Aluminum Nitride Ceramic (AlN Ceramic) is an advanced ceramic material with aluminum nitride (AlN) as the main component. Aluminum nitride is a covalently bonded compound with a hexagonal wurtzite crystal structure and belongs to the hexagonal crystal system.
Aluminum nitride ceramics are prepared by powder metallurgy and made into high-density, high-performance ceramic products through molding, sintering and other processes.
Aluminum nitride ceramics have become core materials in high-end electronics, semiconductors, aerospace and biomedicine due to their excellent thermal, electrical, mechanical and chemical properties.
Overview
Aluminum nitride ceramics are compounds composed of aluminum (Al) and nitrogen (N) elements (chemical formula AlN) with a hexagonal wurtzite crystal structure. Its preparation usually adopts powder metallurgy process, and densification is achieved through high temperature sintering (1700-1900°C) and adding sintering aids (such as Y₂O₃). AlN is known for its high thermal conductivity, excellent insulation and chemical stability, and is an important material in the field of advanced ceramics.
Properties of aluminum nitride ceramics:
1. Thermal properties:
High thermal conductivity: The theoretical thermal conductivity of aluminum nitride ceramics can reach 320 W/(m·K), and the actual product thermal conductivity is usually between 170-260 W/(m·K), which is much higher than alumina ceramics (about 30 W/(m·K)).
Low thermal expansion coefficient: The thermal expansion coefficient is (4.0-6.0)×10⁻⁶/℃, which matches well with silicon (3.5-4.2×10⁻⁶/℃) and gallium arsenide (6×10⁻⁶/℃), and is suitable for semiconductor packaging applications.
High temperature resistance: The melting point is as high as 2200℃, and it maintains stable physical and chemical properties in high temperature environment.
2. Electrical properties:
High insulation: The volume resistivity is up to 10¹⁶ Ω·cm, the dielectric constant is about 8.9 (1 MHz), and the dielectric loss (1 MHz) is (3-10)×10⁻⁴, which is suitable for high-frequency electronic devices.
High breakdown voltage: The voltage resistance exceeds 15 kV/mm, ensuring the reliability of electrical insulation.
3. Mechanical properties:
High hardness: The Mohs hardness is 7-8, second only to diamond and cubic boron nitride, and has excellent wear resistance.
High strength: The flexural strength is more than 300 MPa, and the Young's modulus is about 308 GPa, which is suitable for high-load structural parts.
4. Chemical properties:
Corrosion resistance: It has good corrosion resistance to acids, alkalis and molten metals (such as aluminum and copper), but it is easy to react with strong alkaline solutions.
Stability: Aluminum oxide protective film is formed in the air and at high temperature to prevent further oxidation..
Advantages of aluminum nitride ceramics:
1. Superior comprehensive performance: It has high thermal conductivity, high insulation, high strength and low thermal expansion coefficient, meeting the stringent requirements of electronic devices for heat dissipation, insulation and mechanical stability.
2. Lightweight potential: The density is only 3.26 g/cm³, which is lower than aluminum oxide (about 3.95 g/cm³) and silicon nitride (about 3.21 g/cm³), suitable for weight-sensitive applications.
3. Environmental protection and non-toxicity: Aluminum nitride ceramics are non-toxic and harmless, meet environmental protection requirements, and are suitable for biomedical and food processing fields.
4. Optical properties: Pure aluminum nitride ceramics are transparent in the ultraviolet and visible light ranges and can be used for infrared windows and lenses..
Applications of aluminum nitride ceramics:
1. Electronic packaging and heat dissipation:
Large-scale integrated circuit substrates: Use high thermal conductivity and low thermal expansion coefficient to solve chip heat dissipation and thermal stress problems.
Power semiconductor devices: As heat dissipation substrates and packaging materials, they improve the reliability and life of power modules.
High-power LED packaging: effectively reduce the operating temperature of LED chips, improve light efficiency and stability.
2. Semiconductor manufacturing:
Electrostatic chuck: used for semiconductor wafer processing, providing uniform clamping force and thermal management.
Heating plate and ceramic nozzle: used in plasma etching and deposition equipment to ensure temperature uniformity and corrosion resistance.
3. Optics and optoelectronics
Infrared windows and lenses: achieve high transmittance and high temperature resistance in infrared detectors, lasers and thermal imagers.
UV LED substrate: supports the luminous efficiency and service life of high-power UV LEDs.
4. Aerospace and defense
High-temperature structural parts: used in rocket engine nozzles, aircraft shells, etc., to withstand extreme high temperatures and mechanical stress.
Radar and communication systems: as microwave window materials, to ensure the stability of high-frequency signal transmission.
5. Energy and environmental protection
Fuel cell catalyst carrier: use high specific surface area and chemical stability to improve fuel cell efficiency.
High-temperature turbine components: withstand high-temperature corrosive environments in gas turbines and internal combustion engines.
6. Biomedicine
Implant materials: good biocompatibility and mechanical properties, suitable for artificial joints and dental implants.
Biosensors: as the base material of sensor elements, high sensitivity and stability are achieved.
Aluminum nitride ceramics continue to expand their applications in high-end electronics, new energy and other fields due to their unique properties, and are an important direction for high thermal conductivity materials in the future..
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