One-sided PCB board: The solder joints are concentrated on a single facet, and components are frequently inserted on the other aspect. Some products still have SMD components to the copper-clad facet. Double-sided board: Both sides is usually layout, and both equally can have plug-in components or SMD components. Zachariah Peterson https://four-layertin-sprayingmod83715.blogtov.com/11855009/not-known-factual-statements-about-4-layer-communication-pcb