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Preliminary evaluation of hermetic JT/LJT/R P connector socket contact design

Description: This report presents a precursory examination of a number of issues pertaining to socket contacts in hermetic connectors. The principal issues addressed are high-contact resistance and contact chatter (circuit discontinuities). Efforts examining the characteristics of the existing socket contact design, the possibility of connector/contact rework, quick-fix solutions, and contact redesigns are summarized.
Date: October 1, 1991
Creator: Baca, J. R. F.
Partner: UNT Libraries Government Documents Department

Development of a semi-automated workcell for repair of printed circuit boards

Description: Printed circuit boards that comprise US Army electronic systems are repaired at Army depots. An existing automated diagnostic system determines the area of failure; either by identifying failed components or failed board traces. Currently, repairs are performed manually by trained technicians. A system is being developed for repair of through-hole printed circuit boards. It is comprised of many automated and operator-assisted functions to perform the multiple operations related to replacement of failed components. When completed, this system will demonstrate economic payback by reducing skilled labor requirements and decreasing rework. The semi-automated system integrates human operators into the process while maintaining high productivity. After several fully automated systems were conceived and modelled, it was found that the configuration that provided the best return on investment was comprised of a mix of autonomous and operator-assisted functions. 1 ref., 1 fig.
Date: August 1, 1990
Creator: Bennett, D.W. & Evans, M.S.
Partner: UNT Libraries Government Documents Department

A simplified, improved method for making amplifier equivalent noise charge measurements using a new generation digitizing oscilloscope

Description: Historically a variety of methods have been used to measure the equivalent noise charge (ENC) of amplifier/shaper systems for high energy physics. Some of these methods require several pieces of special test equipment and a fair amount of effort. The advent of digitizing oscilloscopes with statistics capabilities makes it possible to perform certain types of noise measurements accurately with very little effort. This paper describes the noise measurement method of a time invariant amplifier/shaper and of a time variant correlated sampling system, using a Tektronix DSA602 Digitizing Signal Analyzer. 4 figs.
Date: October 1, 1990
Creator: Zimmerman, T.
Partner: UNT Libraries Government Documents Department

A method for encapsulating high voltage power transformers

Description: Voltage breakdowns become a major concern in reducing the size of high-voltage power converter transformers. Even the smallest of voids can provide a path for corona discharge which can cause a dielectric breakdown leading to a transformer failure. A method of encapsulating small high voltage transformers has been developed. The method virtually eliminates voids in the impregnation material, provides an exceptional dielectric between windings and provides a mechanically rugged package. The encapsulation material is a CTBN modified mica filled epoxy. The method requires heat/vacuum to impregnate the coil and heat/pressure to cure the encapsulant. The transformer package utilizes a Diallyl Phthalate (DAP) contact assembly in which a coated core/coil assembly is mounted and soldered. This assembly is then loaded into an RTV mold and the encapsulation process begins.
Date: January 1, 1990
Creator: Sanchez, R.O.
Partner: UNT Libraries Government Documents Department

Capattery double layer capacitor life performance

Description: Double layer capacitors (DLCs) have received increased use in computer memory backup applications for consumer products during the past ten years. Their extraordinarily high capacitance density along with their maintenance-free operation makes them particularly suited for these products. These same features also make DLCs very attractive in military type applications. Unfortunately, lifetime performance data has not been reported in the literature for any DLC component. Our objective in this study was to investigate the effects that voltage and temperature have on the properties and performance of single and series-connected DLCs as a function of time. Evans model RE110474, 0.47-farad, 11.0-volt Capatteries were evaluated. These components have a tantalum package, use welded construction, and contain a glass-to-metal seal, all incorporated to circumvent the typical DLC failure modes of electrolyte loss and container corrosion. A five-level, two-factor Central Composite Design'' was used in the study. Single and series-connected Capatteries rated at 85{degree}C, 11.0-volts operation were subjected to test temperatures between 25 and 95{degree}C, and voltages between 0 and 12.9 volts (9 test conditions). Measured responses included capacitance, equivalent series resistance, and discharge time. Data were analyzed using a regression analysis to obtain response functions relating DLC properties to their voltage, temperature, and test time history. These results are described and should aid system and component engineers in using DLCs in critical applications.
Date: January 1, 1991
Creator: Evans, D.A. (Evans Co., East Providence, RI (USA)); Clark, N.H.; Baca, W.E. (Sandia National Labs., Albuquerque, NM (USA)); Miller, J.R. (Miller (John R.), Shaker Heights, OH (USA)) & Barker, T.B. (Rochester Inst. of Tech., NY (USA). Coll. of Engineering)
Partner: UNT Libraries Government Documents Department

Moisture absorption and bakeout characteristics of rigid-flexible multilayer printed wiring boards

Description: Moisture absorption and bakeout characteristics of Allied-Signal Inc., Kansas City Division (KCD) rigid-flexible printed wiring boards were determined. It was found that test specimens had absorbed 0.95 weight percent moisture when equilibrated to a 50 percent RH, 25{degree}C environment. Heating those equilibrated specimens in a 120{degree}C static air oven removed 92 percent of this absorbed moisture in 24 h. Heating the samples in a 80{degree}C static air oven removed only 64 percent of the absorbed moisture at the end of 24 h. A 120{degree}C vacuum bake removed moisture at essentially the same rate with parylene slowed the absorption rate by approximately 50 percent but did not appreciably affect the equilibrium moisture content or the drying rate.
Date: January 1, 1991
Creator: Lula, J.W.
Partner: UNT Libraries Government Documents Department

Analysis and correction of noise on electronic circuits in an accelerator environment

Description: Accelerator noise sources can cause both analog and digital electronic circuits to malfunction. This paper identifies and analyzes noise sources, and describes the methodology for measurement. Both general remedies and specific solutions to minimize the noise effects on accelerator electronic circuits are described. A policy for electronic design, board layout, assembly, and fabrication is established. Conclusions are drawn based on theoretical principles with practical examples shown in case studies.
Date: January 1, 1992
Creator: Fathizadeh, M.; Despe, O.D. & McGhee, D.G.
Partner: UNT Libraries Government Documents Department

Pulse code modulation data compression for automated test equipment

Description: Development of automated test equipment for an advanced telemetry system requires continuous monitoring of PCM data while exercising telemetry inputs. This requirements leads to a large amount of data that needs to be stored and later analyzed. For example, a data stream of 4 Mbits/s and a test time of thirty minutes would yield 900 Mbytes of raw data. With this raw data, information needs to be stored to correlate the raw data to the test stimulus. This leads to a total of 1.8 Gb of data to be stored and analyzed. There is no method to analyze this amount of data in a reasonable time. A data compression method is needed to reduce the amount of data collected to a reasonable amount. The solution to the problem was data reduction. Data reduction was accomplished by real time limit checking, time stamping, and smart software. Limit checking was accomplished by an eight state finite state machine and four compression algorithms. Time stamping was needed to correlate stimulus to the appropriate output for data reconstruction. The software was written in the C programming language with a DOS extender used to allow it to run in extended mode. A 94--98% compression in the amount of data gathered was accomplished using this method. 1 fig.
Date: May 1, 1991
Creator: Navickas, T.A. & Jones, S.G.
Partner: UNT Libraries Government Documents Department

Ion-optical studies for improved ion transmission in multistage isotope-ratio mass spectrometers

Description: Theoretical and experimental ion-optical studies of multistage isotope-ratio mass spectrometers were conducted to determine what improvement in ion transmission efficiency might be attainable through design changes. The computer program GIOS (General Ion Optical Systems) was used to perform theoretical calculations of focusing properties and ion transmission efficiency. Actual transmission through multiple-sector instruments was determined from measurements of the ion beam vertical profile at the focus of each stage. For existing mass spectrometers with tandem magnets of normal geometry, our studies determined a feasible design change that significantly increases ion transmission through the analyzer. The use of a cylindrical einzel lens or an electrostatic quadrupole lens near the focal point between the magnets provides vertical focusing of the ion beam to achieve the improved transmission. We also established a new mass spectrometer design that give 100% transmission through tandem magnetic analyzers and through a third-stage electrostatic analyzer without the use of an intermediate focusing lens. Non-normal magnetic field boundaries provide ion beam focusing in the vertical plant to achieve this complete transmission. 19 refs., 27 figs., 3 tabs.
Date: October 1, 1991
Creator: Stoffels, J.J. (Pacific Northwest Lab., Richland, WA (United States)) & Laue, H.J. (Purdue Univ., Lafayette, IN (United States))
Partner: UNT Libraries Government Documents Department

Virtual cathode microwave devices -- Basics

Description: Unlike a conventional microwave tube, a virtual-cathode device operates above the space-charge limit where the depth of the space-charge potential can cause electron reflection. The region associated with this electron reflection is referred to as a virtual cathode. Microwaves can be generated through oscillations in the position of the virtual cathode and through the bunching of electrons trapped in a potential well between the real and virtual cathodes. These two mechanisms are competitive. There are three basic classes of virtual cathode devices: (1) reflex triode; (2) reditron and side-shoot vircator; and (3) reflex diode or vircator. The reflex diode is the highest power virtual-cathode device. For the reflex diode the energy exchange between the beam and electromagnetic wave occurs in both the axial and radial directions. In some designs the oscillating-virtual-cathode frequency exceeds the reflexing-electron frequency exceeds the oscillating-virtual-cathode frequency. For the flex diode a periodic disruption in magnetic insulation can modulate the high- frequency microwave power. Overall, particle-in-cell simulation predictions and axial reflex diode experiments are in good agreement. Although frequency stability and phase locking of the reflex diode have been demonstrated, little progress has been made in efficiency enhancement. 58 refs., 11 figs.
Date: January 1, 1991
Creator: Thode, L.E. & Snell, C.M.
Partner: UNT Libraries Government Documents Department

The use of light emission in failure analysis of CMOS ICs

Description: The use of photon emission for analyzing failure mechanisms and defects in CMOS ICs is presented. Techniques are given for accurate identification and spatial localization of failure mechanisms and physical defects, including defects such as short and open circuits which do not themselves emit photons.
Date: January 1, 1990
Creator: Hawkins, C.F. (New Mexico Univ., Albuquerque, NM (USA). Dept. of Electrical and Computer Engineering); Soden, J.M.; Cole, E.I. Jr. & Snyder, E.S. (Sandia National Labs., Albuquerque, NM (USA))
Partner: UNT Libraries Government Documents Department

Assembly Test Chip Version 01 description and users manual

Description: This report describes the features and use of the Sandia National Laboratories Assembly Test Chip Ver. 01 (ATC01). This chip contains a variety of Al conductor features which are intended for use in corrosion testing. These include triple tracks with a variety of line and gap widths, ladder structures, straight line structures, and van der Pauw sheet resistance structures. The chip is square, approximately 0.250 in. on a side, with a minimum Al feature size of 1.25 {mu}m. The various test structures on the die are described in detail and bonding layout data are given. Finally, we give an example of measurements made on ATC01 when packaged in a 40 lead CERDIP. 15 refs., 7 figs., 7 tabs.
Date: September 1, 1990
Creator: Sweet, J.N.; Peterson, D.W.; Tuck, M.R. & Renninger, D.J.
Partner: UNT Libraries Government Documents Department

Detection and frequency tracking of chirping signals

Description: This paper discusses several methods to detect the presence of and track the frequency of a chirping signal in broadband noise. The dynamic behavior of each of the methods is described and tracking error bounds are investigated in terms of the chirp rate. Frequency tracking and behavior in the presence of varying levels of noise are illustrated in examples. 11 refs., 29 figs.
Date: August 1, 1990
Creator: Elliott, G.R. & Stearns, S.D.
Partner: UNT Libraries Government Documents Department

Precision pulse-timing instrumentation for ultrasonic nondestructive testing

Description: A new, pulse-timing discriminator and B-scan time-to-pulse-height converter have been developed for the inspection of production parts. The discriminator is easy to operate and features automatic echo gating and automatic pulse polarity discrimination. This instrument combines the noise-blanking advantages of threshold discrimination with the echo-timing precision of zero-crossing discrimination to improve measurement accuracy by a factor of two over the best precious techniques. When used with the discriminator, the B-scan unit allows detection of flaws at depths less than one-fourth those obtainable with commercially available instruments. 3 refs., 20 figs., 2 tabs.
Date: August 31, 1990
Creator: Duncan, M.G.
Partner: UNT Libraries Government Documents Department

Thermal tests of MC3811 rigid/flex printed wiring boards

Description: Rigid/flex multilayer printed wiring boards are more sensitive to thermal environmental changes than conventional printed wiring boards. This is manifested because of a composition of dissimilar materials used within the construction of this type of product. During fabrication and assembly, stresses can develop within the plated-through holes from differences in thermal properties of the rigid and flexible materials, primarily thermal coefficient of expansion. Thermal shock and thermal stress tests and rework simulation as defined in MIL-P-50884 have been performed in this study as indicators of processing quality to detect faults and to verify improvements in board reliability. 3 refs., 17 figs., 3 tabs.
Date: October 1, 1990
Creator: Gentry, F.L.
Partner: UNT Libraries Government Documents Department

Evaluation of Tektronix (2 gigasample/second) Digital Signal Analyzer DSA 602

Description: The results of evaluating the Tektronix (2 gigasample/second) Digital Analyzer DSA 602 is discussed. Evaluations were done using both the 11A52 and 11A72 amplifier modules. Effective bits tests were run from 2 MHz to 1 GHz. Timing tests were done to verify repeatability of triggering. Baseline data were taken to determine noise levels. Pulse testing was done to determine overdrive recoverability. The stability of the internal calibration was verified. TDR tests were done to determine what reflections would be generated if the inputs were overdriven. 32 figs., 8 tabs.
Date: January 1, 1990
Creator: Graves, T.
Partner: UNT Libraries Government Documents Department

Rise time and recovery of GaAs photoconductive semiconductor switches

Description: Fast rise time applications have encouraged us to look at the rise time dependences of lock-on switching. Our tests have shown rise time and delay effects which decrease dramatically with increasing electric field across the switch and/or optical energy used in activating lock-on. Interest in high repetition rate photoconductive semiconductor switches (PCSS), which require very little trigger energy (our 1.5-cm long switches have been triggered with as little as 20 {mu}J), has also led us to investigate recovery from lock-on. Several circuits have been used to induce fast recovery, the fastest being 30 ns. The most reliable circuit produced a 4-pulse burst of +/{minus} 10-kV pulses at 7 MHz with 100-{mu}J trigger energy per pulse. 11 refs., 10 figs.
Date: January 1, 1990
Creator: Zutavern, F.J.; Loubriel, G.M.; O'Malley, M.W.; McLaughlin, D.L. & Helgeson, W.D.
Partner: UNT Libraries Government Documents Department

Photovoltaic concentrator module reliability: Failure modes and qualification

Description: The purpose of this paper is to discuss the current issues of interest in PV concentrator module reliability. Before describing in detail the reliability concerns about PV concentrator modules, it should be emphasized that, with proper design and attention to quality control, there is nothing to prevent concentrator modules from being as reliable as crystalline-silicon flat-plate modules have proven to be. Concentrator modules tested outdoors, as well as in the first-generation systems, have generally been reliable, and no degradation in cell output has been observed. Also, although they are not included in this paper, there are a few items currently of concern with the reliability of other PV module technologies that are not issues with PV concentrator technology, such as the stability of amorphous-silicon efficiencies and concerns about EVA encapsulation.
Date: January 1, 1990
Creator: Richards, E.H.
Partner: UNT Libraries Government Documents Department

Custom electronic subsystems for the Laboratory Telerobotic Manipulator

Description: The National Aeronautics and Space Administration (NASA) Space Station Program presents new opportunities for the application of telerobotic and robotic systems. The Laboratory Telerobotic Manipulator (LTM) is a highly advanced 7 degrees-of-freedom (DOF) telerobotic/robotic manipulator. It was developed and built for the Automation Technology Branch at NASA's Langley Research Center (LaRC) for work in research and to demonstrate ground-based telerobotic manipulator system hardware and software systems for future NASA applications in the hazardous environment of space. The LTM manipulator uses an embedded wiring design with all electronics, motor power, and control and communication cables passing through the pitch-yaw differential joints. This design requires the number of cables passing through the pitch/yaw joint to be kept to a minimum. To eliminate the cables needed to carry each pitch-yaw joint's sensor data to the VME control computers, a custom-embedded electronics package for each manipulator joint was developed. The electronics package collects and sends the joint's sensor data to the VME control computers over a fiber optic cable. The electronics package consist of five individual subsystems: the VME Link Processor, the Joint Processor and the Joint Processor power supply in the joint module, the fiber optics communications system, and the electronics and motor power cabling. 3 refs., 3 figs.
Date: January 1, 1990
Creator: Glassell, R.L.; Butler, P.L.; Rowe, J.C. (Oak Ridge National Lab., TN (USA)) & Zimmermann, S.D. (TeleRobotics International, Inc., Knoxville, TN (USA))
Partner: UNT Libraries Government Documents Department

Strained-layer electronics and optoelectronics

Description: Strained-layer epitaxy involves more than the dislocation-free growth of dissimilar materials: effective strained-layer epitaxy exploits lattice-mismatch-induced strain to fine-tune material properties. This paper describes strained-layer epitaxy and describes its application to electronic and optoelectronic device to improve performance.
Date: January 1, 1990
Creator: Myers, D.R.
Partner: UNT Libraries Government Documents Department

Evaluation of surface analysis methods for characterization of trace metal surface contaminants found in silicon IC manufacturing

Description: A major topic at recent silicon-based integrated circuit (IC) manufacturing symposia is the pursuit of decreased contamination levels. The aim is to remove contamination from both processes and materials. In conjunction with this effort, characterization methods are being pushed to lower and lower detection limits. In this paper, we evaluate surface analysis methods used to determine the concentration of inorganic contamination on unpatterned Si wafers. We compare sampling depths, detection limits, and applicability of each method for use in support of Si IC manufacturing. This comparison is further limited to Fe and Cu which are transition metal contaminants associated with manufacturing yield loss. The surface analysis methods included in this evaluation are: Total Reflection X-Ray Fluorescence (TXRF or TRXRF); Secondary Ion Mass Spectrometry (SIMS); two post-ionization'' methods Surface Analysis by Laser Ionization (SALI) and Sputter Initiated Resonant Ionization Spectroscopy (SIRIS); Heavy Ion Backscattering Spectroscopy (HIBS); and Vapor Phase Phase Decomposition (VPD) based methods Atomic Absorption (VPD-AA) along with VPD-TXRF. Sets of 6 in. Si wafers with concentration levels between 10{sup 9} atoms/cm{sup 2} and 10{sup 12} atoms/cm{sup 2} Fe and Cu were characterized by TXRF, SIMS, SIRIS, and HIBS. This data allows estimation of detection limits (DLs) and relative method accuracy. In Section 1 we describe each surface analysis method and the circumstance under which it would be used to support Si IC manufacturing. The equipment used for this comparison and the 150 mm Si wafer set are described in Section 2. Results from each method are contrasted in Section 3. Finally, a conclusion is presented in Section 4.
Date: January 1, 1991
Creator: Diebold, A.C.; Maillot, P.; Gordon, M.; Baylis, J.; Chacon, J.; Witowski, R. (SEMATECH, Austin, TX (United States)) et al.
Partner: UNT Libraries Government Documents Department

Circular format zig-zag scanning of vidicon tubes

Description: In an effort to increase camera readout speed, we have developed a nonconventional vidicon tube scanning technique. Because all vidicon targets are round, acquiring a full view requires overscanning with a conventional square format scan, resulting in 22% of the video field time wasted. Furthermore, conventional scanning employs horizontal flyback, which for high frame rates can be more than 10% of the total field time. Our nonconventional scanning technique eliminates flyback time by utilizing a triangular waveform rather than a sawtooth for horizontal deflection. This triangle wave is amplitude modulated in order to scan only the (circular) area of interest. The vertical deflection is a staircase ramp, with a step occurring at the end of each horizontal line. This maintains even spacing and a parallel relationship between horizontal lines, as opposed to skewed lines with conventional scans. To display the video ouput, the X-Y monitor must also be driven with these waveforms in order to maintain the correct temporal and spatial position of the video data. Sweep rates of 400 lines in a 1 ms field have been demonstrated. Test results using this technique show a frame time reduction of {approximately}30%, with no loss of resolution or dynamic range, and no increased video bandwidth requirements. 7 figs.
Date: January 1, 1991
Creator: Peterson, C.G. & Simmons, C.M.
Partner: UNT Libraries Government Documents Department

Performance of a new monolithic eight channel charge sensitive preamplifier-shaper

Description: A monolithic eight channel CMOS time-invariant preamplifier/shaper has been designed and built by Chuck Britton of ORNL in collaboration with Ray Yarema and Tom Zimmerman of Fermilab. Each of the eight channels incorporates a charge sensitive preamplifier and two shaping stages. The resultant weighting function is similar to CR-RC{sup 3}. The peaking time is approximately 200 ns, and the charge gain approximately in the range of 50--70 mv/fc. The layout was done on a Tinychip pad frame and the device was fabricated in a 2{mu} P-well process by Orbit. Figure 1 shows the chip layout. The channels are on an 84{mu} pitch to fit on a Tinychip without folding the layout. The design can be easily expanded to a larger number of channels. This paper describes results of tests performed on this device at Fermilab. The tests were done with a bare die which was directly wirebonded to a printed circuit board. This minimizes parasitic effects which can become significant when using large packages. Results may be somewhat different when using the standard 40 pin package. 6 figs.
Date: August 1, 1991
Creator: Zimmerman, T.
Partner: UNT Libraries Government Documents Department

A high performance multi-channel preamplifier ASIC

Description: A new preamplifier ASIC has been designed and built to improve performance of the VTPC (Vertex Time Projection Chamber) at Fermilab's Colliding Detector Facility. Design of the semicustom IC was completed using a Tektronix Quick-Chip 2S bipolar linear array. The ASIC has 6 channels on a chip and provides lower noise, higher gain, lower power, and lower mass packaging than the device which it replaces. Actual performance of the preamplifier was found to match very closely the simulated performance. To reduce the mass of the complete circuit board, bare IC dice were mounted directly on a G-10 substrate using COB (chip on board) techniques. The preamplifier and packaging should be applicable to numerous other systems. 1 ref.
Date: November 1, 1991
Creator: Yarema, R.J.; Zimmerman, T.; Williams, W.; Binkley, M.; Huffman, T. & Wagner, R.
Partner: UNT Libraries Government Documents Department