Apr 03, 2020
Infrared laser and UV laser are the two most widely used lasers, so what's the difference between the two lasers? How to choose laser marking with higher requirements?
The infrared YAG laser with a wavelength of 1.06 μm is the most widely used laser source in material processing. However, many plastics and some special polymers (such as polyimide) which are widely used as the matrix materials of flexible circuit boards cannot be processed by infrared or "heat" treatment.
Because of the plastic deformation caused by "heat" and the carbonization damage on the edge of cutting or drilling, it may lead to structural weakening and parasitic conductive path, and some subsequent processing procedures have to be added to improve the processing quality. Therefore, the infrared laser is not suitable for the processing of some flexible circuits. In addition, the wavelength of the infrared laser can not be absorbed by copper even under high energy density, which limits its application range more severely.
The output wavelength of UV laser is less than 0.4 μm, which is the main advantage of polymer materials. Different from infrared processing, UV microprocessing is not heat treatment in essence, and most materials absorb UV light more easily than infrared light. The high-energy ultraviolet photons directly destroy the molecular bonds on the surface of many non-metallic materials. The components processed by this "cold" photo etching technology have smooth edges and minimum carbonization.
Moreover, the characteristics of UV short wavelength itself have advantages for the mechanical micro processing of metals and polymers. It can be focused on the points of submicron order of magnitude, so it can be used for the processing of fine parts, even at a low level of pulse energy, it can also get a high energy density, and effectively process materials. The application of micro holes in the industry has been quite extensive There are two main ways of formation:
One is to use infrared laser: heat and vaporize (evaporate) the material on the surface of the material to remove the material. This method is usually called thermal processing, mainly using YAG laser (wavelength is 1.06 μm).
The other is to use UV laser: the high-energy UV photons directly destroy the molecular bonds on the surface of many non-metallic materials, so that the molecules can be separated from the object. This way will not generate high heat, so it is called cold processing, mainly using UV laser (wavelength 355nm).