One-sided PCB board: The solder joints are concentrated on a single side, and components are usually inserted on the opposite side. Some products however have SMD components over the copper-clad aspect. Double-sided board: Either side could be format, and the two might have plug-in components or SMD components. In short, https://16-layer5-orderhdihigh-fr38271.thelateblog.com/31744955/the-2-minute-rule-for-double-sided-low-power-pcb-circuit-board