Fretting Wear Experiment On Au-plated Copper Contacts And Physics Of Failure Analysis

Fretting wear is the main reason resulting contact failure of electrical and electronicsystem used in the aerospace engineering. With the help of the combined stressenvironment experiment system on contact material and the surface morphology in thefretted zone, the effects of fretting frequency, fretting amplitude, current load andenvironment temperature on the fretting wear characteristics of the Au plated coppercontacts are investigated. And the failure mechanism analysis is performed byexplaining the physical process during fretting wear from both the macroscopic andmicroscopic angles.Firstly, with the help of electro dynamic shaker, the mechanical fixture can clamp thetested contacts, load the normal force and fix the normal force sensor, the tangentialforce sensor and the temperature control module. The measuring module can regulateand acquire the signals including contact resistance, the normal force and the tangentialforce. Thus the experiment system is completed with the control of the combined stressenvironment, namely the fretting frequency, fretting amplitude, current load andenvironment temperature.Secondly, the effect of fretting frequency and amplitude on the degradation of contactresistance and the tangential force of the Au plated copper contacts is analyzedexperimentally. With the surface morphology, the elemental composition analysis andsummary of the failure mechanism of the Au plated copper contacts, the three differentregimes of fretting wear are defined and the relationship between fretting regime andfretting frequency&litude is presented. In addition, the intermittency phenomenonduring the fretting process is discussed and the degradation rule of contact resistanceduring a single cycle is determined by analyzing the statistical datum of intermittencyrate.Thirdly, the effect of current load on the degradation mechanism of contact resistanceof the Au plated copper contacts is experimentally analyzed. By analyzing the surfacemorphology and the elemental composition analysis, five kinds of typical surfacemorphology are distinguished. In addition, the ability of current load melting the metalsand broking the oxide films is analyzed. The coupling effect between the currentconduction and solid dry friction is discussed.Finally, the effect of environment temperature on the degradation mechanism ofcontact resistance of the Au plated copper contacts is experimentally analyzed. Byanalyzing the surface morphology and the elemental composition, the difference incontact resistance and surface morphology between high and low temperature conditions is discussed. The result reveals that fatigue wear induced by the plasticdeformation in the fretted zone at high temperature aggravates the process of contactfailure.The method and conclusions in this paper can provide foundation for the analysis oncontact failure induced by fretting wear in the aerospace engineering, meeting the needsof high reliability and long lifetime in the electrical and electronic system.