Marker probe

Abstract

A test fixture for testing printed circuit boards comprises an array of electrically conductive test probes mounted within the fixture, a marker probe mounted for contact with the board, and a marker probe drive motor for rotating the marker probe in response to an input signal from a circuit board tester. During testing, the test probes contact the board to produce a test signal indicating pass/fail status of the board. At the same time the marker probe is drawn into spring-biased contact with the board. For each board that passes the test, the test signal operates the drive motor for a short time interval to rotate the marker probe to apply an identifying mark to the board, indicating that the board has passed the test. In one embodiment, the marker probe includes a plunger on an output shaft of the drive motor, in which the marker probe is secured to the plunger eccentric to the motor shaft axis of rotation. A spring biases the plunger when the plunger moves axially relative to the motor output shaft, thereby producing spring biased contact between the marker probe and the board. Operation of the drive motor rotates the plunger and thereby rotates the eccentrically mounted marker probe which is held in spring-biased contact with the board. This produces a permanent identifying mark on the board, preferably by the marker probe being rotated for a fraction of a second, which removes a small area of the board's plastic coating to expose the underlying copper layer that provides the permanent and easily visible mark on the board.