Stress Analysis of Hygrothermal Delamination of Quad Flat No-Lead (QFN) Packages

2008 ◽  
Author(s):  
Minshu Zhang ◽  
S. W. Ricky Lee ◽  
Xuejun Fan
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Thermal Loading ◽  
Element Model ◽  
Interfacial Stress ◽  
Moisture Distribution ◽  
Superposition Method ◽  
Element Analysis ◽  
Interfacial Delamination ◽  
Simulation And Experiment

Interfacial delamination is a major reliability issue of Quad Flat No-lead (QFN) packages under the JEDEC-MSL preconditioning and reflow process. Failures will occur when the hygrothermal stress exceeds the interfacial strength. Simulation based on finite element model is a popular method for studying the failure mechanism. However, the non-accurate material properties and the lack of experiment validations always constrain the Finite Element Analysis (FEA) at the artificial parametric study stage. To further investigate the interfacial delamination, a complex system including both simulation and experiment validation is established in this study. A dummy QFN is fabricated first as the test vehicle for the subsequent study. Then the related finite element model is built to reveal the interfacial stress distribution when the packages are subjected to the pure thermal loading and hygrothermal loading, respectively. Once the interfacial stress is derived, the strength approach is applied here to indicate the high risk area where delamination will occur. Finally, the analyses from simulation are verified by Moisture Sensitivity Level (MSL) tests using dummy samples. In this paper, a superposition method is used to integrate the thermo-mechanical and hygro-mechanical stress, with considering the non-uniform moisture distribution during reflow. Such a method is different from the previously method in literature. Results show that the shear stress is dominant along all the interfaces. From the comparison between simulation and experiments, the strength approach is applied to evaluate the package reliability successfully. Both simulation and experiment results show that the molding compound/lead-frame interface around the junction of die attach fillet would be the initiation of delamination.

Three-Dimensional Finite Element Analysis of Mixed-Mode Interfacial Delamination for the Pull-Off Test

2007 ◽  
Author(s):  
Zuo Sun ◽  
David A. Dillard
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Finite Element Model ◽  
Mixed Mode ◽  
Three Dimensional ◽  
Element Model ◽  
Element Analysis ◽  
Interfacial Delamination ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

A three-dimensional nonlinear finite element analysis model is presented to study mixed-mode interfacial delamination for a pull-off test consisting of a thin film strip debonded from a glass substrate. Since the strain energy release rates of all three modes (Mode I, Mode II, and Mode III) and the mode mixities vary along the width of the debond front, prediction of the in-situ shape of the debond front remains an interesting and challenging topic. A cohesive zone model is incorporated into the three-dimensional finite element model to predict the interfacial crack propagation profile for the film deformation regime ranging from bending plate to stretching membrane. This three-dimensional finite element model is found to provide additional insights for interfacial delamination for the pull-off test.

Torsional Analysis of a Steel Cord-Rubber Tire Belt Structure

1996 ◽  
Vol 24 (4) ◽  
pp. 339-348 ◽  
Author(s):  
R. M. V. Pidaparti
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Composite Structures ◽  
Three Dimensional ◽  
Element Model ◽  
Torsional Stiffness ◽  
Element Analysis ◽  
Rubber Belt ◽  
Steel Cord ◽  
Torsional Analysis

Abstract A three-dimensional (3D) beam finite element model was developed to investigate the torsional stiffness of a twisted steel-reinforced cord-rubber belt structure. The present 3D beam element takes into account the coupled extension, bending, and twisting deformations characteristic of the complex behavior of cord-rubber composite structures. The extension-twisting coupling due to the twisted nature of the cords was also considered in the finite element model. The results of torsional stiffness obtained from the finite element analysis for twisted cords and the two-ply steel cord-rubber belt structure are compared to the experimental data and other alternate solutions available in the literature. The effects of cord orientation, anisotropy, and rubber core surrounding the twisted cords on the torsional stiffness properties are presented and discussed.

scholarly journals Analysis for Wrinkling Behavior of Girth-Welded Line Pipe

1996 ◽  
Author(s):  
Luiz T. Souza ◽  
David W. Murray
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Finite Element Model ◽  
Internal Pressure ◽  
Experimental Test ◽  
Element Model ◽  
Element Analysis ◽  
Line Pipe ◽  
New Era ◽  
Analytical Tools

The paper presents results for finite element analysis of full-sized girth-welded specimens of line pipe and compares these results with the behavior exhibited by test specimens subjected to constant axial force, internal pressure and monotonically increasing curvatures. Recommendations for the ‘best’ type of analytical finite element model are given. Comparisons between the behavior predicted analytically and the observed behavior of the experimental test specimens are made. The mechanism of wrinkling is explained and the evolution of the deformed configurations for different wrinkling modes is examined. It is concluded that the analytical tools now available are sufficiently reliable to predict the behavior of pipe in a manner that was not previously possible and that this should create a new era for the design and assessment of pipelines if the technology is properly exploited by industry.

scholarly journals A Novel Method for Tooth Bending Stress Calculation of Gears With Asymmetric Teeth

2021 ◽  
Author(s):  
Oguz DOGAN ◽  
Celalettin YUCE ◽  
Fatih KARPAT
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Experimental Studies ◽  
Element Model ◽  
Bending Stress ◽  
Element Analysis ◽  
Stress Calculation ◽  
Bending Stresses ◽  
New Equation ◽  
Asymmetric Factor

Abstract Today, gear designs with asymmetric tooth profiles offer essential solutions in reducing tooth root stresses of gears. Although numerical, analytical, and experimental studies are carried out to calculate the bending stresses in gears with asymmetric tooth profiles a standard or a simplified equation or empirical statement has not been encountered in the literature. In this study, a novel bending stress calculation procedure for gears with asymmetric tooth profiles is developed using both the DIN3990 standard and the finite element method. The bending stresses of gears with symmetrical profile were determined by the developed finite element model and was verified by comparing the results with the DIN 3990 standard. Using the verified finite element model, by changing the drive side pressure angle between 20° and 30° and the number of teeth between 18 and 100, 66 different cases were examined and the bending stresses in gears with asymmetric profile were determined. As a result of the analysis, a new asymmetric factor was derived. By adding the obtained asymmetric factor to the DIN 3390 formula, a new equation has been derived to be used in tooth bending stresses of gears with asymmetric profile. Thanks to this equation, designers will be able to calculate tooth bending stresses with high precision in gears with asymmetric tooth profile without the need for finite element analysis.

Simulation of Thermo-Mechanical Models for Hot Formed Parts by Numerical Experiments

2014 ◽  
Vol 663 ◽  
pp. 668-674
Author(s):  
Azman Senin ◽  
Zulkifli Mohd Nopiah ◽  
Muhammad Jamhuri Jamaludin ◽  
Ahmad Zakaria
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Prediction Accuracy ◽  
Research Work ◽  
Deformation Characteristic ◽  
Element Model ◽  
Forming Limit ◽  
Prototype Model ◽  
New Production ◽  
Element Analysis

The Finite-Element Analysis (FEA) is a prediction methodology that facilitates product designers produced the part design with manufacturing focused. With the similar advantages, manufacturing engineers are capable of build the first actual car model from the new production Draw Die. This approach has eliminated the requirement to manufacture the prototype model from soft tool parts and soft tool press die. However, the prediction accuracy of FEA is a major topic of research work in automotive sector's practitioners and academia as current accuracy level is anticipated at 60%. The objective of works is to assess the prediction accuracy on deformation results from mass production stamped parts. The Finite-element model is developed from the CAD data of the production tools. Subsequently, finite-element model for production tools is discretized with shell elements to avoid computation errors in the simulation process. The sheet blank material with 1.5 mm and 2.0 mm thickness is discredited by shell (2D modeling) and solid elements (3D modeling) respectively. The input parameters for the simulation model for both elements are attained from the actual setup at Press Machine and Production Tool. The analysis of deformation and plastic strain are performed for various setup parameters. Finally, the deformation characteristic such as Forming Limit Diagram (FLD) and thinning are compared for all simulated models.

Finite Element Analysis of Tandem Rubber O-Ring Sealing Structure at the End of Shaft

2013 ◽  
Vol 774-776 ◽  
pp. 25-29
Author(s):  
Cong Fang Hu ◽  
Yuan Qiang Tan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Compression Rate ◽  
Element Analysis ◽  
Uniform Compression ◽  
Friction Factors ◽  
Sealing Performance ◽  
Sealing Failure

Based on the tandem sealing structure at the end of the shaft,a finite element model of rubber O-rings has been established and the sealing performance of rubber O-ring has been analyzed. There is an un-uniform compression among these O-rings which lead to the sealing failure. Under different friction factors, several groups of the rubber O-rings have been analyzed, finding that the friction factor is the reason of un-uniform compression. The effect of different average compression rate has been investigated, which has been integrated in the sealing criteria for the tandem O-rings, providing a reference for the optimization of tandem sealing structure at the end of the shaft. According to the sealing criteria for a single O-ring, the sealing criteria for the tandem O-rings is built.

Finite Element Analysis of Mechanics Property on Memory Alloy Patella Claws with Anti-Shearing Force

2014 ◽  
Vol 635-637 ◽  
pp. 507-510
Author(s):  
Dong Peng Du ◽  
Zhe Wu ◽  
Juan Xing ◽  
Xiao Yan Gong ◽  
Xiang Wen Miu ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Mechanical Performance ◽  
Tensile Force ◽  
Research Result ◽  
Element Model ◽  
3D Models ◽  
Shearing Force ◽  
Maximum Displacement ◽  
Element Analysis

When strong exercise on human being body, respectively, under knees 30°, 60°,90°, using PRO/E5.0 software to establish the transverse patella fracture and anti-shearing force patella claws 3D models, then the two structure models were assembled and imported into ABAQUS10.1 software to establish the finite element model of patellar fracture fixed within patella claw, and analyzed the mechanical performance in perforce finite element model. Under the same boundary conditions, the maximum displacement and deformation of each components were different at every flexion angle. Compared with anti-shearing force patella claw and AO tensile force girdle, the patella claw with stronger resistance to tension and anti-shearing force was more stable. Deformation and displacement of patella claw in accordance with biomechanical research result that is needed by clinical. Its stability will satisfy clinical requirements for functional exercise.

Finite Element Analysis of Structural Strength of Concrete Mixing Truck’s Frame

2014 ◽  
Vol 945-949 ◽  
pp. 1143-1149
Author(s):  
Hai Xia Sun ◽  
Hua Kai Wei ◽  
Xiao Fang Zhao ◽  
Jia Rui Qi
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Finite Element Model ◽  
Structural Strength ◽  
Element Model ◽  
Basic Element ◽  
Operating Conditions ◽  
Frame Structure ◽  
Element Analysis ◽  
The Finite Element Model

The finite element model of the concrete mixing truck’s frame is builded by using shell as basic element, and the process of building the finite element model of the balance suspension is introduced in detail. Based on this, frame’s stress on five types of typical operating conditions are calculated by using the finite element analysis software, NASTRAN, and results can show the dangerous position and the maximum stress position on the frame. The analysis result on structural strength can provide the basis for further improving the frame structure.

Dynamic Characteristics and Finite Element Model Updating of Micromachined Torsion Structures

2013 ◽  
Vol 284-287 ◽  
pp. 1831-1835
Author(s):  
Wei Hsin Gau ◽  
Kun Nan Chen ◽  
Yunn Lin Hwang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Finite Element Model ◽  
Model Updating ◽  
Speckle Pattern ◽  
Element Model ◽  
Mode Shapes ◽  
Electronic Speckle Pattern Interferometry ◽  
Finite Element Model Updating ◽  
Element Analysis

In this paper, two experimental techniques, Electronic Speckle Pattern Interferometry and Stroboscopic Interferometry, and two different finite element analysis packages are used to measure or to analyze the frequencies and mode shapes of a micromachined, cross-shaped torsion structure. Four sets of modal data are compared and shown having a significant discrepancy in their frequency values, although their mode shapes are quite consistent. Inconsistency in the frequency results due to erroneous inputs of geometrical and material parameters to the finite element analysis can be salvaged by applying the finite element model updating procedure. Two updating cases show that the optimization sequences converge quickly and significant improvements in frequency prediction are achieved. With the inclusion of the thickness parameter, the second case yields a maximum of under 0.4% in frequency difference, and all parameters attain more reliable updated values.

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