Lognormal Probability Density Functions (pdfs) are often empirically found to fit the distribution of failure lifetimes for electronic components, but prior to this work, a physical basis has not be found for why Lognormals should be applicable. Using long-thin metal interconnects atop non-conducting substrates as a representative system, we show Lognormals pdfs for device lifetimes naturally arise, whenever there is a standard Gaussian variation in device geometry, with the case studied being variations in metal interconnect line-widths.
