AQL Sampling Plans for Electronics Inspection
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Sampling is how a QC inspector decides whether to accept or reject a production lot without checking every unit. For electronics from China, the standard is ANSI/ASQ Z1.4 (formerly MIL-STD-105E): for a 3,000-unit lot at General Inspection Level II, the plan pulls 125 pieces and, at AQL 2.5 for major defects, rejects the lot at 8 or more majors. Getting the sample size and AQL level agreed in writing before the inspection date is what prevents disputes at the factory gate.
When you actually source, sampling tells you the inspection scope, not perfection — a passed lot can still carry defects below the AQL threshold. The common pitfall is accepting a factory's offer to 'inspect 100%' verbally; without a defined sample size, defect classification, and AQL per Z1.4, pass/fail is unverifiable.
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FAQ
How many units get sampled in a typical China inspection?
It depends on lot size and inspection level. Under ANSI/ASQ Z1.4 General Level II, a 1,200-unit lot samples 80 pieces and a 10,000-unit lot samples 200. Lower levels (S-1 to S-4) sample fewer units for destructive or expensive tests.
What AQL should I set for electronics?
Common practice is AQL 0 for critical (safety) defects, 2.5 for major, and 4.0 for minor. Tighten the major AQL to 1.0 or 1.5 for products where field failures are costly, like wearables or chargers.
Can a lot pass inspection and still have defects?
Yes. AQL sampling accepts a small, defined percentage of defects. If you need near-zero defects, specify 100% inspection or screening (e.g., burn-in testing) in addition to AQL sampling.
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