PCBA · AOI GUIDES
Guides organised by board defects, imaging conditions and acceptance methods, with inspection kept distinct from robot handling.
2D and 3D AOI inspect optically visible appearance, placement and surface height. Solder joints hidden beneath packages, internal solder voids and concealed bridges require a suitable X-ray, AXI or CT inspection method. Optical 3D reconstruction cannot see through a package. A visible QFN side fillet does not establish the condition of its underside pad.
→Post-reflow AOI checks visible solder bridges, insufficient solder, displaced components, tombstones and lead anomalies. 2D inspection evaluates appearance; 3D adds surface-height measurements. Surface images alone cannot certify internal joint structure, wetting or electrical connectivity.
→Component inspection covers presence, placement, orientation, visible markings and body damage. Polarity decisions need a visible mark or geometric feature. Parts with identical appearance and markings cannot be distinguished by electrical value using AOI alone.
→3D AOI measures visible surface heights to assess lifted leads, raised components and relative coplanarity. Results depend on the reference plane, reflectivity, occlusion and calibration. A picking pose from a robot camera is a different output from an AOI defect decision.
→Gold-finger inspection targets visible scratches, foreign material, contamination and unusual colour. Directional reflections from plating require controlled lighting, viewing angles and board positioning. Colour changes can flag review but do not establish plating composition or contact resistance.
→OCR reads visible characters, OCV compares them with expected text, and code reading supports board and lot traceability. Missing, blurred, shifted and low-contrast markings must be evaluated with actual fonts, illumination and resolution.
→Provide board dimensions, component heights, target defects, cycle time and inline or offline requirements. We evaluate visibility, imaging and acceptance criteria with your production samples.
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