Thermal Management Technologies for Embedded Cooling Applications

Embedded computing systems used in many applications are trending toward higher heat fluxes and powers. As a result, the thermal resistance between the electronics and the heat sink must be reduced to keep the electronics temperature to acceptable levels. The thermal resistance path includes the thermal interface material, conduction card, wedge lock interface, and card cage wall. In addition, a vapor chamber may be included to transform high heat fluxes to a lower flux that the other components can handle. This paper outlines three passive thermal improvements which are easily integrated into systems: (1) A CTE matched, high-heat-flux vapor chamber that replaces an existing CuMo heat spreader resulting in a temperature reduction of 43°C at a heat flux of 520 W/cm
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, (2) an improved wedge lock with two directions of expansion, cutting thermal resistance by one-third, by increasing the surface area for heat transfer and maximizing contact pressure, and (3) an improved thermal design for a composite box that integrates heat pipes to overcome the very low thermal conductivity of composites, typically 1 W/m K. When combined with heat pipes integrated into the conduction cards, they can provide a 3-4x increase in dissipated power.