AOI Review: Separate an Inspection Call from a Confirmed Defect

Author : HUANG Micky | Published On : 06 Nov 2026

An automated optical inspection (AOI) call identifies a feature that needs review. It is not automatically a confirmed assembly defect. Treating those two states as equivalent makes process feedback less useful.

First, review the feature against the released assembly drawing and agreed acceptance criteria. Record the reference designator, package, image and decision. Where the image cannot establish acceptability, use the approved secondary inspection method rather than guessing.

Next, classify the result. A confirmed defect needs containment and investigation of its cause. A false call needs investigation of the inspection setup. Lighting, reference images, component appearance and board positioning can influence image interpretation; changing an acceptance threshold is not a substitute for understanding the evidence.

Keep program changes traceable. Record what changed, why it changed and which board revision it applies to. Recheck representative known conditions before release. A lower alarm count alone does not demonstrate improved detection: it may also mean a real defect is no longer being flagged.

Track reviewed calls and confirmed defects separately, with clear denominators. Use recurring patterns to direct investigation into assembly or inspection conditions. Preserve the original evidence before rework so the cause can be investigated.

For context, this PCB assembly overview lists inspection and test methods within a production scope: PCB assembly service scope

The actual coverage, review procedure and reporting still need project-specific agreement. AOI does not replace testing of electrical functions that its images cannot establish.