Gas-permeable and stretchable nanoscale anisotropic conductive film for room-temperature, pressure-free interconnections

Abstract

As stretchable electronics advance in functionality and application scope, interconnection technologies have become critical. Devices in wearable and soft-robotic systems require thinness, stretchability, gas permeability, and damage-free bonding conditions. Accordingly, interconnection technologies must exhibit similar properties without compromising device performance. Conventional interconnection approaches rarely satisfy these requirements simultaneously owing to constraints such as typical thickness of several micrometers, low gas permeability, and the requirement for harsh bonding conditions (heat, pressure, or ultraviolet). This study presents an ultrathin, highly stretchable, gas-permeable nanoscale anisotropic conductive film (ACF) enabling damage-free bonding. The proposed ACF consists of patterned disks of silver nanowires infiltrated with styrene-ethylene-butylene-styrene block copolymer. The resulting nanoscale film (∼300-nanometer thickness) exhibits mechanical and electrical stretchability exceeding 500% strain with a water vapor transmission rate of 1200 grams per square meter per day. A bonding process based on liquid volatilization enables conformal adhesion to uneven surfaces without heat or external pressure, allowing device-to-skin and device-to-device interconnections. Light-emitting diodes integrated with stretchable wiring (500-micrometer pitch) using the proposed ACF maintained electrical conduction and interwire insulation even under 500% strain.