Study On Thermal And Mechanical Properties Of Power Device IGBT Module Under Combined Loading

The power module is widely used in power transmission,wind power generation,rail transit,and other fields,and their core components include Insulated Gate Bipolar Transistor(IGBT)module.In the storage,transportation,and working environment of the IGBT module,it is often affected by a variety of loads,which leads to the early failure of the IGBT module,so it is necessary to study the failure mechanism and life of the IGBT module under multiple field loads.In this paper,the physical field coupling simulation of welded IGBT module is carried out from the point of view of thermal load,random vibration load,and fluid humidity load.According to the stress fatigue of the solder layer,the life under the temperature cycle and the life under the condition of thermal-vibration coupling are calculated.Based on the particle swarm optimization algorithm,taking the stress of the module as the optimization goal,the optimal fitness of the IGBT module under different loads is given by iterative optimization.The main research work is as follows:(1)The experimental samples are made for the upper and lower structure of the solder layer of the IGBT module,and the modal experimental analysis is carried out under different constraint states.The time domain diagram obtained from the experimental results is obtained by Fourier transform to get the frequency domain diagram,and then the natural frequencies and modal shapes of each order are obtained.According to the finite element simulation reproduction of the experimental conditions and model parameters,it is found that the error is larger when the fixed constraint condition is the bottom diagonal,and when the fixed constraint condition is the bottom four corners and the bottom plane,the error of the experiment and simulation results is less than 10%.The results verify the reliability of the simulation calculation and put forward suggestions on constraint conditions and structural layout for the finite element simulation.(2)Based on the internal package structure of a certain type of IGBT module,a simplified finite element model is established,and the steady-state thermal analysis of the module is carried out under a single temperature load.On this basis,the temperature-stress coupling analysis of the module under the condition of the temperature cycle is carried out,and the thermal stress fatigue life is calculated according to the equivalent strain of the solder layer of the substrate.The simulation results show that the stress concentration phenomenon also occurs in the chip solder layer and the substrate solder layer,and the heat flux is larger.The temperature-vibration coupling simulation of the module is carried out under the condition of a temperature cycle,and the fatigue life under the condition of random vibration is calculated based on the Gaussian distribution method.The results show that each order natural frequency of the IGBT module decreases with the increase of temperature,and the equivalent strain peak of the IGBT module appears in the first-order natural frequency and fourth-order natural frequency under harmonic vibration load,and the response frequency decreases with temperature,and the strain peak increases with temperature.At room temperature,the random vibration fatigue life of the IGBT module is about 24961.51 hours,and the fatigue life decreases with the increase in temperature.Under the condition of both thermal load and fluid load,the peak pressure on the upper surface of the IGBT module decreases gradually with the increase in temperature.(3)The data fitting and regression analysis of the finite element analysis results under multi-field loads is carried out by using the SPSS statistical analysis software,and the particle swarm optimization algorithm is realized by editing the script language on the MATLAB software.The regression analysis results are used as the particle swarm optimization space,the temperature as the particle velocity and position vector,and the module stress as the optimization results to find the best fitness.The internal relationship between stress and temperature of the module under different loads is revealed.The research results can provide a reference basis for fatigue analysis of solder layer of IGBT module in complex working environment.