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IEEE International Test Conference

作者： N. Nicolici B.M. Al-Hashimi Computer-Aided Design and Test Group Department of Electrical & Computer Engineering McMaster University Hamilton ONT Canada

Power dissipation during test application is an emerging problem due to yield and reliability concerns. This paper focuses on BIST for RTL data paths and discusses testability trade-offs in terms of test application time, BIST area overhead and power dissipation. Using a complex validation flow and experimental data for over 30,000 testable data paths, it is shown how test application time decreases asymptotically when increasing power constraints. Further, it is experimentally demonstrated why power conscious test synthesis and test scheduling algorithms are required due to large variations in useless power dissipation as test application time decreases. Finally, while previous research has outlined that test application time decreases as BIST area overhead increases, this paper shows that in order to reach high quality solutions in terms of test application time and BIST area overhead under given power constraints, a three dimensional design space needs to be explored.

关键词： Built-in self-test Circuit testing Power dissipation Very large scale integration Application software Logic testing Voltage Power system reliability CMOS technology Electronic equipment testing

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A methodology for fatigue reliability analysis of mechanical components using first order reliability method

A methodology for fatigue reliability analysis of mechanical...

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2001 ASME Pressure Vessels and Piping Conference

作者： Tang, Jun Park, Young Ho Center for Computer-Aided Design College of Engineering University of Iowa Iowa City IA 52242 United States Department of Mechanical Engineering College of Engineering New Mexico State University Las Cruces NM 88003 United States

A new reliability technique that applies cumulative fatigue damage theory and the First Order Reliability Method (FORM) to the random process reliability problem is developed for strain-life analysis-based fatigue reliability assessment Using the proposed method, a family of reliability-defined Ε-Nf curves, referred to as R-Ε-Nf curves, is constructed. An empirical mean stress modified strain-life equation is used as the performance function. The primary focus of this effort has been the implementation of the FORM to define reliability factors used in modifying the conventional Ε-Nf curve to create a family of R-Ε-N f curves, based on the unique reliability factor rule. The proposed method employs the inverse FORM algorithm to achieve computational results, including reliability and the corresponding fatigue life. The method enables the application of fatigue life design for a given cyclic strain history. The method reconciles accuracy and efficiency requirements for random process reliability problems under fatigue failure. A numerical example is presented to demonstrate the proposed method.

关键词： Machine components

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Towards understanding the workspace of the upper extremities

Towards understanding the workspace of the upper extremities

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Digital Human Modeling for design and engineering Conference and Exposition

作者： Abdel-Malek, Karim Yang, Jingzhou Brand, Richard Tanbour, Emad Center for Computer Aided Design Department of Mechanical Engineering University of Iowa Iowa City IA 52242 United States Department of Orthopaedics University of Iowa IA United States Stanley Howe Technical Center Hon Technology Inc. Division of Hon Industries

Significant attention in recent years has been given towards obtaining a better understanding of human joint ranges, measurement, and functionality, especially in conjunction with commands issued by the central nervous system. Studies of those commands often include computer algorithms to describe path trajectories. These are typically in "open-form" with specific descriptions of motions, but not "closed form" mathematical solutions of the full range of possibilities. This paper proposes a rigorous "closed form" kinematic formulation to model human limbs, understand their workspace (also called the reach envelope), and delineate barriers therein where a path becomes difficult or impossible owing to physical constraints. The novel ability to visualize barriers in the workspace emphasizes the power of these closed form equations. Moreover, this formulation takes into account joint limits in terms of ranges of motion and identifies barriers therein where a person is required to attain a different posture. Examples include the workspaces of a typical forearm, a typical finger, and is used to illustrate the visualization of the progress in the functionality of a wrist undergoing rehabilitation. Copyright © 2001 Society of Automotive Engineers, Inc.

关键词： Joints (anatomy)

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Moving Least Square Method for Reliability-Based design Optimization

Moving Least Square Method for Reliability-Based Design Opti...

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The Fourth World Congress of Structural and Multidisciplinary Optimization

作者： K.K.Choi Byeng D.Youn Ren-Jye Yang Center for Computer-Aided Design and Department of Mechanical Engineering The University of Iowa Iowa City IA 52242 Center for Computer-Aided Design and Department of Mechanical Engineering The University of Iowa Iowa City IA 52242 Ford Research Laboratory Dearborn MI 48124

A new reliability-based design optimization (RBDO) method is presented, using a moving lease square (MLS) method and performance measure approach (PMA). This method will provide so-called 6-sigma optimum design. Based on the least square method, the MLS method is introduced to better approximate implicit responses by imposing a variable weight over a compact support. In addition, design sensitivity data is incorporated in the MLS method to demonstrate substantial improvement in accuracy of the approximate sensitivity for RBDO. By taking advantage of the inverse PMA problem, a design of experiment (DOE) framework, that is suitable for reliability analysis, is proposed to properly reproduce the main effects and interactions of design parameters by combining the axial star (AS) and selective interaction (SI) sampling in a single DOE building block. PMA is shown to be much more effective than the reliability index approach (RIA) when response surface methodology (RSM) is used for RBDO. The proposed RSM is integrated with the hybrid mean value (HMV) method of PMA to develop a robust and efficient RBDO process. A large-scale vehicle side impact model example problem is employed to demonstrate the new RBDO method.

关键词： Reliability-Based design Optimization (RBDO), Response Surface Method (RSM), Moving Least Square (MLS), Performance Measure Approach (PMA), Hybrid Mean Value (HMV) Method, and Crash-worthiness.

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Stabilized conforming nodal integration for Galerkin mesh-free methods

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International Journal for Numerical Methods in engineering 2001年第2期50卷 435-466页

作者： Chen, Jiun-Shyan Wu, Cheng-Tang Yoon, Sangpil You, Yang Department of Mechanical Engineering Center for Computer-Aided Design University of Iowa Iowa City IA 52242-1527 United States Department of Mechanical Engineering University of Iowa Iowa City IA 52242-1527 United States

Domain integration by Gauss quadrature in the Galerkin mesh-free methods adds considerable complexity to solution procedures. Direct nodal integration, on the other hand, leads to a numerical instability due to under integration and vanishing derivatives of shape functions at the nodes. A strain smoothing stabilization for nodal integration is proposed to eliminate spatial instability in nodal integration. For convergence, an integration constraint (IC) is introduced as a necessary condition for a linear exactness in the mesh-free Galerkin approximation. The gradient matrix of strain smoothing is shown to satisfy IC using a divergence theorem. No numerical control parameter is involved in the proposed strain smoothing stabilization. The numerical results show that the accuracy and convergent rates in the mesh-free method with a direct nodal integration are improved considerably by the proposed stabilized conforming nodal integration method. It is also demonstrated that the Gauss integration method fails to meet IC in mesh-free discretization. For this reason for proposed method provides even better accuracy than Gauss integration for Galerkin mesh-free method as presented in several numerical examples.

关键词： Galerkin methods

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A Study on Microstructure and Reliability Tests of Low Cost Flip Chip

A Study on Microstructure and Reliability Tests of Low Cost ...

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第四届电子封装国际研讨会

作者： Jian Cai Annette Teng Philip C.H.Chan Simon P.C.Law Guowei Xiao Computer Aided Design & Manufacturing Facility Hong Kong University of Science and Technology Department of Electrical and Electronic Engineering Hong Kong University of Science and Technology

Electroless nickel plating followed by stencil printing is an attractive process because of its cost savings over the conventional high lead C4 *** development of the process for reliability of this low cost bumping process at HKUST is discussed in this *** focus of the study is on the solder and the under bump metallurgy（UBM） microstructure as well as the reliability test results of flip chip on board（FCOB）.Electrical resistance and shear strength were measured to monitor the reliability of the bumped chips under various thermal *** reflows and high temperature aging at 150℃were performed for bumped *** results showed that the shear force would increase with thermal exposure and reach a peak value during the third reflow,subsequent reflows revealed that the shear force would decrease but is still *** and EDS results of the fracture surface indicated that the fracture was cohesive or inside the *** microstructure of solder bump was observed by cross section and SEM to consist of several layers.A layer of NiP at the solder/nickel interface indicated that recrystallization of amorphous Ni-P *** rich layer and Ni-Sn intermetallic compounds（IMC） were *** layer of lead rich solder created a decrease in the strength of the solder ***,bonded FCOB samples with and without underfill were subjected to Condition B temperature cycling *** underfilled units passed 1000 cycles whereas the units without underfill failed after only 110 ***-section showed various modes of cracking on the solder joints including at the UBM.

关键词： IMC UBM A Study on Microstructure and Reliability Tests of Low Cost Flip Chip

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Reliability study and failure analysis of fine pitch solder bumped flip chip on low-cost printed circuit board substrate

Reliability study and failure analysis of fine pitch solder ...

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Electronic Components and Technology Conference (ECTC)

作者： Guo-Wei Xiao P.C.H. Chan A. Teng P.S.W. Lee M.M.F. Yuen Department of Electrical and Electronic Engineering Hong Kong University of Science and Technology Hong Kong China Computer Aided Design & Manufacturing Facility Hong Kong University of Science and Technology Hong Kong China Department of Mechanical Engineering Hong Kong University of Science and Technology Hong Kong China

ISBN: (纸本)0780370384

The design and proper selection of low-cost printed circuit board (PCB) is essential to the reliability and formation of solder joints for the fine-pitch solder-bumped flip-chip on board (FCOB) technology. By nature low-cost PCBs don't have the precision in patterns like the fine-pitch solder-bumped flip-chip technology. In this study, eutectic solder bumps (63Sn/37Pb) were electroplated on the test-chips with various pad pitches and chip sizes. Several types of low-cost PCB designs were evaluated for the fine-pitch solder-bumped flip-chip. The effects of different PCB designs on the formation and shapes of solder joints were studied. The location and formation of voids in the underfill depend on the design and properties of the PCB. The alignment accuracy of the solder mask opening area and the copper pad on the PCB is very critical for the reliability of FCOB technology. The acceptable mis-registration on the low-cost PCB decreases as the chip size increases. Scanning acoustic microscope (SAM), X-ray imaging system, cross-sectioning, scanning electron microscopy (SEM) were used to evaluate and inspect the samples after the thermal cycling test and temperature-humidity test. The solder joint failure modes after thermal tests were studied.

关键词： Failure analysis Flip chip Soldering Electronic packaging thermal management Printed circuits Scanning electron microscopy Acoustic testing System testing Bonding Silicon

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A pressure sensor using flip-chip on low-cost flexible substrate

A pressure sensor using flip-chip on low-cost flexible subst...

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Electronic Components and Technology Conference (ECTC)

作者： Guo-Wei Xiao P.C.H. Chan A. Teng Jian Cai M.M.F. Yuen Department of Electrical and Electronic Engineering Hong Kong University of Science and Technology Hong Kong China Computer Aided Design & Manufacturing Facility Hong Kong University of Science and Technology Hong Kong China Department of Mechanical Engineering Hong Kong University of Science and Technology Hong Kong China

ISBN: (纸本)0780370384

The packaging of microelectromechanical systems (MEMS) is complex and it is essential to the successful commercialization of many MEMS devices. In this paper, a pressure sensor and an actuator were assembled on a flexible substrate using FCOF technology. A photolithography process was developed to meet the solder bump fabrication requirement of the sensor chip. Eutectic solder bumps (63Sn/37Pb) with 250 /spl mu/m pitch were fabricated using the electroplating process. The flexible substrate and flip-chip process were designed for the MEMS package. The electrical test results of the MEMS package satisfied the requirements of devices. The samples were evaluated and inspected using various techniques, such as scanning acoustic microscope (SAM), X-ray imaging, scanning electron microscopy (SEM), etc. The flatness of the flexible substrate was essential to the underfill process and reliability of FCOF technology. Most of the shear failure was located at the interface between the solder mask and flexible substrate after the flip-chip assembly.

关键词： Packaging Micromechanical devices Scanning electron microscopy Assembly Microelectromechanical systems Commercialization Microelectromechanical devices Actuators Lithography Fabrication

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Polymeric nanosphere formed from temperature-responsive polymer composed of (N,N-dimethylamino)ethyl methacrylate and ethyl acrylamide

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Journal of Polymer Science 2001年第5期39卷

作者： Tae Bum Lee Kyoung Tai No Sun Hang Cho Seung Su Kim Jung Ki Seo Jin Ho Lee Soon Hong Yuk Computer Aided Molecular Design Research Center and Department of Chemistry Soong Sil University Seoul 156-743 Korea Advanced Materials Division Korea Research Institute of Chemical Technology P.O. Box 107 Yusung Taejeon 305-600 Korea Department of Polymer Science and Engineering Han Nam University 133 Ojeong Dong Daedeog Ku Taejeon 306-791 Korea

A nanosphere was formed from a temperature-responsive random copolymer of ( N , N -dimethylamino)ethyl methacrylate (DMAEMA) and ethyl acrylamide (EAAm) without a crosslinker. When the copolymerization was performed in a water/ethanol solvent mixture (90/10 v/v %) above the lower critical-solution temperature of poly(DMAEMA- co -EAAm), the nanosphere was formed with the propagation of copolymerization. Atomic force microscopy analysis and dynamic light scattering both showed the formation of nanosphere and the size was decreased as the EAAm content increased in the copolymer. To illuminate this nanosphere formation phenomena, molecular dynamic simulations were performed with model polymer solutions. According to the analysis of the simulation trajectory, the ethyl groups of ethanol bind to the hydrophobic sites of poly(DMAEMA) or poly(DMAEMA- co -EAAm), and water molecules can bind preferentially to CO groups that are abundant on the surface of the core, which is composed of oligomer and ethanol. This may enable the polymerization to proceed within the core, which is transformed into nanosphere. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 594–600, 2001

关键词： polymeric nanosphere temperature-responsive polymer molecular dynamic simulation

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SOFTWARE TOOLS FOR ABSTRACT PROTOTYPING OF design SUPPORT TOOLS

SOFTWARE TOOLS FOR ABSTRACT PROTOTYPING OF DESIGN SUPPORT TO...

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ASME 2000 International design engineering Technical Conferences and computers and Information in engineering Conference, IDETC-CIE 2000

作者： Opiyo, Eliab Z. Horváth, Imre Vergeest, Joris S.M. Delft University of Technology Faculty of Design Engineering and Production Department of Design Engineering Computer Aided Design and Engineering Section Jaffalaan 9 DelftNL-2628 BX Netherlands

ISBN: (纸本)9780791835111

Systematic design, user centered implementation and testing to requirements can contribute significantly to assuring quality of design support tools. The problem is that disorganized requirements elicitation and testing is generally time consuming and can sometimes lead to formulation of incomplete specification requirements. Furthermore, current software testing techniques involve usage of partially or fully implemented prototypes and thus provide feedback for the developers too late. These problems can be avoided through the application of a novel computer based pre-implementation testing technique, called abstract prototyping. It comprises structured multistage design and evaluation cycles, involving both the developers and the potential end-users as the evaluation subjects. This technique introduces quality improvement cycles early in the development process, well before the implementation of prototypes, and provides a structured framework for defining requirements and testing of design support tools. In this paper we first introduce the abstract prototyping technique. Then we describe the architecture and functionality of the software developed for abstract prototyping. We also give an example on the application of this software tool for evaluation of the particle system theory for vague modeling of shapes in conceptual design. This software tool facilitated definition of requirements and testing to the formulated requirements. In this case the particle system theory represented the highest level of abstraction of the vague modeling software tool. The same procedure can be used in the subsequent levels of abstraction of methods, algorithms and pilot implementations. We can argue that the abstract prototyping technique helps to achieve the kinds of improvement and quality gains that are expected in the development of new design support tools and in upgrading the existing tools. Copyright © 2000 by ASME.

关键词： System theory

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