Phase gate guide
EVT, DVT, PVT — what each build is actually for
Three validation builds sit between a working prototype and mass production. Most definitions online tell you what the letters stand for. What matters on a real program is the question each build answers, what has to be true to exit it, and what it costs you when you pass a gate you should not have.
EVT — Engineering Validation Test
Does the design work at all?
Tens of units, often built by hand or on a partially tooled line.
Prove the architecture. Power up the board, confirm the major subsystems function together, and find the design errors that only show up in physical hardware. Expect rework, blue wires, and parts that are not yet from the final supplier.
Exit criteria
- Core functionality demonstrated on real hardware
- Critical design issues identified with owners and fix dates
- Schematic and layout changes captured under change control
- Preliminary BOM with long-lead items identified
The common mistake
Treating EVT as a demo. If nothing failed at EVT, you did not test hard enough — you just moved the failures downstream where they cost weeks instead of hours.
DVT — Design Validation Test
Does the design meet every requirement, every time?
Hundreds of units, built on production-intent tooling.
Freeze the design and prove it against the full specification: thermal, mechanical, EMC, regulatory, drop, reliability, and environmental testing. Parts should come from qualified suppliers on production tooling, not machined mock-ups.
Exit criteria
- Design frozen; all changes go through formal change control
- Regulatory and reliability test plans executed with results documented
- Production tooling qualified and first-article inspections passed
- BOM fully sourced with alternates identified for high-risk parts
- Test coverage and fixtures defined for the factory line
The common mistake
Carrying open design changes into DVT. A change at DVT invalidates tooling, retests, and certifications — the cost is measured in weeks, not hours.
PVT — Production Validation Test
Can the factory build it, repeatably, at volume and at yield?
Thousands of units, built by factory operators on the real line.
Validate the process, not the design. The line runs at planned takt time with production operators, production fixtures, and production documentation. You are measuring yield, cycle time, test escape rate, and operator error — not whether the product works.
Exit criteria
- Yield at or above the mass production target with a documented trend
- Line balanced at planned takt time with trained operators
- Work instructions, test scripts, and quality gates released and followed
- Open defects closed or dispositioned through 8D with root cause
- Supplier capacity confirmed against the ramp forecast
The common mistake
Letting engineers touch the units. If your team is standing on the line fixing builds, you are measuring your engineers, not your factory.
How to run the gate itself
A gate is a decision, not a date
The gate exists to answer one question: do we commit the next tranche of money and tooling? If the exit criteria are not met, passing the gate anyway does not save schedule — it moves the failure to a more expensive phase.
Exit criteria are written before the build
Agree what 'done' means with engineering, quality, and the CM before the first unit is built. Criteria negotiated after a failed build are always negotiated downward.
Supplier readiness is part of the gate
Tooling qualification, first-article inspection, and capacity commitments belong in the gate review. A design that passes DVT with a supplier who cannot ramp is not ready.
Every phase has a build plan and a lessons-learned
Quantities, allocation of units to test groups, shipping logistics, and who owns each failure. Then a written retro before the next build kicks off.
The full framework is in the book
The Hardware NPI Playbook covers the phase gate model end to end, plus contract manufacturer selection, supplier qualification, and root cause failure analysis — with gate review and build readiness checklists you can use on your current program.
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