常用触点材料表面腐蚀物微动电特性研究

针对常用连接器触点材料(镀金、镀镍、镀锡),研究工业环境对其表面的腐蚀性及对触点微动电特性的影响。经过长期室内自然暴露后,镀金、镀镍、镀锡表面生成了离散的呈岛状分布的腐蚀产物。在腐蚀产物上进行了微动实验,发现在自然腐蚀产物的表面初始电阻高于通常的失效标准(10 mW),有的甚至达到1 W。当岛状腐蚀产物在微动过程中被逐渐磨掉后,接触电阻也由跳动渐渐降低至有效值。而当磨损碎屑堆积在微动痕迹附近,或接触表面之间嵌入尘土颗粒,或者在接触区内的腐蚀产物经微动后反而被挤压得更致密时,接触电阻会升高,甚至开路,造成电接触失效。腐蚀产物在微动中的去除与腐蚀物形貌及其机械特性直接相关。

Investigation on Electrical Behavior of Corroded Products on the Surfaces of Several Contact Materials During Fretting

Investigated is the effect of industrial environment on surface corrosion and electrical behaviors of several contact materials (gold, nickel and tin plating). Some scattered island corrosion products would appear on various plated surfaces after a long exposure to indoor air. Micro-movements were applied on the corroded products of gold, nickel and tin plated surfaces respectively to simulate the electric contact behavior during fretting. It was found in common that the initial static contact resistance was higher than normal limitation (10 mW) on the corroded surfaces, even reached 1W. The fretting contact resistance fluctuated and dropped to normal when the island corrosion products were worn away from the contacts. However, when the wear debris was accumulated at the vicinity of the fretting tracks, or dust particles were inlayed between the contact interfaces, or the corrosion products still remained and pressed compactly at the contacts, contact resistance can be seriously raised up, and caused contact failure. The removing of the corrosion products in fretting depended on the morphology and mechanical properties of the corroded products.