Filler-induced failure mechanism in plastic-encapsulated microelectronic packages

Based on empirical data, the present work provides a model to prevent filler-induced reliability degradation in plastic-encapsulated LOC (lead-on-chip) packages. According to the model, the maximum size of the silica fillers included in the plastic package body should be smaller than one half of the inter-distance between the device and its overlying lead-frame. In particular, it is shown in the model that the spherical silica particles, which are sometimes trapped in the space between the top surface of the device and the bottom of the lead-frame during the encapsulating process, can induce huge compressive stress on a specific site of the integrated circuit pattern due to the thermal shrinkage of the plastic package body. Further, the present model suggests that tiny fillers squeezed beneath a large trapping filler might directly attack the brittle layer of the device pattern because the compressive force from the large filler particle can develop into huge compressive stress due to the reduced load-carrying area.     

三体磨料塑变磨损中磨粒运动方式的研究

对三体磨料磨损中磨粒的运动方式做了进一步的理论分析，基于三体磨料磨损中塑变疲劳磨损起主要作用，为突出塑变疲劳磨损的作用，选择圆形磨料进行研究，分析了圆整磨料在三体磨料磨损界面中滚动、滑动的判定，提出了相对滑动界面的判定。     

Microstructural change of ultrafine-grained aluminum during high-speed plastic deformation

Effect of strain rate on microstructural change in deformation of the ultrafine grained (UFG) aluminum produced by severe plastic deformation (SPD) was studied. Commercial purity 1100 aluminum sheets were highly strained up to an equivalent strain of 4.8 by the Accumulative Roll-Bonding (ARB) process at ambient temperature. The ARB-processed sheets were found to be filled with pancake-shaped ultrafine grains surrounded by high-angle grain boundaries. The ultrafine grains had a mean grain thickness of 200 nm and a mean grain length of 1100 nm. The ultrafine-grained aluminum sheets were deformed at various strain rates ranging from 2 to 6.0×10⁴ s⁻¹ by conventional rolling, ultra-high-speed rolling, and impact compression. High-speed plastic deformation generates a large amount of heat, inducing coarsening of the ultrafine grains during and after deformation. On the other hand, it was also suggested that high-speed plastic deformation is effective for grain-subdivision, in other words, ultra-grain refinement, if the effect of heat generation is extracted.     

深井塑性水泥浆体系研究

在深井的固井过程中经帮会面临大段盐膏层固井问题。深井本身具有井深、温度高、水泥环薄的特点，再加上地层盐水的侵入而使水泥浆性能发生变化，加大了固井难度；而且一般水泥石本身具有硬和脆的性质，易受后续施工、射孔或地下复杂作用力的影响而发生脆裂，或与套管、井壁剥离。采用以改性纤维为主要材料的早强增塑剂QA研究出了深井抗盐塑性水泥浆体系。对塑性水泥浆的惜规性能和抗盐、抗温能力及密度可调性进行了试验分析研究。试验结果表明，加入QA的水泥浆的惜规性能指标与不加QA的水泥浆接近，但水泥石抗裂程度明显提高，抗压强度增加25％～30％，7d的抗冲击韧性提高16．6％～22．3％，抗折强度提高18％～21％，弹性模量降低约17％；而且水泥浆抗盐性能优良，使用温度和密度范围宽，与各类外加剂配伍性好，流变性好，直角稠化，强度发展快，粘接强度高，有利于复杂地层的固井施工；工艺简单，操作方便，适宜现场推广运用。     

Finite element simulation of the mechanics of flat contact pad fretting fatigue tests

An understanding into the macro kinetic and kinematic behaviour of fretted surfaces is provided. Making use of a modified version of a previously developed in‐house two‐dimensional elastic–plastic finite element analysis numerically simulates flat contact pad fretting fatigue tests. Basic macro mechanics concepts are adopted to idealise two bodies with rough contact surfaces and loaded at two different sites with arbitrary axial loading profiles. A time scale factor is devised to recognise the earliest candidate out of the events possibly accommodated at each loading increment. The present analysis utilises a relevant experimental set up developed in the Structural Integrity Research Institute of the University of Sheffield as an application. Computational results accurate to within 1.2% and corresponding to one contact pad span and six constant normal loads acting individually with four amplitudes of two sinusoidal axial load cycles are presented. The present computations include (1) the development of the global and local normal and tangential reactions and relative sliding displacement acting along the fretting surfaces and (2) contact pad deformation, generated stress fields and plasticity development within the neighbouring region of the fretted area.     

土工格室在生态防洪工程中的应用

河北省迁安市滦河生态防洪工程是河北省重点工程建设项目，在建设中采用土工格室生态护岸工程技术，不仅大大提高了工程建设的速度和质量，而且延长了堤坝使用寿命，减少了维护成本，收到了环保、生态等方面的综合效益。     

高炉喷吹废塑料燃烧动力学研究

为了提供高炉喷吹废塑料新技术工业化应用的理论依据，通过对其动力学参数的求解，研究了高炉喷吹废塑料的燃烧动力学，得出了该燃烧反应是一级反应，且在温度为200℃、塑料配比为20％～25％时活化能最低、燃烧阻力小的结论。     

超细分子筛材料的合成与应用研究进展

综述了近几年超细分子筛的合成与应用方面的研究进展,重点介绍了几种常用且研究较多的分子筛,主要包括Y,ZSM-5,β,Silicalite-1,ZSM-35,MCM-22等分子筛。对超细分子筛的合成方法及其在石化、环保和生物等领域的应用进行了介绍,并对分子筛复合材料的研究及应用的最新动态进行了评述,说明超细分子筛材料的应用领域仍在不断拓宽,超细分子筛复合材料的研究将会成为分子筛材料领域未来的重要发展方向。     

微光机电系统的微绞链研制

本文讨论了非硅微机械工艺和微绞链的研制工艺。我们研制的非硅表面微机械工艺采用两次或三次掩模电镀层，聚酰亚胺和光刻胶分别作为底层和第二、第三层的牺牲层。用这套工艺，研制成功了三种不同种类的微绞链。微绞链能在基片表面作０—１８０度自由转动。     

Flexible microelectronics becoming a reality with Suftla transfer technology

Abstract— Suftla is a technology that is used to transfer polycrystalline silicon (polysilicon) thin‐film‐transistor (TFT) circuits from an original glass substrate to a plastic sheet. The electronic devices in the next generation will be thin, lightweight, and will handle huge amounts of data, yet consume less energy. Suftla technology, together with high‐performance polysilicon TFTs, meets all these requirements because we have developed a variety of smart flexible electronic devices, such as thin paperback‐sized displays and microprocessors. Suftla will usher in a new era of life‐enhancing flexible microelectronics.