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Abstract

Aqueous acidic copper plating baths and processes for electrodepositing bright and level copper coatings are described. In addition to containing one or more bath-soluble copper salts, free acid and chloride ions, the copper plating baths of the invention contain a brightening compound and a heterocyclic nitrogen or sulfur-nitrogen compound. The brightener compounds are prepared by reacting a mixture of (a) a disulfide having the formula [RR'NCS.sub.2 ].sub.2 (Formula I) wherein R and R' are each independently hydrogen, alkyl or aryl groups, (b) a halo hydroxy sulfonic acid having the formula X(CH.sub.2).sub.n CH(OH)CH.sub.2 SO.sub.3 M (Formula II) wherein X is a halogen, n is 1 or 2 and M is hydrogen or an alkali metal, and (c) an aliphatic aldehyde having up to 3 carbon atoms in (d) an aqueous alkaline medium. The heterocyclic compound may be 2-thiazolidinethione or its lower alkyl derivatives, 2-imidazolidinethione or its lower alkyl derivatives, and bath-soluble reaction products of these thione compounds with an alkyl aldehyde or dialdehyde.

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First Claim