Test (fault) coverage
Beginner
The share of possible manufacturing flaws that the factory tests can catch.
Novice
The percentage of possible manufacturing flaws, modeled as simple faults such as a wire stuck at 0 or stuck at 1, that the factory’s test patterns would detect. Higher coverage means fewer bad chips slip through.
Expert
Set at the spec stage from the outgoing-quality target, because the fraction of bad chips that escape depends on both yield and coverage. Targets for stuck-at faults (a node stuck at 0 or 1) and transition faults (a node too slow to switch) drive the scan test circuitry, extra test points, built-in memory self-test and tester time, so they belong in the requirements.