Covalent Grafting of Functional Groups Imparts Polyimide with Improved Copper Adhesion and Electrical Insulation Performance

Advances in semiconductor materials have placed increasingly stringent demands on the reliability of packaging materials for electronic devices. However, the smooth surface of copper foils and the inherent limitations of the molecular structure of polyimide (PI) lead to poor interfacial adhesion between PI and copper foil, thereby posing significant challenges to packaging reliability. Herein, a chain-end functionalization strategy is proposed to enhance the interfacial adhesion between PI and copper foils through the covalent modification of PI with 2-aminobenzimidazole (2-AB) and 4-(trimethoxysilyl)aniline (4-TMSA). The siloxane and benzimidazole moieties in the functionalized materials synergistically form covalent bonds between molecular chain ends and the copper surface, increasing interactions at the heterogeneous interface. Simulation results reveal that the chain-end modified groups preferentially migrate toward the copper region, increasing the interaction range between the molecular segments and the copper surface. This chain-end functionalization confers a high peel strength of 0.280 N/mm, a high glass transition temperature of 381.4 °C, and a high AC breakdown strength of 345.11 kV/mm, improving the reliability of the packaging material.