The invention relates to a flexible printed circuit board, FPC, (la-c) with conductor line patterns 2, 5. The board has components 3a-d mounted on one side only and the circuit board (la-c) is folded along a dividing line (4a-c) so as to form a flat element having a top and a bottom, where the components are located only on the element's top and bottom sides. In this way, components can be mounted on the board from one side only, but after folding a double- sided element is achieved. In one embodiment, the dividing line (4a-c) is provided with fold indications, for example in the form of perforations through the FPC. In a further embodiment the dividing line 4a-c divides the board in two portions where the two portions are of different length. The invention further relates to such a flexible circuit board which is intended to form part of a catheter. Typically, the board in a first end is provided with electrical connecting elements (5) used to provide electrical connection between the catheter and other instrumentation.
