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Polyethylene (PE) and oil impregnated paper are widely used as insulation materials in high voltage power equipment however, at high voltages the space charge inside the insulating material can distort the electric field distribution and thus greatly influence aging and degradation. Moreover, there is usually a temperature gradient across the insulation when the equipment is in service, and this can...
A novel SiC doped SAC305 composite solder was developed by mechanically mixing various amount of the SiC whiskers with Sn-3.0Ag-0.5Cu solder paste. The effect of SiC whiskers addition on microstructure, microhardness and wettability of the composite solders was investigated. It was found that the eutectic structure was refined in the composite solder, and both of the microhardness and wettability...
Electronic assembly technology is in the transition from traditional tin-lead to lead-free. In comparison with Sn-Pb solders, high melting point and poor wettability of the lead-free solders lead to great challenge in many aspects. It has been accepted that inert N2 atmosphere can improve the wettability and reliablity of solder joints. The focus of this study is to investigate the reliability of...
Sn-3.5Ag nanosolder in tiny sizes can provide a practical way to solve the high soldering temperature problem of lead-free solder alloy in fine pitch interconnectivity owing to the unique nanosize effect and meantime stand a higher working temperature just as the bulk material after welding. In this paper, a simple approach to synthesis Sn-3.5Ag nanoparticles by chemical reduction at room temperature...
In this paper, the recent two years of failure analysis cases of our laboratory are screened and some of them are displayed, they are mostly selected with a relation to the influence of temperature and humidity. To illustrate the typical and common failure phenomenon, plastic packaging products are focused. The main failure mode of these failed products include package delaminations, solder abnormality,...
Since the 50Sn32Pb18Cd eutectic solder was melted at 145 °C which is lower than the melting point of 63Sn37Pb solder (183 °C), it was selected as the interconnection joint to create a temperature gradient to avoid the former nearby 63Sn37Pb joint re-melted during the components assembly process. The tensile testing and the microstructure analysis were carried out on 50Sn32Pb18Cd eutectic solder to...
Lead-free solder alloys are more easily oxygenized and have poor wettability compared to traditional Sn-Pb solder alloys, which affects solder joints reliability. Ar is the most plentiful rare inert gas. It has been accepted that, in Ar atmosphere, the oxidation of lead-free solder joints can be prevented and the wettability of lead-free solder joints can be improved. To date, however, few systemic...
The following study is motivated by the need to capture the elasto-viscoplastic behavior of a “real” industrial power module lead-free solder joint. In this work, we carried out a numerical design of experiments in order to forecast the ability of an experimental bending system to identify the specimen material properties. As a proof of principle, the micro-mechanical elastic behavior of power module...
Organizational ambidexterity, defined as the simultaneously pursuit of both exploitation and exploration activities, is essential for organizations' survival, thrive and mature. However, the building of this capability is still ambiguous in prior literatures. This paper draws on the organizational learning theories, presents how two types of learning (i.e. strategic learning and business learning)...
Filter networks consisting of a Multi Layer Ceramic Capacitor and maybe a resistor are commonly used as off-chip ESD-protection. In this paper methods are proposed to characterize and model the capacitor's high voltage behavior and to quantify the degradation due to pulse load. The model was verified in different setups.
Study of remote sensed imagery has gained practical significance in various domains such as environmental monitoring, fire risk mapping, change detections and land use. Classification is a data mining methodology which is used to assign class labels to data instances and build a model so as to be able to predict class labels for unlabelled data. In this paper algorithms based on parametric distribution...
In this paper, the effect of the various thickness of the solder joint between the SMD (Surface Mound Device) chip resistor and the PCB (Printed Circuit Board) pad on the mechanical strength was investigated with FEM (Finite Element Method) simulation. The mechanical effect was studied for different solder alloys too; lead-free and lead-bearing alloys were compared together. A FEM program was used...
Emergent order in complex dynamic systems is a concept that is both important to a wide variety of fields of science and difficult to understand and teach. Recent advancements in interactive and tangible interfaces point towards the possibility of new tools which can help with both the analysis and simulation of complex systems, while also making the systems dynamics more approachable and easier to...
The whisker formation behaviors of Sn3.0Ag0.5Cu composite solder which reinforced by an organic-inorganic hybrid materials, silanol of polyhedral oligomeric silsesquioxane (POSS-silanol) was investigated. The thin solder films were obtained by reflow soldering and a thermal cycle from −40°C to +85°C was applied to accelerate the test process. Both surface and interface microstructures of the specimens...
With the introduction of relevant laws and regulations in many countries, the electronic industry around the global has switched into lead-free age because of the harm of lead in solder on the environment and human health,. SnAgCu based solder is the most popular lead-free solder recently. The solder joint reliability has become an increasingly problem due to the change of packaging materials and...
QFN (Quad Flat No-lead) packages become popular in recent years because they provide many advantages over conventional leadframe packages. Due to CTE (Coefficient of Thermal Expansion) mismatch of different materials applied in the package, significant warpage will be generated during QFN packaging process, and may cause yield and reliability issues. In this paper, the warpage of a QFN strip induced...
α-Sn seed was preset on the surface of both the high purity tin (99.999%) and Sn-0.7%Cu ingots, then the samples were kept at −40 V for different times, the surface morphology of the samples was observed to study the process of the β/α transformation. SEM was used to evaluate the degree of the phase transition, while the XRD was applied to identify the product of the transformation The results showed...
In this study, the pattern of institution of execution is divided into two types, one is institutional determined which means results were determined by institution, and the other is authority determined which means results were determined by authority's decision. The study examines the influence of two institutional executive modes on procedural justice judgment and outcome acceptance. The study...
The dynamic mechanical properties of Sn-Ag lead-free solders have been studied by means of a split Hopkinson pressure bar (SHPB) at various strain rates. Tests were conducted at room temperature and under uniaxial compressive conditions. It is shown that the Sn-Ag lead-free solders are viscoplastic materials, which are sensitive to the strain rate at higher strain rate. It is found that the materials'...
Accurate estimation of the valve regulated lead-acid (VRLA) batteries ageing, degradation and failure modes are very important for performance maintenance and safe operating conditions. This paper introduces simple but effective techniques that achieve better estimation accuracy. The technique was tested and analyzed by using results obtained from experiments conducted at the YUASA battery laboratories...
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