Printed Circuit Board of 4 layers Special thickness of 1.0 mm Special holes size of 0.015mm Red solder mask 4 layers PCB board1 ... , F4B, F4BK, F4BT, TP, PF, CEM-1, CEM-3, etc. Board thickness: 0.30 to 3.20mm (12 to 26mil) Copper ... x 620mm (18 x 24) Board finishing type: Hot air leveling, soft gold, hard gold, immersion gold, gold fingers. 4 layers Printed Circuit Board