4-Layer PCB for Power Supply, Inner 4oz, Outer 4oz plated to 5oz Number of Layer:    2 – 16 Layers (1.60mm thickness) Solder Mask:    Taiyo PSR4000, Probimer 77, Sunchemical Imagecure – Series Peelable Mask:    Peters2955 Surface Finish:    Lead Free HAL, Tin-Lead HAL, Immersion Gold, Immersion Silver, Immersion Tin, Hard Gold, Flash Gold, OSP, Carbon Keypad, Gold Finger Plating.