✓ Design for manufacturing
Can the product be made with existing equipment, processes, and skills?
✓ Process stability
10 samples work, but >98% yield at 1,000 units?
✓ Lock mass production baseline
Finalize BOM, SOP, test standards, labor quotas → make MP “foolproof & standardized”.
EVT
Engineering Verification Test
Purpose: verify basic function, circuit design, mechanical fit.
Quantity: usually a few to dozens of units.
Focus: can the board power on? Screws tighten correctly? Button feel? Design often changes; hand modifications and flying wires may occur.
Assembly work: provide DFM feedback — e.g., "capacitor too close to screw boss, will collide in mass production", "clip design prone to breakage".
DVT
Design Verification Test
Purpose: verify design completeness. Tooling is typically T0 (first trial), structural parts from trial molds.
Quantity: dozens to hundreds of units.
Focus: system functionality, reliability (thermal shock, drop, waterproof), thermal management, EMC compliance.
Assembly work: fixture development. Assembly jigs (press jigs, dispensing fixtures) and test fixtures (bed-of-nails, functional testers) are designed and validated.
PVT
Production Verification Test
Purpose: validate mass production capability. This is the most critical NPI phase — produce using "mass production status".
Quantity: typically 10–20% of the initial batch volume, or several hundred to thousand units.
Use production fixtures and processes: no manual workarounds, fully automated or semi-automated lines.
Ramp‑up validation: test line takt time, verify daily output targets.
Yield monitoring: record defect rate at each station, analyze top issues (e.g., "screw cross‑threading accounts for 30% of defects") and resolve before MP.
Line ramp‑up, cycle time verification, yield monitoring → fix top issues before MP.
MP
Mass Production
After PVT validation and yield targets are met, formal mass production begins.
Stable output, sustained quality control.
Full‑scale production with validated processes and fixtures.
