Groove Geometry and Mold Shrinkage Effects on Die Stress in Flip Chip Molded BGAs (FCMBGA)

2013 ◽  
Vol 2013 (DPC) ◽  
pp. 000455-000470
Author(s):  
Bora Baloglu ◽  
Miguel Jimarez ◽  
Ahmer Syed
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Flip Chip ◽  
Element Model ◽  
Shear Stresses ◽  
Back Side ◽  
Molding Process ◽  
Finite Elements Analysis ◽  
Design Guideline ◽  
Structural Support

Exposed die flip chip molded BGA (FCMBGA) packages are preferred for their improved thermal performance and reduced system cost. In this package type, mold compound replaces the traditional capillary underfill and also provides a better stiffening option for the package without the need for additional structural support such as lid and/or stiffening ring. In addition, it allows better utilization of the board real estate as the passive components can be placed closer to the die. Groove or an undercut is the shape of the mold around the exposed die that is formed during the molding process. To ensure a mold-free top surface of the die, a seal (soft insert) that has a larger surface area than the die is being used to cover the die top surface. This larger portion of the seal outlines the groove geometry when it is compressed on top of the die. Seal size can be designed to establish certain groove geometry. Thus, it is important to characterize/understand the effects of the groove geometry as it is a design parameter and can be adjusted to create more robust molded packages. In this study, specific groove width and depth values for various package configurations are investigated using finite elements analysis, FEA. Initially, a detailed finite element model is prepared and warpage simulation is performed. Model correlation to the actual Shadow Moiré is obtained. Then, using the correlated finite element model, die back side stress and shear stresses, where die faces mold compound, are obtained for a thermal cool down simulation from the molding temperature. Mold compound shrinkage is also considered by using an adjusted thermal expansion coefficient value. As a validation study, a test mold chase/tool for varying insert sizes has been designed and, molded packages with different groove geometries and different mold compounds were build. Using the correlation between the test data and the simulation results an order of importance (based on the groove geometry parameters and mold compound's material properties) will be presented which then, can be used as a design guideline to change the groove geometry to produce more robust molded packages.

Reduction of Free-Edge Stress Concentration

1985 ◽  
Vol 52 (4) ◽  
pp. 801-805 ◽  
Author(s):  
P. R. Heyliger ◽  
J. N. Reddy
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Finite Element Model ◽  
Three Dimensional ◽  
Element Model ◽  
Free Edge ◽  
Shear Stresses ◽  
Normal Stresses ◽  
Interlaminar Shear ◽  
Three Dimensional Elasticity

A quasi-three dimensional elasticity formulation and associated finite element model for the stress analysis of symmetric laminates with free-edge cap reinforcement are described. Numerical results are presented to show the effect of the reinforcement on the reduction of free-edge stresses. It is observed that the interlaminar normal stresses are reduced considerably more than the interlaminar shear stresses due to the free-edge reinforcement.

A Finite Element Model for Elastic and Slip Responses of Fusion Magnets

1980 ◽  
Vol 102 (2) ◽  
pp. 219-225
Author(s):  
T. Y. Chang ◽  
H. Suzuki ◽  
M. Reich
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Bonding Strength ◽  
Element Model ◽  
Type Model ◽  
Shear Stresses ◽  
Homogenization Procedure ◽  
Numerical Examples ◽  
Proposed Model ◽  
Interlayer Slip

A finite element model to simulate the elastic and slip responses of fusion magnets under operating loads is proposed. To represent the elastic actions, a material homogenization procedure based on the existing composite technology was applied to obtain the effective stress strain relations for the heterogeneous, laminated magnets. In addition, a friction-type model was utilized to simulate the interlayer slip of the magnets when the shear stresses reach the bonding strength of the adhesives. Numerical examples are given to demonstrate the applicability of the proposed model.

NUMERICAL ANALYSIS OF AXIALLY LOADED COLD-FORMED STEEL BUILT-UP BOX SECTION

2016 ◽  
Vol 3 (2) ◽  
Author(s):  
T.C.H. Ting ◽  
H.H. Lau ◽  
M.S. Joo
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Construction Industry ◽  
Element Model ◽  
Design Code ◽  
Design Guideline ◽  
Box Section ◽  
Current Design ◽  
Cold Formed Steel ◽  
The Finite Element Model

Built up box section is a doubly symmetrical section in which two C-channel connected at the flange using self-drilling screw. They are generally used in the construction industry to obtain higher rigidity, when a single section is not sufficient. Despite being widely used in the construction industry, there are limited studies on built-up box section. Moreover, the current design code does not provide clear design guideline for the calculation of built-up box section. Therefore, research on the built-up box section is important. This paper presents a finite element model to predict the compressive strength and simulate the behavior of cold-formed steel built-up box section. The finite element model was developed using ABAQUS CAE/6.14. Comparison of the finite element and experimental results showed good correlation. The model well predicted the behavior of the built-up box column.

1F14 Exploration of design guideline of a supportive underwear to improve pelvic floor relaxation by a finite element model of the buttocks

2016 ◽  
Vol 2016.28 (0) ◽  
pp. _1F14-1_-_1F14-5_
Author(s):  
Tomohiro Nishiki ◽  
Daisuke Tawara ◽  
Tetsuya Tsujikami ◽  
Sanae Ninomiya ◽  
Hisayo Okayama ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Pelvic Floor ◽  
Element Model ◽  
Design Guideline

The Prediction Method on Warpage of Injection Molded Parts

2011 ◽  
Vol 317-319 ◽  
pp. 211-214
Author(s):  
Tong Chen Chang ◽  
Hong Yu Zhu ◽  
Hai Hong Wu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Degrees Of Freedom ◽  
Prediction Method ◽  
Element Model ◽  
Thermal Shrinkage ◽  
Injection Molding Process ◽  
Molding Process ◽  
Molded Parts ◽  
Rotational Degrees Of Freedom

Warpage is a common defect resulted from uneven thermal shrinkage during injection molding process. In this paper, the authors investigated finite element method to predict the warpage of injection moldings with thin shell theory. In order to improve calculating accuracy, discrete Kirchhoff element combined membrane element with rotational degrees of freedom was used to build finite element model. The results predicted with this model were compared with experimental data. The results showed that this finite element model was effective to increase the prediction accuracy of the warpage because of bring transfer matrices to improve the element accuracy.

A Full-Scale 3D Finite Element Analysis for No-Underfill Flip Chip Package

2002 ◽  
Author(s):  
S. M. Hsu ◽  
J. C. Lin ◽  
K. N. Chiang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Flip Chip ◽  
Computation Time ◽  
Element Model ◽  
Organic Substrate ◽  
Full Scale ◽  
Element Analysis ◽  
3D Finite Element ◽  
3D Finite Element Model

This research establishes a micro-macro 3D finite element model for no underfill flip chip BGA package. The no underfill package uses a ceramic-like (CTE close to silicon) material mounted on the backside of the flip chip substrate to constrain the thermal expansion of the organic substrate and enhance the reliability of the solder joint. This work attempts to design a constrained structure to enhance the reliability of the no underfill flip chip package. For the special design of constrained structure, a full-scale 3D finite element model is needed to investigate some mechanical behaviors that cannot be revealed by the 2D finite element model. However, to establish a full-scale 3D finite element model, the large computation time is an issue. The equivalent beam concept is adopted in this research to overcome this drawback of the finite element models. The results indicate that the equivalent beam concept is a feasible methodology for reducing the computation time of the 3D finite element model. Further, the new design structure could improve package reliability, increase manufacturing throughput and thermal performance, and maintain reworkability of the flip chip structure.

Bending Analysis of Composite Sandwich Plates with Flexible Core Using 3D Finite Element Method

2011 ◽  
Vol 110-116 ◽  
pp. 1229-1236
Author(s):  
Mohammad Mahdi Kheirikhah ◽  
Seyyed Mohammad Reza Khalili
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Transverse Shear ◽  
Sandwich Plate ◽  
Element Model ◽  
Shear Stresses ◽  
Sandwich Plates ◽  
Normal Strain ◽  
Bending Analysis ◽  
Transverse Shear Stresses

Sandwich plates have been extensively used in many engineering applications such as automotive and aerospace. In the present paper, an accurate finite element model is presented for bending analysis of soft-core rectangular sandwich plates. The sandwich plate is composed of three layers: top and bottom skins and core layer. The core is assumed as a soft orthotropic material and skins are assumed generally unequal laminated composites. Finite element model of the problem has been constructed in the ANSYS 11.0 standard code area. Continuity conditions of transverse shear stresses at the interfaces are satisfied as well as the conditions of zero transverse shear stresses on the upper and lower surfaces of plate. Also transverse flexibility and transverse normal strain and stress of core are considered. The effect of geometrical parameters of the sandwich plate are studied. Comparison of the present results with those of plate theories confirms the accuracy of the proposed model.

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