Effect of stand‑of height on the shear strength of ball grid array solder joints under varying pad sizes

The solder joints of ball grid array utilized in consumer electronics systems or assemblies degrade and fail overtime. Their degree of degradation is more critical, especially at elevated temperatures and mechanical loading conditions. This study presents the efect of component standof height (CSH) on the shear strength reliability of ball grid array solder joints under diferent pad sizes. Investigation of the impact of standof height on the mechanical reliability of the solder joint of ball grid array components under diferent pad sizes was conducted in this work. Isothermal ageing of test samples were conducted at 150 °C for 8 days. This study focuses on establishing the relationship between CSH and shear strength of the solder joints under diferent pad sizes and the corresponding efect of prolonged elevated temperature conditions on the mechanical integrity of the soldered joints. The work also identifes the failure mode and examines the region of the failed joints and surfaces to provide information on the morphological characteristics of the material microstructure. The results of this study demonstrate that the smallest pad size (19 mil) gave the lowest shear strength of 61.08 MPa with a high standof height of 0.25 mm as compared to the largest pad size (24 mil) with the highest shear strength of 70.43 MPa having a relatively low standof height of 0.22 m

Pathways for the Valorization of Animal and Human Waste to Biofuels, Sustainable Materials, and Value-Added Chemicals

Human and animal waste, including waste products originating from human or animal digestive systems, such as urine, feces, and animal manure, have constituted a nuisance to the environment. Inappropriate disposal and poor sanitation of human and animal waste often cause negative impacts on human health through contamination of the terrestrial environment, soil, and water bodies. Therefore, it is necessary to convert these wastes into useful resources to mitigate their adverse environmental effect. The present study provides an overview and research progress of different thermochemical and biological conversion pathways for the transformation of human- and animal-derived waste into valuable resources. The physicochemical properties of human and animal waste are meticulously discussed, as well as nutrient recovery strategies. In addition, a bibliometric analysis is provided to identify the trends in research and knowledge gaps. The results reveal that the USA, China, and England are the dominant countries in the research areas related to resource recovery from human or animal waste. In addition, researchers from the University of Illinois, the University of California Davis, the Chinese Academy of Sciences, and Zhejiang University are front runners in research related to these areas. Future research could be extended to the development of technologies for on-site recovery of resources, exploring integrated resource recovery pathways, and exploring different safe waste processing methods

Pathways for the Valorization of Animal and Human Waste to Biofuels, Sustainable Materials and Value-Added Chemicals

Human and animal waste, including waste products originating from human or animal digestive systems such as urine, feces, and animal manure, have constituted a nuisance to the environment. Inappropriate disposal and poor sanitation of human and animal waste often cause negative impacts on human health through contamination of the terrestrial environment, soil, and water bodies. Therefore, it is necessary to convert these wastes into useful resources to mitigate their adverse environmental effect. The present study provides an overview and research progress of different thermochemical and biological conversion pathways for the transformation of human- and animal-derived waste into valuable resources. The physicochemical properties of human and animal waste are meticulously discussed as well as nutrient recovery strategies. In addition, a bibliometric analysis is provided to identify the trends in research and knowledge gaps. The results reveal that the U.S.A, China and England are the dominant countries in the research areas related to resource recovery from human or animal waste. In addition, researchers from the University of Illinois, the University of California Davis, the Chinese Academy of Science and Zhejiang University are front runners in research related to these areas. Future research should be centred on developing technologies for the on-site recovery of resources, exploring integrated resource recovery pathways, and exploring different safe waste processing methods

A review of ceramic/bio-based hybrid reinforced aluminium matrix composites

The quest for light and durable materials which can withstand harsh conditions of modern advanced applications in many fields such as aviation, automobile, sport, and so on, has been scientifically sought for. Studies in the last few decades have found aluminium metal composites (AMCs) reinforced with bio-based fibres of diverse origins as a suitable advanced material because of improved physical and mechanical properties that are obtainable. Such reinforcements may be single (usage of one reinforcement) or hybridized (more than one reinforcement) with synthesized particulate materials; however, they impart better physico-mechanical and wear behavior on the aluminium alloy matrix. Thus, this review examines some of these composites produced by stir-casting procedures and their properties currently trending in materials research circles. It has been established that by varying parameters such as stirring speed/time and reinforcement types and composition, the use of stir casting process is a viable method to produce AMCs with good physical properties, mechanical properties, and wear behavior. AMCs are eminently useful in the production of parts for the automotive, aerospace and aviation industries

TIG Welding of Ti6Al4V: Effect of Ti6Al4V ELI as Filler Metal

Titanium and its alloys have significant uses in the biomedical, chemical, and aerospace industries. In this article, the current and gas flow rates were varied using Taguchi’s experiment design. The mechanical properties of the welded joint made using tungsten inert gas (TIG) welding and Ti6Al4V ELI as filler metal was characterized using the microstructure, microhardness, and tensile strength. The joint was classified into three regions, namely, fusion zone (FZ), heat affected zone (HAZ), and base metal (BM). Results show martensitic microstructure within the fusion zone (FZ) and the heat affected zone (HAZ), which resulted in an increased hardness within the fusion and heat affected zone

Scanning and transmission electron microscopy examinations of composite hybrid chromate and chromate phosphate conversion coatings exposed in hot 100% relative humidity environments

Conversion coatings are sine qua non in the finishing of aluminium alloys. They may be put into service without coating of paints. However, for aesthetics in architectural applications, paint overcoat is common. Chromate phosphate coatings are relatively less toxic than chromate which gained the pride of place until recently. Thus, aluminium specimens coated with hybrid chromate/phosphate conversion coatings have been subjected to 100% relative humidity for 480 h at 313K in comparison to chromate coatings and bare aluminium. Scanning electron microscopy examination revealed that initial dried river bed morphologies on coated specimens were obliterated. The friable outer coatings collapsed into the cracks/environment leaving a relatively smooth surface after exposure. Additionally, transmission electron microscopy of sections before and after exposure revealed similar texture and morphological striations nearly parallel to each other throughout the length of the coatings to the metal/coating interface. These were not disrupted as well as the metal/coating interface which remained relatively smooth with no visible corrosion products after exposure. Thus, the coatings formed effective barrier between the substrate and the relatively harsh environment. From EDS, elemental compositions were the same albeit, spectral intensities remained relatively constant after humidity exposure regimes. The coatings are made up of either Cr, O and Al for chromate and Cr, P, O and Al for chromate/phosphate. At deliberately breached regions, the coatings prevented spread of corrosion and paint delamination over the substrates. On the other hand, bare aluminium was decorated with mounds of hydrated aluminium oxide/hydroxide after exposure as revealed in the SEM/TEM

Applicability of Industrial Wastes in Metal Matrix Composites Production – A Review

The review study is to investigate the possibility of utilizing industrial waste materials as a strengthening component in the manufacturing of metal-matrix composites (MMCs) and assess the associated environmental benefits. The study focused on examining two distinct sets of waste materials: metal matrix composites that were reinforced with fly ash, and composites produced from different kinds of industrial waste materials. Technical and property-related data were reviewed to evaluate the potential of these waste materials in MMC production. The study results indicated that fly ash-reinforced metal-matrix composites exhibited exceptional physical and mechanical properties, which make them well-suited for various applications, particularly in the automotive sector. The research highlights the necessity for further studies to innovate advanced materials with improved properties while mitigating environmental pollution. Overall, the research demonstrates the potential of utilizing industrial waste materials as reinforcement in MMC production and underscores the importance of this approach for the future development of advanced materials

Physico-chemical characterization, thermal decomposition and kinetic modeling of Digitaria sanguinalis under nitrogen and air environments

The study undertook the thermal degradation of a tropical grass species, Digitaria sanguinalis, in nitrogen (pyrolysis) and air (combustion) atmospheres through thermogravimetric analysis as well as comparative kinetic investigation. The differential (Friedman) and integral (Flynn-Wall-Ozawa and Straink) isoconversional methods in conjunction with the Coats-Redfern method were utilized. This was to obtain the kinetic parameters and also predict the probable reaction mechanisms involved in the decomposition process. Before the thermal and kinetic investigations, the grass was analyzed for its physical, chemical, and structural properties utilizing diverse wet-chemistry and spectroscopic techniques. This research attempt is part of a larger project designed to investigate a couple of local grass species, which are invasive by nature, as potential energy crops for pyrolytic and combustion applications. The grass had a fixed carbon content of 17.85% and a calorific value of 13.7 MJ kg−1. The fatty acids detected were from C12 (lauric acid) to C24 (lignoceric acid), with the three most abundant being palmitic (94 mg/g extract), linoleic (27 mg/g extract), and oleic (19 mg/g extract) acids. The average residual weight in air (25.3%) was relatively less than in nitrogen (38.7%), affirming the higher rate of reaction in an oxidative process (combustion). The activation energy profiles in both atmospheres were markedly different, as shown by the Flynn-Wall-Ozawa technique for a conversion ratio of 0.1–0.2 (nitrogen, 149 kJ/mol; air, 177 kJ/mol) and 0.65–0.8 (nitrogen, 366 kJ/mol; air, 170 kJ/mol). Of all the models tested, the model-fitting technique indicates that the chemical reaction and diffusional models play predominant roles in the thermal decomposition of the grass under investigation. The thermal degradation of Digitaria sanguinalis proceeded mainly as complex multi-step reaction mechanisms. Aside from the potential suitability of the grass species for bioenergy applications and biofuels production, it also demonstrated huge capability for biochemical extraction. Future work will incorporate the kinetic data for the associated thermochemical processes development, and the design and optimization of reactors/combustors

Assessing absorption-based CO2 capture: Research progress and techno-economic assessment overview

Rapid industrial developments and rising population are mounting concerns, leading to increased greenhouse gas (GHG) emissions and resultant climate change. Therefore, to curb such drastic trends, it is necessary to adopt and develop a sustainable environment. Among the most effective ways to lower GHG emissions is carbon capture. Absorption is one of the most mature methods of reducing CO2 due to its high processing capacity, excellent adaptability, and reliability. This study aims to evaluate the most recent advancements in various CO2 capture techniques, with an emphasis on absorption technology. The techno-economic analyses of absorption-based CO2 capture processes were meticulously discussed. These include studies on solvent screening as well as techno-economic analysis methods. Economic estimators such as the payback period, rate of return and net present value are discussed. The research progress in absorption-based capture compared to other separation methods, is elucidated. Advances in the applications of various absorption solvents including aqueous, phase change solvents and deep eutectic solvents are presented. Finally, key recommendations are provided to tackle the challenges for efficient utilization of the absorption technique