Surface modification of spherical silica micro‐powder using silane coupling agents and their application in epoxy resin‐based composite materials

Abstract In recent years, the packaging industry has utilized electronic packaging materials with epoxy resin (EP) and high‐performance fillers, exhibiting superior mechanical properties and thermal conductivity. Spherical silica micro‐powder (SSP) is a critical thermal conductive filler but faces challenges due to its inorganic nature. Surface modification is essential to improve SSP's compatibility and dispersion in organic matrices for effective use in EP‐based composites. In this paper, the effects of the following four modification methods on SSP/EP composites were studied: (1) the processes include co‐modification with dimethyldimethoxysilane (DMDMS) and trimethylethoxysilane (MTES), (2) modification with NaOH, (3) co‐modification with DMDMS and MTES in an alkaline environment after NaOH modification, and (4) co‐modification with methyltrimethoxysilane (MTMS) and propyltrimethoxysilane (PTMOS). Through comprehensive characterization and evaluation, it is evident that modification schemes 1, 3, and 4 significantly enhance SSP's hydrophobicity, dispersibility, and compatibility with EP. This led to the improvement of thermal conductivity and stability of the composite, and modification scheme 4 showed the highest enhancement, with a 42.6% increase in thermal conductivity. Moreover, the mechanical properties of modified composite materials, such as bending strength, impact resistance, and tensile strength, surpass those of unmodified SSP/EP composite materials. The study provides valuable insights for reducing manufacturing costs and enhancing productivity in the electronic packaging sector.