Automated Optical Inspection Technology For Pcb Surface Defects

The industry of Printed Circuit Board(PCB) is quickly developing along with the rapid development of the communications,computer and electron industry. Now PCB has been an important part ofthe modern electronic products world.The quality of PCB will lead mortal influence to the normal work of electronic products. In face of costly inspection device overseas and intense requirements of PCB manufacture,research on a kind of rapid and useful technology of Automatic Optic Inspection(AOI) has important academic and economic value.In many PCB defect detected methods,the technology of AOI has unique advantage.This paper applies Virtual Instrument technology to PCB vision inspection based on researching AOI.We constitute the hardware part of an AOI system with the Virtual Instrument products of NI Corporation,and then we finish designing the software of the PCB inspection system with LabVIEW.During image pre-processing,we test different arithmetic of each image processing method,and compare and analyze their result after test,then choose furthest excellent arithmetic adapting to PCB defect detection.Plenitude bring into play the dominance of the image processing function in IMAQ VISION,colligate large numbers of arithmetic and user define rithmetic operators,so we can rapid realize programme and meet the need of images definition,thus establish the base for image recognition.Image locating of PCB is largely influenced the automatic detection about PCB defection. The author Used pattern matching techniques to establish the coordinate system in the image of the PCB.Then used a spoke to find points on a circular edge,and then fited a circle on the detected points.Brought forward three arithmetic about the angle orientation of the detected PCB image and analyzed their dissimilarity.With theoretical analysis and experiments,the measure of spoke is efficiency.About PCB image recognition,this paper bring forward two recognition methods.One can rapid recognize five defect of PCB through Particle Analysis Report.Vi which reduce the flow of procedure.The inspection speed is more rapid and programme realization is easier.Another is accomplishment the defect inspectioin by comparison operation and pesudocoloring which enhance sensibility cognition about defect.It belong to half automatic inspection which capability is much more excellent than manual inspection in precision and speed.Experimental results demonstrate that short circuit, open circuit, protuberance and concavity on PCB and so on defects can be effectively detected, located and recognized through the detection system.