Electronics thermal management in advanced power microelectronics is aim of DARPA NJTT program

ARLINGTON, Va., 10 Nov. 2010. Microelectronics experts at the U.S. Defense Advanced Research Projects Agency (DARPA) in Arlington, Va., are asking industry for ideas on how to provide electronics thermal management for modern microelectronics -- particularly gallium nitride power amplifiers -- for which traditional conduction, spreading, and convection cooling techniques are not effective. The DARPA Microsystems Technology Office (MTO) issued a broad agency announcement (DARPA-BAA-11-09) Tuesday for the Near Junction Thermal Transport (NJTT) electronics cooling program for advanced thermal management in high-power microelectronics.

Nov 10th, 2010
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ARLINGTON, Va., 10 Nov. 2010. Microelectronics experts at the U.S. Defense Advanced Research Projects Agency (DARPA) in Arlington, Va., are asking industry for ideas on how to provide electronics thermal management for modern microelectronics -- particularly gallium nitride power amplifiers -- for which traditional conduction cooling, heat spreading, and convection cooling techniques are not effective.

The DARPA Microsystems Technology Office (MTO) issued a broad agency announcement (DARPA-BAA-11-09) Tuesday for the Near Junction Thermal Transport (NJTT)electronics cooling program for advanced thermal management in high-power microelectronics. The NJTT program aims at crafting effective near-junction thermal management in high power semiconductors by improving thermal transport in semiconductor structures like wide-band-gap gallium nitride (GaN) power amplifiers.

DARPA is asking microelectronics companies to define and demonstrate thermal management approaches able to facilitate operation of GaN power amplifiers and similar components, which are small and difficult to cool. Existing ideas for improving thermal transport near the GaN power amplifier gates and through to the backside of the device's substrate include active liquid cooling into the near-junction region; using a substrate with very high thermal conductivity; introducing layers providing anisotrop overlayers; and using cryogenic fingers.

In most modern computers, radios, radar modules, and other electronics systems the electronic device is the warmest element in the system, and waste heat is removed by conduction, spreading, and convection to an appropriate working fluid, such as air, water, or a refrigerant, DARPA officials explain.

Yet many military high-power electronic and photonic components can be as large as the resistance of the remaining elements of the system combined, and spreaders, heatsinks, or coldplates do not directly access the active region, and cannot materially affect the device junction temperature.

Consequently, the DARPA NJTT program focuses on near-junction thermal transport in high power electronic and photonic components for which the heat flux in the microscopic active region can be as high as 0.5 kilowatts per square millimeter, which can experience hot spots that can exceed 50 percent of the overall junction-to-ambient temperature rise.

The performance of many military systems depend on the operating power of the device, and generally operate at the at the highest power that creates a tolerable failure rate, DARPA officials explain. Improvements in NJTT that result in substantially lower near junction thermal resistances, therefore, could improve the capabilities of many aerospace and defense systems. as well as help reduce the size and weight of the thermal management system.

For companies interested in competing for the NJTT program, DARPA strongly encourages submitting proposal abstracts before submitting formal proposals. Send abstracts to DARPA no later than 14 Dec. 2010. Full proposals must be submitted to DARPA no later than 24 Feb. 2011.

Send questions or concerns by e-mail to the DARPA NJTT program manager, Dr. Avram Bar-Cohen, by e-mail at DARPA-BAA-11-09@darpa.mil. Also contact Bar-Cohen by phone at 703-351-8361, by fax at 703-807-4950, or by post at DARPA/MTO, ATTN: DARPA-BAA-11-09, 3701 North Fairfax Dr., Arlington, VA 22203-1714.

More information is online at http://www.fbodaily.com/archive/2010/11-November/11-Nov-2010/FBO-02324700.htm.

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