Effect of Design Variables on Voids and Thermal Performance of QFN Packages

2007 ◽  
Author(s):  
Farbod Askari ◽  
Leila Jannesari Ladani ◽  
Abhijit Dasgupta ◽  
Matti Rahko ◽  
Jussi Sarkka
Keyword(s):  
Fractional Factorial ◽  
Area Fraction ◽  
Aperture Size ◽  
Element Analysis ◽  
Analysis Techniques ◽  
Design Variables ◽  
Factorial Matrix ◽  
Different Types ◽  
Void Area ◽  
Area Percentage

The objective of this study is to empirically investigate the dependence of solder voids and related interconnect defects in QFN packages, on such design variables as stencil aperture pattern and size, as well as quantity and location of thermal vias. A non-traditional fractional-factorial matrix was used for this study. The QFN packages produced by implementing this experiment were analyzed using destructive and nondestructive failure analysis techniques. The effect of design variables on different types of defects such as voids, and taper were evaluated. This study showed that stencil aperture size influences void area percentage the most in comparison with other design variables. An optimal stencil configuration was proposed based on void area fraction calculations. A 2-D steady-state finite element analysis was then conducted to parametrically evaluate the effect of solder voids on the performance of thermal vias under QFN thermal pads. The model confirmed that the performance of thermal vias is not very sensitive to void area fraction.

Interaction Effect of Voids and Standoff Height on Thermo-Mechanical Durability of BGA Solder Joints

2009 ◽  
Author(s):  
Leila J. Ladani ◽  
Jafar Razmi
Keyword(s):  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Solder Joints ◽  
Interactive Effect ◽  
Area Fraction ◽  
Element Analysis ◽  
Load Bearing ◽  
Mechanical Durability ◽  
Void Area

This paper documents simulation studies on interactive effect of standoff height and void volume on thermo-mechanical durability of Ball Grid Array (BGA) solder joints using a 3D visco-plastic finite element analysis. SE software was used to find the optimized shape of the solder joints and standoff height by minimizing the surface energy as voids with different sizes were placed in solder balls. A global-local modeling approach was then utilized to model thermo-mechanical durability of voided solder joints. Void area fraction ranges of 14% to 40% were analyzed. A nonmonotonic behavior of durability versus void area fraction was observed. The results showed that if the void is completely inside the solder ball and has no interface with the boundaries of the joint, it does not have a detrimental effect and even improves the durability as the void size increases. However, voids located at the interface of solder joint and copper pads were found very detrimental to durability. Factors such as load bearing area, stress concentration factor and overall compliance of the structure were found responsible for the non-monotonic behavior of the joints. An analytical micro-mechanics approach was used to calculate the compliance of the structure and a nonmonotonic trend in phase with the durability trend was observed. The stress concentration factor also showed the same non monotonic trend. Rise of these two factors for the void interfacing with copper pads in addition to the decreased load bearing area effect resulted in drastic decrease in durability.

Finite Element Modeling for Steel Cord Analysis in Radial Tires

2013 ◽  
Vol 41 (1) ◽  
pp. 60-79 ◽  
Author(s):  
Wei Yintao ◽  
Luo Yiwen ◽  
Miao Yiming ◽  
Chai Delong ◽  
Feng Xijin
Keyword(s):  
Finite Element ◽  
High Efficiency ◽  
Force Measurement ◽  
Three Dimensional ◽  
Local Stress ◽  
Tension Force ◽  
Center Line ◽  
Element Analysis ◽  
Design Variables ◽  
Steel Cord

ABSTRACT: This article focuses on steel cord deformation and force investigation within heavy-duty radial tires. Typical bending deformation and tension force distributions of steel reinforcement within a truck bus radial (TBR) tire have been obtained, and they provide useful input for the local scale modeling of the steel cord. The three-dimensional carpet plots of the cord force distribution within a TBR tire are presented. The carcass-bending curvature is derived from the deformation of the carcass center line. A high-efficiency modeling approach for layered multistrand cord structures has been developed that uses cord design variables such as lay angle, lay length, and radius of the strand center line as input. Several types of steel cord have been modeled using the developed method as an example. The pure tension for two cords and the combined tension bending under various loading conditions relevant to tire deformation have been simulated by a finite element analysis (FEA). Good agreement has been found between experimental and FEA-determined tension force-displacement curves, and the characteristic structural and plastic deformation phases have been revealed by the FE simulation. Furthermore, some interesting local stress and deformation patterns under combined tension and bending are found that have not been previously reported. In addition, an experimental cord force measurement approach is included in this article.

DESIGN AND THERMAL ANALYSIS OF BRAKE ROTOR WITH DIFFERENT MATERIALS

2020 ◽  
Vol 15 (2) ◽  
Author(s):  
Sugunarani S ◽  
Santhosh V
Keyword(s):  
Temperature Distribution ◽  
Heat Dissipation ◽  
Brake Disc ◽  
Element Analysis ◽  
Analysis Techniques ◽  
Engineering Software ◽  
The Finite Element Analysis ◽  
Brake Rotor ◽  
Grey Cast ◽  
Aluminium Metal

This work deals with the analysis of heat generation and dissipation in the disc brake of a car during braking and the following release period by using computer-aided engineering software for three different materials of the rotor disc and brake pad. The objective of this work is to analyze the temperature distribution of rotor disc during operation using COMSOL Multiphysics. The work uses the finite element analysis techniques to calculate and predict the temperature distribution on the brake disc and to identify the critical temperature of the brake rotor disc. Conduction, convection and radiation of heat transfer have been analyzed. The results obtained from the analysis indicates that different material on the same retardation of the car during braking shows different temperature distribution. A comparative study was made between grey cast iron (GCI), Aluminium Metal Matrix Composite (AMMC), Alloy steel materials are used for brake disc and the best material for making brake disc based on the rate of heat dissipation have been suggested.

Probabilistic finite element analysis in heat transfer to a nuclear fuel rod bumper support

2004 ◽  
Vol 218 (12) ◽  
pp. 1499-1505
Author(s):  
Rama Subba Reddy Gorla
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Nuclear Fuel ◽  
Cost Effective ◽  
Distribution Functions ◽  
Cumulative Distribution ◽  
Element Analysis ◽  
Transfer Rates ◽  
Fuel Rod ◽  
Design Variables

Heat transfer from a nuclear fuel rod bumper support was computationally simulated by a finite element method and probabilistically evaluated in view of the several uncertainties in the performance parameters. Cumulative distribution functions and sensitivity factors were computed for overall heat transfer rates due to the thermodynamic random variables. These results can be used to identify quickly the most critical design variables in order to optimize the design and to make it cost effective. The analysis leads to the selection of the appropriate measurements to be used in heat transfer and to the identification of both the most critical measurements and the parameters.

MODEL-FREE FUNCTIONAL MRI ANALYSIS USING TOPOGRAPHIC INDEPENDENT COMPONENT ANALYSIS

2004 ◽  
Vol 14 (04) ◽  
pp. 217-228 ◽  
Author(s):  
ANKE MEYER-BÄSE ◽  
OLIVER LANGE ◽  
AXEL WISMÜLLER ◽  
HELGE RITTER
Keyword(s):  
Independent Component Analysis ◽  
Slight Modification ◽  
Component Analysis ◽  
Independent Component ◽  
Self Organizing Map ◽  
Analysis Techniques ◽  
Model Free ◽  
Temporal Domain ◽  
Different Types ◽  
Fmri Analysis

Data-driven fMRI analysis techniques include independent component analysis (ICA) and different types of clustering in the temporal domain. Since each of these methods has its particular strengths, it is natural to look for an approach that unifies Kohonen's self-organizing map and ICA. This is given by the topographic independent component analysis. While achieved by a slight modification of the ICA model, it can be at the same time used to define a topographic order (clusters) between the components, and thus has the usual computational advantages associated with topographic maps. In this contribution, we can show that when applied to fMRI analysis it outperforms FastICA.

The Finite Element Analysis and the Multi-Objective Optimization Design of Spindle Systems of CNC Gantry Machine Tools

2016 ◽  
Vol 693 ◽  
pp. 243-250
Author(s):  
Zhi Zhong Guo ◽  
Yun Shun Zhang ◽  
Shi Hao Liu
Keyword(s):  
Machine Tools ◽  
Optimization Design ◽  
Multi Objective Optimization ◽  
Element Analysis ◽  
Multi Objective ◽  
Vibration Resistance ◽  
Design Variables ◽  
Force Coupling ◽  
The Finite Element Analysis ◽  
Spindle Structure

It is discovered that the vibration resistance of spindle systems needs to be improved based on the statics analysis, modal analysis and heating-force coupling analysis of spindle systems of CNC gantry machine tools. The design variables of optimization are set according to sensitivity analysis, multi-objective and dynamic optimization design is realized and its designing scheme is gained for spindle structure. The research results show that vibration resistance can be improved without change of the quality and static property of spindle systems of CNC gantry machine tools.

Practical Procedures for Technical and Economic Investigation of Ship Structural Details

1981 ◽  
Vol 18 (01) ◽  
pp. 51-68
Author(s):  
Donald Liu ◽  
Abram Bakker
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Concentrations ◽  
Element Analysis ◽  
Analysis Techniques ◽  
Structural Problems ◽  
Analysis Technique ◽  
The Finite Element Analysis ◽  
Structural Details

Local structural problems in ships are generally the result of stress concentrations in structural details. The intent of this paper is to show that costly repairs and lay-up time of a vessel can often be prevented, if these problem areas are recognized and investigated in the design stages. Such investigations can be performed for minimal labor and computer costs by using finite-element analysis techniques. Practical procedures for analyzing structural details are presented, including discussions of the results and the analysis costs expended. It is shown that the application of the finite-element analysis technique can be economically employed in the investigation of structural details.

Enhanced Vibration Control of Ultrasonic Tooling Using Finite Element Analysis

1991 ◽  
Author(s):  
Kevin O’Shea
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cross Sections ◽  
High Frequency ◽  
Excellent Correlation ◽  
Accurate Identification ◽  
Element Analysis ◽  
Optimum Configuration ◽  
Slot Length ◽  
Design Variables

Abstract The use of finite element analysis (FEA) in high frequency (20–40 kHz), high power ultrasonics to date has been limited. Of paramount importance to the performance of ultrasonic tooling (horns) is the accurate identification of pertinent modeshapes and frequencies. Ideally, the ultrasonic horn will vibrate in a purely axial mode with a uniform amplitude of vibration. However, spurious resonances can couple with this fundamental resonance and alter the axial vibration. This effect becomes more pronounced for ultrasonic tools with larger cross-sections. The current study examines a 4.5″ × 6″ cross-section titanium horn which is designed to resonate axially at 20 kHz. Modeshapes and frequencies from 17–23 kHz are examined experimentally and using finite element analysis. The effect of design variables — slot length, slot width, and number of slots — on modeshapes and frequency spacing is shown. An optimum configuration based on the finite element results is prescribed. The computed results are compared with actual prototype data. Excellent correlation between analytical and experimental data is found.

The Unified Theory of Tubesheet Design - Part III: Comparison with ASME Method and Case Study

2021 ◽  
Author(s):  
Hong-Song Zhu ◽  
Jinguo Zhai ◽  
Guo-Yan Zhou
Keyword(s):  
Heat Exchangers ◽  
Numerical Comparison ◽  
Unified Theory ◽  
Element Analysis ◽  
Theoretical Comparison ◽  
Comparison Results ◽  
Different Types ◽  
Special Case ◽  
Simplified Mechanical Model

Abstract Based on the unified theory of tubesheet (TS) design for fixed TS heat exchangers (HEX), floating head and U-tube HEX presented in Part I and Part II, theoretical and numerical comparisons with ASME method are performed in this paper as Part III. Theoretical comparison shows that ASME method can be obtained from the special case of the simplified mechanical model of the unified theory. Numerical Comparison results indicate that predictions given by the unified theory agree well with finite element analysis (FEA), while ASME results are not accurate or not correct. Therefore, it is concluded that the unified theory deals with different types of HEX in equal detail with confidence to predict design stresses.

Sign in / Sign up

Export Citation Format

Share Document