Catalyst composition and method of preparation
AssigneeShipley Company, L.L.C.
InventorMichael Gulla
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Abstract
This invention relates to dry catalyst compositions of catalytic metals and to methods for formation of said dry compositions. The dry catalysts, upon dispersion in an aqueous acid solution, are used to render surfaces receptive to the deposition of an electroless metal. The liquid catalyst compositions from which the dry compositions are formed, are those catalyst formulations of U.S. Pat. Nos. 3,874,882 and/or 3,904,792.
Claims59
An essentially dry composition which, upon admixture with an aqueous acid solution having a pH of less than the precipitation point of the catalyst, forms a stable catalyst composition for catalyzing a substrate prior to the deposition of an electroless metal, said solution containing sufficient halide ions to render the same stable and catalytic, said halide ions being derived from said aqueous acid with which said dry composition is mixed, said dry composition or the combination resulting from mixing said aqueous acid with said dry composition, said essentially dry compositions comprising a catalytic metal in combination with tin compounds where at least a portion of said tin compounds is in stannous form in an amount whereby the molar ratio of stannous tin to catalytic metal is at least 2:1, and a member selected from the group of urea in an amount of at least one mole per ten moles of acid with which said dry composition is mixed, an extraneous halide salt in an amount of at least 0.2 moles in excess of that provided by all catalyst components including the acid with which the dry composition is mixed and mixtures thereof.
An essentially dry composition which, upon admixture with an aqueous acid solution having a pH of less than the precipitation point of the catalyst, forms a stable catalyst composition for catalyzing a substrate prior to the deposition of an electroless metal, said solution containing sufficient halide ions to render the same stable and catalytic, said halide ions being derived from said aqueous acid with which said dry composition is mixed, said dry composition or the combination resulting from mixing said aqueous acid with said dry composition, said essentially dry composition comprising palladium in combination with tin compounds where at least a portion of said tin compounds is in stannous form in an amount whereby the molar ratio of stannous tin to palladium is at least 2:1, and a member selected from the group of urea in an amount of at least one mole per ten moles of acid with which said dry composition is mixed, an extraneous halide salt in an amount of at least 0.2 moles in excess of that provided by all catalyst components including the acid with which the dry composition is mixed and mixtures thereof.
A process for the formation of an essentially dry composition which, upon admixture with an aqueous acid solution having a pH less than the precipitation point of the catalyst, forms a stable catalyst composition for catalyzing a substrate prior to deposition of an electroless metal, said solution containing sufficient halide ions to render the same stable and catalytic, said halide ions being derived from said aqueous acid with which said dry composition is mixed, said dry composition or the mixture resulting from mixing said aqueous acid with said dry composition, said process comprising the steps of providing a liquid catalyst composition that is the product resulting from the admixture of an acid solution of a catalytic metal salt, a stannous salt in molar excess of the catalytic metal salt, and a member selected from the group of urea in an amount of at least one mole per ten moles of acid with which the dry composition is mixed, an extraneous halide salt in an amount of at least 0.2 moles in excess of that provided by all catalyst components including the acid with which the dry composition is mixed and mixtures thereof, said liquid catalyst composition having a pH below its precipitation point;
- drying said liquid catalyst composition under conditions whereby substantial oxidation of stannous ions from said stannous salt is encountered;
- and mixing a stannous salt with the product obtained by drying, said stannous salt being added in an amount such that the ratio of stannous tin to catalytic metal is at least 2:1.
Dependencies are inferred from the claim text.