At DesignCon in 2007, FCI and Intel presented a joint paper titled “Improving System Performance by Reducing System Impedance to 85 Ohms.”  FCI has developed several backpanel connectors in support of the Intel 85 ohm system platform.

QPI Connector development

Reduced impedance discontinuities
- 85 ohm via holes are easier to design than 100 ohm via holes
- Reduced impedance mismatch
- improved smoothness of insertion loss curve
Reduced PCB thickness/cost
Less PCB material required, lower cost
Increased routing density using 0.2mm traces
Increased routing density w/same trace width

Differential Impedance: 85 +/- 8 ohms at 35ps (20-80%) / 50ps (10-90%)
Differential Insertion Loss:
- < 1dB through 6Gbps (3GHz)
- < 3dB through 20Gbps (10GHz)
Multi-active NEXT: < 3.25% at 35ps (20-80%) / 50ps (10-90%)
Multi-active FEXT: < 5% at 35ps (20-80%) / 50ps (10-90%)
In-pair Skew: < 12ps

To know more : Product Overview