Reliability Assessment of Cu-Al WB Under High Temperature and Voltage Bias

Electronics in automotive underhood environments may be subjected to high temperature in the range of 125-200°C. Transition to electric vehicles has resulted in need for electronics capable of operation under high voltage bias. Automotive electronics has simultaneously transitioned to copper wire-bond from gold wire-bond for first-level interconnections. Copper has a smaller process window and a higher propensity for corrosion in comparison with gold wire bonds. There is scarce information on the reliability of copper wire bonds in presence of high voltage bias under operation at high temperature. In this paper, diffusion cell measurement under various voltages was computed to investigate corrosion rate and by using mass spectrometer which is powerful and versatile analytical tool for obtaining information about the identity of an unknown compound, its molecular mass, its elemental composition, analyze diffusion propensity according to isotopes ion distribution with mass to charge ratio and abundance. A multiphysics model for micro galvanic corrosion in the presence of chlorine is introduced. The diffusion cell is used to measure the diffusivity of chlorine in different pH values and different temperatures. Diffusivity measurements are incorporated into the 3D ionic transport model to study the effect of different environmental factors on the transport rate of chlorine. In order to investigate the effect of loading on EMC, structural physics is used to know the distribution of displacement deformation and von-mises stress. The tafel parameters for copper, aluminum and intermetallics have been extracted through measurements of the polarization curves. The multiple physics of ionic transport in presence of concentration gradient, potential gradient is coupled with the galvanic corrosion.