In beam welding processes, the high reflectance of copper is the main factor. At the moment when laser or electron beams strike the copper, the high reflectance of the copper surface means that only about 5 % of the energy is absorbed by the material.
In conventional welding processes, such as arc welding or gas welding, the high thermal conductivity, coupled with the melting point, poses an enormous physical demand. The component absorbs so much heat when welding is attempted that there is a risk that it will warp and dimensional accuracy can no longer be established after welding.