Light emitting diodes reliability review

The increasing demand for light emitting diodes (LEDs) has been driven by a number of application categories, including display backlighting, communications, medical services, signage, and general illumination. The construction of LEDs is somewhat similar to microelectronics, but there are functional requirements, materials, and interfaces in LEDs that make their failure modes and mechanisms unique. This paper presents a comprehensive review for industry and academic research on LED failure mechanisms and reliability to help LED developers and end-product manufacturers focus resources in an effective manner. The focus is on the reliability of LEDs at the die and package levels. The reliability information provided by the LED manufacturers is not at a mature enough stage to be useful to most consumers and end-product manufacturers. This paper provides the groundwork for an understanding of the reliability issues of LEDs across the supply chain. We provide an introduction to LEDs and present the key industries that use LEDs and LED applications. The construction details and fabrication steps of LEDs as they relate to failure mechanisms and reliability are discussed next. We then categorize LED failures into thirteen different groups related to semiconductor, interconnect, and package reliability issues. We then identify the relationships between failure causes and their associated mechanisms, issues in thermal standardization, and critical areas of investigation and development in LED technology and reliability.     

电子设备回收网络决策模型研究

为了便于电子企业在开展电子设备回收业务前定量决策回收网络的规模,在分析现有回收过程特点和决策模型的基础上,提出了四阶段电子设备回收过程模型,并以此为基础,构建了相应的回收网络决策模型.该模型以最低费用为目标构建目标函数,重点考虑物料平衡以及废弃率和翻新率.该模型包含了网络的五项运输费用,七项新建回收中心或外协费用,以及三项政府资助费用,二十二项限制条件.最后通过一个实际算例验证了其有效性.     

New highly conductive organic–inorganic hybrid electrolytes based on star-branched silica based architectures

A new type of organic–inorganic hybrid electrolyte has been developed by a sol–gel process through the reaction of cyanuric chloride with poly(oxyalkylene) diamine and 3-isocyanatepropyltriethoxysilane, followed by co-condensation of 2-[methoxy(polyethyleneoxy)propyl]trimethoxysilane. A maximum ionic conductivity of 1.0 × 10^?4 Scm^?1 at 30 °C has been achieved with the solid hybrid electrolyte. The results of solid-state NMR not only confirm the structural framework of the hybrids, but also provide a microscopic view of the effects of salt concentrations on the dynamic behavior of the polymer chains. The hybrid materials are blended with PVdF-HFP to form the blend hybrid membrane, followed by plasticization with various electrolyte solvents, with the purpose of increasing ionic conductivity. The plasticized blend hybrid electrolyte exhibits a maximum room temperature ionic conductivity of 8.8 × 10^?3 Scm^?1. Such a high ionic conductivity allows it as a potential candidate for applications in lithium ion batteries.