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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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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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Multidisciplinary optimisation with application to exhaust system design

Multidisciplinary optimisation with application to exhaust s...

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8th Symposium on Multidisciplinary Analysis and Optimization 2000

作者： Nyström, Mattias Department of Mechanical Engineering Division of Computer Aided Design Lulea University of Technology SE-971 87 Luleå Sweden

The design process in automotive industry involves several different analysis disciplines. This study focuses on applying multidisciplinary optimisation to the design of exhaust systems using commercial software. The software that has been used are a solid modelling Mechanical computer aided Engineereing system, a Finite Element Method solver, a computational Fluid Dynamics solver and optimisation software. An environment for exhaust system design supported by multidisciplinary optimisation has beendeveloped. The objective is to present the environments infrastructure and a method to optimise the aeroacoustic as well as the structural dynamic characteristics of the system. © 2000 The American Institute of Aeronautics and Astronautics Inc. All rights reserved.

关键词： Structural dynamics

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METHOD AND CODE FOR THE VISUALIZATION OF MULTIVARIATE SOLIDS

METHOD AND CODE FOR THE VISUALIZATION OF MULTIVARIATE SOLIDS

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

作者： Abdel-Malek, Karim Yang, Jingzhou Department of Mechanical Engineering Center for Computer Aided Design The University of Iowa Iowa CityIA52246 United States

ISBN: (纸本)9780791835128

This paper is devoted to a method and computer code for the automatic visualization of multivariate solids. Example of a multivariate solids arise in computer aided geometric design when a geometric entity is swept in space, where the totality of points touched by the entity is called the swept volume and is characterized by an equation of many parameters. The method and code are presented in an integrated manner and are aimed at providing the reader with a replicable computer algorithm. The formulation for is based on the implicit function theorem;is applicable to the visualization of solids of any number of parameters;and produces the exact boundary representation. Considering the solid as a manifold (possibly with boundaries), it is shown that further stratification of the various submanifolds yields varieties that can be depicted in R 3. A measure of the computational complexity is presented to give the reader a sense of robustness of the method. The code is developed using a symbolic manipulator and is presented with a number of examples. © 2000 by ASME.

关键词： Visualization

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ON THE PLACEMENT OF SERIAL MANIPULATORS

ON THE PLACEMENT OF SERIAL MANIPULATORS

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

作者： Abdel-Malek, Karim Yu, Wei Department of Mechanical Engineering Center for Computer Aided Design University of Iowa Iowa CityIA52246 United States

ISBN: (纸本)9780791835173

Criteria and implementation for the placement robot manipulators with the objective to reach specified target points are herein addressed. Placement of a serial manipulator in a working environment is characterized by defining the position and orientation of the manipulator's base with respect to a fixed reference frame. The problem has become of importance in both the medical and manufacturing fields, where a robot arm must be appropriately placed with respect to targets that cannot be moved. A broadly applicable numerical formulation is presented. While other methods have used inverse kinematics solutions in their formulation for defining a locality for the manipulator base, this type of solution is difficult to implement because of the inherent complexities in determining al inverse kinematic solutions. The approach taken in this work is based on characterizing the placement forcing a cost function to impel the workspace envelope in terms of surface patches towards the target points and subject to functionality constraints, but that does not require the computation of inverse kinematics. The formulation and experimental code are demonstrated using a number of examples. Copyright © 2000 by ASME.

关键词： Inverse kinematics

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design sensitivity analysis and optimization of nonlinear transient dynamics

Design sensitivity analysis and optimization of nonlinear tr...

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8th Symposium on Multidisciplinary Analysis and Optimization 2000

作者： Ki, Nam H. Choi, Kyung K. The Center for Computer-Aided Design and Department of Mechanical Engineering College of Engineering The University of Iowa Iowa City IA 52242 United States

A shape design sensitivity analysis and optimization of structural transient dynamics are proposed for the finite deformation elastoplastic materials under impact with a rigid surface. A shape variation of the structure is considered using the material derivative approach in continuum mechanics. A penalty method, modified Coulomb friction law, and the slave-master concept are used for the impact problem. Hyperelasticity-based multiplicatively decomposed elastoplasticity is used for the constitutive model. The implicit Newmark time integration scheme is used for the structural dynamics. The design sensitivity equation is solved at each converged time step with the same tangent stiffness matrix as response analysis without iteration. The cost of sensitivity computation is more efficient than the cost of response analysis for the implicit time integration method. The efficiency and the accuracy of the proposed method are shown through the design optimization of a vehicle bumper. © 2000 by Nam H. Kirn and Kyung K. Choi.

关键词： Elastoplasticity

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design POTENTIAL CONCEPT FOR RELIABILITY-BASED design OPTIMIZATION

DESIGN POTENTIAL CONCEPT FOR RELIABILITY-BASED DESIGN OPTIMI...

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

作者： Choi, Kyung K. Tu, Jian Park, Young H. Center for Computer-Aided Design Department of Mechanical Engineering College of Engineering The University of Iowa Iowa CityIA52242-1000 United States

ISBN: (纸本)9780791835128

This paper presents a design potential concept for reliability-based design optimization by integrating the probability analysis into the design optimization process. The reliability-based system parameter design is illustrated by the design potential concept in a unified system space, where design potential surfaces are derived from first-order reliability methods and an adaptive strategy is developed for robust and more efficient probabilistic constraint evaluation. More important, the design potential concept provides an in-depth understanding of reliability-based design optimization and leads to a design potential method that can significantly accelerate the process of robust system parameter design optimization. © 2000 by ASME.

关键词： Reliability analysis

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design optimization of deepdrawing process

Design optimization of deepdrawing process

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8th Symposium on Multidisciplinary Analysis and Optimization 2000

作者： Choi, Kyung K. Kim, Nam H. The Center for Computer-Aided Design Department of Mechanical Engineering College of Engineering The University of Iowa Iowa City IA52242 United States

The design optimization of deepdrawing process in manufacturing is proposed to control the final shape of the workpiece after elastic springback. The manufacturing process design problem is formulated to minimize the difference between the shape of the desired •workpiece geometry and the final analysis result after elastic springback. Nonlinear structural problem that includes elastoplasticity withfrictional contact is solved using a meshfree method where the structural domain is discretized by a set of particle points. Continuumbased design sensitivity analysis (DSA) is carried out to efficiently obtain the gradient information for the optimization. The shape of the workpiece and the geometry of the rigid die are treated as design variables. The accuracy of the sensitivity result is compared with the finite difference result with excellent agreement. The optimum stamping process improves the quality of the final product significantly. © 2000 by Kyung K. Choi and Nam H. Kim.

关键词： Sensitivity analysis

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Nonlinear version of stabilized conforming nodal integration for galerkin meshfree methods

Nonlinear version of stabilized conforming nodal integration...

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European Congress on computational Methods in Applied Sciences and engineering, ECCOMAS 2000

作者： Chen, Jiun-Shyan Wu, Cheng-Tang Yoon, Sangpil Department of Mechanical Engineering Center for Computer-Aided Design University of Iowa 2137 Seamans Center Iowa City IA 52242 United States

ISBN: (纸本)8489925704

A Stabilized Conforming (SC) nodal integration, which meets the integration constraint in the Galerkin meshfree approximation, is generalized for nonlinear problems. In SC nodal integration, a strain smoothing stabilization is introduced and applied to the deformation gradient using a Lagrangian meshfree discretization. The assumed strain method expressed in terms of deformation gradient is employed to formulate an efficient meshfree discrete equation for nonlinear problems. A significant gain in computational efficiency is achieved, as well as enhanced accuracy, in comparison to the solution of meshfree method using Gauss integration method. The performance of the proposed method appears to be quite robust when dealing with irregular discretization.

关键词： computational efficiency

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