This book presents a comprehensive research work on the vapor chamber heat spreader (VCHS). Base on the experimental data, the study try to date regarding parametric effects of Vapor Chamber Heat Spreader to the electronic cooling application. A series of prototype vapor chamber heat spreaders with different working fluid filling ratios have been built and tested for its thermal performance. To investigate the influence of the gravity on the VCHS performance, tests were conducted under 0, 45, 90, 135,and 180 five different tilt angles. The results also shown that they have almost the same performance, and just little difference for the case of vertical install. The spreading resistance is the dominating factor in determining the overall thermal resistance of a vapor chamber. VCHS can enhance the system performance both in air and water cooling tests.