A multi-scale damage mechanics framework for nanoelectronics interconnects and solder joints
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Electronic package failure is the consequence of many factors such as high current density, thermal cycling load, stress gradient and etc. In most of the cases, such factors present together and lead to degradation in packaging components and the malfunction of nanoelectronic devices. A multi-scale numerical method as well as experimental techniques have been developed to investigate the damage and failure process for next generation nanoelectronics packaging solder joints and interconnects. In the experiment part, electromigration time to failure and electrical resistivity of 95.5%Sn-1.5%Ag-0.5%Cu-0.03W%Ni (SACN) microelectronics solder joints is being investigated. A new Black's type electromigration time to failure equation is developed to describe the life time versus current density and temperature. In addition to experimental work, molecular dynamics simulation is performed to reveal the vacancy sink mechanism with the aid of LAMMPS in atomic scale. In macro scale, a general partial differential equations platform of electromigration and thermomigration is presented and discretized for FEM implement. This model is implemented by coding with FORTRAN to the user interfaces provided by ABAQUS. Monte-Carlo method is proposed to connect atomic scale model with macro scale model. With this platform, extensive simulations are performed to reveal the mechanisms behind manufacturing and service phenomenon. In Chapter 6, simulations are employed to investigate the metal extrusion occurs in the aluminum back end of lines. In Chapter 7, yield strength degradation in lead free solder joints due to thermal gradient loading are investigated by numerical study and verified by experimental data. In Chapter 8, mean time to failure simulations are conducted for solder joints with different loading and boundary conditions are conducted. The results are compared with experimental data.