Abstract

PEIXOTO, A.S.  and  RAMOS, A.S.. Filmes Finos & Revelação de Impressões Digitais Latentes. C.Tecn. Mat. [online]. 2010, vol.22, n.1-2, pp.29-47. ISSN 0870-8312.

The aim of the present work is to develop latent fingerprints, in order to guarantee the quality required for a positive identification through the correspondence of characteristic points. The technique used for the development of fingerprints is magnetron sputtering. To promote the preferential deposition onto fingerprints ridges, the deposition parameters should be optimised. In this study, copper and gold thin films were produced using stainless steel substrates. After optimising the deposition parameters, the influence of the fingerprints’ age and donor were studied. The quality of the developed fingermarks was evaluated visually and through optical and scanning electronic microscopy observations. The morphology of the copper and gold thin films was examined by high resolution scanning electron microscopy. Using silicon substrates, a topographic analysis was carried out by tridimensional profilometry. The preferential magnetron sputtering deposition of copper and gold thin films, 20-30 nm thick, allows latent fingerprints to be developed. The gold films are more promising, especially for detecting non-fresh fingerprints and for conserving the developed prints since, unlikely copper, they do not oxidise with time. In fact, it was possible to detect the contours of the ridges and the characteristic points in a one-month aged impression developed by gold deposition. These films present discontinuous surface and columnar cross-section morphology, while copper thin films have a more compact morphology.

Keywords : Sputtering; Fingerprints; Thin films.

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