Electronics Manufacturing with Lead-Free Halogen-Free and Conductive-Adhesive

671 Pages·2002·24.19 MB·English

by  John Lau

ELECTRONICS
MANUFACTURING
WITH LEAD-FREE,
HALOGEN-FREE,
AND CONDUCTIVE-ADHESIVE
MATERIALS
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ELECTRONICS
MANUFACTURING
WITH LEAD-FREE,
HALOGEN-FREE,
AND CONDUCTIVE-ADHESIVE
MATERIALS
John H. Lau
Agilent Technologies, Inc.
C. P. Wong
Georgia Institute of Technology
Ning-Cheng Lee
Indium Corporation of America
S. W. Ricky Lee
Hong Kong University of Science and Technology
Copyright © 2003 by The McGraw-Hill Companies, Inc. All rights reserved. Manufactured in the
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DOI: 10.1036/0071386246
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CONTENTS
Chapter 1. Introduction to Environmentally Benign
Electronics Manufacturing 1.1
1.1 Trends in Industry 1.1
1.1.1 Automobile Industry 1.1
1.1.2 Electronics Industry 1.2
1.2 Trends in Worldwide Environmentally Benign Manufacturing 1.3
1.2.1 Government Activity 1.4
1.2.2 Industry Activity 1.4
1.2.3 R&D Activity 1.5
1.2.4 Education Activity 1.5
1.2.5 Worldwide Efforts on Environmentally Benign
Electronics Manufacturing 1.6
1.3 Trends in Environmentally Benign Electronics Manufacturing 1.6
1.3.1 IC Fabrication 1.9
1.3.2 IC Packaging 1.9
1.3.3 PCBs 1.9
1.3.4 Lead-Free Solders 1.10
1.3.5 Halogen-Free Flame Retardants 1.11
1.3.6 Conductive Adhesives 1.12
1.3.7 End-Of-Life Management 1.13
Acknowledgments 1.14
References 1.14
Chapter 2. Chip (Wafer)-Level Interconnects with Lead-Free
Solder Bumps 2.1
2.1 Introduction 2.1
2.2 UBM 2.1
2.2.1 Electroless Ni-P-Immersion Au UBM 2.1
2.2.2 Al-NiV-Cu UBM 2.6
2.3 Microball Wafer Bumping with Lead-Free Solders 2.6
2.3.1 Overview of Microball Wafer Bumping 2.6
2.3.2 Microball Preparation 2.6
2.3.3 Microball Management 2.9
2.3.4 Microball Wafer Bumping 2.12
2.4 Sn-Ag-Cu Solder Ball Mounting on Wafers 2.12
2.4.1 WLCSP 2.12
2.4.2 WLCSP with Stress-Relaxation Layer 2.15
2.5 Stencil Printing on Sn-Ag Solder on Wafers with Ni-Au UBM 2.20
2.5.1 The Interface Between Electroless Ni and Solders 2.20
2.5.2 Growth of the IMC and P-Rich Ni Layer 2.22
2.5.3 Bump Shear Fracture Surface 2.24
v
vi CONTENTS
2.6 Stencil Printing of Sn-Cu, Sn-Ag-Bi, and Sn-Ag-Cu Solders
on Wafers with Ni-Au UBM 2.27
2.6.1 Interface of Reflowed Solder Bumps 2.27
2.6.2 Interface of Annealed Solder Bumps 2.29
2.6.3 Shear Strength of Solder Bumps 2.30
2.7 Stencil Printing of Sn-Cu, Sn-Ag-Bi, and Sn-Ag-Cu Solders
on Wafers with Ti-Cu UBM 2.31
2.7.1 Interface of Reflowed Solder Bumps 2.31
2.7.2 Interface of Annealed Solder Bumps 2.31
2.8 Paste Printing of Solders on Wafers with Al-NiV-Cu UBM 2.34
Acknowledgments 2.34
References 2.35
Chapter 3. WLCSP with Lead-Free Solder Bumps on PCB/Substrate 3.1
3.1 Introduction 3.1
3.2 Solder Joint Reliability of SnAgCu WLCSP with a
Stress-Relaxation Layer 3.1
3.2.1 Finite Element Results 3.1
3.2.2 Thermal Cycling Results 3.2
3.2.3 Effects of the Stress-Relaxation Layer on Capacitance 3.4
3.3 Solder Joint Reliability of SnAg and SnAgCu WLCSPs with
TiCu and NiAu UBMs 3.5
3.3.1 Isothermal Fatigue Test Results 3.5
3.3.2 Thermal Cycling Fatigue Test Results 3.8
3.4 Solder Joint Reliability of SnAg, SnAgCu, SnAgCuSb,
and SnAgInCu WLCSPs with AlNiVCu UBM 3.15
3.4.1 Thermal Fatigue of SnAg,SnAgCu,SnAgCuSb
and SnAgInCu WLCSPs on Ceramic Substrate 3.15
3.4.2 Thermal Fatigue of SnAgCu WLCSP on PCB 3.15
3.4.3 High-Temperature Storage of SnAgCu
WLCSP on PCB 3.15
3.4.4 Shear Strength of SnAgCu WLCSP on PCB 3.17
Acknowledgments 3.20
References 3.20
Chapter 4. Chip (Wafer)-Level Interconnects with Solderless Bumps 4.1
4.1 Introduction 4.1
4.2 Wafers for Electroless Ni-Au, Electroplated Au,
and Electroplated Cu Bumps 4.1
4.3 Electroless Ni-P-Immersion Au Bumps 4.1
4.3.1 Materials and Process 4.2
4.3.2 Passivation Cracking 4.2
4.4 Electroplated Au Bumps 4.6
4.4.1 Materials and Process 4.6
4.4.2 Bump Specifications and Measurement Methods 4.6
4.5 Electroplated Cu Bumps 4.8
4.5.1 Materials and Process 4.8
4.5.2 Special Considerations 4.8
CONTENTS vii
4.6 Electroplated Copper Wires 4.9
4.6.1 Structure 4.9
4.6.2 Fabrication Materials and Process 4.10
4.7 Wire-Bonding Microsprings 4.10
4.7.1 Materials and Process 4.11
4.7.2 Special Considerations 4.11
4.8 Wire-Bonding Au Stud Bumps 4.12
4.8.1 Materials and Process 4.12
4.8.2 Equipment 4.14
4.9 Wire-Bonding Cu Stud Bumps 4.17
4.9.1 Materials and Process 4.21
4.9.2 Shear Strength 4.23
Acknowledgments 4.23
References 4.24
Chapter 5. WLCSP with Solderless Bumps on PCB/Substrate 5.1
5.1 Introduction 5.1
5.2 Design, Materials, Process, and Reliability of WLCSPs
with Au Bumps, Cu Bumps, and Ni-Au Bumps on PCB with ACF 5.1
5.2.1 PCB 5.1
5.2.2 ACF 5.1
5.2.3 FCOB Assemblies with ACF 5.4
5.2.4 Thermal Cycling Test of FCOB Assemblies with ACF 5.9
5.2.5 SIR Test Results of ACF FCOB Assemblies 5.10
5.2.6 Summary 5.10
5.3 Copper Wired WLCSP with Solders or Adhesives on Substrates 5.11
5.4 Microspring WLCSP with Solders or Adhesives on PCB/Substrate 5.12
5.5 Au-Stud-Bumped WLCSP with ICA on PCB 5.12
5.5.1 Materials and Process Flow 5.13
5.5.2 Equipment for SBB Technology 5.14
5.6 Au-Stud-Bumped WLCSP with ICA on Flex 5.14
5.6.1 Materials and Process 5.16
5.6.2 Qualification Tests and Results 5.19
5.7 Au-Stud-Bumped WLCSP with ACP/ACF on PCB 5.22
5.7.1 ACF/ACP with Nonconductive Fillers 5.22
5.7.2 DSC Measurement Results 5.23
5.7.3 DMA Measurement Results 5.23
5.7.4 TMA Measurement Results 5.23
5.7.5 TGA Measurement Results 5.26
5.7.6 85°C/85% RH Test and Results 5.26
5.7.7 Thermal Cycling Test and Results 5.27
5.8 Au-Stud-Bumped WLCSP Diffused on Au-Plated PCB with NCA 5.29
5.8.1 Materials and Process 5.32
5.8.2 Reliability 5.35
5.9 Au-Stud-Bumped WLCSP Diffused on Au-Plated Flex with NCA 5.37
5.9.1 Materials and Process 5.37
5.9.2 Reliability 5.38
5.10 Cur-Stud-Bumped WLCSP with Lead-Free Solders on PCB 5.42
5.10.1 Materials and Process 5.42
5.10.2 Reliability 5.43
Acknowledgments 5.45
References 5.45
viii CONTENTS
Chapter 6. Environmentally Benign Molding Compounds
for IC Packages 6.1
6.1 Introduction 6.1
6.2 Environmentally Benign Molding Compounds for PQFP Packages 6.1
6.2.1 Flame Resistance Systems:Addition-Type Retardants 6.2
6.2.2 Flame Resistance Systems:Novel Resin Systems 6.4
6.2.3 Effects of Raised Reflow Temperature
on Molding Compounds 6.4
6.2.4 Halogen-Free Molding Compounds for Lead-Free Soldering 6.8
6.3 Environmentally Benign Molding Compounds
for PBGA Packages 6.10
6.3.1 Halogen-Free Flame-Retardant Agents 6.12
6.3.2 PBGA Package Warpage Controlled by T Dispersion 6.16
g
6.3.3 PBGA Package Warpage Controlled by
Stress-Absorbing Agents 6.19
6.4 Environmentally Benign Molding Compounds for
MAP-PBGA Packages 6.22
6.4.1 Halogen-Free Flame-Retardant Resins 6.22
6.4.2 Sample Preparation 6.22
6.4.3 Effects of T,Shrinkage,and Viscosity on Package
g
Coplanarity 6.25
6.4.4 Moisture Sensitivity Tests 6.27
Acknowledgments 6.29
References 6.29
Chapter 7. Environmentally Benign Die Attach Films for IC Packaging 7.1
7.1 Introduction 7.1
7.2 Environmentally Benign Die Attach Films 7.1
7.2.1 Silver-Filled Film DF-335-7 for Leadframe PQFP Packages 7.1
7.2.2 Insulating Film DF-400 for BT-Substrate PBGA Packages 7.6
7.3 Environmentally Benign In-Sn Die Attach Bonding Technique 7.10
7.3.1 In-Sn Phase Diagram 7.11
7.3.2 Design and Process of In-Sn Solder Joints 7.12
7.3.3 Characterization of In-Sn Solder Joints 7.14
Acknowledgments 7.18
References 7.18
Chapter 8. Environmental Issues for Conventional PCBs 8.1
8.1 Introduction 8.1
8.2 Influence of Electronic Products 8.2
8.2.1 Major Environmental Concerns 8.2
8.2.2 Energy Issues 8.5
8.2.3 Chemical Issues 8.7
8.2.4 Disposal and Recycling 8.14
8.2.5 Design for Environment 8.16
8.3 Environmental Research for the PCB Industry 8.18
8.3.1 Energy and Solvent Reduction 8.19
8.3.2 Renewable Resins for PCB 8.21
8.3.3 Reworkable Encapsulants for Disassembly 8.22