The challenge of laser welding of copper is related to the two main physical properties of the material: the low absorptivity of most high power industrial lasers and the high thermal conductivity in the process. The absorption rate of copper increases as the wavelength decreases, which means that the visible band of lasers for copper soldering will have a significant advantage, but for most of the welding applications the required power range of these lasers is not yet available or has not yet been industrial verification. Infrared lasers have an absorptivity problem when handling solid materials. If the material is melted or evaporated by deep welding, the absorption rate will increase significantly.
Compared with the traditional process of spot welding technology, welding can be customized weld form, optimize the weld after welding strength, increased design and process flexibility, can be applied to any welding form, any welding direction. At the same time can be customized according to process requirements weld distribution, making the welding force of the optimization can be a perfect realization. Laser welding soldering without contact, flexible weld requirements, can make the welding overlap surface smaller. The use of laser welding can reduce the cost of materials to a certain extent and reduce the weight of the body, to ensure the quality of the body on the basis of the maximum to achieve light weight, but also to achieve the purpose of energy conservation.
From the market growth point of view, according to the type of laser, the next five years, the fastest growing market is the direct semiconductor lasers, mainly kilowatt-class high-power semiconductor lasers; growth is the second fastest quantum cascade laser, this advantage obviously, widely used, especially in anti-terrorism, security and other applications play an important role in the future of the global quantum cascade lasers will have a huge demand. Fiber lasers will always maintain a steady growth rate. From the application of the laser market, to remove about half of the optical communications market, the current macro-processing is the largest market, followed by micro-processing, the future with the manufacturing industry continues to high-end development, micro-processing market will have a large growing space.
In recent years, an exciting alternative process has been put into industrial applications, that is, ultra-fast laser in the near infrared wavelength range generated sub-second pulse. In this method, the ultrashort pulse is closely focused on most of the glass or surface, and the power density per square centimeter exceeds the number of tiles, causing complex and diverse processes such as simultaneous multiphoton absorption, avalanche and collision ionization, resulting in a glass the matrix is highly localized by the destruction while almost no energy deposition (only a few microfocus or less). Since the energy used for each pulse is extremely modest, the thermal effect on the part (or even the volume of the focus) is negligible.
When the ablation rate between the deep ultraviolet laser beam and the laser is compared, the ablation rate of the deep ultraviolet laser beam is higher than that of the green laser beam in the use of each material. For large band gap silicon carbide materials, deep ultraviolet beam also provides a higher ablation rate. In general, when the ablation is induced by a short pulse laser, the photon energy of the laser beam must be higher than the band gap of the workpiece material.
Since the photon energy is inversely proportional to the laser wavelength, the photon energy of the deep ultraviolet laser beam is about twice that of the green laser and higher than that of the silicon carbide SiC material.