Research On Multi-physics Model And Clamping Pressure Balance Of Press-Pack IGBTs

The Press-Pack IGBT devices have plenty of advantages :low thermal resistance,strong current flow capability,no soldering and wire bonding,and the failure mode is short-circuit failure,so they are widely used in power electronic systems like wind power,locomotive traction,flexible alternative current transmission systems,and high voltage direct current.Compared to traditional potting and soldering IGBT devices,Press-Pack IGBTs have completely different structures and packaging processes,so the key technologies to be aware of are differentPressure balance is one of the key technologies for Press-Pack IGBT packaging,which is mainly studied in this paper and its influence on the temperature distribution is discussed in further when the device is turned on.By establishing the physical model of the Press-Pack IGBT device In the finite element simulation software,the influence of the internal flatness condition on the pressure balance is analyzed,and the variation of the average pressure difference with the flatness in different parallel scale of the chips is obtained.Then the thermal contact resistance and the electrical contact resistance parameters,which are dependent on the pressure,are imported to perform the multi-field coupling,and to further investigate the effect of different flatness on temperature distribution of the chips.A 24-chip parallel Press-Pack IGBT device is designed and its layout research is carried out in this paper.Four symmetrically arranged IGBT sub-modules are packaged.The junction-case thermal resistance of the device with different clamping pressure under same current excitation is compared by experiment.The results have proved the relationship between clamping pressure and the junction-case thermal resistance of the device,together with the junction temperature of the chips.The junction-case thermal resistance of the device with three different flatness under same current excitation is also compared by experiment in the paper.The results have quantitatively proved the influence of the flatness on the junction-case thermal resistance of the Press-Pack IGBT devices,together with the junction temperature of the chips.The simulation results are verified: as the clamping pressure increases and the flatness improves,the thermal resistance of the Press-Pack IGBT device decreases,thereby lowering the junction temperature of the chips.