Abstract: A transistor integrated circuit particularly for use in transaction cards such as credit cards or payment cards comprises conductive film zones on the surface of the circuit having a shape and layout which makes it difficult or impossible to determine the layout of the circuit. Additional metal zones may be formed at the level or below the level of the transistor connection strips, which cannot be eliminated without eliminating the strips. Alternatively, instead of strips, metal zones extended in two dimensions are used whereby their junction to an underlying transistor may not be easily located by observing their surface by microscopic means.