coating materials for electronic applications polymers processes reliability testing

✍ Scribed by James J. Licari

• Publisher: William Andrew
• Year: 2004
• Tongue: English
• Leaves: 568
• Series: Materials and Processes for Electronic Applications
• Category: Library

✦ Synopsis

This first book in the Materials and Processes for Electronics Applications series answers questions vital to the successful design and manufacturing of electronic components, modules, and systems such as: - How can one protect electronic assemblies from prolonged high humidity, high temperatures, salt spray or other terrestrial and space environments? - What coating types can be used to protect microelectronics in military, space, automotive, or medical environments? - How can the chemistry of polymers be correlated to desirable physical and electrical properties? - How can a design engineer avoid subsequent potential failures due to corrosion, metal migration, electrical degradation, outgassing? - What are the best processes that manufacturing can use to mask, clean, prepare the surface, dispense the coating, and cure the coating? - What quality assurance and in-process tests can be used to assure reliability? - What government or industry specifications are available? - How can organic coatings be selected to meet OSHA, EPA, and other regulations? Besides a discussion of the traditional roles of coatings for moisture and environmental protection of printed circuit assemblies, this book covers dielectric coatings that provide electrical functions such as the low-dielectric-constant dielectrics used to fabricate multilayer interconnect substrates and high-frequency, high-speed circuits. Materials engineers and chemists will benefit greatly from a chapter on the chemistry and properties of the main types of polymer coatings including: Epoxies, Polyimides, Silicones, Polyurethanes, Parylene, Benzocyclobenzene and many others. For manufacturing personnel, there is an entire chapter of over a dozen processes for masking, cleaning, and surface preparation and a comprehensive review of over 20 processes for the application and curing of coatings including recent extrusion, meniscus, and curtain coating methods used in processing large panels. The pros and cons of each method are given to aid the engineer in selecting the optimum method for his/her application. As a bonus, from his own experience, the author discusses some caveats that will help reduce costs and avoid failures. Finally, the author discusses regulations of OSHA, EPA, and other government agencies which have resulted in formulation changes to meet VOC and toxicity requirements. Tables of numerous military, commercial, industry, and NASA specifications are given to help the engineer select the proper callout.

✦ Table of Contents

Front Matter......Page 1
Preface......Page 5
Acknowledgments......Page 8
Table of Contents......Page 0
Front Matter......Page 9
Preface......Page 13
Acknowledgments......Page 16
Table of Contents......Page 17
1. Functions and Requirements of Coatings for Electronic Applications......Page 26
1.1.1 Adhesion—The Basic Requirement......Page 27
1.1.2 Other Requirements......Page 29
1.2.1 Moisture Protection......Page 30
1.2.2 Corrosion Protection......Page 36
1.2.4 Permeation of Gases......Page 39
1.2.5 Handling and Abrasion Resistance......Page 40
1.2.6 Resistance to Friction......Page 41
1.2.7 Hardness......Page 43
1.2.8 Particle Shielding......Page 45
1.2.10 Resistance to Solvents and Processing Chemicals......Page 46
1.2.11 Resistance to Microorganisms......Page 47
1.3 Special Metal Protection......Page 49
1.3.1 Magnesium......Page 51
1.3.3 Aluminum......Page 52
1.3.5 Wash Primers......Page 55
1.4 Electrical Functions......Page 57
1.4.1 Resistance and Resistivity......Page 58
1.4.2 Conductance and Conductivity......Page 64
1.4.4 Dielectric Constant......Page 68
1.4.5 Dissipation Factor and Power Factor......Page 71
1.4.7 Variation of Dielectric Constant and Dissipation Factor with Degree of Cure......Page 72
1.4.8 Dielectric Strength and Breakdown Voltage......Page 75
1.4.9 Arc Resistance......Page 79
1.5 Thermal Functions......Page 80
References......Page 85
2. Chemistry and Properties of Polymer Coatings......Page 89
2.1.1 Chemistry......Page 90
2.2 Polyesters......Page 91
2.2.1 Chemistry of Unsaturated Polyesters......Page 94
2.2.2 Chemistry of Alkyd Polyesters......Page 95
2.2.3 Properties of Alkyd Coatings......Page 96
2.3.1 Chemistry......Page 98
2.3.2 Properties......Page 99
2.4 Polystyrenes......Page 103
2.5 Diallylphthalate and Other Allylic Polymers......Page 104
2.6 Epoxies......Page 105
2.6.1 Chemistry......Page 106
2.6.2 Curing......Page 109
2.6.3 Classification of Epoxy Coatings......Page 119
2.6.4 Properties......Page 120
2.7 Polyurethanes......Page 128
2.7.1 Chemistry......Page 129
2.7.2 Classifications......Page 130
2.7.3 Properties......Page 138
2.8.1 Chemistry......Page 140
2.8.2 Properties......Page 150
2.9 Polyimides......Page 166
2.9.1 Chemistry......Page 167
2.9.2 Properties......Page 172
2.10 P-Polyxylylenes (Parylenes)......Page 178
2.10.1 Chemistry......Page 179
2.10.2 Properties of Parylene Coatings......Page 181
2.11 Benzocyclobutene Cyclotene......Page 192
2.11.1 Chemistry......Page 193
2.11.2 Properties......Page 195
2.12 Fluorocarbons and Fluorinated Polymers......Page 198
2.12.1 Chemistry......Page 199
2.12.2 Properties......Page 205
2.13.1 Chemistry......Page 210
2.14 Polyaryletheretherketone Peek......Page 211
2.15 Polyamides......Page 212
2.15.1 Chemistry......Page 213
2.15.2 Properties......Page 214
2.16.2 Properties......Page 215
2.17.1 Chemistry......Page 216
References......Page 218
3. Manufacturing Technology......Page 225
3.1.1 Types of Maskants.......Page 226
3.2 Cleaning......Page 227
3.2.1 Contamination Control......Page 228
3.2.2 The Nature and Effects of Contaminants......Page 229
3.2.3 Cleaning Solvents and Methods......Page 232
3.3.2 Vacuum Baking......Page 247
3.3.5 Chemical Surface Preparation......Page 248
3.4.1 Shelf Life and Pot Life......Page 249
3.5 Application Methods......Page 250
3.5.1 Spray Coating......Page 251
3.5.4 Aerosol Spray......Page 255
3.5.5 Electrostatic Spray Coating......Page 256
3.5.7 Dip Coating......Page 259
3.5.8 Fluidized-bed Coating......Page 262
3.5.9 Electrostatic Fluidized-bed Coating......Page 263
3.5.11 Vacuum Impregnation......Page 264
3.5.13 Automatic Selective Dispensing......Page 265
3.5.15 Screen Printing......Page 267
3.5.17 Spin Coating......Page 270
3.5.18 Extrusion Coating......Page 272
3.5.19 Meniscus Coating......Page 273
3.5.20 Curtain Coating......Page 275
3.6.1 Heat Curing......Page 276
3.6.2 Moisture Curing......Page 277
3.6.3 Ultraviolet Photocuring......Page 278
3.6.4 Ultraviolet Polymerization of Gaseous Monomers......Page 282
3.6.5 Microwave Curing......Page 283
3.6.6 Electron-beam Polymerization......Page 284
3.6.7 Glow-discharge/Plasma Polymerization......Page 285
3.6.8 Gamma-Radiation Curing......Page 287
3.7.1 Cross Contamination......Page 288
3.7.3 Flammability and Toxicity......Page 289
3.7.4 Inspection......Page 290
3.7.5 Rework and Repair......Page 291
References......Page 296
4. Applications......Page 302
4.1 Conformal Coatings for Printed Wiring Assemblies (PWA) 280......Page 303
4.1.1 Conformal Coating Performance......Page 311
4.1.2 Specifications for Conformal Coatings......Page 312
4.2 Coatings for Semiconductor Single Chip and Multichip Modules......Page 316
4.2.1 Environmental Protection and Passivation......Page 317
4.2.2 Reconfiguration and Redistribution of Die Bonding Pads......Page 319
4.2.3 Semiconductor Junction Coatings and Stress Buffers......Page 321
4.3 Coatings for Discrete Passive Devices......Page 324
4.4 Multilayer Circuit Board Fabrication......Page 326
4.5 Interlayer Dielectric Coatings for Multichip Module Substrates......Page 328
4.5.1 Formation of Microvias in Dielectric Coatings......Page 334
4.5.2 Supported Microbridge Crossovers......Page 341
4.6 Polymer Waveguides......Page 344
4.7 Solder Maskants......Page 345
4.8.1 Solder Maskants for CSP and BGA......Page 346
4.8.3 Alpha-Particle Emissions......Page 347
4.9 Chip-On-Board (COB) and Glob-Top Coatings......Page 348
4.10 Particle Immobilizing Coatings and Particle Getters......Page 349
4.12 Wire and Coil Coatings......Page 351
4.12.1 Magnet Wire Classifications......Page 352
4.12.2 Magnet Wire Constructions......Page 353
4.12.3 Wire Coating Types......Page 357
4.13 Coatings for Space Applications......Page 363
4.13.1 Radiation Effects......Page 364
4.13.2 Outgassing in a Thermal-Vacuum Environment......Page 371
4.13.4 Flammability......Page 375
4.13.5 Sterilization and Decontamination......Page 376
4.14 Coatings for Automotive Applications......Page 380
4.15 Coatings for Electromagnetic Interference (EMI) Shielding and Electrostatic Discharge (ESD)......Page 381
4.16 Coatings for Medical Applications......Page 385
4.17 Tamper-Proof Coatings......Page 386
4.18.2 Photoresists......Page 387
4.19 Polymer Thick Films......Page 393
4.19.1 Polymer Thick Film Conductors......Page 394
4.19.2 Polymer Thick Film Resistors......Page 397
References......Page 403
5. Reliability Assurance and Testing......Page 410
5.2 Receiving Inspection......Page 411
5.4 Final Inspection and Test......Page 412
5.5 Reliability Prediction......Page 413
5.6.1 Visual Defects......Page 415
5.6.2 Moisture and Contaminant Effects......Page 418
5.6.3 Metal Migration......Page 425
5.7.1 Tests for Ionic Contaminants Inherent in Polymers or on Surfaces......Page 430
5.7.2 Tests for Surface Ionic Contaminants......Page 432
5.7.3 Surface Insulation Resistance (SIR)......Page 434
5.7.5 Tests for Non-ionic (Organic) Residues......Page 436
5.8.1 Accelerated Humidity-Temperature Tests......Page 438
5.8.3 Moisture and Stress Test Chips......Page 441
5.9.2 Chemical Test......Page 449
5.9.4 Surface Discontinuities......Page 451
5.10.1 Tape Pull Test......Page 453
5.10.3 Contact Fatigue Adhesion Test......Page 454
References......Page 455
6. Test Methods......Page 460
6.1.1 Viscosity......Page 462
6.1.3 Surface Tension and Contact Angle......Page 463
6.1.5 Adhesion......Page 464
6.1.6 Thickness Measurements......Page 465
6.1.7 Hardness Testing......Page 466
6.1.9 Abrasion Resistance......Page 470
6.1.10 Flexibility......Page 471
6.1.12 Moisture Vapor Permeability......Page 472
6.3 Environmental Exposure Tests......Page 473
6.3.1 Temperature and Humidity Testing......Page 476
6.3.2 Weatherability......Page 477
6.3.4 Fungus Resistance......Page 478
6.4.1 Thermal Conductivity and Test Methods......Page 479
6.4.2 Thermal Stability......Page 482
6.5 Chemical/Analytical Tests......Page 484
6.5.2 Gas Chromatography......Page 485
6.5.3 Mass Spectrometry......Page 486
6.5.5 X-ray Photoelectron Spectroscopy......Page 487
6.5.6 Acoustic Microscopy......Page 488
References......Page 489
7.1 Top-Level Performance or Requirements Specification......Page 492
7.2 Material Specifications......Page 493
7.4 Work Instructions......Page 494
7.6 Military, Space, Government, and Industry......Page 495
7.7 Specifications Relating to Organic Coatings......Page 496
Conversion Factors......Page 515
Abbreviations, Acronyms, and Symbols......Page 518
A......Page 524
B......Page 526
C......Page 527
D......Page 533
E......Page 535
F......Page 537
H......Page 540
I......Page 541
L......Page 542
M......Page 543
N......Page 546
O......Page 547
P......Page 548
R......Page 555
S......Page 557
T......Page 561
V......Page 565
W......Page 566
X......Page 567
Z......Page 568