Flexible Hybrid Electronics Technology Using Die-First FOWLP for High-Performance and Scalable Heterogeneous System Integration

Abstract

A technological platform is established for scalable flexible hybrid electronics (FHE) based on a novel fan-out wafer level packaging (FOWLP) methodology. Small dielets are embedded in flexible substrates we call FlexTrate TM . These dielets can be interconnected through high-density wirings formed in wafer-level processing. We demonstrate homogeneous integration of 625 (25 by 25) 1-mm-sqaure Si dielets and heterogeneous integration of GaAs and Si dielets with various thicknesses in a biocompatible polydimethylsiloxane (PDMS). In this work, 8-µm-pitch die-to-die interconnections are successfully implemented over a stress buffer layer (SBL) formed on the PDMS. In addition, coplanarity between the PDMS and embedded dielets, die shift concerned in typical die-first FOWLP, and the bendability of the resulting FlexTrate TM are characterized. Index Terms-flexible substrate, high-density interconnect, heterogeneous integration, Fan-Out Wafer-level Packaging (FOWLP), Polydimethylsiloxane (PDMS), and flexible hybrid electronics (FHE).

Layer-Scale and Chip-Scale Transfer Techniques for Functional Devices and Systems: A Review

“…Tape-assisted transfer exploits the use of commercial tapes to replace conventional PDMS stamps for chip-scale transfer [ 102 , 144 , 242 , 251 ]. Such tapes commonly have larger adhesion switchability than conventional PDMS stamps, and therefore they are well suited for high-yield pickup of the devices.…”

“…The development of flexible or wearable devices is another major factor driving the need for developing cost-effective layer transfer and chip transfer techniques [ 124 , 129 , 136 , 137 , 138 , 139 , 140 , 141 , 142 , 143 , 144 ]. Flexible electronics can find a wide range of applications, such as flexible or stretchable displays [ 137 , 145 , 146 , 147 , 148 , 149 , 150 , 151 , 152 , 153 ], flexible transistors [ 154 , 155 , 156 , 157 , 158 , 159 , 160 ], flexible solar cells [ 77 , 92 , 161 ], flexible sensors [ 162 , 163 , 164 , 165 , 166 ], wearable medical devices [ 127 , 167 , 168 , 169 ], and human–machine interfaces [ 170 , 171 , 172 , 173 , 174 ].…”

Maleimide Resin Blends with Enhanced Toughness for High-Temperature Semiconductor Packaging

“…ICs. [15][16][17][18] Because FOPs form a re-distribution layer (RDL) on the complex that molds the chip, they can provide both small and thin packaging. Furthermore, their short wiring length provides superior electrical properties.…”

Significant Die-Shift Reduction and μLED Integration Based on Die-First Fan-Out Wafer-Level Packaging for Flexible Hybrid Electronics

“…A structurally new FHE has been developed based on die-first/face-down FOWLP technology [16] with dielets using PDMS that has a low Young's modulus like a rubber and is curable at low temperature even at room temperature. The die-shift assessment has been given by UCLA [17] where the die shift is estimated to be < 6 μm.…”