Wirebond Deformation During Molding of IC Packages

1995 ◽  
Vol 117 (1) ◽  
pp. 14-19 ◽  
Author(s):  
A. A. O. Tay ◽  
K. S. Yeo ◽  
J. H. Wu ◽  
T. B. Lim
Keyword(s):  
Gold Wire ◽  
Creeping Flow ◽  
The Finite Element Method ◽  
Melt Flow ◽  
Hardening Material ◽  
Transfer Molding ◽  
Viscous Forces ◽  
Parametric Studies ◽  
Short Circuits ◽  
Very High

During the transfer molding of IC packages, wirebonds are deformed by the action of flow-induced viscous forces acting along them. Excessive deformation of wirebonds could give rise to short circuits and bond pull-outs. In this paper, the deformation of gold wirebonds during transfer molding of IC packages is studied using the finite element method. Hitherto, only elastic deformation of wirebonds has been considered. In this paper, a more realistic elasto-plastic large-deflection model is employed. The gold wire is assumed to be made of a bilinear strain hardening material. It is shown that plastic deformation in the wirebond can occur even if the melt flowrate is not very high. However, wirebond deflection may still be within acceptable limits even though certain portions of the wirebond have yielded plastically. The deformation of parabolic wirebonds under the action of melt flow, both normal and parallel to the plane of the wirebond, is also studied. The melt flow within the cavity is simulated assuming creeping flow. Parametric studies of the effects of wirebond dimensions, namely bond height, span and wire diameter, on wirebond deformation are also carried out.

Simulation of Mold Filling for Non-Newtonian Fluids - Part 2

2006 ◽  
Vol 3 (2) ◽  
pp. 52-60
Author(s):  
Venkatesh M. Kulkarni ◽  
Chu Wee Liang ◽  
C.W. Tan ◽  
P.A. Aswatha Narayana ◽  
K.N. Seetharamu
Keyword(s):  
Stokes Equations ◽  
Navier Stokes ◽  
The Finite Element Method ◽  
Molding Process ◽  
Algebraic Form ◽  
Design Guideline ◽  
Navier Stokes Equations ◽  
Transfer Molding ◽  
Encapsulation Process ◽  
Parametric Studies

This paper deals with the flow in the resin transfer molding process commonly used for IC chip encapsulation in the electronic packaging industry. A solution algorithm is presented for modeling the flow of a non-Newtonian fluid obeying a Power-Law model and the algorithm is used to conduct parametric studies in transfer molding. The flow model uses the Hele-Shaw approximation to solve the Navier-Stokes Equations and a pseudo-concentration algorithm for tracking the interface between the resin and the air. The Finite Element Method is employed to reduce the governing partial differential equations to algebraic form. The model is used to study the flow from the transfer ram into the cavity for different dimensions of transfer molding tools. Parametric studies are carried out to obtain balanced filling for transfer molding configuration. Parametric studies could provide a design guideline to optimize the encapsulation process prior to the setting up of an actual manufacturing set.

Double Overhung Disk and Parameter Effect on Rotordynamic Synchronous Instability—Morton Effect—Part II: Occurrence and Prevention

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Xiaomeng Tong ◽  
Alan Palazzolo
Keyword(s):  
Transient Analysis ◽  
Operating Parameters ◽  
Flow Ratio ◽  
The Finite Element Method ◽  
Oil Viscosity ◽  
Testing Conditions ◽  
Bending Mode ◽  
Morton Effect ◽  
Nonlinear Transient ◽  
Parametric Studies

This paper performs the parametric studies corresponding with the theoretical Morton effect (ME) model explained in Part I of this paper, where the fully nonlinear transient analysis based on the finite element method is introduced. Operating parameters, such as oil supply temperature, bearing clearance, oil viscosity, etc., are perturbed from the testing conditions to investigate the shifting of critical speeds and ME instability onset speed (IOS). The ME is significantly affected by the rotor bending mode with large overhung deflections, and operating parameters should be adjusted to increase the separation margin between the operating speed and the corresponding critical speed for ME mitigation. Reducing the carryover flow ratio and using the asymmetric bearing pivot offset are capable to suppress the ME by reducing both the average and differential journal temperature. The heat barrier sleeve with air or ceramic isolation is designed to prevent the heat flux into the journal and can successfully mitigate the ME based on the simulations.

Stokes flow past bubbles and drops partially coated with thin films. Part 2. Thin films with internal circulation – a perturbation solution

1983 ◽  
Vol 132 ◽  
pp. 295-318 ◽  
Author(s):  
Robert E. Johnson ◽  
S. S. Sadhal
Keyword(s):  
Thin Films ◽  
Fluid Layer ◽  
Cell Structure ◽  
Creeping Flow ◽  
Immiscible Fluid ◽  
Fluid Viscosity ◽  
Perturbation Scheme ◽  
Bulk Fluid ◽  
Viscous Forces ◽  
Surface Tension Forces

In the present study we examine the steady axisymmetric creeping flow due to the motion of a liquid drop or a bubble which is partially covered by a thin immiscible fluid layer or film. The analysis is based on the assumption that surface-tension forces are large compared with viscous forces which deform the drop, and that the circulation in the film is weak. The latter assumption is satisfied provided that the film-fluid viscosity is not too small. A perturbation scheme based on the thinness of the fluid layer is used to construct the solution.One of the principal results is an expression for the drag force on the complex drop. We also find that the extent to which the drop or bubble is covered the film has a maximum value depending on the magnitude of the driving force on the film. In addition, we find the rather interesting result that when the ratio of the primary drop viscosity and bulk fluid viscosity is greater than ½, the circulation within the film may have a double-cell structure.

Development of Direct Carbonate Fuel Cell Systems for Achieving Ultrahigh Efficiency

2011 ◽  
Vol 8 (3) ◽  
Author(s):  
Hossein Ghezel-Ayagh ◽  
Joseph McInerney ◽  
Ramki Venkataraman ◽  
Mohammad Farooque ◽  
Robert Sanderson
Keyword(s):  
Fuel Cell ◽  
System Simulation ◽  
Cfd Modeling ◽  
Fuel Cell Stack ◽  
In Series ◽  
Parametric Studies ◽  
Second Tier ◽  
System Configurations ◽  
Carbonate Fuel Cell ◽  
Very High

FuelCell Energy, Inc. (FCE) has developed products based on its Direct FuelCell® (DFC®) technology with efficiencies near 50% based on lower heating values of natural gas. DFC is an internally reformed molten carbonate fuel cell, which operates in the 550–700°C range. The combination of the internal reforming of methane and atmospheric pressure and moderately high temperature of operation has resulted in very simple power plant system configurations. Recently, FCE has developed system concepts to further increase the net electric efficiency to beyond 60% efficiency in sub-MW and MW class power plants. One of these system concepts is the arrangement of the fuel cell stacks in series for very high utilization of fuel in the stacks. Although, in principle, the concept of fuel cell stacks in series is very simple, the implementation of the concept in the actual hardware poses challenges requiring innovative solutions. These challenges include concerns with thermomechanical issues, flow and utilization patterns within the fuel cell stacks, and management of the pressure balance between the anode and the cathode. To address these issues, various analytical tools, including system-level modeling and simulation and computational fluid dynamics (CFD), were utilized. FCE has developed a comprehensive fuel cell stack operation simulation model including hydrodynamics, kinetics, electrochemical, and heat transfer mechanisms to investigate and optimize the design for performance as well as endurance. Various system configurations were developed, which included methods for fueling the second tier stacks in the series. System simulation studies using first principle mass and energy conversation laws were performed. Parametric studies were completed. Subsequent to the system modeling results, the fuel cell stack operations were analyzed using the comprehensive stack simulation model. The CFD modeling of the fuel cell stacks was performed in support of the system simulation parametric studies. The results of the CFD modeling provided insight to the thermal and flow profiles of both first and second tier stacks in series. The net outcome of the investigation was the design of the system, which met the goals of ultrahigh efficiency and yet complied with the thermomechanical requirements of the fuel cell stack components. In this paper, FCE will describe various system options for the very high efficiency systems, the issues related to the design, and the practical solutions to overcome the issues.

scholarly journals Finite Element Modelling of Oxygen Diffusion and Segregation at Interfaces in Ag-MgO Composites: Parametric Studies

2008 ◽  
Vol 273-276 ◽  
pp. 461-466
Author(s):  
Andreas Öchsner ◽  
Irina V. Belova ◽  
Graeme E. Murch
Keyword(s):  
Finite Element ◽  
Finite Element Modelling ◽  
Atomic Oxygen ◽  
Model System ◽  
Point Of View ◽  
The Finite Element Method ◽  
Oxide Interfaces ◽  
Bulk Properties ◽  
Metal Ceramic ◽  
Parametric Studies

The presence of atomic oxygen at internal metal-ceramic oxide interfaces signifi- cantly affects the physical properties of the interfaces which in turn affects the bulk properties of the material. This problem is addressed for the model system Ag-MgO from a phenomenolog- ical point of view using the finite element method. The performed parametric studies investigate the influence of different kinetic parameters of the diffusion-segregation system.

scholarly journals Axial creeping flow in the gap between a rigid cylinder and a concentric elastic tube

2016 ◽  
Vol 806 ◽  
pp. 580-602 ◽  
Author(s):  
S. B. Elbaz ◽  
A. D. Gat
Keyword(s):  
Fluid Layer ◽  
Elastic Shell ◽  
Gravity Current ◽  
Travelling Wave ◽  
Elastic Tube ◽  
Creeping Flow ◽  
Shear Stresses ◽  
Length Scales ◽  
Rigid Cylinder ◽  
Viscous Forces

We examine transient axial creeping flow in the annular gap between a rigid cylinder and a concentric elastic tube. The gap is initially filled with a thin fluid layer. We employ an elastic shell model and the lubrication approximation to obtain governing equations for the elastohydrodynamic interaction. At long axial length scales viscous forces are balanced by elastic tension, while at shorter length scales the viscous–elastic balance is achieved by means of an interplay between elastic bending, tension and shear stresses. Based on a viscous gravity current analogy in the tensile–viscous regime, we devise propagation laws for displacement flows which are induced by a variety of boundary conditions and examine different limits of the prewetting thickness. Next we focus on the moving elastohydrodynamic contact line at the edge of a penetrating film. A uniform matched asymptotic solution connecting the interior tension-based region with a boundary layer region near the propagation front is presented. Finally, a constructive example is shown in which isolated moving deformation patterns are created and superimposed to form a travelling wave displacement field. The presented interaction between viscosity and elasticity may be applied to fields such as soft robotics and micro-scale or larger swimmers by allowing for the time-dependent control of an axisymmetric compliant boundary.

Analysis of Toroidal Shells Using the Differential Quadrature Method

2003 ◽  
Vol 03 (02) ◽  
pp. 215-226 ◽  
Author(s):  
D. Redekop ◽  
T. Muhammad
Keyword(s):  
Finite Element ◽  
Differential Quadrature Method ◽  
Differential Quadrature ◽  
Quadrature Method ◽  
The Finite Element Method ◽  
Complementary Method ◽  
Finite Element Calculations ◽  
Parametric Studies ◽  
New Applications ◽  
Toroidal Shells

In new applications of toroidal shells it is often necessary to solve problems of statics, response, vibration, and buckling. While the finite element method can serve as the main means of analysis it is desirable to have available a second, complementary, method that can be used for verification, parametric studies, and specialized analyses. In this paper the use of the new differential quadrature method in such a complimentary role is investigated. Problems involving the statics, response, vibration, and buckling of toroidal shells are analyzed. Numerical results obtained are compared with finite element calculations. Finally conclusions are drawn concerning the agreement between the methods, and the usefulness of the new method for specialized studies.

scholarly journals Analysis of Bubble Growth in Supercritical CO2 Extrusion Foaming Polyethylene Terephthalate Process Based on Dynamic Flow Simulation

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2799
Author(s):  
Shun Yao ◽  
Yichong Chen ◽  
Yijie Ling ◽  
Dongdong Hu ◽  
Zhenhao Xi ◽  
...  
Keyword(s):  
Polyethylene Terephthalate ◽  
Bubble Growth ◽  
Supercritical Co2 ◽  
Flow Simulation ◽  
The Finite Element Method ◽  
Melt Flow ◽  
Dynamic Flow ◽  
Foaming Process ◽  
Dynamic Rheological Properties ◽  
Extrusion Foaming

Bubble growth in the polymer extrusion foaming process occurs under a dynamic melt flow. For non-Newtonian fluids, this work successfully coupled the dynamic melt flow simulation with the bubble growth model to realize bubble growth predictions in an extrusion flow. The initial thermophysical properties and dynamic rheological property distribution at the cross section of the die exit were calculated based on the finite element method. It was found that dynamic rheological properties provided a necessary solution for predicting bubble growth during the supercritical CO2 polyethylene terephthalate (PET) extrusion foaming process. The introduction of initial melt stress could effectively inhibit the rapid growth of bubbles and reduce the stable size of bubbles. However, the initial melt stress was ignored in previous work involving bubble growth predictions because it was not available. The simulation results based on the above theoretical model were consistent with the evolution trends of cell morphology and agreed well with the actual experimental results.

scholarly journals Modeling of Harmonic Wave Propagation Through a Metasurface with Helmholtz Resonator Shaped Cells

2021 ◽  
Vol 2117 (1) ◽  
pp. 012002
Author(s):  
A Y Ismail ◽  
B Y Koo
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Wave Propagation ◽  
Harmonic Wave ◽  
Helmholtz Resonator ◽  
Numerical Results ◽  
Shape Design ◽  
The Finite Element Method ◽  
Parametric Studies ◽  
Engineering Practices

Abstract Harmonic wave propagation through a novel metasurface design is presented in this paper. The metasurface is formed by using the Helmholtz resonator as the cells shape design since such resonator has uniqueness and advantageous performances. The study is conducted both numerically using the finite element method and experimentally using specific measurements to validate the numerical results. Parametric studies of the selected variables are also conducted to obtain broader information on the performance. From the result, it is found that the new proposed metasurface design has the potential to be implemented in future engineering practices.

Numerical analysis and experimental verification of the radial growth of a turbocharger centrifugal compressor impeller

1997 ◽  
Vol 32 (2) ◽  
pp. 119-128 ◽  
Author(s):  
D A Subramani ◽  
V Ramamurti ◽  
K Sridhara
Keyword(s):  
Finite Element Method ◽  
Centrifugal Compressor ◽  
Experimental Verification ◽  
Radial Growth ◽  
Cyclic Symmetry ◽  
The Finite Element Method ◽  
Compressor Impeller ◽  
Novel Method ◽  
Very High ◽  
State Stress

Steady state stress analysis was carried out on a typical automotive turbocharger centrifugal compressor impeller using the finite element method and the concept of cyclic symmetry. Since the rotational speed of the impeller is very high and the size of the impeller is quite small, experimental verification of the stresses is extremely difficult. A novel method of measuring the radial growth of the impeller tip has been presented and a suitable instrumentation was designed and developed. This paper describes the numerical and experimental work carried out on a centrifugal compressor impeller

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