Printed circuit board film is used for making PCB. Size and defects are important parameters in PCB films' quality
evaluation. An online measuring method based on linear CCD for 500mm width PCB film was proposed. The method
included (1) definition of parameters, (2) imaging range, which was wider than a PCB film unit to reduce the errors
coming from the assembling of CCD and (3) the 2D scanning of PCB film and CCD. Template matching was used for
extracting the interested region. Region growing was used for pinhole detection. Image subtraction was used in breakage
detection. And region segmentation was used for size measurement. According to the design and analysis, the online
measuring method can meet the demands. Experiments showed that (1) the method can detect and classify PCB films'
defects efficiently, and (2) the size measuring accuracy can reach 0.1mm.