A laser transmission welding technique is commonly used to join polymers. In this technique the laser beam penetrates through the first polymer, which is transparent to the wavelength of the laser used, typically in the near infrared region, and is absorbed by the surface layer of the second polymer. This polymer is heated, and when both parts are clamped together during welding, the heat is transferred to the first polymer and the surface layers of both parts are melted. After cooling and solidification of the molten material the weld is formed.
In this study the welding parameters were defined for polymers widely used in consumer electronic devices, such as transparent polycarbonate (PC), which was laser transmission welded to colored acrylonitrile butadiene styrene/polycarbonate alloy (ABS+PC-blend). The welding techniques used were contour and quasi-simultaneous welding. The parameters varied were laser power, welding speed and size of the laser beam on the surface of the absorbing polymer. Also the tensile strengths per unit length of the laser welds made with constant line energy achieved by varying both welding speed and laser power were investigated.