Automatic inspection of loaded PCBs using 3D range data

Inspection of loaded printed circuit boards (PCBs) using 3D laser striping range data is described. The work presented here is intended to assess the feasibility of using 3D depth data for robust identification of PCB defects. A knowledge-based control system interrogates a 2D CAD database for PCB layout information. Test strategies are then implemented with efficient multiresolution data capture. Inspection algorithms use 3D scene models to detect and interpret faults. This paper describes the implementation of the 3D range scanner, inspection tasks, control system, and 3D scene modeling. Surface-based approaches for the inspection of 3D shape characteristics have been used extensively throughout this work. This approach utilizes the inherent 3D shape characteristics of depth data. Surface segmentation algorithms are used for the implementation of board registration, testing of components, and coplanarity of ICs.