Technical Articles From National Cheng Kung University
Read technical articles about electronics manufacturing added by National Cheng Kung University
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2 technical articles added by National Cheng Kung University
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A Machine Vision Based Automatic Optical Inspection System for Measuring Drilling Quality of Printed Circuit Boards
Apr 29, 2024 | Wei-Chien Wang, Liang-Bi Chen,Wan-Jung Chang, Shang-Liang Chen, and Katherine Shu-Min Li
In this paper, we develop and put into practice an Automatic Optical Inspection (AOI) system based on machine vision to check the holes on a printed circuit board (PCB). We incorporate the hardware and software. For the hardware part, we combine a PC, the three-axis positioning system, a lighting device and CCD cameras. For the software part, we utilize image registration, image segmentation, drill numbering, drill contrast, and defect displays to achieve this system. Results indicated that an accuracy of 5µm could be achieved in errors of the PCB holes allowing comparisons to be made. This is significant in inspecting the missing, the multi-hole and the incorrect location of the holes. However, previous work only focusses on one or other feature of the holes. Our research is able to assess multiple features: missing holes, incorrectly located holes and excessive holes. Equally, our results could be displayed as a bar chart and target plot. This has not been achieved before. These displays help users analyze the causes of errors and immediately correct the problems. Additionally, this AOI system is valuable for checking a large number of holes and finding out the defective ones on a PCB. Meanwhile, we apply a 0.1mm image resolution which is better than others used in industry. We set a detecting standard based on 2mm diameter of circles to diagnose the quality of the holes within 10 seconds....
Design and Experiment of a Moving Magnet Actuator Based Jetting Dispenser
Jan 13, 2021 | Minh-Sang Tran and Sheng-Jye Hwang
Developing actuators to drive high-frequency jetting dispensers in the dispensing technology for electronic assembly applications has become a concern in recent years. This study proposed a new jetting dispenser without a displacement amplification mechanism directly actuated by a moving magnet actuator (MMA) to jet small fluid droplets. In this article, the main geometric dimensions of ......
