Research On Bond Wire Reliability Of IGBT Module Based On Analytical Calculation

Power semiconductor device such as IGBT module,whose packaging reliability has been widely concerned by industry and academia,is a weak links that have significant influence on the reliability of converter system,and the reliability of bond wire is one of the key factors that affect the reliability of module packaging.As an important structure for the internal electrical connection of the IGBT module,the failure of bond wires will directly affect the normal operation of the whole IGBT module,thus leading to the function of the converter can not be realized normally.Therefore,it is of great significance to study the bond wire reliability of IGBT module,which is the key to ensure the safe operation of the converter with large capacity,high power density and high reliability.The bond wire reliability of IGBT module is based on its physical failure mechanism.The traditional finite element analysis(FEA)simulation-experimental analysis method is time-consuming and difficult to calculate,so this paper proposes an analytical analysis method of bond wire failure that can greatly reduce the calculation time.This paper investigates the main failure mechanism of the bond wire in power cycling,namely,the heel crack failure and lift-off failure of bond wires.The mathematical relationship between the geometrical size of bond wires and the plastic strain at the heel of bond wires and the mathematical relationship between the crack length and the on-state voltage have been established.The physical failure mechanism of bond wire failure has been described from the perspective of analytical calculation,and the influence of various factors on the reliability of bond wire has been deeply explored.Bond wire failure is the result of the coupling action of electric-thermo-mechanical physical fields.At present,thermo-mechanical FEA method is mostly used by researchers,and there are few reports on comparative analysis of electro-thermalmechanical simulation and traditional thermal-mechanical simulation.In this paper,the temperature of IGBT module under different bonding angles has been compared and analyzed by the two simulation methods.In addition,in order to verify the analytical method for calculating plastic strain,the physical model of SKM50GB12T4 module has been established,and the FEA simulation was carried out to simulate the actual working conditions,and the FEA simulation has been calibrated by laser displacement experiment.Finally,the temperature field distribution of IGBT module under power cycling load and the mechanical parameters of the bond wire under this thermal load have been obtained.At present,life prediction models are mostly obtained by fitting existing data,which can not accurately describe and reflect the failure physical mechanism of modules.In this paper,life prediction based on failure physics has been studied by analytical calculation.A water-cooled accelerated aging experimental platform and a vibration experimental aging platform have been built.The aging data of bond wires have been obtained by loading the aging test under the actual power cyclin g conditions,the life prediction model of bond wires based on the failure mechanism has been established,and the bond wire reliability has been analyzed by the analytical calculation method proposed.