In addition to high thermal conductivity, AIN ceramics also have the following advantages:
1 Good electrical insulation;
2 The thermal expansion coefficient is similar to that of silicon single crystal, which is better than BeO and Al2O3 materials
3 High mechanical strength, its bending strength is similar to that of Al2O3 ceramics;
4 Moderate dielectric constant and dielectric loss;
5 Compared with BeO, the thermal conductivity of AIN ceramics is less affected by temperature, especially above 200℃
6 High temperature and corrosion resistance;
7 Non-toxic
The main application areas of aluminum nitride ceramics are as follows:
(1) Semiconductor industry
The preferred use of AIN ceramics is as a large-scale integrated circuit ceramic substrate and heat dissipation substrate for high-density packaging. In the past, the substrate material was mainly Al2O3, and the thermal conductivity of AIN is 5 to 10 times that of Al2O3, which is more suitable for large-scale integrated circuit requirements. BeO ceramics have high thermal conductivity, but the toxicity of BeO powder limits its industrial application. Although diamond has excellent thermal conductivity, it is very expensive and is not suitable for use as a substrate material. Although SiC material has high thermal conductivity, it is not suitable for industrial production due to its large dielectric constant and low resistivity (once other impurities are mixed in, it can easily become a semiconductor, and the resistivity decreases). In addition, AIN ceramics can be used as trays for silicon wafer support.
(2) Chemical and metallurgical industry
AIN ceramics have good high-temperature resistance and corrosion resistance. It can coexist with many metals at high temperatures and is not wetted by many molten metals and molten salts. Therefore, it is an excellent crucible material. It can be used as a container for vacuum evaporation and smelting metals. It is particularly suitable as a crucible for vacuum evaporation of Al, because AIN has a low vapor pressure when heated in a vacuum, and even if it decomposes, it will not contaminate aluminum. AlN can also be used as a thermocouple protective cover. It can be continuously immersed in an aluminum pool at 800~1000℃ in air for more than 300 hours without corrosion damage. In addition, due to the stability of AIN to gallium arsenide, using AIN crucibles instead of quartz crucibles to synthesize gallium arsenide can eliminate the contamination of silicon in gallium arsenide and obtain high-purity products.
(3) Other industrial applications
AIN ceramics have high room temperature strength and good stability, high thermal conductivity, and low thermal expansion coefficient. They are good thermal shock-resistant and heat exchange materials and are expected to be used in gas turbine heat exchangers. They can also be used as heat-conducting annular heat-resistant disks. In addition, AIN also has excellent wear resistance and can be used as abrasive materials and wear-resistant parts. Due to their high thermal conductivity and insulation, AIN ceramics are also used as heat dissipation elements in microwave tubes and other fields.