Robert Boschgmbh

Herbert Forster

Dieter Handtmann

Dieter Bayer

Egon Mossburger

An electrical capacitor of a non-impregnated, self-curing type includes a roll or wound body provided with metallic layers. Interspaces between the windings of the roll are filled with a gaseous or vaporous additive substance of a polyatomic hydrocarbon compound which is free of halogens and whose ionization potential is less than the ionization potential of at least a part of decomposition products of dielectric substance of the capacitor. The additive substances makes it possible that in an electric arc of a disruptive breakdown in the dielectric material of the capacitor the charge is taken over by positive ions of the decomposition product and subsequent clusters of breakdowns are substantially prevented. In addition, the additive substances absorb during a breakdown UV photons so that the emission of secondary electrons on the metallic lining is avoided. The additive substances should be substantially free of sulfur and/or nitrogen to avoid the generation of detrimental acids or lyes which would result in the presence of unavoidable residuals of water in the dielectric material and might attack the metallic lining of the capacitor.

Electrical capacitor including a quencher gas additive

To decrease the thickness of plastic foil capacitors using, for example, polycarbonate or polypropylene foils, and permit full utilization of the dielectric strength of the dielectric material without degradation of the electrode layer applied thereto, the electrode layer, typically of aluminum or zinc, has an additive of at least one of the metals Al, Ni, Mg, Ti, Hf, Be, Bi therein, present for example as an intermetallic compound, in a quantity of from 0.5 to 10%, preferably 2 to 5% (by weight). The electrode can be applied as a vapor-deposited coating, in which the additive is uniformly distributed. The previously observed decomposition of the electrode coating under applied voltages is thereby effectively prevented. Thus, the full dielectric strength of the dielectric material is utilized, resulting in a smaller and less expensive capacitor.

Self-healing thin-layer electrical capacitor

In the manufacture of devices using a metal film deposited on a substrate of paper or synthetic resin sheet or strip material, an advantage has been found with respect to promoting adherence and resisting corrosion, when an intermediate layer is used that does not completely cover the substrate but leaves gaps between covered areas or islands. The top layer, which covers the exposed areas of the substrate and the intermediate layer, is aluminum, zinc, cadmium or zinc-cadmium. The patchy intermediate layer is an oxide or a mixture of oxides of tungsten, lead, antimony, bismuth. Oxides of certain other metals and silicon and boron oxides are also usable. Both the oxide layer and the metal layer can be vapor-deposited on a moving strip of the substrate at a foreign gas pressure of up to 1 torr. in a single pass of the substrate strip through the vacuum chamber. The oxide can be thermally deposited by vaporizing the oxide in question in vacuum or it can be formed by the action of residual oxygen or water vapor on the corresponding atoms of pure metals vaporized in the vacuum for deposition.

Thin film structure on a ribbon substrate for electric components and

The disintegration of the aluminum layer in standard capacitors which takes place as a function of electric field strength is prevented by use of a thin coating which includes a small amount of evenly distributed copper. The average percentage in weight of copper in an aluminum layer is preferably between 2 and 5 percent. The coating is vapor deposited.

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Remshalden, Germany

Herbert Forster