Electrical Conductive Adhesives with Nanotechnologies Book

1 Introduction 1

1.1 Electronics Packaging and Interconnect 1

1.2 Interconnection Materials 11

1.2.1 Lead-Free Interconnect Materials 12

1.2.2 Electrically Conductive Adhesives 15

References 19

2 Nanotechnology 25

2.1 Introduction to Nanotechnologies and Nanopackaging 25

2.2 Nanoparticles 26

2.2.1 Introduction 26

2.2.2 Nanoparticle Fabrication 27

2.2.3 Nanoparticle Applications 28

2.3 Nano Solder Particles 30

2.4 Carbon Nanotubes (CNTs) 38

2.4.1 Carbon Nanotubes for Electrical Interconnect Applications 39

2.5 Nanocomposites 48

2.5.1 Recent Advances in Nanocomposites 48

2.5.2 Areas of Application of Nanocomposites 51

2.6 Nano Interconnect 53

2.6.1 Carbon Nanotube Transistors 53

2.6.2 CNT Via 54

2.6.3 CNT as Flip Chip Interconnect 55

2.6.4 Nanoparticle Interiayer for Copper to Copper Bonding 56

2.6.5 Nanterconnection Using Inkjet Printing of Nano-ink 56

2.7 Nanowires and Nanobelts 60

2.7.1 Introduction 60

2.7.2 Applications of Nanowires 60

References 65

3 Characterizations of Electrically Conductive Adhesives 81

3.1 Recent Advances in Polymeric Materials for Electronic Packaging 81

3.1.1 Silicones (Polyorganosiloxanes) 81

3.1.2 Epoxies 83

3.1.3 Polyurethanes 84

3.1.4 Polyimides 85

3.1.5 Silicone-Polyimide (SPI) 86

3.1.6 Bismaleimide (BMI) Resins 88

3.1.7 Cyanate Ester Resins 89

3.2 Analytical Approaches for ECA 91

3.2.1 Differential Scanning Calorimeter (DSC) 91

3.2.2 Thermogravimetry Analyzer (TGA) 95

3.2.3 Dynamic Mechanical Analyzer (DMA) 96

3.2.4 Thermo-mechanical Analysis (TMA) 98

3.2.5 Viscometer and Rheometer 100

3.2.6 Fourier Transform Infrared (FT-IR) 101

3.2.7 X-Ray Photoelectron Spectroscopy(XPS) 103

3.2.8 X-Ray Diffraction (XRD) 104

3.2.9 Transmission Electron Microscopy (TEM) 105

3.2.10 Scanning Electron Microscopy (SEM) 106

3.2.11 Raman Spectroscopy 107

3.2.12 Gas Chromatography/Mass Spectrometry 109

3.2.13 Electrical Characterization of ECAs 110

3.2.14 Mechanical Property Characterization 113

References 117

4 Isotropically Conductive Adhesives (ICAs) 121

4.1 Introduction 121

4.1.1 Percolation Theory of Conduction 121

4.1.2 Adhesive Matrix : 123

4.1.3 Conductive Fillers 124

4.2 Processing of ICAs 128

4.2.1 Screen and Stencil Printing 129

4.2.2 Dispensing 130

4.2.3 Inkjet Printing 130

4.3 Flip Chip Applications Using ICAs 132

4.3.1 ICA Process for Unbumped Chips 132

4.3.2 Metal-Bumped Flip Chip Joints 138

4.4 ICAs for Surface Mount Applications 140

4.5 ICAs for CSP Applications 141

4.6 ICAs for Advanced Packaging Applications 142

4.6.1 Solar Cell 142

4.6.2 Three-Dimensional Stacking 143

4.6.3 Microspring 144

4.7 ICAs for Printed Circuit Board Applications 146

4.8 High-Frequency Performance of ICA Joints 148

4.9 Reliability of ICA Joints 149

4.10 Recent Advances on ICAs 152

4.10.1 Fundamental Understanding of the Lubricant Layer on Ag Flakes 152

4.10.2 Understanding of Conductivity Mechanism of ICAs 166

4.10.3 Improvement of Electrical Conductivity of ICAs 176

4.10.4 Mechanism Underlying Unstable Contact Resistance of ICA Joints 178

4.10.5 Improvement of Contact Resistance Stability 189

4.10.6 Impact Performance 200

4.10.7 Adhesion Strength 202

4.10.8 Recent Advances on Nano-ICAs 205

References 211

5 An isotropically Conductive Adhesives/Films (ACA/ACF) 227

5.1 Introduction 227

5.2 ACA Materials and Processing 228

5.2.1 ACA Materials 228

5.2.2 Processing 229

5.3 Applications of ACA/ACF 231

5.3.1 ACAs/ACFs for Flat Panel Displays 231

5.3.2 ACAs/ACFs for Fine-Pitch Interconnections 234

5.3.3 ACA/ACF in Flip Chip Applications 235

5.4 Recent Advances of ACA/ACF and Nano-ACA/ACF 237

5.4.1 Low-Temperature Sintering of Nano-Ag- Filled ACA/ACF 238

5.4.2 ACA Joints with Low Melting Point (LMP) Filler 242

5.4.3 Self-Assembled Molecular Wires for Nano-ACA/ACF 244

5.4.4 Silver Migration Control in Nano-silver filled ACA 250

5.4.5 ACA/ACF with Ferromagnetic Conductive Fillers 255

5.4.6 Nanowire ACF for Ultra-fine-pitch Flip Chip Interconnection 259

5.4.7 Thermal Performance of ACA/ACF 260

5.5 ACA/ACF Reliability 263

5.5.1 Effects of Bonding Conditions 264

5.5.2 Effect of Mechanical Properties on the Reliability of ACF Joints 264

5.5.3 Effects of Bump Height on the Reliability of ACA Joints 267

5.6 Future Advances of ACA/ACF 268

5.6.1 Materials Development 268

5.6.2 High-Frequency Compatibility 268

5.6.3 Reliability 269

5.6.4 Wafer-Level Application 269

References 271

6 Non-conductive Adhesives/Films (NCA/NCF) 279

6.1 Introduction 279

6.2 Electrical Properties of NCA/NCF Joints 281

6.2.1 Contact Resistance of NCA/NCF Joints 281

6.3 Reliability of NCA/NCF Joints 285

6.4 Recent Advances of NCA/NCF 288

6.4.1 Low-Temperature Assembly of NCF 288

6.4.2 Improvement of Electrical Properties of NCA/NCF Joints with π-Conjugated Molecular Wires 289

6.4.3 NCA/NCF with Fillers 291

6.4.4 Incorporation of Non-conductive Fillers in NCA/NCF 293

6.4.5 Multi-layer ACF/NCF 294

6.4.6 Wafer-Level NCF 296

References 297

7 Conductive Nano-Inks 303

7.1 Introduction 303

7.1.1 An Overview of Conventional Patterning of Electronics 303

7.1.2 Introduction of Printed Electronics 305

7.1.3 Utility of High Volume Printing Processes in Printable Electronics 307

7.2 Conventional Conductive Inks 312

7.2.1 Metallic Ink 313

7.2.2 Conductive Carbon Ink 317

7.3 Conductive Nano-Inks 322

7.3.1 Metallic Nano-Inks 322

7.3.2 Conducting Polymer - Based Inks 326

7.3.3 Organometallic Ink 328

7.4 Processing of Nano Ink 332

7.4.1 Ink-jet Printing 332

7.4.2 Pyrolytic Printing 338

7.4.3 Gravure Printing 341

7.5 Applications of Conductive Inks 343

7.5.1 Die Attach for High Power Devices 343

7.5.2 Printed Low-resistance Metal Conductors for Printed Electronics 344

7.5.3 Micro-bump 347

7.5.4 Interconnect for System-in-Package (SiP) 349

References 351

8 Intrinsically Conducting Polymers (ICPs) 361

8.1 Basics of Intrinsically Conducting Polymers 361

8.1.1 Introduction 361

8.1.2 Doping 365

8.1.3 Polyacetylene 368

8.2 Applications of Conducting Polymers 369

8.2.1 Lithography 369

8.3 Metallization 376

8.4 Corrosion Protection of Metals 378

8.5 Electrostatic Discharge (ESD) Protection for Electronic Components 380

8.6 Field-Effect Transistors (FET) 381

8.7 Sensors 383

8.8 Microfluid Pump 390

8.9 Shielding of Electromagnetic Interference (EMI) 392

8.10 Nanofiber-Based Nanocomposites And Devices 393

8.11 Polymer Light-Emitting Diodes (PLEDs) 396

8.12 Solar Cells 402

8.13 Three-Dimensional Interconnect 404

8.14 Conducting Polymer Artificial Muscles 405

8.15 ICP as Interconnect Materials 406

References 409

9 Future Trend of Conductive Adhesive Technology 425

9.1 Recent Advances in Conductive Adhesive Technology 425

9.2 Challenges and Opportunities of ICAs 426

9.2.1 Electrical Performance Improvement 426

9.2.2 Silver Migration 426

9.2.3 Mechanical Property Improvement 427

9.2.4 Manufacturability and Yields 427

9.2.5 Cost Reduction 427

9.2.6 ICAs Based on Intrinsically Conducting Polymers 428

9.2.7 ICAs for Printed Organic Electronics 429

9.3 Challenges and Opportunities for ACAs 430

9.3.1 Thermo-mechanical Reliability 430

9.3.2 High-Frequency Compatibility 430

9.3.3 Current-Carrying Capability 430

9.3.4 Reliability 431

9.3.5 Manufacturability 431

9.4 Challenges and Opportunities for NCAs 431

References 432

Index 433