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Test fixture alignment system for printed circuit boards

  • US 5,408,189 A
  • Filed: 12/14/1992
  • Issued: 04/18/1995
  • Est. Priority Date: 05/25/1990
  • Status: Expired due to Fees
First Claim
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1. In a test fixture for testing printed circuit boards and the like, the test fixture being of the type having a board mounting plate, an array of test probes mounted on a probe plate for contact with a pattern of test points in a printed circuit array on the board, the circuit array being positioned on the board with reference to a fiducial mark on the board, the board also having an alignment device positioned thereon in alignment with the circuit array, the improvement comprising:

  • a tooling pin rigidly affixed to the board mounting plate for engaging the alignment device on the board to hold the board and its circuit array in a fixed position relative to the array of test probes on the probe plate;

    sensing means mounted in a fixed position for sensing the position of the fiducial mark as the board moves relative to the sensing means and the array of test probes to produce an output representative of the alignment or misalignment of the array of test probes relative to the circuit array on the board; and

    drive means for moving the board mounting plate relative to the probe plate and the test probes for thereby moving the circuit board relative to the fixed sensing means to correct any misalignment of the circuit array relative to the array of test probes, the sensing means producing said output to indicate the precise movement of the board mounting plate to an adjusted position relative to the probe plate necessary to align the sensing means with the fiducial mark to thereby indicate precise alignment of the test probes with corresponding test points in the circuit array on the board;

    the drive means comprising an X-axis drive motor and a Y-axis drive motor each having an output shaft coupled to the board mounting plate to produce X and Y-axis travel of the board mounting plate, and further drive means to produce Z-axis rotational motion of the board mounting plate to move the circuit board relative to and generally parallel to the fixed probe plate and the sensing means to thereby correct said misalignment.

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