The task of the surface finish is protecting the copper from oxidation and thereby increasing the shelf life.
In addition, the surface finish has the task to increase the wettability of the pads during soldering.As one of the last steps in PCB production, therefore, the exposed copper surfaces on the circuit board are coated with the surface finish.
The selectable surface finishes vary in shelf life, typical application and price.
However, the surface finish is usually dictated by the further processing steps, the final product, or the intended site of use of the final product.
Etal Ltd. offers the following surface finishes: