This article presents an experimental study of copper coplanar waveguides fabricated on silicon substrates. The waveguides are separated from the substrate by thick layers of polyimide, and can be formed on commercial integrated circuit cores using a simple postprocessing sequence. Waveguide performance is, compared to simulations and that of aluminum control devices underlayed with silicon dioxide. The lower resistance of the copper and improved substrate isolation obtained with the low-k polyimide dielectric provide a significant performance boost compared to the controls. Distributed model parameter are provided for frequencies up to 14 GHz to support circuit applications for theses devices. (C) 2004 American Vacuum Society.