1. Mechanical Discussion
9/20/2017
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
Mounting Variants
Straddle Mount Small/Large
Right Angle (RA) Small/Large

4. Module Versions Small w/ Latch 2x QSFP Large w/ Latch 4x SFP 4x RJ45
Connector 1
Connector 2
Mating Force
Unmating Force
Small Size
4C + OCP Bay NA
64N (6.5kg) (14lbs)
20N (2kg) (4.5lbs)
Large Size 2C
96N (9.8kg) (21.6lbs)
30N (3kg) (6.7lbs)
4x RJ45

5. Top/Bottom Component Placement
Sizing Details
Available Space
PCB Size
Top/Bottom Component Placement
Routing Inner Layers
Small Size
74x115
70x109
Large Size
118x115
114x109
2mm card guide keep out
- 4mm to width (card guide)
- 6mm to length (edge connector)
2mm card guide keep out
Requests/Updates
Length has been updated to 115mm
Due to tight layout of SFP and RJ45 we propose to increase the width 2mm (to 76mm and 120mm)
In regards to the above form factors. Is this enough usable space for expected configurations?

6. RJ45 Issues
Availability of low profile 1x4 RJ45 connectors is a risk. Most designs are above 12mm tall which exceed our maximum height of 11.5mm. Centering the RJ45 connector vertically on the faceplate would be ideal; this would require sink-mount RJ45 with mm of height. Need community feedback on RJ45 configurations required to see if connector vendors can support.
1.4mm gap
**View shown includes 8.8mm Pulse sink-mount elevated to the ideal height**

7. EMI Shielding Option 1 Option 2
Finger Stock
Option 1
Finger Stock
Die Cut Gasket
Option 2
Finger Stock
Finger stock used top and bottom is the most reliable method, with more rigid faceplate. Uses slightly more vertical internal chassis space due to upper internal flange.
Die cut gasket (270 degrees) and bottom finger stock is more risky due to very thin 2mm tall gasket across the top. Faceplate is less rigid, uses the same vertical space as first option but outside the chassis.
**Both options included in 3D CAD for evaluation**

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

9. Next Steps
Community mechanical questionnaire – please provide detailed feedback
Close on – Keep outs, board size, stack up heights, EMI shielding, connector options
Considering ¼ turn fastener in place of thumb screws
Will be in Dallas for OCP workshop

10. 3D CAD Notes Option 1 EMI Shielding - Hide circled items