What is the Printed circuit board annular ring spec?
Minimum Annular Ring; PWB Internal Via
Both diagrams indicate minimum annular ring measured from the outside ring of the pad and to the inside diameter of the plated thru-hole for an external pad [below], or to the center of the plated via for an internal pad [above].
Minimum Annular Ring; PWB External Pad
Minimum Annular Ring applies regardless of the shape of the PCB pad. The next page shows two examples of different pad shapes.
More Printed Wiring Board Terms