A 3D inspection system for PCB board by fusing moiré technique and stereo vision algorithm

Automatic PCB (printed circuit board) assembly technique plays a very important roll in modern industry where electronics is becoming an indispensable part. Each process of assembly requires well-developed inspection technique to ensure quality of the products and prevent waste of resources. In the case of chip mounting inspection, a number of 2D inspection techniques have been developed but there are challenging problems still remaining. In this paper, a 3D measurement method based on phase shifting and stereo vision for inspection of chip mounting is proposed. The hardware system and algorithm that employ the proposed methods are developed and are described in detail. The results show that height measurement of the chip-mounted board can be achieved with satisfactory accuracy.