Electric Field Uniformity Research Articles

Rapid Cure Of Liquid Encapsulants And Structural Adhesives For Electronics Packaging Using Variable Frequency Microwave (Vfm) Energy

AbstractThis paper reports on the use of an emerging process technique for curing of polymer encapsulants as used in the electronic packaging industry. Previous work performed in the area of materials processing has demonstrated the usefulness of sweeping operating frequencies in order to achieve high levels of electric field uniformity and process control. The use of controlled variable frequency microwave energy has been evaluated as a process technique compatible with electronic packaging requirements. The heating of a series of integrated circuits (ICs) and their subsequent characterization was performed. IC integrity was investigated using X‐Ray, Acoustic Microscopy, Decapsulation and Bond Pull. Processing of liquid encapsulants, underfills and glob‐tops, used in Flip Chip and Chip On Board (COB) applications, was performed. Differential Scanning Calorimetry was used to study cure extent. Further studies show that variable frequency microwave processing leads to fast curing of encapsulants. A reduction in cycle times from 15 to 20 times over conventional curing has been observed. Also, results have showed a reduction in the stresses induced by mismatches in coefficient of thermal expansion.

Field uniformity of discharge lasers: electrode profiles and current return path effects

The influence of the current return geometry on the electric field uniformity in the discharge laser chamber is studied, and a suggestion for better electrode profiles, giving lower electric field spatial gradients, is proposed.

Novel partially corrugated waveguide laser diode with low modulation distortion characteristics for subcarrier multiplexing

A novel partially corrugated waveguide laser diode (PC-LD) for subcarrier multiplexing was proposed. High yield characteristics for low distortion specification (IMD3 ≤ –80 dBc) were demonstrated theoretically and experimentally. This is attributed to the electric field uniformity improvement along the cavity and the grating facet phase insensitivity in the PC-LD.

Large-volume pulsed-RF excited waveguide CO/sub 2/ lasers

Scalable pulsed-RF excitation of a sealed-off non-flowing CO/sub 2/ laser in a configuration compatible with high transverse and high longitudinal mode purity and compatible with very compact laser designs is described. The variation of maximum pulse-repetition frequency (PRF) with discharge transverse dimensions and the effects of electric field uniformity are described. Kinetics code calculations and laser design studies indicate that the results are scalable to the 10-J, 50-Hz level. >

Modeling and characterization of embedded electrode performance in transverse electrooptic modulators

A mathematical model with experimental verification is presented to characterize the performance of surface and embedded electrodes in 2-D electrooptic modulators. From the solution of a discretized integral equation for the electrode surface charge, the electrode capacitance and the electric field penetration and uniformity are related to the switching voltage, speed, and uniformity of the electrooptic modulation. Fabricated surface and embedded electrodes in 9/65/35 PLZT are then evaluated with respect to the predictions of the model and the saturated quadratic response of the electrooptic material. These results provide important insight into the design trade-offs of switching speed, halfwave voltage, switching energy, and modulation uniformity of surface and embedded modulator geometries.

Geometric focusing of intense pulsed ion beams from racetrack type magnetically insulated diodes

Focusing properties and mechanisms are experimentally investigated of an intense pulsed light-ion beam or a medium-mass ion beam extracted from racetrack type magnetically insulated diodes. Quantitative determinations are made for three factors that affect the focusing ability of the beam, i.e., local divergence angle, deviation angle from ideal trajectory and space-charge effect. Behaviour of electrons in an anodecathode gap as well as neutralizing process of the ion beam by electrons are studied in connection with beam focusing. It is found that there is a close correlation between ion yield and electron irradiation on the anode. By adopting a perforated cathode instead of a vane cathode to ensure good uniformity of electric field in the accelerating gap, we have succeeded in significantly reducing the divergence angle. Several new diagnostic techniques and methods have been developed, yielding information such as the time-resolved trajectory and profile or incident angle of the beam. Electron temperature of the anode plasma is theoretically anticipated from the ions observed experimentally. From an estimate of beam divergence due to a space-charge effect, it is suggested that ‘breakeven’ can be achieved without using conventional z-discharged plasma channels if a bunch of boron beams is utilized.

Improving the electric field uniformity in large hybrid focal plane detectors

The characteristics of a large volume hybrid counter consisting of an ionization chamber with a multi-element anode are described. Modifications to the cathode structure have been made in order to reduce the edge effects due to non-uniformities in the electric field distribution arising from the increased cathode-anode separation. Typical measurements obtained with this detector are presented and indicate that the values of the ΔE and E resolutions are similar to those for smaller volume counters.

Biological Effects of 60-Hz Electric Fields on Miniature Swine: Exposure Facility

A facility for the exposure of miniature swine to vertical, 60-Hz, 30-kV/m electrical fields has been constructed. Exposed and sham-exposed colonies of swine are housed in separate, environmentally equivalent buildings. The electric field uniformity over the area of a swine stall is ±2.5% at ground-level and ±8% at the maximum height of a swine. The swine are not subject to spark discharges. The current between a drinking swine and its water nozzle is less than 20 ?A. No levels of audible noise, hum, vibration, or ozone attributable to the high-voltage system have been detected. The total electric field harmonic distortion is 0.5%.

Electrical equivalent circuits of D.C. MHD generators

In the paper the equivalent circuits of generators with the segmented electrodes electrically connected in various ways are determined (generators with the electrodes connected in series, with Halland Faraday-connected electrodes). Constant gas dynamic parameters, constant generator cross-section, constant magnetic field and uniformity of current density and electric field are assumed. Electrode effects, end effects and “ion slip” are neglected. From the equivalent circuits the electrical terminal values of the generator as a function of the geometric dimensions of the generator, the Hall parameter and the connexions system of electrodes can easily be determined.

Improvements in Large Volume Coaxial Germanium Spectrometers

Large volume (16-54 cm3) germanium lithium drift diodes coaxially drifted with one open end have shown excellent performance as ?-ray spectrometers. However limitations have been found in the coincidence resolving times possible with short coaxial diodes due to large variations in charge collection times which result from the non-uniformity of the electric field - especially in the closed end portion. Leading edge time distributions as a function of axial position were made on a longer (6.6 cm) coaxial diode with one open end using 511 keV ?-rays. In an attempt to improve the electric field uniformity, the closed end was cut off to produce a double open-ended detector 4.2 cm long, and a single open ended detector 2.1 cm long. Both diodes were excellent spectrometers. In the 4.2 cm detector (C = 55 pF) the full width at tenth maximum W0.1 of the leading edge time distributions varied from 34 nsec to 19 nsec due to a large variation in core size along the axis. In the 2.1 cm detector (C = 34 pF) W0.1 varied from 17 nsec in the coaxial region to 30 nsec at the closed end. A 6.1 cm long coaxial diode was made with two open ends, a circular crosssection, and a circular core cross-section nearly uniform along the length. W0.1 of the leading edge time distribution for this improved diode was 19 nsec for the whole detector, and varied by less than 2 nsec from end to end.

Electric Field Uniformity in Terminated Condensers

Electric Field Uniformity in Terminated Condensers