Researchers take leaf from nature to cool chips

Today's more powerful processors can release more heat per square centimeter than a typical hotplate. To deal with that, the new approach addresses the connection point between the hot chip and the various cooling components that draw the heat away, including heat sinks. Typically special particle-filled pastes are applied to this interface to guarantee that chips can expand and contract. The paste is kept as thin as possible in order to transport heat from chip to the cooling components efficiently. Yet, squeezing the paste too thinly between the cooling components and chip can damage or crack the chip. Using sophisticated micro-technology, the IBM researchers developed a chip cap with a network of tree-like branched channels on its surface. The pattern is designed so that when pressure is applied, the paste spreads much more evenly and the pressure remains uniform across the chip. This allows the right uniformity, but with nearly two times less pressure and a 10 times better heat transport. IBM researchers in Zurich borrowed the design from biology. Called systems of hierarchical channels, similar designs can be found in tree leaves, roots, and the human circulatory system. They can serve very large volumes with little energy. "Cooling is a holistic challenge from the individual transistor to the datacenter. Powerful techniques, brought as close as possible to the chip right where the cooling is needed, will be crucial for tackling the power and cooling issues," said Bruno Michel, manager of the Advanced Thermal Packaging research group at IBM's Zurich lab. "Electronic products are capable of amazing things, largely because of the more powerful chips at their heart. We want to help electronics makers keep the innovations coming. Our chip-cooling technology is just one tool at our disposal to help them do that."