A single flexible coldplate cools multiple devices

Abstract

For high-speed computer systems, the high-power devices such as Central Processor Units (CPUs) and Graphics Processing Units (CPUs) generally must be arranged close together to reduce electrical channel routing distances. In such cases water cooling enables greater device density than that achievable with air cooling. In contrast to typical implementations that utilize a separate coldplate for each high-power device, we use a single flexible coldplate to cool multiple devices. The flexibility allows the single coldplate to adapt to varying device heights and/or tilts. We solder or braze the perimeters of two thin, concave metal sheets to form a coldplate chamber. Cooling fin packs inside the chamber are soldered or brazed to internal chamber walls. Careful control of this metal-to-metal interface is required to minimize voiding and achieve good thermal contact Under the fin packs the external chamber wall contacts the heat generating devices through a thermal interface material (TIM). In the regions between devices, the thin walls of the empty cavity provide mechanical flexibility. This allows for device height variation while maintaining full contact through a thin TIM. Having a single coldplate reduces both cost and potential water leakage at attachment junctions.