Impact of SMT Connector Pads on High Speed Serial Links

Connectors are needed when high speed serial links pass through multiple printed circuit boards (PCBs) or cables. Surface mount (SMT) connectors play an important role in improving signal integrity as signal speeds continue to increase. Orientation of SMT connector lead frame when mounting on the PCB pad determines the direction of the signal breakout. Improper breakout of the signal due to the via location or otherwise can create an unintentional stub at the connector pad that can impact signal quality. In this paper, the impact of SMT connector pad on high speed serial link is discussed along with some examples. Proper breakout from the connector can result in short pad stubs. In cases where proper breakout is not possible, via-in-pad design is proposed as an approach to mitigate the risk for high speed designs.