IBM gives chips a cooling rinse
Researchers develop a system that squirts water over the surface of a processor to cool it--which could promise benefits for server farms.
Researchers at IBM's Zurich labs have developed a "chip cap" filled with a network of channels that can help capture the heat generated by microprocessors and other semiconductors and transport it somewhere else. The design of the hierarchical channels was inspired by similar branching systems found in nature, said IBM, which disclosed details about the project at the Power and Cooling for Data Centres Summit taking place in London this week.
So far, the researchers have demonstrated how the cap can help spread thermal grease more evenly. Thermal grease is a particle-filled substance that conducts heat from the chip to another component, called a heat sink. The idea is to make the layer of grease as thin as possible.
But the team also plans to experiment with ways of squirting water through the channels, using a technique called "direct jet impingement." In this system, the squirted water would be prevented from touching the electronics by the channels and be sucked out quickly. Some server chips have included liquid-filled pipes placed near microprocessors to cool off chips.
In initial laboratory tests of the water system, the Zurich team has demonstrated cooling power densities of up to 370 watts per square centimeter. Conventional air cooling technologies are effective on 75-watt surfaces.
Chips generate a lot of heat, and even though semiconductor makers are developing new transistors and other technologies to curb it, temperatures will continue to climb. Every two years, manufacturers increase the number of transistors they can put into chips (and shrink them) through the magic of Moore's Law. Moreover, smaller transistors increase the energy density of the surface of chips.
Hot chips can melt computers, as well as limit the number of servers that can be squeezed into rack or computer room. That increases real estate costs for big server farms. Heat also forces computer owners to invest heavily in energy-sucking air conditioning systems.
IBM estimates that some chips may have energy densities equivalent to the surface of the sun, when left uncooled. That's 6,000 degrees Celsius.