LRT-DETR: An Enhanced Transformer-Based Framework for PCB Surface Defect Detection

To address the issues of complex background interference and micro-defect detection in printed circuit board (PCB) surface inspection, while accommodating the deployment constraints of edge devices in industrial scenarios, this paper proposes a lightweight real-time detection Transformer (LRTDETR), an improved architecture based on RT-DETR. First, the original ResNet18 backbone is replaced with RepNCSPELAN, a lightweight network leveraging structural re-parameterization to reduce model complexity. Second, a global-local bidirectional feature pyramid network is introduced in the neck, which enhances the multi-scale feature representation through an adaptive weighted feature fusion mechanism, significantly improving small defect detection. Experimental results demonstrate that the improved model achieves a 96.9% mean average precision (mAP) with only a 0.2% performance drop compared to the baseline. Notably, the model size, the parameters, and the FLOPs are reduced by <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$58.3 \%, 53.5 \%$</tex>, and 57.3%, respectively. The inference speed reaches 39 FPS, balancing accuracy and efficiency for real-time industrial inspection and edge deployment. This work provides a practical solution for highprecision, resource-efficient defect detection in industrial edge computing environments.