Inkjet Technology for Digital Fabrication

About the Editors xiii

List of Contributors xv

Preface xvii

1. Introduction to Inkjet Printing for Manufacturing 1
Ian M. Hutchings and Graham D. Martin

1.1 Introduction 1

1.2 Materials and Their Deposition by Inkjet Printing 3

1.2.1 General Remarks 3

1.2.2 Deposition of Metals 3

1.2.3 Deposition of Ceramics 6

1.2.4 Deposition of Polymers 7

1.3 Applications to Manufacturing 8

1.3.1 Direct Deposition 9

1.3.2 Inkjet Mask Printing 12

1.3.3 Inkjet Etching 13

1.3.4 Inverse Inkjet Printing 14

1.3.5 Printing onto a Powder Bed 15

1.4 Potential and Limitations 15

References 17

2. Fundamentals of Inkjet Technology 21
Graham D. Martin and Ian M. Hutchings

2.1 Introduction 21

2.2 Surface Tension and Viscosity 23

2.3 Dimensionless Groups in Inkjet Printing 25

2.4 Methods of Drop Generation 27

2.4.1 Continuous Inkjet (CIJ) 27

2.4.2 Drop-on-Demand (DOD) 28

2.4.3 Electrospray 33

2.5 Resolution and Print Quality 34

2.6 Grey-Scale Printing 35

2.7 Reliability 36

2.8 Satellite Drops 38

2.9 Print-Head and Substrate Motion 39

2.10 Inkjet Complexity 42

References 42

3. Dynamics of Piezoelectric Print-Heads 45
J. Frits Dijksman and Anke Pierik

3.1 Introduction 45

3.2 Basic Designs of Piezo-Driven Print-Heads 47

3.3 Basic Dynamics of a Piezo-Driven Inkjet Print-Head (Single-Degree-of-Freedom Analysis) 49

3.4 Design Considerations for Droplet Emission from Piezo-Driven Print-Heads 60

3.4.1 Droplet Formation 60

3.4.2 Damping 66

3.4.3 Refilling 67

3.4.4 Deceleration Due to Elongational Effects Prior to Pinching Off 70

3.4.5 Summary 71

3.5 Multi-Cavity Helmholtz Resonator Theory 71

3.6 Long Duct Theory 77

3.7 Concluding Remarks 83

References 84

4. Fluids for Inkjet Printing 87
Stephen G. Yeates, Desheng Xu, Marie-Beatrice Madec, Dolores Caras-Quintero, Khalid A. Alamry, Andromachi Malandraki and Veronica Sanchez-Romaguera

4.1 Introduction 87

4.2 Print-Head Considerations 88

4.2.1 Continuous Inkjet (CIJ) 88

4.2.2 Thermal Inkjet (TIJ) 88

4.2.3 Piezoelectric Drop-on-Demand (Piezo-DOD) 89

4.3 Physical Considerations in DOD Droplet Formation 89

4.4 Ink Design Considerations 95

4.5 Ink Classification 95

4.5.1 Aqueous Ink Technology 96

4.5.2 Non-aqueous Ink Technologies 100

4.6 Applications in Electronic Devices 105

4.6.1 Organic Conducting Polymers 105

4.6.2 Conjugated Organic Semiconductors 106

4.6.3 Inorganic Particles 107

References 108

5. When the Drop Hits the Substrate 113
Jonathan Stringer and Brian Derby

5.1 Introduction 113

5.2 Stable Droplet Deposition 114

5.2.1 Deposition Maps 114

5.2.2 Impact of Millimetre-Size Droplets 116

5.2.3 Impact of Inkjet-Sized Droplets 119

5.3 Unstable Droplet Deposition 120

5.4 Capillarity-Driven Spreading 122

5.4.1 DropletSubstrate Equilibrium 122

5.4.2 Capillarity-Driven Contact Line Motion 124

5.4.3 Contact Angle Hysteresis 125

5.5 Coalescence 126

5.5.1 Stages of Coalescence 126

5.5.2 Coalescence and Pattern Formation 128

5.5.3 Stable Bead Formation 128

5.5.4 Unstable Bead Formation 130

5.6 Phase Change 131

5.6.1 Solidification 132

5.6.2 Evaporation 132

5.7 Summary 134

References 135

6. Manufacturing of Micro-Electro-Mechanical Systems (MEMS) 141
David B. Wallace

6.1 Introduction 141

6.2 Limitations and Opportunities in MEMS Fabrication 142

6.3 Benefits of Inkjet in MEMS Fabrication 143

6.4 Chemical Sensors 144

6.5 Optical MEMS Devices 147

6.6 Bio-MEMS Devices 151

6.7 Assembly and Packaging 152

6.8 Conclusions 156

Acknowledgements 156

References 156

7. Conductive Tracks and Passive Electronics 159
Jake Reder

7.1 Introduction 159

7.2 Vision 159

7.3 Drivers 160

7.3.1 Efficient Use of Raw Materials 160

7.3.2 Short-Run and Single-Example Production 161

7.3.3 Capital Equipment 162

7.4 Incumbent Technologies 162

7.5 Conductive Tracks and Contacts 162

7.5.1 What Is Conductivity? 162

7.5.2 Conductive Tracks in the Third Dimension 163

7.5.3 Contacts 163

7.6 Raw Materials: Ink 164

7.6.1 Particles 164

7.6.2 Dispersants 168

7.6.3 Carriers (Liquid Media) 170

7.6.4 Other Additives 170

7.7 Raw Materials: Conductive Polymers 172

7.8 Raw Materials: Substrates 172

7.9 Printing Processes 174

7.10 Post Deposition Processing 174

7.10.1 Sintering 174

7.10.2 Protective Layers 175

7.11 Resistors 175

7.12 Capacitors 176

7.13 Other Passive Electronic Devices 176

7.13.1 Fuses, Circuit Breakers, and Switches 176

7.13.2 Inductors and Transformers 177

7.13.3 Batteries 177

7.13.4 Passive Filters 177

7.13.5 Electrostatic Discharge (ESD) 177

7.13.6 Thermal Management 178

7.14 Outlook 178

References 178

8. Printed Circuit Board Fabrication 183
Neil Chilton

8.1 Introduction 183

8.2 What Is a PCB? 183

8.3 How Is a PCB Manufactured Conventionally? 185

8.4 Imaging 185

8.4.1 Imaging Using Phototools 187

8.4.2 Laser Direct Imaging 188

8.5 PCB Design Formats 188

8.6 Inkjet Applications in PCB Manufacturing 189

8.6.1 Introduction 189

8.6.2 Legend Printing 190

8.6.3 Soldermask 194

8.6.4 Etch Resist 195

8.7 Future Possibilities 202

References 205

9. Active Electronics 207
Madhusudan Singh, Hanna M. Haverinen, Yuka Yoshioka and Ghassan E. Jabbour

9.1 Introduction 207

9.2 Applications of Inkjet Printing to Active Devices 211

9.2.1 OLEDs 211

9.2.2 Other Displays 213

9.2.3 Energy Storage Using Batteries and Supercapacitors 214

9.2.4 Photovoltaics 215

9.2.5 Sensors 217

9.2.6 Transistors, Logic, and Memory 219

9.2.7 Contacts and Conductors 221

9.2.8 In Situ Synthesis and Patterning 223

9.2.9 Biological Applications 223

9.3 Future Outlook 224

References 225

10. Flat Panel Organic Light-Emitting Diode (OLED) Displays: A Case Study 237
Julian Carter, Mark Crankshaw and Sungjune Jung

10.1 Introduction 237

10.2 Development of Inkjet Printing for OLED Displays 238

10.3 Inkjet Requirements for OLED Applications 241

10.3.1 Introduction 241

10.3.2 Display Geometry 241

10.3.3 Containment and Solid Content 241

10.4 Ink Formulation and Process Control 243

10.5 Print Defects and Control 246

10.6 Conclusions and Outlook 249

Acknowledgements 250

References 250

11. Radiofrequency Identification (RFID) Manufacturing: A Case Study 255
Vivek Subramanian

11.1 Introduction 255

11.2 Conventional RFID Technology 256

11.2.1 Introduction 256

11.2.2 RFID Standards and Classifications 256

11.2.3 RFID Using Silicon 258

11.3 Applications of Printing to RFID 260

11.4 Printed Antenna Structures for RFID 260

11.4.1 The Case for Printed Antennae 260

11.4.2 Printed RFID Antenna Technology 261

11.4.3 Summary of Status and Outlook for Printed Antennae 262

11.5 Printed RFID Tags 263

11.5.1 Introduction 263

11.5.2 Topology and Architecture of Printed RFID 264

11.5.3 Devices for Printed RFID 267

11.6 Conclusions 273

References 273

12. Biopolymers and Cells 275
Paul Calvert and Thomas Boland

12.1 Introduction 275

12.2 Printers for Biopolymers and Cells 277

12.2.1 Printer Types 277

12.2.2 Piezoelectric Print-Heads 277

12.2.3 Thermal Inkjet Print-Heads 279

12.2.4 Comparison of Thermal and Piezoelectric Inkjet for Biopolymer Printing 279

12.2.5 Other Droplet Printers 280

12.2.6 Rapid Prototyping and Inkjet Printing 281

12.3 Ink Formulation 282

12.3.1 Introduction 282

12.3.2 Printed Resolution 283

12.3.3 Major Parameters: Viscosity and Surface Tension 283

12.3.4 Drying 285

12.3.5 Corrosion 285

12.3.6 Nanoparticle Inks 285

12.3.7 Biopolymer Inks 285

12.4 Printing Cells 289

12.4.1 Cell-Directing Patterns 289

12.4.2 Cell-Containing Inks 289

12.4.3 Effects of Piezoelectric and Thermal Print-Heads on Cells 290

12.4.4 Cell Attachment and Growth 291

12.4.5 Biocompatibility in the Body 292

12.5 Reactive Inks 292

12.6 Substrates for Printing 296

12.7 Applications 297

12.7.1 Tissue Engineering 297

12.7.2 Bioreactors 298

12.7.3 Printed Tissues 298

12.8 Conclusions 299

References 299

13. Tissue Engineering: A Case Study 307
Makoto Nakamura

13.1 Introduction 307

13.1.1 Tissue Engineering and Regenerative Medicine 307

13.1.2 The Third Dimension in Tissue Engineering and Regenerative Medicine 308

13.1.3 The Current Approach for Manufacturing 3D Tissues 309

13.1.4 A New Approach of Direct 3D Fabrication with Live Cell Printing 309

13.2 A Feasibility Study of Live Cell Printing by Inkjet 310

13.3 3D Biofabrication by Gelation of Inkjet Droplets 313

13.4 2D and 3D Biofabrication by a 3D Bioprinter 314

13.4.1 Micro-Gel Beads 314

13.4.2 Micro-Gel Fiber and Cell Printing 315

13.4.3 2D and 3D Fabrication of Gel Sheets and Gel Mesh 316

13.4.4 Fabrication of 3D Gel Tubes 316

13.4.5 Multicolor 3D Biofabrication 316

13.4.6 Viscosity in Inkjet 3D Biofabrication 318

13.5 Use of Inkjet Technology for 3D Tissue Manufacturing 319

13.5.1 Resolution and DOD Color Printing 319

13.5.2 Direct Printing of Live Cells 319

13.5.3 High-Speed Printing 319

13.5.4 3D Fabrication Using Hydrogels 320

13.5.5 Linkage to Digital Data Sources 321

13.5.6 Applicability to Various Materials including Humoral Factors and Nanomaterials 321

13.5.7 Use of Pluripotent Stem Cells in Bioprinting 322

13.6 Summary and Future Prospects 322

Acknowledgements 323

References 323

14. Three-Dimensional Digital Fabrication 325
Bill ONeill

14.1 Introduction 325

14.2 Background to Digital Fabrication 326

14.3 Digital Fabrication and Jetted Material Delivery 329

14.4 Liquid-Based Fabrication Techniques 330

14.4.1 PolyJet: Objet Geometries 330

14.4.2 ProJet: 3D Systems 333

14.4.3 Solidscape 3D Printers 333

14.5 Powder-Based Fabrication Techniques 335

14.5.1 ZPrinter: Z Corporation 335

14.5.2 Other Powder-Based 3D Printers 338

14.6 Research Challenges 338

14.7 Future Trends 340

References 341

15. Current Inkjet Technology and Future Directions 343
Mike Willis

15.1 The Inkjet Print-Head as a Delivery Device 343

15.2 Limitations of Inkjet Technology 344

15.2.1 Jetting Fluid Constraints 344

15.2.2 Control of Drop Volume 345

15.2.3 Variations in Drop Volume 345

15.2.4 Jet Directionality and Drop Placement Errors 345

15.2.5 Aerodynamic Effects 347

15.2.6 Impact and Surface Wetting Effects 348

15.3 Todays Dominant Technologies and Limitations 348

15.3.1 Thermal DOD Inkjet 348

15.3.2 Piezoelectric DOD Inkjet 350

15.4 Other Current Technologies 351

15.4.1 Continuous Inkjet 351

15.4.2 Electrostatic DOD 351

15.4.3 Acoustic Drop Ejection 352

15.5 Emerging Technologies 353

15.5.1 Stream 353

15.5.2 Mems 354

15.5.3 Flextensional 356

15.5.4 Tonejet 356

15.6 Future Trends for Print-Head Manufacturing 357

15.7 Future Requirements and Directions 358

15.7.1 Customisation of Print-Heads for Digital Fabrication 358

15.7.2 Reduce Sensitivity of Jetting to Ink Characteristics 359

15.7.3 Higher Viscosities 359

15.7.4 Higher Stability and Reliability 360

15.7.5 Drop Volume Requirements 360

15.7.6 Lower Costs 361

15.8 Summary of Status of Inkjet Technology for Digital Fabrication 361

References 362

Index 363