Electro-plated gold films are used extensively in packaging of MEM sensors to make connections to signal conditioning electronics. Over the past two years, production lots of gold plated substrates, procured from various vendors, failed an accelerated aging qualification test. In this test, 0.0025 [mm] diameter aluminum wires were ultrasonically welded to the film, aged at 120°C for 48 hours, and then pulled to destruction. The criterion for passing this test was that the wires should break both before and after aging. In the defective lots, the wires lifted off of the gold film after aging. Analysis of these defective films by SEM, Auger, and TOF-SIMS suggested that residues, deposited from the plating bath, concentrated beneath the bond as the gold and aluminum reacted to form an inter-metallic compound during aging. A combination, etch and cleaning treatment was developed for defective substrates, which removed a sufficient amount of residues from the gold to pass the qualification test.