Detection of defective printed circuit boards using image processing

Abstract

Manufacturing of printed circuit boards involves three stages (printing, component fabrication over surface of printed circuit boards, soldering of components), where inspection at every stage is very important to improve the quality of production. Image subtraction method is widely used for finding the difference between any two images. Using this method, defects have been detected by finding the difference between reference (defect free) and test image (to be inspected). The major limitation of image subtraction is that both the images should have same size and same orientation. The proposed method removes the above explained limitation of image subtraction method and also calculates total number of defects on printed circuit boards. The proposed method is tested on six test images. The experimental results show that proposed method is simple, economical and easy to implement in small and medium scale industries where most of the inspection is still done by humans.