thermosonically

… rinsing said passivated copper tape; bonding a semiconductor device to said tape; and thermosonically bonding gold wires between said tape and said semiconductor device.

1989 January 24, “4,800,178 METHOD OF ELECTROPLATING A COPPER LEAD FRAME WITH COPPER”, in OFFICIAL GAZETTE of the UNITED STATES PATENT AND TRADEMARK OFFICE, volume 1098, number 4, page 1944

We have studied the ability to thermosonically wirebond gold onto Cu/Ni/Au surface metallurgy consisting of 2 μm Cu representing the bondpad followed by 1 to 4 μm electroless Ni and 1 μm Au over 5-20 μm of BCB (CYCLOTENE™) dielectric.

2000, Richard Ulrich, Mohammed Wasef, Jang-hi Im, Phil Garrou, Dan Scheck, “WIREBONDING TO ELECTROLESSLY-METALLIZED COPPER BONDPADS OVER THICK BENZOCLOBUTENE”, in LOW AND HIGH DIELECTRIC CONSTANT MATERIALS: MATERIALS SCIENCE, PROCESSING, AND RELIABILIY ISSUES Procedings of the Fourth International Symposium and THIN FILM MATERIALS FOR ADVANCED PACKAGING TECHNOLOGIES Procedings of the Second International Symposium, The Electrochemical Society, [We have stucied the ability to thermosonically wirebond gold onto Cu/Ni/Au surface metallurgy consisting of 2 μm Cu representing the bondpad followed by 1 to 4 μm electroless Ni and 1 μm Au over 5-20 μm of BCB (CYCLOTENE™) dielectric. page 168]