Corrosion of Silver-Plated Copper Conductors - NEPP

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Table 4. Auger surface analysis of strands processed by different manufacturers (atomic %, per
element)
It was thought that the high-temperature processing operations applied to the
various types of insulation materials might cause them to partially decompose,
releasing monomers and carbon-oxyfluoride compounds as they were being applied to
stranded wires and braid. The average surface halide analyses are given in Table 5.
Only the kapton tape shows a significant difference, less fluoride being absorbed on
the silver surfaces than from the other insulants. The kapton has a very thin FEP film
which is sintered at a lower temperature than the melt extruded FEP insulations, and
this may account for the lower fluorine levels.
Table 5. Halide concentrations (Auger analysis, atomic %) on silver conductors having various
insulation materials
It was considered that the wire stranding and cable braiding operations might effect
a change in contamination level. Superimposed on this would be the adsorption of
halogens to the silver strand surfaces from the insulation applied. Table 6 compares
the average surface contamination levels found on unprocessed strand material with
those of processed braid and wire.
Table 6. Comparison of Auger surface analyses (atomic %) on new strands and strands processed into
wire and cable
It may be deduced from these various sets of results that the different manufacturing
operations for processing individual silver-plated strands into finished wires or cables
do modify the chemical structure of the strand surfaces. There is a marked increase in
fluorine content, presumably absorbed during the high-temperature application of
fluorocarbon insulation material to the strands.
ESA Journal 1984, Vol. 8