This document describes a constant temperature (isothermal) aging method for testing aluminum (Al) metallization test structures on microelectronics wafers for susceptibility to stress-induced voiding. This method is valid for metallization/dielectric systems in which the dielectric is deposited onto the metallization at a temperature considerably above the intended use temperature, and above or equal to the deposition temperature of the metal. Although this is a wafer test, it is not a fast (less than 5 minutes per probe) test. It is intended to be used for lifetime prediction and failure analysis, not for production Go-NoGo lot checking.