To cope with the growing power dissipation level of the electronic devices, a phase change liquid jet and spray impingement cooling technique has been developed. The technique has been applied to cool a 1cm × 1cm heat source mimicking an IGBT in an open and closed loop system. In a front side (chip level) cooling approach DI water impinges on a 12.5μm thin dielectric coating layer covering the heat source. A 119-200μm micro-jet array and a 610μm orifice atomizer are used. A high heat flux of 750W/cm2 is reported when the heat source (device) temperature reaches ~175°C. Non-uniformity of the heat source temperature and methods to reduce it are investigated. By controlling the closed loop system pressure to a sub-atmospheric condition and initiating early boiling, the heat source temperature has been reduced up to 60°C, compared to the 1 atmospheric condition, at ~400W/cm2 flux level. A comparative study of the front and backside cooling approaches is presented.