During ultrasonic ball bonding of copper wire to aluminum pad, the two alloys are joined over an immensely short period of time (<100ms), at a relatively low temperature (< 200°C). Bond formation in such condition is related to accelerated diffusional processes and formation of intermetallic compounds (IMC). Despite the industrial importance of the phenomenon, the micro-mechanism of IMC formation is not clearly understood, nor deeply studied. One of the main barriers toward understanding the phenomena is the limited capability of experimental analysis for analyzing processes occurring over short period of time. In this research, a combination of theoretical analysis and finite element simulation is used to investigate the mechanisms that lead to diffusion enhancement and, as a result, IMCs formation.

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