A Study Of Accelerated Test Method For Printed Circuit Board Under Combined Environment

Aerospace electronics product now gradually present developing trends of small size and high integration degree,the quality characteristic of aerospace electronics product is obviously “longevity life and high credibility”,and the lives and reliability information use test in laboratory to be verified.To improve the efficiency of verification test in laboratory,accelerated test is widespread used in the study of life and reliability index in the industry,but the methods of accelerated test still have several problems need to be researched.Therefore this paper aims at the study of the accelerated test under temperature and vibration combined environment.On the basis of former research,the fatigue analysis method under thermal cycle and vibration combined environment summarized in this paper;then take a typical PCB in aerospace electronics product for research object,use the method of accelerated life test and finite element analysis(FEA)combined together to get the fatigue lives and accelerated factors under combined environment,and analyzed the influence of fatigue lives and accelerated factors by the coupling of stress.Firstly,according to incremental damage cumulation theory,summarized the fatigue analysis method under vibration thermal and cycle combined environment which could use in the study of this paper on the basis of three bandwidths theory under random vibration,Anand viscosity-plasticity constitutive relation and,elasticity-plasticity fatigue model.Analysis the strain changing curve of the PCB under temperature and vibration combined environment on the basis of stain data obtained from test.Take a typical PCB in aerospace electronics product for research object to obtain equivalent stress and equivalent strain nephogram used FEA method under vibration and thermal cycle environment,confirm fatigue model,and calculated the failure lives and accelerated factors of vibration.Design the accelerated research test program of PCB,conducte vibration accelerated test under normal temperature and thermal cycle environment for PCB to obtain failure model and failure times,then calculated the fatigue lives and accelerated factors by statistics analysis methods.Lastly,contrast the result of fatigue lives and accelerated factors by test and FEA,mainly confirm verify the accuracy of FEA and the fatigue analysis method,finally reach the conclusion of the accelerated factors of combined environment approximate vibration accelerated factors,and the damamge aquivalent factors of accelerated vibration under combined environment can be same as under normal temperature.The researches in this paper indicate that to typical PCB in aerospace electronics product,the method of reliability accelerated test is reasonable.And the parameter of vibration accelerated equation under combined environment is the same as under normal temperature.