High-Density Board-to-Board Interconnects: Mezzanine Design
Mezzanine connectors allow for modular PCB stacking. We analyze the "stack height" and "pin density" requirements for modern high-speed compute modules and data center hardware.
Stacking Performance: Mezzanine Connector Strategy
In complex systems like servers or industrial controllers, designers often "stack" PCBs to save space. These board-to-board connections are handled by Mezzanine connectors. Because these connectors often carry high-speed signals (PCIe Gen 5, DDR5), their electrical design is just as critical as their mechanical height.
1. Stack Height and Tolerance
Mezzanine connectors come in various "mated heights" (e.g., 5mm to 30mm).
- The Challenge: If you have multiple mezzanine connectors on a single board, any slight warping of the PCB or manufacturing tolerance in the connector height will prevent the boards from mating correctly. Designers must use "floating" connectors or generous lead-in chamfers to compensate for these mechanical misalignments.
2. High-Speed Integrity
At speeds above 10 Gbps, the "stub" of a connector pin can cause signal reflections. Modern mezzanine connectors use "hermaphroditic" contacts or specialized grounding shields between signal rows to minimize crosstalk. When selecting a mezzanine, always check the "SI" (Signal Integrity) report from the manufacturer to ensure it supports the data rates of your specific bus.
