A tamper evident electronic module comprises an electronic component, a tamper evident sheet, and encapsulant material. Said component is encapsulated in the encapsulant material and the sheet overlies the component, and the sheet comprises a flexible multi-layer sheet, a plurality of the layers of the sheet being selected from the group below: (i) an electromagnetic radiation shield layer; (ii) a tell-tale electrically conductive trip wire defining a convoluted meandering pathway on the layer, the trip wire meandering in a pattern which substantially covers the electronic component in a space filled area if the layer; (iii) a layer having the features of (ii), and in which the pathway comprises a fractual pattern; (iv) a layer having the features of (ii), and in which a second tell-tale trip wire extends alongside a first tell-tale trip wire so that they meander as a spaced pair. (v) an active electromagnetic marking layer adapted to emitt electromagnetic radiation.