Copper connection for liquid-cooled optical module

Copper connections for liquid-cooled optical modules use co-packaged architectures and specialized connectors like XPO OverPass and XtremePass to ensure high-speed, high-density, and thermally efficient interconnects.

Overview

Liquid-cooled optical modules, such as the XPO-LPO 12.8 Tb/s transceivers, are designed for AI and hyperscale data centers, supporting high power consumption (400W+) and dense electrical lanes (64 lanes at 224 Gb/s per lane) while maintaining field pluggability . Copper connections in these systems are critical for transferring high-speed electrical signals from the optical module to the chip or backplane while preserving signal integrity and minimizing thermal impact.

Co-Packaged Copper (CPC) Architecture

Co-packaged copper (CPC) solutions integrate copper interconnects directly with the optical module and silicon, reducing trace lengths and improving signal integrity. Key features include:

• XPO OverPass™ assemblies: These 32AWG or 30AWG copper cables efficiently route 64-channel signals from the transceiver to the chip or backplane, supporting dense server and accelerator designs .
• XtremePass™ connectors: Provide a compact, one-piece solution for co-packaged copper systems, offering best-in-class signal integrity, high density, and seamless integration with Ethernet, NVLink, PCIe, and InfiniBand systems .
• Compression hardware: Prevents cable routing stresses from affecting the substrate, enabling reliable high-speed connectivity in liquid-cooled environments .

Integration with Liquid Cooling

Liquid-cooled optical modules, including immersion-cooled designs, rely on copper connections that can withstand thermal and mechanical stresses:

• Immersion cooling modules: Optical transceivers are packaged to be fully immersed in cooling liquids, with copper connections designed to maintain performance under 0–60°C operating ranges .
• Thermal efficiency: Copper interconnects in liquid-cooled modules help dissipate heat from high-power optical modules, reducing energy consumption and improving reliability .
• Signal integrity: Co-packaged copper connectors maintain low bit error rates and high signal fidelity even in dense, liquid-cooled racks .

Practical Considerations

When deploying copper connections for liquid-cooled optical modules:

• Ensure connector compatibility with the optical module form factor (e.g., XPO, OSFP-XD) and lane count .
• Use high-quality co-packaged copper assemblies to minimize insertion loss and crosstalk at high data rates (224 Gb/s per lane or higher), .
• Consider mechanical stress relief and routing flexibility to prevent damage in immersion or cold-plate liquid-cooled environments .
• Plan for scalable density, as co-packaged copper solutions support up to 204.8 Tb/s rack-level bandwidth while maintaining thermal and electrical performance .

Summary

Copper connections for liquid-cooled optical modules are essential for high-bandwidth, high-density data center applications. Using co-packaged copper architectures with specialized connectors like XPO OverPass™ and XtremePass™, these systems achieve reliable chip-to-chip and chip-to-system connectivity while supporting liquid cooling, minimizing thermal stress, and maintaining signal integrity in next-generation AI and hyperscale networks .