Silicon heat pipes for cooling electronics

The increasing power density of integrated circuits (ICs) is creating the need for improvements in systems for transferring heat away from the chip. In earlier investigations, diamond films were used to conduct heat from ICs and spread the energy across a heat sink. The authors` investigation has indicated that a 635 {mu}m (25 mil) thick silicon substrate with embedded heat pipes could perform this task better than a diamond film. From their study, it appears that the development of a heat-pipe heat-spreading system is both technically and commercially feasible. The major challenge for this heat-spreading system is to develop an effective wick structure to transport liquid to the heated area beneath the chip. This paper discusses the crucial design parameters for this heat-pipe system, such as the required wick properties, the material compatibility issues, and the thermal characteristics of the system. The paper also provides results from some recent experimental activities at Sandia to develop these heat-pipe heat spreader systems.