Metal laminates have experienced rapid development in many engineering applications and generally possess enhanced properties with improved service performance. Roll bonding is a major technique used in manufacture of metal laminates. This paper is to investigate the effects of atomic diffusion on the interface development of roll bonded metal laminates in the sintering heat treatment process. Copper/aluminium bi-metal laminates were prepared by roll bonding at 430oC with a 40% rolling reduction in a single pass. Sintering was then applied at 450oC for various periods. It was found that multi-phase interfacial layers developed in the sintering process and shifted towards the aluminium metal with increasing sintering time. Composition profiles of the metallic elements were carefully determined across the interfacial area of the bonded material. Interdiffusion coefficients of the metallic elements were determined using Boltzmann-Matano analysis. The results were correlated with the multi-phase development in the interfacial area.