In recent years, with the continuous development of science and technology, low-power 5W ultraviolet lasers have become more and more widely used to blacken PCB circuit boards. This technology can effectively concentrate the laser energy in a small area, causing the temperature of the area to rise rapidly, achieving the effect of instantly melting and vaporizing the copper foil on the PCB circuit board. Below, this article will introduce in detail the application of low-power 5W ultraviolet laser to blacken PCB circuit boards from several aspects.