• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 49
  • 17
  • 16
  • 7
  • 6
  • 4
  • 4
  • 2
  • 2
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 142
  • 25
  • 15
  • 13
  • 11
  • 11
  • 10
  • 9
  • 9
  • 9
  • 8
  • 8
  • 8
  • 7
  • 7
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Study on Electromigration of Flip-Chip Solder Interconnect

Huang, Hsiung-Nien 09 July 2004 (has links)
As the trend of miniaturization of complex integrated circuit(IC) devices, the current density of flip-chip solder bumps have increased significantly and each solder joint is supporting a current density close to or even over 104 A/cm2 .Therefore, in SnPb eutectic solder, which has a high diffusivity at the operating temperature due to its low melting point, the electromigration becomes a major reliability threat. Thus, the thesis is aimed to investigate the effects of electromigration behavior on flip-chip package eutectic Sn-Pb solder bumps reliability under high current density. The current densities are 2x104 A/cm2 and 1.5x104 A/cm2,the surface of die temperatures are 115¢Jand 95¢J.The bump temperature, the histories of the bump resistance, and mean time to failure (MTTF) testings were conducted. The failure mechanism was observed through SEM and EDS. From the results of the experiment, the dominant failure mode of the bump is due to electromigration behavior that causes voids at UBM/bump interface (cathode) when the sample¡¦s failure time is shorter. As the failure time is longer, the failure is also resulted from heat effect in addition to electromigration behavior.
12

Investigations of Heat Seal Parameters and Oxygen Detection in Flexible Packages

Mihindukulasuriya, Suramya Dilrukshi Fernando 25 May 2012 (has links)
Heat sealing is commonly used for making form-fill-seal packages fabricated from thermoplastic films. One of the challenges frequently faced by the industry is inadvertent contamination of the film–film interface by the product during filling, an event that can compromise package seal strength and integrity. In the present study, the effects of dwell time (0.5–1.5 s), jaw pressure (28–1,860 kPa), jaw configuration, jaw temperature (150–180°C), and liquid (water and oil) on the interface temperature and seal strength of a linear low-density polyethylene (LLDPE) film were investigated. In the presence of liquid contaminants, jaw pressure played an important role in displacing the liquid from the seal area allowing the formation of intact seals. Within the experimental conditions investigated, interface temperatures of 130–140°C resulted in optimal seal strength for both water-contaminated and clean film specimens. Thermophysical properties of LLDPE and the contact angle between the contaminant liquid and the polymer films were invoked to explain the seal strength behaviour of the liquid-contaminated LLDPE seals. Further, finite element analysis (FEA) heat transfer models were developed to describe the heat transfer phenomena for LLDPE film during heat sealing, when a liquid contaminant layer is present or absent at the film-film interface. The model predicted the observed temperatures well with root mean square errors (RMSE) ranged from 1.6 to 2.5°C. The FEA approach can potentially be applied to analyze the effect of different contaminant liquids on transient heat transfer during heat sealing. In the second part of this thesis research, an UV-activated oxygen indicator was developed to detect the headspace oxygen within sealed package. The detector involved encapsulating TiO2 nanoparticles, glycerol, and methylene blue within poly(ethylene oxide) fibers using electrospinning. The sensitivity characteristics of the indicator to UV-activation and oxygen detection were investigated. The color recovery rate of the electrospun indicator related negatively to the UV exposure time and to the TiO2 fraction in formulation, possibly due to the ratio of higher free electrons to methylene blue concentration. The indicator can potentially be used as a method to analyze heat seal integrity in modified atmosphere packaging applications. / Natural Sciences and Engineering Research Council (NSERC) of Canada and E.I. Du Pont Canada Co.
13

Some extensions to support vector machines

Masters, A. L. Unknown Date (has links)
No description available.
14

Cognition driven deformation modelling

Janke, A. Unknown Date (has links)
No description available.
15

A support vector machine approach to a classification problem in robotics

Wang, J. Unknown Date (has links)
No description available.
16

Cognition driven deformation modelling

Janke, A. Unknown Date (has links)
No description available.
17

Studie koncepce řízení oběhu obalů ve společnosti Pivovary Lobkowicz, a.s. / The Study of Conception of Packages Management in Lobkowicz Brewery Inc.

Čaládiková, Katarína January 2016 (has links)
The subject of this thesis was to propose an appropriate solution for creating more effective logistics processes which have been connected with the transportation of packages in the company Pivovary Lobkowicz, Inc. Practical experienc and theoretical knowledge obtained from literature was used in conclusions and calculations in the analysis. The flow analysis of packages and information had been created by using selected logistics methods and led to the development of proposal to reduce the number of transportations of empty packages.
18

A nonlinear statistical MESFET model using low order statistics of equivalent circuit model parameter sets

Crampton, Raymond J. 03 March 2009 (has links)
A nonlinear statistical MESFET model is presented which shows good agreement with measured results. A single stage GaAs power amplifier tuned at 13.5 GHz is simulated with the model and accurately predicts output power, input return loss, and power added efficiency. Not only is nominal performance good, but the spreads of amplifier performance seen over many wafers and several lots is represented well. The model consists of capturing low order statistics (means, variances, and correlations) of equivalent circuit model parameter sets and using these to produce a continuous distribution of devices representative of those seen from manufacturing. Complete nonlinear and statistical modeling extraction software packages are also presented which allow easy investigation of many aspects of statistical models such as sensitivity of data set statistics as a function of sample size and how model parameters vary as a function of time with a given fabrication process. / Master of Science
19

Modeling of Flip-Chip and Wire-Bond Chip Scale Packages for RF Chip-Package Co-Simulations

Han, Fu-yi 09 January 2009 (has links)
This dissertation aims to evaluate the package effects on the performance of radio frequency integrated circuits (RFICs) for wireless applications. A model-based study is presented to compare the effects between flip-chip and wire-bond packages on a front-end cascode low-noise amplifier (LNA) in a 2.45 GHz CMOS wireless local area network (WLAN) receiver. To construct the package electrical models, specific modeling dies are designed to help extract the equivalent-circuit elements from measured S-parameters for chip-package interconnects. Furthermore, the ground-proximity effect on on-chip spiral inductors in a flip-chip package is first observed and presented in this modeling study. Excellent agreement between modeling and measurement is obtained by up to 20 GHz for a 64-pin flip-chip ball grid array (FC-BGA) package and a 64-pin wire-bond quad flat nonlead (WB-QFN) package. For practical applications, the established package models are used to predict the degradation of the figure of merit for the cascode LNA under packaged condition. Chip-package co-simulations can achieve good agreement with measurements, and thus can persuasively account for the complete effects caused by the two different packages on the cascode LNA. To simultaneously consider the package and board interconnect effects on RFICs, this dissertation also designs and implements a 1.95 GHz upconverter for the wideband code-division multiple-access (W-CDMA) transmitter. Specific ground wire-bonding and board connection are designed to minimize the linearity degradation due to package and board interconnects. Nonlinear analysis technique is also used to evaluate the nonlinear distortion of the upconverter in the chip-package-board co-design phase. The final measurement results have successfully verified the co-design predictions and simulations for this upconverter.
20

A Study on Post-Weld-Shift and Power Loss in Butterfly Laser Module Packages

Chiu, Hsien-huan 19 July 2004 (has links)
The post-weld-shift (PWS) introduced in the butterfly laser packaging is investigated in this study. The elastic-plastic-thermal coupled finite element model is employed in the stress and deformation analyses. The temperature dependent material properties are used to calculate the residual stresses and the post-weld shift distributions during the packaging process. The finite element package ¡¥MARC¡¦ is used in this study. And the commercial optical software, i.e. ¡¥Zemax¡¦ is also employed in laser power coupling efficiency simulation. The variations of laser welding sequence, Nd-YAG pulse laser power, and initial ferrule¡¦s alignment position on PWS for butterfly laser packaging are studied and discussed in this work. The results indicated adjust the sequence and pulse laser power properly can improve the PWS in butterfly packing significantly. Besides, the PWS correction technique, i.e. the ¡¥Laser Harmering¡¦, is also illustrated in this study. The simulate results showed that proper arrange the welding processes may improve the coupling efficiency over 75¢M.

Page generated in 0.0753 seconds