Annular Ring
In plain English
The little ring of copper around a drilled hole. If it's too thin, the drill can break out of the pad and ruin the connection — like a hole punched too close to the paper's edge.
The technical version
The ring of copper surrounding a drilled hole in a pad.
The annular ring is the copper collar left around a drilled hole after fabrication. Insufficient ring, combined with layer-to-layer misregistration, causes drill breakout where the hole exits the pad. IPC Class 3 requires a larger minimum annular ring than Class 2 for higher reliability.
Related terms
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