Abstract: An electroplating bath, cell and method for the electrodeposition of a wide range of tin-bismuth alloys onto a conductive substrate comprises tin and bismuth ion in aqueous solution, and an alkyl sulfonic or polysulfonic acid or salt as the electrolyte. The sulfonic component is present in amounts sufficient to maintain the bismuth in solution.In the operation of the method of the invention, electroplated tin-bismuth eutectic alloys of controlled composition are obtained. The alloys of tin and bismuth contain amounts of both metals such that the plated alloy has a melting point substantially lower than that of either metal alone, and a melting point lower than that of a tin-lead alloy.

Abstract: An improved electrotinplating process and acidic electroplating bath therefor is disclosed. The acidic electroplating bath contains tin ions and a chelate salt comprising an acid bismuth sulfate gluconate. An improved electrotinplating process is therefore provided which produces an electroplated tin-bismuth alloy which is resistant to the effects of tin pest and the formation of tin whiskers.

Abstract: An improved electrotinplating process and electroplating bath therefor is disclosed. The electroplating bath contains tin ions, an alkali metal hydroxide, and a bismuth compound selected from the group consisting of at least one alkali metal bismuth salt of a linear polyhydroxymonocarboxylic acid having at least six carbon atoms, at least one alkali metal bismuthyl compound of glucono-delta-lactone, and mixtures thereof. The alkali metal bismuth compounds of this invention exhibit increased solubility and long-term stability in hot alkaline alkali metal stannate electroplating baths when compared to conventional alkali metal bismuthates. A preferred alkali metal bismuth compound is an alkali metal bismuthyl gluconate. An improved electrotinplating process is therefore provided which produces a plated tin-bismuth alloy which is resistant to the effects of tin pest.