Hermeticity of Electronic Packages, Second Edition

✍ Scribed by Hal Greenhouse

• Publisher: William Andrew
• Year: 2011
• Tongue: English
• Leaves: 623
• Edition: 2
• Category: Library

✦ Synopsis

This is a book about the integrity of sealed packages to resist foreign gases and liquids penetrating the seal or an opening (crack) in the package?especially critical to the reliability and longevity of electronics. The author explains how to predict the reliability and the longevity of the packages based on leak rate measurements and the assumptions of impurities. Non-specialists in particular will benefit from the author's long involvement in the technology. Hermeticity is a subject that demands practical experience, and solving one problem does not necessarily give one the background to solve another. Thus, the book provides a ready reference to help deal with day to day issues as they arise.The book gathers in a single volume a great many issues previously available only in journals?or only in the experience of working engineers. How to define the ""goodness"" of a seal? How is that seal measured? How does the integrity of the seal affect circuit reliability? What is the significance of the measured integrity of the seal? What is the relationship of Residual Gas Analysis and the seal integrity? The handbook answers these questions and more, providing an analysis of nearly 100 problems representative of the wide variety of challenges that actually occur in industry today.

✦ Table of Contents

Cover image......Page 1
Table of Contents......Page 3
Front-matter......Page 9
Copyright......Page 11
Dedication......Page 15
Preface to the First Edition......Page 17
Preface to the Second Edition......Page 20
About the Authors......Page 23
Acknowledgments......Page 27
1. Gas Kinetics......Page 29
1.1. General Considerations......Page 31
1.2. Mathematical Relationships......Page 36
1.3. Problems and Their Solutions......Page 42
2. Viscous and Molecular Conductance of Gases......Page 48
2.1. Conduction of Gases......Page 50
2.2. Viscous Conduction......Page 53
2.3. Molecular Conduction......Page 56
2.4. Conduction in the Transitional Range......Page 63
2.5. Composite Conductance Equations......Page 64
2.6. Smallest Theoretical Leak......Page 66
2.7. Discussion......Page 73
2.8. Problems and their Solutions......Page 74
3. The Flow of Gases......Page 89
3.1. General Flow Characteristics......Page 90
3.2. Measured, Standard, and True Leak Rates......Page 94
3.3. Leak Rates for Different Gases......Page 96
3.4. Change of Partial Pressure With Time......Page 98
3.5. Viscous Flow From Sealed Packages......Page 105
3.6. Viscous Flow Rates of Different Gases......Page 113
3.7. Problems and Their Solutions......Page 118
4. The Flow of Gases into Sealed Packages......Page 134
4.1. Molecular Flow......Page 135
4.2. Oxygen Leaking Into Sealed Packages......Page 141
4.3. Viscous Flow Into and Out of Sealed Packages......Page 147
4.4. The Simultaneous Flow of Gases in Both Directions......Page 153
4.5. Problems and their Solutions......Page 165
5. Understanding Fine Leak Testing in Accordance with Method 1014, MIL-STD-883......Page 207
5.1. Purpose of the Test......Page 209
5.2. Basis of the Test......Page 210
5.3. Fixed Method of Testing......Page 214
5.4. Flexible Method of Testing......Page 220
5.5. Comparison of the Fixed and Flexible Methods......Page 223
5.6. The Effect of Viscous Flow......Page 225
5.7. Leak Rate Limits are Too Lenient......Page 228
5.8. Backfilling the Package with Helium......Page 232
5.9. Bombing after Backfilling......Page 236
5.10. Leak Rate Measurements Using Krypton-85 Tacer Gas......Page 240
5.11. Problems and their Solutions......Page 249
6. Fine Leak Measurements Using a Helium Leak Detector......Page 276
6.1. Principle of Operation......Page 277
6.2. Definitions......Page 278
6.3. Calibration Using a Standard Leak......Page 279
6.4. Measurement Errors, Not Including Background Errors......Page 282
6.5. Background Errors......Page 285
6.6. Errors Due to Helium on the External Surface of the Package......Page 287
6.7. Minimum Detectable Leak (MDL)......Page 291
6.8. Correlation of Standard Leaks......Page 294
6.9. Cumulative Helium Leak Test (CHLT)......Page 296
6.10. Locating Leaks in Packages......Page 302
6.11. Problems and their Solutions......Page 303
7. Gross Leaks......Page 323
7.1. Introduction......Page 324
7.2. Forcing a Liquid Into a Package......Page 325
7.3. Fluorocarbon Vaporexiting a Package......Page 341
7.4. The Bubble Test......Page 348
7.5. The Vapor Detection Test......Page 349
7.6. The Weight Gain Test......Page 352
7.7. Optical Leak Test......Page 353
7.8. Penetrant Dye Test......Page 370
7.9. Fluorocarbons From a Residual Gas Analysis......Page 371
7.10. Quantitative Comparison of Gross Leak Test Methods......Page 379
7.11. Problems and their Solutions......Page 380
8. The Permeation of Gases Through Solids......Page 403
8.1. Description of the Permeation Process......Page 404
8.2. Effect of Temperature on Permeation......Page 410
8.3. Treating Permeation as a Leak Rate......Page 412
8.4. Water Vapor Passing Through Plastics......Page 417
8.5. Problems and their Solutions......Page 424
9. Water in Sealed Packages......Page 431
9.1. Water Related Corrosion and Circuit Failures......Page 435
9.2. Water Leaking Into a Sealed Package From the Outside Environment......Page 444
9.3. Water Outgassing Inside the Package......Page 454
9.4. Water as a Result of a Chemical Reaction Within the Package......Page 461
9.5. Problems and their Solutions......Page 462
10. Residual Gas Analysis (RGA)......Page 503
10.1. Description of the Test......Page 504
10.2. What the Test Measures......Page 506
10.3. Calculation of Leak Rates from RGA Data......Page 509
10.4. Interpretation of RGA Data......Page 518
10.5. The Qualification of Small Packages Using RGA......Page 529
10.6. Problems and their Solutions......Page 533
11. Residual Gas Analysis (RGA) and Failure Modes......Page 543
11.1. History and Background – Moisture in Sealed Microelectronic Devices......Page 548
11.2. Volatiles Other Than Moisture......Page 552
11.3. Mass Spectrometry for Package Gas Analysis......Page 554
11.4. Interpreting Gas Analysis Reports......Page 560
11.5. Headspace Gas Compositions......Page 561
11.6. Confusing Test Results......Page 569
11.7. Moisture Compliance and Hermeticity......Page 573
11.8. Conclusion......Page 579
11.9. Problems and their Solutions......Page 580
Appendix......Page 589
Index......Page 601