IPC 4554-WAM1

IPC-4554, Specification for Immersion Tin Plating for Printed Circuit Boards, is included in the IPC-455X series of specifications that set the requirements for printed board surface finishes that are alternates to non-coplanar finishes, most often referred to as tin-lead HASL finish. This specification is a full-color document that is intended for use by the supplier or printed board fabricator, plating chemistry supplier, contract assembler or EMS facility and the original equipment manufacturer (OEM). The immersion tin (Sn) is a metallic finish deposited by a chemical displacement reaction that is applied directly to the basis metal of the printed board, which is copper. The immersion tin is primarily used as a solderable surface for attachment of components. It may also be used when press fit connections are employed and for zero insertion force (ZIF) edge connectors. The immersion tin finish protects the underlying copper from oxidation over the intended shelf life of this finish that is described in IPC/EIA J-STD-003 as a Category 3 coating durability finish (storage of greater than six months). The inserted Amendment 1 provides more detail on the solderability of the immersion tin, using both tin-lead as well as "lead-free" solders using appropriate fluxes.