Limitations in advancements in electronic technology and further development of new technology are due to inadequate thermal management. As Moore's Law continues to drive semiconductor technology, the capabilities of conventional thermal management methods are falling behind the constantly changing and increasing needs of the electronic industry. Roadmap projections for the high-performance chip category suggest that the maximum chip power dissipation will exceed 500 W, and the chip heat flux will exceed 150 W/cm2 within the next few years. Research currently focuses on two-phase cooling techniques due to their potential to meet the thermal management needs of leading-edge electronic technology. Potential solutions currently being studied include spray cooling, immersion cooling, micro heat pipes, and microgap cooler. Unlike many current thermal management devices, microgap cooler eliminate the high and problematic thermal contact resistance, by allowing direct cooling of an electronic component by the flow of dielectric liquid across the back surface of the chip or substrate. The heat dissipation capability of such microgap coolers is further enhanced by two-phase flow that develops in the microgap channel, producing higher heat transfer coefficients than achievable by single-phase forced convection with that same fluid. In addition, due to the potential utilization of the intrinsic gaps between chips and within the packaging enclosures in both 2.5D (using interposers) and 3D configurations, microgap coolers provide a promising solution to the challenging problem of high-density heat removal. Despite the many advantages of two-phase microgap coolers, much is still not understood about the physics that governs this thermal management technique and the phenomena that limit its performance.