With the development of electronic information technology, multi-layer PCBs are used in more and more fields. Traditionally, we define PCBs with more than four layers as “multi-layer PCBs” and PCBs with more than ten layers as “high-layer PCBs”. Whether or not a PCB manufacturer can produce high-layer PCBs is an important indicator of its strength. A PCB manufacturer that can produce high-layer PCBs with more than twenty layers is considered to be a PCB company with outstanding technical strength.