Design and analysis of a hybrid magnetic shielding system: application for the magnetic non-destructive testing of circuits

Abstract

Abstract A magnetic shielding system combining three-axis active magnetic shielding and a high-Tc superconducting ring (TASR) was developed. The active shield mainly responds to DC field while the ring operates for shielding AC fields below 1 kHz. In this study, the system’s shielding effects were evaluated experimentally, and the results suggest that this system can effectively shield the interference of static and low-frequency magnetic fields to ensure the operation of high-precision magnetic sensors. The shielding factor reached 99.9% for geomagnetic field (DC, 38 500 nT), which exceeded 98% for about 10 000 nT AC magnetic field at 30–1000 Hz. Then, magnetic non-destructive testing of the circuit was performed in this TASR shielding system. The images clearly showed the magnetic field distribution in different kinds of circuits that could be inverted to current density information, indicating that the shielding system can detect circuit defects and has great application potential in integrated circuit diagnosis.