1. NIC v3.0 Mechanical Discussion
12/1/2017
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
Some form of mechanical mechanism is required for seating large form factors due to mating forces
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 ?
X32 ONLY
* indicates stretch goal
11.5mm
2mm
11.5mm Top Side KO
2mm Bottom Side KO
Dell EMC X FB
HPE
Lenovo
Quanta
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
Mounting Variants
Straddle Mount Small/Large
Right Angle (RA) Small/Large

6. Components of Variants
Straddle Style
All form factors share same card guide
Symmetric design - 1 PN, QTY 2
Guides include integrated latch pull point
Three versions needed to support NIC v3.0 MB thicknesses (62,79,93)
No additional components needed for vertical orientation
Right Angle Style
All form factors share same card guide
Symmetric design - 1 PN, QTY 2
Guides include integrated latch pull point
No additional components needed for vertical orientation
Straddle Style Small BOM example
Component
QTY
NIC
PCBA 1
Faceplate
Gaskets 2
Screws
Isolator
System
Straddle CG 062 6

7. 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 4C
116N (11.8kgf) (26.1lbf)
37N (3.8kgf) (8.3lbf)
4x RJ45

8. 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
139x115
135x109
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?

9. Current Small Designs FB Latch Concept 80.76mm total width
NIC depth set by latch/CG
Simple card guides
DELL Single Screw Concept
84.78mm total width
NIC depth set by FP/CG
Complex card guides
Not compatible with latch concept
FB Single Screw Concept
84.78mm total width
NIC depth set by connector
Same card guides as latch
Compatible with latch concept

10. RJ45 Heights/Construction
11.5mm tall RJ at 10mm above PCB
.8mm thick faceplate do-able
Good clearance to latch
11.45mm tall RJ at 9.7mm above PCB
.8mm thick faceplate shown
Tight clearance to latch
11.3mm tall RJ at 9.5mm above PCB
.6mm thick faceplate required
Tight clearance to latch

11. Large Size Latching Forces
Large Size 8xRJ45
Large Size
Latch Style
Working Length
Force/Latch
Approx. Usable FP Space
RJ Ports
2 Short Left/Right
15mm
5lbf
98mm na
25mm
3.2lbf
78mm x6
2 Middle Left/Right
63mm
1.3lbf
78mm split
x4 or x6?
1 Large Left
129mm
1.6lbf
122mm x8
Small Size
1 Left Full Width
68mm
1.2lbf
59mm x4

12. Straddle Mount Small/Large
Vertical Stack-up
12mm
2.25mm
Straddle Mount Small/Large
12mm
2.75mm
Right Angle (RA) Small/Large

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

14. Supporting

15. Narrow Versions Lenovo card guide Optimize faceplate New card guides
Faceplate Width
CG to CG Width
Top Side KO
Current 89
92.75
72x11.5
Lenovo CG 87
Narrow 80
80.75
See Below
All 76mm wide PCB
Lenovo card guide
Optimize faceplate
New card guides
Remove FP venting
Thumb screws pushed in
Heatsink width reduced 5mm
Chassis opening changed
63mm
11.5mm
2.5mm
72mm

16. New Large FF Double Latch
Faceplate architecture allows for latch/ejectors on both sides for more secure mounting
Touch point size can be optimized for better faceplate utilization
Likely needed for wide Large 2 form factor

17. 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.