Query: Finite Element Stress Analysis of Thin Die Detachment Process

Candidate papers:

abstract: One of the major developments in high density electronic packaging assembly processes is the capability of handling very thin semiconductor devices. In order to achieve high production yield in the assembly processes and high reliability for the final packages, careful study on the handling method of very thin dice is therefore needed. In this article, we focus on the die detachment process of very thin dice in the die bonding process. Both 2D and 3D finite element models are built to simulate the die detachment process of a thin die, which is adhered to a plastic adhesive film. We report the stress distribution of the die when it is subjected to a displacement load by multiple push up pins.
author_names: Arthur C M Chong

Y M Cheung
title: Finite element stress analysis of thin die detachment process
venue: Fifth International Conference onElectronic Packaging Technology Proceedings, 2003. ICEPT2003.
year: 2003

abstract: Abstract The presented work focuses on numerical modelling and analysis of the forming process of a thin circular disc of negligible thickness, that is later subjected to vibration induced loading and unloading cycles (fatigue) during application. During the forming process, the material of the pre form (Mild Carbon Steel, AISI 1075) is shaped into the required profile of the disc, using a fast moving punch that impacts on a die underneath. The profile consists of a hole at the center of the disc and predefined surface gradations along the periphery. This punching process is followed by heat treatment to relax the residual stresses developed. This paper discusses the development of a detailed thermo mechanical coupled model using the finite element method, to simulate the different stages of the forming process; namely, the punching process, the instantaneous punch release and structural creep, and the subsequent heat treatment to induce stress relaxation. The numerical model is intended to predict the amount of residual stress and equivalent plastic strain that are developed in the disc at the end of each stage of the forming process. The stress concentration in the disc has serious implications on the subsequent cyclic loading and unloading application. The results obtained from standard tests indicate initiation and propagation of cracks in the disc during application. The intensity and occurrence of crack initiation have a direct connection to the maximum residual stress developed in the disc during the forming process. In addition, the heat treatment model is also intended to investigate the temperature distribution in the disc, during the heating and the subsequent cooling operations. The results of the finite element model are then validated with experimental measurements for each of the stages of the forming process. The finite element packages, Abaqus/Explicit and Abaqus/Standard, are used in conjunction for the aforesaid modeling
author_names: Rojin Mathews

Anoop Pillai A

Unnikrishnan Divakaran
title: Finite Element Modeling of a Thin Circular Disc Manufactured by Forming Process used in Cyclic Loading and Unloading Applications
year: 2020

abstract: The finite element model of thin wall taper workpiece in spining was established by software ANSYS10.0,its forming process on the base of explicit dynamics optimizer LS DYNA,the deformation and stress feature in the forming process was analyzed,the influence factors of stress and strain on the work piece forming quality were studied.The results show that the stress and strain nephogram indicates the respective features in the forming process,and provides the foundation for solving the problems in the forming process.The simulation can easily find the faults and reasons of break,flanging,fold and unstability etc in the spinning.The spinning stress surging and the excessive reducing rate of wall are the most important factors that result in break.By optimizing the process parameters such as reducing rate of wall,rotating speed and load,the taper work piece forming quality can be effectively controlled.The analyzing results can provide reliable theoretical basis for the spinning die's design and parameters' choice.
author_names: Wu Zhenting
title: Finite Element Analysis of Stress and Strain Field in Thin wall Taper Workpiece During Spinning Forming
year: 2011

abstract: Ti 6Al 4V is widely utilized to manufacture airframe component structures with curvature, because of its excellent strength to weight ratio, outstanding resistance to corrosion, and inherent thermal and electrical compatibility with carbon fiber composite. Hot stretch bending (HSB) is an effective technology to manufacture these kinds of structures. When comparing the thin walled extrusion with the thick walled one, however, it is more difficult to form. The reason is that the local temperature of extrusion decreases more because of the heat transfer between extrusion and die. In this study, the material properties of Ti 6Al 4V were measured experimentally, such as the tensile property within the temperatures from 873 to 1023 K and the strain rates from 0.0005 to 0.005 s 1, the stress relaxation behavior in a wide range of temperatures (773 973 K) and prestrains (0.7 10% as well as the heat transfer rule between Ti 6Al 4V (extrusion material) and asbestos cement (die material) under different pressures (8 25 MPa) The heat transfer coefficients (HTCs) were determined by an inverse analysis procedure, which was based on the comparison between measured and calculated temperature. Then, the coupled thermomechanical finite element (FE) model considering the effect of heat transfer was established. The influence of preheating temperature of die, initial temperature of extrusion, and dwell time on spring back was researched based on orthogonal array testing strategy (OATS) The optimized parameters were verified by process test. It was showed that the established FE model could be used to predict spring back within a relative deviation of 8.05%
author_names: Gui-qiang Guo

Dongsheng Li

Xiao-qiang Li

Tongsheng Deng

Shuo Wang
title: Finite element simulation and process optimization for hot stretch bending of Ti 6Al 4V thin walled extrusion
year: 2017

abstract: Wafers warp. It is important to minimize warpage in order to achieve optimal die yield and potentially prevent future device failure. Although the word warpage is widely used in the literature to represent wafer bow (convex or concave shape) in the real world wafers are often seen into warp into saddle shapes. This complicates the characterization of both the sources of and solutions to warpage, because (as will be discussed) Stoney's formula (relating intrinsic stress and curvature) does not apply for structures warped with compound curvature, and standard wafer warpage measurements are not designed to measure compound curvature. During thin film deposition, wafer warpage occurs due to the intrinsic stresses and the coefficient of thermal expansion (CTE) mismatch of the different thin films and the substrate. Unfortunately, whereas the introduction of the thermal stresses due to CTE mismatch into a finite element model is easily understood, the introduction of intrinsic stress is not. Further, although
author_names: Aditi Mallik

Roger Stout
title: Simulation of Process Stress Induced Warpage of Silicon Wafers Using ANSYS(r) Finite Element Analysis
year: 2010

abstract: Incremental sheet metal forming process is a new procedure that forms three dimensional parts of metal in a thin sheet. In particular, single point incremental forming of sheet metal is considered as a process that forms products without using complex dies and specific forming tool. Through this process, a cylindrical rotating punch with hemispherical end shape follows a predefined continuous or discontinuous trajectory to deform the sheet plastically. This fabrication method is known for its flexibility and the adaptation to complex geometrical shapes [6] In the present work, the single point incremental forming process (SPIF) has been investigated experimentally and numerically using 3D finite element analysis (FEA) Regarding concerns of the material, the sheets were produced from aluminum alloy. This study focuses on using numerical simulations as a tool to predict and control some mechanical and geometrical responses. In order to understand the effect choice of model constitutive laws, we intend to compare between two relationships of stress strain hardening behavior, implemented on ABAQUS software, with the experimental results. Based on the obtained findings, a comparison study was presented in this paper between experimental and numerical results. Different outputs responses were extracted such as global geometry (springback error, shape and final achieved section profiles) and thickness distribution. Therefore, the results obtained from the simulation were validated experimentally and good correlations are found, also the process strategies show good agreement with the experiments. Simultaneously, we conclude the most efficient hardening behavior of the material that insures the obtaining of results that are as close as possible to the experimental ones.
author_names: Asma Ben Khalfallah

Slim Ben Elechi

Riadh Bahloul
title: Experimental Investigation and Finite Element Modeling on Incremental Forming Process of Aluminum Sheet Alloys
year: 2019

abstract: In this study, a design guideline for the die cavity and die bearing length distribution is proposed during an extrusion process of an asymmetrical thin sheet, such as clips of cell phones. The plastic flow pattern of the billet inside the die cavity is analyzed using a commercial finite element package "DEFORM 3D" The Module of Die Stress Analysis in the finite element software "DEFORM 3D" is also used to simulate the stress, strain, and the displacement distributions of the die during extrusion of clips of cell phones. The extrusion load, the stress and strain distributions of the die, the temperature distribution, and thickness distribution of the extruded product are investigated. Furthermore, hot extrusion experiments using A6061 as the specimen are executed. The experimental results of temperature, thickness distribution of the product, extrusion force, etc, are compared with the analytical values to verify the validity of the proposed die design guideline.
author_names: Y M Hwang
title: Finite Element Analysis of Hot Aluminum Extrusion of Asymmetric Parts
year: 2015

abstract: Slacked multi chip package (MCP) has been an increasingly important approach for realizing high density 3D packaging. To accommodate multiple chips within a standard package height with adequate integrity and reliability puts stringent demands on wafer thinning technology, as well as on assembly process technology. In this work, internal stress distribution and package warpage in MCP originated from process thermal load have been systematically investigated as functions of all structure parameters by finite element analysis (FEA) and Taguchi design of experiments (DOE) It is found that top die is the easiest to crack under thermal stress. The maximum stress in this die can be effectively relieved by increasing its thickness and/or by decreasing the thickness of die attach underneath. Shear stress at each interface depends negatively on the corresponding die attach thickness, while top surface warpage can be controlled by mould compound thickness above top die.
author_names: Biao Liu

Mingxiang Wang

Tim Fai Lam
title: Finite element stress analysis of an multi chip package by Taguchi design of experiments for package component thicknesses
venue: Proceedings. 7th International Conference on Solid State and Integrated Circuits Technology, 2004.
year: 2004

abstract: The cold expanding diameter process was simulated by the software of DEFORM. The finite element model of tube and dies were built. The object position definition, the inter object setting, movement definition and simulation step were correctly set. The deformation, total velocity distribution and equivalent stress distribution were predicted. The numerical simulation results showed that the finite element analysis could exactly describe the plastic deformation and stress distribution during the forming process.
author_names: Wei Hua Kuang
title: Finite Element Analysis of Cold Expanding of Hollow Thin Wall Tube
year: 2011

abstract: In molding process, there is a step to release molded package blocks from the moulds by ejection pins. Silicon die crack failures might occur in some kind of thin small outline package (TSOP) in this mould release step. In this work, mould release process for a TSOP product is simulated by finite element method to clarify the mechanism of silicon die crack failures. Our analysis demonstrates that some adhesion area by organic contamination on mould inner surface, during mould release step, may impede package block to be released smoothly from the mould, leading to locally built internal stress within silicon and causing die crack failures. Die crack risks with adhesion area in different size, shape and position are compared and high risk conditions are defined. Die crack failure can be reduced in packages using high elastic molding compound (MC)
author_names: Zhenyu Yang

Mingxiang Wang

Huaping Xu
title: Finite Element Analysis of TSOP Silicon Die Crack Issue during Molding Process
venue: 2006 7th International Conference on Electronic Packaging Technology
year: 2006