Thermal Management

The increased density of electronic components and subsystems in military electronic systems exacerbates the thermal management challenges facing engineers. The military platforms that host these systems often cannot physically accommodate the large cooling systems needed for thermal management, meaning that heat can be a limiting factor for performance of electronics and embedded computers.

Many military radio frequency (RF) systems, like radar and communication systems, use a class of power amplifiers (PAs) called monolithic microwave integrated circuits (MIMIC). MMIC PAs using gallium nitride (GaN) transistors hold great promise for enhanced RF performance, but operational characteristics are strongly affected by thermal resistance. Much of this resistance comes at the thermal junction where the substrate material of the circuit connects to the GaN transistor. If the junction and substrate have poor thermal properties, temperature will rise and performance will decrease.

The increased density of components in today’s electronics has pushed heat generation and power dissipation to unprecedented levels. Current thermal management solutions, usually involving remote cooling, where heat must be conducted away from components before rejection to the air, are unable to limit the temperature rise of today’s complex electronic components without adding considerable weight and volume to electronic systems. The result is complex military systems that continue to grow in size and weight due to the inefficiencies of existing thermal management hardware.

Significant enhancements in fundamental device materials, technologies and system integration have led to rapid increases in the total power consumption of DoD systems. In many cases, power consumption has increased while system size has decreased, leading to an even greater problem with heat density. Thermal management of DoD systems often imposes the main obstacle to further enhancements.

As electronic system technology advances – with continual increases in requirements leading to increasing demand for higher power consumption – there has been increasing pressure on the thermal engineering and heat rejection technologies used. DoD systems are driving conflicting needs for high performance as well as reduced size and weight. DARPA makes many investments in new technologies that can improve performance or reduce size and weight.