Vacuum-actuated test fixture for testing printed circuit boards

Abstract

A test fixture for testing a circuit board, comprising a top plate defining a board-bearing surface for receiving the circuit board to be tested thereon. The test fixture comprises a lid having a lid frame defining a peripheral rim, and a lid diaphragm movably mounted to the frame opposite the peripheral rim; the lid diaphragm defines an inner surface to which is mounted a circuit board securing member. The lid is movable between a first position where the frame rim engages the top plate to define a test chamber about the board-bearing surface and between the top plate, the frame and the diaphragm, and a second position where the lid is moved away from the top plate to allow access to the test chamber. The lid diaphragm is movable relative to the frame at least when the lid is in the first position between a rest position where the securing member is moved away from the board-bearing surface and an operative position where the securing member is moved towards the board-bearing surface for engaging and securely holding the circuit board thereon. The test fixture further comprises a diaphragm biasing member continuously biasing the diaphragm towards the rest position, and an actuator, for selectively forcibly moving the diaphragm towards the operative position against the bias of the diaphragm biasing member. Moreover, the test fixture comprises at least one test probe projecting from either one of the lid and the top plate towards the board-bearing surface when the lid is in the first position and the diaphragm is in the operative position for allowing the at least one test probe to engage the circuit board. The test fixture also comprises a circuit interface for connecting the probes to a computer.