摘要 |
A magnetic field applying portion is positioned above a magnetic field applied region, and applies a magnetic field to the magnetic field applied region. Among probes which are abutted against ball grids of wirings, two probes are selectively connected electrically to a current detector section whereby a closed circuit is formed. This causes the closed circuit to carry an induced current as the magnetic flux through the magnetic field the magnetic field applied region changes with time. A current detector of the current detector section detects the value of the induced current, and whether there is a short-circuit is judged based on the detected current value.
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