SMT007 Magazine

SMT-June2016

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82 SMT Magazine • June 2016 by Pedro M.A. Vitoriano, VISTEON, and Tito G. Amaral, POLYTECHNIC INSTITUTE OF SETÚBAL Abstract Automated optical inspection (AOI) sys- tems are commonly used in PCB manufac- turing. The use of this technology has been proven as highly efficient for process improve- ments and quality achievements. The most challenging point in inspection of surface mounting devices (SMD) is the component solder joints, due to their specular reflects. Sev- eral studies have been made to improve this situation. This paper presents an algorithm for 3D solder joint reconstruction (3D-SJR). The criteria used in the classification of the solder joints was the IPC-A-610D (Acceptability of Electronics Assemblies). Introduction One of the most common technologies used in PCB manufacturing is surface mounted tech- nology (SMT). By employing SMT, the produc- tion process speeds up, but the risk of defects also increases due to component miniaturiza- tion and denser packing of boards [1] . In these conditions, the failure detection has become critical for any SMT manufacturing process. AOI systems for PCBs have become a proven so- lution, replacing the traditional human-based inspection method [2] . Historically, the primary place for AOI sys- tems has been after solder reflow or post-pro- duction because post-reflow AOI systems can inspect for most types of defects (component placement, component polarity, solder shorts, missing solder, etc.) at one place in the manu- facturing line with one AOI system. Hence, the faulty boards are reworked before they are sent to the next process stage. Solder joint inspection has been a critical issue for quality control, mainly due to their specular reflections [3] . AOI systems have been faced with the same difficulty for solder inspec- tion [4] . In order to improve the solder joint in- spection and classification, structured light so- lutions have been used [5] . With structured light solutions, a low angle illumination ring improves the solder joint clas- sification. These light systems have proven to be a very good lighting solution for SMT inspec- 3D Solder Joint Reconstruction on SMD based on 2D Images ARTICLE

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