The technique, called "high thermal conductivity interface technology," allows a twofold improvement in heat removal over current methods. This paves the way for continued development of creative electronic products through the use of more powerful chips without complex and costly systems simply to cool them. 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 such that when pressure is applied, the paste spreads much more evenly and the pressure remains uniform across the chip. This allows the right uniformity to be obtained with nearly two times less pressure, and a ten times better heat transport through the interface.
Looking beyond the limits of air-cooling systems, Zurich researchers are taking their concept of branched channel design even further and are developing a novel and promising approach for water-cooling. Called direct jet impingement, it squirts water onto the back of the chip and sucks it off again in a perfectly closed system using an array of up to 50,000 tiny nozzles and a complicated tree-like branched return architecture.
By developing a perfectly closed system, there is also no fear of coolant getting into the electronics on the chips. What's more, the IBM team was able to enhance the cooling capabilities of the system by devising ways to apply it directly to the back of the chip and thereby avoiding the resistive thermal interfaces in between the cooling system and the silicon.
First lab results are impressive. The team has demonstrated cooling power densities of up to 370 Watts per square centimeter with water as coolant. This is more than six times beyond the current limits of air-cooling techniques at about 75 Watts per square centimeter. Yet, the system uses much less energy for pumping than other cooling systems do. This next step would provide a further doubling of cooling performance.