1. Mechanical Discussion
10/18/2017
Joshua Held, Mechanical Engineer, Facebook
Yueming Li, Thermal Engineer, Facebook
John Fernandes, Thermal Engineer, Facebook
Jia Ning, Hardware Engineer, Facebook

2. NIC v3.0 Configuration Small NIC with Straddle Mount
Straddle Connector
Chassis Face MB
NIC v3.0
Module
Snap in card guides both sides
Small NIC with Straddle Mount

3. Straddle Mount Small/Large 1
Mounting Variants
Straddle Mount Small/Large 1
Right Angle (RA) Small/Large 1

4. Module Versions Small w/ Latch 2x QSFP Large 1 w/ Latch 4x SFP 4x RJ45
Connector 1
Connector 2
Mating Force
Unmating Force
Small Size
4C + OCP Bay NA
64N (6.5kgf) (14lbf)
20N (2kgf) (4.5lbf)
Large Size 1 2C
96N (9.8kgf) (21.6lbf)
30N (3kgf) (6.7lbf)
Large Size 2 4C
116N (11.8kgf) (26.1lbf)
37N (3.8kgf) (8.3lbf)
4x RJ45

5. Survey Results Requests/Updates
Small form factor ports
Large form factor ports
Partner
Top Side KO (mm)
Bottom Side KO (mm)
Using QSFP Heatsink
EMI Concept
QSFPs
SFPs
1G RJ45
10G RJ45
Fastner
Use large NIC A 11
Defer to NIC vendors No
Spring Finger 2
2 or 4*
2 or 4
SCR or 1/4
Yes (x32) B
12.5/25*
2.67/2.0 4
Yes C
1.9
Not effective
4 or 8*
1/4
Maybe (x32) D
11.75
2.2
Latch/Ejct
Yes (x24)
Current Spec
11.5 ?
SCR Latch/Ejct
Considering x24 and x32
* indicates stretch goal
11.5mm
2mm
Requests/Updates
Received survey responses from four community members - still accepting surveys
Current spec proposal can be seen above in the last row
Focusing mechanical design on spring finger concept
Due to strong feedback we are now considering two large size NICs - x24 and x32

6. Top/Bottom Component Placement
Sizing Details
Available Space
PCB Size
Top/Bottom Component Placement
Routing Inner Layers
Small Size
76x115
72x109
Large Size 1
120x115
116x109
Large Size 2
142x115
138x109
2mm card guide keep out
- 4mm to width (card guide)
- 6mm to length (edge connector)
2mm card guide keep out
Requests/Updates
Width has been increased to provide clearance to SFP and RJ45 by 2mm (to 76mm and 120mm)
Added x32 Smart NIC - Large Size 2
In regards to the above form factors. Is this enough usable space for expected configurations?

7. RJ45 Issues
Delta and Luxshare have 1x4 RJ45 sink mount designs available at 10mm height. These fit nicely within C-channel of the faceplates as desired. Need to verify that and 1x2’s are available in the same height. Working on some challenges grounding RJ45 housings to faceplate.

8. Straddle Mount Small/Large
Vertical Stack-up
Straddle Mount Small/Large
Right Angle (RA) Small/Large

9. Next Steps Working on DFM review with vendors
Continue concept development
Please provide feedback on current spec configuration
Continue to close on keep outs, board size, stack up heights, EMI shielding, connector options