Galvanic corrosion of electroless nickel/immersion gold plated non-permanent electric contacts used in electronic devices–direct evidence of triggering mechanism

Abstract

An electrical failure in non-permanent gold plated connectors, detected during routine testing in the assembly line of mobile phones, is investigated. The connectors are coated with Electroless Nickel/Immersion Gold (ENIG) plating. The failure was observed to be caused by galvanic corrosion of nickel underlying the gold plated surface. This was made possible due to imperfections in the gold layer, which provided access to the Nickel layer and ultimately the Copper substrate at later stages of the corrosion process. Direct evidence of this mechanism is shown both in top view and in cross-sectioned samples. The imperfections observed have rounded edges, indicating that they were formed during manufacturing of the parts, as reported in previous literature sources.