Lead-free Solders

K. N. Subramanian is Professor of Materials Science and Engineering at Michigan State University. He has been a full-time faculty member at MSU for over 45 years. For the last 15 years he has devoted all his research efforts to lead-free electronic solders.

• Series Preface xv Preface xviiList of Contributors xixThematic Area I: Introduction 11 Reliability of Lead-Free Electronic Solder Interconnects: Roles of Material and Service Parameters 3K. N. Subramanian1.1 Material Design for Reliable Lead-Free Electronic Solders Joints 31.2 Imposed Fields and the Solder Joint Responses that Affect Their Reliability 51.3 Mechanical Integrity 51.4 Thermomechanical Fatigue (TMF) 61.5 Whisker Growth 71.6 Electromigration (EM) 71.7 Thermomigration (TM) 81.8 Other Potential Issues 8Thematic Area II: Phase Diagrams and Alloying Concepts 112 Phase Diagrams and Their Applications in Pb-Free Soldering 13Sinn-wen Chen, Wojciech Gierlotka, Hsin-jay Wu, and Shih-kang Lin2.1 Introduction 142.2 Phase Diagrams of Pb-Free Solder Systems 142.3 Example of Applications 232.4 Conclusions 393 Phase Diagrams and Alloy Development 45Alan Dinsdale, Andy Watson, Ales Kroupa, Jan Vrestal, Adela Zemanova, and Pavel Broz3.1 Introduction 453.2 Computational Thermodynamics as a Research Tool 483.3 Thermodynamic Databases – the Underlying Basis of the Modelling of Phase Diagrams and Thermodynamic Properties, Databases for Lead-Free Solders 513.4 Application of the SOLDERS Database to Alloy Development 573.5 Conclusions 684 Interaction of Sn-based Solders with Ni(P) Substrates: Phase Equilibria and Thermochemistry 71Clemens Schmetterer, Rajesh Ganesan, and Herbert Ipser4.1 Introduction 724.2 Binary Phase Equilibria 734.3 Ternary Phase Equilibria Ni-P-Sn 854.4 Thermochemical Data 944.5 Relevance of the Results and Conclusion 111Thematic Area III: Microalloying to Improve Reliability 1195 'Effects of Minor Alloying Additions on the Properties and Reliability of Pb-Free Solders and Joints' 121Sung K. Kang5.1 Introduction 1225.2 Controlling Ag3Sn Plate Formation 1255.3 Controlling the Undercooling of Sn Solidification 1325.4 Controlling Interfacial Reactions 1365.5 Modifying the Microstructure of SAC 1455.6 Improving Mechanical Properties 1495.7 Enhancing Electromigration Resistance 1515.8 Summary 1536 Development and Characterization of Nano-composite Solder 161Johan Liu, Si Chen, and Lilei Ye6.1 Introduction 1626.2 Nano-composite Solder Fabrication Process 1626.3 Microstructure 1666.4 Physical Properties 1676.5 Mechanical Properties 1696.6 Challenges and Solutions 1716.7 Summary 174Thematic Area IV: Chemical Issues Affecting Reliability 1797 Chemical Changes for Lead-Free Soldering and Their Effect on Reliability 181Laura J. Turbini7.1 Introduction 1817.2 Soldering Fluxes and Pastes 1817.3 Cleaning 1857.4 Laminates 1857.5 Halogen-Free Laminates 1867.6 Conductive Anodic Filament (CAF) Formation 1897.7 Summary 193Thematic Area V: Mechanical Issues Affecting Reliability 1958 Influence of Microstructure on Creep and High Strain Rate Fracture of Sn-Ag-Based Solder Joints 197P. Kumar, Z. Huang, I. Dutta, G. Subbarayan, and R. Mahajan8.1 Introduction 1988.2 Coarsening Kinetics: Quantitative Analysis of Microstructural Evolution 1998.3 Creep Behavior of Sn-Ag-Based Solders and the Effect of Aging 2068.4 Role of Microstructure on High Strain Rate Fracture 2198.5 Summary and Conclusions 2279 Microstructure and Thermomechanical Behavior Pb-Free Solders 233D.R. Frear9.1 Introduction 2339.2 Sn-Pb Solder 2349.3 Pb-Free Solders 2379.4 Summary 24810 Electromechanical Coupling in Sn-Rich Solder Interconnects 251Q.S. Zhu, H.Y. Liu, L. Zhang, Q.L. Zeng, Z.G. Wang, and J.K. Shang10.1 Introduction 25210.2 Experimental 25310.3 Results 25510.4 Discussion 26410.5 Conclusions 26911 Effect of Temperature-Dependent Deformation Characteristics on Thermomechanical Fatigue Reliability of Eutectic Sn-Ag Solder Joints 273Andre Lee, Deep Choudhuri, and K.N. Subramanian11.1 Introduction 27411.2 Experimental Details 27511.3 Results and Discussion 27611.4 Summary and Conclusions 294Thematic Area VI: Whisker Growth Issues Affecting Reliability 29712 Sn Whiskers: Causes, Mechanisms and Mitigation Strategies 299Nitin Jadhav and Eric Chason12.1 Introduction 29912.2 Features of Whisker Formation 30312.3 Understanding the Relationship between IMC Growth, Stress and Whisker Formation 30812.4 Summary Picture of Whisker Formation 31412.5 Strategies to Mitigate Whisker Formation 31612.6 Conclusion 31813 Tin Whiskers 323Katsuaki Suganuma13.1 Low Melting Point Metals and Whisker Formation 32313.2 Room-Temperature Tin Whiskers on Copper Substrate 32513.3 Thermal-Cycling Whiskers on 42 Alloy/Ceramics 32613.4 Oxidation/Corrosion Whiskers 32913.5 Mechanical-Compression Whiskers in Connectors 33013.6 Electromigration Whiskers 33113.7 Whisker Mitigation 33213.8 Future Work 334Thematic Area VII: Electromigration Issues Affecting Reliability 33714 Electromigration Reliability of Pb-Free Solder Joints 339Seung-Hyun Chae, Yiwei Wang, and Paul S. Ho14.1 Introduction 33914.2 Failure Mechanisms of Solder Joints by Forced Atomic Migration 34214.3 IMC Growth 35114.4 Effect of Sn Grain Structure on EM Reliability 36314.5 Summary 36615 Electromigration in Pb-Free Solder Joints in Electronic Packaging 375Chih Chen, Shih-Wei Liang, Yuan-Wei Chang, Hsiang-Yao Hsiao, Jung Kyu Han, and K.N. Tu15.1 Introduction 37615.2 Unique Features for EM in Flip-Chip Pb-Free Solder Joints 37615.3 Changes of Physical Properties of Solder Bumps During EM 38615.4 Challenges for Understanding EM in Pb-Free Solder Microbumps 39315.5 Thermomigration of Cu and Ni in Pb-Free Solder Microbumps 39415.6 Summary 39416 Effects of Electromigration on Electronic Solder Joints 401Sinn-wen Chen, Chih-ming Chen, Chao-hong Wang, and Chia-ming Hsu16.1 Introduction 40116.2 Effects of Electromigration on Solders 40216.3 Effects of Electromigration on Interfacial Reactions 40816.4 Modeling Description of Effects of Electromigration on IMC Growth 41416.5 Conclusions 418Thematic Area VIII: Thermomigration Issues Affecting Reliability 42317 Thermomigration in SnPb and Pb-Free Flip-Chip Solder Joints 425Tian Tian, K.N. Tu, Hsiao-Yun Chen, Hsiang-Yao Hsiao, and Chih Chen17.1 Introduction 42517.2 Thermomigration in SnPb Flip-Chip Solder Joints 42717.3 Thermomigration in Pb-Free Flip-Chip Solder Joints 43217.4 Driving Force of Thermomigration 43517.5 Coupling between Thermomigration and Creep 43917.6 Coupling between Thermomigration and Electromigration: Thermoelectric Effect on Electromigration 44117.7 Summary 441Thematic Area IX: Miniaturization Issues Affecting Reliability 44318 Influence of Miniaturization on Mechanical Reliability of Lead-Free Solder Interconnects 445Golta Khatibi, Herbert Ipser, Martin Lederer, and Brigitte Weiss18.1 Introduction 44518.2 Effect of Miniaturization on Static Properties of Solder Joints (Tensile and Shear) 44818.3 Creep and Relaxation of Solder Joints 47518.4 Summary and Conclusions 478References 482Index 487