is usually white, although other colors are available: yellow, black, blue, red. Screen printing is used to render useful information on the PCB board that can help users during assembly. It is used to mark component values, part numbers, realizare cablaje imprimate test points, polarity, etc. Screen printing
with solder mask, the inner copper layers are protected by the adjacent substrate layers. The soldering mask soldermask is made of a fluid substance like an cablaje imprimate realizare ink and is applied in a thin layer similar to varnish on the entire surface of the printed circuit less on
can be single-sided (one layer of copper), double-sided (two layers of copper on both sides of an insulating board), or multi-layered (outer and inner layers of copper alternating with insulating layers). Among the multi-layer PCBs, the imprimate cablaje realizare most common are the four-layer ones. The four-layer board has many more routing options in the internal layers