A power system is normally composed of a large number of generators and transmission lines that are connected through switching stations and substations. The quality and availability of power supply to the customer is highly dependent on the performance of the station equipment. Research shows that station related outages can have considerable impact on the composite system reliability. The individual station components, the station configurations and the terminal connection topologies are important factors in bulk system reliability evaluation. The major components in a station are circuit breakers, bus bars and transformers and these elements are periodically removed from service in order to conduct preventive maintenance. The removal of equipment for maintenance creates a change in the station configuration and a more vulnerable system. The failure of a related major component during a station preventive maintenance outage can result in a system disturbance and customer load loss. The bulk of the existing infrastructure of most electric power systems has been installed over the last 30 to 50 years. Aging failures of system components are a growing issue in modern electric power systems. Station related preventive maintenance outages and aging failures are important factors that affect the system reliability. This thesis examines the reliability implications of station related outages, including maintenance outages and aging outages in basic station configurations using two practical test systems. Models and techniques are created to incorporate these outages in composite system reliability evaluation. The techniques presented and the quantitative analyses illustrated in this thesis provide valuable information for a wide range of system planning, design, reinforcement and maintenance applications, including design and modification of power stations and station maintenance planning.

Multilayer embedded passives (resistors, inductors, and capacitors) on a printed wiring board can help to meet high performance requirements at a low cost and at a smaller size. Such an integration of embedded passives has new challenges with respect to design, materials, manufacturing, thermal management and reliability. As the area of integral passives on printed circuit boards is relatively new, there is inadequate literature on the thermo-mechanical reliability of integral passives. Therefore, there is a compelling need to understand the thermo-mechanical reliability of integral passives through the development of physics-based models as well as through experiments, and this thesis aims to develop such an experimental and theoretical program to study the thermo-mechanical reliability of integral passives.. As integral passives are often composite layers with dissimilar material properties compared to the other layers in the integral substrate, it is essential to ensure that RLC characteristics of the embedded passives do not deteriorate with thermal cycling due to thermo-mechanical deformations. This thesis aims to study the changes in the passive characteristics due to the thermally-induced deformations. Embedded capacitors and inductors have been looked at specifically in this research. Multi-field physics-based models have been constructed to determine the change in electrical parameters after thermal cycling. The thermo-mechanical models assume direction-dependent material properties for the board substrate and interconnect copper layers and temperature-dependent properties for interlayer dielectric and passive layers. Using the deformed geometry, the electrical characteristics have been determined at low frequency. In parallel to the models, test vehicle substrates have been subjected to 1000 thermal cycles between -55??o 125??nd high humidity and temperature conditions at 85??5RH for 500 hours, and it has been observed that there are significant changes in the electrical parameters. The results obtained from the physics-based simulations have been validated against the measured electrical characteristics from the fabricated functional test boards that have been thermal cycled.

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The objective of the research is to model the reliability and breakdown mechanism of back-end dielectrics in integrated circuits and to investigate the impact of physical design characteristics on the back-end dielectric reliability. As design and process complexities continue to increase, the reliability of the back-end dielectrics becomes marginal. This is mainly because the power supply voltage is not scaled at a rate comparable to feature size, which results in exponentially increasing electric fields among interconnect lines. Therefore, it is strongly desirable to be able to predict reliability or to detect design weaknesses to reliability failure during the pre-silicon verification stage. It is desirable to enable pre-silicon verification of back-end dielectric reliability based on physical design characteristics. In this research, it is shown that dielectric reliability can be modeled as a function of the critical circuit area based on the yield models. Defect clustering is taken into account by using the negative binomial statistics. The physical design characteristics will be investigated for their impact on back-end dielectric reliability. These characteristics include such factors as layout geometry, pattern density, pattern orientation, and via placement. The physical breakdown mechanism for porous back-end dielectric films is also to be investigated using Monte Carlo simulation. It is shown that the electric field is enhanced by porosity in ultra-low-k dielectric films. The electric field enhancement caused by the porosity is shown to accelerate the charge transport.

Renewable sources of energy such as wind turbine generators and solar panels have attracted much attention because they are environmentally friendly, do not consume fossil fuels, and can enhance a nation’s energy security. As a result, recently more significant amounts of renewable energy are being integrated into conventional power grids. The research reported in this dissertation primarily investigates the reliability-constrained planning and operations of electric power systems including renewable sources of energy by accounting for uncertainty. The major sources of uncertainty in these systems include equipment failures and stochastic variations in time-dependent power sources. Different energy sources have different characteristics in terms of cost, power dispatchability, and environmental impact. For instance, the intermittency of some renewable energy sources may compromise the system reliability when they are integrated into the traditional power grids. Thus, multiple issues should be considered in grid interconnection, including system cost, reliability, and pollutant emissions. Furthermore, due to the high complexity and high nonlinearity of such non-traditional power systems with multiple energy sources, computational intelligence based optimization methods are used to resolve several important and challenging problems in their operations and planning. Meanwhile, probabilistic methods are used for reliability evaluation in these reliability-constrained planning and design. The major problems studied in the dissertation include reliability evaluation of power systems with time-dependent energy sources, multi-objective design of hybrid generation systems, risk and cost tradeoff in economic dispatch with wind power penetration, optimal placement of distributed generators and protective devices in power distribution systems, and reliability-based estimation of wind power capacity credit. These case studies have demonstrated the viability and effectiveness of computational intelligence based methods in dealing with a set of important problems in this research arena.

This dissertation aims to address two optimization problems involving power system reliabilty analysis, namely multi-area power system adequacy planning and transformer maintenance optimization. A new simulation method for power system reliability evaluation is proposed. The proposed method provides reliability indexes and distributions which can be used for risk assessment. Several solution methods for the planning problem are also proposed. The first method employs sensitivity analysis with Monte Carlo simulation. The procedure is simple yet effective and can be used as a guideline to quantify effectiveness of additional capacity. The second method applies scenario analysis with a state-space decomposition approach called global decomposition. The algorithm requires less memory usage and converges with fewer stages of decomposition. A system reliability equation is derived that leads to the development of the third method using dynamic programming. The main contribution of the third method is the approximation of reliability equation. The fourth method is the stochastic programming framework. This method offers modeling flexibility. The implementation of the solution techniques is presented and discussed. Finally, a probabilistic maintenance model of the transformer is proposed where mathematical equations relating maintenance practice and equipment lifetime and cost are derived. The closed-form expressions insightfully explain how the transformer parameters relate to reliability. This mathematical model facilitates an optimum, cost-effective maintenance scheme for the transformer.

The demand for high performance microelectronic products drives the development of 3-D chip-stacking structure. By the introduction of through-silicon-via (TSV) into 3-D flip-chip packages, microelectronic performance is improved by increasing circuit capacity and diminishing signal delay. However, TSV-embedded structure also raises concerns over many reliability issues that come with the steep thermal and mechanical transient responses, increasing numbers of bi-material interfaces and reduced component sizes. In this research, defect initiation induced by thermalmechanical phenomena is studied to establish the early failure modes within 3-D flip-chip packages. It is found that low amplitude but extremely high frequency thermal stress waves would occur and attenuate rapidly in the first hundreds of nanoseconds upon power-on. Although the amplitude of these waves is far below material yielding points, their intrinsic characteristics of high frequency and high power density are capable of compromising the integrity of all flip-chip components. By conducting spectral analysis of the stress waves and applying the methodology of accumulated damage evaluation, it is demonstrated that micron crack initiation and interconnect debond are highly probable in the immediate proximity of the heat source. Such a negative impact exerted by the stress wave in the early, while brief, transient period is recognized as the short time scale dynamic effect. Researched results strongly indicate that short-time scale effects would inflict very serious reliability issues in 3-D flip-chip packages. The fact that 3-D flip-chip packages accommodate a large amount of reduced-size interconnects makes it vulnerable to the attack of short time scale propagating stress waves. In addition, the stacking structure also renders shearing effect extremely detrimental to 3-D flip-chip integrity. Finally, several guidelines effective in discouraging short-time scale effects and thus improving TSV flip-chip package reliability are proposed

In shipboard power systems (SPS), it is important to provide continuous power to vital loads so that their desired missions can be completed successfully. Several components exist between the primary source and the vital load such as transformers, cables, or switching devices. These components can fail due to mechanical stresses, electrical stresses, and overloading which could lead to a system failure. If the normal path to a vital load cannot supply power to it, then it should be powered through its alternate path. The process of restoring, balancing, and minimizing power losses to loads is called network reconfiguration. Prognostics is the ability to predict precisely and accurately the remaining useful life of a failing component. In this work, the prognostic information of the power system components is used to determine if reconfiguration should be performed if the system is unable to accomplish its mission. Each component will be analyzed using the Weibull Distribution to compute the conditional reliability from present time to the end of the mission. To determine if reconfiguration is needed, all components to a given load will be utilized in structure functions to determine if a load will be able to survive during a time period. Structure functions are used to show how components are interconnected, and also provide a mathematical means for computing the total probability of a system. This work will provide a method to compute the conditional survivability to a given load, and the results indicate the top five loads that have the lowest conditional survivability during a mission in known configuration. The results show the computed conditional survivability of loads on an all electric navy ship. The loads conditional survivability is computed on high/medium voltage level and a low voltage level to show how loads are affected by failing components along their path.

In this thesis, the dimension effects and reliabilities of the p-channel poly-Si TFTs for AMOLED are successfully characterized. We have measured and compared the electrical behaviors of devices to study dimension and temperature effects in this experiment. The influences on the narrow channel width effects are also discussed and explained. It is found that the devices with narrow channel width, exhibit promotional turn-on current and smaller threshold voltage. In addition, the stress effects in p-channel poly-silicon thin-film transistors are investigated and characterized with various applied voltages. The stress effects are clearly analyzed by different methods, such as activation energy of leakage current, changing the definition of source and drain for Vg-Id curve, and C-V measurements. Finally, a physical model was proposed to well explain the results we observed.

Abstract The study on SOC of article is one of package way for CSP. The SOC transmits messages by Solder Ball joining the board. It can make the volume of product decrease, but the reliability reduces on using. So the reliability of Solder Ball is a very important topic for study. The article for Solder Ball uses the Mixed-Viscoplastic way to simulate the warpage state of SOC when the temperature of Solder Ball rises by ANSYS. Then using the Viscoplastic material parameter simulates the acts by TCT experiment and checks the suitable Fatigue Model to get the analysis results turn into the reliability data. The reliability data puts to the proof with the experimental reliability data and compares differences to other documents.