5 September 2011

NMIC launches first aluminum diamond heat spreader material for GaN devices

Nano Materials International Corp (NMIC) of Tucson, AZ, USA has launched what it claims is the first commercial device-level solution for dissipating the heat generated by high-density semiconductor devices such as gallium nitride (GaN) RF power transistors.

When used as a heat spreader integrated with a device, NMIC's new aluminum diamond metal matrix composites (MMCs) have demonstrated their ability to reduce junction temperatures by up to 25%, allowing the devices to generate their full power output at their highest efficiency and potentially extend their operating life, says NMIC. The firm claims that it is the first aluminum diamond MMC material to be economically viable in high volume at a cost that adds minimally to each GaN device.

GaN can generate high levels of RF power over broad frequency ranges well into the millimeter-wave range. GaN devices therefore have much higher power density than other technologies such as gallium arsenide (GaAs), silicon, and silicon germanium (SiGe), as measured by the amount of power they can generate in a given amount of device gate periphery.

However, this power density also results in the production of large amounts of waste heat that must be removed from the device, a challenge that must be met effectively if GaN technology is to achieve its full potential, NMIC says.

Diamond has the highest thermal conductivity of any substance on Earth. When made as an aluminum diamond composite and used as a heat spreader material, this property remains about 80% higher than its nearest competitor copper-molybdenum-copper, which is widely used for this purpose. Aluminum diamond also has a coefficient of thermal expansion (CTE) close to that of silicon carbide (SiC), which is essential as most GaN devices employ SiC as their substrate material. NMIC says that its aluminum diamond also has metallization properties well suited for die attach, along with excellent dimensional tolerance and material stability.

The MMC material, with nickel-gold electrolytic or electroless plating, is available in thicknesses, shapes, and sizes required by GaN transistors or microwave monolithic integrated circuits (MMICs). It can be supplied as MMC material alone or incorporated within a package in order to serve the needs of device manufacturers and package suppliers.

Tags: GaN RF power transistors

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