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Mechanics of Microelectronics
23 Jun 2006-
TL;DR: The state-of-the-art of virtual prototyping is virtual thermo-mechanical prototyping as discussed by the authors, which is the state of the art in the field of prototyping.
Abstract: Microelectronics technology Introduction A heart of silicon In a little black box Baseline CMOS Non-CMOS options Packaging Systems Conclusions References Nomenclature Reliability practices Introduction Reliability assessment Reliability statistics Acceleration factor models Failure mechanisms Conclusions References Exercises Thermal Management Introduction Heat transfer basics Thermal design of assemblies Thermal design for a SQFP Heatsink design choices Conclusions / final remarks References Introduction to Advanced Mechanics Introduction Stress and strain Failure criteria Fracture mechanics Finite element method References Exercises Thermo-Mechanics of Integrated Circuits and Packages Introduction IC Backend and packaging processes and testing Thermo-mechanics of IC backend processes Thermo-Mechanics of packaging processes Thermo-Mechanics of coupled IC backend and packaging processes Case studies References Exercises Characterization and Modeling of Moisture Behavior Introduction Moisture diffusion modeling Characterization of moisture diffusivity and saturation concentration Vapor pressure modeling Hygroscopic swelling characterization & modeling Single void Instability behavior Subjected to vapor pressure and thermal stress Interface strength characterization and modeling Case studies References Exercises Characterization and Modeling of Solder Joint Reliability Introduction Analytical-empirical prognosis of the reliability Thermo-mechanical characteristics of soft solders Data evaluation and LIFE-time estimation Case studies References Exercises Virtual thermo-mechanical prototyping Introduction The state-of-the-art of virtual prototyping Case studies Conclusions References Exercises Challenges and future perspectives Introduction Product and process inputs Tests and experiments Multi-scale mechanics Advanced simulation tools Multi-physics modeling Material and interface behavior Simulation-based optimization Conclusions
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TL;DR: The mathematical descriptions of moisture phase transition with temperature and the governing equations for a deforming polymer with moisture effect are presented in this paper.
143 citations
TL;DR: In this article, the authors examined the commonly-used thermal-moisture analogy approach in thermal-mixture analogy approach and concluded that such an analogy using a normalized concentration approach does not exist in the case of soldering reflow, when the solubility of each diffusing material varies with temperature or the saturated moisture concentration is not a constant over an entire range of reflow temperatures.
Abstract: This paper first examines the commonly-used thermal-moisture analogy approach in thermal-moisture analogy approach. We conclude that such an analogy using a normalized concentration approach does not exist in the case of soldering reflow, when the solubility of each diffusing material varies with temperature or the saturated moisture concentration is not a constant over an entire range of reflow temperatures. The whole field vapor pressure distribution of a flip chip BGA package at reflow is obtained based on a multiscale vapor pressure model. Results reveal that moisture diffusion and vapor pressure have different distributions and are not proportional. The vapor pressure in the package saturates much faster than the moisture diffusion during reflow. This implies that the vapor pressure reaches the saturated pressure level in an early stage of moisture absorption, even the package is far from moisture saturated. However, the interfacial adhesion degrades continuously with moisture absorption. Therefore, the package moisture sensitivity performance will largely reply on the adhesion strength at elevated temperature with moisture. A specially designed experiment with a selection of six different underfills for flip chip packages was conducted. Results confirm that there is no correlation between moisture absorption and the subsequent interface delamination at reflow. The adhesion at high temperature with moisture is the only key modulator that correlates well with test data. Such a parameter is a comprehensive indicator, which includes the effects of thermal mismatch, vapor pressure, temperature and moisture. In this paper, a micromechanics based mechanism analysis on interfacial delamination is also presented. With the implementation of interface properties into the model study, it shows that the critical stress, which results in the unstable void growth and delamination at interface, is significantly reduced when the effect of moisture on debonding is considered.
100 citations
27 May 2008
TL;DR: In this paper, a 3-parameter modified Coffin-Manson approach was proposed to evaluate the solder fatigue of Pb-free (LF) solder for computing and consumer electronics applications.
Abstract: The electronics industry has successfully transitioned from Sn/Pb to Pb free (LF) solder for computing and consumer electronics applications. However, there is no industry-wide standardized LF solder joint reliability model (neither empirical nor FEA-based) available for solder fatigue reliability assessment. A LF solder fatigue model has been proposed in this paper based on a 3-parameter modified Coffin-Manson approach. The proposed model showed best fit to the experimental data (17 pairs of temperature cycle test data) from different sources for multiple package types and sizes including various test conditions. The model fit to the experimental data was excellent and the error was less than 6%. This analysis showed that the LF acceleration factor (AF) model is not significantly different from the Sn/Pb model and proposed model provides best fit to experimental results.
82 citations
TL;DR: In this article, a simplified vapor pressure model based on a multiscale analysis is developed, which considers the phase change in moisture, and links the macroscopic moisture concentration to the moisture state at a microscopic level.
Abstract: Moisture concentration is discontinuous at interfaces when two material, which have different saturated moisture concentrations, are joined together. In order to perform moisture diffusion modeling in a multimaterial system such as electronic packages, normalization methods have been commonly used to remove the discontinuity of moisture concentration at interfaces. However, such treatments cannot be extended to a reflow process, in which ambient temperature and/or humidity vary with time. This paper develops a direct concentration approach, with which the moisture concentration is used as afield variable directly. Constraint equations are applied to meet the interface continuity requirements. Further in this paper a simplified vapor pressure model based on a multiscale analysis is developed. The model considers the phase change in moisture, and links the macroscopic moisture concentration to the moisture state at a microscopic level. This model yields the exact same results with the original vapor pressure model (Fan, et al., 2005, "A Micromechanics Based Vapor Pressure Model in Electronic Packages, " ASME J. Electron. Packag., 127(3), pp. 262-267). The new model does not need to relate to a reference temperature state. Numerical implementation procedures,for calculating moisture concentration and ensuing vapor pressure, which are coupled with temperature analysis, are presented in this paper.
73 citations
12 May 2009-Microsystem Technologies-micro-and Nanosystems-information Storage and Processing Systems
TL;DR: In this article, the authors deal with the thermo-mechanical reliability of microelectronic components and systems and methods to analyse and predict it, the latter promoting the field of nano-reliability for future packaging challenges in advanced electronics system integration.
Abstract: Due to the rapid development of IC technology the traditional packaging concepts are making a transition into more complex system integration techniques in order to enable the constantly increasing demand for more functionality, performance, miniaturisation and lower cost. These new packaging concepts (as e.g. system in package, 3D integration, MEMS-devices) will have to combine smaller structures and layers made of new materials with even higher reliability. As these structures will more and more display nano-features, a coupled experimental and simulative approach has to account for this development to assure design for reliability in the future. A necessary “nano-reliability” approach as a scientific discipline has to encompass research on the properties and failure behaviour of materials and material interfaces under explicit consideration of their micro- and nano-structure and the effects hereby induced. It uses micro- and nano-analytical methods in simulation and experiment to consistently describe failure mechanisms over these length scales for more accurate and physically motivated lifetime prediction models. This paper deals with the thermo-mechanical reliability of microelectronic components and systems and methods to analyse and predict it. Various methods are presented to enable lifetime prediction on system, component and material level, the latter promoting the field of nano-reliability for future packaging challenges in advanced electronics system integration.
65 citations
References
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TL;DR: The algorithm can be used as a building block for solving other distributed graph problems, and can be slightly modified to run on a strongly-connected diagraph for generating the existent Euler trail or to report that no Euler trails exist.
13,828 citations
01 Jan 2006
31 citations
01 Jan 2006
22 citations