Embodiments include a mixed hybrid bonding structure comprising a composite dielectric layer, where the composite dielectric layer comprises an organic dielectric material having a plurality of inorganic filler material. One or more conductive substrate interconnect structures are within the composite dielectric layer. A die is on the composite dielectric layer, the die having one or more conductive die interconnect structures within a die dielectric material. The one or more conductive die interconnect structures are directly bonded to the one or more conductive substrate interconnect structures, and the inorganic filler material of the composite dielectric layer is bonded to the die dielectric material.