The main function of the PCB surface is to increase the wettability of the conductor pad as to the soldering. Non-chemical surfaces also have some other functions as e.g. to protect the copper below from oxidation and thus to extend the shelf life. We offer a choice of various surfaces as follows: HAL lead free, chemical tin, chemical gold, chemical silver (on request). You will find more details concerning the different coatings below to help you to find the right surface for your PCB.