Holy Grail of intrachip microcooling 1000 watts per square centimeter achieved

Researchers have developed a new type of cooling system for high-performance radars and supercomputers that circulates a liquid coolant directly into electronic chips through an intricate series of tiny microchannels.

Above – A new electronics-cooling technique relies on microchannels, just a few microns wide, embedded within the chip itself. The device was built at Purdue University’s Birck Nanotechnology Center. (Purdue University photo/ Kevin P. Drummond)

Conventional chip-cooling methods use finned metal plates called heat sinks, which are attached to computer chips to dissipate heat. Such attachment methods, however, do not remove heat efficiently enough for an emerging class of high-performance electronics, said Suresh V. Garimella, who is principal investigator for the project and the Goodson Distinguished Professor of Mechanical Engineering at Purdue University.

New advanced cooling technologies will be needed for high-performance electronics that contain three-dimensional stacks of processing chips instead of a single, flat-profile chip. Too much heat hinders the performance of electronic chips or damages the tiny circuitry, especially in small “hot spots.”

“You can pack only so much computing power into a single chip, so stacking chips on top of each other is one way of increasing performance,” said Justin A. Weibel, a research associate professor in Purdue’s School of Mechanical Engineering, and co-investigator on the project. “This presents a cooling challenge because if you have layers of many chips, normally each one of these would have its own system attached on top of it to draw out heat. As soon as you have even two chips stacked on top of each other the bottom one has to operate with significantly less power because it can’t be cooled directly.”

The solution is to create a cooling system that is embedded within the stack of chips.

The work has been funded with a four-year grant issued in 2013 totaling around $2 million from the U.S. Defense Advanced Research Projects Agency (DARPA). New findings are detailed in a paper appearing on Oct. 12 in the International Journal of Heat and Mass Transfer.

“I think for the first time we have shown a proof of concept for embedded cooling for Department of Defense and potential commercial applications,” Garimella said. “This transformative approach has great promise for use in radar electronics, as well as in high-performance supercomputers. In this paper, we have demonstrated the technology and the unprecedented performance it provides.”

A fundamental requirement stipulated by DARPA is the ability to handle chips generating a kilowatt of heat per square centimeter, more than 10 times greater than in conventional high-performance computers.

“This number of 1,000 watts per square centimeter is sort of a Holy Grail of microcooling, and we’ve demonstrated this capability in a functioning system with an electrically insulated liquid,” Garimella said.