single-sided (one layer of copper), double-sided (two layers of copper on both sides of an insulating board), pasta sita de or multi-layered (outer and inner layers of copper alternating with insulating layers). Among the multi-layer PCBs, the most common are the four-layer ones. The four-layer board has many more
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 to ensure consistent impedance. In RF and fast switching circuits, the inductance and capacitance of the printed circuit board conductors become significant, usually unwanted, sita pasta de circuit elements; rather,
and has the role of a reference indicator for the components on the PCB. Graphics and text pasta sita de on a circuit board's PCB are usually printed with a non-conductive permanent epoxy ink. The color is usually white, although other colors are available: yellow, black, blue, red. Screen printing is used to render useful