Warpage Simulation During Fan-Out Wafer-Level Packaging Process with Uncertainty of Material Properties

2021 ◽  
Vol 21 (5) ◽  
pp. 2987-2991
Author(s):  
Geumtaek Kim ◽  
Daeil Kwon
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Material Properties ◽  
Coefficient Of Thermal Expansion ◽  
Input Output ◽  
Wafer Level ◽  
High Input ◽  
Element Analysis ◽  
Packaging Process ◽  
Wafer Level Packaging

Along with the reduction in semiconductor chip size and enhanced performance of electronic devices, high input/output density is a desired factor in the electronics industry. To satisfy the high input/output density, fan-out wafer-level packaging has attracted significant attention. While fan-out wafer-level packaging has several advantages, such as lower thickness and better thermal resistance, warpage is one of the major challenges of the fan-out wafer-level packaging process to be minimized. There have been many studies investigating the effects of material properties and package design on warpage using finite element analysis. Current warpage simulations using finite element analysis have been routinely conducted with deterministic input parameters, although the parameter values are uncertain from the manufacturing point of view. This assumption may lead to a gap between the simulation and the field results. This paper presents an uncertainty analysis of wafer warpage in fan-out wafer-level packaging by using finite element analysis. Coefficient of thermal expansion of silicon is considered as a parameter with uncertainty. The warpage and the von Mises stress are calculated and compared with and without uncertainty.

Reduction of Thermal Stress - Part III: UBM and Passivation Thickness Optimization

2017 ◽  
Vol 2017 (1) ◽  
pp. 000694-000698
Author(s):  
Raj Sekar Sethu ◽  
Salil Hari Kulkarni ◽  
How Ung Ha ◽  
Kok Heng Soon
Keyword(s):  
Finite Element Analysis ◽  
Solder Ball ◽  
Coefficient Of Thermal Expansion ◽  
Thickness Optimization ◽  
Wafer Level ◽  
Element Analysis ◽  
Wafer Level Packaging ◽  
Two Factors ◽  
Process Factors ◽  
Significant Factors

Abstract Integration of Back End Of Line (BEOL) CMOS technologies with Wafer Level Packaging (WLP) is challenging, as mismatch of Coefficient of Thermal Expansion (CTE) between materials can result in thermo-mechanical induced cracking. This is especially true during reflow cooling of wafers after the solder ball attach process. Factors that contribute towards cracking can be from both the BEOL as well the WLP process steps. Finite Element Analysis (FEA) of such designs can help identify possible root causes early in the design process and i.e. before actual fabrication. This would help save valuable prototyping & testing costs. In Part III of this series of FEA studies, two factors i.e. silicon nitride thickness (from the BEOL process), and the Under Bump Metalization (UBM) thickness (from the WLP process) were identified as significant factors in changing the maximum first principal stress levels in the passivation layer.

PROCESS OPTIMIZATION AND SENSITIVITY INVESTIGATION IN LASER FORMING WITH FINITE ELEMENT ANALYSIS

2007 ◽  
Vol 04 (04) ◽  
pp. 653-670 ◽  
Author(s):  
H. C. JUNG ◽  
S. KRUMDIECK
Keyword(s):  
Thermal Conductivity ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Process Optimization ◽  
Material Properties ◽  
Coefficient Of Thermal Expansion ◽  
Laser Forming ◽  
Bend Angle ◽  
Forming Process ◽  
Element Analysis

Laser forming is a flexible sheet metal manufacturing technique capable of producing various shapes, without hard tools and external forces, by irradiation across the surface of the metal piece. A three-dimensional thermal-elasto-plastic (TEP) finite element model for a straight line laser forming process has been developed during the course of this study, which simulates bend angles and temperature distributions. Laser forming process optimization and material sensitivity are investigated. In order to seek the optimal process conditions to generate a desired bend angle in the multi-scan laser bending process, an optimization algorithm based on the approximation of objective function and state variables is integrated into the numerical model. An optimal set of process parameters such as laser power, scan speed, beam diameter and the number of scans are obtained with optimization procedure. In order to assess process sensitivity to material roperties, associations between bend angle and material properties are statistically determined using the Pearson product-moment correlation coefficient via Monte Carlo simulations, for which a large number of the finite element simulations are carried out. The material properties of interest include the coefficient of thermal expansion, thermal conductivity, specific heat, modulus of elasticity, and Poisson's ratio. Results show that the process optimization coupled with finite element analysis can be used to determine processing parameters, and that the material properties of primary importance are the coefficient of thermal expansion, thermal conductivity and specific heat.

Finite Element Analysis of Functionally Graded Thick-Cylinders Subjected to Mechanical and Thermal Loads

2012 ◽  
Author(s):  
Jasem A. Ahmed ◽  
M. A. Wahab
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Material Properties ◽  
Radial Direction ◽  
Coefficient Of Thermal Expansion ◽  
Stress Component ◽  
Pressure Vessels ◽  
Functionally Graded ◽  
Design Parameters ◽  
Element Analysis

Functionally graded materials (FGM) are used to design structures used in high temperature environment. Hybrid pressure vessels can be designed from FGMs to incorporate improved strength, weight reduction, thermal properties, impact resistance etc. Progressive research in this area will lead to the determination of optimum design parameters and provide insight in developing manufacturing techniques of full-scale hybrid pressure vessels and experimental validation. In future, an accurate damage model will help in planning component examinations in a selective manner in order to provide useful information about material condition and predict the remaining life of the structure. A functionally graded thick-walled cylindrical vessel with varying material properties in the radial direction is considered. The cylinder is assumed to be made of one phase spatially dispersed in a matrix of another. Volume fractions of the phases are assumed to vary along the radial direction according to power laws. The gradation is represented by dividing the radial domain into finite sub-domains. The effective material properties such as modulus of elasticity, Poisson’s ratio, thermal conductivity and coefficient of thermal expansion are estimated using Mori-Tanaka [1], Hashin–Shtrikman [2], Hatta-Taya [3] and Rosen-Hashin [4] relations. The hollow cylinder is subjected to axisymmetric mechanical and thermal loadings. Finite Element Analysis is performed using a commercial package, ANSYS, to obtain temperature and stress component distribution along the thickness of the cylinder. Results are presented graphically to show the effect of internal pressure, temperature change, and gradient variation of material properties on stress components throughout the thickness.

scholarly journals On the Design of a Biodegradable POC-HA Polymeric Cardiovascular Stent

2012 ◽  
Author(s):  
Joonas Ponkala ◽  
Mohsin Rizwan ◽  
Panos S. Shiakolas
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Material Properties ◽  
Three Dimensional ◽  
Polymeric Composite ◽  
Coronary Stent ◽  
Element Analysis ◽  
Material Models ◽  
Solid Models ◽  
Biodegradable Stents

The current state of the art in coronary stent technology, tubular structures used to keep the lumen open, is mainly populated by metallic stents coated with certain drugs to increase biocompatibility, even though experimental biodegradable stents have appeared in the horizon. Biodegradable polymeric stent design necessitates accurate characterization of time dependent polymer material properties and mechanical behavior for analysis and optimization. This manuscript presents the process for evaluating material properties for biodegradable biocompatible polymeric composite poly(diol citrate) hydroxyapatite (POC-HA), approaches for identifying material models and three dimensional solid models for finite element analysis and fabrication of a stent. The developed material models were utilized in a nonlinear finite element analysis to evaluate the suitability of the POC-HA material for coronary stent application. In addition, the advantages of using femtosecond laser machining to fabricate the POC-HA stent are discussed showing a machined stent. The methodology presented with additional steps can be applied in the development of a biocompatible and biodegradable polymeric stents.

scholarly journals Investigation on Die Crack in a Stacked Die Package Using Finite Element Analysis

2021 ◽  
pp. 83-91
Author(s):  
Jefferson Talledo
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Coefficient Of Thermal Expansion ◽  
Crack Problem ◽  
Element Analysis ◽  
Robust Solution ◽  
Die Attach ◽  
Die Stress ◽  
Cte Mismatch ◽  
Semiconductor Packages

Die crack is one of the problems in stacked die semiconductor packages. As silicon dies become thinner in such packages due to miniaturization requirement, the tendency to have die crack increases. This study presents the investigation done on a die crack issue in a stacked die package using finite element analysis (FEA). The die stress induced during the package assembly processes from die attach to package strip reflow was analyzed and compared with the actual die crack failure in terms of the location of maximum die stress at unit level as well as strip level. Stresses in the die due to coefficient of thermal expansion (CTE) mismatch of the package component materials and mechanical bending of the package in strip format were taken into consideration. Comparison of the die stress with actual die crack pointed to strip bending as the cause of the problem and not CTE mismatch. It was found that the die crack was not due to the thermal processes involved during package assembly. This study showed that analyzing die stress using FEA could help identify the root cause of a die crack problem during the stacked die package assembly and manufacturing as crack occurs at locations of maximum stress. The die crack mechanism can also be understood through FEA simulation and such understanding is very important in coming up with robust solution.

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