Rule category: High Speed
Rule classification: Unary
A stub is the length of via or pad barrel that protrudes beyond the last-used signal layer that the via/pad connects on. Back drilling will be applied to suitable vias/pads in nets targeted by this rule, in accordance with the enabled side-of-board Layer checkboxes, and the back drill [BD] pairs defined in the Drill-Pair Manager dialog.
As well as being used to define which vias/pads are to be considered for back drilling, during design rule checking this rule tests for via and pad stubs longer than the specified Max Stub Length, for all nets targeted by this rule (regardless of whether back drilling has been applied to that via or pad). This rule also specifies how much larger the drill size must be for vias and pads that are back drilled.
All rules are resolved by the priority setting. The system goes through the rules from highest to lowest priority and picks the first one whose scope expression matches the object(s) being checked.