Aluminum nitride (AlN) is a technical ceramic material that features an extremely interesting combination of very high thermal conductivity and excellent electrical insulation properties. It has a hexagonal crystal structure and is a covalent bonded material. The use of sintering aids and hot pressing is required to produce a dense technical grade material. The material is stable to very high temperatures in inert atmospheres. In air, surface oxidation begins above 700°C. A layer of aluminum oxide forms which protects the material up to 1370°C. Above this temperature bulk oxidation occurs. Aluminum nitride is stable in hydrogen and carbon dioxide atmospheres up to 980°C. The material dissolves slowly in mineral acids through grain boundary attack, and in strong alkalis through attack on the aluminum nitride grains. The material hydrolyzes slowly in water. Most current applications are in the electronics area where heat removal is important. This material is of interest as a non-toxic alternative to beryllia. Metallization methods are available to allow AlN to be used in place of alumina and BeO for many electronic applications.
Properties
Good dielectric properties
High thermal conductivity
Low thermal expansion coefficient, close to that of Silicon
Non-reactive with normal semiconductor process chemicals and gases
Application
Substrates for electronic packages
Heat sinks
IC packages
Power transistor bases
Microwave device packages
Material processing kiln furniture
Semiconductor processing chamber fixtures and insulators
Molten metal handling components
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