The investigation of interface effect on the properties of nanosilica-based underfill

We investigated three silane coupling agents for the surface modification of nanosilica and prepared silica/epoxy based underfill materials. Epoxy silane and amino silane with one primary amine group and one secondary amine group in the propyl position in both linear form and cyclic form were tested. Our first intention was that two amine groups would form a denser network, however, the amine groups react with anhydride and epoxy resin and lead to the decreased cross-linking of the resin itself. The glass transition temperature of amino silane treated silica filled composites was surprisingly low and the CTE and mechanical properties were damaged as well. A second layer of anhydride after the silica was treated with diaza silane was demonstrated to mitigate this effect.