Screen printing is a printing technique whereby a mesh is used to transfer ink onto a substrate, which is applied to various areas like PCB manufacturing. In PCB manufacturing process, we always name this technology as silk-screening (silkscreen) which requires specially formulated inks. Silkscreen defines the text-based, human-readable information that one finds printed onto the surface of a circuit board.
Silkscreen is normally used on the component side and the information may include warning symbols, component reference designators, component identifiers, switch settings, PCB and PCBA part numbers, test points, company logos and manufacturer marks. Besides making better use of board space, the silkscreen layer is brighter, providing better conditions for faster hand assembly. Part outlines indicate part orientation, and make it obvious when you’ve forgotten to insert a part.
There are different colors to select for PCB silk screen. When manufacturing PCB Quick turn product, white is the standard silkscreen color, other colors (black or yellow) are also available. Actually, non-standard colors can be requested but will impact your cost and your lead-time. In the photo above, you can see text and part outlines are now a different color than the traces and pads. The silkscreen layer is just ink. The ink is non-conductive and can be placed on top of traces without interference.