enough for the current the conductor will carry. It is recommended that the power and force paths be larger than the signal paths. In a multi-layer board, an internal circuit imprimat flexibil layer may be mostly solid copper to act as a ground plane for shielding and power return. For
colors: green, circuit flexibil imprimat 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 ink and is applied in a thin
between them, i.e. the insulation. For a multilayer printed circuit with a specific stack-up, it must be taken into account that the internal tracks with controlled flexibil circuit imprimat impedance are shielded by copper planes and for this reason only the thickness of the insulation between layers and tracks and the track thickness must be taken into