Failure mechanism models for electromigration

This tutorial illustrates situations where electromigration (a wearout failure mechanism) in electronic devices can degrade performance. Electromigration and its relation to microstructure is discussed. Temperature considerations are treated. A practical model for electromigration and two application examples of it are given. Qualitative design procedures for avoiding solid-state electromigration failure are briefly discussed     

Failure mechanism models for brittle fracture

This tutorial illustrates designs where brittle fracture can endanger system performance, thereby acting as an overstress failure mechanism. Analytic (physics-of-failure) methods, based on continuum fracture-mechanisms rather than on molecular micro-mechanics, are presented to design against such failures. The associated stress-analysis techniques and material characterizations have matured appreciably over the past 40 years and are routinely used in aerospace, automotive, and other mechanical/structural applications. Two examples illustrate the use of these models in practical electronic packaging     

Failure mechanism models for ductile fracture

This tutorial illustrates design situations where ductile fracture of some components can compromise system performance, thereby acting as an overstress failure mechanism. Analytic (physics-of-failure) methods, based on continuum fracture mechanics principles, are presented to design against such failures. Examples illustrate the use of these models in practical design situations in mechanical engineering and electronic packaging. The design equations are based on continuum mechanics rather than on molecular micromechanics, and can be implemented in an engineering design environment. The associated stress analysis of ten requires numerical finite-element techniques. The methods for material-property characterizations have matured appreciably over the past 40 years and are specified in engineering handbooks     

Failure mechanism models for cyclic fatigue

This work illustrates design situations where mechanical fatigue under cyclic loading, of one or more components, can compromise system performance. In this failure mechanism, damage accumulates with each load cycle, thereby causing a physical wearout failure mechanism. Phenomenological continuum length-scale models, based on micromechanical considerations, are presented to predict the onset (or initiation) of fatigue cracking in ductile materials. Fatigue crack propagation is modeled with continuum fracture mechanics principles. The number of load cycles required to cause failure is predicted based on these models. Approaches for modeling creep fatigue interactions are briefly discussed. Analytic physics-of-failure method and examples are presented for designing against wearout failure due to cyclic fatigue. These models can be implemented in an engineering design environment. The associated stress analysis requires numerical finite element techniques in many cases. The associated material property characterization techniques have matured since the 1950s and are specified in engineering handbooks     

Failure mechanism models for material aging due to interdiffusion

This tutorial illustrates design situations where material aging due to interdiffusion in some components can compromise system performance over time, thereby acting as a wearout failure mechanism. Microstructural diffusion mechanisms, continuum diffusion models, and interdiffusion analysis techniques are presented to design against such failures. An example illustrates the application of the mechanisms, models, and techniques in electronic packaging     

电铸超细晶Cu超高速变形机理的TEM研究

电铸材料由于具有独特的显微组织结构和晶粒生长方向的可控性而广泛地应用于工业及军事等领域。本文应用电铸法制备超细晶粒金属Ｃｕ ,对电铸工艺参数与形成的材料的微观组织的关系进行了探讨。运用扫描电子显微镜 (ＳＥＭ )、透射电子显微镜(ＴＥＭ)和ＥＰＳＤ等实验手段 ,对电铸Ｃｕ的显微组织及晶粒的生长方向进行了系统的研究 ,对超高速塑性变形机理进行了初步探讨。实验方法电铸法加工是在芯模上电沉积一定厚度的连续金属后再与之分离得到金属薄壳零件的成形技术 ,它是利用电解原理的相反过程来进行的[1] 。本研究采用不锈钢芯模作为阴…     

Failure-mechanism models for excessive elastic deformation

Design situations where excessive elastic deformations can compromise system performance, thereby acting as a failure mechanism, are illustrated. Models, based on continuum mechanics, to design against such failures are presented. Two examples illustrate the use of these models in practical design situations in electronic packaging and in mechanical systems. The examples use deterministic models, for simplicity of presentation. In reality, each of the variables in the design equation is uncertain, e.g. geometric dimensions, material properties, and applied loads. If these uncertainties are important then they must be accounted for by the usual statistical methods     

Detection of plastic deformation in metals with photoacoustic microscope

The detection of plastic deformation of polycrystalline metal samples like brass and aluminium using a photoacoustic microscope is reported. The method can also be used to monitor the effect of heat treatment and perhaps even to reveal the stamped images on archaeological coins.     

纯镁动态塑性变形的微观组织演变

采用高应变速率对纯镁热压板材进行动态塑性变形(DPD)。利用光学显微镜、X射线衍射仪和场发射电子枪扫描电镜的EBSD系统等分析DPD变形前后的微观组织和织构演变过程。结果表明,动态塑性变形使纯镁中原始大晶粒发生破碎,形成细小不规则新晶粒,产生细化作用,大晶粒晶界处由于高位错密度形成了亚晶界;通过EBSD在二次孪晶内部观察到了与基体成20°～30°取向差的再结晶晶粒;DPD形变5%的孪生率是8.27%,形变8%时孪生率增加到9.88%。     

纯镁动态塑性变形的微观组织演变

采用高应变速率对纯镁热压板材进行动态塑性变形(DPD).利用光学显微镜、X射线衍射仪和场发射电子枪扫描电镜的EBSD系统等分析DPD变形前后的微观组织和织构演变过程.结果表明,动态塑性变形使纯镁中原始大晶粒发生破碎,形成细小不规则新晶粒,产生细化作用,大晶粒晶界处由于高位错密度形成了亚晶界;通过EBSD在二次孪晶内部观...     

氦－镉激光器的失效机制

本文报道国产氦-镉激光器常出现的导致失效的一些现象,并阐明其机制.同时给出一些改进意见及修理方法.     

氦－镉激光器的失效机制

本文报道国产氦－镉激光器常出现的导致失效的一些现象，并阐明其机制。同时给出一些改进意见及修理方法。     

Photoluminescence properties of GaN with dislocations induced by plastic deformation

Fresh (a/3)[1120] dislocations on the (1100) prismatic plane were introduced into GaN bulk crystals by plastic deformation at 950–1000°C. In photoluminescence studies at 11 K, the near-band-edge (3.48 eV) luminescence intensity decreased remarkably in the deformed GaN, which was attributed to the introduction of high-density nonradiative recombination centers during plastic deformation. The yellow-band luminescence (2.22 eV) decreased due to plastic deformation, while several luminescence bands centered at 1.79, 1.92, and 2.4 eV developed. The dependence of PL features on deformation and annealing suggests that yellow luminescence is not related to the native structure of edge dislocations in GaN.     

Failure analysis of leakage current in plastic encapsulated packages

Plastic encapsulated packages exhibit high leakage currents after a few hundred hours in the steam pressure pot test (SPP). The present study investigates two possible causes of leakage current. These are: (a) mold compound, (b) the polyimide tape used for co-planarity of lead frame fingers. The results of this study indicate that the leakage cur-rent is independent of the frame and is not caused by the mold compound. The data indicates that it is the ionic content and acrylic-based adhesive layer of the polyimide tape which cause the leakage current. To eliminate the leakage current, polyimide tape with low ionic content and non acrylic-based adhesive should be used. *Permanent address: School of Physics, Universiti Sains Ma-laysia, 11800 USM Penang, Malaysia.     

超高纯铝在动态塑性变形过程中的微观组织演化

利用金相显微镜和EBSD技术对超高纯铝(99.999％)在动态塑性变形(dynamic plastic deformation,DPD)过程中的微观组织及取向差进行了表征,分析了超高纯铝在DPD变形方式下组织的演变规律.     

Failure correlation in software reliability models

Perhaps the most stringent restriction in most software reliability models is the assumption of statistical independence among successive software failures. The authors research was motivated by the fact that although there are practical situations in which this assumption could be easily violated, much of the published literature on software reliability modeling does not seriously address this issue. The research work in this paper is devoted to developing the software reliability modeling framework that can consider the phenomena of failure correlation and to study its effects on the software reliability measures. The important property of the developed Markov renewal modeling approach is its flexibility. It allows construction of the software reliability model in both discrete time and continuous time, and (depending on the goals) to base the analysis either on Markov chain theory or on renewal process theory. Thus, their modeling approach is an important step toward more consistent and realistic modeling of software reliability. It can be related to existing software reliability growth models. Many input-domain and time-domain models can be derived as special cases under the assumption of failure s-independence. This paper aims at showing that the classical software reliability theory can be extended to consider a sequence of possibly s-dependent software runs, viz, failure correlation. It does not deal with inference nor with predictions, per se. For the model to be fully specified and applied to estimations and predictions in real software development projects, we need to address many research issues, e.g., the detailed assumptions about the nature of the overall reliability growth, way modeling-parameters change as a result of the fault-removal attempts     

Overview of fatigue performance of Cu processed by severe plastic deformation

This study investigates discrepancies regarding cyclic softening of Cu processed by severe plastic deformation (SPD). All samples softened if the microhardnesses before and after fatiguing are compared. However, the effect decreases if the strain amplitude is small, Δε_p <1 × 10⁻³). Samples with equiaxed subgrains were more resistant to softening and thermal recovery. All samples had “persistent” shear bands except those tested at the highest amplitudes, Δε_p >1 × 10⁻². Cu processed by SPD exhibits an enhanced fatigue life at low amplitudes. However, low thermal stability, potential for softening, and poor low-cycle properties discredit this advantage.     

对电子元器件的失效机理分析

本文对电子元器件失效机理进行分析和探讨,旨在为元器件以及设备的检修提供理论支持.