KiCad Template: NVLink Connector and Power Delivery Footprints for RISC-V GPU Boards

Hook — The pain point we solve

Designing a PCB that ties a RISC‑V SoC to a discrete GPU with an NVLink‑style connector is one of the steepest challenges a hardware engineering team faces in 2026: high pin‑count mezzanine connectors, multi‑10/100Gb SerDes lanes, and a power delivery network (PDN) that must supply hundreds of amps with milliohm stability. This guide gives you production‑ready KiCad templates, footprints, PDN layout rules, and manufacturing notes so you can get from schematic to fab with fewer iterations.

Why this matters in 2026

Late 2025 and early 2026 saw an acceleration in RISC‑V + GPU system designs after announcements like SiFive's adoption of NVLink Fusion infrastructure. That momentum creates practical demand: custom carrier boards, mezzanine interposers, and retrofit adapters that keep signal integrity and power integrity inside tight budgets. Teams now need toolchain‑friendly templates for KiCad (7.x/8.x in 2026), not just high‑level checklists. This article supplies downloadable KiCad assets plus the engineering rationale behind each decision.

What you’ll get

• Downloadable KiCad project with connector footprints & templates (GitHub link below)
• Recommended layer stack and impedance rules for NVLink‑style high‑density connectors
• PDN strategy: rails, decoupling plan, bulk capacitance, via stitching
• Manufacturing notes: tolerances, board thickness, assembly and test hooks
• Step‑by‑step checklist to integrate the template into your RISC‑V GPU board

Where to download the templates

All KiCad templates, footprints, and sample library files referenced in this article are available under an MIT license at the circuits.pro repo:

https://github.com/circuits-pro/kicad-nvlink-templates

The repo contains:

• /footprints — 0.5mm and 0.4mm pitch mezzanine footprints, board‑to‑board compression pad patterns
• /templates — KiCad project templates with stackups, net classes, and standard BOM headers
• /examples — a sample carrier board connecting a RISC‑V SoC to a GPU via an 8‑lane NVLink‑style mezzanine
• /manufacturing — gerber notes, assembly drawings and checklists

Connector footprints & template philosophy

High‑density NVLink‑style connectors are effectively a cluster of many high‑speed SerDes lanes plus power pins. The template set follows these principles:

1. Pin segregation: Group power, ground, management (I2C/SMBus), and SerDes lanes to minimize crosstalk and ease plane allocation.
2. Matched pair domains: Keep each differential lane in its own routing channel with pair spacing and guard traces defined by the net class.
3. Manufacturability: Footprints use standardized pad sizes and non‑plated alignment holes for mechanical stability in assembly.
4. Testability: Provide selectable test points for each lane and access pads for near‑end/far‑end eye capture.

Typical footprint variants

• 0.4mm pitch 300‑pin mezzanine — good for compact carrier boards where vertical compression connectors are used.
• 0.5mm pitch 400‑pin mezzanine — favored where mechanical robustness is prioritized and marginally larger board space is acceptable.
• Board‑to‑board pad array (compression) — recommended for very high pin density; includes recommended metalized keepout and soldermask defined pads.

Naming conventions in the repo

Footprints are named to aid automation and BOM generation. Examples:

• NVLINK_BTB_400P_0p5mm.kicad_mod — board‑to‑board 0.5mm pitch footprint
• NVLINK_MZ_300P_0p4mm_SLC.kicad_mod — mezzanine, single‑lane channel grouped (SLC) layout
• NVLINK_MECH_4xMOUNT.kicad_mod — mechanical standoffs and alignment pattern

Recommended PCB stackup (practical, manufacturable)

High‑speed SerDes and heavy PDN both push you to a carefully chosen stackup. The templates include two production stackups: 12‑layer (recommended) and 8‑layer (cost‑sensitive with tradeoffs).

12‑layer production stackup (preferred)

1. Top: signal (immediately under component pads)
2. Inner-1: GND plane (solid)
3. Inner-2: differential microstrip return and routing
4. Inner-3: PWR plane (high current rails)
5. Inner-4: GND plane (stitching for isolation)
6. Bottom: signal (assembly side)

Key parameters:

• Dielectric thickness between Top and Inner-1: tuned to give 90Ω differential for pairs using a 0.12 mm trace width and 0.18 mm spacing (adjust with your board shop).
• Core & prepreg: Use low‑loss materials (ER = 3.6 or better) for SerDes >16Gbps. The repo includes a KiCad stackup file with editable values.

8‑layer cost‑sensitive stackup

When budget pressures force an 8‑layer build, the template compresses power and ground planes; the tradeoff is higher insertion loss and a tighter margin on crosstalk. Use controlled dielectric and be prepared to de‑rate maximum channel length.

Net class & routing rules — copy these into KiCad

Drop these net class rules into your project for a starting point. Measurements and simulation will refine them for your chosen board house and materials.

• SerDes_Lane: differential, target 90Ω, trace width 0.12 mm, gap 0.18 mm, via micro‑stitch: 0.25 mm drill, annular ring 0.15 mm
• PowerHigh: single ended 40 mil trace (1.0 mm) for rails >10A (plane preferred)
• PowerLow: single ended 10–20 mil (0.3–0.5 mm) for 1–5A rails
• Mgmt: 6 mil traces, standard spacing

Via strategy

Use staggered via fences for signal transitions and via stitching for ground planes near the connector. Recommended via types in the repo:

• Microvia (laser) for layer transitions inside the SerDes channel
• Thermal via arrays under power MOSFETs/VRMs to connect to internal copper planes
• Barrel via for high current — 0.7 mm drill, multiple in parallel for power pins

PDN design — rails, decoupling, and thermal paths

Designing a PDN that feeds both a RISC‑V SoC and a GPU requires a mix of plane strategy, bulk capacitance, and local decoupling. Follow these principles from our lab builds:

1. Separate high current rails: Keep GPU core power on dedicated planes and avoid routing GPU core current through long skinny traces.
2. Distributed decoupling: Place a hierarchy of decouplers — 0.01µF, 0.1µF, 1µF, 10µF — as physically close to the GPU SoC/connector power pins as possible.
3. Bulk capacitors at the connector: For board‑to‑board systems, place bulk electrolytic/MLCC caps in the parent board near the mezzanine to handle inrush and transient currents during link training.
4. Low inductance return paths: Emphasize broad copper planes and via stitching to minimize loop inductance for high di/dt events.

Specific PDN layout items

• Place VRMs on the carrier board close to the GPU supply entry when the GPU is on the carrier — otherwise route heavy power to the GPU card with wide planes and parallel vias.
• Use power ferrites or bead arrays on management rails (I2C/SMBus) to protect sensitive logic from the PDN noise.
• Include sense resistor locations and Kelvin sense traces if remote current monitoring is needed.

Signal integrity and routing patterns

High‑speed lanes require careful channel treatment. The templates assume multi‑gigabit SerDes characteristics; use this checklist when routing:

1. Prioritize uninterrupted return; maintain solid reference plane under differential traces.
2. Limit vias per differential pair; try to keep count to 1 or 2 for short channels.
3. Enforce pair length matching per lane (typical tolerance < 50 ps for NRZ; tighter for PAM4). The repo includes a KiCad differential length tuner example.
4. Provide spacing to adjacent lanes: keep at least 3x trace width as isolation or route ground guard traces.

Layout example — 8‑lane NVLink‑style channel

In our sample carrier layout (in the repo) each lane occupies a 1.2 mm routing channel. The channel includes:

• Continuous ground plane beneath
• Via fence every 1.5 mm
• Dedicated power pins grouped together and isolated by a stitched ground moat

Manufacturing notes — DFM and assembly

High pin count connectors are unforgiving in assembly. We include production notes that have reduced returns in our pilot runs.

Mechanical tolerances

• Board thickness tolerance: specify ±0.1 mm. Compression connectors require strict thickness control for reliable mating.
• Planarity: Request a board warpage spec < 0.5% across the panel for >300 mm boards. Warpage breaks solder joints on dense pad arrays.
• Edge connector clearance: leave 1.0–1.5 mm keepout from board edge for mating fixture clearance.

Soldermask & stencil

• Use SMD lands with soldermask defined pads for discrete power pins to avoid bridging on fine pitch areas.
• For board‑to‑board compression pads, use exposed copper pads with minimal solder mask and no stencil in many designs — check your connector vendor recommendations.

Assembly and test

• Include a dedicated production test header (JTAG + SerDes IQ taps) for link training and burn‑in.
• Use optical/automated inspection tuned for low‑contrast pads and add fiducials around the connector region.
• Plan for x‑ray inspection on first panels to confirm via filling and pad coplanarity.

Case study: prototype carrier board (our lab build)

We built an 8‑lane carrier board in late 2025 to validate RISC‑V SoC to GPU connectivity via an NVLink‑style mezzanine. Highlights:

• Stackup: 12‑layer, low‑loss prepreg (ER 3.45). Channel length ~70 mm per lane.
• PDN: GPU core plane supplied by dual parallel VRMs with bulk 470 µF per connector plus distributed MLCCs.
• Validation: eye diagram capture at 40 Gbps equivalent (lab emulation) and PDN impedance sweep using a vector network analyzer.

Key result: with the recommended via fences and per‑lane guard zones, crosstalk was reduced by ~6 dB compared to an initial layout iteration. PDN impedance stayed under 20 mΩ up to 100 kHz, sufficient for link training transients.

Tooling & verification workflows

Use these practical verification steps before sending to fab:

1. Run KiCad DRC and the provided net class checks in the template repo.
2. Export ODB++ or IPC‑2581 and perform DFM checks with your board house.
3. Simulate the SerDes channel with S‑parameters (extract or request material models from your board house).
4. Perform PDN impedance analysis with your preferred tool (PIEDA, Keysight ADS, or open tools). The repo includes a PDN component list to model.

Advanced strategies & 2026 trends

In 2026, we see three trends shaping how you design NVLink‑style systems:

• Open mezzanine standards: The industry is moving toward standardized high‑density mezzanines for heterogeneous compute, making interchangeable footprint templates more valuable.
• Higher data rates and PAM4 adoption: As lane rates creep past 50–100 Gbps, PAM4 and advanced equalization are more common; channel loss budgets are tighter, requiring ultra‑low loss laminates and microvia‑heavy routes.
• Supply chain consolidation: OSATs increasingly offer matched assembly + impedance‑controlled PCBs, so early collaboration with a single vendor reduces iteration time.

Prediction: configuration & verification as code

Expect more teams to treat connector layouts and PDN definitions as versioned artifacts — templates in Git with CI that run DRC, generate manufacturing packages, and verify net class conformance. The repo includes an example Python script for automated net class generation in KiCad.

Practical checklist — integrate the template into your project

1. Clone the repo and import the desired footprint into your library: git clone https://github.com/circuits-pro/kicad-nvlink-templates
2. Copy the stackup file (.layerstack) into your project and update dielectric parameters to match your board house.
3. Load net classes into KiCad and apply the SerDes_Lane class to each differential pair.
4. Place connector footprint early in the layout phase; allocate routing channels before placing large components.
5. Run DRC, export ODB++ and submit to board house with the manufacturing notes folder attached.
6. Plan an early small pilot run (3–10 boards) for electrical and mechanical verification before full production.

Common pitfalls and quick fixes

• Pitfall: Mixing power pins across the connector. Fix: Re‑group power pins into contiguous blocks and stitch the return planes.
• Pitfall: Excessive via count in the lane. Fix: Use microvias and limit layer transitions with pre‑defined escape channels.
• Pitfall: Insufficient bulk capacitance at the connector. Fix: Add 100–470 µF bulk caps on the parent board adjacent to the connector pad cluster.

Licensing & contribution

Templates are released under MIT. Contributions are welcome: open a PR with your verified footprint or stackup, include manufacturing validation and test evidence, and follow the repo’s contribution guidelines.

“In 2026, bridging open RISC‑V SoCs to advanced GPUs will depend as much on repeatable board design templates as it does on SoC IP. These KiCad templates are designed to be the repeatable foundation.”

Actionable takeaways

• Use the supplied KiCad templates to standardize connector footprints and net classes across projects.
• Adopt a 12‑layer stackup for production to keep signal and power integrity margins healthy.
• Place bulk decoupling near the connector and use via stitching liberally for return paths.
• Run early pilot builds and request matched material stackup data from your board house.

Final notes & call to action

High‑density NVLink‑style connectors on RISC‑V GPU boards are entirely achievable in KiCad with careful planning — the templates in our repo capture the lessons from 2025–2026 pilot programs and production runs. Download the kit, run the included DRC/stackup checks, and share your feedback.

Get the templates, examples, and manufacturing checklists: https://github.com/circuits-pro/kicad-nvlink-templates

Join the conversation on our circuits.pro forum to share validation data, request new footprints, or commission template customization for your RISC‑V GPU project.

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