Printed circuit board tester using magnetic induction

Apparatus for testing a populated printed circuit board for faults, comprising:

• 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.

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:

• 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.

A method for testing a populated printed circuit board for open circuit faults comprising the steps of:

• 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.

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:

• 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.