IC Component Sockets

WEIFENG LIU, PHD, is an Interconnect Specialist at the Business Critical Systems Organization of Hewlett Packard Company. A member of IMAPS and IEEE, he has published numerous papers and has one patent pending.MICHAEL G. PECHT, PHD, is a professional engineer and a Fellow of IEEE and ASME. He is the founder and director of the CALCE Electronic Products and Systems Center at the University of Maryland. Among the awards he has received are the 3M Research Award, the IEEE Undergraduate Teaching Award, and the IMAPS William D. Ashman Memorial Achievement Award for his contributions in the field. He has written sixteen books on electronic product development, served as chief editor of the IEEE Transactions on Reliability, and served on the Advisory Board of IEEE Spectrum.

"…thoroughly examines the arena of IC component sockets…it is highly recommended…" (E-STREAMS, May 2005)

• Preface xi1 IC Component Socket Overview 11.1 Levels of Interconnections 11.2 Component-to-Board Interconnection 21.3 Classification of Component Sockets 31.4 Structure of IC Component Sockets 41.4.1 Socket Housing 51.4.2 Socket Contact 81.4.3 Socket Actuation 81.4.4 Heat Sink 91.4.5 Socket Polarization 101.5 Socket Function 101.6 Socket Assembly 111.7 Benefits of Using IC Component Sockets 111.7.1 Component Test and Burn-in 111.7.2 Component Upgrade and Exchange 121.7.3 Flexibility in IC Design and Assembly and Supply Chain Management 131.7.4 Use of Sockets to Avoid Soldering 131.7.5 Component Replacement and Repair 141.7.6 Cost Savings 141.8 Challenges Facing IC Component Sockets 151.8.1 Extra Signal Path 151.8.2 Increased Assembly Area 151.8.3 Compatibility with Fine-Pitch Applications 151.8.4 Reliability 161.9 IC Component Socket Market 171.10 Summary and Future Directions 18References 182 Component Socket Properties 212.1 Socket Contact 212.1.1 Insertion and Extraction Force 212.1.2 Contact Retention 242.1.3 Contact Force and Resistance 252.1.4 Contact Deflection and Resistance 272.1.5 Contact Wipe 292.1.6 Current Rating 312.1.7 Capacitance and Inductance 322.1.8 Bandpass and Bandwidth 352.2 Socket Housing 372.2.1 Electrical Properties 372.2.2 Mechanical Properties 392.2.3 Temperature Rating 412.2.4 Flammability 422.3 Summary 43References 433 IC Component Socket Materials 453.1 Socket Housing 453.1.1 Polymer Fundamentals 453.1.2 Thermoplastics 473.1.3 Thermosetting Polymers 503.1.4 Additives 523.1.5 Housing Manufacturing 533.2 Socket Contact 533.2.1 Copper Alloys 543.2.2 Nickel Alloys 593.2.3 Conductive Elastomers 603.2.4 Contact Manufacturing 613.3 Socket Contact Plating 643.3.1 Noble Metal Plating 653.3.2 Non-Noble Metal Plating 693.3.3 Underplate 703.3.4 Plating Process 713.4 Summary 74References 744 Component Sockets for PTH Packages 764.1 DIP Sockets 764.1.1 DIP Socket Designs 764.1.2 Dual-Beam Contact Design 784.1.3 Single-Beam Contact Design 794.1.4 Multiple-Finger Contact Design 804.1.5 Low-Force Contact Design 814.1.6 ZIF Contact Design 814.1.7 Insertion and Extraction Tools 814.2 PGA Sockets 824.2.1 PGA Socket Designs 824.2.2 Dual-Beam Contact Design 854.2.3 Multiple-Finger Contact Design 854.2.4 Fuzz Button Contact Design 854.2.5 ZIF Contact Design 864.2.6 Insertion and Extraction Tools 864.3 Summary 87References 875 Component Sockets for J-Leaded Packages 885.1 Socket Designs 885.1.1 Single-Pinch Contact Design 895.1.2 Dual-Pinch Contact Design 905.1.3 Side-Contact Design 905.1.4 Nested-Contact Design 905.1.5 ZIF Contact Design 915.1.6 Insertion and Extraction Tools 915.2 Summary 92References 936 Component Sockets for Gull-wing Packages 946.1 Socket Designs 946.1.1 Shoulder Contact Design 946.1.2 Tip Contact Design 956.1.3 Foot Contact Design 966.1.4 Ankle Contact Design 976.1.5 Dual-Pinch Contact Design 986.1.6 Insertion and Extraction Tools 986.2 Summary 99References 997 Component Sockets for BGA Packages 1007.1 Socket Designs 1007.1.1 Solder Ball Bottom Contact Design 1027.1.2 Single-Sided Contact Design 1057.1.3 Double-Sided Contact Design 1067.1.4 Four-Point Crown Contact Design 1087.2 Summary 109References 1098 Component Sockets for LGA Packages 1108.1 LGA Socket Designs 1128.1.1 Metallic Spring Design 1148.1.2 Pogo Pin Socket Design 1238.1.3 Wire-Button Contact Design 1258.1.4 Conductive Elastomer Design 1258.2 Comparison of Contact Reliability 1348.3 Future Challenges for LGA Socket Design 1358.4 Summary 135References 1369 Failure Modes and Mechanisms 1389.1 Dry Oxidation 1409.2 Pore Corrosion 1419.3 Creep Corrosion 1429.4 Fretting Corrosion 1439.5 Galvanic Corrosion 1459.6 Stress Corrosion 1459.7 Electrochemical Migration 1459.8 Intermetallic Formation 1459.9 Stress Relaxation 1469.10 Creep 1479.11 Fracture and Fatigue 1489.12 Friction Polymerization 1489.13 Whisker Growth 1499.14 Fungus Growth 1509.15 Contact Wear 1519.16 Outgassing 1529.17 Leakage Current and Dielectric Breakdown 1529.18 Swelling 1539.19 Summary 153References 15410 Socket Testing and Qualification 15810.1 Accelerated Testing 15810.2 Environmental Classifications 16110.3 Test Conditions 16210.3.1 Preconditioning 16210.3.2 Shock and Vibration 16210.3.3 Thermal Aging 16410.3.4 Temperature Cycling 16410.3.5 Thermal Cycling with Humidity 16510.3.6 Mixed Flowing Gas Tests 16510.3.7 Particulate Tests 16810.4 Test Sequencing 17010.5 Four-Wire versus Two-Wire Measurement 17010.6 Periodic and Continuous Monitoring 17110.7 Virtual Reliability Assessment 17210.8 Socket Qualification 17310.9 Summary 174References 17411 Reliability Assessment 17611.1 Contact Resistance Theory 17611.2 Contact Reliability Theory 17911.3 Intermittences 18211.4 Socket Reliability Prediction 18311.4.1 IEEE Reliability Prediction Standard 1413 18311.4.2 Guidebook for IEEE Standard 1413 18511.5 Achieving Socket Reliability 18511.6 Summary 190References 19012 Standards and Specifications 19212.1 Standards and Specifications 19212.2 Obtaining Documents 199Appendix A Terms and Definitions 201Appendix B Socket Manufacturers 206Index 215