Title: Leveling agent for acid zinc electroplating baths and method

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Abstract: An aqueous plating bath for the electrodeposition of a zinc coating on a substrate is disclosed and comprises zinc ions, and an amount, sufficient to provide a level zinc electrodeposit, of one or more bath-soluble leveling phosphorus cations having the formula: R.sub.4 P .sym. wherein each R is independently a hydroxy alkyl group. Baths are also described which contain, in addition to the phosphorus cations identified above, at least one nitrogen-containing compound obtained by reacting (a) ammonia, an aliphatic amine containing at least one primary amine group, or mixtures of two or more of any of these with (b) one or more epihalohydrins, glycerol halohydrins, or mixtures thereof, and at least one thiourea having the general formula: [R'.sub.2 N].sub.2 CS wherein each R' is independently hydrogen or an alkyl or alkenyl group. Methods for electrodeposition of level zinc deposits from such baths and additive compositions for preparing and maintaining the baths are disclosed.


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