A 3D printed cold plate made of pure copper could pave the way for more efficient cooling in data centers, scientists claim.

Researchers at the University of Illinois Urbana-Champaign used a mathematical algorithm and an advanced 3D printing method to manufacture the cold plate. If installed in a data center, they believe it would contribute just 1.1 percent of the facility’s energy usage, compared to some 30 percent for air cooling systems.

The team have published the research, which was supported by funding from the US Department of Energy, in the Cell Reports Physical Science journal.

“Cooling is the bottleneck in chip design,” said first author Behnood Bazmi, mechanical engineering graduate student. “By bridging the gap between computational design and manufacturing capability, our approach provides a pathway for more energy-efficient liquid cooling of chips and other electronics.”

Existing liquid cooling systems, which utilize a cold plate to help the cooling fluid reach the chip, prioritize manufacturing cost over performance, the researchers claim. These cold plates contain small “fins”, which are packed together and help spread the fluid across the plate. In their study, they set out to optimize fin design to design cold plates with maximal cooling ability.

The team used a technique called topology optimization to design fins with an optimal shape. From a simple rectangular starting design, topology optimization uses a mathematical algorithm to gradually alter the fin’s shape. For each iteration in fin design, the algorithm estimates the cooling capability and the amount of power that would be needed to pump coolant past the fins.

“Topology optimization ends up converging on a design which is optimal in maximizing thermal performance and minimizing pumping power,” said founder professor Nenad Miljkovic.

With pointed tops and jagged edges, the resulting fins are much more complex than conventional fins, which are usually simple rectangles, cones, or cylinders. Because this design would be too difficult to manufacture using conventional techniques, the team collaborated with a company called Fabric8 to use an advanced manufacturing method called electrochemical additive manufacturing (ECAM) to produce copper cold plates with the optimized fins.

Though copper cold plates do exist in the market, most manufacturers eschew the material in favour of an aluminium alloy, which is easier to work with but has lower thermal conductivity. To make their copper creation, the team had to use ECAM, which relies on electrochemical plating to deposit copper and build the fins up, layer by layer, from bottom to top.

“ECAM can manufacture pure copper parts with very fine detail - down to 30 to 50 micrometers, less than the width of a human hair,” said Miljkovic.

When the researchers compared the cooling performance of an individual copper cold plate with the optimized fins to cold plates with conventional rectangular fins, they found that the optimized plate delivered up to 32 percent better cooling.

They claim the copper cold plate uses just 1.1 percent of data center electricity, compared to 30 percent for an air cooling system. This is not the most useful comparison given that conventional liquid cooling systems typically gobble up less power, usually accounting for somewhere between five-15 percent of a facility’s electricity bill.

Nonetheless, for a 1GW data center, this could still translate into significant power savings, Miljkovic said. “With our cold plates, data centers would only need to use 11MW for cooling instead of 550MW [for a 1GW facility],” he added.