FE IMPACTS ON SOLDER JOINT PROPERTIES IN MICROELECTRONIC ASSEMBLY

Master'sMASTER OF SCIENC

Corrosion Resistance

The book has covered the state-of-the-art technologies, development, and research progress of corrosion studies in a wide range of research and application fields. The authors have contributed their chapters on corrosion characterization and corrosion resistance. The applications of corrosion resistance materials will also bring great values to reader's work at different fields. In addition to traditional corrosion study, the book also contains chapters dealing with energy, fuel cell, daily life materials, corrosion study in green materials, and in semiconductor industry

In-situ health monitoring of IGBT power modules in EV applications

Power electronics are an enabling technology and play a critical role in the establishment of an environmentally-friendly and sustainable low carbon economy. The electrification of passenger vehicles is one way of achieving this goal. It is well acknowledged that Electric vehicles (EVs) have inherent advantages over the conventional internal combustion engine (ICE) vehicles owing to the absence of emissions, high efficiency, and quiet and smooth operation. Over the last 20 years, EVs have improved significantly in their system integration, dynamic performance and cost. It has attracted much attention in research communities as well as in the market. In 2011 electric vehicle sales were estimated to reach about 20,000 units worldwide, increasing to more than 500,000 units by 2015 and 1.3 million by 2020 which accounts for 1.8 per cent of the total number of passenger vehicles expected to be sold that year. In general, electric vehicles use electric motors for traction drive, power converters for energy transfer and control, and batteries, fuel cells, ultracapacitors, or flywheels for energy storage. These are the core elements of the electric power drive train and thus are desired to provide high reliability over the lifetime of the vehicle. One of the vulnerable components in an electric power drive train is the IGBT switching devices in an inverter. During the operation, IGBT power modules will experience high mechanical and thermal stresses which lead to bond wire lift-off and solder joint fatigue faults. Theses stresses can lead to malfunctions of the IGBT power modules. A short-circuit or open-circuit in any of the power modules may result in an instantaneous loss of traction power, which is dangerous for the driver and other road users. These reliability issues are very complex in their nature and demand for the development of analytical models and experimental validation. This work is set out to develop an online measurement technique for health monitoring of IGBT and freewheeling diodes inside the power modules. The technique can provide an early warning prior to a power device failure. Bond wire lift-off and solder fatigue are the two most frequently occurred faults in power electronic modules. The former increases the forward voltage drop across the terminals of the power device while the latter increase the thermal resistance of the solder layers. As a result, bond wire lift-off can be detected by a highly sensitive and fast operating in-situ monitoring circuit. Solder joint fatigue is detected by measuring the thermal impedance of the power modules. This thesis focuses on the design and optimisation of the in-situ health monitoring circuit in an attempt to reducing noise, temperature variations and measurement uncertainties. Experimental work is carried out on a set of various IGBT power modules that have been modified to account for different testing requirements. Then the lifetime of the power module can be estimated on this basis. The proposed health monitoring system can be integrated into the existing IGBT driver circuits and can also be applied to other applications such as industrial drives, aerospace and renewable energy.EThOS - Electronic Theses Online ServiceORSSchool of EEEGBUnited Kingdo

In-situ health monitoring of IGBT power modules in EV applications

Power electronics are an enabling technology and play a critical role in the establishment of an environmentally-friendly and sustainable low carbon economy. The electrification of passenger vehicles is one way of achieving this goal. It is well acknowledged that Electric vehicles (EVs) have inherent advantages over the conventional internal combustion engine (ICE) vehicles owing to the absence of emissions, high efficiency, and quiet and smooth operation. Over the last 20 years, EVs have improved significantly in their system integration, dynamic performance and cost. It has attracted much attention in research communities as well as in the market. In 2011 electric vehicle sales were estimated to reach about 20,000 units worldwide, increasing to more than 500,000 units by 2015 and 1.3 million by 2020 which accounts for 1.8 per cent of the total number of passenger vehicles expected to be sold that year. In general, electric vehicles use electric motors for traction drive, power converters for energy transfer and control, and batteries, fuel cells, ultracapacitors, or flywheels for energy storage. These are the core elements of the electric power drive train and thus are desired to provide high reliability over the lifetime of the vehicle. One of the vulnerable components in an electric power drive train is the IGBT switching devices in an inverter. During the operation, IGBT power modules will experience high mechanical and thermal stresses which lead to bond wire lift-off and solder joint fatigue faults. Theses stresses can lead to malfunctions of the IGBT power modules. A short-circuit or open-circuit in any of the power modules may result in an instantaneous loss of traction power, which is dangerous for the driver and other road users. These reliability issues are very complex in their nature and demand for the development of analytical models and experimental validation. This work is set out to develop an online measurement technique for health monitoring of IGBT and freewheeling diodes inside the power modules. The technique can provide an early warning prior to a power device failure. Bond wire lift-off and solder fatigue are the two most frequently occurred faults in power electronic modules. The former increases the forward voltage drop across the terminals of the power device while the latter increase the thermal resistance of the solder layers. As a result, bond wire lift-off can be detected by a highly sensitive and fast operating in-situ monitoring circuit. Solder joint fatigue is detected by measuring the thermal impedance of the power modules. This thesis focuses on the design and optimisation of the in-situ health monitoring circuit in an attempt to reducing noise, temperature variations and measurement uncertainties. Experimental work is carried out on a set of various IGBT power modules that have been modified to account for different testing requirements. Then the lifetime of the power module can be estimated on this basis. The proposed health monitoring system can be integrated into the existing IGBT driver circuits and can also be applied to other applications such as industrial drives, aerospace and renewable energy.EThOS - Electronic Theses Online ServiceORSSchool of EEEGBUnited Kingdo

Improved micro-contact resistance model that considers material deformation, electron transport and thin film characteristics

This paper reports on an improved analytic model forpredicting micro-contact resistance needed for designing microelectro-mechanical systems (MEMS) switches. The originalmodel had two primary considerations: 1) contact materialdeformation (i.e. elastic, plastic, or elastic-plastic) and 2) effectivecontact area radius. The model also assumed that individual aspotswere close together and that their interactions weredependent on each other which led to using the single effective aspotcontact area model. This single effective area model wasused to determine specific electron transport regions (i.e. ballistic,quasi-ballistic, or diffusive) by comparing the effective radius andthe mean free path of an electron. Using this model required thatmicro-switch contact materials be deposited, during devicefabrication, with processes ensuring low surface roughness values(i.e. sputtered films). Sputtered thin film electric contacts,however, do not behave like bulk materials and the effects of thinfilm contacts and spreading resistance must be considered. Theimproved micro-contact resistance model accounts for the twoprimary considerations above, as well as, using thin film,sputtered, electric contact

Belle II Technical Design Report

The Belle detector at the KEKB electron-positron collider has collected almost 1 billion Y(4S) events in its decade of operation. Super-KEKB, an upgrade of KEKB is under construction, to increase the luminosity by two orders of magnitude during a three-year shutdown, with an ultimate goal of 8E35 /cm^2 /s luminosity. To exploit the increased luminosity, an upgrade of the Belle detector has been proposed. A new international collaboration Belle-II, is being formed. The Technical Design Report presents physics motivation, basic methods of the accelerator upgrade, as well as key improvements of the detector.Comment: Edited by: Z. Dole\v{z}al and S. Un

Development and evaluation of a calibration free exhaustive coulometric detection system for remote sensing.

Most quantitative analytical measurement techniques require calibration to correlate signal with the quantity of analyte. The purpose of this study was to employ exhaustive coulometry, an implementation of coulometric analysis in a stopped-flow, fixed-volume, thin-layer cell, to attain calibration-free measurements that would directly benefit intervention-free analysis systems designed for remote deployment. This technique capitalizes on the short diffusion lengths (\u3c 100 µm) to dramatically reduce the time for analysis (\u3c 30 sec). For this work, a thin-layer fluidic cell was designed in software, fabricated via CNC machining, and evaluated using Ferri/Ferrocyanide {Fe(CN)63-/4-} as a model analyte. The 2 µL fixed volume incorporated an oval, 8mm by 4 mm, thin-film gold electrode sensor with an integrated Ag|AgCl pseudo-reference electrode. The flow cell area matched the shape of the sensor, with a volume set by the thickness of a laser-cut silicone rubber gasket (~80 µm). A semi-permeable membrane isolated the working electrode and counter electrode chambers to prevent analyte diffusion. A miniaturized custom potentiostat was designed and built to measure reaction currents ranging from 10 mA to 0.1 nA. Software was developed to perform step voltammetry as well as cyclic voltammetry analysis for verifying electrode condition and optimal redox potential levels. Experimentally determined oxidation/reduction potentials of -100 mV and 400 mV, respectively, were applied to the working electrode for sample concentrations ranging from 50 µM to 10,000 µM. The current generated during the reactions was recorded and the total charge captured at each concentration was obtained by integrating the amperograms. When compared to the expected charge for a 2 µL sample, the total charge vs. concentration plots displayed a near perfect linearity over the full concentration range, and the expected charge (100 % converted) was reached within 20 seconds. The reaction currents ideally should have decayed to background levels, but exhibited constant offset values slightly larger than the background signal, a phenomenon assumed to be lingering residual flow from sample injection. After adding rigid tubing and external valves, the thin-layer cell was shown to remain within 6% of the theoretical charge after 200 seconds. Continued development of this system will offer the possibility of remote, calibration-free determinations of real-world analytes such mercury and lead

The design and evaluation of discrete wearable medical devices for vital signs monitoring

The observation, recording and appraisal of an individual’s vital signs, namely temperature, heart rate, blood pressure, respiratory rate and blood oxygen saturation (SpO2), are key components in the assessment of their health and wellbeing. Measurements provide valuable diagnostic data, facilitating clinical diagnosis, management and monitoring. Respiratory rate sensing is perhaps the most under-utilised of all the vital signs, being routinely assessed by observation or estimated algorithmically from respiratory-induced beat-to-beat variation in heart rate. Moreover there is an unmet need for wearable devices that can measure all or most of the vital signs. This project therefore aims to a) develop a device that can measure respiratory rate and b) develop a wearable device that can measure all or most of the vital signs. An accelerometer-based clavicular respiratory motion sensor was developed and compared with a similar thoracic motion sensor and reference using exhalatory flow. Pilot study results established that the clavicle sensor accurately tracked the reference in monitoring respiratory rate and outperformed the thoracic device. An Ear-worn Patient Monitoring System (EPMS) was also developed, providing a discrete telemonitoring device capable of rapidly measuring tympanic temperature, heart rate, SpO2 and activity level. The results of a comparative pilot study against reference instruments revealed that heart rate matched the reference for accuracy, while temperature under read (< 1°C) and SpO2 was inconsistent with poor correlation. In conclusion, both of the prototype devices require further development. The respiratory sensor would benefit from product engineering and larger scale testing to fully exploit the technology, but could find use in both hospital and community-based The design and evaluation of discrete wearable medical devices for vital signs monitoring DG Pitts ii Cranfield University monitoring. The EPMS has potential for clinical and community use, having demonstrated its capability of rapidly capturing and wirelessly transmitting vital signs readings. Further development is nevertheless required to improve the thermometer probe and resolve outstanding issues with SpO2 readings

Semiannual review of research and advanced development, 1 January - 30 June 1969. Volume 2 - /OART/

Supporting research and technology on spacecraft propulsion and electronic system