DFT / ATPG · All levels

DFT Physical Integration: Tricky Q&A

Senior interview and review questions for DFT Physical Integration.

Section Q&A bank

Use these drills after completing all topics in DFT Physical Integration. Answer with metric, mechanism, evidence, owner, and regression plan.

What is the most expensive late DFT physical mistake?

diagram

[INT][DFT][DFT-PHYSICAL-INTEGRATION]

Q: What is the most expensive late DFT physical mistake?

A:
Poor chain order/floorplan assumptions that require large-scale reroute and hold repair near signoff.

FOLLOW-UP TRAP: Treating chain ordering as a post-route cleanup item.

How do you reduce DFT-PD churn?

diagram

[INT][DFT][DFT-PHYSICAL-INTEGRATION]

Q: How do you reduce DFT-PD churn?

A:
Versioned handoff contracts for chain rules, test clocks, placement legality, and ownership.

FOLLOW-UP TRAP: Relying on verbal agreements only.

Q&A drill guide

diagram

METRIC -> MECHANISM -> EVIDENCE -> FIX -> REGRESSION

Sketch while answering

diagram

PHYSICAL DFT FLOW

chain planning -> floorplan placement -> route -> test timing/power validation

Key takeaways

State metric, lot/corner context, and pattern tag with every claim.
Treat timing, power, and quality as one signoff problem.

Common pitfalls

Chasing coverage without legality checks.
Ignoring test-power side effects of pattern changes.
Debugging silicon without reproducible tags.

Practice this lesson