Moisture Sensitivity of Plastic Packages of IC Devices

Foreword

Preface

Series Preface

Contents

Contributors

1 Fundamental Characteristics of Moisture Transport, Diffusion, and the Moisture-Induced Damages in Polymeric Materials in Electronic Packaging

1.1 Introduction

1.2 Fickian and Non-Fickian Moisture Diffusion

1.3 Saturated Moisture Concentration

1.4 Water Sorption and Moisture Sorption

1.5 Characterization of Pore Size, Porosity, and Free Volume

1.6 Hygroscopic Swelling Measurement

1.7 Effect of Moisture on Fracture Toughness/Adhesion Strength

1.7.1 In Situ Fracture Toughness Measurement

1.7.2 Die Shear Test

1.8 Discussions

1.8.1 State of Moisture in Polymers

1.8.2 Total Moisture Volume Versus Volume Expansion Due to Hygroscopic Swelling

1.8.3 Effect of Fillers

1.8.4 Duration of the Moisture Diffusion

1.9 Concluding Remarks

References

2 Mechanism of Moisture Diffusion, Hygroscopic Swelling, and Adhesion Degradation in Epoxy Molding Compounds

2.1 Introduction

2.2 Moisture Diffusion in Plastic Encapsulated Microcircuits

2.2.1 Moisture Diffusion in a Package vs. in Bulk EMC

2.2.2 Interfacial Moisture Diffusion

2.2.3 Moisture Accommodation at Interfaces

2.2.4 Fickian Moisture Diffusion

2.2.5 Non-Fickian Dual-Stage Moisture Diffusion

2.3 Moisture Desorption

2.4 Second Run of Absorption (Re-sorption)

2.5 Hygroscopic Swelling

2.5.1 Characterization of CHS by Warpage Measurement of Bi-material Beams

2.5.2 Characterization of CHS by TMA/TGA

2.5.3 Characterization of CHS by Archimedes Principle

2.6 Moisture-Induced Adhesion Degradation

2.7 Conclusion

References

3 Real-Time Characterization of Moisture Absorptionand Desorption

3.1 Introduction

3.2 Background

3.3 Experimental Data

3.3.1 Material

3.3.2 Instrumentation

3.4 Moisture AbsorptionDesorption

3.4.1 Moisture Diffusivity

3.4.2 Saturated Moisture Content

3.4.3 Temperature Dependence of Diffusivity

3.5 Comparison with Literature Data

3.6 Application Moisture Diffusion and Vapor Pressure Modeling for Ultrathin Stacked Chip Scale Packages

3.7 Conclusions

References

4 Modeling of Moisture Diffusion and Whole-Field Vapor Pressure in Plastic Packages of IC Devices

4.1 Introduction

4.2 Moisture Diffusion Modeling Normalization Method

4.2.1 Theory

4.2.2 Thermal-Moisture Analogy

4.2.3 Example -- Application to a PBGA Package

4.3 Moisture Desorption Modeling Direct Moisture Concentration (DCA) Approach

4.3.1 Theory

4.3.2 Numerical Implementation

4.3.3 Verification

4.3.4 Analysis of Moisture Desorption for a Bi-material Model

4.3.5 Example -- Application to a PBGA Package

4.4 Whole-Field Vapor Pressure Model

4.4.1 Theory

4.4.2 Numerical Implementation

4.4.3 Analysis of Vapor Pressure Development During Reflow for a Bi-material Model

4.4.4 Whole-Field Vapor Pressure Modeling for FCBGA and PBGA Packages

4.5 Summary

Appendix: Table of the Saturated Water Vapor Density and Vapor Pressure at Different Temperatures

References

5 Characterization of Hygroscopic Deformations by Moir Interferometry

5.1 Introduction

5.2 Moir Interferometry

5.2.1 Real-Time Observation and Testing Apparatus

5.2.2 Tuning and Measurement

5.3 Experimental Procedure Using Moir Interferometry

5.3.1 Initial Preparation

5.3.2 Specimen Grating Replication

5.3.3 Moisture Content Measurement

5.3.4 Measurement of Hygroscopic Deformation

5.4 Hygroscopic Swelling Measurement of Mold Compounds

5.4.1 CHS of Mold Compounds

5.4.2 Comparison Between Hygroscopic and Thermal Deformations

5.4.3 Effect of Grating on Sorption and Desorption Characteristics of the Mold Compound

5.4.4 CHS Measurement Accuracy

5.5 Analysis of Plastic Quad Flat Package

5.5.1 Discussion

5.6 Summary

References

6 Characterization of Interfacial Hydrothermal Strength of Sandwiched Assembly Using Photomechanics Measurement Techniques

6.1 Introduction

6.2 Interfacial Fracture Mechanics Approach

6.3 Photomechanics Measurement Techniques

6.3.1 Moiré Interferometry

6.3.2 Digital Image Correlation (DIC)

6.4 Experimental Procedures for Interfacial Hydrothermal Strength Characterization

6.4.1 Specimen Preparation

6.4.2 Measurement of Thermal and Hygrothermal Deformation

6.4.3 Determination of Critical Interfacial Fracture Toughness

6.5 Interfacial Hydrothermal Strength of Sandwiched Assembly

6.5.1 Hygrothermal Displacement of the Assembly

6.5.2 Thermal Deformation of the Assembly

6.5.3 Fracture Toughness of the Assembly Under Hygrothermal Aging

6.5.4 Critical Interfacial Fracture Toughness of the Assembly

6.5.5 Reliability of Silicon/Underfill Interface of the Assembly

6.6 Summary

References

7 Hygroscopic Swelling of Polymeric Materials in Electronic Packaging: Characterization and Analysis

7.1 Introduction

7.2 Hygroscopic Swelling Characterization Using Point-Measurement Methods

7.3 Effect of Non-uniform Moisture Distribution in Determining CHS

7.3.1 Moisture Distribution

7.3.2 Hygroscopic Swelling-Induced Deformation

7.3.3 Averaged Approaches

7.3.3.1 Averaged Approach I

7.3.3.2 Averaged Approach II

7.3.4 Results

7.4 Effect of Hygroscopic Stress in Determining CHS

7.4.1 Problem Description

7.4.2 Theory -- Sequentially Coupled Field Transient Analysis

7.4.3 Results

7.5 General Guidelines for Characterizing Hygroscopic Swelling Properties

7.6 Coupled Nonlinear ThermalHygroscopic Stress Modeling

7.7 Conclusions

References

8 Modeling of Moisture Diffusion and Moisture-Induced Stresses in Semiconductor and MEMS Packages

8.1 Introduction

8.2 Technical Background

8.2.1 Moisture Diffusion

8.2.2 Analytical Solutions of Diffusion Equation

8.2.3 Hygroscopic Swelling

8.3 Modeling of Moisture Diffusion

8.3.1 Thermal--Moisture Analogy

8.3.1.1 Single Material Problems

8.3.1.2 Interfacial Discontinuity in Multi-material Problems

8.3.1.3 Normalized Analogy

8.3.1.4 Advanced Analogy

8.3.1.5 Validation of Analogies

8.3.2 Moisture Transport into/out of a Cavity: Effective-Volume Scheme

8.4 Modeling of Hygroscopic Swelling-Induced Stresses

8.4.1 Modeling Strategy for Hygro-thermo-mechanical Stress Analysis

8.4.2 Implementation Using ABAQUS

8.4.3 Verification of the Modeling Scheme

8.4.4 Discussion: Implementation Using ANSYS

8.5 Application to a Polymer Bi-material Structure

8.5.1 Bi-material Specimen

8.5.2 Experimental Procedure

8.5.3 Simulation Procedure

8.5.4 Validation of the FE Model

A.1 FDM Schemes for Mass Diffusion Equations

A.1.1 Anisothermal 1-D Problem

A.1.2 Isothermal Axisymmetric Problem

A.2 ANSYS Input Templates for the Advance Analogy

A.2.1 Transient Case

A.2.2 Anisothermal Case

A.3 Templates for the Combined Analysis

A.3.1 Program to Change the Record Key

A.3.2 Example Program for UEXPAN

A.3.3 ANSYS Input Template for Hygro-Thermal Loading

References

9 Methodology for Integrated Vapor Pressure, Hygroswelling, and Thermo-mechanical Stress Modeling of IC Packages

9.1 Introduction

9.2 Moisture Diffusion Modeling

9.2.1 Modeling Methodology

9.2.2 Modeling Results

9.3 Thermal Modeling

9.3.1 Modeling Methodology

9.3.2 Modeling Results

9.4 Vapor Pressure Modeling [11]

9.4.1 Modeling Methodology

9.4.2 Modeling Results

9.5 Hygro-mechanical Modeling

9.6 Thermo-mechanical Modeling

9.7 Integrated Stress Modeling

9.7.1 Modeling Methodology

9.7.2 Modeling Results

9.8 Interfacial Fracture Mechanics Modeling

9.8.1 Modeling Methodology

9.8.2 Modeling Results

9.9 Integrated Stress Modeling for a Pressure Cooker Test

9.9.1 Modeling Methodology

9.9.2 Moisture Diffusion

9.9.3 Hygro-mechanical Stress During PCT

9.9.4 Combined Hygro-mechanical Stress and Thermo-mechanical Stress During PCT

9.10 Conclusions

References

10 Failure Criterion for Moisture-Sensitive Plastic Packages of Integrated Circuit (IC) Devices: Application and Extension of the Theory of Thin Plates of Large Deflections

10.1 Introduction

10.2 Analysis

10.2.1 Constitutive Equations

10.2.2 Boundary Conditions

10.2.3 Stresses

10.2.4 Special Cases

10.2.5 Initial Curvature and Initial Stresses

10.2.6 Elongated Package

10.2.7 von Mises Stress

10.2.8 Simplified Approach

10.3 Numerical Examples

10.4 Calculated Data

10.5 Conclusions

Appendix. Clamped Plate of Finite Aspect Ratio Experiencing Large Deflections

References

11 Continuum Theory in Moisture-Induced Failures of Encapsulated IC Devices

11.1 Introduction

11.2 Instability of Single Void Growth

11.2.1 Elasto-Plastic Model

11.2.2 Hyperelastic Model

11.3 Void Behavior at the Interface

11.4 Extension of the Gurson Model and Void Evolution Rate

11.5 A Rigid-Plastic Model for Package Bulging Analysis

11.6 Governing Equations for a Deforming Polymer with Moisture Considering Phase Transition

11.7 Concluding Remarks

References

12 Mechanism-Based Modeling of Thermal- and Moisture-Induced Failure of IC Devices

12.1 Introduction

12.2 Vapor Pressure Modeling in Rate-Independent ElasticPlastic Solids

12.3 Vapor Pressure and Residual Stress Effects

12.3.1 Adhesive Failure Mechanisms

12.3.2 Interfacial Toughness

12.3.2.1 Parallel Delamination Along Interfaces of Adhesive Joints

12.3.2.2 Interfacial Toughness Under Mixed Mode Loading

12.3.3 Full-Field Analysis of IC Packages

12.4 Pressure Sensitivity and Plastic Dilatancy Contributions

12.4.1 Macroscopic Response on Void Growth and Interaction

12.4.2 Extended Damage Zone Formation

12.5 Porous Solids with Pressure-Sensitivity and Non-linear Viscosity

12.5.1 Pressure Sensitivity, Dilatancy, and Softening--Rehardening

12.5.2 Nonlinear Viscosity

References

13 New Method for Equivalent Acceleration of IPC/JEDEC Moisture Sensitivity Levels

13.1 Introduction

13.2 Moisture Sensitivity Test Classifications Joint IPC/JEDEC Industry Standard J-STD-020D

13.3 Local Moisture Concentration Equivalency-Based Method [ 2 ]

13.3.1 Theory

13.3.2 Experimental Validations

13.3.3 Discussions

13.4 New Method for Equivalent Acceleration of IPC/JEDEC Moisture Sensitivity Test

13.4.1 Methodology

13.4.2 Finite Element Modeling

13.4.3 Experimental Validation

13.5 Conclusions

References

14 Moisture Sensitivity Level (MSL) Capability of Plastic-Encapsulated Packages

14.1 Introduction

14.2 Experimental Procedures and Setup

14.2.1 Mold Compound Chemistry/Properties

14.2.2 Tensile Pull Sample Description/Instron Machine Setup

14.2.3 Moisture Absorption Samples

14.2.4 Moisture Sensitivity Testing

14.2.5 QFN Package Description

14.2.6 D 2 Pak Package Description

14.3 Experimental Data and Analysis

14.3.1 First Series of Experiments

14.3.1.1 Pull Tab Adhesion Data

14.3.1.2 Moisture Absorption

14.3.1.3 Correlation of Adhesion and Moisture Absorption with Package MSL Performance

14.3.1.4 Experimental Conclusions for Mold Compound Chemistry Experiments

14.3.2 Second Series of Experiments

14.3.2.1 Pull Tab Adhesion

14.3.2.2 Moisture Sensitivity Testing (Level 1at 260C)

14.3.2.3 Experimental Conclusions for the Second Series of Experiments

14.3.3 Additional Experimental Studies

14.3.3.1 Effect of Mold Cap Thickness of QFN Packages

14.3.3.2 Effect of Mold Compound Compaction

14.4 Conclusions

References

15 Hygrothermal Delamination Analysis of Quad Flat No-Lead (QFN) Packages

15.1 Introduction

15.2 Manufacture of Dummy QFN Packages

15.3 Mechanical Tests for Interfacial Strength

15.4 Moisture Sensitivity Tests of Dummy QFN Packages

15.5 Finite Element Model

15.6 Thermo-mechanical Stress Analysis

15.7 Hygro-mechanical Stress Analysis

15.8 Integrated Stress Analysis

15.9 Discussion

15.10 Concluding Remarks

References

16 Industrial Applications of Moisture-Related ReliabilityProblems

16.1 Introduction

16.2 Application 1: Wire Bond Reliability of a BGA Package Subjected to HAST

16.2.1 Description of the Carrier

16.2.2 Material Characterization

16.2.3 Finite Element Modeling

16.2.4 Results

16.3 Application 2: Moisture-Related Structural Similarity Rules

16.3.1 Description of the Carrier

16.3.2 Material Characterization

16.3.3 Finite Element Modeling

16.3.4 Results

16.4 Application 3: Moisture Sensitivity of System-in-Packages

16.4.1 Carrier Description

16.4.2 Finite Element Modeling

16.4.3 Results

16.5 Conclusions

References

17 Underfill Selection Against Moisture in Flip ChipBGA Packages

17.1 Introduction

17.2 Design of Experiments

17.2.1 Test Vehicles

17.2.2 ''No-flux'' Assembly Process

17.2.3 Plasma Grafting Surface Treatment

17.2.4 Underfill Voiding

17.3 Material Characterization

17.3.1 Thermo-Mechanical Properties

17.3.2 Moisture Diffusivity and Saturated Moisture Concentration

17.3.3 Pull/Shear Adhesion Test and Results

17.4 Moisture/Reflow Sensitivity Test Results and Failure Analysis

17.4.1 Effect of the Underfill Material Selection

17.4.2 Failure Mode Analysis

17.4.3 Effect of Flux Residue

17.4.4 Effect of Plasma Grafting Treatment

17.4.5 Effect of Overmolding

17.4.6 Effect of Voids in Underfill

17.5 Finite Element Modeling

17.5.1 Vapor Pressure Modeling

17.5.2 Thermal Stress Analysis on Overmolding Effect

17.6 Integrated Analysis of Moisture-Induced Delamination at Reflow

17.7 Conclusions

References

18 Moisture Sensitivity Investigations of 3D Stacked-Die Chip-Scale Packages (SCSPs)

18.1 Introduction

18.2 Experimental

18.2.1 Test Vehicle Description

18.2.2 Reflow Profile Setting

18.2.3 Substrate Design

18.2.4 Die-Attach Film Selection

18.2.5 Material Properties of Die-Attach Films

18.2.6 Moisture/Reflow Sensitivity Test Procedures

18.3 Test Results and Failure Analysis

18.3.1 Effect of Reflow Profiles

18.3.2 Effect of Substrate Design

18.3.3 Evaluation of Different Die-Attach Films

18.4 Finite Element Analysis

18.4.1 Effect of Substrate Thickness

18.4.2 Effect of Reflow Profile

18.5 Summary

References

19 Automated Simulation System of Moisture Diffusion and Hygrothermal Stress for Microelectronic Packaging

19.1 Introduction

19.2 Basic Formulations

19.2.1 Moisture Diffusion and Hygroswelling

19.2.2 Vapor Pressure Model

19.2.3 Equivalent Coefficient of Thermal Expansion (CTE)

19.3 Development of Automated Simulation System for Moisture Diffusion and Hygrothermal Stress

19.3.1 ANSYS Workbench Overview

19.3.2 General Package Automated Simulation Platform

19.3.3 Structure of AutoSim in Moisture-Related Analysis

19.3.3.1 Modules of Moisture-Related Automated Simulation System

19.4 Application of AutoSim

19.4.1 Moisture Diffusion Analysis for an MLP Package

19.4.1.1 Moisture Diffusion

19.4.1.2 Vapor Pressure Simulation

19.4.1.3 Integrated Stress Modeling

19.4.2 Material Parameter Examination

19.5 Conclusion

References

20 Moisture-Driven Electromigrative Degradation in Microelectronic Packages

20.1 Introduction

20.2 Electrochemical Migration (ECM)

20.3 ECM Mechanism

20.4 ECM: Contributing Factors

20.4.1 Moisture (Humidity) Factor

20.4.2 Voltage Factor

20.4.3 Temperature Factor

20.4.4 Material Factor

20.4.5 Effect of Ionic Contaminants: Complexation and Metal-Ion Liberation

20.4.6 Effect of Contaminants on Water Uptake

20.5 Mechanism of Ion Transport in ECM

20.6 Dendritic Morphology

20.7 Summary

References

21 Interfacial Moisture Diffusion: Molecular Dynamics Simulation and Experimental Evaluation

21.1 Introduction

21.2 Molecular Dynamics Simulation of Moisture Diffusion

21.2.1 Molecular Dynamics Simulation

21.2.2 Molecular Dynamics Models of Moisture Diffusion

21.2.3 Effect of Interfacial Adhesion of Copper/Epoxy Under Different Moisture Levels

21.3 Experimental Methods on Detecting Interfacial Moisture Diffusion

21.3.1 Background

21.3.2 Interfacial Moisture Diffusion Measurement Example

21.3.2.1 Sample Preparation

21.3.2.2 FTIR--MIR Measurement

21.3.2.3 FTIR--MIR Signal Calibration

21.3.2.4 Results of FTIR--MIR Measurement

21.3.3 Effect of Copper Oxide Content Under Interfacial Moisture Diffusion on Adhesion

21.3.3.1 Work of Adhesion

21.3.3.2 X-Ray Photoelectron Spectroscopy

21.3.3.3 Moisture and Copper Oxide-Related Adhesion

21.4 Summary

References

About the Editors

Subject Index