Study on the surface modification of silica particle and its filled epoxy resin

Silica particle-filled epoxy resin is widely used in electronic packaging. In this research, the isocyanate-terminated polydimethylsiloxane (ITPDMS) was synthesized by terminal-hydroxyl polydimethylsiloxane (HTPDMS) and 2, 4-toluene diisocyanate (TDI) firstly. Then the ITPDMS was used for the surface graft modification of micro-level silica. The ITPDMS modified silica (P-SiO₂) was filled into epoxy resin for enhancing the interfacial bonding between silica and ER matrix. For comparison, the modification of silica particle with other compounds such as silane coupling agent (KH-560) and 2, 4-toluene diisocyanate and their performances of particle-filled epoxy resins were also investigated. The various modified and unmodified SiO₂ were characterized by FTIR and TG. The mechanical properties of silica filled ER were measured by universal testing machine and Dynamic mechanical analysis (DMA). The morphology of silica particle filled epoxy resin was also evaluated by scanning electron microscopy (SEM) investigation of fracture surface. The results show that SiO₂ can be grafted with ITPDMS, TDI, and KH-560 effectively and the tensile strength and bending strength of the series modified SiO₂ filled ER systems are improved obviously. Especially, the tensile strength and bending strength of P-SiO₂ filled ER systems increase by 11.68% and 11.55% than those of the original SiO₂ filled ER respectively. The glass transition temperature of P-SiO₂-filled ER system was also increased, compared with those of the original SiO₂-filled ER.