Description:
A double-sided printed circuit board consists of carrier material (nowadays usually FR4) with copper-clad on top and bottom. The conductor tracks are etched from these two copper layers, therefore the double-sided printed circuit board is also called two-sided PCB, 2-layer board, double layer board or bilayer.
Usually, the holes connecting the upper copper layer (TOP) and bottom copper layer (bottom) to each other, are through-plated to make an electrical connection of the two layers.
