Wednesday, September 10, 2014

Aluminum Nitride Ceramic Heaters Open Doors to Better Machine Design

Aluminum Ceramic Heaters
Aluminum Ceramic Heaters
(Courtesy of Durex)
Aluminum Nitride (AlN) Ceramic heaters are a relatively new entry in the very high watt density heater market and are an attractive alternative to traditional metal sheathed heaters. Capable of achieving up to 2000 watts per square inch, and operating temperatures of up to 1000 deg. C, these heaters show great promise for semiconductor processing applications such as crucible heating, fluid and gas handling and chemical vapor deposition. 

The heaters are made by "tracing" a resistance material (Tungsten) on a the ceramic base at various thicknesses, corresponding to the performance requirements of the heater. The Tungsten and AIN expand and contract at very similar rates, which greatly reduces the mechanical concerns of delamination. Binders and trace additives are added to the ceramic and Tungsten for additional strength. The resulting construction allows for some pretty impressive thermal cycling - one example is an application with a 200 deg. C temperature swing every 30 seconds.

AIN ceramic heaters offer significant advantages over metal sheathed heaters and their inherent performance limitations. Material compatibility, fatigue, outgassing and thermal lag must be considered when applying metal sheath heaters. Ceramic heaters combine excellent thermal conductivity with outstanding chemical resistance, strength, inertness and design flexibility. Additionally, RTD sensors can be deposited right on the ceramic heater itself for optimum control. 

Capable of forming virtually any shape, along with their excellent mechanical, thermal, dielectric, chemical resistant and embedded sensors, Aluminum Nitride Ceramic heaters open the doors for engineers to design equipment to new levels of performance.