PRODUCTION OF METAL-FREE STRIPS ON METALLISED FOILS OF INSULATING MATERIALS

摘要

1466793 Removing metal by fusion; making capacitor foils SIEMENS AG 21 March 1974 [13 April 1973 28 Sept 1973] 12703/74 Headings B3V and B3A A metal free strip 10 is produced on a metal surface 2 of an insulating foil 1 by connecting an alternating or pulsed voltage having a frequency of at least 100 kHz between the metal surface 2 and an electrode 5, feeding the foil 1 past the electrode 5 and moving the electrode 5 such that the part coming into contact with the metal surface 2 is continuously changed, the current supplied being reduced as soon as metal removal commences. In one embodiment, an insulating foil 1 having an aluminium surface 2 is fed at 1 m./sec. over guide rollers 3, 4 which are connected to earth and one of which 3 contacts the aluminium layer. An electrode 5 in the form of a wire or band of silver plated copper, nickel-iron, copper-iron-manganese or synthetic resin coated with aluminium or carbon is guided by guides 8, 9 whilst it is fed at 0À1 mm./sec. from a reel 6 connected to a voltage source to a take-up reel 7. In another embodiment (Fig. 2, not shown) the electrode comprises a rotating disc (25) of boron nitride or titanium diboride connected to an alternating sinusoidal or rectangular voltage supply (26). The electrode disc (25) is cleaned by a rotating brush (27). The foil may be pressed against a plurality of disc electrodes (25). The metal free strip 10 produced is divided by a cutting device to produce capacitor foils.