1. NIC v3.0 Mechanical Discussion
10/27/2017
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. NIC v3.0 Mechanical Goal: Requirements:
Develop universal form factors which shall include mechanicals and EMI containment.
Requirements:
The same NIC design must work in both straddle and right angle configurations
NICs might be oriented horizontally or vertically
Retention and guidance must work with specified NIC v3.0 MB thicknesses
Common mechanical features used across small and large form factors
Design of PCB should be flexible enough to support many component and connector configurations without need of mechanical changes
Recommended mechanical designs will be included in the specification to simplify and reduce barriers to adoption

4. 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
1.9
Not effective 4
4 or 8*
1/4
Maybe (x32) C
11.75
2.2
Yes
Latch/Ejct
Yes (x24) D
11/11.5*
2/2.25* - E
12.5/25*
2.67/2.0* F
12/24*
2.25/2.67*
1 or 2
1, 2, 4
TBD G
14.47/34.8
2.67/3*
4/6*
6/8*
4/8*
SCR Latch/Ejct H
11.5/12.5*
2.67/2.25*
No/Yes*
Yes (x32,4x8)
Current Spec
11.5 ?
x24 and x32
* indicates stretch goal
11.5mm
2mm
Requests/Updates
Added additional survey responses (A-D system vendors, E-H NIC vendors)
Current spec proposal can be seen above in the last row
Added .25mm thick isolator within 2mm bottom side keep out

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

6. 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

7. 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
Large Size 2 has been met with some opposition due to overall width. We would appreciate any thoughts on this. Is 142mm width not feasible?
In regards to the above form factors. Is this enough usable space for expected configurations?

8. RJ45 Issues
Delta and Luxshare have 1x4 RJ45 sink mount designs available at 10mm height
Requests/Updates
Redesigned the faceplate with hems top and bottom that contact RJ45 grounding fingers, and provided stiff rib opposing grounding finger pressure
Concern: if we go below 11.5mm we will be forced to a single material thickness which will cause upper flange to bow significantly in the center
Need to verify that 1x2 RJ45s are available in the same height.

9. Straddle Mount Small/Large
Vertical Stack-up
12mm
2.25mm
Straddle Mount Small/Large
12mm
2.25mm
Right Angle (RA) Small/Large

10. Next Steps Review DFM with vendors Continue concept development
Collect feedback on current spec configuration
Continue to close on keep outs, board size, stack up heights, EMI shielding, connector options