| abstract |
It now has been found that a smooth, level, matte and/or bright deposit of tin, lead or tin-lead alloy can be deposited on a substrate from an aqueous plating bath which comprises (A) at least one bath-soluble metal salt selected from the group consisting of a stannous salt, a lead salt, or a mixture of stannous and lead salts; and (B) at least one alpha-acetylenic alcohol or glycol of the formula R1R2C(OH)C 3BOND CR3 (I) wherein R1 and R2 are each independently H, an alkyl group, a cycloalkyl group or R1 and R2 together with the carbon atom form a cyclic group, provided that at least one of R1 and R2 is an alkyl group containing at least three carbon atoms, and R3 is H, an alkyl group or -C(OH)R1R2. Preferably the plating baths do not contain fluoride or fluoborate ions, and the baths are also free of strong inorganic acids such as sulfuric acid. |