基于双响应曲面法的稳健参数设计

针对焊膏印刷过程中,设计变量与输出质量特性间非线性关系难以获得的情况,提出了基于双响应曲面法的参数优化方法。以焊膏厚度均值及其方差作为优化目标,首先建立焊膏厚度均值及其方差与设计变量之间的响应曲面模型;其次,考虑焊膏厚度的波动,提出以置信度概念缩小设计区间,以提高设计结果的稳健性。最后,求解最优化模型,其最优解即为最佳参数组合。试验结果表明,采用所提出的方法,工序能力指数Cp从1.01提高到了1.52。     

基于作业成本法下SMT生产线成本的分析及应用

在对作业成本法原理分析的基础上,研究了计算机中使用的集成电路板SMT生产线的成本分配,提出了基于成本动因来划分SMT生产线成本的方法.这种方法为生产管理者提供了比较准确的成本信息,从而为有效控制产品成本,提高产品竞争能力打下基础.     

基于智能对象的SMT车间制造执行系统研究

为了实现电子产品制造过程中对SMT车间的实时、精细化管控,本文提出了一种基于智能对象的SMT车间制造执行系统。通过引入RFID技术与智能对象,给出了基于智能对象的SMT行业制造执行系统框架。在介绍RFID在车间的系统化部署的基础上,详细分析了SMT车间数据采集模式,并描述了贴装过程物料防错流程。最后以广州某电子企业为例,说明了所构建系统的可行性和有效性。     

Total quality control for a surface mount technology process for the manufacture of printed circuit board assemblies

Surface mount technology is used widely nowadays in the manufacture of printed circuit board assemblies in the electronics industry. The occurrence of defective products when this technology is used is mostly caused by technological problems, but sometimes it is also caused by management problems or human errors. When technological problems are being tackled, human interactions will always be involved. This is because the quality of a product is related to the quality of the material, the design of the product and the manufacturing process, and as tasks are subdivided, problems occurring in production cannot be solved completely by the sole effort of a single individual. Hence improvement of product quality involes man, machine, and material. This article explains how quality problems arising from surface mount technology are tackled by team effort in an organization via the implementation of a process-oriented total quality control system.     

Mechanism of improved electromigration reliability using Fe-Ni UBM in wafer level package

Fe-Ni films with compositions of 73 wt% of Ni and 45 wt% of Ni were used as under bump metallization (UBM) in wafer level chip scale package, and their reliability was evaluated through electromigration (EM) test compared with commercial Cu UBM. For Sn3.8Ag0.7Cu(SAC)/Cu solder joints, voids had initiated at Cu cathode after 300 h and typical failures of depletion of Cu cathode and cracks were detected after 1000 h EM. While the SAC/Fe-Ni solder joints kept at a perfect condition without any failures after 1000 h EM. Moreover, the characteristic lifetime calculated by Weibull analysis for Fe-73Ni UBM (2121 h), Fe-45Ni UBM (2340 h) were both over three folds to Cu UBM’s (698 h). The failure modes for Fe-Ni solder joints varied with the different growth behavior of intermetallic compounds (IMCs), which can all be classified as the crack at the cathodic interface between solder and outer IMC layer. The atomic fluxes concerned cathode dissolution and crack initiation were analyzed. When Fe-Ni UBM was added, cathode dissolution was suppressed due to the low diffusivity of IMCs and opposite transferring direction to electron flow of Fe atoms. The smaller EM flux within solder material led a smaller vacancy flux in Fe-Ni solder joints, which can explain the delay of solder voids and cracks as well as the much longer lifetime under EM.     

Component reliability assessment using quantitative and qualitative data

The estimation of a component failure rate depends on the availability of plant specific numerical data. The purpose of this study was development of a new method that explicitly includes numerical and linguistic information into the assessment of a specific failure rate. The basis of the method is the Bayesian updating approach. A prior distribution is selected from a generic database, whereas likelihood is assessed using the principles of fuzzy set theory. The influence of component operating conditions on component failure rate is modeled using a fuzzy inference system. Results of fuzzy reasoning are then used for building an appropriate likelihood function for the Bayesian inference.The method was applied on a high voltage transformer. Results show that with the proposed method, one can estimate the specific failure rate and analyze possible measures to improve component reliability. The method can be used for specific applications including components for which there is not enough numerical data for specific evaluation.     

Comments on the IPC Surface Mount Attachment Reliability Guidelines

The Institute for Interconnecting and Packaging Electronic Circuits (IPC) has published guidelines and standards related to surface mount solder attachments. The latest standard IPC‐9701 was published in 2002. In this paper, the general methodology for creating the aforementioned documents and the related qualification requirements are reviewed and discussed. Also, corrections to the standards and guidelines are proposed. The corrections are related both to the use of formulas and to inaccuracies in the units used. Copyright © 2005 John Wiley & Sons, Ltd.     

Application of Taguchi methods to surface mount processes

This paper describes the implementation of a Taguchi experiment for the placement of surface mount components as part of a process at Mars Electronics. The justification for the experimental work, the practical problems in its implementation and the significance of the results obtained are described. The experiment is seen as part of a programme and the implications of the results obtained for subsequent experimentation are discussed.     

Second‐order reliability method‐based inverse reliability analysis using Hessian update for accurate and efficient reliability‐based design optimization

First‐order reliability method (FORM) has been mostly utilized for solving reliability‐based design optimization (RBDO) problems efficiently. However, second‐order reliability method (SORM) is required in order to estimate a probability of failure accurately in highly nonlinear performance functions. Despite accuracy of SORM, its application to RBDO is quite challenging due to unaffordable numerical burden incurred by a Hessian calculation. For reducing the numerical efforts, a quasi‐Newton approach to approximate the Hessian is introduced in this study instead of calculating the true Hessian. The proposed SORM with the approximated Hessian requires computations only used in FORM, leading to very efficient and accurate reliability analysis. The proposed SORM also utilizes a generalized chi‐squared distribution in order to achieve better accuracy. Furthermore, SORM‐based inverse reliability method is proposed in this study. An accurate reliability index corresponding to a target probability of failure is updated using the proposed SORM. Two approaches in terms of finding an accurate most probable point using the updated reliability index are proposed. The proposed SORM‐based inverse analysis is then extended to RBDO in order to obtain a reliability‐based optimum design satisfying probabilistic constraints more accurately even for a highly nonlinear system. The numerical study results show that the proposed reliability analysis and RBDO achieve efficiency of FORM and accuracy of SORM at the same time. Copyright © 2014 John Wiley & Sons, Ltd.     

Integrated system identification and reliability evaluation of stochastic building structures

System identification and reliability evaluation play a significant role in structural health monitoring to ensure the serviceability and safety of existing structures. Although the development of system identification methods has attained much attention and some degree of maturity, reliability evaluation of existing structures still remains a challenging problem especially when uncertainties in measurement data and inherent randomness, which are inevitably involved in civil structures, are considered. In this regard, this paper presents a framework for integrated system identification and reliability evaluation of stochastic building structures. Two algorithms are proposed to respectively evaluate component reliability and system reliability of stochastic building structures by combining a statistical moment-based system identification method and a probability density evolution equation-based reliability evaluation method. System identification is embedded in the procedure of reliability evaluation of a stochastic building structure. The uncertainties in both the structure and the external excitation are considered. Numerical examples show that the structural component and system reliabilities of a three-story shear building structure with three damage scenarios can be effectively evaluated by the proposed methods.     

包装件振动可靠性的不确定度量化及灵敏度分析

研究包装件参数不确定性对振动可靠性变化的影响,并分析振动可靠性指标对各不确定参数的灵敏度.采用Karhunen-Loeve展开将具有一定谱特征的平稳随机振动表示在标准正态随机变量空间中,应用一阶可靠性方法分析线性包装件振动可靠性指标.考虑缓冲材料弹性特性、阻尼特性、产品主体和脆弱部件之间的弹性特性、阻尼特性四个随机参数...     

飞机内襟翼机构动态响应可靠性分析

基于虚拟样机技术和可靠性分析理论,研究了某飞机内襟翼机构动态响应的可靠性.首先,采用有限元分析软件Patran和动力学分析软件ADAMS建立了刚柔耦合的内襟翼机构虚拟样机,并进行了动态仿真,得到了给定外载荷下襟翼机构保持规定运动规律所需的驱动力随时间变化的规律.其次,分析了滑轨、滚轮尺寸及气动载荷具有随机不确定性且丝杆最大驱动力为定值情况下的襟翼动态卡滞可靠性,通过对运动时域中功能随机过程的极小化变换,用矩方法和随机响应面法对极小化的功能随机函数统计分布规律进行了近似,编程实现了襟翼机构卡滞失效概率的求解,为襟翼运动机构的可靠性设计提供了一种可行方法.     

User control of electronic component reliability in spacecraft applications

This paper elucidates the role of the electronic component engineer in ensuring the reliability of electronic components for high reliability spacecraft applications. The reliability of electronic components is categorized in three areas of responsibility, attributable to the component manufacturer, the user and a shared responsibility between the two. The broad scope of the component engineer's responsibility extends from circuit design to system operation. Co-operation with circuit design engineers for proper part application is emphasized, and the requirements for understanding the effects of environmental stresses on device material properties is treated. The importance of a close working relationship between the component engineer and the part supplier is also emphasized.     

Fatigue life prediction of a rubber mount based on test of material properties and finite element analysis

Failure analysis and fatigue life prediction are very important in the design procedure to assure the safety and reliability of rubber components. The fatigue life of a rubber mount was predicted by combining test of material properties and finite element analysis (FEA). The natural rubber material material’s fatigue life equation was acquired based on uniaxial tensile test and fatigue life tests of the natural rubber. The strain distribution contours and the maximum total principal strains of the rubber mount at different loads in the x and y directions were obtained using finite element analysis method. The critical region cracks prone to arise were obtained and analyzed. Then the maximum total principal strain was used as the fatigue parameter, which was substituted into the natural rubber’s fatigue life equation, to predict the fatigue life of the rubber mount. Finally, fatigue lives of the rubber mount at different loads were measured on a fatigue test rig to validate the accuracy of the fatigue life prediction method. The test results imply that the fatigue lives predicted agree well with the test results.     

非高斯随机振动下包装件时变振动可靠性分析

包装件在流通过程中经常受到非高斯随机振动激励的作用,提出了一种包装件在非高斯随机振动激励条件下的时变可靠性的分析方法。结合多项式混沌扩展和Karhunen-Loeve扩展,提出了基于功率谱(或自相关函数)、均值、方差、偏斜度和峭度信息的非高斯随机振动激励的模拟方法;为减小数值分析量,应用拟蒙特卡洛法,在随机变量空间中合理控制变量的分布模拟非高斯随机振动激励,通过四阶龙格库塔法分析,用较少的随机振动模拟样本准确得到了包装件加速度响应的前四阶矩和自相关函数。基于响应的统计信息,应用该研究提出的多项式混沌扩展、Karhunen-Loeve扩展和拟蒙特卡洛分析,获得包装件加速度响应样本,计算包装件的时变可靠性,用原始蒙特卡洛法验证了计算的准确性;该方法在包装件的可靠性分析、包装系统优化等方面具有重要意义。     

The simulator experimental study on the operator reliability of Qinshan nuclear power plant

The scarcity of human failure data is a major problem that embarrasses human reliability analysts for a long time. In the human reliability analysis of Qinshan nuclear power plant, a full-size simulator was used to conduct an experiment on the operator's reliability. The experiment involves 23 abnormal events and 55 human interactions covering 3 cognitive types: skill-based, rule-based and knowledge-based. The response time and conditions of 38 operators were recorded and the data were analyzed and processed to develop human cognitive reliability model parameters, which match with the features of Qinshan nuclear power plant system and its staff. This paper introduces the background, theory, methods, process, conclusion of the experiment and their comparison with data obtained abroad.     

Collaborative optimization with inverse reliability for multidisciplinary systems uncertainty analysis

This article introduces a method which combines the collaborative optimization framework and the inverse reliability strategy to assess the uncertainty encountered in the multidisciplinary design process. This method conducts the sub-system analysis and optimization concurrently and then improves the process of searching for the most probable point (MPP). It reduces the load of the system-level optimizer significantly. This advantage is specifically more prominent for large-scale engineering system design. Meanwhile, because the disciplinary analyses are treated as the equality constraints in the disciplinary optimization, the computation load can be further reduced. Examples are used to illustrate the accuracy and efficiency of the proposed method.     

Efficient reliability analysis of dynamic k-out-of-n phase-AND mission systems

Motivated by real-world applications of satellites and wireless sensor networks, this paper models and evaluates a dynamic k-out-of-n phase-AND mission system (k/n-PAMS). The mission task conducted by a k/n-PAMS involves multiple consecutive phases; the mission is successful as long as the task is successful in any of the phases. Due to factors, such as scheduled maintenance, location changes in task execution during different phases, and resource sharing with other tasks, the total number of available components n for the considered mission task and the required number of working components k may change from phase to phase. In addition, due to varying load and working environments, component failure time distributions are also phase dependent. This paper proposes an analytical modeling approach based on multivalued decision diagrams (MDDs) for assessing reliability of the considered k/n-PAMS. The approach encompasses a new and fast MDD model generation algorithm that considers behaviors of all the mission phases simultaneously based on node labeling. As demonstrated through empirical studies on k/n-PAMSs with different sizes (different numbers of phases and different numbers of system components), the proposed algorithm is more efficient than the traditional phase-by-phase model generation method.     

基于Kriging模型的充液管道共振非概率可靠性分析

为解决传统概率可靠性在解决流固耦合问题方面的不足,研究了结构不确定参量用超椭球凸集模型和区间变量共同描述下的非概率共振可靠性问题。针对隐式极限状态函数难以求解的问题,引入Kriging模型和超立方抽样技术应用于非概率可靠性分析。该方法用Kriging模型作为近似模型描述原结构,并在计算过程中不断更新近似模型。考虑管道与液体之间的耦合作用,利用有限元软件对所建立的简单管道系统进行模态计算并且结合防共振理论进行充液管路系统的流固耦合振动非概率可靠性分析,用优化的方法计算可靠性指标。工程算例分析表明该方法的合理性,能完善流固耦合管道系统的防共振可靠性分析方法与理论。     

Comprehensive reliability evaluation of multistate complex electromechanical systems based on similarity of cloud models

High reliability and security have become the hallmarks of complex electromechanical systems. Owing to the difficulties in fault data collection, ambiguity and uncertainty have been inevitably associated with complex electromechanical systems. Thus, the ability to perform reliability evaluation using scarce fault data is of immense significance to these machines and is the focus of this study. A similarity based cloud model is proposed to evaluate the running state of complex electromechanical systems. By combining objective and subjective factors, the reliability of complex electromechanical systems is evaluated by calculating the similarity between the cloud models of actual and standardised states. Next, the inverter of an offshore wind turbine is used to verify the accuracy and effectiveness of the proposed approach. The cloud model based framework for reliability evaluation inherits the preponderance of the uncertainty problem, overcomes the drawbacks of the current reliability approaches, and provides a theoretical basis, as well as a practical approach for the maintenance and repair of complex electromechanical systems with missing fault data. Additionally, it also provides a new methodology for solving the uncertainty problems caused by paucity of data.