Patent GB-1081230-A (GB)
Title: Improvements in or relating to the manufacture of capacitor strips
IPC: C25B3/29
Filed: 1964-12-22
Abstract: 1,081,230. Capacitor strips. SIEMENS A.G. Dec. 22, 1964 [Dec. 23, 1963], No. 52143/64. Heading H1M. A process for the manufacture of a capacitor strip comprises forming a layer assembly by applying a first varnish layer 2 to a carrier strip 12, Fig. 7 (or 1, Fig. 1), vapour depositing a metal layer 3 on said varnish layer 2, applying on metal layer 3 a varnish layer or a dielectric strip 4, and, if desired, applying further alternate metal and varnish layers, applying an auxiliary carrier strip 12<SP>1</SP>, Fig. 7 (or 5, Fig. 2) to the face of said assembly remote from said first carrier strip, peeling off said first carrier strip, and vapour depositing a metal layer 6 on the surface of said first varnish layer 2 previously covered by said first carrier strip, and, if desired, applying a further varnish layer 7 on the metal layer 6. In Fig. 6, the metal layers extend up to the edge on one longitudinal side only of the strip so that when two such strips are rolled together to form a capacitor and the electrodes contacted by spraying metal on to the ends of the rolled assembly, the metal layers 3, 6 are conductively connected and the varnish layers 2 are in a field'-free space. Hence, the varnish layer 2 is of a material having good self-healing properties, e.g. cellulose, benzylcellulose, nitrocellulose, ethylcellulose, acetylcellulose, acetobutyl &e., or polyamides, polyacrylates, polyurethanes, and polyesters, and the other varnish layers, 4, 7 are of a material having good dielectric properties. In an alternative form, one of the metal layers extends to one longitudinal side only and the other metal layer to the other longitudinal side only so that when this single strip is rolled and the electrodes contacted, the first varnish layer 2 is dielectrically active. Hence, the varnish layer 2 is of a material having good dielectric properties, e.g. polystyrene, acetylcellulose. The auxiliary carrier strip may serve as at least part of the dielectric. The metal layers applied to the first varnish layer can be subdivided by a pattern of cracks. In Fig. 7, a supply reel 10 carries a layer assembly 11 (Fig. 1) and carrier strip 12, for example of paper impregnated with hydrocarbons. An auxiliary carrier strip 12<SP>1</SP> contacts the assembly 11 and the three strips are passed over a heated bonding roller 13 to effect bonding of the carrier strip 12<SP>1</SP> to the layer assembly 11, after which the original carrier strip 12 is peeled away from the layer assembly 11 by a roller 14 and after being conducted around rollers 15 is fed back as the auxiliary carrier strip 12<SP>1</SP>. Layer assembly 11, now on the other side of the original carrier strip, is wound on a supply reel. 16'. In. a modification (Fig. 8, not shown), the layer assembly 11 and carrier strip 12 are coiled on a supply reel 17 with the layer assembly 11 inside. The assembly 11 and strip 12 are then unreeled to break the bond therebetween, the carrier strip 12 being withdrawn and the layer assembly moving round with the reel until the face of the: layer assembly not previously bonded to the carrier strip contacts the opposite face of the carrier strip. The layer assembly and carrier strip are then withdrawn,. the carrier strip now serving as the auxiliary carrier strip, and are bonded together by passage over a heated roller. Both types of varnish layers may be formed by glowpolymerization, e.g. of ethylene.