature is 250 to 350°C, and the feed rate is 10 to 20 mL / min.

5. The method for preparing a novel high-purity, high-resistivity, and high-thermal-conductivity alumina according to claim 1, characterized in that, The first stage of the segmented sintering is at a temperature of 200°C and a holding time of 1.5 hours, while the second stage is at a temperature of 1600°C and a holding time of 4 hours.

6. The method for preparing a novel high-purity, high-resistivity, and high-thermal-conductivity alumina according to claim 1, characterized in that, The grading and screening process employs airflow grading or vibrating sieving, with a target particle size range of 10 to 100 μm.

7. The method for preparing a novel high-purity, high-resistivity, and high-thermal-conductivity alumina according to claim 1, characterized in that, The chemical modifier is a silane coupling agent or a titanate coupling agent, and the amount added is 0.5% to 1.5% of the powder mass.

8. The method for preparing a novel high-purity, high-resistivity, and high-thermal-conductivity alumina according to claim 1, characterized in that, The high-purity alumina powder has an alumina content of not less than 99.99%.

9. A novel high-purity, high-resistivity, and high-thermal-conductivity alumina, characterized in that, The alumina material is prepared by the preparation method according to any one of claims 1 to 8, wherein the resistivity of the alumina material is not less than 101 □Ω·cm, the thermal conductivity is not less than 30 W / m·K, the compressive strength of the alumina material is not less than 200 MPa, the flexural strength of the alumina material is not less than 100 MPa, the particle size distribution range of the alumina material is 10 to 100 μm, and the density of the alumina material is 3.9 to 4.0 g / cm³. 3 The moisture content of the alumina material does not exceed 0.1%.

10. The alumina material according to claim 9, characterized in that, The alumina material is used in high-end electronic packaging, semiconductor devices, and high-efficiency thermal management.

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