1, KB base material 2,HASL, 35um,2-layers 3.Free sample 4.Best price and high quality Grandwork is professional and ... , Metal core AluminumSurface Finish:Hot air Lev p lead free HASL, immersion gold/silver/tin, plating gold, OSPBoard Thickness:Inner core thickness ... forward to your inquiry! FR4 1.6MM Double side PCB(Free sample)