Optimization Of Structural Design On High Power IGBT Devices

With the development of high power IGBT devices,such as 4.5 kV and 6.5 kV,they could have the ability to competing with current-driven devices based on thyristor in tractor transport and power systems.However,there are two main types of failure mechanism for conventional soldering joint IGBT,i.e.,aluminum wire bonding and solder failure.Thus,according to previous package of thyristor,novel press-pack IGBT devices through the package of pressure contact have attracted widely attention recent years.Therefore,in this paper,aiming at the design of new type high power press-pack IGBT device,insulation issues based on the method of numerical computation could be studied.Besides,through simulation and analysis,the structural design of devices could be optimized and guided,which would shorten the cycle of development and be of practical significance and value.In this paper,three aspects are included from inside to the outside of structure,namely,structure of chip terminal area,sub-module package and shell package.First of all,through building the model of terminal area of IGBT chips,multiple variables of field limited rings are analyzed about the effect on breakdown voltage such as width,spacing and number.On the basis of initial design,optimized structure could be obtained.Then,based on finite element analysis of the electric field,simulation model of IGBT sub-module could be built.Three areas of electric field intensity are proposed and analyzed,i.e.,horizontal gap,vertical gap and gap between silver and framework.According to appropriate area,practicable improvement measures such as applying resistance layer and increasing clearance are presented.Finally,for the shell of high power IGBT devices,insulation design is checked from current reference standards and finite element simulation.In addition,if the distance between sub-module and shell is too small in the analysis of simulation,combined with thin thickness of shell,the electric field distribution of shell can be affected by sub-module to some extent and so the margin needs to be considered in the actual design.