Standardized Calibration Sequences for Fine Pitch Optical Inspection Engines
Standardized optical calibration using certified glass targets and phase step standards ensures micron-level accuracy across fine pitch inspection runs.
Structured Light Profilometry
Volumetric Profiling
An optical measurement method uses the deformation of projected light patterns to calculate the three dimensional shape of circuit board features. Surface mount assembly lines rely on structured light profilometry to measure the height, area, and volume of deposited solder paste bricks. This technique provides faster and more accurate height maps than point by point laser scanning.
It is used in both solder paste inspection and automated optical inspection systems.
Optical Scanning
Projecting a series of light fringes onto the circuit board surface creates a distorted pattern that varies with the surface height. In structured light profilometry, a projector casts light grids while a camera captures the resulting image from a different angle. The software calculates the phase shift of the light lines to reconstruct the height of each pixel across the board surface.
Multiple projector designs are often used to eliminate shadow effects caused by tall adjacent components or high paste deposits. This multi direction illumination allows the system to measure complex solder joint shapes on fine pitch ball grid array sites. This reconstruction is executed in milliseconds to match the speed of the assembly conveyor.
Quality Inspection
Three dimensional height profiling is necessary to detect coplanarity defects in mounted chips and insufficient solder joints. The height data allows the system to verify that leaded components are fully seated in the solder paste before reflow. This early detection is the most cost effective way to manage assembly defects on the shop floor.
It prevents the need for complex rework after the board is soldered.