Beryllium oxide (BeO) supplier Brush Ceramic Products Inc., a wholly owned subsidiary of Brush Wellman Inc., has significantly improved thermal conductivity of the insulating material BeO. Labeled BW3250, it now delivers thermal conductivity (TC) of greater than 325 W/mK at room temperature, an increase of over 15% from the 285 W/mK that was previously obtainable, said the manufacturer. The benefits in heat dissipation afforded by the advancement will allow devices employing BeO to deliver higher RF outputs, noted Brush Ceramic Products.
BeO has been a core component of many high-power microwave devices for decades. Among insulating materials, it exceeds all but diamond, since its nearest competitor – aluminum nitride (AlN) – has a thermal conductivity of only 185 W/mK, while alumina (Al2O3) can only achieve a TC of 25. In addition to TC, BeO’s coefficient of thermal expansion (CTE) at 9.0 ppm/ºC is close to that of gallium arsenide (6.9), which makes it much easier to match to the devices with which it is used, added the supplier. Plus, it is also well matched to metal matrix composites as Cu/W, Cu/Mo, Al/SiC, and E-materials.
The electrical resistivity and dielectric strength of BeO is better than AlN and is similar to alumina. It has a low dielectric constant of 6.7 and a low loss index of 0.0012 at 1 MHz, which addresses the increase in losses that occur as frequency increases. In addition to these characteristics, BeO is also inherently stable in oxidizing environments, in contrast to nitrides such as AlN that decompose over time to their oxide equivalent. Finally, as an oxide ceramic, BeO is stable in oxygen and moisture-containing environments. Ceramic-to-metal joints and metalization coatings are generally strong and reliable, which is important in the design of high-reliability military systems. In addition, BeO is also about 11 times more resistant to thermal shock than alumina.
Additionally, the company has recently made other enhancements to BeO products, including the ability to produce BeO plates measuring up to 4.5 inches x 4.5 inches, which reduces cost by allowing a greater number of patterns to be created on a single plate. Advanced BW3250 is available for evaluation.
RSS
Save to Del.icio.us
Digg This
