Fretting Wear Characteristics Study And Reliability Assessment Of Electrical Connector Contactor

Electrical connector is a key component in electronic system to realize the signal transmission and power transmission.It is widely used in 5G communication,automotive electronics,aerospace,military and other fields.The continuous external vibration stress could cause fretting of electrical connectors contactor,the corresponding electrical contact failure is one of the basic reasons of electrical connectors functional failure,also it is the bottleneck that restricts the development of electrical connectors towards the high reliability and long service life.The fretting wear conditions include fretting adhesion and fretting slip,which reflect the relative motion state of contactor contact interface,and play a decisive role in the wear,elastoplastic deformation and electrical contact performance degradation of the surface coating and base material.Up to now,there are few theoretical analysis on the contactor fretting wear conditions,and the dynamic electrical contact resistance(ECR)model of contactor with the fretting adhesion condition and the reliability assessment method of contactor with the fretting slip form are not perfect.The contact normal force and fretting amplitude are the key factors affecting the contactor fretting wear.The contactor manufacturing parameters dispersion often leads to the contact normal forces present distribution characteristics.The dispersion of electrical connector assembly parameters will limit the fretting amplitude in a certain range.On the basis of considering the distribution of contact normal forces and the range of fretting amplitude,the types of contactor fretting wear conditions are determined,the ECR dynamic characteristic model with fretting adhesion condition of contactor is established,and the reliability assessment method of contactor fretting slip is proposed.Firstly,the types of contactor fretting wear conditions are analyzed by considering the distribution of contact normal forces and the range of fretting amplitude.The theoretical model of contactor contact normal force are established,and the model is verified by finite element method.By considering the dispersion of contactor manufacturing parameters,the contactor digital assembly model is built,and the corresponding contact normal forces distribution is calculated.Considering the size and tolerance of electrical connector each assembly part,the contactor fretting amplitude range is obtained based on the size chain.On this basis,the normal displacement characteristics of contactor are analyzed with the normal load,and it is determined that the contactor normal fretting condition is only fretting adhesion.And then,the displacement characteristics of contactor with the tangential load are analyzed,and the distribution of contact surface shear stress is obtained,the contactor tangential fretting conditions,including fretting adhesion and fretting slip,are determined.Secondly,the electrical contact characteristics of contactor in the condition of fretting adhesion are analyzed and explained by the theoretical method.By the test method,the normal fretting conditions analysis result of contactor is verified,and the dynamic ECR characteristics of contactor are obtained.Combing the method of measurement with distribution test,the height distribution function of contactor rough surface asperities is established.On this basis,based on the G-W rough contact surface model,the asperity is equivalent to a compression spring,and the dynamic contact normal force model of contactor is established from the point of view of micro-contact mechanics.Furthermore,according to the electrical contact theory,the dynamic ECR model of contactor is established.Based on the test data,the undetermined parameters in the ECR model are solved.Thirdly,considering the normal forces distribution,the fretting slip reliability assessment method of contactor is established,the quantitative analysis of manufacture parameters distribution influence on the fretting slip reliability of contactor is realized.By the test method,the division results of contactor fretting conditions are verified,the contact performance degradation law of contactor is analyzed,the degradation process of contact performance is clarified.On this basis,the lifetime theoretical calculation models of surface coating and base material of contactor are established.Furthermore,the fretting slip lifetime of contactor digital model is calculated,and the distribution types and parameters of fretting slip lifetime are obtained statistically.At last,considering the variation of fretting amplitudes,the fretting slip reliability assessment method of contactor is established,and the quantitative analysis of the assembly parameters distribution influence on the contactor fretting slip reliability is realized.In case of tangential fretting,the influence of fretting amplitudes on the degradation law of contact performance is analyzed by the test method,the ECR degradation data is obtained.According to the reaction theory model,the mean value function of degradation quantity is obtained,and the two parameters Weibull distribution is selected to describe the degradation distribution of ECR,and then the degradation distribution model of ECR is established.On the premise of ensuring the consistency of the degradation mechanism,the multiple stress levels are synthesized respectively,and the maximum likelihood method is used for the overall statistics.The estimated values of undetermined parameters in the degradation distribution model are deduced and obtained.Thus,the functional relationship between the fretting amplitudes and the contactor fretting slip reliability is established.