Single sided PCB: It means that as long as one side of the PCB board has lines (which can have holes or no holes), the other side is covered with substrate or direct insulating ink, without any lines, and placed under strong light, the entire board is transparent (except for individual boards and special process requirements). As long as one side of the cross-section has a circuit, it contains copper foil.

Double sided PCB: It refers to a commonly used double-sided PCB with circuits, which relies on copper holes as the "bridge" between the two sides of the connecting board and is placed under strong light to allow the entire PCB board to transmit light (excluding individual boards and special process requirements). As long as the outermost two sides of the PCB board contain copper foil in cross-section.

Multi layer PCB: On the basis of a double-sided board, it is like a "sandwich" with a sandwich PCB in the center (depending on the production ability, there are usually 4 to 12 layers for phones, computers, home appliances, and cars). Military or aviation, positioning, floors 8 to 20. Satellites, navigation systems, rockets, and more can reach over 60 layers, and their precision can be imagined. In fact, the CPU can also be understood as an ultra precision "PCB" in microelectronics. ）The central interlayer is generally referred to as the "inner layer". A multi-layer PCB may not transmit light as a whole or partially transmit light under strong light, and the outermost ends and center position of the cross-section contain copper foil.

When using the same board and volume for single-sided, double-sided, and multi-layer PCBs, the component of multi-layer PCBs is greater than that of double-sided PCBs and greater than that of single-sided PCBs.

Article source: Jiangmen single-sided and double-sided circuit boardhttp://www.yonghongpcb.com/