(PCB) is a laminated sandwich structure of conductive and insulating layers. A basic printed circuit consists of a flat sheet of insulating material FR4, Rogers or Polyamide for flexible circuits, and a layer of copper foil, laminated to the substrate. Chemical etching divides the flexibil circuit imprimat rigid copper
the coating is called a solder mask. Soldermask is generally green in color but can have different colors: green, red, blue, white, black. Only the outer layers need to be rigid imprimat circuit flexibil covered with solder mask, the inner copper layers are protected by the adjacent substrate layers.
force paths be rigid circuit flexibil imprimat larger than the signal paths. In a multi-layer board, an internal layer may be mostly solid copper to act as a ground plane for shielding and power return. For microwave printed circuits, transmission lines can be laid out in a planar form, such as stripline or microstrip, with dimensions carefully controlled