Electrically conductive cement containing agglomerate, flake and powder metal fillers

Abstract

An electrically conductive cement having substantially stable conductivity and resistance characteristics under high humidity conditions comprises a mixture of two epoxy resins with the proportion of each epoxy resin adjusted to provide a volumetric shrinkage in the mixture in the 4 to 16% and a conductive silver particular filler including agglomerates having size and surface characteristics that maintain stable electrical contact with an electrical component lead. The epoxy mixture is preferably a combination of a high-shrinkage epoxy resin and a lower-shrinkage epoxy resin in the appropriate amounts of each so as to produce the desired volumetric shrinkage characteristic. The conductive particle filler is preferably an admixture of silver flakes, silver powder, and an effective amount of silver agglomerates. The agglomerates are irregularly shaped particles having multiple surface indentations and recesses to produce many rough-edged salients or ridges and having a particle length, width, and thickness aspect ratio of about 1:1:1. An effective amount of such agglomerates appears to effect penetration of surface oxides when establishing the cemented connection as a result of the volumetric shrinkage of the polymeric carrier upon curing.

Dependencies are inferred from the claim text.