Fabrication of 4-Inch-Scale Stretchable Anisotropic Conductive Films via Oscillated-Rubbing-Induced Microparticle Arrangement

Stretchable anisotropic conductive films (S-ACFs) provide unidirectional electrical conduction while maintaining flexibility and stretchability, making them promising for wearable electronics and soft interconnects. Their functionality relies on precise alignment of conductive microparticles (MPs) and stable electrical pathways under deformation. In this study, we demonstrate a 4-inch-scale fabrication method for S-ACF by combining hot-embossing imprinting and oscillatory rubbing-induced MPs alignment. Large-area micro-patterned templates are fabricated by hot embossing a thermoplastic elastomer (SEBS-g-MA) near its glass-transition temperature, enabling high-fidelity replication of micro-well arrays. Subsequently, a dry mechanical rubbing process was applied with controlled normal pressure and oscillatory shear force to drive randomly distributed Au-MPs into the pre-defined wells within seconds. The optimal rubbing condition-defined by the balance between sliding and rolling forces-enabled uniform particle arrangement across the entire 4-inch area without template damage or particle loss. The resulting S-ACFs exhibited stable conductivity and mechanical durability under repeated strain. This simple and scalable dry process provides a high-throughput route for precise microparticle assembly and offers a promising platform for large-area stretchable electronic packaging.