define annular ring
When traces on a circuit board need to connect to another layer, they typically end up on a pad and then through a via on that pad go to connect to another layer. An annular ring is the area on the pad that surrounds the via. An Annular Ring Width is the (diameter of the pad-diameter of the hole) / 2. (Tangency is the default option, and the DFM will check for 5 Mils minimum annular ring width). (NOTE: accepting Breakouts is typically NOT recommended!).