PCB视觉检测系统的研究

【作者】 孙晓婷；

【导师】 熊红云；

【作者基本信息】 中南大学 ， 模式识别与智能系统， 2008， 硕士

【摘要】 在现代电子设备中,印刷电路板(PCB)发挥着越来越重要的作用,其质量的好坏在一定程度上决定了电子产品的性能。因此,对印刷电路板进行缺陷检测在工业生产中具有极其重要的应用价值。为了实现PCB生产过程中的缺陷检测自动化,本文应用虚拟仪器及其机器视觉技术,开发了一种PCB视觉检测系统。论文从图像处理和模式识别的角度出发,研究了不同PCB缺陷的特点,在总结前人所用的PCB缺陷识别方法的基础上,综合各自优点,提出了基于图像识别的PCB检测方法。为了提高印刷电路板数字图像的信噪比,采用了直方图均衡化、中值滤波等预处理算法优化图像质量;在电路板缺陷识别与检测方面,对元件丢失和元件极性反装,提出模板匹配算法,实现了印刷电路板图像与模板图像之间的快速对准与参考比较;对焊点缺陷,提出应用数学形态学处理方法提取焊点的特征,然后根据特征判别是否为缺陷焊点;对PCB短路、断路的缺陷,提出基于边缘检测法来识别方法。论文应用NI公司的虚拟仪器软件LabVIEW及图像处理工具包IMAQ Vision进行PCB视觉检测系统开发,实现了图像采集,光板检测,元件匹配检测,表面焊点检测,检测结果分析等功能。该系统操作简单,界面友好,可靠性高。更多还原

【Abstract】 Nowadays, Printed Circuit Board (PCB) plays an important role in electronic devices. The quality of electronic productions somewhat depends on that of Printed Circuit Board. Due to the fatigue, subjectivity and speed requirement, manual inspection is ineffective to inspect every complex board. To realize defect inspection autom atically, some vision detection system for the PCB by Virtual Instrument and computer vision are studied in this article.This paper proposes a new method for automatic component detection by computer. Based on digital image processing, we have studied different features of the PCB defection . In order to identify the disfiguration, we colligate advantages of some other Image identify methods and develop a way belonged to this thesis which based on image recognition technology. Some image preprocesses algorithms such as Histogram equalization, Median Filter are used for enhancing the SNR (Signal Noise Ratio) of the PCB image. In the procedure of defect detection and identification, a series of digital image processing algorithms are adopted to detect the lost and polarity fault of components by the way of Template Matching Algorithm. This process achieve the fast alignment and reference comparison between the PCB image with the template image. In a case of solder inspection, Mathematical Morphology is used to extract features of solder joints and judge whether there is solder joint or not. At last,to detect the fault of short Circuit and open circuit, Edge detecting Algorithm is used.In this paper,the software development adopts the NI Company’s Virtual Instrument Labview and vision took it IMAQ Vision. The software realizes the function of complete detecting, image collection, image pre-process, the fault inspection of bared PCB, component matching inspection and solder joint inspection. It has the merit of easily operation, friendly interface, high reliability and so on.更多还原