TIN-PLATING, TIN-NICKEL ELECTROPLATE AND TIN-PLATING OVER NICKEL AS FINAL FINISHES ON COPPER
Author: Phillip E. Hinton Company: Hinton “PWB” Engineering Date Published: 9/10/1996
Surface Mount International
Abstract: Tin-plating over copper for printed boards is a solderable lead free substitute for other final finishes. It can be applied by conventional printed board manufacturing process. Concern over tin whiskers and tin pest and ways of decreasing these possible problems are discussed. Tin-nickel alloy electroplate as a final finish for printed boards is used for SMT applications. This final finish has some advantages over other conventional finishes. Discussed are the benefits seen when using a single non-melting electroplate during printed board fabrication, the ease of applying solder masks, the flatness of the lands and other desired assembly characteristics. Electrolytic tin-plate on SMT lands can be a lead-free substitute for tin-lead platings or even hot-air-leveled-solder coating. Advantages of pure tin-plating or a slightly alloyed tin-plating covering a nickel electroplate are discussed related to the concerns of the printed board manufacturer, the assembler and the final user. Addressed are reliability, cost, applications and the fabrication and assembly processes.