Abstract: A tin, lead, or tin-lead alloy plating bath comprising, as essential ingredients, an alkali metal salt, and a soluble divalent tin compound or/and a lead compound, all of an aliphatic or aromatic sulfocarboxylic acid of the general formula ##STR1## wherein R is a C.sub.1-4 hydrocarbon radical, M.sub.1 is a hydrogen atom or alkali metal atom, M.sub.2 is an alkali metal atom, and X.sub.1 and X.sub.2 are each a hydrogen atom, OH, COON, or SO.sub.3 N (where N represents a hydrogen atom or alkali metal atom).

Abstract: A tin-lead alloy plating bath based on a principal plating bath comprising an alkanesulfonic or alkanolsulfonic acid and both bivalent tin and lead salts thereof is characterized by the addition of a guanamine compound having the general formula ##STR1## wherein R.sub.1 and R.sub.2, which may be the same or different, represent each a hydrogen atom, C.sub.1-18 straight- or branched-chain alkyl radical, C.sub.1-18 straight- or branched-chain alkoxy-lower alkyl radical, or a C.sub.3-7 cycloalkyl radical, or R.sub.1 and R.sub.2 may combine to form a carbon cycle or hetero cycle, and A represents a lower alkylene radical.

Abstract: A tin, lead or tin-lead alloy plating bath, which comprises(A) a principal plating bath containing an alkanesulfonic or alkanolsulfonic acid, and either a divalent tin salt or a divalent lead salt thereof or both;(B) at least one of surfactants comprising(a) a cationic surfactant selected from the group consisting of quarternary ammonium salts, alkyl pyridinium salts, alkyl imidazolinium salts and higher alkyl amine salts,(b) an amphoteric surfactant selected from betaines, or(c) a nonionic surfactant selected from the group consisting of condensation products of ethylene oxide and/or propylene oxide with a styrenated phenol, a higher alcohol, an alkylphenol, an alkylnaphthol, a fatty acid amide, a sorbitan or a phosphate; and(C) at least one of levelling agents selected from the group consisting of alkylidene sulfamic acids, quinolinol derivatives, benzotriazole derivatives, dialkylidene o-phenylene diamines, benzaldehyde derivatives, triazine derivatives, salicylic acid derivatives and nitriles.

Abstract: A method of electroplating of tin-lead alloys, which comprises using a solution containing hydroxyalkyl sulfonic acid and its divalent tin salts and lead salts, said solution being mixed with reaction products of acetaldehyde with O-toluidine as additives for brightening.