Patent ID: 6210556
Filing Date: 2001-04-03
Classification: C25D,H05K

Abstract:
An electrolyte for depositing a tin-rich tin-silver alloy upon a substrate, comprising a basis solution containing:a solution soluble tin compound and a solution soluble silver compound, wherein the tin compound is present in an amount which is greater than that of the silver compound to provide a deposit that contains about 85 to 99% by weight tin and about 0.5 to 15% by weight silver;a tin chelating agent of a polyhydroxy compound in an amount sufficient to complex tin ions provided by the tin compound; anda silver chelating agent of a heterocyclic compound in an amount sufficient to complex silver ions provided from the silver compound;wherein the silver chelating agent is a compound having the formula: ##STR2##wherein each R is the same or different and is --H, --NH, --NH.sub.2,(CH.sub.2).sub.y --CO, --(CH.sub.2).sub.y --C(O)OZ, or --(CH.sub.2).sub.y --CH.sub.3, y is 0 to 5 and Z is --H, --NH.sub.4 or an alkali or alkaline earth metal and R' is --H, --(CH.sub.2).sub.y --CO, --(CH.sub.2).sub.y --C(O)OZ, or --(CH.sub.2).sub.y --CH.sub.3, y is 0 to 5 and Z is --H, --NH.sub.4 or an alkali or alkaline earth metal.