Modeling Simplification for Thermal Mechanical Analysis of High Density Chip-to-Substrate Connections

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Ping Nicole An ◽  
Paul A. Kohl
Keyword(s):  
Boundary Conditions ◽  
Flip Chip ◽  
Plane Deformation ◽  
Three Dimensional ◽  
Symmetry Plane ◽  
Mechanical Analysis ◽  
Displacement Error ◽  
Quarter Model ◽  
Thermal Mechanical Analysis ◽  
Time Chip

Finite element modeling (FEM) is an important component in the design of reliable chip-to-substrate connections. However, FEM can quickly become complex as the number of input/output connections increases. Three-dimensional (3D) chip-substrate models are usually simplified where only portions of the chip-substrate structure is considered in order to conserve computer resources and time. Chip symmetry is often used to simplify the models from full-chip structures to quarter or octant models. Recently, an even simpler 3D model, general plane deformation (GPD) slice model, has been used to characterize the properties of the full-chip and local regions on the structures, such as in the structures for solder ball fatigue. In this study, the accuracy of the GPD model is examined by comparing the mechanical behavior of a flip-chip, copper pillar package from various full and partial chip models to that of the GDP model. In addition, it is shown that the GPD model can be further simplified to a half-GPD model by using the symmetry plane in the middle of the slice and choosing the proper boundary conditions. The number of nodes required for each model and the accuracy of the different FEM models are compared. Analysis of the maximum stress in the silicon chip shows that the full-chip model, quarter model, and octant model all convergence to the same result. However, the GPD and half-GPD models, with the previously used boundary conditions, converge to a different stress values from that of the full-chip models. The error in the GPD models for small, 36 I/O package was 4.7% compared to the more complete, full-chip FEM models. The displacement error in the GPD models was more than 50%, compared to the full-chip models, and increased with larger structures. The high displacement error of the GPD models was due to the ordinarily used boundary conditions which neglect the effect from adjacent I/O on the sidewall of the GPD slice. An optimization equation is proposed to account for the spatial variation in the stress on the GPD sidewall. The GPD displacement error was reduced from 50% to 3.3% for the 36 pillar array.

scholarly journals Numerical aspects for efficient welding computational mechanics

2014 ◽  
Vol 18 (suppl.1) ◽  
pp. 139-148
Author(s):  
Tarek Aburuga ◽  
Aleksandar Sedmak ◽  
Zoran Radakovic
Keyword(s):  
Residual Stresses ◽  
Three Dimensional ◽  
Shell Element ◽  
Element Model ◽  
Mechanical Analysis ◽  
Tensile Test Specimen ◽  
Integrity Assessment ◽  
Mass Scaling ◽  
Three Dimensional Models ◽  
Thermal Mechanical Analysis

The effect of the residual stresses and strains is one of the most important parameter in the structure integrity assessment. A finite element model is constructed in order to simulate the multi passes mismatched submerged arc welding SAW which used in the welded tensile test specimen. Sequentially coupled thermal mechanical analysis is done by using ABAQUS software for calculating the residual stresses and distortion due to welding. In this work, three main issues were studied in order to reduce the time consuming during welding simulation which is the major problem in the computational welding mechanics (CWM). The first issue is dimensionality of the problem. Both two- and three-dimensional models are constructed for the same analysis type, shell element for two dimension simulation shows good performance comparing with brick element. The conventional method to calculate residual stress is by using implicit scheme that because of the welding and cooling time is relatively high. In this work, the author shows that it could use the explicit scheme with the mass scaling technique, and time consuming during the analysis will be reduced very efficiently. By using this new technique, it will be possible to simulate relatively large three dimensional structures.

Development of Numerical Model and Coupled Thermal/Mechanical Analysis in the Laser Transmission Joining of PET and Stainless Steel

2011 ◽  
Vol 291-294 ◽  
pp. 1381-1388 ◽  
Author(s):  
Min Feng Jiang ◽  
Xin Hua Song ◽  
Pin Li ◽  
Yang Hu ◽  
Kai Wang ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Temperature Field ◽  
Parametric Design ◽  
Three Dimensional ◽  
Mechanical Analysis ◽  
Stainless Steel Surface ◽  
Residual Stress Field ◽  
Transient Model ◽  
Joint Width ◽  
Thermal Mechanical Analysis

Laser transmission joining of dissimilar and biocompatible materials has potential applications in biomedical implants. In this work, a three-dimensional (3D) transient model for sequentially coupled thermal/mechanical analysis of laser transmission joining of 0.1mm thick PET film and 0.1mm stainless steel has been developed by using the ANSYS parametric design language APLD, along with a moving Gaussian laser heat source. It can be calculated how long it takes to reach the quasi-steady state through the stimulation of the temperature field. The calculated values of the joint width are in good agreement with the experimental results by comparison under conditions of different parameters, which indicates that the model is reliable and is helpful for optimizing process parameters. Then based on the temperature field, the residual stress field distribution on both PET and stainless steel surface is achieved by applying the indirect coupling methods to the analysis. this study also has laid a theoretical foundation for improving the stress distribution on the joint.

Thermal-Mechanical Analysis of Varying Boundary Conditions on a LEU Foil Based Molybdenum-99 Plate Processing Target

2010 ◽  
Author(s):  
Kyler K. Turner ◽  
Gary L. Solbrekken ◽  
Charlie W. Allen
Keyword(s):  
United States ◽  
Boundary Conditions ◽  
Nuclear Reactor ◽  
The United States ◽  
Mechanical Analysis ◽  
Metal Foil ◽  
Enriched Uranium ◽  
Aluminum Plates ◽  
Thermal Mechanical Analysis ◽  
The Impact

Technetium-99m is a diagnostic radio-pharmaceutical that is currently used in 85% of the United States diagnostic imaging procedures [1]. All supplies of technetium-99m’s parent isotope molybdenum-99 currently originate from the irradiation of high enriched uranium (HEU) in nuclear reactor facilities located outside the United States. In accordance with the Global Threat Reduction Initiative all uranium used in future molybdenum-99 production will use low enriched uranium (LEU). Conversion to LEU material effectively mandates using LEU in the form of a metal foil as opposed to current powder based dispersion designs for HEU. Using a foil requires a significant modification to the current target design. One design approach uses an LEU foil sandwiched between two nominally flat aluminum plates. The LEU is enclosed in the sandwiched structure by welding the aluminum plates together about their edges. The plate design is inspired by LEU fuel plates with the exception that the LEU is not bonded to the aluminum plates nor is it necessary to clamp the plate edges to prevent lateral translation. This paper will review the thermal-mechanical analysis of an LEU based molybdenum-99 target with plate geometry. This study describes the impact of boundary conditions on the thermally-induced stress and strain in the aluminum plates.

A Thermal-Mechanical Analysis Model for Composite Overwrapped Pressure Vessel for Hydrogen During Fast Filling

2019 ◽  
Author(s):  
Y. Jiang ◽  
M. Xu ◽  
Zhichao Fan ◽  
Chen Xuedong ◽  
Q. G. Wu
Keyword(s):  
Temperature Distribution ◽  
Pressure Vessel ◽  
Three Dimensional ◽  
Element Model ◽  
Mechanical Analysis ◽  
Cfd Model ◽  
Analysis Model ◽  
Temperature Increment ◽  
Thermal Mechanical Analysis ◽  
Metallic Liner

Abstract Composite overwrapped pressure vessel (COPV) is considered to be the most promising storage tank for hydrogen. Filling the COPV to high pressure within 3–5 minutes generates temperature increment due to negative Joule-Thomson coefficient and compression effect of hydrogen. This temperature increment induces a non-uniform temperature distribution in the COPV. The difference between the physical properties of inner metallic liner and outer composite will produce thermal stress. In this work a computational fluid dynamics (CFD) model is built to simulate the temperature increment during fast filling of the COPV. A three-dimensional thermal-mechanical finite element model for COPV is set up. The temperature distribution of the COPV by the CFD model is input into the thermal-mechanical model to analyze the stress distribution during the fast filling. This thermal-mechanical analysis model will provide technical support for the design of COPV.

scholarly journals Charge algebra in Al(A)dSn spacetimes

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Adrien Fiorucci ◽  
Romain Ruzziconi
Keyword(s):  
Boundary Conditions ◽  
Dirichlet Boundary ◽  
Three Dimensional ◽  
Dirichlet Boundary Conditions ◽  
Boundary Structure ◽  
Asymptotic Symmetry ◽  
Renormalization Procedure ◽  
Field Dependent ◽  
Odd Dimensions

Abstract The gravitational charge algebra of generic asymptotically locally (A)dS spacetimes is derived in n dimensions. The analysis is performed in the Starobinsky/Fefferman-Graham gauge, without assuming any further boundary condition than the minimal falloffs for conformal compactification. In particular, the boundary structure is allowed to fluctuate and plays the role of source yielding some symplectic flux at the boundary. Using the holographic renormalization procedure, the divergences are removed from the symplectic structure, which leads to finite expressions. The charges associated with boundary diffeomorphisms are generically non-vanishing, non-integrable and not conserved, while those associated with boundary Weyl rescalings are non-vanishing only in odd dimensions due to the presence of Weyl anomalies in the dual theory. The charge algebra exhibits a field-dependent 2-cocycle in odd dimensions. When the general framework is restricted to three-dimensional asymptotically AdS spacetimes with Dirichlet boundary conditions, the 2-cocycle reduces to the Brown-Henneaux central extension. The analysis is also specified to leaky boundary conditions in asymptotically locally (A)dS spacetimes that lead to the Λ-BMS asymptotic symmetry group. In the flat limit, the latter contracts into the BMS group in n dimensions.

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