Point cooling advances for hot ICs
By Ron Wilson, Executive Editor -- EDN, March 5, 2009
Engineers have for years been suggesting using thermoelectric films to cool hot ICs because the films develop a temperature difference between their surfaces when you apply a voltage across them. The problems of getting the film next to the IC, establishing a good thermal connection, and packaging the whole thing in a way that allows the heat to escape have often defeated the undertaking, however. Also, in SOCs (systems on chips) and advanced microprocessors, heat often concentrates in small local areas of the die, so that uniformly cooling the die may be ineffective.
Now, researchers from Intel, Nextreme Thermal Solutions, and RTI International have announced a successful experiment in spot cooling using a bismuth-tellurium-antimony-selenium film. The researchers developed the superlattice film using nanoscale layers of the materials. Attaching the film to the backside of a die, apparently directly under a hot spot in the circuitry, the team was able to then package the assembly in a way that conducted the heat from the film to a conventional heat spreader on top of the package.
The completed assembly was able to cool a 1300W/cm² hot spot by as much as 15°C. The team claims that this experiment is the first successful demonstration of a viable chip-scale-refrigeration technology.
