A Multi-layer PCB surface finish is crucial for a printed circuit board as it prevents the copper (exposed traces, pads, holes and ground plains) from oxidation – a critical ingredient to high-level application performance.
A surface finish is essential for making a reliable connection between the PCB and the electronic component. A surface finish has two major functions, to provide a solderable surface for sufficient soldering components to the PCB, and to protect any exposed copper from oxidizing.