Issue link: https://resources.pcb.cadence.com/i/1180264
Working with Backdrilling Backdrilling October 2019 13 Product Version 17.4-2019 © 1999-2020 All Rights Reserved. Figure 1-3 Calculating Stub Value Pin Plating Restrictions The manufacturer of a connector may specify a minimum plating depth from the mounting side to ensure its pins are fastened to the PCB properly. If pins on a connector with this restriction are to be backdrilled, the minimum pin plating depth would take precedence over resolving the stub violation. For example, a trace connects two pins on LAYER_2. An electrical stub is present from the BOTTOM layer up to the surface of LAYER_2 because there is no other connections made below LAYER_2. Backdrilling from the bottom side of the PCB, removes the stub by drilling beyond LAYER_3 and stopping in the dielectric material before hitting LAYER_2 to meet the electrical stub requirements. Doing this violates the manufacturing minimum plating depth requirement and the connector pin is no longer have a reliable connection to the plated through-hole.