their legs passing through the board and glued to the pads on the other side. "SMD" components are soldered on the same side of the board. A board can use both methods for HAL soldering components. Today PCBs with components mounted only through holes are now less common. Surface
fixing the electronic components in designated locations on the outer layers by gluing. provides reliable electrical connections between the component terminals in a controlled manner HAL according to a predetermined scheme. Printed circuits are widely used in many fields: Consumer goods Military Aerospace Industrial Medical Naval The unprecedented development in recent years of all fields of
of copper), double-sided (two layers of copper on both sides of an insulating board), or multi-layered (outer and inner layers of copper alternating with insulating layers). Among the multi-layer PCBs, the most common are the four-layer ones. The HAL four-layer board has many more routing options in the internal layers compared to