green, red, blue, white, black. Only the outer layers need to be covered 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 soldermask ink and is applied in a thin layer similar to varnish
Impedance calculator software is a good starting point to soldermask determine the track width (w) and insulation thickness (h) of a given impedance. In terms of signal traffic in printed circuits, when the tracks carry signals at high frequencies, great care must be taken in designing the tracks to match the impedance of
of copper sheets laminated on and/or between layers of conductive substrate sheets. A printed circuit board can have several layers of copper which are almost always arranged in pairs. The number of layers and the designed interconnection between them (vias, PTHs) gives a general soldermask estimate of the