| 摘要 |
PURPOSE:To determine the formation position of a previously set through hole accurately without destruction by impressing a magnetic field crossing the surface of a multilayered printed board at right angles, and detecting the phase inversion of alternating magnetic flux at a guide cut formed in the board at its peripheral edge. CONSTITUTION:The magnetic field crossing the surface of the multilayered printed board is impressed by a coil 7, and a magnetic head 8 is arranged as a magnetic flux detecting means on the surface side of the board. At this time, the alternating magnetic field is inverted in phase at an end surface of the metallic field is inverted in phase at an end surface of the metallic core material of the guide cut part formed in the board. Then, an X and a Y motor are driven and when the output of the head 8 is larger than a specific value, a level decision pat 10 inputs a detection signal to a phase difference detection part 11 to detect the phase difference from the output of an oscillation part 12. When the phase difference is <=180 deg., it is judged that the head is positioned in the center of the guide cut, and a driving decision part 13 outputs a motor stop signal to X and Y motor driving control parts 14 and 15. Consequently, the position of the previously set through hole is determined accurately on the basis of the positions of the guide cuts provided at two positions and the influence of leak magnetic flux is less than a method which detects the passing magnetic flux of the board.
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