As the trend for miniaturisation in the microelectronics field continues, metallisation connecting components has smaller and smaller dimensions, especially width and thickness. The mechanical properties of the deposited metal are very different from those of the bulk material and it is important to evaluate them accurately if the reliability of the metallisation is to be optimised. The assessment of the mechanical properties of thin aluminium metallisation is possible by nanoindentation but to extract properties useful for lifetime prediction such as yield stress or creep relaxation behaviour additional modelling is necessary using finite elements analysis (FEA). In this study evaporated aluminium layers from 50nm to 600nm thick on (100) silicon were indented to various depths. Proportional loading was used to minimise the effect of creep. The loading curves were then simulated by FEA and the results compared to identify the yield properties of the coating. Modelling data for thicker samples closely follows experimental data but for thinner coatings there is a considerable gradient in properties through the film thickness.