Non-ferromagnetic thin metal micron-sized defect detection system based on coherent accumulation-difference method

Copper and aluminum foils serve as predominant materials in fluid collectors, and defects within them can significantly impact the electrochemical performance of cells. However, existing methods for detecting defects within non-ferromagnetic thin metals, such as copper and aluminum foils, have several limitations. This study aims to address the need for detecting micrometer-scale defects on 0.1 mm copper foils, aligning with industrial field requirements. We devised an inspection device based on the induced magnetic field detection principle and explored the impact of copper foil undulations on micrometer-scale defect detection using COMSOL modeling. Subsequently, we introduced a coherent cumulative-differential algorithm to effectively mitigate the influences of circuit noise and sampling heave noise on defect signals. Consequently, the signal-to-noise ratios of 100- and 200-micron defect signals were significantly improved by 157% and 234%, respectively. This approach shows promise for detecting micrometer-scale defects in non-ferromagnetic thin metals and lays a robust foundation for future defect identification and inversion endeavors.