Automated Eddy Current Monitoring of Thin Metallic Films for Resource-Efficient Manufacturing and Waste Prevention

Defects in thin metallic films may remain undetected until later manufacturing steps have already consumed additional materials and energy. This study developed and experimentally evaluated an automated non-contact eddy current platform for local quality monitoring of thin metallic films. The system combines a miniaturized high-frequency transformer-type probe with a conical ferrite core, three-axis positioning, digital acquisition, and Python (v3.14)-based processing. Cu and Ni films 100–800 nm thick were tested. Across 4–25 MHz, 25 MHz produced the highest signal-to-background ratio. Finite element modeling showed that the ferrite core increased peak eddy current density in the film by more than a factor of two. Two artificial defects measuring 6.2 × 0.11 mm and 4.5 × 0.17 mm were localized; signal gradient analysis reduced length estimation errors to 1.6–6.7%, compared with 6.4–17.8% for direct amplitude analysis. Eddy current spatial profiles agreed with independent photometric measurements (R2 = 0.89). A separate scenario-based engineering assessment examined potential resource savings from post-deposition inspection. Early detection can prevent unnecessary downstream processing of defective substrates, supporting waste prevention and resource efficiency. The sustainability values reported here are scenario estimates rather than direct industrial measurements.