The New Generation of Cool Computer Chips

One of the biggest problems with computers is the residual heat, which requires large, often noisy cooling systems, but can also physically damage internal components, and as portable devices become smaller and slimmer, finding a way to cool them down is an important challenge for manufacturers around the world.

As part of their functioning process, chips inside an electronic device give off heat as a byproduct of power consumption when the object is on or being used. To reduce high temperatures, heat sinks - finned devices made of conductive metal such as aluminum or copper - are attached to the back of the chips to pull thermal energy away from the microprocessor and transfer it into the surrounding air. Fans or fluids are sometimes used to improve the cooling process, but they increase the device weight, size, and bulk.

New research suggests that carbon nanotubes may soon be integrated into ever-shrinking cell phones, digital audio players, and personal digital assistants to help ensure the equipment does not overheat, malfunction, or fail.

Using microfin structures made of aligned multiwalled carbon nanotube arrays mounted to the back of silicon chips, researchers from Rensselaer Polytechnic Institute and the University of Oulu in Finland have proven that nanotubes can dissipate chip heat as effectively as copper - the best known, but most costly, material for thermal management applications. And the nanotubes are more flexible, resilient, and 10 times lighter than any other cooling material available.

"As devices continue to decrease in dimension, there is a growing need for miniature on-chip thermal management applications," said Robert Vajtai, a researcher with the Rensselaer Nanotechnology Center and corresponding author on the paper. "When reduced to sub-millimeter sizes, the integrity of materials typically used for cooling structures breaks down. Silicon becomes very brittle and easily shatters, while metallic structures become bendable and weak."

Carbon nanotubes maintain their impressive combination of high strength, low weight, and excellent conductivity, and the carbon nanotube coolers can be manufactured very cost efficiently, and may soon replace currently used metals and alloys.

The results of the experiments "are consistent with the heat dissipated by the best thermal conductors, and demonstrate the possibility of a lightweight, solid-state add-on structure for an on-chip thermal management scheme which works without involving heavy metal block and fan or fluid-flow procedures for heat removal which can greatly increase the weight of electronic devices," Vajtai said.