Issue link: https://resources.mouser.com/i/1495600
aspect of their design, including PCB substrate, weave orientation, and cleaning direction (e.g., abrasive cleaners for copper layers have different electrical properties at different angles). Low-Dk dielectrics and careful manufacturing controls could be useful, but they are often very expensive and difficult to source. At the same time, the geometry of PCB traces can greatly affect the signal integrity of high-speed transmissions, which is why engineers must pay strict attention to angles used, potential reflection points, and eyedrops and curves over 90˚ and 45˚ angles. This is an issue for connectors that mate with sharp angles. For example, a connector that, when mated, results in a sharp 90˚ turn for a signal will introduce reflections. Conductors that don't lead anywhere may also be highly problematic for high-speed signals as they can act as antennae and radiate signals. This occurs not only at the end of mated connectors but also with through-hole vias on PCBs where internal signal layers are used. In such scenarios, engineers should use the full via (i.e., signals enter at one outside layer and exit on the other side), back drill via stubs, blind/buried via, or internal vias. Finally, PCB traces are far from ideal transmission lines—the maximum length of high-speed traces is often several inches. This occurs due to poor dielectric characteristics of PCB substrates, their inability to control impedance with precision, their unshielded nature, and their proximity to sources of interference such as power planes and analog signal traces. Clock and data recovery circuits (CDRs) and retimers can be used to extend signal traces, but these increase the system cost, power, and thermal budgets while introducing latency. Samtec Flyover systems can be used to minimize signal integrity losses by placing connectors as close to critical components as possible and then routing those signals through cables. The significantly lower losses from Flyover systems allow for greater distances while also eliminating power requirements." C h a p t e r 2 | U n d e r s t a n d i n g C o m m o n C h a l l e n g e s t o R o u t i n g H i g h - S p e e d S i g n a l s Anthony Fellbaum Senior FAE and BDM - Canada, Samtec 10 Samtec Flyover ® Solutions Break Next-Gen System Architecture Constraints