Lighting Geometry
Optical inspection lighting configurations combine multiple LED ring lights positioned at distinct angles relative to the printed circuit board surface to highlight solder joint contours and component package details. The optical methodology designated as multi-angle illumination projects low-angle grazing light, mid-angle oblique light, and high-angle coaxial light onto target solder joints during automated optical inspection. Varying light angles reveals surface curvature, solder fillet shapes, and lifted component leads that single-source illumination misses.
This lighting system applies strictly to automated optical inspection and solder paste inspection equipment used in surface-mount manufacturing. It stops applying during x-ray inspection, which relies on penetrating radiographical transmission rather than reflected visible light spectrums.
Defect Detection
Solder fillets reflect light differently depending on surface angle and wetting quality during optical evaluation. Applying multi-angle illumination enables inspection algorithms to differentiate between flat copper pads, curved solder fillets, and shiny component terminations. Low-angle red light highlights solder meniscus edges, while high-angle blue light lights flat top surfaces of ceramic chip capacitors.
Combining these light channels creates color-coded topography maps in machine vision software, identifying solder bridging, insufficient solder, and component lead lifting accurately. Precise lighting control prevents false call defect flags.
Optical Boundary
Highly reflective component bodies and specular solder surfaces can produce glare that saturates vision system sensors. Proper calibration of individual ring light intensities prevents optical saturation on shiny quad flat package leads. Correct light setup ensures repeatable automated inspection.
