Minghui Lin

Failure modes and FEM analysis of power electronic packaging

The development of power electronics technology is driven by the insatiate demand to control electrical power. The new power electronics devices reduce the volume of the converters by three to four orders of magnitude compared to their mercury arc predecessor. And the turn-on and turn-o0 time has decreased from milliseconds to the microseconds and even nanoseconds, depending on power level. The power range commanded by converters now extends from micro-VA to several hundreds of mega-MVA. Among the new power devices, insulated gate bipolar transistor (IGBT) devices are being more accepted and increasingly used in traction application such as locomotive, elevator, tram and subway. Thus the long-term reliability of IGBT is highly demanded. In this paper the failure modes of power electronics devices especially IGBTs are reviewed. A FEM analysis of a multilayered IGBT packaging module under cyclic thermal loading is presented.? 2001 Elsevier Science B.V. All rights reserved.

Damage mechanics of electromigration in microelectronics copper interconnects

Current density levels are expected to increase by orders of magnitude in nanoelectronics. Electromigration which occur under high current density is the major concern for the nanoelectronics industry. Using a general purpose computational model, which is capable of simulating coupled electromigration and thermo-mechanical stress evolution, several dual damascene copper interconnect structures have been investigated for electromigration damage. Different diffusion boundary conditions including blocking and non-blocking boundary conditions, current crowding effects, interface diffusion effects and material plasticity have been considered. Different damage criteria are used for quantifying material degradation. The computational simulation results match the experimental findings; therefore the model proves to be a useful tool for quantifying damage in nanoelectronics interconnects.

Modeling deformation in microelectronics BGA solder joints under high current density. Part I. Simulation and testing

In this paper, Moire interferometry technique is used to measure the in-situ displacement evolution of lead-free solder joint under electric current stressing. Large deformation was observed in solder joint under high density (10/sup 4/A/cm/sup 2/) current stressing. The deformation was found to be due to electromigration in the solder joint. An electromigration constitutive model is developed to simulate deformation of lead-free solder joint under current stressing. The simulation predicts reasonably close displacements results to Moire interferometry experimental results in both spatial distribution and time history evolution, which indicates that the electromigration model is reasonably good for predicting the mechanical behavior of lead-free solder alloy under electric current stressing. This is the first part of the papers reporting the deformation of solder joint under current stressing. More experimental results are reported in the second paper.

Damage Mechanics Modeling of Concurrent Thermal and Vibration Loading on Electronics Packaging

The problem of concurrent thermal and vibration loading has not been thoroughly studied even though it is common in electronic packaging applications. Here we attempt to address such a problem using a damage mechanics based constitutive model. Damage mechanics constitutive model for eutectic Pb/Sn solder alloys is used to simulate the damage effects of concurrent cyclic thermal loads and vibrations on Ball Grid Array (BGA) packages. The model is implemented into the commercial finite element code ABAQUS through its user defined material subroutine capability. For the integration algorithm we have used a return mapping scheme, which dramatically improves the convergency rate as compared to previous implementations of the same model. Results are examined in terms of accumulation of plastic strain within the solder connections. It is shown that the simplistic Miner’s rule can not accurately account for the combined effect of both loadings acting concurrently.

Thermomigration induced strain field simulation for microelectronic lead free solder joints

Many factors such as high intensity current, thermal load, shock load, vibration load and etc., can induce the failure in electronic equipment. It is common for electronic equipment to be subjected to a combination of the loads mentioned above simultaneously. In this paper, qualitative finite element simulations of thermomigration induced strain fields in lead free solders are conducted using a fully coupled displacement-diffusion model [1] with nonlinear mechanical material properties. The solutions are discussed and compared to experimental data as well as theoretical developments from literature.© 2006 ASME