Bbc Brown, Boveri & Company, Limited

Asea Brown Boveri Inc.

Marco Rossinelli

Jens Gobrecht

William John Dawson

Roger Perkins

Wolfgang Kluge

A method for manufacturing a precursor powder for use in making a varistor is disclosed. This precursor powder is produced by preparing a homogeneous aqueous dispersion of metal oxides and/or metal hydroxides and heating the dispersion in a closed pressure reactor to a temperature between 200.degree. C. and 350.degree. C. for hydrothermally treating the homogeneous dispersion. The precursor powder produced in the afore-described method is highly homogeneous and of controlled crystal phase and morphology and after mixing with zinc oxide powder can homogeneously be reacted with the zinc oxide in a ceramic process.

Process for manufacturing a precursor powder for use in making a

In a dry etching process for patterning a substrate (2), an etching mask (4) consisting of a chemically deposited oxide, for example Al.sub.2 O.sub.3, is used and the etching is carried out in a fluorine-containing plasma. By this means, etching selectivities of more than 100 are achieved for a substrate (2) of silicon.

Growing community of inventors

Fislisbach, Switzerland

Marco Rossinelli