Electronic assemblies may be fabricated with interconnects of different types present in multiple locations and comprising fused copper nanoparticles. Each interconnect or a portion thereof comprises a bulk copper matrix formed from fusion of copper nanoparticles or a reaction product formed from copper nanoparticles. The interconnects may comprise a copper-based wire bonding assembly, a copper-based flip chip connection, a copper-based hermetic seal assembly, a copper-based connector between an IC substrate and a package substrate, a copper-based component interconnect, a copper-based interconnect comprising via copper for establishing electrical communication between opposite faces of a package substrate, a copper-based interconnect defining a heat channel formed from via copper, and any combination thereof.