Driving Mechanisms of Delamination Related Reliability Problems in Exposed Pad Packages

Exposed pad packages were introduced in the late 1980s and early 1990s because of their excellent thermal and electrical performance. Despite these advantages, the exposed pad packages experience a lot of thermo-hygro-mechanical related reliability problems during qualification and testing. Examples are die lift, which occurs predominantly after moisture sensitivity level conditions, and die-attach to leadframe delamination leading to downbond stitch breaks during temperature cycling. In this chapter, nonlinear finite element (FE) models using fracture mechanics based J-integral calculations are used to assess the reliability problems of the exposed pad package family. Using the parametric FE models any geometrical and material effects can be explored to their impact on the occurrence diepad delamination, and dielift. For instance the impact of diepad size is found to be of much less importance as the impact of die thickness is. Using the fracture mechanics approach, the starting location for the delamination from thermo-hygro-mechanical point of view is deducted. The results indicate that when diepad delamination is present, cracks are likely to grow beneath the die and dielift will occur. The interaction between dielift and other failure modes, such as lifted ball bonds, are not found to be very significant. The FE models are combined with simulation-based optimization methods to deduct design guidelines for optimal reliability of the exposed pad family.     

One-to-Many and Many-to-One Optical Chaos Communications Using Semiconductor Lasers

A theoretical construction of one-to-many (OTM) and many-to-one (MTO) chaos synchronization communications using semiconductor lasers is presented. One center laser provides strong injections (strong link) to other side lasers, and the side lasers also provide weak injections (weak link) to the center one. Simulation results show that the side lasers synchronize with the center laser through injection-locking. In addition, messages transmitted via the strong links or the weak links experience strong chaos pass filtering, enabling us to realize OTM and MTO communications.     

Preparation of CeO2-ZrO2 mixed oxide with high surface area and high thermal stability

Ceria-zirconia solid particles have been recognized as a key material of the automotive exhaust catalysts since they can release and uptake oxygen owing to the rapid reversible oxidation states of cerium between Ce³⁺ and Ce⁴⁺. Several methods have recently been described to prepare the CeO₂-ZrO₂ solid particles used in the catalysts. In this paper, a new coprecipitation method is used to prepare the CeO₂-ZrO₂ solid particles. The Ce-Zr alcogel is dried and calcined in flowing N₂ not in flowing air under atmospheric pressure. The results show that the ceria-zirconia sample calcined at 650 °C has high surface area over 90 m²g⁻¹, which drops to 40 m²g⁻¹ following treatment at 900°C.     

DCOP FOR SMART HOMES: A CASE STUDY

The aim of this article is to bring forth the issue of integrating the services provided by intelligent artifacts in Ambient Intelligence applications. Specifically, we propose a Distributed Constraint Optimization procedure for achieving a functional integration of intelligent artifacts in a smart home. To this end, we employ Adopt-N , a state-of-the-art algorithm for solving Distributed Constraint Optimization Problems (DCOP). This article attempts to state the smart home coordination problem in general terms, and provides the details of a DCOP-based approach by describing a case study taken from the RoboCare project. More specifically, we show how (1) DCOP is a convenient metaphor for casting smart home coordination problems, and (2) the specific features which distinguish Adopt-N from other algorithms for DCOP represent a strong asset in the smart home domain.     

注射成形粘结NdFeB磁体:工艺·性能·应用

综合介绍了几种适于注射成形粘结NdFeB磁体的磁粉制备方法及特点；讨论了粘结剂、改性剂及磁场取向对注射成形NdFeB磁体最终磁性能的影响及其应用市场。在此基础上，指出了今后开展研究工作的方向。     

便携式全站仪在钻采井架钢结构安装中的应用

文章介绍了一种由便携机和全站仪组成的便携式全站仪 ,阐述了该全站仪在钻采井架钢结构施工安装过程中的测量工作 ,对测点产生的误差采用伪逆自由网平差方法进行处理 ,控制点的精度可达到± 5mm ,该全站仪具有快速、灵活、准确的特点 ,不仅提高了生产效率 ,而且达到了对资料的计算机化管理。     

马尔可夫链在企业经济预测上的应用

为了科学的预测企业所关心的各项经济指标 ,以便为企业的未来做出正确的决策方案 ,需用适当的数学模型和方法对企业的经济活动进行定量的研究 .基于经济活动的复杂、多变性及带有许多随机性因素的特点 ,针对这两种常见的经济问题 ,分别建立了相应的马尔可夫链模型 .应用马尔可夫链的相关理论、巧妙的构造转移概率矩阵 ,只通过简单的矩阵运算 ,便迅速解决问题 .实例表明 ,马尔可夫链模型及方法在企业经济活动分析中是可行和适用的 ,可广泛用于解决企业中常见的预测及决策问题 .     

影响道路沥青低温抗裂性能的因素

用弯曲梁流变仪、直接拉伸试验机对7种国内外油源沥青样品进行了低温抗裂性能的评价，从沥青的四组分、相对分子质量及其分布来分析其对沥青低温抗裂性能的影响，结果表明，沥青的相对分子质量分布宽，对沥青的低温抗裂性能有利。     

复杂断块油藏剩余油分布及配套挖潜对策

复杂断块油藏开发后期剩余油分散而难以识别，且其分布受多种因素的控制。在大港油区的港东开发区，根据以纵向1118个时间地层单元为对象的精细油藏描述，提出3类剩余油潜力：①已动用油层，即断层与微构造控制、注采井网不完善、层间非均质性、平面低渗透相带、层内渗流屏障、注采滞留区、边底水锥进等因素形成的剩余油；②新层，即以往未发现的低电阻油层和新发现油砂体；③滚动扩边。在潜力认识的基础上，以单砂体或流动单元为挖潜调整对象，在潜力富集区钻新井、更新井，改变非主力层的驱动方式，重组层系、井网，改变液流方向和间歇注水，并对潜力区配套实施补层、提液、压裂防砂、重复射孔、深度调剖等措施。港东开发区复杂断块油藏实施配套挖潜措施后，提高了高含水期的开发效益与水平。图1参17     

Optimal transfer trees and distinguishing trees for testing observable nondeterministic finite-state machines

The fault-state detection approach for blackbox testing consists of two phases. The first is to bring the system under test (SUT) from its initial state to a targeted state t and the second is to check various specified properties of the SUT at t. This paper investigates the first phase for testing systems specified as observable nondeterministic finite-state machines with probabilistic and weighted transitions. This phase involves two steps. The first step transfers the SUT to some state t' and the second step identifies whether t' is indeed the targeted state t or not. State transfer is achieved by moving the SUT along one of the paths of a transfer tree (TT) and state identification is realized by using diagnosis trees (DT). A theoretical foundation for the existence and characterization of TT and DT with minimum weighted height or minimum average weight is presented. Algorithms for their computation are proposed.