Intermittence detection in fretting corrosion studies of electrical contacts

Abstract

The occurrence of intermittences in electrical circuits can result in serious reliability problems particularly where low signal voltages and currents are used. It is well known that differential thermal expansion or vibration in electrical connectors can result in micromotion resulting in fretting corrosion. This can lead to an increase in contact resistance and eventual loss of electrical contact. The occurrence of electrical intermittences has been considered a precursor to contact failure associated with fretting corrosion and can cause disruption in digital circuit signals.We report the development of instrumentation that simultaneously measures the occurrence of electrical intermittences along with contact resistance during the fretting of electrical contacts. In addition, the measurement system records contact friction and normal force dynamically. Intermittences can be counted and timed with durations from 20ns to milliseconds as a function of fretting cycles and correlated with the increase in contact resistance. All systems are integrated under LABVIEW computer control software.Measurements were made on Cu-Cu and Sn-Sn ridedflat combinations. Results will be interpreted in terms of the influence of wear debris on the electrical properties of the contacts.

Intermittency phenomena in electrical connectors

“…Contrary to the results presented by Abbott et al [3], [4] and Murrell et al [5] the contact resistance decreases in the experiments presented here above approximately 200 fretting cycles to values that are expected for new contacts. An elemental analysis of the contact areas reveals that the tin-plating starts to wear through after about 100 fretting cycles and is completely worn through after about 600 cycles.…”

“…Abbott et al [3], [4] and Murrell et al [5] detect intermittences using counters and Hübner-Obenland et al [6] measure the contact resistance profile during intermittences. Skinner [7] and Malucci [8] investigate the topic theoretically.…”

“…Murrell et al [5] use a 10 mA constant current source with an open circuit voltage of 1 V. The contact is made between a coupon and a rider using copper/copper and tin/tin combinations. They define an intermittence as any event exceeding a contact resistance of 10 .…”

Degradation of road tested automotive connectors

“…Field data has shown that between 30-60% of electrical failures are attributed to connector problems [2], [3]. A typical failure is defined as a high contact resistance or intermittent contact resistance faults [4], [5]. The degradation mechanisms, which lead to a high contact resistance, have been extensively investigated over many years; this has resulted in accelerated simulated tests to aid in connector design and verification of performance [6]- [11].…”

The Relationship Between Surface Wear and Contact Resistance During the Fretting of <emphasis emphasistype="italic">In-Vivo</emphasis> Electrical Contacts

“…2008.2001162 connector systems where the conduction path across the electrical contact interface is disrupted for a short duration [2]- [5]. These events can cause difficulties with electronic systems and result in system failure.…”