The Performance Of Common Connector Materials Under Fretting

The electric connectors are widely used in communication, electronic and power industry, so its reliability is very important. Fretting is one of the major reasons that make electric contact unreliable.In the beginning part of thesis, the analyzing method for fretting resistance data is discussed. First, averaging the resistance data of all the tested point in every fretting cycle. Second, Median Filtering Method is used to get rid of gross error. Thirdly, Median Method or Least Square Method is used for curve fitting. Finally, all of data is saved as a text file and EXECL file in order to facilitate more in-depth analysis of data.This thesis mainly discusses the fretting performance of the commonly connector materials, including gold-plated material, nickel-plated material, copper material, stainless steel material and printed Wire board (PWB) material. Contact pairs with gold-plated on both sides of contacts show the best fretting performance. That is, contact resistance and its variation lower than 10mΩ,respectively during 20000 fretting cycles under the condition of normal force 150g and fretting amplitude 200μm. Thin gold contacts of gold plating thickness 0.4μm have the best fretting behaviors. If only one side is gold-plated material, its fretting performance is affected by the material of the other side. Contact pairs with gold-plated material and nickel-plated material have good performance, as well as contact pairs between gold-plated material and copper material. On the contrary, contact pairs between gold-plated material and stainless steel have bad performance .It can reduce the contact resistance to increase pressure or surface coating thickness for gold-plated material, but when reaching a certain scalar, the effect is limited. The contact resistance of nickel-plated material is low at the beginning of dozens of cycles, and then sharply rises and intensely changes with the increase in cycles. The effect of pressure and surface coating thickness for contact resistance of nickel-plated material is complex, and contact resistance under different conditions is in the relatively large difference. The fretting performance of copper and stainless steel material is similar to nickel-plated material, and it can be improved by changing the matching material of fretting, which gold-plated is best, nickel-plated and copper material limited and stainless steel worst. PWB material affected by its special structure has different fretting performance when the fretting area is different. When contacting on peaks, contact resistance trends to increase and intensely changes. However, when contacting in troughs, contact resistance is low and changes in smooth.