Researchers at the University of Illinois Urbana-Champaign have developed a cold plate design workflow that pairs topology optimization (TO) with electrochemical additive manufacturing (ECAM) to produce pure-copper liquid-cooling components with microscale fin geometries. 

The work aimed to tackle an issue in cold plate development in which computational design tools routinely generate optimal fin architectures with sub-100-micrometer features, but which conventional manufacturing methods cannot reliably produce in copper.

“Cooling is the bottleneck in chip design,” stated Behnood Bazmi, Mechanical Engineering Graduate Student at the University of Illinois Urbana-Champaign and first author of the study.

University of Illinois team 3D prints pure-copper cold plates for electronics cooling

“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.”

“Topology optimization ends up converging on a design which is optimal in maximizing thermal performance and minimizing pumping power,” added Nenad Miljkovic, Founder Professor at the University of Illinois Urbana-Champaign.

The resulting fins feature tapered profiles with fine branching tips. Those geometries increase wetted surface area and locally direct coolant flow, but are far too complex for conventional machining or melt-based metal additive manufacturing processes.

ECAM as the enabling fabrication method

To realize those geometries in pure copper, the team worked with San Diego-based Fabric8Labs, whose ECAM platform uses a dense array of individually addressable microelectrodes to deposit copper ions from a water-based electrolyte, building structures layer by layer at a voxel resolution of approximately 33 micrometers. 

The process operates at room temperature, avoids the thermal distortion associated with laser melting or sintering, and produces copper at up to 99.95% purity. Most melt-based additive processes struggle to handle the material due to its high reflectivity and thermal conductivity.

“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. The water-based electrolyte feedstock is recyclable and can be replenished using low-cost metal salts or scrap copper, and the array-based printhead supports batch fabrication of multiple components, which the researchers noted as relevant to production scaling.

A data center energy analysis conducted by the team, based on a direct-to-chip liquid-cooling architecture for a 42U rack dissipating 167 kilowatts, indicated the proposed solution would consume only 1.1% of total data center energy for cooling, against a total usage effectiveness (TUE) of 1.011.

“With our cold plates, data centers would only need to use 11MW for cooling instead of 550MW [for a 1GW facility],” said Miljkovic.