be covered with solder mask, the inner copper layers are protected by the adjacent substrate layers. The soldering silkscreen mask soldermask is made of a fluid substance like an ink and is applied in a thin layer similar to varnish on the entire surface of the printed circuit less on the soldering pads and it also
of the PCB and has the role of a reference indicator for the components on the PCB. Graphics and text on a circuit board's PCB are usually printed with a non-conductive permanent epoxy ink. The color is usually white, although other silkscreen colors are available: yellow,
plated or metallized holes that allow interconnections between layers. PCBs mechanically support electronic components using pads for bonding the component terminals and electrically connect them using traces of one or more layers of copper sheets laminated on silkscreen and/or between layers of conductive substrate sheets. A printed circuit board can have several