One sided PCB has only one conductive layer, even though a double-sided PCB has two. This will make double sided PCBs a lot more advanced and able to deal with additional complicated circuits. PCB surface procedure is usually to include the PCB area with a protective layer to circumvent copper https://andresgklmn.theblogfairy.com/30453711/not-known-details-about-14-layer-module-pcb-circuit-board