Effect of Material Properties and Thickness of Die Attach on Delamination of Die Attach/Die Paddle Interface in Electronic Package

2010 ◽  
Author(s):  
Chia-Lung Chang ◽  
Po-Hsien Li
Keyword(s):  
Material Properties ◽  
Coefficient Of Thermal Expansion ◽  
Damage Parameter ◽  
Stress And Strain ◽  
Thermal Expansion Mismatch ◽  
The Finite Element Method ◽  
Electronic Package ◽  
Die Attach ◽  
Encapsulation Process ◽  
Die Bonding

The electronic package is a multi-layered structure that is consisted of several materials. Under the temperature loadings, the interfacial stresses between layered components are generated due to the CTE (coefficient of thermal expansion) mismatch between different materials. In die bonding process, the void or defect might exist at the die attach/die paddle interface. The void cause further delamination on the interface during the encapsulation process. In this study, the finite element method is used to construct the model of electronic package with a void on the die attach/die paddle interface. The energy release rate based on J integration, which is calculated by the stress and strain around the tip of crack, is used as a damage parameter to predict the tendency of further delamination during encapsulation. Effect of material properties (Young’s modulus and CTE) and die attach thickness on delamination of die attach/die paddle interface in package during encapsulation is studied.

A General Solution for the Elastoplastic Thermal Stresses in a Strain-Hardening Plate With Arbitrary Material Properties

1962 ◽  
Vol 29 (1) ◽  
pp. 151-158 ◽  
Author(s):  
A. Mendelson ◽  
S. W. Spero
Keyword(s):  
Thermal Expansion ◽  
General Solution ◽  
Strain Hardening ◽  
Material Properties ◽  
Thermal Stresses ◽  
Coefficient Of Thermal Expansion ◽  
Stress And Strain ◽  
Linear Strain ◽  
Hardening Material ◽  
General Method

A general method is presented for obtaining the elastoplastic stress and strain distributions in a thermally stressed plate of a strain-hardening material with temperature-varying modulus, yield point, and coefficient of thermal expansion. It is shown that for linear strain-hardening the solution can often be obtained in closed form. It is indicated that the error due to neglecting strain-hardening may sometimes be appreciable. The assumption that the total strain remains the same as that computed elastically (strain invariance) often leads to smaller errors than the neglect of strain-hardening.

Simulation of Effect of Solder Balls Layout on Warpage and Interfacial Stresses of FBGA

2012 ◽  
Vol 165 ◽  
pp. 334-338
Author(s):  
Chia Lung Chang ◽  
Li Chung Chen ◽  
Po Hsien Li
Keyword(s):  
Coefficient Of Thermal Expansion ◽  
The Finite Element Method ◽  
Interfacial Stresses ◽  
Sequential Processing ◽  
Die Attach ◽  
Fine Pitch ◽  
Processing Step ◽  
Solder Balls ◽  
Simulation Results ◽  
Processing Steps

The finite element method is used to construct the sequential processing model of the package. The model is used to simulate the warpage and interfacial stresses of FBGA (Fine-pitch Ball Grid Array) package due to the coefficient of thermal expansion mismatch between layered materials of package during assembly processes. The processing model uses the function of element birth and death to simulate the processing step of package model, considering the sequentially accumulated warpage and stresses during the processing steps. The induced package stresses can cause the delamination between die/die attach interface. In order to verify the simulation results, the simulated package warpage of a standard package is compared with the measurement of package warpage of the package. In this study, the effect of solder balls layout on the warpage and interfacial stresses at die/die attach interface is discussed by simulation results.

Investigation of Transfer Mold Process Effects on Semiconductor Package Warpage

2009 ◽  
Author(s):  
Jason M. Brand ◽  
Myung J. Yim ◽  
Ravi Kumar
Keyword(s):  
Solder Joint ◽  
Material Property ◽  
Material Properties ◽  
Coefficient Of Thermal Expansion ◽  
Filler Concentration ◽  
Packaging System ◽  
Property Variation ◽  
Molding Compound ◽  
Fea Model ◽  
Die Attach

In recent years, Package on Package (PoP) is increasingly used for high density package solutions. Generally the top package is a stacked memory packaging system connected to a bottom logic packaging system via solder joint: this is representative of PoP configurations. To guarantee the assembly yield and reliability of the solder joint between the top package and bottom package, mechanical compliance between these two packages is crucial during package stacking. Henceforth package warpage needs to be understood and controlled to meet the assembly yield targets. The complexity of the package configuration increases by thinner package thickness, higher number of stacking dies and large package size. Controlling the warpage within the target requirement is very challenging, especially when the material behaviors of substrate, die, molding compound and die attach film are different and also changing as a function of temperature. Certainly, the material properties of key components in top PoP package plays a crucial role in warpage performance. Among various material properties, the chemical cure shrinkage, coefficient of thermal expansion and storage modulus for the molding compounds are determining factors on the temperature dependant warpage control of top PoP package. Warpage variation still exists within parts processed at the same time mainly due to slight material property variation. In this paper, the cause of the warpage variation is investigated. The main cause was found to be filler migration effect in narrow gaps with in the stacked die package during the mold process, which resulted in different filler concentration and distribution, and finally different local molding compound material property among the package unit location in the substrate strip. The findings indicate that mold pressure is not a major modulator of warpage, while filler distribution can dramatically alter the warpage behavior. FEA model results and warpage data are presented to validate the filler migration phenomena and warpage behavior impact. The findings and results provide some clues and design/process guideline for warpage control in Top PoP package, which influence the PoP assembly yield and reliability.

Epoxy Die Attach Combined With Face-Up Die Bonding for Improved XYZ Placement Accuracy

2021 ◽  
Author(s):  
Tadeh Avanessian ◽  
Jim Clatterbaugh ◽  
Robin L. Zinsmaster ◽  
Leyla Hashemi
Keyword(s):  
Flip Chip ◽  
Coefficient Of Thermal Expansion ◽  
Test Results ◽  
Microelectronics Packaging ◽  
Bond Failure ◽  
Die Attach ◽  
Before And After ◽  
Placement Accuracy ◽  
Die Bonding ◽  
Heated Stage

Abstract Epoxy die attach is widely used in microcircuit assembly and enjoys advantages such as ease of deposition, fast curing, reworkability, and non-toxicity. These qualities also make it suitable for automated mass production. However, this method falls short when high placement accuracy is desired as the die can shift on uncured epoxy leading to die displacement from its original location. Gold to gold face-up bonding is another method utilized in microelectronics packaging given its proven bonding reliability and high placement accuracy for small devices. Nevertheless, it is difficult to achieve a reliable bond using this method for relatively larger devices. The nonplanarity of the bonding collet or the variation in the height of the gold bumps results in a tilted die attach and/or a weak bond between the die and the substrate. Moreover, CTE (Coefficient of Thermal Expansion) mismatch between the die, the gold bumps, and/or the substrate leads to bond failure due to temperature fatigue. This paper discusses a hybrid method to take advantage of the strengths of both methods mentioned above, culminating in a reliable process with high XYZ placement accuracy. To apply this method, epoxy is first dispensed on a gold-plated substrate. Using a flip chip machine, samples with plated gold bumps on their ground side are then placed on the substrate. The gold bumps are mainly used as targets and stand-offs to improve the placement accuracy and to control epoxy glue-line thickness. The force applied on the die, the time the force is applied, and the substrate temperature are controlled for optimum die attach. Moreover, along with the force applied by the vacuum tip, epoxy is partially cured on the flip chip machine heated stage before it is moved to an oven to complete the cure process. Die shear test results before and after temperature conditioning are compared with standard epoxy die attach and gold to gold face-up bonding for identical samples and the advantages are discussed.

Temperature Dependence of the Mechanical Properties of GaAs Wafers

1991 ◽  
Vol 113 (4) ◽  
pp. 331-336 ◽  
Author(s):  
Jun Ming Hu ◽  
Michael Pecht
Keyword(s):  
Mechanical Properties ◽  
Material Properties ◽  
Coefficient Of Thermal Expansion ◽  
Critical Value ◽  
Modulus Of Rupture ◽  
Gaas Wafer ◽  
Photovoltaic Conversion Efficiency ◽  
Die Attach ◽  
Different Temperatures ◽  
Fracture Assessment

GaAs is known to have superior electronic properties and greater photovoltaic conversion efficiency compared to elemental semiconductors such as silicon and germaniumn. Mechanical properties of GaAs at different temperatures are now necessary to incorporate into the design models for the GaAs die attach and substrate architecture for microelectronic packages. These properties are also required to aid in defining reliability and screening specifications. This paper presents the experiment results on various material properties of GaAs wafer over the temperature range of − 75°C to 200°C. Material properties determined from testing include the modulus of elasticity, the modulus of rupture, the critical value of stress intensity factor, and the coefficient of thermal expansion. The importance of fracture assessment in semiconductor devices is also discussed.

Effects of Material Properties and Thickness of Die Attach on Warpage and Stresses of TSOP

2011 ◽  
Vol 264-265 ◽  
pp. 542-547
Author(s):  
Chia Lung Chang ◽  
P.Y. Chen ◽  
M.H. Huang
Keyword(s):  
Nonlinear Model ◽  
Material Properties ◽  
Residual Deformation ◽  
Primary Factor ◽  
Chemical Shrinkage ◽  
Process Step ◽  
Electronic Package ◽  
Molding Compound ◽  
Die Attach ◽  
Plastic Package

The assembly of plastic electronic package requires a sequence of process steps. Every process step induces thermal residual deformation and stresses on the assembled components, which cause mechanical effects on the subsequent process step. Processing model with considering the effect of chemical shrinkage on molding compound is built to simulate the package warpage and stresses in assembly. The processing model, a nonlinear model with element birth and death used to activate and deactivate the processing materials, can more realistically simulate a series of assembly processes in a plastic package. The stresses in package components are primary factor for the damage of package. The induced package stresses can cause the delamination between die/die attach interface or die attach/die pad interface. In this study, effects of material properties as well thickness of die attach on warpage and stresses of TSOP (Thin Small Outline Package) during assembly are discussed.

Analysis of Two Electrical Failures Caused by Die Attach of Exposed Pad Package

2014 ◽  
Author(s):  
Jinglong Li ◽  
Motohiko Masuda ◽  
Yi Che ◽  
Miao Wu
Keyword(s):  
Bonding Process ◽  
Die Attach ◽  
Die Bonding ◽  
Generic Analysis

Abstract Die attach is well known in die bonding process. Its electrical character is simple. But some failures caused by die attach are not so simple. And it is not proper to analyze by a generic analysis flow. The analysis of two failures caused by die attach are presented in this paper.

FEMLIB: An Object-Oriented Framework for Optimization and Simulation

1995 ◽  
Author(s):  
Michael M. Tiller ◽  
Jonathan A. Dantzig
Keyword(s):  
Material Properties ◽  
Object Oriented ◽  
The Finite Element Method ◽  
Simulation And Optimization ◽  
Gradient Based ◽  
Level Problem ◽  
Simulation Results ◽  
Optimization And Simulation ◽  
High Level ◽  
Simulation Parameters

Abstract In this paper we discuss the design of an object-oriented framework for simulation and optimization. Although oriented around high-level problem solving, the framework defines several classes of problems and includes concrete implementations of common algorithms for solving these problems. Simulations are run by combining these algorithms, as needed, for a particular problem. Included in this framework is the capability to compute the sensitivity of simulation results to the different simulation parameters (e.g. material properties, boundary conditions, etc). This sensitivity information is valuable in performing optimization because it allows the use of gradient-based optimization algorithms. Also included in the system are many useful abstractions and implementations related to the finite element method.

scholarly journals Infarcted Left Ventricles Have Stiffer Material Properties and Lower Stiffness Variation: Three-Dimensional Echo-Based Modeling to Quantify In Vivo Ventricle Material Properties

2015 ◽  
Vol 137 (8) ◽  
Author(s):  
Longling Fan ◽  
Jing Yao ◽  
Chun Yang ◽  
Dalin Tang ◽  
Di Xu
Keyword(s):  
Wall Thickness ◽  
Material Properties ◽  
Strain Curve ◽  
Stress And Strain ◽  
Stress Strain ◽  
Material Stiffness ◽  
The Mean ◽  
Lv Volume ◽  
Parameter Values

Methods to quantify ventricle material properties noninvasively using in vivo data are of great important in clinical applications. An ultrasound echo-based computational modeling approach was proposed to quantify left ventricle (LV) material properties, curvature, and stress/strain conditions and find differences between normal LV and LV with infarct. Echo image data were acquired from five patients with myocardial infarction (I-Group) and five healthy volunteers as control (H-Group). Finite element models were constructed to obtain ventricle stress and strain conditions. Material stiffening and softening were used to model ventricle active contraction and relaxation. Systolic and diastolic material parameter values were obtained by adjusting the models to match echo volume data. Young's modulus (YM) value was obtained for each material stress–strain curve for easy comparison. LV wall thickness, circumferential and longitudinal curvatures (C- and L-curvature), material parameter values, and stress/strain values were recorded for analysis. Using the mean value of H-Group as the base value, at end-diastole, I-Group mean YM value for the fiber direction stress–strain curve was 54% stiffer than that of H-Group (136.24 kPa versus 88.68 kPa). At end-systole, the mean YM values from the two groups were similar (175.84 kPa versus 200.2 kPa). More interestingly, H-Group end-systole mean YM was 126% higher that its end-diastole value, while I-Group end-systole mean YM was only 29% higher that its end-diastole value. This indicated that H-Group had much greater systole–diastole material stiffness variations. At beginning-of-ejection (BE), LV ejection fraction (LVEF) showed positive correlation with C-curvature, stress, and strain, and negative correlation with LV volume, respectively. At beginning-of-filling (BF), LVEF showed positive correlation with C-curvature and strain, but negative correlation with stress and LV volume, respectively. Using averaged values of two groups at BE, I-Group stress, strain, and wall thickness were 32%, 29%, and 18% lower (thinner), respectively, compared to those of H-Group. L-curvature from I-Group was 61% higher than that from H-Group. Difference in C-curvature between the two groups was not statistically significant. Our results indicated that our modeling approach has the potential to determine in vivo ventricle material properties, which in turn could lead to methods to infer presence of infarct from LV contractibility and material stiffness variations. Quantitative differences in LV volume, curvatures, stress, strain, and wall thickness between the two groups were provided.

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