The difference between ultraviolet laser and infrared laser
Infrared lasers and ultraviolet lasers are the two most widely used lasers. What is the difference between the processing of these two lasers? How to choose the higher requirements for laser marking?
The infrared YAG laser has a wavelength of 1.06 μm and is the most widely used laser source for material processing. However, many plastics and some special polymers (such as polyimide) used as a matrix material for flexible circuit boards cannot be finely processed by infrared processing or "hot" processing.
Because "heat" deforms the plastic, damage in the form of charring on the edge of the cut or drill hole may result in structural weakening and parasitic conduction paths, and some subsequent processing steps have to be added to improve the quality of the process. Therefore, infrared lasers are not suitable for the processing of certain flexible circuits. In addition, even at high energy densities, the wavelength of the infrared laser cannot be absorbed by copper, which more severely limits its range of use.
The output wavelength of the UV laser is below 0.4 μm, which is the main advantage of processing polymer materials. Unlike infrared processing, UV microprocessing is not inherently heat treatment, and most materials absorb UV light more easily than infrared light. High-energy UV photons directly destroy the molecular bonds on the surface of many non-metallic materials. Parts processed with this "cold" photo-etching process have smooth edges and minimal carbonization.
Moreover, the characteristics of the ultraviolet short wavelength itself are superior to the mechanical microprocessing of metals and polymers. It can be focused on points on the order of submicron, so that the processing of fine parts can be performed, even at low pulse energy levels, high energy density can be obtained, material processing can be performed efficiently, and fine pores are in the industry. The applications in this have been quite extensive, and there are two main ways to form them:
The first is to use infrared laser: the material on the surface of the material is heated and vaporized (evaporated) to remove the material, this method is usually called hot processing. The YAG laser (wavelength of 1.06 μm) is mainly used.
The second is the use of ultraviolet laser: high-energy ultraviolet photons directly destroy the molecular bonds on the surface of many non-metallic materials, so that the molecules are separated from the object, this way does not produce high heat, so it is called cold processing, mainly using ultraviolet laser
