Green electronics manufacturing: creating environmental sensible products

350 Pages·2013·3.065 MB·English

by  John X Wang

K11301_cover.fhmx 6/19/12 10:31 AM Page 1
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MANUFACTURING AND INDUSTRIAL ENGINEERING Wang
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Creating Environmental Sensible Products
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“… a very useful addition to currently available literature. … written in language that
is very clear … practical as well as thorough in its approach.” EE
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—Marvin Roush, Professor Emeritus, Reliability Engineering, University of Maryland

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“… clearly the result of high quality work done by a very competent person. Dr. Wang
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manages to make available a very complex subject for both the experienced reader
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as well as for the inexperienced reader. … The book gives a very comprehensive
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description of the multidisciplinary approach to reduce the energy- and material-
intensiveness of manufacturing electronic components.” TT
—Dr. Rune Reinertsen, Eni Norge AS, Norway RR
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“… very thorough and knowledgeable. I have copies of his previous books and use
them as reference material often. I have no doubt that this book will be as valuable NN
as his others.” II
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—Vincent S. Lyons, Leggett & Platt, Incorporated
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Features
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• Includes a systems engineering approach to help implement green electronics
manufacturing systematically
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• Addresses thermal and vibration analysis of green electronic products
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• Covers proactive reliability engineering and risk management of
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green electronic products
• Presents advanced modeling analysis of green electronic systems FF
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• Discusses methods for green electronic circuit analysis
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Going “green” is becoming a major component of the mission for electronics
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manufacturers worldwide. Although this goal seems simplistic, it poses daunting
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dilemmas. Yet, to compete effectively in the global economy, manufacturers must
take the initiative to drive this crucial movement. Green Electronics Manufacturing: RR
Creating Environmental Sensible Products provides you with a complete reference
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to design, develop, build, and install an electronic product with special consideration NN
for the product’s environmental impacts during its whole life cycle.
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John X. Wang
6000 Broken Sound Parkway, NW K11301
Suite 300, Boca Raton, FL 33487
711 Third Avenue
an informa business New York, NY 10017
www.crcpress.com 2 Park Square, Milton Park
Abingdon, Oxon OX14 4RN, UK
www.crcpress.com
Composite
GREEN
ELECTRONICS
MANUFACTURING
Creating Environmental
Sensible Products
John X. Wang
Boca Raton London New York
CRC Press is an imprint of the
Taylor & Francis Group, an informa business
CRC Press
Taylor & Francis Group
6000 Broken Sound Parkway NW, Suite 300
Boca Raton, FL 33487-2742
© 2013 by Taylor & Francis Group, LLC
CRC Press is an imprint of Taylor & Francis Group, an Informa business
No claim to original U.S. Government works
Version Date: 20120518
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To
my home
by the green woods
of Michigan
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Contents
Preface ...................................................................................................................xiii
About the Author ..................................................................................................xv
1. Green Electronic Assembly: Strategic Industry Interconnection
Direction ...........................................................................................................1
1.1 Starting from Your Personal Electronic Lab: Review
the Soldering Process ...........................................................................1
1.1.1 Flux in Soldering ......................................................................2
1.1.2 Solder Melting Temperature ..................................................2
1.1.3 Tip Temperature .......................................................................2
1.1.4 Soldering Iron ...........................................................................3
1.1.5 Soldering Guns .........................................................................3
1.1.6 Ensure Proper Cleanliness .....................................................3
1.1.7 Resoldering ...............................................................................3
1.2 Lead-Free Solder Tip .............................................................................4
1.3 Lead-Free Solder Bumps ......................................................................5
1.4 Flip-Chip Technology ...........................................................................6
1.5 Flip-Chip Assembly Process ...............................................................7
1.5.1 Significant Impacts on Reliability .........................................7
1.5.2 Placement Stage ........................................................................8
1.5.3 Protection against Deformation .............................................8
1.5.4 Yield of the Placement Process...............................................9
1.5.5 Underfill Stage ..........................................................................9
1.5.6 Need for Process Optimization .............................................9
1.5.7 Prevention of Contamination and Moisture ........................9
1.5.8 Inspection and Testing ..........................................................10
1.5.9 Process Capability..................................................................10
1.5.10 Quality Control ......................................................................10
1.5.11 Testability ................................................................................11
1.5.12 Integrate Flip Chip into Standard Surface-Mount
Technology Process ...............................................................11
1.6 Mechanical Stress and Electromigration .........................................12
1.6.1 Coupling of Two Trends ........................................................12
1.6.2 Electromigration ....................................................................12
1.6.3 Wind Force Equation .............................................................12
1.7 Residual Mechanical Stress ...............................................................15
1.8 Mitigate Deterioration of Lead-Free Tin Solder at Low
Temperatures .......................................................................................16
1.8.1 Tin Plague ...............................................................................16
1.8.2 How to Mitigate Tin Plague .................................................16
v
vi Contents
1.9 Able to “Take the Heat?”: Capability to Withstand
High Temperature ...............................................................................17
1.10 Solder Joint Fatigue .............................................................................20
1.11 Finite Element Analysis .....................................................................21
Bibliography ...................................................................................................22
2. Tin Whiskers: New Challenge for Long-Term RoHS Reliability .......25
2.1 Tin Whisker Growth in Lead-Free Electronics ...............................25
2.1.1 Nomenclature .........................................................................27
2.2 Variability with Tin Whisker Mechanisms .....................................28
2.3 Tin Whisker Risk: Lesson from the Nuclear Industry ..................29
2.4 What Are Tin Whiskers? ....................................................................30
2.5 What Factors Influence Whisker Growth? ......................................31
2.5.1 Residual Stresses within the Tin Plating ............................31
2.5.2 Intermetallic Formation ........................................................31
2.5.3 Diffusion of Substrate Material into Tin Plating ...............32
2.5.4 Coefficient of Thermal Expansion Mismatches .................33
2.5.5 External Factors Induce Residual Stresses .........................33
2.6 Why Whiskers Are a Serious Reliability Risk
to Electronic Assemblies ....................................................................33
2.6.1 Stable Short-Circuits in Low-Voltage,
High-Impedance Circuits .....................................................34
2.6.2 Transient Short-Circuits ........................................................34
2.6.3 Metal Vapor Arc .....................................................................35
2.6.4 Debris/Contamination ..........................................................35
2.7 How to Mitigate Tin Whisker Risk ...................................................36
2.8 Use Finite Element Modeling to Assess Tin Whisker Risk ...........39
2.8.1 Allotropic Transformation of Tin ........................................39
2.8.2 Diffusion and the Formation of Copper–Tin
Intermetallics ..........................................................................39
2.8.3 Oxidation of Tin .....................................................................40
2.8.4 Excessive Energy Theory ......................................................40
2.8.5 Cracked Oxide Theory ..........................................................41
2.9 How to Evaluate Tin Whisker Impact on High-Reliability
Applications .........................................................................................43
Bibliography ...................................................................................................44
3. Fatigue Characterization of Lead-Free Solders ......................................45
3.1 Surface-Mount Technology................................................................45
3.2 Fatigue and Thermal Fatigue of Solder Joints.................................46
3.2.1 Solder Joint Fatigue ................................................................46
3.2.2 Thermal Fatigue of Solder Joint ...........................................47
3.2.3 Shear Strain .............................................................................49
3.2.4 Coffin–Manson Relationship for Thermal Fatigue ...........50
3.2.4.1 Example 3.1 ..............................................................51
Contents vii
3.3 Fatigue, Microstructure, and Microstructural Aging ....................53
3.3.1 Microstructure and Microstructural Aging ......................53
3.3.2 Mechanical Characterization ...............................................54
3.3.3 Stress Relaxation Testing ......................................................56
3.3.4 Finite Element Modeling ......................................................57
3.3.5 Fatigue Criteria .......................................................................58
3.3.5.1 Polymer PCBs: FR4, FR5 ........................................59
3.3.6 Ceramic PCBs .........................................................................60
3.3.7 Soldering .................................................................................63
3.3.8 Issues with Lead-Free Solder ...............................................65
Bibliography ...................................................................................................65
4. Lead-Free Electronic Reliability: Finite Element Modeling ................67
4.1 Finite Element Modeling and Inelastic Strain
Energy Density ............................................................................68
4.2 FEM Model Description .....................................................................70
4.2.1 FEM Variables .........................................................................70
4.2.1.1 Geometry .................................................................70
4.2.1.2 Material ....................................................................70
4.2.1.3 Elements Used ........................................................71
4.2.1.4 PCB Material Layers ..............................................72
4.2.2 Material Properties for FEM .................................................73
4.2.2.1 Linear Material Properties ....................................73
4.2.2.2 Nonlinear Solder Properties .................................73
4.3 Inelastic Strain Energy Density ........................................................76
4.4 Material Characterizaton of Underfill Materials ............................77
4.4.1 FP 4526 as an Underfill Material ..........................................77
4.4.2 FP 4549 as an Underfill Material ..........................................78
4.4.3 3M UF3667 as an Underfill Material ...................................80
4.4.4 Kester 9110S as an Underfill Material .................................80
4.4.5 Kester 9110 SBB as an Underfill Material ............................81
4.4.6 Effect of Measured Properties on the Simulation
Results ..................................................................................81
4.5 Solder Joint Integrity in Accelerated Thermal Cycling .................82
4.6 Life Prediction and Field Life Correlation with ATC Life ............84
4.6.1 Theory of Life Prediction ......................................................84
4.6.2 Energy Partitioning Methodology ......................................85
4.6.3 Time-Dependent Creep Model ............................................87
Bibliography ...................................................................................................88
5. Lead-Free Electronic Reliability: Fatigue Life Model ...........................91
5.1 Time-Independent Plasticity Model .................................................92
5.2 Fatigue Life Prediction Models .........................................................93
5.2.1 Eutectic (Sn–Pb–Ag) Solder ..................................................93
5.2.2 Lead-Free (Sn–Ag–Cu) Solder ..............................................96
viii Contents
5.3 Life Prediction Calculation Using Darveaux’s
Energy-Based Model ...........................................................................97
5.3.1 Motorola/Darveaux’s Constitutive Model .........................97
5.4 Solder Joint Integrity in Accelerated Thermal Cycling ...............104
5.4.1 Effect of Solder Joint Material Composition ....................105
5.4.2 Effect of Underfill Composition .........................................107
5.4.3 Effect of Bump Gap Height ................................................108
5.4.4 Effect of Bump Size ..............................................................109
5.5 Effect of T of the Underfill Material ..............................................112
g
Bibliography .................................................................................................113
6. Lead-Free Electronic Reliability: Higher Temperature ......................117
6.1 Computer Coupling of Phase Diagrams and
Thermochemistry and Differential Thermal Analysis ...............117
6.2 Solder Joint Integrity in Accelerated Thermal Cycling
0°C to 90°C .........................................................................................119
6.2.1 Effect of Solder Joint Material Composition ....................122
6.2.2 Effect of Underfill Composition .........................................123
6.2.3 Effect of Bump Gap Height ................................................125
6.2.4 Effect of Bump Size ..............................................................126
6.2.5 Summary of Simulation Results ........................................128
6.3 Field Profiles ......................................................................................128
6.3.1 Field Profile-1 ........................................................................131
6.3.2 Field Profile-2 ........................................................................132
6.3.3 Field Profile-3 ........................................................................133
6.4 Relative Damage Index ....................................................................134
Bibliography .................................................................................................137
7. Fatigue Design of Lead-Free Electronics and Weibull
Distribution ...........................................................................................141
7.1 Fatigue Design of Lead-Free Electronics .......................................141
7.2 Weibull Distribution for Life Testing Data Analysis ...................143
7.2.1 Mathematical Model ............................................................144
7.2.2 Data Fitting Method ............................................................147
7.2.2.1 Relationship between Shape Parameters
of Weibull and Lognormal Distributions .........149
7.2.2.2 Relationship between Scale Parameters
of Weibull and Lognormal Distributions .......155
7.3 Fatigue Life Prediction Based on Field Profile ..............................163
7.3.1 Field Profile-1 ........................................................................164
7.3.2 Field Profile-2 ........................................................................165
7.3.3 Field Profile-3 ........................................................................167
7.4 Copper Trace Integrity .....................................................................168
7.5 Fatigue Validation of Lead-Free Circuit Card Assembly ..........169
Contents ix
7.5.1 Circuit Card Assembly and Drive-Level Tests ................170
7.5.1.1 Life Prediction Calculation Using
Darveaux’s Energy-Based Model .......................170
7.5.2 CCA Component-Level Accelerated Test .........................171
Bibliography .................................................................................................172
8. Enhancing Reliability of Ball Grid Array .............................................175
8.1 Thermally Enhanced BGA ...............................................................176
8.2 Typical TEBGA Package and Finite Element Modeling ..............179
8.2.1 Fatigue Life Prediction ........................................................181
8.3 Finite-Volume-Weighted Averaging Technique ...........................182
8.4 Parametric Design of TEBGA Reliability ......................................184
8.4.1 Effect of Die Thickness........................................................185
8.4.2 Effect of Die Size ..................................................................186
8.4.3 Effect of PCB Thickness ......................................................187
8.4.4 Effect of Die Attach Adhesive Thickness .........................188
8.4.5 Effect of Heat Spreader Thickness.....................................189
8.4.6 Effect of BT Substrate Thickness .......................................189
8.4.7 Effect of BT/FR-4 CTE .........................................................189
8.4.8 Effect of FR-4 Young’s Modulus.........................................191
Bibliography .................................................................................................192
9. Finite Element Modeling under High-Vibration
and High-Temperature Environments ...................................................197
9.1 Lead versus Lead-Free Solder .........................................................198
9.2 Analytical Model: PCB Normal Modes and Displacement ........200
9.3 Finite Element Model: Random Vibration .....................................203
9.4 FEM Model Optimization under High-Vibration
Environment ....................................................................................206
9.5 FEM Model Validation under High-Temperature
Environment ....................................................................................206
Bibliography .................................................................................................210
10. Probabilistic Modeling of the Elastic-Plastic Behavior
of 63Sn-37Pb Solder Alloys ......................................................................213
10.1 Continuum Damage Mechanics .....................................................215
10.2 Probabilistic Continuum Damage Mechanics Model .....................219
10.2.1 Creep–Time-Dependent Deformation and
Uncertainty ........................................................................219
10.2.2 Thermodynamic Representation of Damage ...................221
10.2.3 Mechanical Representation of Damage ............................222
10.2.4 Stochastic Creep Damage Growth Prediction .................224
10.2.5 Neural Networks .................................................................226