PORTLAND, Ore.Nanoscale coatings could boost the efficiency with which heat can be removed from semiconductors and other devices, according to an Army Research Laboratory funded study by researchers at the Pacific Northwest National Laboratory (PNNL) and Oregon State University (OSU).
"A 10X improvement in heat transfer coefficient was observed for nanostructured surfaces over a 'bare' aluminum substrate. Further, an approximate 4X improvement in critical heat flux was also measured for these nanostructured surfaces," said the project leader at PNNL, Terry Hendricks. He performed the study with OSU professor Chih-hung Chang.
The nanoscale coating method, dubbed microreactor assisted nanomaterial deposition (MAND), deposited tiny grains of zinc oxide atop bulk aluminum and copper. As a result of the nanostructured coatings, heat was transfered far more efficiently. The researchers claim that their coating techniques will help in the cooling for advanced lasers, radars, and power electronics devices in applications including high performance computers, advanced military avionics, electric vehicles and energy recovery systems.
|Nanoscale coating of zinc oxide on top of a copper plate boost heat transfer coefficient 10-times according to experts at Oregon State University and the Pacific Northwest National Laboratory. (Photo courtesy of Oregon State University)|
The mechanism used by MAND to remove the heat is still being investigated but appears to be cause by higher-density nucleation sites and better capillary pumping action, resulting in an improved heat-transfer surface-area per unit volume.
For forced liquid cooling systems using advanced microchannel architectures, the researchers hypothesize that their work exposes a critical tradeoff between nucleation site density, bubble frequency and bubble diameter that can be optimized for maximun heat dissipation.