I am trying to understand surface finishing of PCBs. In order to do so, can somebody tell me that what kind of surface finishing Nordic uses in boards like nrf51 - DK where pads remain exposed and need long shelf life, for e.g., coin cell ground pad. My concern is that what kind of surface finish should i use in my PROTOTYPE so that it's under budget and works fine especially for exposed pads like coin cell contact pad (similarly, i have exposed programming pins). Newbie here, so ignore any stupidity.
