Additively manufactured cold plates for GPUs
Cold plates printed in copper as a single part, with fin geometries that cannot be machined, characterized on a test bench and on GPU hardware.
Why print a cold plate
A conventional microchannel cold plate is made in pieces: a finned base and a cover, joined by brazing or bonding. The joint is a problem. Braze material can wick into the channels, and bonded joints add thermal resistance and limit the operating pressure. The fin shapes are also limited to what a cutting tool can reach.
Metal additive manufacturing removes both limits. The fins and the cover are printed as one body, so the fin tips are bonded with no extra process step, and the fin geometry can vary in three dimensions.
A monolithic copper cold plate with sinusoidal microchannels
This is my first-author chapter in Advances in Heat Transfer (in press), in a volume on data center and electronics cooling.
Modern GPU accelerators dissipate more than 700 W per package, and AI training hardware is approaching kilowatt-level power, which makes direct-to-chip liquid cooling a requirement. We developed a copper cold plate for this application, printed with 3D Systems in GRCop-42 copper alloy by laser powder bed fusion. It has an array of bi-periodic sinusoidal microchannels: the fins are wavy along the flow direction, and the amplitude of the wave grows from zero at the base to a maximum at the fin tip. This geometry cannot be made by subtractive machining. The cold plate also cools the auxiliary components of the GPU board and routes the coolant, all in a single printed part with no brazed joints.
- Geometry. X-ray computed tomography confirmed that all critical internal dimensions were within 5 % of the design.
- Thermal-hydraulic performance. On a calorimeter bar with single-phase water, at 100–600 W and 1–5 L/min, the thermal resistance was 0.113–0.137 K/W (0.450–0.548 cm²·K/W) and independent of heat load. The pressure drop was 1.1–24.1 kPa, and the coefficient of performance reached 3.2 × 10⁴.
- On hardware. On an NVIDIA RTX A4000 at full thermal design power, the junction-to-coolant resistance was 0.150 K/W.
- Modeling. A conjugate heat transfer CFD model reproduced the measurements with a mean absolute percentage error below 2 % over all 30 test conditions.
Ongoing work
We are developing further cold plate designs for additive manufacturing, including manifold microchannel, pin-fin and lattice geometries, in aluminum and copper alloys, with 3D Systems, IQ Evolution, Tritone Technologies and Fabric8Labs. These feed into the manifold microchannel cold plate work.
Status
Chapter in press. Design, printing and testing of new cold plates are ongoing.