Thermomechanical Response of Materials and Interfaces in Electronic Packaging: Part II—Unified Constitutive Models, Validation, and Design

1997 ◽  
Vol 119 (4) ◽  
pp. 301-309 ◽  
Author(s):  
C. S. Desai ◽  
J. Chia ◽  
T. Kundu ◽  
J. L. Prince
Keyword(s):  
Electronic Packaging ◽  
Constitutive Models ◽  
Cyclic Fatigue ◽  
Failure Model ◽  
Thermomechanical Response ◽  
Disturbed State Concept ◽  
Model Predictions ◽  
Powerful Means ◽  
Models Validation

The constitutive modeling approach based on the disturbed state concept (DSC) described in Part I, provides a unified basis for the characterization of thermomechanical response of materials and joints in electronic chip-substrate systems. Using the material constants given in Part I, the DSC model predictions, obtained by integrating the incremental constitutive equations, are shown here to provide satisfactory backpredietions of stress-strain, fatigue, and failure responses of typical solder materials. The DSC also provides a simple criterion based on the critical disturbance to identify cyclic fatigue failure. Model predictions show good correlation with those from previous models. It is also shown how the DSC model can be used for design applications. Overall, based on Papers I and II, it can be stated that the DSC can provide a new and powerful means to characterize the thermomechanical behavior of materials and joints in a number of problems in electronic packaging.

Thermomechanical Response of Materials and Interfaces in Electronic Packaging: Part I—Unified Constitutive Model and Calibration

1997 ◽  
Vol 119 (4) ◽  
pp. 294-300 ◽  
Author(s):  
C. S. Desai ◽  
J. Chia ◽  
T. Kundu ◽  
J. L. Prince
Keyword(s):  
Laboratory Test ◽  
Constitutive Modeling ◽  
Electronic Packaging ◽  
Cyclic Fatigue ◽  
Failure Behavior ◽  
Thermomechanical Response ◽  
Disturbed State Concept ◽  
Test Behavior ◽  
New Criterion

The disturbed state concept (DSC) presented here provides a unified and versatile methodology for constitutive modeling of thermomechanical response of materials and interfaces/joints in electronic chip-substrate systems. It allows for inclusion of such important features as elastic, plastic and creep strains, microcracking and degradation, strengthening, and fatigue failure. It provides the flexibility to adopt different hierarchical versions in the range of simple (e.g., elastic) to sophisticated (thermoviscoplastic with microcracking and damage), depending on the user’s specific need. This paper presents the basic theory and procedures for finding parameters in the model based on laboratory test data and their values for typical solder materials. Validation of the models with respect to laboratory test behavior and different criteria for the identification of cyclic fatigue and failure, including a new criterion based on the DSC and design applications, are presented in the compendium paper (Part II, Desai et al., 1997). Based on these results, the DSC shows excellent potential for unified characterization of the stress-strain-strength and failure behavior of engineering materials in electronic packaging problems.

Review of Models and the Disturbed State Concept for Thermomechanical Analysis in Electronic Packaging

2000 ◽  
Vol 123 (1) ◽  
pp. 19-33 ◽  
Author(s):  
Chandra S. Desai ◽  
Russell Whitenack
Keyword(s):  
Stress Analysis ◽  
Fatigue Failure ◽  
Constitutive Modeling ◽  
Electronic Packaging ◽  
Cyclic Fatigue ◽  
Thermomechanical Analysis ◽  
Design Analysis ◽  
Thermomechanical Stress ◽  
Disturbed State Concept ◽  
Approximate Procedure

A number of models for thermomechanical stress analysis and fatigue failure of materials are reviewed and their capabilities and limitations are identified. The unified disturbed state concept (DSC) for constitutive modeling of materials and interfaces is presented and compared with other approaches. An approximate procedure based on the DSC is proposed for accelerated design-analysis and cyclic fatigue failure. Solutions of example problems using the DSC and associated computer (FE) procedures are included to illustrate its integrated and improved capabilities for analysis of stresses, strains, microcracking, fracture and fatigue failure, and reliability.

Ball Grid Array Thermomechanical Response During Reflow Assembly

1996 ◽  
Vol 118 (4) ◽  
pp. 214-222 ◽  
Author(s):  
T. E. Voth ◽  
T. L. Bergman
Keyword(s):  
Process Model ◽  
Experimental Studies ◽  
Ball Grid Array ◽  
Mechanical Processing ◽  
Processing Conditions ◽  
System Behavior ◽  
Reflow Soldering ◽  
Thermomechanical Response ◽  
Model Predictions ◽  
Representative System

The thermomechanical response of ball-grid array assemblies during reflow soldering is considered here. Experiments are performed to investigate the thermomechanical response of a representative system and the results are used to validate a numerical model of system behavior. The conclusions drawn from the experimental studies are used to guide development of a process model capable of describing more realistic BGA soldering scenarios. Process model predictions illustrate the system’s thermomechanical response to thermal and mechanical processing conditions, as well as component properties. High thermal conductivity assemblies show the greatest sensitivity to mechanical loading conditions.

Characterization of Hyperelastic (Rubber) Material Using Uniaxial and Biaxial Tension Tests

2012 ◽  
Vol 570 ◽  
pp. 1-7
Author(s):  
Yawar Jamil Adeel ◽  
Ahsan Irshad Muhammad ◽  
Azmat Zeeshan
Keyword(s):  
Shear Test ◽  
Biaxial Tension ◽  
Constitutive Models ◽  
Hyperelastic Material ◽  
Strain Response ◽  
Stress Strain ◽  
Rubber Material ◽  
Tension Tests ◽  
Planar Shear

Hyperelastic material simulation is necessary for proper testing of products functionality in cases where prototype testing is expensive or not possible. Hyperelastic material is nonlinear and more than one stress-strain response of the material is required for its characterization. The study was focused on prediction of hyperelastic behavior of rubber neglecting the viscoelastic and creep effects in rubber. To obtain the stress strain response of rubber, uniaxial and biaxial tension tests were performed. The data obtained from these tests was utilized to find the coefficients of Mooney-Rivlin, Odgen and Arruda Boyce models. Verification of the behavior as predicted by the fitted models was carried out by comparing the experimental data of a planar shear test with its simulation using the same constitutive models.

Bayesian Spectroscopic Characterization of Directly Imaged Planets and Brown Dwarfs and Implications for Ultracool Model Atmospheres

2021 ◽  
Author(s):  
Zhoujian Zhang ◽  
Michael Liu ◽  
Mark Marley ◽  
Michael Line ◽  
William Best
Keyword(s):  
Physical Properties ◽  
Near Infrared ◽  
Brown Dwarfs ◽  
Spectroscopic Characterization ◽  
Cool Temperature ◽  
Brown Dwarf ◽  
Modeling Framework ◽  
High Quality ◽  
Model Predictions

<p>Spectroscopic characterization of imaged exoplanets and brown dwarfs is essential for understanding their atmospheres, formation, and evolution, but such work is challenged by the unavoidably simplified model atmospheres needed to interpret spectra. While most previous work has focused on single or at most a few objects, comparing a large collection of spectra to models can uncover trends in data-model inconsistencies needed to improve model predictions, thereby leading to robust properties from exoplanet and brown dwarf spectra. Therefore, we are conducting a systematic analysis of a valuable but underutilized resource: the numerous high-quality spectra of (directly imaged and free-floating) exoplanets and brown dwarfs already accumulated by the community.<span class="Apple-converted-space"> </span></p> <p>Focusing on the cool-temperature end, we have constructed a Bayesian modeling framework using the new Sonora-Bobcat model atmospheres and have applied it to study near-infrared low-resolution spectra of >50 late-T imaged planets and brown dwarfs (≈600-1200K, ≈10-70 M<sub>Jup</sub>) and infer their physical properties (effective temperature, surface gravity, metallicity, radii, mass). By virtue of having such a large sample of high-quality spectra, our analysis identifies the systematic offsets between observed and model spectra as a function of wavelength and physical properties to pinpoint specific shortcomings in model predictions. We have also found that the spectroscopically inferred metallicities, ages, and masses of our sample all considerably deviate from expectations, suggesting the physical and chemical assumptions made within these models need to be improved to fully interpret data. Our work has established a systematic validation of cloudless model atmospheres to date and we discuss extending such analysis to wider temperature and wavelength (e.g., JWST) ranges, as well as finding new planetary-mass and brown dwarf benchmarks, in order to validate ultracool model atmospheres over larger parameter space.</p>

scholarly journals Quantitative Characterization of a Mitotic Cyclin Threshold Regulating Exit from Mitosis

2005 ◽  
Vol 16 (5) ◽  
pp. 2129-2138 ◽  
Author(s):  
Frederick R. Cross ◽  
Lea Schroeder ◽  
Martin Kruse ◽  
Katherine C. Chen
Keyword(s):  
Cell Cycle ◽  
Budding Yeast ◽  
Cell Cycle Control ◽  
Predictive Ability ◽  
Eukaryotic Cell ◽  
Model Predictions ◽  
Mitotic Cyclin ◽  
Constitutive Overexpression

Regulation of cyclin abundance is central to eukaryotic cell cycle control. Strong overexpression of mitotic cyclins is known to lock the system in mitosis, but the quantitative behavior of the control system as this threshold is approached has only been characterized in the in vitro Xenopus extract system. Here, we quantitate the threshold for mitotic block in budding yeast caused by constitutive overexpression of the mitotic cyclin Clb2. Near this threshold, the system displays marked loss of robustness, in that loss or even heterozygosity for some regulators becomes deleterious or lethal, even though complete loss of these regulators is tolerated at normal cyclin expression levels. Recently, we presented a quantitative kinetic model of the budding yeast cell cycle. Here, we use this model to generate biochemical predictions for Clb2 levels, asynchronous as well as through the cell cycle, as the Clb2 overexpression threshold is approached. The model predictions compare well with biochemical data, even though no data of this type were available during model generation. The loss of robustness of the Clb2 overexpressing system is also predicted by the model. These results provide strong confirmation of the model's predictive ability.

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