Abstract The effect of joint strength of PbSn and AuSn solder on temperature cycling tests in laser packages has been studied experimentally and numerically. It was found that the solder joint strength increased as temperature cycle number increased, and then became steady after 400 cycles. This is may be due to the redistribution of the residual stresses within the solder during temperature cycling test, and hence reducing the residual stresses and increasing the solder joint as the temperature cycle increased. Numerical calculations were in good agreement with the experimental measurement that the solder joint strength increased as the temperature cycle increased. In this work, we also study the intermetallic compound (IMC) growth of PbSn and AuSn solders under cycling test and aging test. The thickness of IMC growth do not significantly increase under cycling test, because the cycling test temperature was from ¡V40 to 85ºC. However, under the high temperature aging of 200ºC for 25 days, the IMC thickness was increased to 4.71£gm.

Abstract Accompany a rapid growth in the semiconductor industry in the past few year, most components gradually used the small dimension as its basic structures. Due to the reduction of component size will induces highly concentrated on circuit and dimension, it also incurs a lots problem, such as electromagnetic interference, high temperature and thermal stress, which will decrease the product reliability. The most common damage in the semiconductor product is thermal fatigue, which is caused by thermal stress concentrated under repeatedly temperature variation loading. Usually, the thermal cycle loading is applied to induce the fatigue destruction and predict the product reliability, but this method spends one cycle for 80min which is time-consumption. Therefore, in this thesis, the finite element method package is used to simulate and evaluate the plastic variation of solder bump and the relation between different temperatures loading and equivalent plastic strain under different temperature range test. Through the Coffin-Manson equation, the equivalent plastic strain can be used to predict the fatigue live, which can be precisely accelerating the fatigue test.

The solvent 7 molal (m) methyldiethanolamine (MDEA)/2 m piperazine (PZ) presents an attractive option to industry standard solvents including monoethanolamine (MEA) for carbon dioxide (CO₂) capture in coal-fired power plant flue gas scrubbing applications. The solvent was tested under thermal and oxidizing conditions, including temperature cycling in the Integrated Solvent Degradation Apparatus (ISDA), to measure rates of degradation for comparison to other solvents. Unloaded 7 m MDEA/2 m PZ was generally thermally stable up to 150 °C, exhibiting very low loss rates. However, at a loading of 0.25 mol CO2/mol alkalinity, loss rates of 0.17 ± 0.21 and 0.24 ± 0.06 mM/hr, respectively, for MDEA and PZ were measured. No amine loss was observed in the unloaded blend. Thermal degradation was modeled as first-order in [MDEAH⁺], and a universal Ea for amine loss was estimated at 104 kJ/mol. An oxidative degradation model for 7 m MDEA was developed based on the ISDA data. From the model, the rate of amine loss in 7 m MDEA/2 m PZ was estimated at 1.3 X 10⁵ kg/yr, based on a 500 MW power plant and 90% CO₂ capture. In terms of amine loss, the solvent can be ranked with other cycled solvents from greatest to least as follows: 7 m MDEA>7 m MDEA/2 m PZ>8 m PZ. Thermal degradation pathways and mechanisms for 7 m MDEA/2 m PZ include SN2 substitution reactions to form diethanolamine (DEA), methylaminoethanol (MAE), 1-methylpiperazine (1-MPZ), and 1,4-dimethylpiperazine (1,4-DMPZ). The formation of the amino acids bicine and hydroxyethyl sarcosine (HES) has been directly tied to the formation of DEA and MAE, respectively, through oxidation. As a result of the construction and operation of the ISDA for cycling of solvents from an oxidative reactor to a thermal reactor, several practical findings related to solvent degradation were made. The ISDA results demonstrated that increasing dissolved oxygen in solvents leaving the absorber will increase the rate of oxidation. A simple N2 gas stripping method was tested and resulted in a reduction to 1/5th the high temperature oxidation rate associated with dissolved oxygen present in the higher temperature regions of an absorber/stripper system. The ISDA experiments also demonstrated the need to minimize entrained gas bubbles in absorber/stripper systems to control oxidation. When the ISDA was modified to intercept entrained gas bubbles, the oxidation rate was reduced 2 to 3X. / text

Mercury (Hg) is a potent human toxin and a persistent global pollutant with unique properties and environmental behaviours which make it difficult to model and understand. While anthropogenic mercury sources are well understood along with the impacts on ecosystems and human populations, the processes and transformations which govern environmental cycling lack the same level of understanding. Concentrations in Arctic environments are a specific concern, along with cycling behaviours in regions spanning from temperate to Arctic climates. The objective of this experiment was the investigation and characterization of the mechanisms which promote elemental mercury (Hg^0) flux from soils in these environments during simulated seasonal cycling. A laboratory scale experiment was conducted which used a Dynamic Flux Chamber (DFC) to monitor Hg^0 flux from a naturally Hg enriched soil during temperature cycling relevant to cold environments. The results, which were split into freeze-thaw (FT) and sub-zero (SZ) cycles, showed that Hg^0 flux from frozen soils remains active during temperature cycling. During FT cycles, Hg^0 flux is controlled by soil temperature and energy entering the system, with a linear increase in flux for increases in energy. This response is produced from the entire soil column. During SZ cycles, Hg^0 flux is produced only in the thin soil surface layer and is controlled by the air temperature at the soil-air interface. A decrease in the DFC air temperature was observed to produce an increase in flux, with an inverse relationship controlled by a separate mechanism than the FT cycle response. Recommendations for modifications to the experimental set-up and methodology have been made to improve the accuracy of the results and confirm the behaviours characterized during this study. / Natural Sciences and Engineering Research Council of Canada (NSERC)

>Magister Scientiae - MSc / Polymer electrolyte membrane fuel cells (PEMFCs) among other fuel cells are considered the best candidate for commercialization of portable and transportation applications because of their high energy conversion and low pollutant emission. Recently, there has been significant interest in high temperature polymer electrolyte membrane fuel cells (HT-PEMFCs), due to certain advantages such as simplified system and better tolerance to CO poisoning. Cost, durability and the reliability are delaying the commercialization of PEM fuel cell technology. Above all durability is the most critical issue and it influences the other two issues. The main objective of this work is to study the durability of membrane electrode assemblies (MEAs) for HT-PEMFC. In this study the investigation of commercial MEAs was done by evaluating their performance through polarization studies on a single cell, including using pure hydrogen and hydrogen containing various concentrations of CO as fuel, and to study the performance of the MEAs at various operating temperatures. The durability of the MEAs was evaluated by carrying out long term studies with a fixed load, temperature cycling and open circuit voltage degradation. Among the parameters studied, significant loss in the performance of the MEAs was noted during temperature cycling. The effect of temperature cycling on the performance of the cell showed that the performance decreases with increasing no. of cycles. This could be due to leaching of acid from the cell or loss of electrochemically active surface area caused by Pt particle size growth. For example at 160°C, a performance loss of 3.5% was obtained after the first cycle, but after the fourth cycle a huge loss of 80.8% was obtained. The in-house MEAs with Pt-based binary catalysts as anodes were studied for CO tolerance, performance and durability. A comparison of polarization curves between commercial and in-house MEAs illustrated that commercial MEA gave better performance, obtaining 0.52 A/cm² at 0.5V and temperature of 160°C, with in-house giving 0.39A/cm² using same parameters as commercial. The CO tolerance of both commercial and in-house MEA was found to be similar. In order to increase the CO tolerance of the in-house MEAs, Pt based binary catalysts were employed as anodesand the performance was investigated In-house MEAs with Pt/C and Pt-based binary catalysts were compared and a better performance was observed for Pt/C than Pt-alloy catalysts with Pt-Co/C showing comparable performance. At 0.5 V the performance obtained was 0.39 A/cm2 for Pt/C, and 0.34A/cm²,0.28A/cm²,0.27A/cm² and 0.16A/cm² were obtained for Pt-Co/C, Pt-Fe/C, Pt-Cu/C and Pt-Ni respectively. When the binary catalysts were tested for CO tolerance, Pt-Co showed no significant loss in performance when hydrogen containing CO was used as anode fuel. Scanning electron microscopy (SEM) revealed delamination between the electrodes and membrane of the tested and untested MEA's. Membrane thinning was noted and carbon corrosion was observed from the tested micro-porous layer between the gas diffusion layer (GDL) and catalyst layer (CL).

This thesis aims to provide insight into the fundamental electrochemical processes taking place when cycling SnO2 in lithium-ion batteries (LIBs). Special attention was paid to the partial reversibility of the tin oxide conversion reaction and how to enhance its reversibility. Another main effort was to pinpoint which limitations play a role in tin based electrodes besides the well-known volume change effect in order to develop new strategies for their improvement. In this aspect, Li+ mass transport within the electrode particles and the large first cycle charge transfer resistance were studied. Li+ diffusion was proven to be an important issue regarding the electrochemical cycling of SnO2. It was also shown that it is the Li+ transport inside the SnO2 particles which represents the largest limitation. In addition, the overlap between the potential regions of the tin oxide conversion and the alloying reaction was investigated with photoelectron spectroscopy (PES) to better understand if and how the reactions influence each other`s reversibility. The fundamental insights described above were subsequently used to develop strategies for the improvement of the performance and the cycle life for SnO2 electrodes in LIBs. For instance, elevated temperature cycling at 60 oC was employed to alleviate the Li+ diffusion limitation effects and, thus, significantly improved capacities could be obtained. Furthermore, an ionic liquid electrolyte was tested as an alternative electrolyte to cycle at higher temperatures than 60 oC which is the thermal stability limit for the conventional LP40 electrolyte. In addition, cycled SnO2 nanoparticles were characterized with transmission electron microscopy (TEM) to determine the effects of long term high temperature cycling. Also, the effect of vinylene carbonate (VC) as an electrolyte additive on the cycling behavior of SnO2 nanoparticles was studied in an effort to improve the capacity retention. In this context, a recently introduced intermittent current interruption (ICI) technique was employed to measure and compare the development of internal cell resistances with and without VC additive.

This study focused on the development and evaluation of die-attach material and substrate technology for high-temperature applications. For the die-attach material, a low-temperature sintering technique enabled by a nanoscale silver paste was developed for attaching large-area (>100 mm2) semiconductor chips. The nanoscale silver paste can be sintered at a much lower temperature (<300 oC) than in the conventional sintering process (>800 oC), and at the same time reached about 80 vol% bulk density. Analyses of the sintered joints by scanning acoustic imaging and electron microscopy showed that the attachment layer had a uniform microstructure with micron-sized porosity with the potential for high reliability under high temperature applications. We also investigated the effects of a large temperature cycling range on the reliability of direct bonded aluminum (DBA) substrate. DBA substrates with different metallization were thermally cycled between -55 oC and 250 oC. Unlike with the DBC substrate, no delamination of aluminum from the aluminum nitride ceramic base-plate was observed for the DBA substrates. However, aluminum surface became roughened during the thermal cycling test. It was believed that in the high-temperature regime, the significant amount of thermomechanical stress and grain-scale deformation would cause recrystallization and grain-boundary sliding in the aluminum layer, which would further lead to the observed increase in surface roughness. The influence of metallization over the aluminum surface on the extent of surface roughness was also characterized. In addition to evaluating the reliability of nanoscale silver paste and DBA substrate individually, this work also conducted experiments that characterize the compatibility of nanoscale silver paste on DBA substrate in terms of reliability in a high-temperature environment. In the large-area attachment, the sintered silver was found to be very compliant with the deformed aluminum. The device-to-silver and silver-to-substrate interfaces remain intact after up to 800 cycles. No large scale delamination and horizontal cracks were observed. However, some vertical crack lines began to show after certain number of cycles. It was believed that these vertical cracks were caused by the thermomechanical stresses in the sintered silver layer. In addition, with regard to the thermal performance, since most of the heat was generated from the semiconductor devices and were transferred vertically through the die-attach material to substrate, these vertical cracks were also considered more advantageous than horizontal cracks. / Ph. D.

Les accumulateurs lithium-ion occupent aujourd’hui une place prédominante dans le domaine du stockage de l’énergie. Leur fonctionnement et les phénomènes impliqués dans leur vieillissement sont relativement bien connus, aux températures d’utilisation proches de la température ambiante. Cependant, leur utilisation dans le cadre d’applications dites « haute température », telles que le forage pétrolier, la stérilisation « in situ » ou la géolocalisation, nécessite la levée de certains verrous techniques : la stabilité de l’électrolyte et des liants d’électrodes, la compatibilité électrolyte/séparateur, le vieillissement des matériaux et l’évolution des interfaces. Les accumulateurs sélectionnés pour ces travaux de thèse sont constitués d’un matériau lamellaire de type Li(Ni,Mn,Co)O2 pour l’électrode positive, et de graphite pour l’électrode négative. Afin de décrire les phénomènes de vieillissement associés à une telle utilisation, des analyses de surface ont été menées par Spectroscopie Photoélectronique à rayonnement X sur les électrodes issues d’accumulateurs cyclés à haute température. Ces analyses ont permis de mettre en évidence la dégradation du liant de l’électrode positive et l’évolution des interfaces électrodes/électrolyte à 85 et 120°C, et d’améliorer le choix des composants des batteries pour de meilleures performances à haute température. / Nowadays, lithium-ion batteries occupy a prominent place in the field of energy storage. Phenomena involved in their aging mechanisms are quite well known for operating temperatures close to room temperature. However, their use at high temperatures for applications such as oil drilling, "in situ" sterilization or freight tracking requires some technical issues to be improved: stability of the electrolyte and electrode binders, compatibility electrolyte / separator, aging of active materials and changes of the interfaces. The batteries selected for this thesis consist of a Li(Ni,Mn,Co)O2 lamellar material at the positive electrode and graphite at the negative electrode. To describe aging phenomena related to high temperature, surface analyzes were carried out by X-ray Photoelectron Spectroscopy on the electrodes of batteries cycled at 85 and 120°C. These analyzes reveal the degradation of the positive electrode’s binder, and the changes of electrodes/electrolyte’s interfaces at high temperature compared to ambient temperature.

Many cutting-edge computer and electronic products are powered by advanced Systems-on-Chip (SoC). Advanced SoCs encompass superb performance together with large number of functions. This is achieved by efficient integration of huge number of transistors. Such very large scale integration is enabled by a core-based design paradigm as well as deep-submicron and 3D-stacked-IC technologies. These technologies are susceptible to reliability and testing complications caused by thermal issues. Three crucial thermal issues related to temperature variations, temperature gradients, and temperature cycling are addressed in this thesis. Existing test scheduling techniques rely on temperature simulations to generate schedules that meet thermal constraints such as overheating prevention. The difference between the simulated temperatures and the actual temperatures is called temperature error. This error, for past technologies, is negligible. However, advanced SoCs experience large errors due to large process variations. Such large errors have costly consequences, such as overheating, and must be taken care of. This thesis presents an adaptive approach to generate test schedules that handle such temperature errors. Advanced SoCs manufactured as 3D stacked ICs experience large temperature gradients. Temperature gradients accelerate certain early-life defect mechanisms. These mechanisms can be artificially accelerated using gradient-based, burn-in like, operations so that the defects are detected before shipping. Moreover, temperature gradients exacerbate some delay-related defects. In order to detect such defects, testing must be performed when appropriate temperature-gradients are enforced. A schedule-based technique that enforces the temperature-gradients for burn-in like operations is proposed in this thesis. This technique is further developed to support testing for delay-related defects while appropriate gradients are enforced. The last thermal issue addressed by this thesis is related to temperature cycling. Temperature cycling test procedures are usually applied to safety-critical applications to detect cycling-related early-life failures. Such failures affect advanced SoCs, particularly through-silicon-via structures in 3D-stacked-ICs. An efficient schedule-based cycling-test technique that combines cycling acceleration with testing is proposed in this thesis. The proposed technique fits into existing 3D testing procedures and does not require temperature chambers. Therefore, the overall cycling acceleration and testing cost can be drastically reduced. All the proposed techniques have been implemented and evaluated with extensive experiments based on ITC’02 benchmarks as well as a number of 3D stacked ICs. Experiments show that the proposed techniques work effectively and reduce the costs, in particular the costs related to addressing thermal issues and early-life failures. We have also developed a fast temperature simulation technique based on a closed-form solution for the temperature equations. Experiments demonstrate that the proposed simulation technique reduces the schedule generation time by more than half.

This thesis is considered about interconnect PCB with microelectronic and electronic modules and continuing on thesis MODERN CAUSES OF ASSEMBLY MICROELECTRONICS AND ELECTRONICS MODULES. This thesis includes, definition of termomechanical strain in solder joints and description of LTCC technology. Practical part includes characterization the causes of assembly with usage chip component and proposal footprint for PCBs, modules and results of temperature cycling of tested modules.