Saline soak tests to determine the short-term reliability of an in situ thin film resistance temperature detector

With an objective to assess the short-term reliability of thin film, encapsulated resistance temperature detectors (RTDs) in corrosive environments, these were placed in aqueous soak solutions of double de-ionized water (DDI) and phosphate buffered solution (PBS) or saline for eight weeks. They were removed weekly in order to characterize the effects of the solutions on their electrical properties, as well as their thermal response. The solutions were analyzed weekly as well with an FT-IR spectrometer in order to determine if chemical reactions took place during the soak tests and optical micrographic studies were carried out too. The RTDs appeared not to suffer degradation during the period of study. Nonetheless, it turned out that the soak tests offer a user-friendly and safe approach to remove the Benzocyclobutene (BCB) layer; this is an issue that is likely to be of some interest in the electronics fabrication community.