Three-Dimensional Interconnect Technologies for Advanced Flexible Electronics

Flexible electronics have revolutionized wearable devices, soft robotics, and human-machine interfaces, yet conventional 2D architectures face inherent limitations in integration density and performance. 3D integration emerges as a transformative solution, enabling vertical stacking of functional layers to achieve miniaturization, improved signal integrity, and heterogeneous system integration. Despite these benefits, critical challenges remain in developing reliable 3D interconnect technologies for flexible systems, including the need for stretchable and highly conductive materials, robust fabrication processes for multilayer integration, and solutions to mitigate interfacial stress and signal crosstalk. This review systematically examines recent advancements in 3D flexible interconnects, covering material innovations, fabrication techniques, rigid-flex integration strategies, and crosstalk suppression approaches. Representative applications of 3D flexible electronics are further highlighted and future research directions are discussed to advance this promising field.