Hewlett-packard Company

Agilent Technologies, Inc.

Philip N King

Stephen Willard

David T Crook

John E McDermid

John E Siefers

Wayne R Chism

Carroll E Morris, Jr

T Risselle Richert

The present invention is directed to a method for an electrically conductive structure on a printed circuit board for connecting an element on the printed circuit board with other elements. The electrically conductive structure may include a contact pad on a first side of the printed circuit board and two or more connection pads on the first side of the printed circuit board. The two or more connection pads are in close physical proximity to the contact pad and electrically connected to the contact pad. The element on the printed circuit board is directly connected to one the two or more connection pads electrically. The structure permits various engineering changes to the electrical connections of elements on the printed circuit board by desoldering electrical connections to the two or more connection pad, by severing traces to the connection pads, or by severing the electrical connection between the connection pads and the contact pad.

Method for making electrical connections to an element on printed circuit board

A novel thin wire connector cable and method for connecting an electrical test instrument to an electrical node of interest sealable within a vacuum chamber of an electrical testing device is presented. The thin wire connector cable includes a thin wire cable with a first end connectable to the test instrument and a second end comprising a connector electrically connectable to the electrical node of interest that lies within the vacuum-sealable chamber. The thin wire cable is routed from the vacuum-sealable chamber to the test instrument in between a flexible vacuum seal and an opening to the vacuum-sealable chamber such that when the vacuum is actuated, the thin wire cable is wedged between the seal and testing device. The thin wire cable is substantially thin enough so as to prevent more than a negligible amount of leakage between the thin wire cable and the flexible vacuum seal, which allows a vacuum to be generated and maintained.

Connector cable and method for probing vacuum-sealable electronic nodes of an electrical testing device

An electrically conductive structure and method for making circuit changes on a printed circuit board involves the use of electrically conductive tape to connect two previously unconnected points on the board. One or more sections of the tape may be used to form a low-profile contiguous path between two previously unconnected points on the board.

Electrically conductive structure and method for implementing circuit changes on printed circuit boards

The present disclosure relates to a method and apparatus for determining the electrical continuity of an element of an electrical component, for example, a pin of a printed circuit assembly. The method comprises the steps of supplying an electrical stimulus to the element of the electrical component, positioning a sensor adjacent the element of the electrical component, the sensor having multiple axes along which the sensor is responsive to magnetic fields, receiving magnetic field signals created by the element of the electrical component with the sensor, producing electrical signals indicative of the magnetic field strength sensed by the sensor in multiple directions that correspond to the multiple axes, and comparing the electrical signals with predetermined limits associated with the element being tested. In a preferred arrangement, the sensor is provided with three axes which are oriented in orthogonal directions such that the magnetic signals from the element can be detected in three dimensional space.

Multiple axis magnetic test for open integrated circuit pins

A method of determining whether an electrolytic capacitor is properly connected or reversed in an electronic assembly. In a first embodiment, a non-contacting probe is placed near but not touching the body of the device under test (DUT). One terminal of the DUT is driven by a stimulus (voltage source or current source) while the other terminal is connected to a reference voltage. A voltage is measured at the probe relative to the reference voltage and the device is properly oriented if the measured voltage exceeds a predetermined threshold. In a second embodiment, current through the probe is measured instead of voltage at the probe. In a third embodiment, a non-contacting probe is placed near but not touching both leads of the DUT. Each DUT lead is alternately driven by a stimulus and alternately connected to a reference voltage. For each of the two lead test configurations, a voltage at each DUT lead is measured and current through the non-contacting probe is measured. Two algebraic electromagnetic coupling coefficients are computed from the four voltage measurements and the two current measurements. The relative size of the electromagnetic coupling coefficients determines the measured polarity of the DUT. An alternative configuration for any of the embodiments is to drive the probe instead of a terminal of the DUT.

Test for determining polarity of electrolytic capacitors within electronic assemblies

An algorithm selects probe locations for both test signal probes and ground probes in a short-wire board test fixture. The board test fixture connects a test system to a circuit board under test. The algorithm minimizes ground bounce. The algorithm envisions first superimposing an imaginary grid of squares over the circuit board. Then, ground probe locations are derived so that no more than five test signal probes for each ground probe reside within each of the imaginary squares and so that each critical test signal probe is associated within a preselected distance of a ground probe. In the preferred embodiment, the imaginary square measure 1.4 inches on a side, and the preselected distance is approximately one inch.

Method for control of ground bounce above an internal ground plane in a

Algorithms are set forth for positioning critical test signal pins in a short-wire board test fixture so as to efficiently minimize ground bounce. The board test fixture interfaces a test system to a circuit board under test. Critical signals are those signals susceptible to ground bounce. The test signal pins connect a ground plane in the board test fixture to pin cards interfaced to the board test system. Each pin card has a first column of test signal pins and a set of first ground pins. Moreover, each pin card has a second column comprising a set of second ground pins. In order to minimize ground bounce, no more than fifteen second ground pins per pin card are inactive. No more than two consecutive second ground pins per pin card are inactive. Any critical test signals are assigned within three pins of an exclusive first ground pin. Finally, any ordinary test signals are assigned more than four pins from any critical test signals.

Method for the control of ground bounce below an internal ground plane

A driver circuit for use in a circuit board tester performs both functional and in-circuit tests on a given device under test (DUT). The tester provides a control signal representative of a command for the driver circuit to provide test signals to the DUT. The driver circuit incorporates two stages: a pre-driver stage and a driver stage. The pre-driver stage consists of an amplifier connected to fast switching transistors with the ability to move in and out of saturation rapidly. The amplifier receives control signals and the switching transistors provide actuation signals to the driver stage. The driver stage comprises two emitter follower transistors that operate exclusively in an unsaturated state. The driver stage provides test signals to the DUT in response to the actuation signals from the two switching transistors of the pre-driver stage. Additionally, the driver circuit may be programmed to change the output voltage amplitudes of the test signals.

Driver circuit for circuit tester

A driver circuit (10) for selecting particular values of backmatch impedance (Z) for a functional or in-circuit test system. The test system (100) generates the backmatch impedance select signals (32A), the control signals (32B), and the drive data (32C). A decode circuit (200) receives the backmatch impedance select signal and the control signals from the test system for activating one or more of a plurality of individual drivers. Each of the plurality of drivers has a three state control input (202A), a data input (212), and an output (214). Each output of the drivers is connected to an impedance (Z). Hence, a plurality of impedances are provided which are commonly tied together and connected to the transmission line (70). The test system connects one or more of the drivers together. When one driver is selected, that particular value of backmatch impedance is connected to the transmission line. When more than one driver is connected, a resultant parallel impedance value is interconnected to the transmission line. Thus, precise value of backmatch impedance can be connected to the transmission line.

Switched drivers providing backmatch impedance for circuit test systems

An apparatus for preventing damage to the output stage of a driver circuit for use in an overdrive/functional tester, while the output stage is providing logic high or logic low signals, is shown to include a first sensor for sensing the current in the output stage, a second sensor for sensing the voltage in the output stage, a multiplier for multiplying the sensed current with the sensed voltage to determine the power dissipated in the output stage, a filter to account for thermal/time characteristics in the determined power dissipated and a comparator for comparing the filtered power with a power reference value and for generating an indication signal reflective of such comparison.

Method and apparatus for providing thermodynamic protection of a driver

A driver circuit for use in a circuit board tester which tester can perform both functional and in-circuit tests on a given device under test (DUT). The tester provides a test signal representative of a command for the driver circuit to provide logic high or logic low signals to a given device under test (DUT). The driver includes an output stage for providing desired logic high and logic low signals in response to the test signal; and switch circuitry, connected between the tester and the output stage, for preventing the test signal from reaching the output stage in response to a second control signal. The driver circuit is also shown to include an amplifier which, during operation of the driver circuit, receives feedback from the output stage. In addition, the driver circuit includes another output stage which provides a feedback signal when the driver circuit is in tri-state (deactivated). The driver circuit provides a low output impedance when logic high and logic low signals are being provided and a high output impedance when the driver circuit is in tri-state.

Driver circuit for in-circuit overdrive/functional tester

A method and apparatus for providing pulse signals from a driver circuit in an in-circuit overdrive/functional tester to a probe, which tester provides a control signal representative of a command for the driver circuit to provide logic signals, includes adjusting the transition time of the logic signals so that the transition time is equal to twice the time it takes the pulse signal to travel from the driver circuit to the end of the probe and back. The method or apparatus for adjusting the rise time of the control signal can include adjusting the slew rate of the control signal. Pulse signals produced by such a method or apparatus have clean edges, have slew rates which are twice as fast as the slew rates of the driver signals and have zero propagation delay when measured at the fifty percent point.

Growing community of inventors

Ft. Collins, CO, United States of America

Philip N King