... best service Low cost PCB Assembly PCB ManufactureMaterial: FR4, High TG FR4, Halogen Free material, Rogers HF material, etc.Layer counts: 2-28 ... . drilling slot size: 0.6mmSolder mask color: green, black, blue, white, yellow, purple, and matt, etc.Solder mask hardness: 6HLegend/Silk screen Color: white ... provide technical support.5.OEM and ODM service are welcome. PCB with green solder mask factory