Immersion plating of tin-lead alloys

Abstract From the Canadian patent

A method of immersion plating a tin-lead alloy onto a metal substrate, especially a copper or copper-containing substrate, comprises immersing the substrate in a bath containing a tin salt, preferably stannous chloride and a, plumbous salt, preferably plumbous chloride and a sulphur-, containing complexing agent for the tin and the lead preferably thiourea or a thiourea derivative. The plumbous salt should be present in an amount sufficient to provide from 0.5 grams of lead per litre up to the limit of solubility of the salt. The advantages are quicker deposition without whisker growth and the ability to plate alloys containing up to 95% lead.