SUBJECT: M.S. Thesis Presentation
BY: Jiaxing Liang
TIME: Tuesday, May 2, 2017, 1:30 p.m.
PLACE: Love Building, 210
TITLE: Microfabricated Vapor Chambers for Interposer Integrated Cooling
COMMITTEE: Yogendra Joshi, Co-Chair (ME)
Muhannad S Bakir, Co-Chair (ECE)
Suresh K. Sitaraman (ME)


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.