Solutions for fretting corrosion

Application of electronics in systems that are exposed to high vibratory and shock stresses requires the use of fretting protected electrical connections. Fretting corrosion is caused by a relative motion of mated contact surfaces and results in contact failures. This paper presents a design concept that eliminates the relative motion at the contact point by introducing an additional elastic element. When the male half of a connector assembly moves relative to the female half, the contact regions on the male and female contacts will move some distance together before they start slipping. The onset of slip is predictable and measurable. This paper discusses the formula that determines the limit from where slip starts to occur. Also discussed are the effects of connector and application parameters such as coefficient of friction, normal force, spring rate, size of displacement, and lubrication. Evidence is presented that confirms the validity of the approach. The AMP Micro-MaTch contact system is used as example. Two statements about fretting were verified extra to confirming the validity of the approach. The first is that a small motion is worse than a large motion. The second that unplated phosphor-bronze behaves better than tinplated phosphorbronze. Unplated phosphor-bronze was also tested with anti-fretting lubricant and showed very good performance.