bottom layer through vias. Different from single-sided PCBs that have only one conductive layer, double-layer PCBs have two conductive layers that are placed on both sides of substrate and so are components.
Therefore, advantages of double-layer PCBs can be summarized into the following aspects:
• An increase of circuit density;
• Relatively low cost;
• Reduction of board size.
Owing to its benefits, double-sided PCBs have covered a wide range of applications including power supplies, industrial control, control relays, converters, UPS system, LED lighting, hard drives, printers, mobile phone system, power monitoring, test equipment, amplifiers, traffic systems etc.