White Papers

High Thermal Conductivity Materials: Aluminum Diamond, Aluminum Silicon Carbide, and Copper Diamond

Abstract:

Thermal management of RF amplifier devices is becoming more critical as GaN on Silicon Carbide (SiC) and GaN on Diamond devices are being produced which have high power densities that are substantially greater than previous Silicon-based devices.

The management of heat dissipation from GaN on SiC or GaN on Diamond devices to the appropriate heat spreader material presents challenges that existing materials such as Copper Tungsten, Copper Moly, and Copper Moly Copper fail to fully support and as a result these materials are limiting the performance benefits inherent to GaN. These bottlenecks include temperature de-rating of the device, power de-rating, impact on efficiency, and reliability reduction due to the inability of these materials to dissipate heat.

Heat spreader materials present a unique challenge in that they need a CTE close to the semiconductor material as well as other components in an electronic package (e.g., 4–8 ppm/K) and also have a high thermal conductivity. Existing materials achieve low CTE at the trade-off of thermal conductivity.

Development of metal matrix composite (MMC) materials with tailored CTE (4–8 ppm/K) and thermal conductivity (>450 W/m K), specifically those based on diamond particles (with thermal conductivity between 1000 and 2000 W/mK), has been continued since the early 1980s and commercialization has been watched with great interest over the years as a solution to existing thermal material limitations.

The commercial adoption of diamond-based MMCs has been limited due to cost, ability of the manufacturing base to produce volume quantities, and the ability to meet all the technical requirements necessary for the material to be truly adopted by the customer base. This chapter explains material developments that have been taken in addressing these issues and providing a high performance thermal management material that can be integrated into devices.