Power Electronics Thermal Interface (PETI) with Conductive Diamond Plating

A growing number of electronic applications within the Air Force, such as devices for power conditioning and distribution, RF power amplification, and high power lasers have been identified for increased heat transfer requirements to maintain operational temperatures at acceptable levels while increasing the performance through higher power. However, this same target research that requires increased heat transfer must also produce minimal coefficient of thermal expansion (CTE) variations of the inevitable dissimilar die attach interface materials used in the process. Proposed target heat transfer capabilities are consistent with the following proposed goals: 1.) 30-70 W/(m-k), or 0.3-0.7 W/(m-K), with no delamination for 500 temp cycles from -20 degree C to +250 degree C, 2.) Laboratory demonstration of proposed die attach and heat spreader materials/processes, 3.) Similar form and fit interface materials and processes for devices consistent with various power devices and conventional heat transfer substrates – target CTE mismatches as low as possible between silicon/oxides (3 – 6 ppm/°C) and metal substrates (15 – 30 ppm/°C), 4.) Since diamond is the highest heat conducting material available, and also possesses one of the lowest CTE variations over temperature, incorporating diamond into a die attach and heat spreader process is the ultimate goal.