| 摘要 |
PURPOSE:To accurately inspect abnormality of a circuit on a circuit board by placing a detection coil at specific distance from the cirucuit board, supplying a high frequency current thereto, and measuring a high frequency current which flows through the detection coil owing to an eddy current generated in the conductor of the circuit board. CONSTITUTION:The circuit board 1 is placed on a plane 2 and the detection coil 4 of a measuring instrument 3 is provided at constant height and supplied with the high frequency current. Consequently, a current (eddy current) is gener ated in a circuit 5 on the circuit board 1 by a high frequency magnetic field. This eddy current is different according to the patterns of circuits on the circuit 5 and the high frequency current which flows through the detection coil 4 is also different. For the purpose, the high frequency current is converted into a DC voltage as to a circuit board with a standard pattern and variation in the voltage is recorded on a recorder 6; and the voltage variation of the inspected circuit board is compared with that of the circuit board with the standard pattern to decide abnormality of the circuit board such as a short- circuit and the breaking of wire.
|
