How CelLink Brings Flat Power Delivery to the Rack

Leading up to AI Infra Summit this September, we're continuing our conversations with players across the data center stack to learn what AI infrastructure demands and what's being built to meet it. Those talks run from hyperscalers through storage, memory, and networking, out to power, cooling, and rack-scale architecture.

For this installment, I was delighted to catch up with Steve Thorne, chief commercial officer of CelLink. The company spent more than a decade building flat, flexible power circuits for electric vehicles, and it has now brought that form factor to the data center. Its PowerPlane swaps out thick bundles of discrete wires for a single laminated circuit thin enough to route thousands of amps in less space than a cable harness used to fill. Motherboards dock straight to it. And because that same flat layer can align with liquid-cooling manifolds and pull heat off the backside of the board, where vertical power regulators run hottest, Thorne makes the case that power and cooling no longer have to fight for the same cramped space. Here's what I learned.

Q1: CelLink came away from OCP 2025 asserting that the unit of design has moved from the server box to the rack and beyond, with whole racks and pods sold as finished products. What does designing at rack scale change about how power has to be delivered, and what still trips operators up in that shift?

A: Designing at rack scale forces power delivery to be considered as a first-class constraint alongside compute and cooling, rather than an afterthought bolted on at the end. Flat, flexible power delivery infrastructure must now be co-designed across the full rack and pod, rather than being treated as independent subsystems. The old approach of designing subsystems in isolation has caused integration oversights and schedule delays. By coupling flat power delivery with cooling infrastructure from the start, operators can improve current-carrying capacity, reduce energy loss, and avoid the last-minute surprises that still trip up many rack-scale deployments.

Q2: Your PowerPlane delivers thousands of amps through a flat circuit under a millimeter thick, and motherboards dock straight to it instead of being wired one cable at a time. What does taking power delivery flat and into the rack free up, and why does that matter for an AI server?

A: The flat geometry of the CelLink flex harness eliminates the volumetric overhead of round wire bundles, freeing space inside the compute tray for larger compute modules and liquid cooling infrastructure. Silicon vendors also benefit: by routing power interconnects to the underside of the chip, more I/O and fiber optic connections can be placed around the GPU or AI accelerator periphery. Moving the Power Distribution Network (PDN) out of the PCB also enables more thermally-efficient delivery—less energy lost to heat means more power available for compute.

Beyond space, CelLink flex harnesses enable automated system assembly. Their flat, thin profile is far more compatible with robotic pick-and-place equipment than conventional cable bundles, reducing manual labor and improving assembly consistency at scale.

Q3: CelLink contends that efficiency now must span the whole power path, from the grid down to the last centimeters inside the server. Where is the most power and space lost today, and how do higher-voltage delivery and vertical power to the back of the board change that picture?

A: Significant power is lost inside the GPU tray along the conversion chain from 800V down to 50V, 12V or 6V, and finally sub-1V at the silicon. At each step down in voltage, current rises sharply, and I²R losses compound accordingly. CelLink flex harnesses address this by carrying high voltage deeper into the GPU tray, keeping current lower across a longer path and reducing resistive losses before the final point-of-load conversion.

Q4: You describe power and cooling as things that should not fight for space. How do you co-design a flat power layer to work with liquid cooling in the same rack, and what does that integration unlock that assembling them separately cannot?

A: In conventional racks, power arrives via large-gauge, heavy, inflexible wire bundles, while liquid cooling relies on bulky pipes and hoses. Both compete for the same constrained volumetric space inside the tray. CelLink flex harnesses resolve this conflict by flattening power delivery to under 1mm in z-height, spreading it across tight spaces and allowing cooling infrastructure to occupy spaces where it actually needs to be.

The flat geometry also creates a natural thermal advantage: large, flat surfaces are far more effective for heat extraction than liquid cooling plates shaped around round wires or thick copper busbars. Co-designing the power and cooling layers together unlocks efficiency gains that assembling them separately simply cannot achieve.

Q5: CelLink came into the data center from high-volume EV manufacturing, where flexible circuits replaced bundles of hand-built wiring. What does that heritage teach about taking manual assembly out of rack build-outs, and where does rack-integrated power and cooling have to go next as density climbs?

A: CelLink's high-volume EV manufacturing heritage directly informs its data center approach. Flat, lightweight flex harnesses are well-suited to robotic pick-and-place assembly, and aluminum conductor designs proven in EVs and drones for weight and cost reduction translate naturally to rack environments where efficiency and thermal performance are equally critical.

The same principles that simplified EV wiring apply to rack build-outs, where loose cables and manual terminations introduce variability and assembly errors. CelLink flex harnesses can be placed directly adjacent to GPU components without cable management overhead. As rack density continues to climb, the next step is deeper integration, where the power delivery harness is co-designed and co-assembled with liquid cooling cold plates as a single unified subsystem.