Development of an Appearance Defect Inspection System for Flexible Printed Circuit Board
In recent years,flexible printed circuit boards (FPC) have been widely used in consumer electronic products.Pads on the FPC are designed as contact ports to transmit electrical signals with other components.Usually,the surface of pad is formed by gold plating process.However,the surface of final products may contain defects such as surface scratches,foreignmaterials or color variation due to machining or assembling processes.In this study,an automated optical inspection (AOI) system is developed to detect the defects on the pad.The hardware of the system is composed of a vision module and a motion module.The former includes a high resolution CMOS camera (10 mega pixels) and a coaxial light.The latter is a twodimensional moving platform with positioning error less than 1μm.The proposed software consists of two functions,template training and defect detection.During the training process,operators need to position golden samples on the platform and to specify the locations of pads on the FPC image.The system will automatically determine regions of interest and collect necessary information from the image by using magic-wand method.Next,statistic data abstracted from the pad images are used to define color thresholds of RGB planes and to extract the pad particles.Later,sample products can be put on the inspection stage successively and defected instances will be identified based on the parameters obtained from the training process.In order to examine the performance of the proto-type machine,more than 7500 pads on 10 strips of FPC are inspected and both the underkilled rate and the over-killed rate are both less than 4%.
automated optical inspection flexible printed circuit boards pad defect inspection
Chih-Hsien Su Shui-Fa Chuang Chieh-Kai Chan Geo-Ry Tang Fang-Jung Shiou
Department of Mechanical Engineering, National Taiwan University of Science and Technology, Taipei, Opto-Mechatronics Technology Center, National Taiwan University of Science and Technology, Taipei, T
国际会议
天津
英文
130-134
2012-10-16（万方平台首次上网日期，不代表论文的发表时间）