Multi-layer thin-film conductor metallizations are subject to degradation by a variety of mechanisms. Besides chemical interdiffusion and electro-migration, atmospheric corrosion of thin films in service is a potential threat if components are utilized in uncontrolled environments without hermetic packaging. Galvanic corrosion is a particular possibility when gold conductor films overlie “active” metal adhesion layers. Loss of adhesion and conductivity degradation are produced by low temperature aging in an atmosphere containing water vapor and as little as 1 ppm chlorine. All “active” metals investigated, including Ti, Zr, Mo, Nb, Ta, W, Cr and NiCr, are subject in varying degrees to corrosive attack in which atmospheric species obtain access to the active metal via pinholes in the overlying gold, and at the edges of conductor patterns. In the chlorine-water vapor atmosphere the rate of attack is a maximum at 200–250°C and is lower at both higher and lower temperatures. Sus-ceptibility to attack of large continuous film areas is shown to be reduced greatly by: (1) the introduction of an intermediate layer of Pt, Pd, or Rh between the “active” metal and the gold; (2) use of very thick (hence impermeable) gold; or (3) pinhole occlusion treatments such as vibratory ball burnishing.