Thermal Realiability Design Of Single Phase Bridge Power MOS Module

The single phase power Metal Oxide Semiconductor Field Effect Transistor(MOSFET,MOS)module has been widely applied in the field of industry and consumer electronics due to the universality and high compatibility to the drive circuit.The module has to meet increasingly stringent requirements with the increase of the application,and the advanced semiconductor manufacturing process further increase the power density result in thermal shock failure of power module.Therefore,it is necessary to improve the thermal reliability of single phase power MOS moduleIn the thesis,a single phase bridge power MOS module power consumption was calculated based on actual waveform,which model was developed by SolidWorks and simulated by ANSYS of thermal-structural analysis.The result shows that heat source,dissipation path and the heat sink are determined factors to thermal reliability of the power module.And the influence of module components on thermal reliability are analyzed subsequently.The baseplate,direct bonding copper(DBC)substrate and solder layer are the majority of the power module thermal resistance so as to block the heat transfer.The heat of power chips,bonding wires and power terminals increase the junction temperature of power module due to the parasitic Joule heat.In addition,the thermal stress induced by temperature can cause the change of the components strain,the thermal mismatch between the component layers results in the failure of the adhesive layer.Based on package structure,the components are optimized to design from the aspects of material selection,structural improvement and packaging technology selection,the high thermal reliability single phase power MOS module is realized at last.The test results show that the thermal resistance of the single phase power MOS module is reduced by 13%,and the maximum junction temperature decrease about 10%.The threshold and breakdown voltage,the on resistance of the improved module power MOS after 1000 temperature cycles are lower 1.07%,0.19%and 2.7%respectively,which meets the application requirements of the single phase power MOS module.