Engineered Nanostructures for High Thermal Conductivity Substrates
In the DARPA Thermal Ground Plane (TGP) program[1],we are developing a new thermal technology that will enable a monumental thermal technological leap to an entirely new class of electronics, particularly electronics for use in high-tech military systems. The proposed TGP is a planar, thermal expansion matched heat spreader that is capable of moving heat from multiple chips to a remote thermal sink. DARPA's final goals require the TGP to have an effective conductivity of 20,000 W/mK, operate at 20g, with minimal fluid loss of less than 0.1%/year and in a large ultra-thin planar package of 10cmx20cm, no thicker than 1mm. The proposed TGP is based on a heat pipe architecture[2], whereby the enhanced transport of heat is made possible by applying nanoengineered surfaces to the evaporator, wick, and condenser surfaces. Ultra-low thermal resistances are engineered using superhydrophilic and superhydrophobic nanostructures on the interior surfaces of the TGP envelope. The final TGP design will be easily integrated into existing printed circuit board manufacturing technology. In this paper, we present the transport design, fabrication and packaging techniques, and finally a novel fluorescence imaging technique to visualize the capillary flow in these nanostructured wicks. ; United States. Defense Advanced Research Projects Agency (SSC SD Contract No. N66001-08-C-2008)
