Research On IGBT Module Reliability Based On Fem Method

Power semiconductor devices have new applications with the progressof design and producing technology. Compared with traditional industrialapplication, IGBTs have more harsh working conditions, such as high heatflux that caused by high power density and deep integration. Reliability is thebiggest challenge for the IGBT power modules. In addition to theconventional parameters such as voltage and current design consideration,main parameters are thermal cycling test which represents environmenttemperature variation and power cycling test which represents temperaturevariation caused by power dissipation. These two tests are importantreliability standard.In this thesis, a model has been developed by using Pro/E based onInfineon’s HybridPACK2power module. Anand model has been used todescribe the viscoelastic property of solder layer after assessment. AnANSYS FEA simulation has been used to estimate the influence of powercycling and thermal cycling to solder layer between silicon chip and the DCB (Direct Copper Bonding) substrate. Through the analysis of simulation, thedifference between power cycling and thermal cycling are found. Meanwhile,the influence of power load parameters and process parameters on powercycling test is discussed. Accumulated plastic strain increased rapidly whilepower density rised. Without considering the turn-on and turn-off losses, theimpact of the operating frequency on power cycling is minimal. Solder layerthickness. Solder thickness should be carefully designed. the larger thicknessprovides larger space on the vertical direction to share the strain caused byCTE mismatch. The peak value of stress and strain should be avoided. Thevoids close to the edge of solder layer require more attention.