The electrical and mechanical performance of corroded products ongold plating after long term indoor air exposure

摘要

The corroded products formed on gold plating after long termindoor air exposure appear as a set of concentric black ringssurrounding a large corroded core on top of a pore. A visible stain isfrequently observed between and even beyond the rings. Dust particlesalso distribute on the exposed coupons. All of these insulated productscause high probability of static contact failure. Concentration of thecorroded composition increases and decreases as the morphology ischanged from the core to the rings. The contact resistance also goes upand down the same way as the composition alternates, which is high onboth the core and the concentric rings, but low on the stained areasamong the core and the rings. The contact resistance on the dark stainsalso fails, which seriously increases the failure probability. It isfound that the wearing out of the products which reduces the contactresistance depends on the normal force, geometry of the contact pairsand shearing strength of the corroded products. The effect of pores oncontact reliability is much more serious than was predicted previously,especially in low signal applications