Lead-Free Electronics iNEMI Projects Lead to Successful Manufacturing

by Bradley, Edwin; Handwerker, Carol A.; Bath, Jasbir; Parker, Richard D.; Gedney, Ronald W.

• ISBN13: 9780471448877
• ISBN10: 0471448877
• Edition: 1st
• Format: Hardcover
• Copyright: 2007-10-12
• Publisher: Wiley-IEEE Press

Summary

Based on the results of a more than two-year study, Lead-Free Electronics: iNEMI Projects Lead to Successful Manufacturing is the first practical, primary reference to cover Pb-free solder assembly as well as the analysis and reasoning behind the selection of Sn-Ag-Cu as the recommended Pb-free replacement for Sn-Pb. Reflecting the results of a two-year study, Lead-Free Electronics: iNEMI Projects Lead to Successful Manufacturing provides full coverage of the issues surrounding the implementation of Pb-free solder into electronic board assembly. This book is extremely timelyamost electronic manufacturers are going to change over to Pb free soldering by 2006 to meet new European laws. All manufacturers around the globe are going to be affected by this change. The text provides specific results from the thirty company NEMI project activities. It contains integrated and fully documented book chapters with references to existing published work in the area. These serve as tremendous resources for engineers and companies faced with making the switch to Pb-free solder assembly.

Author Biography

Edwin Bradley is a Distinguished Member of the Technical Staff with Motorola Advanced Product Technology Center in Plantation, Florida. He has extensive experience evaluating the materials, assembly processes, and reliability of portable electronic products, with an emphasis on lead-free soldering.

Carol A. Handwerker is Professor of Materials Engineering at Purdue University. She is active on the iNEMI Technical and Research Committees.

Jasbir Bath is Lead Process Engineer at Solectron Technical Centre in Milpitas, California. He has been chair of various iNEMI lead-free consortia groups.

Richard D. Parker has spent nearly forty years at Delphi Electronics & Safety in Kokomo, Indiana, and he has been active in iNEMI since its inception.

Ronald W. Gedney retired as vice president of operations at iNEMI and remains on as a consultant. A Fellow of the IEEE, he is also a past president of the IEEE Components, Packaging, and Manufacturing Technology (CPMT) Society.

Table of Contents

Preface	p. xi
Contributors	p. xiii
Introduction	p. 1
Lead-Free Assembly Project	p. 2
Alloy Group	p. 3
Process Group	p. 5
Component Group	p. 6
Reliability Group	p. 6
Follow-On Projects/Work	p. 7
Alloy Selection	p. 9
Introduction	p. 9
Lead-Free Alloys Considered by iNEMI in 1999 as Replacements for Tin-Lead Eutectic Solder	p. 11
Fundamental Properties of Lead-Free Solder Alloys Affecting Manufacturing and Reliability	p. 16
R&D Issues Remaining in Lead-Free Solder Implementation	p. 41
Summary	p. 42
References	p. 43
Review and Analysis of Lead-Free Solder Material Properties	p. 47
Introduction	p. 47
Tin-Lead Properties and Models	p. 48
Tin-Silver Properties and Creep Data	p. 64
Tin-Silver-Copper Properties and Creep Data	p. 84
Alloy Comparisons	p. 103
General Conclusions/Recommendations	p. 104
Tin-Silver Creep Data	p. 107
Tin-Silver-Copper Creep Data	p. 115
Acknowledgments	p. 118
References	p. 118
Lead-Free Solder Paste Technology	p. 125
Introduction	p. 125
Materials	p. 126
Rheology	p. 136
Applications	p. 144
Reflow Soldering	p. 145
Microstructures of Reflowed Joints	p. 162
Challenges of Lead-Free Reflow Soldering	p. 165
Summary	p. 177
References	p. 177
Impact of Elevated Reflow Temperatures on Component Performance	p. 183
Introduction to Component "Lead-Free" Issues	p. 183
Moisture/Reflow Impact on Packaged Integrated Circuits	p. 184
Impact of Increased Solder Peak Reflow Temperatures on Moisture Sensitivity Level Ratings	p. 185
Impact of Increased Solder Peak Reflow Temperatures	p. 191
Observations on Profiling for the Lead-Free Reflow Processes	p. 198
IC Package Improvement Options for Better Package MSL at Higher Lead-Free Solder Reflow Temperatures	p. 200
Frequency Control Products	p. 203
"Lead-Free" Cost Impact on Components	p. 206
Packaging Identification of Lead-free Packaged ICs	p. 207
Conclusions	p. 209
Acknowledgments	p. 210
References	p. 210
Lead-Free Assembly Reliability-General	p. 211
Introduction	p. 211
Basic Physical Properties of Solder	p. 213
Creep Deformation	p. 217
Thermal Fatigue	p. 218
Creep Rupture	p. 233
Isothermal (Mechanical) Fatigue	p. 235
Out-of-Plane Bending	p. 238
Impact/Shock Loading	p. 241
Effect of Rework on Reliability	p. 248
High-Temperature Operating Life (HTOL)	p. 249
Electrochemical Migration	p. 249
Tin Whiskering	p. 250
Tin Pest	p. 250
Summary	p. 251
Acknowledgments	p. 251
References	p. 251
Lead-Free Assembly Reliability: iNEMI Evaluation and Results	p. 257
Reliability Team Goals	p. 257
Reliability Test Matrix	p. 258
Component-Paste-Board Finish Combinations	p. 259
Components	p. 260
Test Vehicles	p. 261
Pre-Test/Post-Assembly Information	p. 263
CTE Determination: Component and Boards	p. 264
Thermal Cycling Conditions	p. 265
Failure Criteria	p. 266
Thermal Cycle Relative Performance	p. 267
Failure Data, Analysis Packages	p. 267
Weibull Analyses	p. 268
Post-Cycling Failure Analysis	p. 269
Bend Testing	p. 282
Electrochemical Migration Testing [36, 37]	p. 284
iNEMI Team Conclusions	p. 284
Overall Summary, Conclusions	p. 284
ASTM Test Methods	p. 285
References	p. 285
Tin Whiskers: Mitigation Strategies and Testing	p. 287
Introduction	p. 287
Mitigation Strategies	p. 290
Tin Whisker Test Development	p. 298
Summary	p. 315
Acknowledgments	p. 316
References	p. 316
Lead-Free Reflow and Rework	p. 319
Introduction	p. 319
Printability of Lead-Free Solder Pastes	p. 320
Soak Versus Ramp Temperature Profiles	p. 329
Effect of Peak Temperature Versus Reflow Performance	p. 332
Effect of Reflow Atmosphere on Solderability of Lead-Free Solder	p. 342
Convection Versus IR Reflow Ovens	p. 344
Reflow Temperature Delta on Boards and Components	p. 346
Visual Inspection of Lead-Free Soldered Joints	p. 350
Automated Optical Inspection (AOI)	p. 353
X-ray Inspection of Lead-Free Soldered Joints	p. 355
Acoustic Microscopy Inspection of Components Before and After Lead-Free Reflow	p. 358
Lead-Free Rework of BGA/CSP Soldered Joints	p. 361
Lead-Free Hand-Soldering Rework	p. 367
In-Circuit Testing and Functional Testing (ICT/FT) of Soldered Joints	p. 370
Yield Data	p. 371
Surface-Mount Fillet Lifting and Reliability of Reflowed Soldered Joints	p. 371
Conclusions	p. 376
Future Work	p. 378
Acknowledgments	p. 378
References	p. 379
Case Study: Pb-Free Assembly, Rework, and Reliability Analysis of IPC Class 2 Assemblies	p. 385
Introduction	p. 385
Approach and Strategy	p. 386
Observations and Results	p. 388
Conclusions	p. 406
Summary	p. 409
Acknowledgments	p. 410
References	p. 410
Implementing RoHS and WEEE-Compliant Products	p. 411
Introduction	p. 411
Are Your Products within the Scope of the EU RoHS?	p. 412
Ten Steps to RoHS Compliance	p. 415
Part Numbering Important for Differentiating Lead-Free from Tin-Lead Components and Boards	p. 420
A Standards-Based Approach to Materials Declaration	p. 424
Standards	p. 430
High-Reliability Requirements	p. 435
Business Impact of Supply Chain Conversion	p. 439
Summary	p. 439
References	p. 439
Index	p. 441
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