GB1408075A - Capacitor foils - Google Patents

Abstract

1408075 Capacitors SIEMENS AG 5 March 1973 [6 March 1972] 10507/73 Heading H1M A composite foil for manufacturing capacitors comprises two superimposed dielectric foils each having a metal coating thereon, each coating extending to an opposite edge of the composite foil, an unmetallized margin being left at the other edge of each dielectric layer, the layer edges being so formed or arranged that when the composite foil is wound into a roll, the edge zone of each metal coating is not completely covered by the adjacent dielectric layer. As shown in Fig. 1, two dielectric strips, each a multiple of a composite foil width, each bear metallized bands 5 separated by metal-free zones 3 and a row of circular perforations are made along the centre line of each zone 3. The strips are superimposed so that the centre lines of zones 3 in one strip lie over the centre lines of bands 5 in the other, and caused to adhere together, and the assembly is cut along lines, e.g. 6 and 7 to form the composite strips. The semicircular indentations in the metal-free edges of the cut dielectric strips leave corresponding portions of the adjacent metal layer uncovered in a roll wound from the strip, which portions are accessible by the Schoop layer applied to the roll end. Alternatively (Fig. 2) a narrow strip is removed by cutting along lines 14, 15 about the centre line of metal-free band 13, and cut 16 is made along the centre line of metallized bands 12. When the cut strips are superimposed in the relative disposition shown in Fig. 2, the edge zone of each metallized coating extends beyond the adjacent dielectric edge, and is accordingly not covered by it in a roll. The composite foil may be wound on a large diameter substrate to form a mother capacitor from which individual stack capacitors may be severed.