Patent attributes
A detection unit 1 for detecting an electric field or a magnetic field is placed above a circuit board 4 to be detected. A control device 3 allows the detection unit 4 to carry out detection processes while moving the detection unit 1 in a predetermined direction with an electric current being applied to the circuit board 4 so that an electric field distribution or a magnetic field distribution on the circuit board 4 is detected. Moreover, the control device 3 compares the results of the detection with reference data that has been preliminarily registered, and if there is any portion between the two pieces of data that is not coincident with each other, it is determined that the corresponding circuit board 4 is a defective circuit board. Thus, it is possible to detect any defective portion on the printed circuit board with high precision in a non-contact state to the circuit board.
