The Life Prediction Of Electronic Packaging Structures Under Thermal Cycling And Random Vibration Loading Condition

With the rapid development of electronic packaging industry,product reliability has become one of the important research topics.According to the statistics,50% of the failure electronic products are caused by welding faults between the components and the printed circuit boards,so the life of the welding structure directly has an important effect on the life of the product.In the working environment of electronic packaging structure,the impact of temperature and vibration on life is more prominent.In this paper,the finite element analysis model of the printed circuit board equipped with typical packaging structure is established.The response analysis and life prediction of plate-level electronic packaging structure under thermal cycling and random vibration loading are the main research contents.The analysis of the ball grid array package structure under thermal cycling and random vibration is carried out firstly.The comparison between life prediction and experimental results verifies the feasibility of the selected life prediction method,and then these method are applied to the computer circuit boards credibly.First of all,the computer circuit board is used as the research object,the circuit board model is assumed and simplified.Using the Solid Works/ANSYS Workbench data interface completes the transformation from the CAD model into the CAE model.Choosing the standard of the refined saturated mode number to verify the independence of the finite element grids,the finite element model of computer circuit board with saturation mode number is obtained.Secondly,under the thermal cycling loading condition,the thermodynamic characteristics of 63Sn37 Pb solder joints are described by the Anand viscoplastic constitutive model.Thermodynamic analysis is carried out by ANSYS Workbench to obtain the variation of the stress and strain distribution and the regular of dynamic response during the process of thermal cycling and to determine the hazardous location of the computer circuit board applied thermal cycling loading.Under the random vibration loading condition,the inherent characteristics of the structure are obtained through modal analysis,and the random vibration analysis is carried out to determine the weak part of the computer circuit board applied random vibration loading.Again,the thermal fatigue life and vibration fatigue life are calculated respectively for the two vulnerable locations identified by finite element analysis.According to the method of volume weighted average and combined with ANSYS APDL,the average strain energy is obtained as the master mechanics parameter of the solder joint failure.Darveaux model based on energy is selected in order to predict the thermal cycling fatigue life of the dangerous position.On the grounds of the empirical formula of Manson high cycle fatigue and the accumulation criterion of linear fatigue damage,the Steinberg model based on Gaussian distribution is selected to predict the vibration fatigue life of the two dangerous positions respectively.Finally,the total damage is obtained by the linear damage superposition approach.On the basis of the reciprocal relationship between damage and life,the life of two dangerous positions is estimated respectively.The smaller of the two values is considered as the life of the computer circuit board under the joint loading of the thermal cycling and the random vibration.So far,the study on the life as reliability index of the electronic packaging structure in the complex engineering environment is accomplished.The research can provide a reference for the design and manufacturability of electronic packaging products.