ECT応用を目指したSV-GMRセンサの高周波数微小磁界振幅特性(計測・高周波デバイス)

概要

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The eddy-current testing technique is an interesting method for detecting defects on bare printed circuit boards. This technique detects various defects without mechanical stress to PCB patterns. Usually various pickup coils are used in an ECT probe as a magnetic sensor. Pickup coil sensors, however, do not show enough S/N ratio to detect defects in high-density PCBs, whose conductors are less than 100 μm. We propose a new ECT probe with a spin-valve giant magnetoresistive (SV-GMR) sensor for inspection of PCBs. SV-GMR sensors show high sensitivity to a small magnetic field in one direction. This sensor senses a magnetic field as varying its resistance unlike inductive sensors such as a pickup coil. In this paper, we investigated the sensing properties of a SV-GMR sensor with changing axes, frequencies, and magnetic field amplitudes, and discussed problems that could occur in replacing a pickup coil with SV-GMR.
社団法人日本磁気学会の論文
2004-03-01