{"46274":{"#nid":"46274","#data":{"type":"news","title":"Heat-Transfer Material Could Allow More Powerful Radar Electronics","body":[{"value":"\u003Cp\u003EOpen any computer and you\u0027re sure to see at least one massive cooling device, complete with metal fins and a noisy fan. Today\u0027s high-power processing chips generate lots of heat -- and those chips can fry quickly without some serious cooling.\u003C\/p\u003E\n\u003Cp\u003EResearchers at the Georgia Tech Research Institute (GTRI) are developing a novel material for transferring heat away from ultra-high-power defense electronics. The exotic material, a composite of diamond and copper, is one of the materials under development as part of a new concept called a \u0022Thermal Ground Plane\u0022 that aims to remove heat up to 100 times more effectively than present thermal-conducting schemes.\n\u003C\/p\u003E\n\u003Cp\u003ESuch a performance leap could be vital to cooling next-generation radars, said Jason Nadler, a GTRI research engineer. Nadler is investigating ways to bring new materials and techniques to bear on the problem.\n\u003C\/p\u003E\n\u003Cp\u003E\u0022Many areas of electronics are running up against the same issue: you just can\u0027t move the heat away fast enough to let the devices be reliable,\u0022 Nadler said. \u0022As we rely increasingly on very high-power devices, the methods of getting heat away from them have to become more efficient.\u0022\n\u003C\/p\u003E\n\u003Cp\u003EGeorgia Tech is working with the Raytheon Co. on a project that seeks to raise thermal conductivity capabilities to 20,000 watts per meter Kelvin (a measure of thermal-conductivity efficiency). That\u0027s a tall order, considering that the current conductivity champion, for radar applications, is a copper material with performance of approximately 200 to 300 watts per meter Kelvin.\n\u003C\/p\u003E\n\u003Cp\u003EThe three-phase, four-year project is sponsored by the Microsystems Technology Office of the Defense Advanced Research Projects Agency (DARPA).\n\u003C\/p\u003E\n\u003Cp\u003EThis improved cooling capability could benefit future high-power transmit-receive (T\/R) module packages. Because of their higher power, those transmit-receive modules will also have higher cooling needs that may require a Thermal Ground Plane -- a sort of heat-dissipating sandwich about one millimeter thick that would be part of the T\/R module\u0027s packaging.\n\u003C\/p\u003E\n\u003Cp\u003E\u0022A Thermal Ground Plane is basically a materials system,\u0022 Nadler explained. \u0022The most thermally conductive natural material, pure diamond, has a conductivity of about 2,000 watts per meter Kelvin. We\u0027re aiming for 20,000, and to do that we have to look at the problem from a materials systems standpoint.\u0022\n\u003C\/p\u003E\n\u003Cp\u003ENadler\u0027s material is one of those under development to serve as the heart of the Thermal Ground Plane. The conductivity of that material would be improved with the addition of a liquid coolant able to carry heat away from the T\/R module devices in the same way that sweat cools a body. A metal heat sink would help the liquid coolant dissipate the heat by condensing the vapor back to a fluid.\n\u003C\/p\u003E\n\u003Cp\u003EUsing a liquid coolant takes advantage of phase changes -- the conversion of matter between liquid and vapor states. The diamond-copper material would conduct heat to the liquid coolant and optimize cooling through wicking and evaporation. Then, the heat would be rejected as the vapor is re-condensed to a liquid on the side attached to the metal heat sink.\n\u003C\/p\u003E\n\u003Cp\u003E\u0022The trick is to use evaporation, condensation and intrinsic thermal conductivity together, in series, in a continuous system,\u0022 Nadler said. \u0022The whole device is a closed loop.\u0022\n\u003C\/p\u003E\n\u003Cp\u003EChallenges remain, however, including some specific materials issues. To form the desired materials, diamond and copper must be integrated into a porous structure that can best transfer heat and facilitate efficient evaporation.\n\u003C\/p\u003E\n\u003Cp\u003EBut diamond and copper don\u0027t bond well, due in part to their different coefficients of thermal expansion and chemical incompatibility. Diamond doesn\u0027t expand much when heated, while copper expands moderately. That difference leads to a thermal-expansion mismatch, which can fracture the interface between the two materials when they\u0027re heated.\n\u003C\/p\u003E\n\u003Cp\u003EIn addition, the porous internal structure of the diamond-copper material must have exactly the right size and shape to maximize its own intrinsic heat conductivity. Yet its internal structure must also be designed in ways that can help draw the liquid coolant toward the heat source to facilitate evaporation.\n\u003C\/p\u003E\n\u003Cp\u003ENadler explained that liquid coolant flow can be maximized by fine tuning such mechanisms as the capillarity of the diamond-copper material. Capillarity refers to a given structure\u0027s ability to draw in a substance, especially a liquid, the way a sponge absorbs water or a medical technician pulls a drop of blood up into a narrow glass tube.\n\u003C\/p\u003E\n\u003Cp\u003ETo be effective, the size of a capillary structure must be precisely controlled; if it\u0027s too large or too small, the wicking phenomenon won\u0027t occur. The GTRI team must size the diamond-copper material\u0027s internal structure to maximize capillarity.\n\u003C\/p\u003E\n\u003Cp\u003E\u0022We\u0027re finding ways to change the cellular structure of the diamond-copper material at the nanoscale and the microscale,\u0022 Nadler said. \u0022We\u0027re doing this by making complex open-celled structures -- basically tiny foams with exactly the right properties.\u0022\n\u003C\/p\u003E\n\u003Cp\u003E\u003Cstrong\u003EResearch News \u0026amp; Publications Office\u003Cbr \/\u003E\nGeorgia Institute of Technology\u003Cbr \/\u003E\n75 Fifth Street, N.W., Suite 100\u003Cbr \/\u003E\nAtlanta, Georgia 30308 USA\u003C\/strong\u003E\n\u003C\/p\u003E\n\u003Cp\u003E\u003Cstrong\u003EMedia Relations Contacts\u003C\/strong\u003E: Kirk Englehardt (404-407-7280); E-mail: (\u003Ca href=\u0022mailto:kirkeng@gatech.edu\u0022\u003Ekirkeng@gatech.edu\u003C\/a\u003E) or John Toon (404-894-6986); E-mail: (\u003Ca href=\u0022mailto:jtoon@gatech.edu\u0022\u003Ejtoon@gatech.edu\u003C\/a\u003E) or Abby Vogel (404-385-3364); E-mail: (\u003Ca href=\u0022mailto:avogel@gatech.edu\u0022\u003Eavogel@gatech.edu\u003C\/a\u003E).\n\u003C\/p\u003E\n\u003Cp\u003E\u003Cstrong\u003EWriter\u003C\/strong\u003E: Rick Robinson\n\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"Researchers at the Georgia Tech Research Institute (GTRI) are developing a novel material for transferring heat away from ultra-high-power defense electronics. The exotic material is a composite of diamond and copper.","format":"limited_html"}],"field_summary_sentence":[{"value":"A new material based on diamond could improve electronics coolin"}],"uid":"27303","created_gmt":"2009-07-09 00:00:00","changed_gmt":"2016-10-08 03:03:14","author":"John Toon","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2009-07-09T00:00:00-04:00","iso_date":"2009-07-09T00:00:00-04:00","tz":"America\/New_York"},"extras":[],"hg_media":{"46275":{"id":"46275","type":"image","title":"Electronics Cooling","body":null,"created":"1449174375","gmt_created":"2015-12-03 20:26:15","changed":"1475894414","gmt_changed":"2016-10-08 02:40:14","alt":"Electronics Cooling","file":{"fid":"101062","name":"tas56071.jpg","image_path":"\/sites\/default\/files\/images\/tas56071_0.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/tas56071_0.jpg","mime":"image\/jpeg","size":709360,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/tas56071_0.jpg?itok=hTJ3r9WV"}},"46276":{"id":"46276","type":"image","title":"Electronics cooling","body":null,"created":"1449174375","gmt_created":"2015-12-03 20:26:15","changed":"1475894414","gmt_changed":"2016-10-08 02:40:14","alt":"Electronics cooling","file":{"fid":"101063","name":"tfk56072.jpg","image_path":"\/sites\/default\/files\/images\/tfk56072_0.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/tfk56072_0.jpg","mime":"image\/jpeg","size":1180865,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/tfk56072_0.jpg?itok=KFBwuC2C"}},"46277":{"id":"46277","type":"image","title":"Electronics cooling","body":null,"created":"1449174375","gmt_created":"2015-12-03 20:26:15","changed":"1475894414","gmt_changed":"2016-10-08 02:40:14","alt":"Electronics cooling","file":{"fid":"101064","name":"tvt56072.jpg","image_path":"\/sites\/default\/files\/images\/tvt56072_0.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/tvt56072_0.jpg","mime":"image\/jpeg","size":1793066,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/tvt56072_0.jpg?itok=ykJrpoHA"}}},"media_ids":["46275","46276","46277"],"related_links":[{"url":"http:\/\/www.gtri.gatech.edu\/","title":"Georgia Tech Research Institute"}],"groups":[{"id":"1188","name":"Research Horizons"}],"categories":[{"id":"153","name":"Computer Science\/Information Technology and Security"},{"id":"145","name":"Engineering"},{"id":"147","name":"Military Technology"},{"id":"135","name":"Research"}],"keywords":[{"id":"437","name":"cooling"},{"id":"7129","name":"diamond"},{"id":"609","name":"electronics"},{"id":"7128","name":"heat-transfer"},{"id":"2621","name":"radar"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cstrong\u003EJohn Toon\u003C\/strong\u003E\u003Cbr \/\u003EResearch News \u0026amp; Publications Office\u003Cbr \/\u003E\u003Ca href=\u0022http:\/\/www.gatech.edu\/contact\/index.html?id=jt7\u0022\u003EContact John Toon\u003C\/a\u003E\u003Cbr \/\u003E\u003Cstrong\u003E404-894-6986\u003C\/strong\u003E","format":"limited_html"}],"email":["jtoon@gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}