Great potential: Water Cooling as part of Microchips

The idea of liquid cooling with fine channels, which sit directly on the chip and thus enable more efficient cooling than conventional solutions, is by no means new. Corresponding research reports Date back to 2005. But now the cooling should move even closer to the silicon, more precisely: into the silicon.

In their report "Co-designing electronics with microfluidics for more sustainable cooling", researchers from the POWERlab at the Institute of Electrical Engineering, École Polytechnique Fédérale de Lausanne (EPFL), describe the new approach. As a graphic illustrates, tiny channels for the liquid coolant (here water) are already worked into the silicon during the production of the chip. The researchers call the system "monolithically integrated manifold microchannel" (mMMC). The above circuits are cooled by heat exchange. The initially cold water is passed through a manifold (manifold) which feeds it into the micro-channels located directly under the semiconductor made of a layer of gallium nitride (GaN). The heat generated by the circuits is transferred to the water via copper contacts, which immediately seal the channels, and discharged above them.

 

Water Cooling Microchips

For the demonstration, a rectifier was produced in which heat flows of more than 1.7 kilowatts per square centimetre with a pump output of only 0.57 W/cm² could be cooled, according to the researchers.

However, the technology is still a long way from being launched on the market. Among other things, the stability of the thin GaN layer had to be checked over a longer period of time. In addition, an adhesive was used to connect the microchannels to the water supply from the carrier board, said adhesive only surviving temperatures of up to 120°C. However, temperatures of up to 250°C are common in the production of final products. In addition, alternatives to water as a coolant had to be sought.

 

The technology should offer huge potential when used in data centers: While these previously required 30 percent additional energy for cooling, this share could potentially fall to below 0.01 percent, according to the researchers. According to Spektrum, according to a calculation, the data centers in the USA alone would need about 24 terawatt hours of energy per year and 100 billion litres of water for cooling. Accordingly, research into new, resource-conserving solutions is of relevance.