Implementation of Lead-Free Component Finishes in Mass Production

摘要

At this time, with approximately one year remaining before the RoHS deadline to eliminate lead from component surface finishes, implementation progress has been generally good although not without issues. The elimination of lead has focused attention on the whisker propensity of the tin-lead alternatives, and although not initially obvious pure tin is the leading candidate for replacement of tin lead. Whisker mitigation measures in the form of nickel barrier, post-plate bake or reflow have imposed additional burdens on process control requirements with respect to solderability and deposit cosmetic appearance characteristics. In order to maintain rapid and reliable surface wetting characteristics to ensure good solderability, oxide formation must be controlled with optimum process control of the tin deposit. Changes in the deposit properties as a result of post-plate baking or reflow simulation can be improved by the optimization of tin deposits' oxide resistance.