Use these drills after completing all topics in MBIST & LBIST. Answer with metric, mechanism, evidence, owner, and regression plan.
[INT][DFT][MBIST-LBIST]
Q: Why can MBIST pass but yield remain poor?
A:
Repair programming, diagnosis mapping, or production flow integration can be broken despite clean insertion.
FOLLOW-UP TRAP: Assuming MBIST insertion equals yield closure.[INT][DFT][MBIST-LBIST]
Q: What is a common LBIST signoff pitfall?
A:
Ignoring random-pattern-resistant faults and overclaiming quality from signature checks alone.
FOLLOW-UP TRAP: Treating LBIST as a full ATPG substitute.METRIC -> MECHANISM -> EVIDENCE -> FIX -> REGRESSIONBIST FLOW
insert MBIST/LBIST -> execute -> collect signatures -> diagnose/repair -> signoffState metric, lot/corner context, and pattern tag with every claim.
Treat timing, power, and quality as one signoff problem.
Chasing coverage without legality checks.
Ignoring test-power side effects of pattern changes.
Debugging silicon without reproducible tags.