Scholarlink

<p>Printed circuit boards (PCBs) are produced in large quantities to meet the increasing demand for diverse electronic devices. Ensuring PCB quality requires accurate and efficient defect inspection across multiple stages of the production line, from bare boards to final assembly. Manual inspection is still widely used but suffers from low efficiency and inconsistency, while automated optical inspection (AOI) faces challenges from uneven illumination, complex material surfaces, and specular reflections that degrade image quality. In this paper, we propose a tailored optical inspection system that integrates multiple lighting techniques—coaxial, polarized coaxial, and scattering illumination—combined with both monochrome and color imaging to tackle those issues in PCB defect detection. Experiments on various PCB types in a controlled laboratory setup demonstrate that the proposed system improves defect contrast and achieves at least 30&#xa0;Gy levels of contrast for 100% of legs damage and solder excess, 99.4% of component missing, 88.9% of component damage, and 88.0% of surface scratches. Moreover, the integration of a monochrome image acquisition with polarized coaxial red lighting enables consistent highlighting performance even in obscured regions, while the color imaging channel enhances coating defect identification and differentiates color areas. These findings contribute to increasing the efficiency of AOI systems and, therefore, potentially improving the quality control of PCBs in real production environments.</p> Graphical abstract <p></p>

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The optical system design to support defect detection for the automatic inspection system on printed circuit boards on the production line

  • 期刊论文

  • 发表日期：

    2026年2月28日

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  • Minh Thuan Tran,
  • Sy Hieu Dau

摘要

Printed circuit boards (PCBs) are produced in large quantities to meet the increasing demand for diverse electronic devices. Ensuring PCB quality requires accurate and efficient defect inspection across multiple stages of the production line, from bare boards to final assembly. Manual inspection is still widely used but suffers from low efficiency and inconsistency, while automated optical inspection (AOI) faces challenges from uneven illumination, complex material surfaces, and specular reflections that degrade image quality. In this paper, we propose a tailored optical inspection system that integrates multiple lighting techniques—coaxial, polarized coaxial, and scattering illumination—combined with both monochrome and color imaging to tackle those issues in PCB defect detection. Experiments on various PCB types in a controlled laboratory setup demonstrate that the proposed system improves defect contrast and achieves at least 30 Gy levels of contrast for 100% of legs damage and solder excess, 99.4% of component missing, 88.9% of component damage, and 88.0% of surface scratches. Moreover, the integration of a monochrome image acquisition with polarized coaxial red lighting enables consistent highlighting performance even in obscured regions, while the color imaging channel enhances coating defect identification and differentiates color areas. These findings contribute to increasing the efficiency of AOI systems and, therefore, potentially improving the quality control of PCBs in real production environments.

Graphical abstract