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MICROFLUIDIC passages cut directly into microchips could provide better cooling without the need for heatsinks or fans.
Researchers from the Georgia Institute of Technology experimented on a 28nm FPGA device made by Altera. They removed the heat sink and heat-spreading materials, then etched cooling passages into the silicon, incorporating silicon cylinders approximately 100 microns in diameter to improve heat transmission into the liquid.
A silicon layer was then placed over the flow passages, and ports were attached for the connection of water tubes. They then ran de-ionised water through the passages, just a few hundred microns away from the transistors.
With a water inlet temperature of approximately 20 degrees Celsius and an inlet flow rate of 147 milliliters per minute, the liquid-cooled FPGA operated at a temperature of less than 24 degrees Celsius, compared to an air-cooled device that operated at 60 degrees Celsius.
With heat being one of the major barriers to building high-performance systems that are both more compact and energy efficient, the researchers believe that reliably integrating microfluidic cooling directly on the silicon will be a disruptive technology for a new generation of electronics.
The new technologies could allow development of denser and more powerful integrated electronic systems that would no longer require heat sinks or cooling fans on top of the integrated circuits.
In addition to more processing power, the lower temperatures can mean longer device life and less current leakage.
While liquid cooling is already used in many applications, conventional uses of the technology involves using cold plates externally attached to fully packaged silicon chips. This adds thermal resistance.
As the first example of liquid cooling integrated directly on an operating high-performance CMOS chip, the new liquid cooling technology would be able to more quickly and efficiently remove heat from the transistors within the chip. It would also eliminate hotspots, and allow more compact packaging.
According to the researchers, they tested the techique on FPGAs due to the common use of the chips in many market segments, including defense. This is also partly because the cooling research was funded by DARPA’s Microsystems Technology Office.
However, the same technology could also be used to cool CPUs, GPUs and other devices such as power amplifiers.