Improved stress-cracking resistance of laser welded amorphous thermoplastics by means of adapted wavelengths

摘要： Laser transmission welding is widely used for the creation of strong, hermetic and optically appealing joints between thermoplastic parts. Amorphous polymers like polycarbonate and poly(methyl methacrylate) offer excellent optical properties, making them suitable for this joining technique and especially attractive for lighting and decorative applications, for example in the automotive industry. However, the rapid and non-uniform temperature changes during the process can lead to residual stresses, which can impair weld strength and result in part failure due to environmental stress cracking. In this work it was found, that the application of 2 μm laser radiation can lead to reduced stress-cracking-susceptibility compared to conventional laser transmission welding with wavelengths of ~1 μm.