Research And Implementation The PCB Defect Automatic Optical Inspection System Based On The Image Processing

Along with the developing of communications and electronical technicals, the printed circuit board are also quickly developed. In order to assure the quality of our circuit board, we need to accomplish its quality tests before the system assemble line-work, considering the abundance of the industrial manufacture, we need to have effective methods according to different period in manufacture to ensure circuit board's quality.In this paper,it was explored how to utilize Automated Optical Inspection technology to inspect PCB based on the technology of image process.Automated Optical Inspection system acquires the images of the PCB,and the images are analyzed to determine whether there are any defects in the board by digital image processing.And the information will be transmitted in time to correct the production parameters.This is a lossless and fast system,which is used to inspect welding spots'defect,thus it is helpful to reduce the production cost,improve the product quality and the production efficiency.Totally speaking,the thesis includes the following parts:(1)Compared with other methods which are used for inspecting defects, analyse the structure of Automated Optical Inspection system and the main technical difficulties.(2)Analyse the characteristics of the PCB images.Because of dissatisfactory image,such as low-contrast which is caussed by the entironment lighting,disturbed by the noise and so on.Using a series of image pretreatment methods to improve the contrast of image,restrain noise disturbance and get a sharp image.(3)Considering between the detection and standard images may exist the misalignment problems, compare the Hough transform, templates, and the image registration based on the characters, completed the alignment between the test and standards images;(4)Using a series of digital image processing,complete the PCB segmentation and difference image detection for PCB image extraction and differential in defects.(5)Design the AOI system and used in the actual production line.Analyse the result,it is helpful to reduce the production cost,improve the product quality and the production efficiency.