Micro-channel/Low Profile Heat Spreader

An innovative heat spreader concept for T/R thermal management is developed in this proposal. The proposed heat spreader has a higher effective thermal conductivity than that of copper, approximately 7 ppm/oC of temperature expansion coefficient (TEC), which is appropriate for brazing or soldering on electronics. The proposed heat spreader uses a refrigerant inside the spreader to transport the heat, giving uniform temperature distribution. Also, the liquid refrigerant is pulled by a capillary force of the porous metal located at the inlet of the evaporation chamber. The evaporated refrigerant moves through the fabricated micro-channel, condenses inside the micro-channel, and then returns to the evaporator. Using two phase heat transfer, the temperature inside the micro-channel is maintained constant, and this mechanism effectively spreads heat, by increasing the surface area. Because of the use of porous metal for returning liquid, this heat spreader is orientation insensitive.