The main goal of this project is to develop a new technique to fabricate the coherent porous silicon (CPS) wick and integrate it into the micro loop heat pipe (micro-LHP). Another goal is to optimize the pore size, pitch, porosity and wick thickness to maximize the heat flux and capillary pressure in the device. Through control of pore size, the flow resistance of the micro-LHP will be defined. Finally, the novel design of the CPS wick will significantly increase the efficiency of micro-LHP while preventing the severe problems such as bubble formation, liquid- vapor interface oscillation, and wick dry out. The micro-LHP is a two phase thermal ground plane device for chip-level, integrated cooling. This system draws significant heat flux from electronics when the operating fluid changes to the vapor phase. The porous wick, a key component of the micro-LHP, is located between evaporator and reservoir and it serves as the engine which achieves continuous fluid circulation. It feeds coolant to the evaporator surface, determines the capillary pumping capability of the overall micro-LHP system and serves as thermal barrier between the coolant channels and evaporator chamber. The traditional sponge-like porous wicks have a randomly distributed pore size and irregular flow path. On the contrary, three- dimensional porous structures made via ion- track etching, photolithography, and replica molding have complex fabrication process and restrictions on the device design.
Project end date: 01/28/14