Study Of Connection Intermittent Fault Detection And Isolation Technologies In Circuit Board

As equipment service hours and application levels increase,the frequency of intermittent fault phenomena becomes more frequent.The intermittent fault has become an important factor affecting the safety of equipment maintenance and mission success.Due to the transient,random and short duration of intermittent faults,it is extremely difficult to detect and locate intermittent fault.This paper is funded by the Foundation Strengthening Project's Focused Basic Research Program.Research on intermittent fault mechanism,detection and diagnosis techniques has been carried out in response to the problem of connection intermittent fault in circuit board.The main areas of research for the paper include:(1)The mechanism of intermittent faults in circuit boardThe connection intermittent fault mechanism in circuit board is analyzed from both theoretical and experimental aspects in response to the problem of unclear intermittent fault mechanism and parameter characteristics.First,the characteristics of the two-row inline package and surface mount technology package structures are analyzed.The effect of solder joint crack on the electrical parameter characteristics of intermittent faults,including the physical causes of intermittent faults,was further analyzed.The test data of intermittent fault reproduction is then synthesized to analyze the change characteristic over time in intermittent fault parameters of solder joints under different packaging models.(2)Intermittent fault detection and test path analysisTo cover multiple connection links in circuit board with fewer test paths and improve the test efficiency,a circuit network model-based intermittent fault test path analysis method and a multichannel intermittent fault parallel detection method based on orthogonal network structure are proposed for the problem of multiple circuit board connection links and complex connection structure.First,a circuit network model under DC excitation is built based on the physical structure characteristics of the circuit board.Path edge rights are used to describe the number of connection intermittent faults in the circuit network model.Then,based on the graph search algorithm,the number of connection intermittent faults covered by different test paths is obtained.Choose the lowest cost and most effective testing path.Further,in order to realize the parallel testing of multichannel intermittent faults in electronic devices,a parallel detection method of multichannel intermittent faults based on orthogonal network structure is studied.The network structure and positioning algorithm were used to locate the path of intermittent fault occurrence.Finally,a multichannel intermittent faults simulation switch was used for experimental verification.The results show that the multichannel intermittent faults parallel test method is effective and feasible.(3)Dynamic modeling and parameter analysis of solder joints intermittent faultsFor the problem of unclear dynamic characteristics of intermittent faults,to further identify the specific solder joint where intermittent connection fault occur,dynamic modeling and characterization analysis of solder joint intermittent faults were performed.First,focusing on two typical solder joint packaging modes of SMT and DIP,two dynamic models of solder joint intermittent faults were constructed based on the structure characteristics of solder joints.The intermittent fault characteristic frequency is calculated based on the dynamic model and the sweeping vibration experiment is performed.The results show that the frequency of intermittent fault characteristics is closely related to solder joint packaging mode.Considering the dynamic changes in stiffness,the simulation analyzes the random dynamic characteristics of intermittent faults,establish the correlation between intermittent fault parameters and the stiffness of solder joint connection area,provide a theoretical basis for the intermittent fault location criterion.(4)Intermittent fault diagnosis method based on signal characteristic analysisAs intermittent fault parameter characteristics are closely related to the packaging mode,an intermittent fault diagnosis method based on signal characteristic analysis is proposed for the intermittent fault diagnosis problem.First,the intermittent fault signal is transformed with wavelets to obtain intermittent fault signal wavelet coefficient matrix.Then,considering the non-smooth nature of intermittent faults,synthesizing the time and frequency domain information of intermittent fault signals,an intermittent fault diagnosis method based on wavelet-time frequency entropy is proposed.Finally,the proposed intermittent fault diagnosis method is validated by simulation and physical experimental data,showing that it is effective and feasible.The mechanism of connection intermittent faults is analyzed for connection intermittent fault diagnosis in circuit board.From the perspective of intermittent fault detection,an intermittent fault test path analysis method based on a circuit network model is proposed.A parallel detection method of multichannel intermittent faults based on orthogonal network structure is studied.On the other hand,from the perspective of intermittent fault diagnosis,the dynamic model of typical packaging mode of solder joint connection intermittent faults is constructed,the dynamic characteristics of intermittent faults are analyzed,and the intermittent fault diagnosis method based on wavelet time frequency entropy is proposed,realizes the location of connection intermittent faults in circuit board.The above research results provide a technical way to solve the intermittent fault detection and diagnosis problem in electronic equipment.