Voltage-dependent resistor
AssigneeSiemens Aktiengesellschaft
InventorsGuenter Ott, Franz Zettl
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Abstract
A voltage-dependent resistor or varistor is composed of a monolithic ceramic body made up of a plurality of layers of varistor material containing zinc oxide, alternating with layers of precious metal serving as coatings on the layers and which are alternatingly electrically connected to separate locations on the exterior surfaces of the body. The porosity of the layers of varistor material does not exceed 5%; the proportion of bismuth is at most 1 mol %; and the precious metal coatings include 50-80% by weight of palladium.
Claims7
A voltage-dependent resistor having a ceramic monolithic body composed of a plurality of layers of varistor material having a thickness in the range of 20 .mu.m to 350 .mu.m, said varistor material having grain sizes from 7 .mu.m to 22 .mu.m and being composed of zinc oxide together with up to 6 mol % additives of one or more of oxides in the group of metals Bi, Sb, Co, Ni, Cr, Mn, Mg, B, Al, and Ba, and having layers of precious metals serving as coatings with a thickness in the range equal to or less than 10 .mu.m, said coatings alternating with the layers of varistor material and alternatingly conducted to different locations on the external surfaces of said body and electrically connected together in antipolar fashion, the porosity of said layers of varistor material being equal to or less than 5%, the proportion of bismuth (calculated as Bi.sub.2 O.sub.3) in said varistor material is in the ranges 0.4-1 mol % or 2-5% by weight, and said coatings being composed of 50-80% by weight of silver and 50-20% by weight of palladium.
Dependencies are inferred from the claim text.