Mechanical Discussion 8162017 Joshua Held Mechanical Engineer Facebook

Mechanical Discussion 8/16/2017 Joshua Held, Mechanical Engineer, Facebook Yueming Li, Thermal Engineer, Facebook John Fernandes, Thermal Engineer, Facebook Jia Ning, Hardware Engineer, Facebook

Current Mezz 3. 0 Concepts Option 7 a Option 13 Option 7 d 15 87 B 1 0 A 1 IC on back of PCB

Comparison of Concepts Small Size Small Area Large Size Large Area Option 7 78 x 110 8580 98. 3 x 167. 6 16475 Option 13 78 x 110 8580 98. 3 x 167. 6 16475 Option 14 74 x 110 8140 118 x 110 12980 Expansion Direction Back Side Connector Style Mezz Edge (. 6 mm pitch) PCB Orientations Horizontal/Vertical Horizontal Installation In Chassis Front/Rear Panel Installation Action Parallel to Front/Rear Panel Hot Swap No Parallel to Front/Rear Panel with side slide No EMI Containment for Serviceability High Difficulty Medium Difficulty Perpendicular to Front/Rear Panel Yes Low Difficulty

Option 14 Configuration Straddle Connectors Chassis Face Smart NIC Module Snap in card guides both sides Large Smart NIC with Straddle

Option 14 Variants • • • Small NIC Right Angle (upper left) Small NIC Straddle Large Smart NIC Straddle (upper right) Large Smart NIC Right Angle Small NIC Straddle in large chassis slot (lower right)

Option 14 Details PCB Size Small Size Large Size 2 mm card guide keep out 74 x 110 118 x 110 Available Space Top/Bottom Routing Inner Component Layers Placement 70 x 104 114 x 104 74 x 110 118 x 110 - 4 mm to width (card guide) - 6 mm to length (edge connector) 2 mm card guide keep out Ø Request to community • Share ideas/thoughts on PCB sizing? We’ve had a few requests to lengthen option 14 PCB to ease routing congestion between gold fingers, ASIC, and QSFPs. • In regards to large smart NIC form factor. Is this enough usable space for expected configurations?

Option 14 Details Ø Note – In right angle connector case, current connectors only provide 2. 25 mm of vertical clearance from NIC bottom to MB top. Ø FB requesting connector manufactures to meet PCIE standard clearance.

Next Steps Ø Investigating use of latch for injection and ejection. This would make removal tool-less as well as increase the amount of faceplate cutouts, more airflow. Ø Mating force of 1. 6 mm edge connectors in Large Smart NIC module (option 13 and 14) is in the realm of 84 N, which is significant. Under investigation. Ø Possible integration of EMI shielding into faceplate designs. Ø Ongoing work with thermal team to verify thermal impact of mechanical changes.