Experimental Investigation Of Effects Of Environment Stress On Adhesion Characteristics For Au-plated Materials

Gold plating is widely used in the micro-relay manufacturing to improve electric contact reliability,however,the cold adhesion between the surfaces of Au-plated contact pairs cause the failure of relay.In this paper,the cold adhesion characteristics experimental system of the integrated stress environment was self-developed.The cold adhesion characteristics of the micro-relay Au-plated contact material under the stress of external environment were studied,including the contact pairs cold adhesion problem caused by fretting condition and the temperature shock test condition,then the physical mechanism of micro-relay cold adhesion failure and the corresponding solutions were proposed.Firstly,designed and finished the cold adhesion characteristics experimental system of the integrated stress environment.The system has the controllable characteristics of atmospheric pressure,humidity and atmosphere type,and has the clamp of reed contact pairs,accurate positioning,simulation of breaking and closing action,simulation of fretting function,optical aided observation function.During the experiment,this system can realize the real-time synchronous collection,processing and storage of the multi-channel signals of displacement,driving force and contact voltage.Secondly,used micro-relay reed contact pairs as research object,experimental studied the fretting conditions on the influence law of Au-plated material cold adhesion characteristics,reproduced the cold adhesion failure physical phenomena,and then established the fretting condition of cold adhesion physical model,expounded the physical mechanism of Au-plated contacts cold adhesion caused by the fretting condition.According to the contact resistance characteristics of reed contact pairs breaking process which appeared cold adhesion,the physical essence of spotty contact is determined.Then detailed studied the fretting cycles,fretting amplitude and static pressure of contact pairs and surface topography parameters of contact pairs influence on Au-plated materials cold adhesion characteristics,proposed the fretting amplitude is greater than the radius of the rough peak is the necessary condition to produce cold adhesion phenomenon,provided the corresponding solutions of overcome contact pairs cold adhesive failure of engineering problems in the fretting condition.Finally,used micro-relay reed assembly as the research object,studied the environmental stress of temperature influence on reed assembly cold adhesion characteristics,and concluded that the root cause of the relay temperature shock cold adhesion failure is that the process of temperature shock inducing fretting between contact pairs.At the same time,the problem of relay high frequency vibration cold adhesion failure and the failure of the surface pollution of the reed assembly were analyzed.On the basis of this,the measures to resolve the failure of the relay cold adhesion were proposed.The results of this paper has great practical significance to directly solve the cold adhesion failure of micro-relay.Meanwhile the results are instructive for the analysis of electrical contact reliability in electrical and electronic engineering.