We have addressed the red plague concept behind the aircraft wire degradation process in the For wire systems, there is no perfect conductor, not even a silver plated one article. However, since this issue has been spurring a new level of interest every five years, we are updating you on the new developments. To briefly summarize, red plague is the galvanic corrosion that is found on silver-plated copper wires that is often associated with high resistance/corroded wiring.
Low fluorine outgassing test in process
Recent research conducted by TE Connectivity (formerly Tyco Electronics) showed results suggesting there may be a previously unidentified mechanism for generating red plague. As part of the well-known fluorine outgassing process occurring in some polymers containing fluorine (ETFE, XL-ETFE, and PTFE), it seems like fluorine may be a key contributor in some of the modern occurrences of red plague.
It has been suggested that the outgassed fluorine from the polymer combines with hydrogen, then diffuses through the silver plating (other research has shown that oxygen can diffuse through the silver plating). Once through the silver plating, the hydrofluoric acid chemically reacts with the copper. This interaction creates stress on the interface between copper and silver and leads to cracks in the plating.
While this research did not conclusively identify outgassing fluorine as the mechanism for red plague, outgassing fluorine may be another factor to be considered during wire selection.
Michael Traskos
President, Lectromec
michael.traskos@lectromec.comMichael has been involved in wire degradation and failure assessments for more than a decade. He has worked on dozens of projects assessing the reliability and qualification of EWIS components.