Researchers at the University of California, Berkeley and the University of California, San Diego have developed a novel evaporator structure that can be integrated directly into electronics to cool chips with micro-sized components.
“The idea behind this project is to use liquid, in this case de-ionized water, to absorb the heat produced by any kind of device, then evaporate the liquid to dissipate heat,” Ph.D. student Lilla Safford Smith explained. Stafford Smith, who is part of the research group of Albert Pisano, dean of the Jacobs School of Engineering at UC San Diego and a professor of mechanical and electrical engineering, presented her work on the evaporator device at the PowerMEMS 2013 conference in London and at the Jacobs School’s Research Expo on the UC San Diego campus in April.
Incorporated into a chip using traditional manufacturing techniques, the evaporator is made of silicon with structures evocative of stone pillars that measure 25 microns high, 10 microns thick and 10 microns across. Each evaporator is installed over a tiny—five millimeters by five millimeters—heater that brings the water on the chip to just above its boiling point of 102 to 110 degrees Celsius, or 215 to 230 degrees Fahrenheit. When exposed to such heat, the water changes from a liquid to a gas.
“The evaporator’s essential function is to ensure that [the] thin film of de-ionized water used to cool the chip remains the right size. The thinner the film of liquid, the more it evaporates, but if it is too thin, it can’t evaporate and becomes ineffective,” explains a UCSD press release.
The researchers will take the project to the next step by incorporating the evaporator into a system with a wick as a pump that will allow the water to circulate to and from the hottest areas on the chip, making a completely passive thermal management device.