First establish that the required joints can be observed on the actual SMT assembly, then validate AOI criteria. Busbar walls, tall standoffs and neighboring parts can limit visibility; reflections can affect measurement. Identify unobservable regions explicitly rather than accepting them because no alarm occurred.
Map visible and hidden regions on the assembly
OMRON's technical paper explains that electrode/pad geometry affects solder shape and that shadows and secondary reflections interfere with optical measurement. We recommend mapping target fillets, hardware height and neighboring components, distinguishing visible sides, partial obstruction and fully hidden connections.
Retain actual images for the selected equipment, lighting and viewing directions. Review visibility again after hardware orientation, neighboring height or board revisions change. Separate unable-to-measure records from measured-and-rejected results.
Validate the program with independently classified samples
Prepare representative samples classified through independent evidence, covering placement, missing parts and relevant solder defects. Retain accepted/rejected images, classification basis, program revision and review results, identifying defects not covered by validation.
Document sample counts and defect categories when evaluating false calls and misses. Do not transfer a vendor paper's improvement percentages into site detection-rate claims. After relaxing thresholds to reduce reflective false calls, recheck known defective samples as well as accepted boards.
Assign suitable supplementary inspection to hidden joints
OMRON separately discusses visually inaccessible solder and CT X-ray inspection. Have process and quality owners select appropriate X-ray, sectioning or other validation for hardware-bottom connections and confirm the questions each method can answer. Multi-view AOI still needs proof of actual visibility.
Record uncovered regions, supplementary methods and sampling. Appearance alone does not establish bond strength or current capacity; verify those separately. Review design or validation when critical joints remain without an effective inspection basis, instead of treating blank areas as accepted.
- Prove visibility using populated-board images
- Retain program and classified samples
- Validate hidden connections independently
Frequently asked questions
Does 3D AOI cover every bottom joint? Verify viewing access and obstructions; hidden joints are not automatically covered.
Do all-pass boards demonstrate no missed defects? Use confirmed defective samples and independent review to evaluate detection.
RFQ and DFM inspection inputs
Provide hardware and pad drawings, orientation, neighboring heights and target defects. Agree visibility validation, program revision and supplementary inspection ownership. Confirm supplied geometry separately from the assembler's program, without promising an untested universal detection rate.
Apply this guide to a project
Use product pages to identify the hardware family and the calculator for early estimates only. Acceptance depends on drawings, operating conditions and project tests.