Evaluation of Low Order Stress Models for Use in Co-Design Analysis of Electronics Packaging

2019 ◽  
Author(s):  
L. M. Boteler ◽  
S. M. Miner
Keyword(s):  
Thermal Stresses ◽  
Design Space ◽  
Coefficient Of Thermal Expansion ◽  
Electronics Packaging ◽  
Analysis Tool ◽  
Module Design ◽  
Induced Stresses ◽  
Plane Distribution ◽  
Stress Models ◽  
Low Order

Abstract Co-design and co-engineering have the potential to improve the design of electronics packaging significantly. A co-designed approach moves away from the sequential approach of an electrical layout followed by a mechanical module design, and then the addition of a heat sink. Replacing it with an approach that addresses the electrical, thermal, and mechanical design simultaneously during the initial design. The goal is to evaluate the design space quickly, considering both the thermal and mechanical stress aspects together. ParaPower is a low order fast running parametric analysis tool, developed by the Army Research Laboratory (ARL), that allows rapid evaluation of package temperatures and coefficient of thermal expansion (CTE) induced stresses throughout the design space. The model uses a 3D nodal network to calculate device temperatures and thermal stresses. In order to rapidly evaluate the design space both the thermal and stress models must be reduced order and provide reasonable results on coarse grids. In the case of the stress model, the goal is a low order relationship between the temperatures and the CTE induced stresses. This paper compares three different low order models for stress. The first uses a more traditional planar module design. This assumes a substantial substrate or heat spreader as the base for the module assembly. The second model is less restrictive, eliminating the requirement for a substrate. The third model also eliminates the substrate requirement, but also allows for in-plane distribution of the stresses. The first two models do not account for the in-plane distribution. Two geometries are considered, a standard power module with a substantial substrate and a stacked novel module with no clear substrate layer. Results for both geometries and the three stress models are compared to finite element analysis (FEA) using SolidWorks, beginning with a thermal analysis followed by a stress analysis based on the temperature solution. All three models run roughly two orders of magnitude faster than the FEA and they correctly predict the trends in the CTE induced stresses.

Comparison of Thermal and Stress Analysis Results for a High Voltage Module Using FEA and a Quick Parametric Analysis Tool

2018 ◽  
Author(s):  
L. M. Boteler ◽  
S. M. Miner
Keyword(s):  
Stress Analysis ◽  
High Voltage ◽  
Parametric Analysis ◽  
Thermal Stresses ◽  
Analysis Tool ◽  
Element Analysis ◽  
Module Design ◽  
Fast Running ◽  
Packaging Structure ◽  
Low Order

A low order fast running parametric analysis tool, ParaPower, was used to arrive at the design for a novel high voltage module. The low order model used a 3D nodal network to calculate device temperatures and thermal stresses. The model assumed heat flux generated near the top surface of each device which is then conducted through the packaging structure and removed by convection. The temperature distribution is used to calculate thermal stresses throughout the package. This co-design modeling tool, developed for rectilinear geometries, allowed a rapid evaluation of the package temperatures and CTE induced stresses throughout the design space. However, once the final design configuration was determined a detailed finite element analysis was performed to validate the design. This paper compares the results obtained using ParaPower to the FEA, demonstrating the usefulness of the parametric analysis tool. Results for both temperature and CTE induced stress are compared. Two different stress models are evaluated. One based on the more traditional planar module design, which assumes a substantial substrate or heat spreader on which the module is assembled. The other model is less restrictive, eliminating the requirement for a substrate. The FEA modeling was performed using SolidWorks beginning with a thermal analysis followed by a stress analysis based on the temperature solution. Both the values and the trends of the temperatures and stresses were evaluated. The temperature results agreed to within 3.2°C. The trends and sign of the stresses were correctly predicted, but the magnitudes were not. One of the significant advantages of ParaPower is the speed of the computation. The run time for the parametric analysis was roughly two orders of magnitude faster than the FEA. This made it possible to build the model and complete the parametric analysis of roughly 500 runs in less than a day.

Deformation at interfaces of Ti-6Al-4V/SiC fiber composites

1992 ◽  
Vol 50 (1) ◽  
pp. 158-159
Author(s):  
Warren J. Moberly ◽  
Daniel B. Miracle ◽  
S. Krishnamurthy
Keyword(s):  
Thermal Stresses ◽  
Load Transfer ◽  
Coefficient Of Thermal Expansion ◽  
Hot Isostatic Pressing ◽  
Matrix Composites ◽  
Ongoing Research ◽  
Aerospace Applications ◽  
Sic Fiber ◽  
The Matrix ◽  
Intermetallic Matrix Composites

Titanium-aluminum alloy metal matrix composites (MMC) and Ti-Al intermetallic matrix composites (IMC), reinforced with continuous SCS6 SiC fibers are leading candidates for high temperature aerospace applications such as the National Aerospace Plane (NASP). The nature of deformation at fiber / matrix interfaces is characterized in this ongoing research. One major concern is the mismatch in coefficient of thermal expansion (CTE) between the Ti-based matrix and the SiC fiber. This can lead to thermal stresses upon cooling down from the temperature incurred during hot isostatic pressing (HIP), which are sufficient to cause yielding in the matrix, and/or lead to fatigue from the thermal cycling that will be incurred during application, A second concern is the load transfer, from fiber to matrix, that is required if/when fiber fracture occurs. In both cases the stresses in the matrix are most severe at the interlace.

Numerical Study of Thermal Stresses in a Planar Solid Oxide Fuel Cell Stack

2017 ◽  
Author(s):  
Cun Wang ◽  
Tao Zhang ◽  
Cheng Zhao ◽  
Jian Pu
Keyword(s):  
Thermal Stress ◽  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Thermal Stresses ◽  
Coefficient Of Thermal Expansion ◽  
Numerical Study ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Compressive Loads ◽  
Cte Mismatch

A three dimensional numerical model of a practical planar solid oxide fuel cell (SOFC) stack based on the finite element method is constructed to analyze the thermal stress generated at different uniform temperatures. Effects of cell positions, different compressive loads, and coefficient of thermal expansion (CTE) mismatch of different SOFC components on the thermal stress distribution are investigated in this work. Numerical results indicate that the maximum thermal stress appears at the corner of the interface between ceramic sealants and cells. Meanwhile the maximum thermal stress at high temperature is significantly larger than that at room temperature (RT) and presents linear growth with the increase of operating temperature. Since the SOFC stack is under the combined action of mechanical and thermal loads, the distribution of thermal stress in the components such as interconnects and ceramic sealants are greatly controlled by the CTE mismatch and scarcely influenced by the compressive loads.

Multi-objective Numerical Investigation of a Generic Airblast Injector Design

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
Adam L. Comer ◽  
Timoleon Kipouros ◽  
R. Stewart Cant
Keyword(s):  
Design Space ◽  
Direct Injection ◽  
Design Studies ◽  
Lean Direct Injection ◽  
Analytical Work ◽  
Computational Fluid Dynamics Cfd ◽  
Aero Engines ◽  
Semi Empirical ◽  
Injector Design ◽  
Low Order

In combustor design for aero-engines, engineers face multiple opposing objectives with strict constraints. The trend toward lean direct injection (LDI) combustors suggests a growing emphasis on injector design to balance these objectives. Decades of empirical and analytical work have produced low-order methods, including semi-empirical and semi-analytical correlations and models of combustors and their components, but detailed modeling of injector and combustor behavior requires computational fluid dynamics (CFD). In this study, an application of low-order methods and published guidelines yielded generic injector and combustor geometries, as well as CFD boundary conditions of parameterized injector designs. Moreover, semi-empirical correlations combined with a numerical spray combustion solver provided injector design evaluations in terms of pattern factor, thermoacoustic performance, and certain emissions. Automation and parallel coordinate visualization enabled exploration of the dual-swirler airblast injector design space, which is often neglected in published combustor design studies.

Influence of Coating Layer to Reduce Thermal Stresses in Cylindrically Formed Metal Matrix Composites

2000 ◽  
Author(s):  
Fuat Okumus ◽  
Aydin Turgut ◽  
Erol Sancaktar
Keyword(s):  
Thermal Expansion ◽  
Metal Matrix Composites ◽  
Metal Matrix ◽  
Thermal Stresses ◽  
Coating Layer ◽  
Coefficient Of Thermal Expansion ◽  
Aluminum Matrix ◽  
Matrix Composites ◽  
Cylinder Model ◽  
Matrix Layer

Abstract In this study, the use of coating layers is investigated to reduce thermal stresses in the metal matrix composites which have a mismatch in coefficients of thermal expansions in fiber and matrix components. The thermoelastic solutions are obtained based on a three-cylinder model. It is shown that the effectiveness of the layer can be defined by the product of its coefficient of thermal expansion and thickness. Consequently, a compensating layer with a sufficiently high coefficient of thermal expansion can reduce the thermal stresses in the metal matrix. The study is based on a concentric three cylinder model isolating individual steel fibers surrounded with a coating layer and an aluminum matrix layer. Only monotonic cooling is studied.

Airfoil Deformation Analysis During Stator Repair Process

2003 ◽  
Author(s):  
Shazia M. Alam ◽  
Mahdy Allam ◽  
Chittaranjan Sahay
Keyword(s):  
Finite Element ◽  
Coefficient Of Thermal Expansion ◽  
Repair Process ◽  
Deformation Analysis ◽  
Analysis Tool ◽  
Element Analysis ◽  
Jet Engine ◽  
Inconel Alloys ◽  
Before And After ◽  
History Of

The compressor stator assembly of a jet engine normally consists of stainless steel and Inconel alloys. Nickel based alloys can be also used as brazing material. Mechanical distortion of the stator assembly components may result during the brazing process. The coefficient of thermal expansion of the component materials, thermal history of manufacturing and operation also contribute to the stator deformation. The purpose of this work is to study the factors causing the distortion in vane stages. The study uses Finite Element Analysis tool ANSYS 5.7 for modeling the engine stator assembly. A finite element structural analysis of a single airfoil model is conducted at various repair points to assess the airfoil deformation and stress levels, before and after the brazing process. It is then used to identify materials and brazing parameters responsible for the observed distortion. The model analyzed shows general agreement between the numerical results and observations from the repair process. The probable causes of distortion are found and recommendations for fixing the distortion problem are also made.

A Study on the Thermoelastic Analysis in Shear Deformable Discontinuous Composites

2004 ◽  
Vol 261-263 ◽  
pp. 645-650
Author(s):  
Hong Gun Kim
Keyword(s):  
Thermal Stresses ◽  
Volume Fraction ◽  
Coefficient Of Thermal Expansion ◽  
Fiber Composite ◽  
Element Model ◽  
Short Fiber ◽  
Elastic Stresses ◽  
Fiber Aspect Ratio ◽  
The Matrix ◽  
Lag Model

A stress analysis has been performed to evaluate the thermally induced elastic stresses which can develop in a short fiber composite due to coefficient of thermal expansion (CTE) mismatch. An axisymmetric finite element model with the constraint between cells has implemented to find the magnitude of thermoelastic stresses in the fiber and the matrix as a function of volume fraction, CTE ratio, modulus ratio, and fiber aspect ratio. It was found that the matrix end regions fall under significant thermal stresses that have the same sign as that of the fibers themselves. Furthermore, it was found that the stresses vary along the fiber and fiber end gap in the same manner as that obtained in a shear-lag model during non-thermal mechanical loading.

A General Solution for the Elastoplastic Thermal Stresses in a Strain-Hardening Plate With Arbitrary Material Properties

1962 ◽  
Vol 29 (1) ◽  
pp. 151-158 ◽  
Author(s):  
A. Mendelson ◽  
S. W. Spero
Keyword(s):  
Thermal Expansion ◽  
General Solution ◽  
Strain Hardening ◽  
Material Properties ◽  
Thermal Stresses ◽  
Coefficient Of Thermal Expansion ◽  
Stress And Strain ◽  
Linear Strain ◽  
Hardening Material ◽  
General Method

A general method is presented for obtaining the elastoplastic stress and strain distributions in a thermally stressed plate of a strain-hardening material with temperature-varying modulus, yield point, and coefficient of thermal expansion. It is shown that for linear strain-hardening the solution can often be obtained in closed form. It is indicated that the error due to neglecting strain-hardening may sometimes be appreciable. The assumption that the total strain remains the same as that computed elastically (strain invariance) often leads to smaller errors than the neglect of strain-hardening.

Addressing Next Generation Packaging and IoT with Glass Solutions

2017 ◽  
Vol 2017 (DPC) ◽  
pp. 1-19 ◽  
Author(s):  
Aric Shorey ◽  
Rachel Lu ◽  
Gene Smith
Keyword(s):  
Mobile Communications ◽  
Mechanical Performance ◽  
Coefficient Of Thermal Expansion ◽  
Cost Effective ◽  
Electronics Packaging ◽  
Next Generation ◽  
High Frequencies ◽  
Glass Forming ◽  
The Internet Of Things ◽  
Electrical Loss

New requirements are emerging in electronics packaging. The ever-growing need for solutions for mobile communications and sensors that address the Internet of Things (IoT) provide interesting new challenges. RF applications strive to move to higher frequency bands, fan-out technology is being leveraged as an effective way to address interconnect demands, and there is a continuous search for more cost-effective solutions for difficult packaging challenges. Glass provides numerous opportunities to address these needs. As an insulator, glass has low electrical loss, particularly at high frequencies. The relatively high stiffness and ability to adjust coefficient of thermal expansion helps optimize warp in glass core substrates, bonded stacks leveraging TGV and in carrier applications. Glass forming processes allow the potential to both form in panel format as well as at thicknesses as low as 100 um, giving opportunities to optimize or eliminate current manufacturing methods and address packaging challenges in a cost effective way. We will provide the latest demonstrations of electrical, thermal and mechanical performance and reliability, describe areas where glass is being leveraged to achieve goals of next generation products and how properties of different glass types are leveraged by application.

Reliability Assessment of a New Power Electronics Packaging Material: Silver Diamond Composite

2013 ◽  
Vol 10 (2) ◽  
pp. 54-58 ◽  
Author(s):  
M. Faqir ◽  
J. W. Pomeroy ◽  
T. Batten ◽  
T. Mrotzek ◽  
S. Knippscheer ◽  
...  
Keyword(s):  
Thermal Cycling ◽  
Power Electronics ◽  
Structural Changes ◽  
Coefficient Of Thermal Expansion ◽  
Base Plate ◽  
Electronics Packaging ◽  
Case Scenario ◽  
Worst Case ◽  
New Material ◽  
Work Samples

A reliability analysis of silver diamond composites in terms of both thermal and mechanical properties is presented. This new material is an attractive solution for power electronics packaging, because an improvement of 50% in terms of thermal management and channel temperature can be obtained when using silver diamond composites as a base plate in packages compared with the more traditionally used materials such as CuW. However, to date, little is known about the reliability of this new material, such as changes induced in its properties by thermal cycling. Assessment of the reliability of silver diamond composites is the aim of this work. Samples were submitted to 10 thermal cycles from room temperature to 350°C, and subsequently, a further 500 cycles of thermal shock as well as thermal cycling from −55°C to 125°C following typical standards used in space and military applications. In the worst-case scenario, thermal conductivity only decreased from 830 W/m·K to ∼700 W/m·K. An increase in the coefficient of thermal expansion and a change in diamond stress, were also observed after thermal cycling. Some structural modifications at the silver-diamond interface were found to be the underlying reason for the observed material properties change. These structural changes take place after the initial thermal cycling, and are constant thereafter. Changes found in thermal properties are satisfactory for enabling a significant improvement to standard CuW packaging materials.

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