Impact of corrosive environment on contact resistance of infrequently mated connectors

Separable connectors are commonly plated with gold for optimum electrical properties. In aggressive environments, gold provides adequate resistance for corrosion of underneath copper. Corrosion resistance has been historically studied by exposing the connectors to a mixture of corrosive gases through a mixed flowing gas (MFG) test. A few studies in the past claimed that contact electrical resistance can stay stable even in unplated samples if micromotion between the interfaces can be eliminated. However, contact force relaxation and micromotion can disturb the mating interface resulting in resistance increases. To understand the interactions between surface finish plating, end usage and micromotion under an aggressive environment, a DOE was planned with linear edge connectors in a MFG chamber. The effect of end usage was addressed through mated and unmated connector samples followed by electrical testing. The impact of mechanical force was studied by controlling the micromotion through a custom vibration fixture that was designed to operate within the MFG chamber. Results from our studies are expected to initiate efforts towards improving existing industry test standards with recommendation to consider the effects of mechanical retention and end usage in addition to plating material and thickness.