The failure of the main telephone system in a marine product factory due to copper sulfide (Cu2S) creep was analyzed by the measurement of hydrogen sulfide (H2S) in the atmosphere, elemental analysis with energy dispersive X-ray spectroscopy, and cross-sectional observation of vias in the printed circuit boards. Indoor H2S concentrations were higher than outdoor ones and these corresponded to the G2 and/or G3 levels defined in ISA S71.04-1985. The chemical composition of the copper sulfide creep indicates that it consisted of copper, oxygen, and sulfur. Cross-sectional observation and elemental mapping analysis showed that Cu2S creep initiated not at the edge of the organic coating (organic solder preservative, OSP) inside the vias but mainly at defects in the organic coating covering the copper.
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