Novel fluorobenzimidazole-assisted heat resistant anticorrosion copper surface for high-density interconnected printed circuit boards

Abstract

Self-assembled organic films of imidazole derivatives are vital for metal surface modification, but their effectiveness in the commercialization of high-density copper interconnects remains limited. To enhance thermal and chemical stability, we synthesized five fluorobenzimidazole monomers by integrating fluorine into the imidazole structure using a solvent-free method. Notably, the 5-chloro-2-(2-chloro-4-fluorobenzyl)-1H-benzo[d]imidazole (5224FIM) demonstrated an impressive inhibition efficiency of 95.00 %, forming a robust barrier approximately 4450 Å thick, which effectively withstands damage under high temperature and humidity. X-ray photoelectron spectroscopy (XPS) analysis revealed that the oxygen content in sample 5442FIM was 9.02 %, the lowest among the samples, while the nitrogen content was 8.19 %, indicating a substantial presence of imidazole molecules. In comparison to non-substituted benzimidazole films, these fluorine-enhanced self-assembled films on copper exhibited superior heat and moisture resistance. Notably, printed circuit boards coated with 5224FIM demonstrated excellent performance in 72-h salt spray and 245 °C tin immersion solderability tests, highlighting their enhanced surface protection capabilities.