... ROHS REACH 3.24-hour work time 4.Timely delivery speaker pcb board1,base material:FR-4 epoxy resin2,cooperthickness:1 ... of Idents25mil13Finishing TreatmentHASL (Tin-Lead Free), ENIG(Immersion Gold), Immersion Silver , Gold Plating (Flash Gold), OSP, etc.14SoldermaskGreen, White, Red, Yellow, Black, Blue ... and High Thickness copper21Thickness of Copper0.5-14oz (18-490um) speaker pcb board