Researchers unveil microfluidics heat sink

By Gina Roos, editor-in-chief

Aimed at solving the heat challenge in the next generation of power electronics and systems in a package, research and innovation hub imec recently revealed a miniature silicon-based microchannel heat sink for high-performance chip cooling. Enabling high heat flux dissipation, the microfluidics heat sink is assembled to the chip and achieves a low total thermal resistance of 0.34 K/W to 0.28 K/W at less than 2-W pump power.

To build the chip cooler, researchers used small, parallel, high-aspect-ratio silicon microchannels that measure 32 µm wide and more than 260 µm deep, which increased the convective heat transfer surface area and the heat transfer coefficient. As a result, it enabled high heat flux removal and the heat dissipation of more than 600 W/cm² while keeping the component temperature below 100°C.

Imec said that by using silicon (Si) technology, which is a “relatively good heat conductor,” to fabricate the heat sink’s microchannels, the final devices are higher-quality and lower-cost.

Major challenges in the electronics industry — shrinking IC chips and increasing power density — has resulted in cooling challenges, which have an impact on device performance and reliability. Thanks to the higher thermal conductivity and specific heat capacity of liquid, it is more effective in heat removal compared to air, said imec.

“The key attribute of silicon is that it can realize high-aspect-ratio microstructures at low cost by leveraging massively parallel production processes and is directly integrable in the semiconductor infrastructure,” said imec. “In the current version, the Si-based microchannel heat sinks are fabricated separately and then interfaced to the back side of a heat-dissipating chip.”

Researchers created a Cu/Sn-Au interface to achieve a very low thermal contact resistance between both parts. In addition, the micro-cooler can be accurately tailored to external system constraints such as space and liquid supply.

“Imec’s microfluidic heat sink realized on a Si platform is a best-in-class technology demonstrating the lowest thermal resistance allowing a power dissipation of over 600 W/cm² in a very small form factor,” said Philippe Soussan, principal member of the technical staff, in a press release . “It allows for an increase in heat flux by two orders of magnitude compared to classical metal heat sinks. Imec is working toward developing a next generation of this chip-cooling solution, directly integrating the heat sinks and the IC at wafer scale, aiming at an additional cost of $1.”