MicroStructural Study of Fretting Contact Caused by the Difference of the Tin Plating Thickness

Ieice Transactions - IEICE 01/2008; DOI: 10.1093/ietele/e91-c.8.1199

ABSTRACT In recent years, there has been increasing demand to miniaturize wiring harness connectors in automobiles due to the increasing volume of electronic equipment and the reduction of the installation space allocated for the electronic equipment in automobiles for the comfort of the passengers. With this demand, contact failure caused by the fretting corrosion is expected to become a serious problem. In this report, we examined micro-structural observations of fretting contacts of two different tin plating thicknesses using Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) and so on. Based on the results, we compared the microstructure difference of fretting contact caused by the difference of the tin plating thickness.

  • Journal of The Japan Institute of Metals - J JPN INST METAL. 01/2009; 73(9):659-665.
  • [Show abstract] [Hide abstract]
    ABSTRACT: It is observed that contact resistance of tin plated contact in automotive connectors increased due to fretting corrosion, which is originated from heat cycle or vibration. In this study, the measurement condition is established to obtain the contact resistance distribution on fretting corrosion trace of tin plated contact in order to clarify the relationship between contact resistance and oxide formation. As the result, in the region of higher concentration of oxygen measured by EDX analysis, the contact resistance is tended to be measured higher. And the contact resistance of whole contact trace is estimated by static electric field analysis based on contact resistance distribution at contact trace. These analysis results are approximately agreement with the contact resistance on fretting corrosion experimentally. Keyword Tin plating, Fretting corrosion, Electrical contact, Contact resistance, Resistance distribution
  • [Show abstract] [Hide abstract]
    ABSTRACT: A mechanism which contributes oscillation toward electrical contacts by hammering oscillation mechanism (HOM) in the vertical direction has been developed and the influences of a micro-oscillation on contact resistance have been studied. It was suggested that the mechanism could make a study of actual degradation phenomenon on contacts by the influences of a micro-oscillation. First, a mathematical approach in the mechanism of hammering and oscillation using plate dynamic theory in time and space was carried out using continuous approximation by linearly combinations of some functions and unit step functions as external force in time and space field. According to the approach, dynamical characteristics of the mechanism were analyzed by constructing a model of a thin plate with some initial conditions, boundary conditions and transformation of wave functions. By comparing the modeling analysis with experimental results, it was shown that the analysis could express, to some extent, the actual oscillation on a thin board. Second, another mechanical model in the interface on electrical contacts was carried out by considering Coulomb's friction force and inertial force analyzed by the former model. By comparing the modeling method with experimental degradation data, it was suggested that the method could explain, to some extent, the degradation phenomenon of electrical contacts. By the models it was suggested that the dynamical characteristics of the mechanism, such as displacement, acceleration and mechanical energy, could be derived from linear combinations of basal functions. And by the methods it was thought, to some extent, that a source of the fluctuation of contact resistance caused by the hammering oscillating could be analyzed.