Wire Bonding Layout And Stress Analysis Of IGBT Power Module

IGBT(Insulated Gate Bipolar Transistor)is a fully-controlled voltage-driven power semiconductor devices which is composed of power BJT(Bipolar Junction Transistor)and power MOSFET(Metal-Oxide-Semiconductor Field-Effect Transistor),IGBT is widely used in power conversion and power systems because of its high input impedance and low conduction voltage drop.IGBT module is prone to fail or fatigue in the course of work,while wire bonding and solder layer are the weakest parts of the IGBT module,so studying wire bonding failure mechanism is extremely important for improving the reliability of the module.In this paper,the model of IGBT module was established by using the finite element simulation software.Study the effect of the wire bonding layout on the temperature distribution of the chip by the electro-thermal coupling simulation.Using power cycling test to verify the simulation results.Coffin-Manson life prediction model was used to predict the lifetime of IGBT modules with different wire layout.Besides,the influence of electromagnetic force between the bonding wires on the wire fatigue was studied.Using the finite element software to carry out electromagnetic simulation,the electromagnetic force between the wires was observed from the simulation,then the influence of thermal stress and electromagnetic force under the same current level on wire bonding reliability were analyzed.The simulation results showed that the maximum temperature on the chip surface can be reduced by 3 ? by optimizing the layout of bonding wires.The experimental results of power cycling showed that the maximum temperature on the chip surface was decreased by 3 ~ 4 ? by optimizing the wire bonding layout.Using Coffin-Manson lifetime model to predict the life of IGBT modules with different layouts,it was found that the lifetime of IGBT module with high-unformity wires was 37.8% higher than that of module with low-unformity wires.By optimizing the wire bonding configuration to achieve maxmium effective heat dissipation area,the module can obtain higher reliability.Magnetostatic simulation showed that thermal stress has much greater impact on wire bonding reliability than electromagnetic force.By transient electromagnetic simulation,it was found that the electromagnetic force can not be neglected when the current peak reaches to a certain extent.At the same time,the IGBT pulse discharge experiment suggested that,the larger the pulse current peak,the stronger the magnetic field between the wires and the greater the electromagnetic force.