technical ceramic solutions

Why Aluminum Nitride Heater Plate Is Very Difficult To Make

Aluminum nitride ceramic heating plates are widely used in the semiconductor industry. The size is generally 8 inches. The demand for aluminum nitride ceramic heating plates is very tight, but there are very few manufacturers that can process aluminum nitride ceramic heating plates. The main reason is that the aluminum nitride ceramic heating plate is very difficult to process. So why is the aluminum nitride ceramic heating plate difficult to process?

AlN Heater Plate

First, we need to understand what the aluminum nitride ceramics are:


Experts in the ceramic industry know that aluminum nitride ceramics are advanced ceramic materials that have high thermal conductivity and electrical insulation properties and are widely used in the electronics industry.


Aluminum nitride crystal belongs to the hexagonal crystal system. It is a covalently bonded compound with tetrahedron as the structural unit and has a wurtzite structure. At the same time, it is also a high-temperature resistant ceramic material. Its single crystal thermal conductivity is about 5 times that of alumina. It can be used in an environment of 2200°C and has good thermal shock resistance.


At the same time, aluminum nitride is resistant to corrosion by metals in the molten state and is almost unstable by acids. Because the aluminum nitride surface reacts to form an extremely thin oxide film when exposed to moist air, takeing advantage of this property and use it as a crucible and firing mold material for the smelting of aluminum, copper, silver, lead and other metals. Also because aluminum nitride ceramics have better metallization properties, they can replace toxic beryllium oxide ceramics and are widely used in the electronics industry.


The chemical formula of aluminum nitride is AlN, and its chemical composition is about 65.81% AI and 34.19% N. Its powder is generally white or off-white, and it is colorless and transparent in the single crystal state. Its sublimation decomposition temperature under normal pressure reaches 2450°C.


The thermal conductivity of aluminum nitride ceramics is between 170~210 W / (m.k), and the thermal conductivity of single crystal can be as high as 275 W / (m.k) or more. High thermal conductivity (>170W/m·K), close to BeO and SiC; thermal expansion coefficient (4.5×10-6℃) is similar to Si (3.5~4×10-6℃) and GaAs (6×10-6℃) Matching; excellent various electrical properties (dielectric constant, dielectric loss, volume resistivity, dielectric strength); good mechanical properties, higher flexural strength than Al2O3 and BeO ceramics, can be sintered at normal pressure; can be produced by tape casting process.


Aluminum nitride ceramics is a hard and brittle material. It is very difficult to process after sintered. Its various properties are superior to other ceramic materials, which also means that its processing difficulty is higher than other ceramics. There is another fatal difficulty in processing aluminum ceramics which is it is very brittle and very easy to have white edges.


Under this circumstance, it has become extremely difficult to make ceramic heating plates from aluminum nitride. An 8-inch aluminum nitride ceramic heating plate is approximately a disc with a diameter of 315mm and a thickness of 19mm. The aluminum nitride material used to make the heating plate needs to be larger than this size. In the processing industry, this size is very large. In the processing center It is very easy to damage the entire material when the slot is empty.


The processing cost of such a large aluminum nitride ceramic material is very high. If there is a slight problem in a certain detail, the entire material will be scrapped. So the risk is also very high when processing aluminum nitride heating plates. If a piece of material is damaged, the manufacturer will lose all its money, so many manufacturers are not willing to take this risk, which results in very few manufacturers processing aluminum nitride heating plates.