on where the NRZ bit duration is 100 ps [38]. An undesirable effect is created in an electrical backplane when an upper layer trace is connected to another upper layer trace in the PCB-created resonant stub. These reso- nant stubs need to be characterized as microwave structures because they are capable of degrading system performance. As the thickness of the PCB increases, the effect of stubs gets significantly worse because of the increase in length. The connector's termination to the PCB, generally, constrains both the maximum board thickness due to plating aspect ratios and the maximum trace width that can pass through on a given layer due to spacing. Thus, there is a trade-off between connectors' aspect ratio and fixing technique to the PCB on one side and the PCB thickness itself on the other. This trade-off has to be carefully managed by using microwave characterization of all the rel- evant structures not to ruin the backplane transmission characteristics. Additionally, the structure created by the ground plane plate and via drill provides an unwanted effective capacitance that also has to be taken into account when designing the way in which traces passes through the PCB and the connectors are mechanically fixed to the cards and to the backplane. Last, but not least, the connector reliability has to be assured over all the equipment lifetime, that can be a complex task if the material choice and the connector design are not more than accurate. 7.5.1.1.3 PCB Traces The traces on the backplane generally account for the longest signal path and contribute the most to the overall loss budget. In order to support 10 Gbit/s signals transmission, a series of measures have to be adopted to improve traces above the standard quality [39]. Selection of low-loss laminate materials to implement the conduction trace. As a matter of fact, material loss is the dominant effect on 10 Gbit/s channels. Use wide traces reduce conductor loss. Use a high aspect ratio for small vias. Crosstalk can be reduced by routing signals a