Microfabricated thin silicon vapor chambers for low profile thermal management
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Portable electronics, such as smartphones, tablets, and ultrabooks are innovating rapidly. They are becoming as powerful as desktop computers, and incorporating multiple functionalities enabled through three-dimensional electronics, or 2.5-dimensional interposer based packaging approaches. To keep these compact electronic systems operating efficiently and reliably, thermal management becomes a challenging problem. A proposed solution is to develop miniature thermal management devices suitable for integration into small form factor packages, incorporating silicon interposers, or three-dimensional packaging. Vapor chamber is a technology that utilizes the latent heat of liquid/vapor phase change of a working liquid for heat removal, and passive capillary action to return the condensed liquid to the heat source. The main goal of this study is to develop a submillimeter thick vapor chamber that can be integrated into silicon interposer, and performs better than solid silicon heat spreader of the same thickness. This study includes the following aspects: 1) investigation of capillary pressure of different homogeneous wicks using Surface Evolver, fabrication process of 720 ±10 µm thick vapor chambers with patterned bi-porous monolayer copper powder wick structures; 2) development of a charging station that evacuates and charges a vapor chamber at a rate of 10 µl/min; 3) thermal characterization experiments for the fabricated vapor chambers to evaluate their performance; 4) validation of the experimental results by a three-dimensional heat conduction model, coupled with a thermal resistance network for the vapor chamber.