Researchers apply cooling for 3D chips with microchannels
Scientists at Purdue University have developed a chip cooling method that works by injecting liquid into channels about ten micrometers wide. The cooling technology could be applied to 3D chips, among other things.
Researchers have been experimenting with integrating microchannels on chips for some time, but the Purdue University team has reduced the width by a factor of ten to 10 to 15 micrometers. In addition, the design has been modified in such a way that the liquid is easier to inject into the channels. In previous experiments, channels as long as 5000 micrometers were etched into the silicon, making it difficult to pump the liquid, but the researchers now use significantly shorter lines, from 250 to 300 micrometers.
The researchers have developed a prototype with a chip surface of 5x5mm. They use the coolant HFE-7100 for a grid of three by three heatsinks with the microchannels. They placed a heating element and sensors on the back of the chip to measure the temperature. Using a heatsink with channels 15 µm wide and 300 µm long, the dissipation was 910W/cm².
At the hottest point of the chip, the liquid reaches its boiling point. “By boiling the liquid, the rate at which heat can be removed significantly increases, compared to simply heating the liquid below its boiling point,” said Purdue student Kevin Drummond, who helped with the study.
The cooling method should, among other things, solve the problem that chip manufacturers resort to stacking chips to improve performance. “Normally each layer has its own system attached to remove heat. Once you’ve stacked even two chips, the bottom one should consume less because it can’t be cooled directly,” said Justin Weibel, professor at Purdue’s School of Mechanical Engineering. .
The research was co-funded by the US government’s Defense Advanced Research Projects Agency. Darpa has a target of 1000W/cm² for cooling for future high performance computing, something the team has almost achieved. The cooling technology could be used for supercomputers and radar electronics.
The researchers describe their findings in a study called A hierarchical manifold microchannel heat sink array for high-heat-flux two-phase cooling of electronics, published in the scientific journal International Journal of Heat and Mass Transfer.