Laser beam welding of copper is generally considered to be difficult, particularly due to its high heat conductivity and low absorptivity using laser sources with a wavelength of 1 µm. The resulting welds show numerous weld defects such as pores and spatters. Therefore, lasers with “blue” wavelengths are developed.

In 2017, Laserline demonstrated its first blue diode laser with a power of 500 W. The wavelength of about 445 nm revolutionized welding of copper as the absorptivity of blue light is more than ten times higher compared to conventional infrared laser light (~ 1 µm). This benefit promises a smoother welding process with less spatter, being one of the major problems when welding copper using infrared lasers. In 2022, Laserline launched its new 3 kW blue diode laser preparing the path for a broad variety of applications, especially in the e-mobility sector.

Recent investigations by Bosch at the electron-synchrotron DESY with a blue laser enabled to have a look into the material during welding. Thereby, the transition between different welding regimes, melt pool and capillary dynamics were analysed with respect to the formation of weld defects.

Furthermore, investigations showed, it can be beneficial to use a so-called spot-in-spot beam shaping tool to improve the melt pool dynamics and therefore the resulting weld quality.

It is the paper’s purpose to share these latest insights into welding of copper with a blue diode laser and to make the benefit of the blue wavelength’s absorptivity for highly reflective metals accessible.