Understanding of the Electrical Contact Performance Degradation of the Crimped Terminals under Thermal Cycling

Crimped terminals are widely used in electrical and electronic systems, where long-term reliability is highly sensitive to environmental temperature variations. However, the physical mechanisms governing electrical contact degradation under thermal cycling remain insufficiently understood. In this work, the electrical contact performance degradation of crimped terminals with tin-plated multi-strand conductors under thermal cycling is systematically investigated. Thermal cycling experiments conducted between −40 °C and 85 °C reveal a progressive and irreversible increase in the overall electrical resistance. Decomposition of the resistance components shows a clear transition from conductor-dominated resistance at the initial stage to interface-dominated resistance as thermal cycling proceeds. Then, the scanning electron microscopy and energy-dispersive spectroscopy reveal localized fretting damage at the crimped interface. Subsequently, finite element simulations demonstrate that thermal expansion mismatch between the terminal and wire conductors induces cyclic axial fretting and radial relaxation at the crimped interface during thermal cycling. Finally, a degradation mechanism is proposed in which thermally induced relative motion, fretting wear, and oxidation act synergistically to govern the irreversible increase and instability of electrical resistance. These findings clarify the physical origin of contact degradation in crimped terminals under thermal cycling and provide guidance for improving the reliability of crimped connections operating in temperature-varying service environments.