This paper describes a new welding technique for copper foils on flexible printed circuit boards and its experimental results. When an impulse current from a capacitor bank passes through a flat one-turn coil, a magnetic flux is suddenly generated in the coil. Eddy currents are induced in overlapped copper foils on the boards placed on an insulated aluminum sheet and the coil. The foils have a gap between them. The foils can be welded both by the Joule heat generated in them and by the impact effect with pulsed magnetic pressure applied to them. The bank energy required for this welding is less than 1.2 kJ.