surface of the printed circuit less on the soldering pads and it also has a role of antioxidation of the copper traces. Being a substance with a high degree of electrical insulation, the soldering mask offers the HASL printed circuit the possibility of having a high density of components.
of the printed circuit board conductors become significant, usually unwanted, circuit elements; rather, they can HASL be used as part of the circuit design, as in distributed element filters, antennas, and fuses, avoiding the need for additional separate components. High Density Interconnect (HDI) PCBs have traces and/or insulation less than 125
single-sided (one layer 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 four-layer board has many more routing options in HASL the internal layers compared to the