Double-Sided Boards This type of board has wiring on both sides, but in order to use the wires on both sides, there must be a proper circuit connection between the two sides. This circuit between the “bridge” is called a guide hole (via).

Guide holes are in the PCB, filled or coated with metal holes, which can be connected to the two sides of the wire. Because the double-sided panel is twice as large as the single-sided panel, the double-sided panel solves the difficulty of interlacing the wiring in the single-sided panel (you can pass through the hole to the other side), it is more suitable for use in more complex circuits than the single-sided panel.