The amount of heavy copper applied to the plated through-holes (PTH) plays a critical factor of the overall reliability of the printed circuit board. There are two key elements to consider. The first is the current capacity of the barrel for acceptable heat rise. The second is the mechanical strength determined by the copper thickness, hole-size and whether or not there are any support vias.
Plated through holes are holes in a printed circuit board (PCB) with copper coated walls. These holes allow electricity to be carried from one side of the circuit board through the copper in the hole to the other side of the board. On any printed circuit board of two or more circuitry layers, plated through holes form the electrical interconnection between the different layers.