Double sided PCBs are probably the most common type of PCBs. Unlike single layer PCBs, which have conductive layer on one side of the board, the Double Sided PCB comes with conductive copper layer on both sides of the board. Electronic circuits on one side of the board can be connected on the other side of the board with the help of holes (vias) drilled through the board. The ability to cross paths from top to bottom greatly increases the circuit designer's flexibility in circuits designing and lends itself to greatly increased circuit densities. Double Sided PCBs are widely used in various electronic industries ranging from intermediate to complex circuitry.