Single-sided and Double-sided PCBis a matter of routine and design convenience at the cost of a more complicated manufacturing process. The following is a detailed introduction of these two kinds of PCB.
1.Single-Sided PCBs
Single-sided PCB is the basic one,the spare parts are concentrated on one side, and the circuit is concentrated on the other. Because the wires only appear on one side of them, so we called Single-sided PCB. Because the single-sided PCB has many strict restrictions on the design circuit (because only one side, the wiring cannot cross and must move around the individual path), it is only used on earlier circuits.
Single-sided PCB diagram mainly used Network Printing(Screen Printing), that is, resist on the copper surface; after etching, mark the welding resistance, and then finish the hole and the shape of the part by punching.

2.Double-Sided PCB
What is Double-Sided PCB? Strictly speaking, the Double-Sided PCB is one kind of the important PCB boards that is useful in the PCB industry. They allow for the routing of traces around each other by jumping between a top and bottom layer through vias. Generally speaking, there are lines on both sides! The common PCBs can be seen, such as Printed circuit boards, flexible circuit boards, Aluminum Based PCB, and High-frequency boards.
It needs circuits on both sides. Via is the holes on boards, coated with metal, and it can connect wires on both sides. The double-sided PCB area is twice as large as the Single-sided PCB, and the wiring is interleaved, which is better suited for more complex circuits.

Someone may feel confused that if one Single-Sided And Double-Sided PCB, wires on both sides while Electronic parts only one side, is this a Double-sided board or a single one? The answer is obvious. This kind of board is a Double-sided board; it’s installing a component on the Double-sided board.