IPC-4554, Specification for Immersion Tin Plating for Printed Circuit Boards, is the third document in a series of specifications [the first two are: IPC-4552 which addresses electroless nickel-immersion gold (ENIG) and IPC-4553 which addresses immersion silver (IAg)] that set the requirements for printed circuit board surface finishes that are alternates to eutectic tin-lead. IPC-4554, a full color document, is intended for use by supplier, manufacturer, contract manufacturer (CM) and original equipment manufacturer (OEM). The immersion tin (ISn) is a metallic finish deposited by a chemical displacement reaction that is applied directly over the basis metal of the PCB, that is, copper. ISn is primarily used as a solderable surface. It has been used in press fit connections and as the interface for Zero Insertion Force (ZIF) edge connectors. The ISn protects the underlying copper from oxidation over its intended shelf life. 57 pages. Released January 2007.