ABSTRACT
According to the ASTM denition,1 AM or rapid prototyping (RP) is the process of joining materials to make objects from 3D model data, usually layer upon layer. More colloquially, AM and RP are referred to as 3D printing. In addition to layer-based AM processes, there are direct-writing techniques (DW) in which functional and/or structural materials are precisely deposited onto a substrate in digitally dened locations.2,3 DW
CONTENTS
8.1 Introduction ........................................................................................................................ 215 8.2 What Are Electronics and Why Do We Need Them in 3D Objects? .......................... 217 8.3 Conventional Fabrication of Electronics ......................................................................... 218 8.4 Printed Electronics ............................................................................................................. 220 8.5 Direct-Writing of Electronics............................................................................................222 8.6 Why Does DW Not Translate Readily to 3D Printing?.................................................223 8.7 Categories for Generating Electronics in 3D Objects ................................................... 224
8.7.1 Hybrid Chip Insertion Approach (Category 1) ..................................................225 8.7.1.1 Pick and Place ..........................................................................................225 8.7.1.2 Ultrasonic Consolidation for Embedding Electronic Structures .....225 8.7.1.3 Integrating Circuitry Using Transfer Printing ................................... 226 8.7.1.4 Laser-Assisted Transfer ..........................................................................228 8.7.1.5 Connecting the Transferred Components ........................................... 229
8.7.2 Surface DW Approach (Category 2) ....................................................................229 8.7.2.1 Droplet-Based DW ..................................................................................230 8.7.2.2 Energy Beam-Based DW ........................................................................235 8.7.2.3 Flow-Based DW .......................................................................................236
