To protect the copper solder pads on a PCB from oxidation, contamination and to enhance their solderability, they need to be protected with a Surface Finish and these must conform to the European Union RoHS & RoHS2 (Restriction of Hazardous Substances) Directives.
But which is the right Surface Finish for your PCB’s?
In accordance to this directive Eurocircuits offers the following Lead-free Surface Finishes:
Hot Air Levelling or Hot Air Surface Levelling (HAL or HASL).
Another important point about Lead-free soldering this that it requires higher soldering temperatures which have a direct effect on the reliability and durability of your PCB.