US Patent 11643742 Silver/tin electroplating bath and method of using the same

An electroplating bath for depositing a silver/tin alloy on a substrate. The electroplating bath comprises (a) a source of tin ions; (b) a source of silver ions; (c) an acid; (d) a first complexing agent; (e) a second complexing agent, wherein the second complexing agent is selected from the group consisting of allyl thioureas, aryl thioureas, and alkyl thioureas, and combinations thereof; and (f) optionally, a wetting agent, and (g) optionally, an antioxidant.