Thermal stability of azole-coated copper surfaces

Azole layers, such as benzotriazole and imidazole, on Cu surfaces have long been known to protect the copper surfaces from corrosion. In the fabrication of printed circuit boards, azole layers can protect the solderability of Cu surfaces by limiting the oxidation of the Cu. The thermal stability of imidazole and 5-methylbenzimidazole layers on Cu surfaces under vacuum, nitrogen, and air have been studied using Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy. These films are much more stable under nitrogen and vacuum than under air, and the decomposition mechanisms of the films are different under different atmospheres.