Thermal Analysis Of The Steering Gear Control Circuit Board And Fatigue Life Prediction Of The Solder Joints

The control circuit board is an important part of the missile steering gear,and it will inevitably experience a complex environment during service.Current research has found that temperature is the main cause of failure of electronic devices among environmental factors such as temperature,vibration,and shock.Under temperature-changing load conditions,due to the alternating effects of high and low temperature environments,cracks will occur in the solder joints on the control circuit board.As fatigue continues to accumulate,the cracks will continue to expand until the solder joints fail,which will lead to device failure.In this paper,the steering gear control circuit board is selected as the research object,and the thermal-structure coupled finite element analysis method is used to analyze the thermal response of the steering gear control circuit board under the influence of different heat sources,and further explore the heat to the dangerous solder joints under different temperature load fatigue life effect.The specific research content is as follows:(1)Under the action of the internal heat source,the thermal response of the control circuit board is analyzed using the thermal-structural coupled finite element analysis method.The results of the finite element numerical simulation are compared with the experimental data,which proves the effectiveness of the analysis method.(2)Under the load of environmental temperature change,the fatigue life prediction model based on plastic deformation predicts the fatigue life of solder joints,and deeply explores the influence of different environmental temperature load parameters on the fatigue life of solder joints.The thermal response of the control circuit board is analyzed by the thermal-structural coupling analysis method.The finite element numerical simulation results are compared with the experimental results.According to the results of thermal response analysis,dangerous solder joints is identified,and their fatigue life prediction and influencing factors are analyzed.(3)Under the combined action of internal heat source and environmental temperature load,the fatigue life prediction model based on plastic deformation predicts the fatigue life of solder joints.First,the temperature change curve of the air inside the steering gear box is measured through experiments.The temperature curve is taken as the environmental temperature change load,and the thermal response of the control circuit board under the combined action of the internal heat source and the environmental temperature change load is analyed.Secondly,the agreement between the finite element numerical simulation of thermal strain and the experimental measurement of thermal strain verifies the validity of the simulation analysis.Finally,according to the thermal response results,the dangerous position of the control circuit board under the combined action of the internal heat source and the environmental temperature change load is determined,and the fatigue life is predicted.This study can provide a reference for improving the reliability and life of electronic packaging devices,and lay a foundation for the research of accelerated test technology of electromechanical equipment under multiple stress conditions.