This particular PCB is a 6-layer construction designed to provide reliable and stable performance for a wide range of electronic applications.They are  widely used in automatic machine, CNC controller and so on.Gold finger on printed circuits board refers to the gold-plated contacts or connectors located along the edge of the PCB, It is commonly used in PCBs that interface with other devices or components. They provide a reliable and durable connection for mating with connectors or sockets. The gold plating ensures excellent conductivity and corrosion resistance, making it ideal for applications that require frequent insertion and removal, such as memory modules or expansion cards.