HASL Read more about HASL /ˈhæsəl/n. "Hot air solder leveling PCB finish dipping copper in molten SnPb/SAC305 then shearing excess via air knives unlike flat ENIG."
ENIG Read more about ENIG /ˈiː nɪdʒ/n. "Electroless nickel immersion gold PCB surface finish protecting copper pads via Ni barrier + thin Au unlike HASL solder."