A sandwich-structured anisotropic conductive film with robust interfacial reliability and conductivity for functional electrical interconnections

Anisotropic conductive films (ACF) are of great significance in the high-precision electrical interconnection of modern microelectronic components. However, conventional ACF exposes risks of short-circuiting and high contact resistance due to conductive particles’ random movement during application. Herein, a sandwich-structured ACF with excellent electrical conductivity and high interfacial reliability between layers is developed. The key aspect of the ACF is interfacial chemical modification, the specially designed layer is prepared by polymer compounds that have undergone chemical grafting with triethylenetetramine (TETA) molecular chains. The amination-modified polymer compound promotes an epoxy ring-opening reaction that establishes chemical bonds between the epoxy layers, improving the composite film’s bonding strength by 47.9 % and changing its failure mode from cohesive to adhesive in die-shear tests. Furthermore, ACF is prepared by adding the conductive microspheres (MPs) to the polymer layer. Due to the conductive MPs have been limited movement and arranged in a monolayer, ACF exhibits an excellent electrical conductivity of up to 26.6 S/m in the Z-direction and a high anisotropic intensity of 7.8 orders of magnitude higher than the conductivity in the X/Y-direction. Otherwise, it demonstrates an outstanding shear resistance of 15.7 MPa and robust electrical interconnections to flexible circuits under the sustained peel. Therefore, this work focuses on achieving excellent performance with a low-cost, simple preparation process that takes into account a wide range of practical applications for functional electrical connections and nanodevices in modern electronic packaging.