The present disclosure relates to implantable neuromodulation devices and methods of fabrication, and in particular to a thin-film electrode assemblies and methods of fabricating the thin-film electrode assembly to include a soft overmold. Particularly, aspects of the present invention are directed to a thin-film electrode assembly that includes an overmold and a supporting structure formed within a portion of the overmold. The overmold includes a first polymer and the supporting structure includes a second polymer, different from the first polymer. The thin-film electrode assembly also includes a wire formed within a portion of the supporting structure, and an electrode formed on a top surface of the supporting structure and in electrical contact with the wire.