Posted: May 7, 2008

University of Colorado wins $1.5 million contract to aid In cooling of electronic devices

(Nanowerk News) A University of Colorado at Boulder research center has won a $1.5 million contract with its long-time partner Lockheed Martin Corp. to demonstrate new micro- and nanotechnologies that promise to significantly improve thermal management in electronic devices, one of the critical constraints on today's consumer and military electronic systems.
The initial 18-month contract from the Defense Advanced Research Projects Agency, or DARPA, managed by Thomas Kenny of the Microsystems Technology Office, is for the first phase of an effort to demonstrate the feasibility of replacing the copper heat pipe that is common in electronics and space systems today with a thermal ground plane -- a common, underlying component of printed circuit boards -- made of flexible polymer materials.
The total value of the effort, if all phases of the development program are completed, could be up to $3.95 million over four years.
The concept developed by Assistant Professor Ronggui Yang at CU-Boulder has vastly superior ability to remove the heat generated in computers and cell phones, as well as in new generations of energy systems such as flexible solar cells and batteries where heat removal requirements have limited further improvements, according to Professor Y.C. Lee of mechanical engineering, who directs the DARPA Focus Center on Nanoscale Science and Technology for Integrated Micro/Nano-Electromechanical Transducers, or iMINT.
"Cooling is the No. 1 problem in electronics, and this represents a total paradigm shift," Lee said. "Flexible thermal ground planes have 100 times better thermal conductivity than copper and will enable a new generation of high-performance, integrated microelectronic, photonic or microwave systems operating at high power density without constraints resulting from complex thermal management solutions."
The research team plans to fabricate a thermal ground plane that is only 1 millimeter thick, which is comparable to a credit card but with an area as large as a laptop computer. The thermal ground plane can be used as a stand-alone component or integrated in a printed circuit board connecting chips and other components, according to Yang.
A smaller thermal ground plane could be fabricated in the same way for use in a device such as a cell phone. Or, since the polymer material is flexible, it could be folded back and forth in a stack configuration although this would be a greater challenge, Yang said.
The polymer ground plane will encase a nanoscale wicking structure in which distilled water is alternately vaporized and condensed, as in a more conventional heat pipe, to remove heat from a laser diode, a microprocessor or a transceiver. The polymer will be coated with alumina through atomic layer deposition to provide a vapor barrier, which will maintain the water for long-time operation.
The technological innovation came about in a "perfect storm" of research interests coming together at CU-Boulder. "We have every piece of the puzzle here," Lee said.
Three CU faculty members who joined the university in 2006 established the core concept for the novel thermal ground plane: Yang, who brought expertise in nanostructured materials and heat transfer; Professor and Chancellor G.P. "Bud" Peterson, a world expert in heat pipes; and Research Assistant Professor Chen Li, who contributed to the heat transfer modeling and design.
Their concept matched well with the technologies already developed by CU professors Steven George, who patented atomic layer deposition coating technology; Victor Bright, a micro- and nanotechnology expert with years of experience working with DARPA; and Lee, an expert in micro- and nanoscale manufacturing and packaging technologies. Except for George, who is based in chemistry and chemical engineering, all of the other team members are faculty in mechanical engineering.
Lockheed Martin also has been a long-time partner in the research, having provided the first seed grant to improve atomic layer deposition for hydrophobic coating in 2002, a technology that is essential to the proposed thermal ground plane. "Lockheed Martin considers it a unique opportunity to benefit from CU researchers and incorporate their innovative thermal management solutions into future aerospace systems," said Suraj Rawal, senior manager for research in advanced materials and structures at Lockheed Martin Space Systems.
iMINT, which was established in fall 2006 with a DARPA grant managed by Dennis Polla, attracted nearly $1.5 million in government and industrial funding in its first year of operation. With the new contract, the center's research activities will be expanded to more than $2.5 million per year.
"This new thermal ground plane contract is a good example of how fundamental research conducted at the DARPA iMINT center can stimulate new system-level research for real-world applications and how industry sponsors such as Lockheed Martin can benefit from the expanded activities," Lee said.
Additional industry sponsors are being sought to participate in the thermal ground plane development as well as other engineering research projects.
Source: University of Colorado at Boulder
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