Optical Quality Verification
High-speed cameras and software algorithms are used to detect defects in printed circuit board assemblies by comparing them to a known good sample. High-resolution imagery provides a way to verify component presence and orientation without physical contact. Reliable aoi inspection identifies solder bridges and missing parts before the product reaches the testing phase.
Detection Capability
The performance of aoi inspection relies on lighting angles and image processing thresholds to distinguish between a healthy solder joint and a bridge. Shadowing from tall components or reflective glare can cause false calls that require secondary manual review. Proper calibration involves gold boards with known defects to ensure the sensor distinguishes a bridge from a shadow.
Variations in board finish or solder paste chemistry alter the light return profile. Sensitivity remains a critical variable in the precision of the scan.
Process Integration
Assembly lines typically place aoi inspection after the reflow oven to capture soldering errors before the final housing is installed. Feedback loops use these findings to adjust screen printers or pick-and-place offsets.
Standard Limit
Standard criteria found in IPC-A-610 provide the classification used to program an aoi inspection routine for class 2 or class 3 electronics. Programmable logic within the scanner assigns a pass or fail status based on these defined tolerances.
