Abstract: The present invention is a dual stage latch assembly with a cam follower pin mounted on a spring-tensioned arm, especially useful for vacuum test fixtures for printed circuit boards. The arm is spring-loaded on both sides, so that the arm is always biased to the upright and neutral position, regardless of which direction the arm is pivoted. A catch is provided to define the path of the cam pin and to hold the cam in certain positions. The cam pin follows a defined path around the catch, creating a first closed stage, a first release position, a second closed stage and a final release position.

Abstract: A translator fixture for a grid-type test fixture for testing circuit boards. In regions of the circuit board where test point density exceeds the grid spacing of probes in a grid base the test points are reached by a test module that plugs into the translator fixture and includes a grid pattern of feed-through probes for contacting special tilt pins connected to certain test points in the high density region of the board. Additional test probes, located between the rows and columns of feed-through probes, support special tilt pins for translating the remaining test points in the high density region of the board to contacts on flex circuit-type cables sandwiched on the module and extending to the periphery of the fixture for coupling to contacts on the grid base to communicate with test circuits in the test analyzer.

Abstract: A test fixture assembly releasably retains a printed circuit board on a test fixture and facilitates transfer of the board to and removal of the board from the fixture during a sequential test operation in which circuit boards under test are held in a test position, tested by a printed circuit board test apparatus, removed from the test position, and unloaded from the fixture, followed by receiving further boards in sequence for testing. The test fixture includes conductive test pins aligned with circuits on the board to be tested, and at least one board retaining assembly mounted to the fixture. The board retaining assembly includes a board retaining device positioned adjacent a surface of the test fixture and affixed to a free end of an elongated support member rigidly connected to the fixture.

Abstract: A quick stacking translator fixture for a printed circuit board tester has a pattern of test probes on a base upon which the translator fixture is mounted. The translator fixture comprises a plurality of essentially parallel and vertically spaced apart rigid translator plates having selected patterns of aligned holes for positioning translator pins for contacting test points on a printed circuit board supported at one end of the translator fixture. The translator pins translate electrical test signals between the test points on the printed circuit board and the test probes on the base of the tester. The translator fixture includes a plurality of translator plate stacking towers of identical construction supporting the translator plates in their fixed positions in the translator fixture.

Abstract: A one-piece contact probe comprises a plunger member and a compliant spring section contained in and guided for spring biased axial travel in a tubular outer barrel, in which the plunger member, spring section and barrel are jointly formed of a single integral spring metal piece. In the process for making the compliant contact probe a thin bendable sheet metal piece is formed having a generally flat profile defining the plunger section, the spring section and the barrel section in that order along the integral spring metal piece. The plunger section and the integral spring section are bent from the generally flat profile into a generally tubular-shaped compliant plunger member. The barrel section is rounded from its generally flat profile into a curved profile which is then folded back over the compliant tubular plunger member after which bending of the barrel section is completed to form a generally tubular barrel disposed around the internal compliant plunger member.

Abstract: A test fixture provides ESD protection to electronic switching circuitry in a universal grid type fixture having test probes arranged for electrical contact with a printed circuit board under test and in which test signals are sent between the circuit board and a high speed electronic test analyzer through intervening switching circuits. The test fixture includes a movable probe plate, a test probe mounted in the probe plate, the test probe including a movable plunger for making electrical contact with a printed circuit board during a test cycle, the plunger being movable between a first position and a second position, and a ground plane on the movable probe plate connected to electrical ground, the probe plunger having a ground plane contact element that contacts the ground plane in said first position of the plunger and which moves out of the contact with the ground plane when the plunger moves to the second position.

Abstract: Telescoping spring probes include a barrel having a hollow cylindrical body with a passageway extending from a closed barrel end to an open barrel end. The open barrel end is crimped radially inward into the passageway. A plunger axially disposed within the barrel passageway comprises a hollow body having an internal cavity extending from an open plunger end to a closed plunger end. The open plunger end disposed within the barrel passageway faces the closed barrel end. The plunger body has an outside surface portion with a diameter greater than the crimped barrel open end to prevent the plunger from exiting the barrel. A spring is disposed axially within the barrel passageway and the plunger cavity. In a first embodiment, the plunger body includes an inwardly deflected detent contacting one end of the spring to imposes a spring force which biases the plunger body against the barrel passageway.

Abstract: A translator fixture for a grid-type test fixture for testing circuit boards. In regions of the circuit board where test point density exceeds the grid spacing of probes in a grid base the test points are reached by a test module that plugs into the translator fixture and includes a grid pattern of feed-through probes for contacting special tilt pins connected to certain test points in the high density region of the board. Additional test probes, located between the rows and columns of feed-through probes, support special tilt pins for translating the remaining test points in the high density region of the board to contacts on flex circuit-type cables sandwiched on the module and extending to the periphery of the fixture for coupling to contacts on the grid base to communicate with test circuits in the test analyzer.

Abstract: A test fixture for testing circuit boards has a vacuum chamber between a stationary probe plate and a movable top plate. Separate adjustable linear bearings located in quadrants of the fixture provide parallel alignment between the top plate and the probe plate. A continuous vacuum seal between the probe plate and top plate bypasses the bearings so the bearings are outside the vacuum area. Spring loaded test probes in the probe plate extend through holes in the top plate for access to a circuit board under test. The probes contact the board when the top plate moves down toward the probes under a vacuum. The top plate is secured to the probe plate by separate quick-release latch pins extending through the linear bearings. The moving top plate carries fixed tooling pins for mounting the board to the top plate. Movable bearing blocks support the bearings. The top plate is movable for aligning the board with the test probes.

Abstract: An electrical spring probe includes a barrel having an annular opening therethrough. A plunger is partially disposed within the annular opening at one end and is capable of slidable axial displacement within the annular opening. The plunger includes a tip positioned outside of the barrel for contacting an electrical device. A terminal member is disposed within the annular opening through the barrel at an end opposite to the plunger and is fixedly attached therein. The terminal member includes a flanged end that is positioned outside of the barrel and includes at least one flange that extends radially outward from the flanged end. The flange has a shoulder that is substantially perpendicular to an axis running along the terminal member. A slot is positioned in the flanged end and extends axially along the terminal member from tip of the flanged end a distance toward the barrel.

Abstract: A translator pin retention system for a translator fixture for a printed circuit board tester having a pattern of test probes facing away from a base plate upon which the translator fixture is mounted. The fixture comprises a plurality of essentially parallel and spaced apart translator plates having patterns of preformed holes for containing and supporting straight, solid translator pins extending through the plates of the translator fixture for use in translating test signals between test points on a printed circuit board supported by the fixture and the test probes on the base of the tester. A thin, flexible pin retention sheet of an elastomeric material rests on one of the translator plates so that the translator pins that extend through the translator plate on which the sheet rests also extend through the pin retention sheet.

Abstract: A circuit board tester for converting a bare board circuit tester from a wired to a grid type tester comprises an upper probe plate having a plurality of upper test probes arranged to connect with a front side of a PCB and a grid module having a lower probe plate containing a recessed portion for accommodating a plurality of lower test probes mounted on a translator fixture. The lower test probes connect at one end with a plurality of grid pins arranged in a standard grid pattern in the recessed portion of the lower probe plate. The lower test probes connect at the other end with a back side of the circuit board under test. A stripper plate is disposed on the lower pin grid, and the translator fixture is mounted on the stripper plate for translating the lower test probes from the standard grid pattern to a random off-grid pattern corresponding with test points in circuits on the back side of the board.

Abstract: Integrated circuit (IC) packages mounted on a loaded printed circuit board (PCB) are tested by a translator module by first placing a corresponding module over each package. Each module has rows of spring contacts for releasably contacting corresponding electrical leads adjacent opposite sides of the IC package. An upper surface of the module has an array of electrically conductive test pads internally connected to corresponding contacts on the module. The test pads match an array of spring probes in the test unit. The module can be a molded plastic housing with metal leaf spring contacts, or it can comprise a composite flex-circuit material with individual contacts comprising flexible spring-like metalized plastic fingers. Contacts on the test module can releasably engage the leads on the IC package directly, or they can contact separate conductive leads on the PCB adjacent the leads on the IC package.

Abstract: A test fixture for testing circuit boards has a vacuum chamber between a stationary probe plate and a movable top plate. Separate adjustable linear bearings located in quadrants of the fixture provide parallel alignment between the top plate and the probe plate. A continuous vacuum seal between the probe plate and top plate bypasses the bearings so the bearings are outside the vacuum area. Spring loaded test probes in the probe plate extend through holes in the top plate for access to a circuit board under test. The probes contact the board when the top plate moves down toward the probes under a vacuum. The top plate is secured to the probe plate by separate quick-release latch pins extending through the linear bearings. The moving top plate carries fixed tooling pins for mounting the board to the top plate. Movable bearing blocks support the bearings. The top plate is movable for aligning the board with the test probes.

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.

Abstract: A test fixture for testing circuit boards includes an array of test probes mounted to a probe plate and held in contact with test points in circuits printed on the board. The circuit array is indexed with respect to a fiducial mark on the board. The fiducial mark is sensed, and an optical reading shows the alignment or misalignment of the test points on the board relative to the probes. The top plate position is adjusted to move the board relative to the probes to correct misalignment. The optical reading indicates movement of the board to a corrected position necessary to align the test points to the probes. Board alignment can be optically sensed by a bore scope and an image enlarger and video probe that produce images of the fiducial mark and a known zero reference point on a video monitor. The zero reference is adjustable electronically during calibration.

Abstract: A spring biased test probe for testing electrical printed circuit boards includes an elongated tubular barrel having an open end, and a compression spring within a spring seating end of the barrel, opposite from its open end. A plunger inserted in the barrel reciprocates during testing, sliding within the barrel and biased by the spring pressure. The plunger includes a forward end portion outside the barrel, a slidable tail portion that contacts the spring and slides within a barrel, and an intermediate twisted portion between the forward end and the tail portion of the plunger. The forward end of the plunger has a probe tip configured to make frictional pressure contact with the board to be tested. The intermediate portion is twisted about its axis to form a spiral with helical grooves contacted by circumferentially spaced apart crimps in the side of the barrel, adjacent the open end of the barrel.

Abstract: A test module tests integrated circuit (IC) packages mounted on a loaded printed circuit board (PCB) by first placing the module over the package. Each module has rows of test probes for electrically contacting corresponding electrical leads on the IC package. Solid test probes are mounted in a housing in the test module so that electrical connection is achieved between the probes and a flexible printed circuit board that communicates electrical test signals from an external circuit test analyzer to the probes. A thin, flexible elastic diaphragm is mounted across the ends of the test probes so that the diaphragm is elastically movable away from the housing in response to axial pressure from the test probes being pressed against the leads of the IC package. The diaphragm stretches and thereby provides a spring force against the test probes. The test module is used in test fixtures by mounting the test modules in a probe plate spaced from IC packages to be tested.

Abstract: A test fixture for testing printed circuit boards includes an array of test probes held in contact with a pattern of test points in a circuit array printed on the circuit board. The circuit array is positioned on the board with respect to a fiducial mark on the board, and a tooling pin hole on the board is aligned with the circuit array. The fixture includes a tooling pin inserted in the tooling pin hole to hold the circuit array in a fixed position relative to the test probes during testing. The fiducial mark is sensed, and an optical reading shows the alignment or misalignment of the test points on the board relative to the probes. The tooling pin is adjusted on the fixture to move the board relative to the probes to correct misalignment. The optical reading indicates movement of the tooling pin and board to a corrected position necessary to align the circuits on the board to the probe field.