Immersion Tin is the final finishing step in the PCB manufacturing process before components are mounted onto the board. A layer of tin, ranging in thickness from 0.5µm to 1.0µm, is applied over the copper substrate of the PCB. This method is a cost-effective solution for lead-free PCBs, resulting in a flat and uniform surface, good solderability, and high efficiency. The tin layer is typically white, hence the finish is sometimes called “white tin,” and it is applied to the copper using an chemical method. This tin surface finish protects the underlying copper from oxidation throughout the PCB’s intended lifespan.
