SDN / NFV Compute Node Board PCBA

Universal COTS Server Blade for Virtualized 5G NFs — Dual CPUs, 2 TB DDR5 ECC, DPDK/SR-IOV SmartNIC Offload, Redfish/IPMI, TPM 2.0 for Telco Cloud NFVI

Product Overview

The SDN/NFV Compute Node Board is a commercial-off-the-shelf (COTS) server blade PCBA purpose-built for the network functions virtualization infrastructure (NFVI) layer of 5G telco clouds. Constructed on a 26-layer Megtron 6 PCB, the board hosts dual high-core-count processors with hardware virtualization extensions (VT-x/VT-d, SMT) and up to 2 TB of DDR5 ECC memory across 16 RDIMM slots, providing the memory bandwidth and capacity required to host dozens of virtualized network functions (VNFs) or cloud-native network functions (CNFs) simultaneously. Two programmable SmartNICs with DPDK and SR-IOV acceleration offload OVS data-plane switching, VXLAN/GENEVE tunneling, and service function chaining at 200 Gbps — freeing host CPU cores for NF workload processing. The board provides 4× 100GbE QSFP28 ports for NFVI fabric connectivity and 4× 25GbE SFP28 for management and storage networks. It supports Redfish and IPMI 2.0 for standards-based bare-metal provisioning, and includes a TPM 2.0 module for attested boot in zero-trust NFVI environments. The board's NUMA-aware design with memory interleaving and cache QoS ensures deterministic performance isolation between co-located VNFs sharing the same socket, preventing "noisy neighbor" degradation.

Key Specifications

PCBA Assembly Challenges

Assembling the 26-layer SDN/NFV compute node board involves simultaneous placement of two large server-class CPU BGA packages, each with 4,000+ balls at 0.8–1.0 mm pitch, along with 16 DDR5 RDIMM slots, dual SmartNIC BGAs, and multiple 100GbE/25GbE QSFP28/SFP28 connector cages — all on a single 26-layer Megtron 6 board. The dual-CPU configuration creates a challenging thermal profile during reflow — the two massive BGA packages act as heat sinks that pull heat from adjacent smaller components, requiring multi-zone profiling with thermocouples embedded at multiple locations to ensure all joints reach liquidus simultaneously. The 16 DDR5 RDIMM slots must be placed with precision alignment within 0.1 mm across their full length to ensure all DIMM contacts engage correctly — the slots are through-hole press-fit connectors that are installed after SMT reflow using a dedicated press tool with alignment pins. The dual SmartNICs require the same high-speed signal integrity care as the CPU DDR5 interfaces, with all differential pairs length-matched to ±5 mil. The board's total power draw can exceed 600 W, requiring heavy copper power planes (2 oz) on 8 internal layers. Every BGA and connector joint is verified by 3D X-ray and AOI.

Test Strategy

Each assembled NFV compute node board undergoes a comprehensive test sequence spanning compute, memory, networking, and management domains. ICT and boundary scan verify all passive nets and basic interconnects. Both CPUs are populated with diagnostic firmware that validates core functionality, cache integrity, and inter-socket UPI/CXL link training. All 16 DDR5 RDIMM slots are populated with test DIMMs and subjected to 24 hours of MemTest86+ at all supported speeds, with ECC error logging enabled. The 4× 100GbE and 4× 25GbE ports are tested with PRBS31 patterns — the 100GbE ports at 53.125 Gbps PAM4 and 25GbE at 25.78125 Gbps NRZ — verifying eye diagrams, FEC error rate, and receiver sensitivity. The dual SmartNICs are loaded with diagnostic firmware and tested for DPDK throughput, SR-IOV VF instantiation (up to 128 VFs per port), and OVS offload performance. NUMA-aware performance isolation is validated by running compute-intensive workloads on both sockets and verifying cache QoS enforcement and memory bandwidth partitioning. Redfish and IPMI management functions are validated including power control, sensor monitoring, SOL console, and firmware update. Final burn-in runs 72 hours at 45°C with sustained NF workload emulation across both CPUs.

PCB Manufacturing Difficulty

Fabricating the 26-layer Megtron 6 NFVI compute node PCB demands precision across high-speed digital, power distribution, and memory interface domains. The dual-CPU DDR5 memory interfaces operate at 5,600 MT/s with 16 RDIMM channels — each channel's fly-by topology requires daisy-chained address/command routing with precise stub lengths and termination resistors placed at the last DIMM position. All DDR5 data lanes are length-matched to ±2 mil within byte lanes and ±10 mil across channels. The 100GbE PAM4 interfaces operate at a 26.5625 GHz Nyquist frequency, demanding spread-glass Megtron 6 laminate with Df < 0.002 at 10 GHz and ultra-smooth copper (Rz < 2.5 µm). Backdrilling removes via stubs on all signal layers above 14 GHz to eliminate resonant dips in the insertion loss profile. The heavy copper power distribution uses 8 layers of 2 oz copper with embedded planar capacitance and via-stitching to maintain PDN impedance below 0.5 mΩ to 100 MHz. The aspect ratio of PTHs exceeds 11:1, requiring pulse plating. Finished boards undergo 100% TDR on all high-speed pairs, impedance coupon testing, HiPot at 1,500 VDC for NEBS compliance, and AOI on all layers.

More information