Electrical Characterization of Thin-Film Polymer Tantalum Capacitors

Polymer Hermetic Sealed (PHS) Tantalum capacitors are advanced Polymer Tantalum capacitors with moisture sealed in the capacitor via hermetically sealing the device inside a package. Their attractive features include high volumetric efficiency, leakage current stability, and low weight as compared to wet and solid-state polymer Ta capacitors. Moreover, recent studies have observed certain interesting properties in PHS Ta capacitors like Breakdown Voltage (BDV) being greater than Formation Voltage, anomalous transient currents, and Capacitance Stability issues. In this thesis, a technique to accurately perform the electrical characterization of thin-film MIS polymer Ta capacitors is established in order to understand the properties observed in PHS Ta capacitors. BDV greater than Formation Voltage is observed in these thin-film MIS capacitors which bolsters our hypothesis that this amazing phenomenon is primarily due to the material layers and their interactions, as opposed to being primarily due to the complex structure of KEMET’s PHS Ta capacitors. Moreover, Capacitance Stability is observed in thin-film MIS devices. The C(T) results are observed to be closely following the dielectric constant k(T) for almost the entire range of temperature, i.e., -55˚C to 150˚C. This result suggests that the thin-film MIS capacitors have capacitance dependence on temperature primarily due to the natural dependence of its dielectric material. In addition, Poole-Frenkel leakage mechanism is observed in some of the thin-film MIS capacitors. Thin-film MIS capacitors are established as viable, inexpensive, and easily fabricated models of KEMET PHS Ta capacitors to improve the Capacitance Stability and Breakdown Voltages of existing PHS Ta capacitors

Capacitance Stability of Polymer Tantalum Capacitors Under Different Environmental Conditions

Polymer Hermetic Sealed (PHS) Tantalum capacitors with pre-polymerized PEDOT cathodes and different dielectric thicknesses were used to study the stability of Polymer Tantalum capacitors under different environmental conditions. In particular, capacitance dependence on temperature, frequency, and dc bias voltage were studied in humid and dry capacitors with varying dielectric thicknesses. Capacitance and ESR measurements were performed to characterize the capacitors.Humid capacitors were observed to have higher capacitance than dry capacitors for all dielectric thicknesses. The capacitance for all dielectric thicknesses was observed to increase with temperature in both humid and dry capacitors. Humid capacitors showed a stronger temperature dependence at lower temperatures while dry capacitors showed a stronger temperature dependence at higher temperatures. These temperature effects were more pronounced in thinner dielectric capacitors, and the results were explained by the integrity of the dielectric-polymer interface. The capacitance for all dielectric thicknesses was also observed to decrease with an increase in frequency, both in humid and dry capacitors. The frequency effect was more pronounced in humid capacitors with thinner dielectrics. These results were explained by the RC ladder effect, secondary transitions of the polar segments of the polymer cathode, and lower reactance and lower self-resonance frequency of the thinner dielectric capacitors

Efficiency Improvement of LDO Output Based Linear Regulator With Supercapacitor Energy Recovery – A versatile new technique with an example of a 5V to 1.5V version

Supercapacitors are used in various industrial applications and the supercapacitors technology is gradually progressing into a mature state. Common applications of supercapacitors are in electric vehicles, hybrid electric vehicles, uninterruptible power supply (UPS) and in portable devices such as cellular phones and laptops. The capacitance values range from fractional Farads to few thousand Farads and their continuos DC voltage ratings are from 2V to 6V. At University of Waikato, a team works on using supercapacitors for improving the efficiency of linear voltage regulators. In particular, this patented technique aims at combining off the shelfs LDO ICs and a supercapacitor array for improving end to end efficiency of linear regulator. My work is aimed at developing the theoretical background and designing prototype circuitry for a voltage regulator for the case of unregulated input supply is more than 3 times of the minimum input voltage requirement of the LDO which is applicable for a 5V to 1.5V regulator. Experimental results are indicated with future suggestions for improvement

Retention and application of Skylab experiences to future programs

The problems encountered and special techniques and procedures developed on the Skylab program are described along with the experiences and practical benefits obtained for dissemination and use on future programs. Three major topics are discussed: electrical problems, mechanical problems, and special techniques. Special techniques and procedures are identified that were either developed or refined during the Skylab program. These techniques and procedures came from all manufacturing and test phases of the Skylab program and include both flight and GSE items from component level to sophisticated spaceflight systems

Bubble memory module

Design, fabrication and test of partially populated prototype recorder using 100 kilobit serial chips is described. Electrical interface, operating modes, and mechanical design of several module configurations are discussed. Fabrication and test of the module demonstrated the practicality of multiplexing resulting in lower power, weight, and volume. This effort resulted in the completion of a module consisting of a fully engineered printed circuit storage board populated with 5 of 8 possible cells and a wire wrapped electronics board. Interface of the module is 16 bits parallel at a maximum of 1.33 megabits per second data rate on either of two interface buses