Method and apparatus for inspecting printed circuit boards
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Abstract
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.
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Citations
12 Claims
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1. (canceled)
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2. A method for inspecting a printed circuit board comprising the steps of:
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applying a magnetic field onto said printed circuit board using a magnetic field inducing structure without physically contacting the printed circuit board to generate an eddy current in a closed loop formed by a conductor portion including patterns on said printed circuit board or patterns and parts on said printed circuit board;
detecting a distribution state of a magnetic field generated by the eddy current with a non-contact state to said printed circuit board being maintained using a magnetic field sensing structure, the magnetic field sensing structure and magnetic field inducing structure being integral; and
determining whether or not any defect exists in said printed circuit board based upon the results of said detecting. - View Dependent Claims (9, 11)
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3. A method for inspecting a printed circuit board comprising the steps of:
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discharging a ultrasonic wave having a predetermined frequency from a position apart from said printed circuit board by a predetermined distance;
detecting a reflected wave from said printed circuit board; and
determining whether or not any defect exists in said printed circuit board based upon the results of said detection. - View Dependent Claims (10, 12)
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4-6. -6. (canceled)
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7. An apparatus for inspecting a printed circuit board comprising:
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a detection unit which applies a magnetic field onto said printed circuit board using a magnetic field inducing structure without physically contacting the printed circuit board to generate an eddy current in a closed loop formed by a conductor portion including patterns on said printed circuit board or patterns and packaged parts on said printed circuit board to detect a distribution state of a magnetic field generated in said printed circuit board by the eddy current using a magnetic field sensing structure, the magnetic field sensing structure and magnetic field inducing structure being integral, while being set in a non-contact state with respect to said printed circuit board;
position adjusting means for adjusting a relative positional relationship between said detection unit and said printed circuit board; and
control means which controls said position adjusting means so as to allow the detection unit to coincide with a predetermined plurality of positions on said printed circuit board in succession so that a determination is made as to whether or not any defect exists in said printed circuit board by using detection signals of the respective positions from the detection unit.
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8. An apparatus for inspecting a printed circuit board comprising:
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a detection unit which discharges a ultrasonic wave having a predetermined frequency to detect a reflected wave from said printed circuit board while being set in a non-contact state with respect to said printed circuit board;
position adjusting means for adjusting a relative positional relationship between said detection unit and said printed circuit board; and
control means which controls said position adjusting means so as to allow the detection unit to coincide with a predetermined plurality of positions on said printed circuit board in succession so that a determination is made as to whether or not any defect exists in said printed circuit board by using detection signals of the respective positions from the detection unit.
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Specification