Lead-Free Electronics: iNEMI Projects Lead to Successful Manufacturing

LEAD-FREE ELECTRONICS......Page 3
CONTENTS......Page 7
Preface......Page 13
Contributors......Page 15
Introduction......Page 17
Lead-Free Assembly Project......Page 18
Alloy Group......Page 19
Process Group......Page 21
Reliability Group......Page 22
Follow-On Projects/Work......Page 23
1.1. Introduction......Page 25
1.2. Lead-Free Alloys Considered by iNEMI in 1999 as Replacements for Tin–Lead Eutectic Solder......Page 27
1.3. Fundamental Properties of Lead-Free Solder Alloys Affecting Manufacturing and Reliability......Page 32
1.4. R&D Issues Remaining in Lead-Free Solder Implementation......Page 57
1.5. Summary......Page 58
References......Page 59
2.1. Introduction......Page 63
2.2. Tin–Lead Properties and Models......Page 64
2.3. Tin–Silver Properties and Creep Data......Page 80
2.4. Tin–Silver–Copper Properties and Creep Data......Page 100
2.5. Alloy Comparisons......Page 119
2.6. General Conclusions/Recommendations......Page 120
Appendix A: Tin–Silver Creep Data......Page 123
Appendix B: Tin–Silver–Copper Creep Data......Page 131
References......Page 134
3.2. Materials......Page 141
3.3. Rheology......Page 152
3.4. Applications......Page 160
3.5. Reflow Soldering......Page 161
3.6. Microstructures of Reflowed Joints......Page 178
3.7. Challenges of Lead-Free Reflow Soldering......Page 181
References......Page 193
4.1. Introduction to Component “Lead-Free” Issues......Page 199
4.2. Moisture/Reflow Impact on Packaged Integrated Circuits......Page 200
4.3. Impact of Increased Solder Peak Reflow Temperatures on Moisture Sensitivity Level Ratings......Page 201
4.4. Impact of Increased Solder Peak Reflow Temperatures......Page 207
4.5. Observations on Profiling for the Lead-Free Reflow Processes......Page 214
4.6. IC Package Improvement Options for Better Package MSL at Higher Lead-Free Solder Reflow Temperatures......Page 216
4.7. Frequency Control Products......Page 219
4.8. “Lead-Free” Cost Impact on Components......Page 222
4.9. Packaging Identification of Lead-free Packaged ICs......Page 223
4.10. Conclusions......Page 225
References......Page 226
5.1. Introduction......Page 227
5.2. Basic Physical Properties of Solder......Page 229
5.3. Creep Deformation......Page 233
5.4. Thermal Fatigue......Page 234
5.5. Creep Rupture......Page 249
5.6. Isothermal (Mechanical) Fatigue......Page 251
5.7. Out-of-Plane Bending......Page 254
5.8. Impact/Shock Loading......Page 257
5.9. Effect of Rework on Reliability......Page 264
5.11. Electrochemical Migration......Page 265
5.13. Tin Pest......Page 266
References......Page 267
6.1. Reliability Team Goals......Page 273
6.2. Reliability Test Matrix......Page 274
6.3. Component-Paste-Board Finish Combinations......Page 275
6.4. Components......Page 276
6.5. Test Vehicles......Page 277
6.6. Pre-Test/Post-Assembly Information......Page 279
6.7. CTE Determination: Component and Boards......Page 280
6.8. Thermal Cycling Conditions......Page 281
6.9. Failure Criteria......Page 282
6.11. Failure Data, Analysis Packages......Page 283
6.12. Weibull Analyses......Page 284
6.13. Post-Cycling Failure Analysis......Page 285
6.14. Bend Testing......Page 298
6.17. Overall Summary, Conclusions......Page 300
References......Page 301
7.1. Introduction......Page 303
7.2. Mitigation Strategies......Page 306
7.3. Tin Whisker Test Development......Page 314
7.4. Summary......Page 331
References......Page 332
8.1. Introduction......Page 335
8.2. Printability of Lead-Free Solder Pastes......Page 336
8.3. Soak Versus Ramp Temperature Profiles......Page 345
8.4. Effect of Peak Temperature Versus Reflow Performance......Page 348
8.5. Effect of Reflow Atmosphere on Solderability of Lead-Free Solder......Page 358
8.6. Convection Versus IR Reflow Ovens......Page 360
8.7. Reflow Temperature Delta on Boards and Components......Page 362
8.8. Visual Inspection of Lead-Free Soldered Joints......Page 366
8.9. Automated Optical Inspection (AOI)......Page 369
8.10. X-ray Inspection of Lead-Free Soldered Joints......Page 371
8.11. Acoustic Microscopy Inspection of Components Before and After Lead-Free Reflow......Page 374
8.12. Lead-Free Rework of BGA/CSP Soldered Joints......Page 377
8.13. Lead-Free Hand-Soldering Rework......Page 383
8.14. In-Circuit Testing and Functional Testing (ICT/FT) of Soldered Joints......Page 386
8.16. Surface-Mount Fillet Lifting and Reliability of Reflowed Soldered Joints......Page 387
8.17. Conclusions......Page 392
Acknowledgments......Page 394
References......Page 395
9.1. Introduction......Page 401
9.2. Approach and Strategy......Page 402
9.3. Observations and Results......Page 404
9.4. Conclusions......Page 422
9.5. Summary......Page 425
References......Page 426
10.1. Introduction......Page 427
10.2. Are Your Products within the Scope of the EU ROHS?......Page 428
10.3. Ten Steps to ROHS Compliance......Page 431
10.4. Part Numbering Important for Differentiating Lead-Free from Tin–Lead Components and Boards......Page 436
10.5. A Standards-Based Approach to Materials Declaration......Page 440
10.6. Standards......Page 446
10.7. High-Reliability Requirements......Page 451
References......Page 455
Index......Page 457