Printed circuit board tester using magnetic induction
First Claim
1. Apparatus for testing a populated printed circuit board for faults comprising:
- a fixture having a plurality of conductive members adapted to make contact to a printed circuit board positioned in the fixture;
an antenna mounted near the fixture;
a bias source connected to one of the plurality of conductive members; and
a receiver connected to the bias source.
3 Assignments
0 Petitions
Accused Products
Abstract
An apparatus and method are disclosed for testing connections between printed circuit boards and components mounted thereon. A conductive loop is formed by forward biasing a parasitic diode that is inherently present between an integrated circuit (IC) lead and the ground plane of the IC. A magnetic field is created by an antenna mounted above the component to be tested. When the antenna is energized by an RF source, a voltage is induced in the conductive loop if the loop is continuous, i.e., if all of the connections are properly made. The voltage in the loop is measured and compared to a selected threshold to produce a pass/fail indication. This tester may be implemented as an improvement to a standard type of "bed-of-nails" printed circuit board tester. The antenna may be implemented as an array of spiral loop antennas, with adjacent antennas producing magnetic fields that are 90 degrees out of phase with each other.
100 Citations
29 Claims
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1. Apparatus for testing a populated printed circuit board for faults comprising:
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a fixture having a plurality of conductive members adapted to make contact to a printed circuit board positioned in the fixture; an antenna mounted near the fixture; a bias source connected to one of the plurality of conductive members; and a receiver connected to the bias source. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. Apparatus for testing a populated printed circuit board for faults, comprising:
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a fixture having a plurality of conductive members adapted to make electrical contact with conductive traces on a printed circuit board; a radiating antenna positioned near the fixture; a bias source connected to one of the conductive members; means for measuring a signal induced in the printed circuit board by a magnetic field created by the radiating antenna, said means for measuring being electrically coupled to at least one of the conductive traces on the printed circuit board.
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12. Apparatus for testing a printed circuit board for open circuit defects, the printed circuit board having electronic circuits mounted thereon which include inherent parasitic diodes, comprising:
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a bed-of-nails fixture having a plurality of conductive pins; an array antenna comprising a plurality of antenna elements adapted to radiate energy toward the fixture; a signal source connected to the array antenna; means for connecting the signal source to selected ones of the antenna elements; a DC bias source connected to one of the plurality of conductive pins for producing a bias current sufficient to forward bias the parasitic diodes; and a receiver connected to the DC bias source. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A method for testing a populated printed circuit board for open circuit faults comprising the steps of:
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establishing a loop on the printed circuit board including a selected integrated circuit chip that is mounted on the printed circuit board; radiating an alternating magnetic field toward the selected integrated circuit chip; detecting the voltage induced in the loop; and indicating that the selected integrated circuit chip is not properly connected to the printed circuit board when the detected voltage is below a selected threshold voltage. - View Dependent Claims (19, 20, 21, 22, 23)
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24. An apparatus for testing a printed circuit board upon which electronic components are mounted to detect faulty connections between a lead of a selected component and conductive traces on the printed circuit board, comprising:
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means for forming a loop on the printed circuit board, said loop including said lead of said selected component; means for generating an alternating magnetic field that intersects the loop; and means for detecting a signal induced by said alternating magnetic field in the loop. - View Dependent Claims (25, 26, 27, 28, 29)
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Specification