We have accelerated the ageing of CuAlS2 by the application ofa static electrical field for different degradation times. We haveinvestigated the admittance spectroscopy and the scanning electronmicroscopy to follow and understand the (mass-charge) coupled transportprocesses produced in the volume and on the surface of these films. Theelectrical constraint induces, after an incubation phase,an activated decrease of the resistance, followed by a susbstantialincrease correlated to the formation of an open circuit. This degradation occurs more rapidly for the films havinginitially a lower resistance, due to the thermal dissipation which increasesconsiderably the temperature to about 140 °C. Admittance spectrareveal, at low frequencies, a capacitive loop related to theformation of a charge space induced by copper diffusion. Such migrationdevelop induces the formation of copper arborescences, spreading from thecathode towards the anode. The effect of thesestructures on the properties of the degraded films is discussed in relationto electromigration and associated processes (whiskers, fracture, healing,bridge-building, ...). Also, we have noticed their similarity with fractalphenomena such as electrodeposition and dielectric breakdown.